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QUANTIFYING COMPUTED RADIOGRAPHY (CR) AND DIGITAL
RADIOGRAPHY (DR) IMAGE QUALITY AND PATIENT DOSE FOR PEDIATRIC
RADIOLOGY
By
KENNITA A. JOHNSON
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
2003
Copyright 2003
by
Kennita A. Johnson
To my parents, Kenneth and Barbara Johnson and my brother, Kenneth Javae Johnson.
ACKNOWLEDGMENTS
I would like to express sincere gratitude to the members of her committee, Dr.
David E. Hintenlang, Dr. Manuel M. Arreola, Dr. Wesley E. Bolch, Dr. Jonathan L.
Williams, Dr. Johannes H. van Oostrom, Dr. William Properzio and Dr. Libby Brateman
for their wisdom and patience. I would like to extend an extra appreciation to Dr.
Hintenlang for his patience over the last seven years. I would like to give special
recognition to my committee co-chair Dr. Arreola for his technical expertise and for
lending an ear. I would like to thank Dr. Lynn Rill for all of her insight and advice. I
would like to thank the technologist in the Department of Radiology at Shands Hospital
at the University of Florida, especially Fred and Sheri for their expertise.
I would like to thank Children’s Miracle Network, NIH, Department of Radiology,
Department of Biomedical Engineering, Department of Nuclear and Radiological
Engineering for their continued funding of the project.
I wish to thank my family and friends for their inspiration and encouragement,
especially Bennie for keeping the insanity under control. Finally, I would like to extend a
special appreciation to my parents, Kenneth and Barbara Johnson and her brother,
Kenneth Javae Johnson for their unconditional support and allowing me to follow my
dreams.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS ................................................................................................. iv
LIST OF TABLES........................................................................................................... viii
LIST OF FIGURES ........................................................................................................... xi
ABSTRACT..................................................................................................................... xix
CHAPTER
1
INTRODUCTION ........................................................................................................1
Digital Imaging Basics .................................................................................................2
Image Processing...................................................................................................3
Picture Archiving and Communications Systems (PACS) ...................................4
Computed Radiography ................................................................................................5
Digital Radiography....................................................................................................10
Computed Tomography ..............................................................................................13
Image Quality .............................................................................................................15
Contrast................................................................................................................15
Spatial Resolution................................................................................................18
Noise....................................................................................................................20
Image Quality Measurements .....................................................................................21
Modulation Transfer Function....................................................................................22
Noise Power Spectrum ........................................................................................27
Detective Quantum Efficiency ............................................................................28
Patient Dose ................................................................................................................30
Image Quality, Dose and Radiographic Technique....................................................31
Summary.....................................................................................................................34
2
HYPOTHESIS............................................................................................................36
3
LITERATURE REVIEW ...........................................................................................38
4
MEAUREMENT OF IMAGE QUALITY .................................................................45
Introduction.................................................................................................................45
Materials and Methods ...............................................................................................45
v
Software...............................................................................................................45
Equipment............................................................................................................46
Modulation Transfer Function.............................................................................47
Line pair phantom method ...........................................................................47
Line spread function method........................................................................49
Noise Power Spectrum ........................................................................................50
Integral DQE .......................................................................................................51
Incident Signal-to-Noise, q..................................................................................52
Pixel Value to Exposure Conversion, k...............................................................53
Results and Discussion ...............................................................................................54
Modulation Transfer Function.............................................................................54
Noise Power Spectrum ........................................................................................58
Integral DQE .......................................................................................................61
Summary.....................................................................................................................63
5
DEVELOPMENT OF RADIOGRAPHIC TECHNIQUES .......................................64
Introduction.................................................................................................................64
Materials and Methods ...............................................................................................64
Pediatric Anthropomorphic Phantoms ................................................................64
MOSFET Dosimeters ..........................................................................................67
Dose Measurements.............................................................................................68
Image Quality Measurements..............................................................................69
Radiographic Technique Determination..............................................................70
Results and Discussion ...............................................................................................72
Relationship between IDQE and Air Kerma at the Image Receptor...................72
Relationship between IDQE and Entrance Skin Exposure..................................74
Pediatric Radiographic Techniques ............................................................................77
Effective Doses...........................................................................................................80
Summary.....................................................................................................................81
6
CONCLUSION...........................................................................................................83
APPENDIX
A
EXAMPLE OF MTF CALCULATION USING LINE PAIR PHANTOM ..............87
B
MATLAB CODES .....................................................................................................89
Modulation Transfer Function....................................................................................89
Noise Power Spectrum ...............................................................................................90
C
NOISE POWER SPECTRUM GRAPHS...................................................................93
D
INTEGRAL DETECTIVE QUANTUM EFFICIENCY GRAPHS .........................105
E
COEFFICIENTS FOR IDQE EQUATIONS ...........................................................171
vi
F
EFFECTIVE DOSE CALCULATIONS ..................................................................173
G
PROBLEMS WITH CT PHANTOMS.....................................................................239
LIST OF REFERENCES.................................................................................................242
BIOGRAPHICAL SKETCH ...........................................................................................246
vii
LIST OF TABLES
page
Table
1-1
Relationship between exposure class, mAs and exposure .........................................9
1-2
Bits and gray level relationship ................................................................................18
1-3
Resolution requirements (Hoheisel and Batz, 2000)................................................19
4-1
Measurement configurations for Agfa CR system and Canon DR system ..............51
4-2
Incident signal-to-noise ratio, q for Room 1 (Agfa CR system) and Room 5
(Canon DR system) (photons/mm2*mGy) ..............................................................52
5-1
Information on newborn and one-year-old UF phantoms ........................................66
5-2
Tube outputs (mGy/mAs) for Room 1 (Agfa CR system) and Room 5
(Canon DR system) ..................................................................................................71
5-3
The IDQE for the same entrance skin exposure (0.01 mGy) for newborn
patients. ....................................................................................................................75
5-4
The entrance skin exposure (mGy) for newborn patients for the same IDQE
value of 4..................................................................................................................75
5-5
Newborn radiographic technique chart ....................................................................79
5-6
One-Year-Old radiographic technique chart ............................................................80
5-7
Effective doses (mSv) for newborn patients using techniques in Table 5-3 ............81
A-1 Standard deviation and mean of light and dark regions of the Hüttner Phantom ....87
A-2 Calculation of the MTF ............................................................................................88
E- 1 Coefficients for the Agfa CR system at a 40 inch SID without use of the grid .....171
E-2 Coefficients for the Agfa CR system at a 40 inch SID with use of the grid ..........171
E-3 Coefficients for the Canon DR system at a 40 inch SID with the use of the grid..171
viii
E-4 Coefficients for the Agfa CR system at a 72 inch SID without the use of the
grid .........................................................................................................................171
E-5 Coefficients for the Agfa CR system at a 72 inch SID with the use of the grid ....172
E-6 Coefficients for the Canon DR system at a 72 inch SID with the use of the grid..172
F-1
Newborn effective doses for Agfa CR system at 50 kVp ......................................175
F-2
Newborn effective doses for Agfa CR system at 55 kVp ......................................177
F-3
Newborn effective doses for Agfa CR system at 60 kVp ......................................179
F-4
Newborn effective doses for Agfa CR system at 65 kVp ......................................181
F-6
Newborn effective doses for Agfa CR system at 75 kVp ......................................185
F-7
Newborn effective doses for Agfa CR system at 80 kVp ......................................187
F-8
Newborn effective doses for Agfa CR system at 85 kVp ......................................189
F-9
Newborn effective doses for Canon DR system at 50 kVp....................................191
F-10 Newborn effective doses for Canon DR system at 55 kVp....................................193
F-11 Newborn effective doses for Canon DR system at 60 kVp....................................195
F-12 Newborn effective doses for Canon DR system at 65 kVp....................................197
F-13 Newborn effective doses for Canon DR system at 70 kVp...................................199
F-14 Newborn effective doses for Canon DR system at 75 kVp....................................201
F-15 Newborn effective doses for Canon DR system at 80 kVp....................................203
F-16 Newborn effective doses for Canon DR system at 85 kVp....................................205
F-17 One-Year-Old effective doses for Agfa CR system at 50 kVp ..............................207
F-18 One-Year-Old effective doses for Agfa CR system at 55 kVp ..............................209
F-19 One-Year-Old effective doses for Agfa CR system at 60 kVp ..............................211
F-20 One-Year-Old effective doses for Agfa CR system at 65 kVp ..............................213
F-21 One-Year-Old effective doses for Agfa CR system at 70 kVp ..............................215
F-22 One-Year-Old effective doses for Agfa CR system at 75 kVp ..............................217
F-23 One-Year-Old effective doses for Agfa CR system at 80 kVp ..............................219
ix
F-24 One-Year-Old effective doses for Agfa CR system at 85 kVp ..............................221
F-25 One-Year-Old effective doses for Canon DR system at 50 kVp ...........................223
F-26 One-Year-Old effective doses for Canon DR system at 55 kVp ..........................225
F-27 One-Year-Old effective doses for Canon DR system at 60 kVp ...........................227
F-28 One-Year-Old effective doses for Canon DR system at 65 kVp ...........................229
F-29 One-Year-Old effective doses for Canon DR system at 70 kVp ...........................231
F-30 One-Year-Old effective doses for Canon DR system at 75 kVp ...........................233
F-31 One-Year-Old effective doses for Canon DR system at 80 kVp ...........................235
F-32 One-Year-Old effective doses for Canon DR system at 85 kVp ...........................237
x
LIST OF FIGURES
page
Figure
1-1
Histogram showing the number of each pixel values in an image.............................3
1-2
Mapping image brightness . .......................................................................................4
1-3
Phosphorescence process in CR plates.......................................................................6
1-4
The Agfa CR system cassette ....................................................................................7
1-5
The Agfa CR scanning procedure .............................................................................8
1-6
The Canon DR system .............................................................................................10
1-7
DR scintillation process ...........................................................................................11
1-8
DR pixel configuration.............................................................................................13
1-9
Single and multi-slice helical CT Scanners..............................................................14
1-10 Imaged and reconstructed planes in multi-slice CT. ................................................15
1-11 Image contrast. .........................................................................................................16
1-12 Linear response of input exposure to pixel value.....................................................17
1-13 Resolution of objects located in close proximity. ....................................................19
1-14 Example of a line pair phantom. ..............................................................................19
1-15 Transfer characteristics ............................................................................................23
1-16 Point and line spread functions ................................................................................24
1-17 MTF response from LSF input.................................................................................26
1-19 Two-Dimensional NPS of a flat field image ............................................................27
1-20 Quantum efficiency of materials typically used in digital images ...........................30
4-1
Hüttner phantom ......................................................................................................48
xi
4-2
Image of E1 Leeds Phantom ...................................................................................50
4-3
Pixel value vs. log of air kerma for Canon DR system ............................................53
4-4
Pixel value vs. log of air kerma*speed/200 for Agfa CR system ............................53
4-5
Image of the slit camera through a microscope........................................................55
4-6
3D image of slit camera ...........................................................................................56
4-7
Modulation transfer function of Agfa CR system using line pair function..............56
4-8
3D image of line on Leeds E1 phantom...................................................................57
4-9
Modulation transfer function for Agfa CR system and Canon DR system using
line spread function. .................................................................................................57
4-10 The noise power spectrum for Agfa CR system at 40 inch SID, without the
grid ...........................................................................................................................59
4-11 The total system noise for Agfa CR system at 40 inch SID, without the grid ........59
4-12 The NPS of all the systems and configurations at 70 kVp and 0.6 mAs. ................60
4-13 The total system noise for all systems and configurations at 70 kVp. .....................60
4-14 IDQE for various techniques for Agfa CR system at 40 inch SID without the
grid. ..........................................................................................................................62
4-15 IDQE for both systems at all configurations at 70 kVp. ..........................................62
5-1
Mathematical phantom models ................................................................................65
5-2
UF Anthropomorphic Phantom. ...............................................................................66
5-3
MOSFET dosimetry system .....................................................................................67
5-4
Anthropomorphic phantom placed on the table or at the chestboard.......................68
5-5
IDQE vs. air kerma at the image receptor for Agfa CR system at 40 inch SID
with the grid .............................................................................................................73
5-6
IDQE vs. air kerma at the image receptor for all configurations at 70 kVp ............73
5-7
IDQE vs. log of air kerma at the image receptor for Agfa CR system at 40 inch
SID with the grid ......................................................................................................76
5-8
IDQE vs. mAs used in newborn imaging at 70 kVp. ...............................................76
xii
5-9
Reduced AEC values vs. ESE for newborn For the Agfa CR system at a 40
inch SID using the grid.............................................................................................78
5-10 Image of newborn patient using Agfa CR system at 70 kVp at 40 inch SID
with grid ...................................................................................................................79
A-1 Anatomy of Hüttner line pair phantom. ...................................................................87
C-1 The NPS vs. frequency for the Agfa CR system at a 40 inch SID without using
the grid......................................................................................................................93
C-2 The NPS vs. frequency for the Agfa CR system at a 40 inch SID using the grid...94
C-3 The NPS vs. frequency for the Canon system at a 40 inch SID using the grid........95
C-4 The NPS vs. frequency for the Agfa CR system at a 72 inch SID without using
the grid......................................................................................................................96
C-5 The NPS vs. frequency for the Agfa CR system at a 72 inch SID using the
grid ...........................................................................................................................97
C-6 The NPS vs. frequency for the Canon DR system at a 72 inch SID using the
grid ...........................................................................................................................98
C-7 For the Agfa CR system at a 40 inch SID without using the grid, the area under
the NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .........................99
C-8 For the Agfa CR system at a 40 inch SID using the grid, the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .............................100
C-9 For the Canon DR system at a 40 inch SID using the grid , the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .............................101
C-10 For the Agfa CR system at a 72 inch SID without using the grid, the area
under the NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .............102
C-11 For the Agfa CR system at a 72 inch SID using the grid, the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .............................103
C-12 For the Canon DR system at a 72 inch SID using the grid, the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs) .............................104
D-1 For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.
radiographic technique (kVp and mAs). ................................................................105
D-2 For the Agfa CR system at a 40 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs). ................................................................106
xiii
D-3 For the Canon DR system at a 40 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs). ................................................................107
D-4 For the Agfa CR system at a 72 inch SID without using the grid, IDQE vs.
radiographic technique (kVp and mAs) .................................................................108
D-5 For the Agfa CR system at a 72 inch SID using the grid, IDQE vs. radiographic
technique (kVp and mAs). .....................................................................................109
D-6 For the Canon DR system at a 72 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs) .................................................................110
D-7 For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.air
kerma [mGy] at the image receptor........................................................................111
D-8 For the Agfa CR system at a 40 inch SID using the grid, IDQE vs. air kerma
[mGy] at the Image Receptor .................................................................................112
D-9 For the Canon DR system at a 40 inch SID using the gridm, IDQE vs. air
kerma [mGy] at the image receptor.......................................................................113
D-10 For the Agfa CR system at a 72 inch SID without using the grid ,IDQE vs. air
kerma [mGy] at image receptor .............................................................................114
D-11 For the Agfa CR system at a 72 inch SID using the grid, IDQE vs. air kerma
[mGy] at the image receptor...................................................................................115
D-12 For the Canon DR system at a 72 inch SID using the grid, IDQE vs. air kerma
[mGy] at the image receptor...................................................................................116
D-13 For the Agfa CR system at 40 inch SID without using the grid, IDQE vs. log
air kerma at the image receptor [mGy] ..................................................................117
D-14 For the Agfa CR system at a 40 inch SID using the grid, IDQE vs. log air
kerma [mGy] at the image receptor........................................................................118
D-15 For the Canon DR system at a 40 inch SID using the grid, IDQE vs. log air
kerma [mGy] at the image receptor........................................................................119
D-16 For the Agfa CR system at 72 inch SID without using the grid, IDQE vs. log
air kerma [mGy] at the image receptor ..................................................................120
D-17 For the Agfa CR system at a 72 inch SID using the grid, IDQE vs. log air
kerma [mGy] at the image receptor........................................................................121
D-18 For the Canon DR system at a 72 inch SID using the grid, IDQE vs. log air
kerma [mGy] at the image receptor........................................................................122
xiv
D-19 For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.
entrance skin exposure for newborn patients .........................................................123
D-20 Reduced AEC values For Newborn Patients For the Agfa CR system at a 40
inch SID without using the grid .............................................................................124
D-21 IDQE vs. entrance skin exposure for newborn patients for the Agfa CR
system at a 40 inch SID using the grid...................................................................125
D-22 Reduced AEC values for newborn patients for the Agfa CR system at a 40
inch SID using the grid...........................................................................................126
D-23 IDQE vs. entrance skin exposure for newborn patients for the Canon CR
system at a 40 inch SID using the grid...................................................................127
D-24 Reduced AEC values for newborn patients for the Canon CR system at a 40
inch SID using the grid...........................................................................................128
D-25 IDQE vs. entrance skin exposure for newborn patients for the Agfa CR
system at a 72 inch SID without using the grid......................................................129
D-26 Reduced AEC values for newborn patients for the Agfa CR system at a 72
inch SID without using the grid .............................................................................130
D-27 IDQE vs. entrance skin exposure for newborn patients For the Agfa CR
system at a 72 inch SID using the grid...................................................................131
D-28 Reduced AEC values for newborn patients for the Agfa CR system at a 72
inch SID using the grid...........................................................................................132
D-29 IDQE vs. entrance skin exposure for newborn patients for the Canon DR
system at a 72 inch SID using the grid...................................................................133
D-30 Reduced AEC values for newborn patients for the Canon DR system at a 72
inch SID using the grid...........................................................................................134
D-31 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 40 inch SID without using the grid......................................................135
D-32 Reduced AEC vs. entrance skin exposure values for one year old patients
for the Agfa CR system at a 40 inch SID without using the grid...........................136
D-33 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 40 inch SID using the grid...................................................................137
D-34 Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 40 inch SID using the grid ........................................138
xv
D-35 IDQE vs. entrance skin exposure for one year old patients for the Canon
CR system at a 40 inch SID using the grid ............................................................139
D-36 Reduced AEC values vs. entrance skin exposure for one year old patients
for the Canon CR system at a 40 inch SID using the grid .....................................140
D-37 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID without using the grid......................................................141
D-38 Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 72 inch SID without using the grid...........................142
D-39 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID using the grid...................................................................143
D-40 Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 72 inch SID using the grid ........................................144
D-41 IDQE vs. entrance skin exposure for one year old patients for the Canon
DR system at a 72 inch SID using the grid ............................................................145
D-42 Reduced AEC values vs. entrance skin exposure for one year old patients
for the Canon DR system at a 72 inch SID using the grid .....................................146
D-43 IDQE vs. effective dose for newborn patients for the Agfa CR system at a
40 inch SID without using the grid ........................................................................147
D-44 Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 40 inch SID without using the grid ...............................................148
D-45 IDQE vs. effective dose for newborn patients for the Agfa CR system at a
40 inch SID using the grid......................................................................................149
D-46 Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 40 inch SID using the grid ............................................................150
D-47 IDQE vs. effective dose for newborn patients for the Canon CR system at a
40 inch SID using the grid......................................................................................151
D-48 Reduced AEC values vs. effective dose for newborn patients for the Canon
CR system at a 40 inch SID using the grid ............................................................152
D-49 IDQE vs. effective dose for newborn patients for the Agfa CR system at a 72
inch SID without using the grid .............................................................................153
D-50 Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 72 inch SID without using the grid ...............................................154
xvi
D-51 IDQE vs. effective dose for newborn patients for the Agfa CR system at a
72 inch SID using the grid......................................................................................155
D-52 Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 72 inch SID using the grid ............................................................156
D-53 IDQE vs. effective dose for newborn patients for the Canon DR system at a
72 inch SID using the grid......................................................................................157
D-54 Reduced AEC values vs. effective dose for newborn patients for the Canon
DR system at a 72 inch SID using the grid ............................................................158
D-55 IDQE vs. effective dose for one year old patients for the Agfa CR system at
a 40 inch SID without using the grid......................................................................159
D-56 Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 40 inch SID without using the grid ......................................160
D-57 IDQE vs. effective dose for one year old patients for the Agfa CR system
at a 40 inch SID using the grid...............................................................................161
D-58 Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 40 inch SID using the grid ...................................................162
D-59 IDQE vs. entrance skin exposure for one year old patients for the Canon CR
system at a 40 inch SID using the grid...................................................................163
D-60 Reduced AEC values vs. effective dose for one year old patients for the
Canon CR system at a 40 inch SID using the grid .................................................164
D-61 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID without using the grid......................................................165
D-62 Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 72 inch SID without using the grid ......................................166
D-63 IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID using the grid...................................................................167
D-64 Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 72 inch SID using the grid ...................................................168
D-65 IDQE vs. entrance skin exposure for one year old patients for the Canon
DR system at a 72 inch SID using the grid ............................................................169
D-66 Reduced AEC values vs. effective dose for one year old patients for the
Canon DR system at a 72 inch SID using the grid.................................................170
G-1 Proper orientation of a CT phantom.......................................................................239
xvii
G-2 The CTP446 high resolution module. ....................................................................240
G-3 Orientation of a CT phantom for planar reconstructed images. .............................240
G-4 Planar reconstructed images...................................................................................241
xviii
Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
QUANTIFYING COMPUTED RADIOGRAPHY (CR) AND DIGITAL
RADIOGRAPHY (DR) IMAGE QUALITY AND PATIENT DOSE FOR PEDIATRIC
RADIOLOGY
By
Kennita A. Johnson
August 2003
Chair: David E. Hintenlang
Cochair: Manuel Arreola
Major Department: Biomedical Engineering
With the advent of digital imaging modalities, there is a potential for dose
reduction especially for pediatric patients due to the wide dynamic range and the image
processing capabilities of digital systems. A Canon digital radiography (DR) system and
an Agfa computed radiography (CR) system are currently in use at Shands Hospital at the
University of Florida. Using objective measures of image quality (modulation transfer
function (MTF), noise power spectrum (NPS), and integral detective quantum efficiency
(IDQE)), these systems can be evaluated and compared for pediatric chest imaging.
Using MIRD tissue-equivalent pediatric phantoms constructed at the University of
Florida, organ absorbed and effective doses of chest examinations can be measured.
With these measurements, a relationship between image quality and dose is used to
predict appropriate techniques used for pediatric chest imaging.
xix
The radiographic techniques developed in this research for the Agfa CR system
were identical to the radiographic techniques that a technologist would select for a patient
the same size and weight of the pediatric phantoms. The method for predicting
appropriate radiographic techniques is useful for setting up new systems such as the
Canon DR system at Shands at the University of Florida which is not used on patients
under 4 years of age. This research determined that the Canon DR system had superior
image quality, as measured by the IDQE, at lower doses than the Agfa CR system at
standard resolution.
xx
CHAPTER 1
INTRODUCTION
Children are more radiosensitive due to their rapidly dividing cells. Because of
their age, any radiation damage to cells would have a longer period of time to proliferate
over their lifetime (NCRP 1987). As a human grows from an infant to an adult, the tissue
composition, individual organ sizes and whole body size are continuously changing,
which are additional factors in the increased radiosensitivity of children (Johnson, 1998).
Frequently, effective doses for pediatric patients undergoing radiological examinations
are scaled from standard adult male phantom data. Simply scaling effective doses will
not accurately take into account the differences in tissue composition and patient size.
With the advances in technology and increased sensitivity in detectors, the potential for
better image quality at lower doses needs to be investigated.
Digital imaging has some similarities with conventional film-screen radiography.
They use the same x-ray tube and generator system for exposing the patient, which means
the technologist selects the same parameters such as peak tube potential, tube current and
exposure time (Fauber, 2000). But digital imaging overcomes some of the limitations of
screen-film radiography, which will be discussed in the next section. To take advantage
of these digital systems, the appropriate radiographic techniques are necessary. The
appropriate radiographic techniques will take into account both image quality and patient
dose.
Image quality measurements can be either subjective or objective. Subjective
image quality measurements can vary from observer to observer and could also involve
1
2
added exposure to patients. Objective measures are more reliable for an initial
assessment of image quality and comparing different systems. These measurements can
be used to determine the characteristics of the imaging systems, which would help in
optimizing dose before observer studies involving human subjects are conducted.
Modulation Transfer Function (MTF), Noise Power Spectrum (NPS), and Detective
Quantum Efficiency (DQE) along with doses measured using pediatric-sized phantoms,
can optimize radiographic techniques for computed radiography (CR) and digital
radiography (DR).
Digital Imaging Basics
There are certain properties that all digital imaging systems have in common
regardless of the image receptor. Digital images are defined as an image constructed
from numerical data in a two-dimensional array and are discrete in two respects. The
image is discrete with respect to its spatial organization. A digital image is made up of a
matrix of numbers, with the pixel being the smallest component. Many investigators
believe that a matrix size of 2048 x 2048 pixels is required for chest radiography. Once
the x-rays strike the detector, the analog signal from the detector is transformed into a
digital signal by an analog-to-digital converter (ADC). The digital signal is sent to a
computer or digital image processor which can analyze, transform or display the image.
The digital image is then stored in an archive (Hasegawa, 1991).
The most practical advantage of digital imaging is the wide dynamic range of
digital systems. Over a wide range of exposures, a diagnostically useful image can be
produced. This reduces the occurrence of and retakes for over- and underexposed images.
One reason for the wide dynamic range is the sensitivity of the detectors which can detect
at lower exposures than conventional film. Since the detectors are sensitive to lower
3
exposures, there is a possibility of dose reduction. The second reason for wide dynamic
Intensity or Count
range is processing of the image after it is formed.
0
Black
Pixel Value
4096
White
Figure 1-1. Histogram showing the number of each pixel values in an image.
Image Processing
When a patient image is taken, there are several pieces of information needed to
complete the image. First the patient information is entered, to associate the image with
the correct person. Next, a reference for the body part being imaged is entered. It helps to
identify what is on the image and it allows the image processing system to predict what
the histogram might look like and selection of the appropriate processing algorithm. The
histogram is a graphic display of the distribution of pixel values as shown in Figure 1-1.
The pixel values are represented by the horizontal axis and the total number of pixels at
each value is reflected on the vertical axis. Processing algorithms or mathematical
formulas are used to manipulate the histogram for a specific type of examination such as
chest, abdomen, or extremities (Fauber, 2000). This helps to properly display the image
on the computer monitor and helps to enhance the anatomical details important in
4
diagnosing the patient. One such algorithm is the translation from digital image value to
image brightness, which is performed through a look-up table (LUT). The LUT relates a
digital image value to a specific brightness level. The operator controls the contents of
the LUT by adjusting the window of the image display (Hasegawa, 1991). Figure 1-2a
shows how subjects imaged are mapped to image brightness. By narrowing the window
(Figure 1-2b), or the part of the image displayed, the image contrast can be increased.
There are additional processing algorithms that allow image subtraction, edge
enhancement, contrast enhancement or noise suppression (Fauber, 2000).
Subject
Air
Image Brightness
Black
Fat
Water
Muscle
Bone
Subject
Air
Image Brightness
Black
Fat
Water
Muscle
White
Bone
White
Figure 1-2. Mapping image brightness A) The LUT maps the subjects to image
brightness. B) A narrow window increases contrast.
Picture Archiving and Communications Systems (PACS)
Picture archiving and communication system (PACS) is a system for circulating
and storing digital images. Images are stored in a DICOM standard. DICOM stands for
Digital Imaging and Communication in Medicine and is an initiative sponsored by the
5
Radiological Society of North America and the Health and Management Systems
Society. The aim of the initiative is to integrate information and management systems so
that clinical information can be communicated among all specialties and providers. It
allows for patient and examination information to be stored along with the image. Major
manufacturers have agreed to this standard so that different systems can communicate
with each other.
Networking allows for the rapid transfer of information between computers. The
network consists of a digital imaging system, the workstations or viewing monitors, and
the archive or storage system. Once the images are produced with the digital imaging
system, the images are sent over the network to the workstations or the archive. Images
are displayed on workstations where the doctors can view and manipulate the images.
Images can be viewed at two sites simultaneously if doctors need to consult with each
other. Once stored, they can be sent to different parts of the hospital or archived for future
use (Gunn, 2002) which is one advantage of the PACS. It takes a few seconds to a few
minutes to bring images from the archive. Although the initial startup cost of a digital
imaging system and PACS is expensive, the long term cost of film and processing
chemicals is saved.
Computed Radiography
Computed radiography (CR) was introduced by FUJIFILM Medical systems USA,
Inc. in 1981. CR uses cassettes with a reusable image receptor, made of
photostimulatable phosphor screen. The screen is composed of a crystalline solid. In a
solid, there are discrete energy levels or bands that electrons in the atoms can occupy.
The valance band contains valence electrons, which lie in the outermost shell of the atom.
In the forbidden band, there are no permitted energy levels in pure materials. Electrons
6
can only pass through this band moving from the valence to the conduction band. In the
conduction band, the electrons have sufficient energy to move freely through the
crystalline lattice and in particular, to conduct electricity.
Conduction Band
Laser
Photon
Recombination
light
Electron Traps
X-Ray
Quantum
Valence Band
Electron
Hole
Figure 1-3. Phosphorescence process in CR plates
Imperfections, impurities and dopants provide additional energy levels in the
forbidden band. The phenomenon of phosphorescence depends on the presence of traps
in the forbidden band. The electron traps are normally empty. X-ray interactions
stimulate transitions from the valence band to the conduction band, then these electrons
fall into the traps rather than back into the valence band. These excited electrons fall into
electron traps were they can remain stable for days or even weeks. When stimulated by
light of a certain wavelength, the electron is lifted out of the electron trap back into the
conduction band. Some electrons fall back into traps but others fall to lower energy
levels and emit light (recombination light). This phenomenon is illustrated in Figure 1-3
(Krestel, 1990, Dendy 1999).
7
The imaging plate is constructed of many layers. The active layer where the
phosphorescence takes place is composed of europium-activated barium fluoride bromide
(BaSrFBrI:Eu). The europium is the dopant that provides the electron traps in the
forbidden layer. The phosphor emission of BaSrFBrI:Eu is in the vicinity of 400 nm.
Figure 1-4 shows a typical Agfa CR cassette and a cross section of the imaging plate.
The structure of the imaging plate (Gunn, 2002) is as follows:
1.
2.
3.
4.
5.
Protective layer – thin, transparent film to protect the plate.
Phosphor layer – composed of BaSrFBrI:Eu.
Conductive layer – composed of conductive crystals in a binder. Its function is to
reduce problems caused by electrostatic charges but in addition it absorbs light and
therefore increases image sharpness.
Support (base) – this acts as a support for the other layers and is made of polyester.
Laminate - composed of carbon particles in a binder and its function is to prevent
light leaking from the backing area
Protective Coat
Phosphor Layer
Conductive Layer
Support Layer
Laminate
Figure 1-4. The Agfa CR system cassette A) holder and B) the image plate structure
Once the cassette is exposed, it is taken to a “read-out” station or laser scanner.
Inside the machine, the cassette is opened and the phosphor screen is taken out. The
8
scanning laser beam, usually a helium-neon laser of wavelength 633 nm, scans the screen
line by line. This scanning produces the recombination light as shown in Figure 1-3 and
this light is captured by photomuliplier tubes (PMT) and converted to a digital signal as
shown in Figure 1-5. The amount of light collected by the PMT can be adjusted for high
or low x-ray exposures by changing the gain of the PMT. The fiber optic pickup guides
are immediately adjacent to both sides of the laser scan line to capture the emitted light as
efficiently as possible. The fiber optic pickup guides focus the light on a PMT after it is
filtered to remove any of the scattered stimulated light. Once the signal is amplified and
digitized, the patient image can be displayed on a monitor. After the laser scanning, the
screen is subject to an intense white light to clear all the remaining traps and the screen is
placed back into the cassette. The cassette is ready to use again (Krestel, 1999, Hendee,
1993).
Laser
Laser beam
Galvo
Photodetector
Fiber Optic
Phosphor Image Plate
Figure 1-5. The Agfa CR scanning procedure A) process inside the scanner and B) Agfa
Compact CR reader
The pixel size for CR images is determined by the reader sampling frequency.
Each cassette is initialized to standard or high resolution. The Agfa ADC Compact
9
reader has a standard resolution reading sampling frequency of 6 pixels/mm and a high
resolution sampling frequency of 9 pixels/mm. The newer Compact Plus reader has a
high resolution sampling frequency of 10 pixels/mm. This research used a 35 cm x 43 cm
(14 inch x 17 inch) cassette at standard resolution, which resulted in a pixel matrix of
2048 x 2494. The actual pixel size is 0.17 mm x 0.17 mm.
Similar to conventional screen-film, the Agfa CR system has the ability to change
the exposure class or speed to compensate for over- and underexposed images. This also
allows for additional widening of the dynamic range of the digital system. Exposure
class is an arbitrary scale with the value 100 being the benchmark to which all other
exposure classes are compared. Table 1-1 shows the relationship between exposure class,
mAs and amount of exposure compared to 100 exposure class.
Table 1-1. Relationship between exposure class, mAs and exposure
Exposure Class
50 100 200 400 800
mAs required to produce the same density
200 100 50 25 12.5
Amount of exposure compared to 100 exposure class 2x
1
1/2 1/4 1/8
Conventional screen-film used optical density as a measure of film darkening.
Computed radiography systems have a similar system called exposure level. The Agfa
CR system measures exposure level using the Equation 1-1 where speed refers to
exposure class. The manufacturer suggests that the optimal exposure level for the Agfa
system is approximately 2.0. The exposure class can be adjusted to maintain an optimal
exposure level to compensate for more or less radiation.
Exposure Level = log (exposure) + log (speed/200) + 2.22
(1-1)
One of the disadvantages of CR is that the laser is susceptible to dust and vibration,
particularly as the laser beam transfer via the galvo. Additionally, disruptions in the
vertical movement of the plate by mechanical means through the reader can cause
10
artifacts. Since there is some mechanical wear on the plates as they move through the
reader, the phosphor coating on the plate could become damaged or scratched, causing
artifacts in the image (Gunn, 2002).
Digital Radiography
There are two types of digital radiography (DR): direct and indirect. The type to be
evaluated in this research is the indirect-conversion systems developed by Canon USA,
Inc. as shown in Figure 1-6. This system is based on thin-film transistor (TFT) arrays
consisting of amorphous silicon (a-Si) photodiodes and a gadolinium scintillator top
layer. When the x-rays strike the scintillator, visible light is emitted and converted to an
electrical charge by the photodiodes. The charge collected at each diode is converted to a
digital value by the underlying readout electronics (Chotas, 1999). This process is
illustrated in Figure 1-7.
Figure 1-6. The Canon DR System A) the Canon CR system chestboard and B) the
Canon CR system display
11
Figure 1-7. DR scintillation process
Amorphous silicon (a-Si) has been used in fax machines, scanners and solar energy
panels for more than a decade (Yamazaki, 1999). Its ample semiconductor properties
make it photoconductive in the visible spectral range and can be used as a field effect
transistor. Amorphous silicon is a direct band gap material and the thickness necessary to
detect visible light is less than 1 µm (Jing et al, 1996). Amorphous silicon responds to
light in the wavelength of 400 to 650 nm with its peak response at 550-600 nm. The
quantum efficiency, the ratio of input to output quanta, is 80-90% (Street and Wu, 1996).
One advantage of a-Si is its low deposition temperature (200 to 250 C), which allows for
a wide variety of materials that can be used for a substrate. It also has good stability
against radiation and is compatible with silicon process technology that makes it easy to
manufacture (Hoheisel et al, 1998). To convert the light photons into charges, the
detectors are made up of a-Si diodes 0.5 to 0.8 µm thick. Thin-film transistors (TFT) are
created on a flat large area substrate such as glass, metal or plastic. Uniform layers of
various materials are deposited on the substrate and discrete structures are created
through photolithographic and etching techniques (Antonuk, 1995).
Each pixel has its own capacitor that can store electric charges (Figure 1-8). This
capacitor is connected to one side of a TFT switch. (Yamada, 1999) Each pixel is
12
connected to a row line for driving voltages and to a column line for readout. The
electric charges are read out in parallel for each row (Spahn, 2000). The pixel size in
digital radiography should be in the range of 150µm to provide the clinician with image
resolution comparable to film-screen (Moy, 1999). The large area new metal-insulatorsemiconductor (MIS) sensor and TFT (LANMIT) was developed and manufactured by
Canon, which allows the photodetector and the TFT to be manufactured as one unit
(Yamazaki, 1999). Unlike the CR system, the pixel size of the DR system is fixed
because of the way the LANMIT is structured (Figure 1-8). With a pixel matrix of 2688
x 2688, the large imaging area of 17 inch x 17 inch results in a pixel size of 0.16 mm x
0.16 mm.
Along with the a-Si flat panel sensor, the Canon DR system consists of a touch
sensitive liquid crystal display (LCD) operation panel and a control computer. The LCD
operation panel provides image preview as well as all the setup for imaging technique,
patient demographics and image distribution. The control computer is responsible for
system management including image processing, temporary hard-disk storage, and
network image distribution.
The advantage of the DR system is the images are produced instantly after
exposure, approximately 3 seconds. There is no need for a separate reader or any other
separate equipment. The time it takes to place the cassette in the reader, and have the
plate go through the reading process is also saved. There are no mechanical movements
in the flat panel sensor so there is less chance of breakage. The disadvantage of the
Canon DR system is that it is stationary. With the CR system, the cassettes can be taken
to the bedside and back to the reader for portable examinations. If there are any
13
complications with the x-ray tube, the room is completely unusable. With the CR
system, there are multiple cassettes and several readers available in the event that one of
the components in the system was broken.
Switch
Driving
Voltage
PIXEL
Readout
Figure 1-8. DR pixel configuration
Computed Tomography
Computed tomography (CT) was conceptualized by Oldendorf in 1961, and
developed as an image modality by Hounsfield in 1973 (Kirks, 1991). CT is a
tomographic imaging technique that generates cross-sectional images in the axial plane.
Images are maps of the relative linear attenuation values of tissue. For a fixed x-ray
position, a fan beam is passed through the patient and measurements of transmitted x-ray
beam intensities are made by an array of detectors. The measured x-ray transmission
values are called projections. CT images are derived from mathematical analysis of
multiple projections.
14
Equal Scan Time
Single slice
helical
scanner
Figure 1-9. Single and multi-slice helical CT Scanners.
Multislice
helical scanner
The GE HiSpeed CT scanner introduced helical scanning. Instead of the tube
rotating around a stationary patient one section at a time, the table with the patient
simultaneously moves as the x-ray tube rotates around the patient, creating a spiral or
helical pattern. The next generation of scanners called “multi-slice CT” uses the same
helical scanning but there are several rows of detectors per slice. The Figure 1-9 shows
the difference between the single slice and multi-slice CT. The multi-slice CT has
improved image quality because it is able to take thinner slices over a larger area in a
shorter amount of time. Multi-slice CT has the ability to reconstruct slices ‘retroactively’
meaning that it can reconstruct images at thinner slice thicknesses without having to
rescan the patient. It also has the ability to produce planar images. Planar images are
reconstructed images in the planes perpendicular to the scanning direction as shown in
15
Figure 1-10. It was suggested that since CT can provide planar images in addition to the
cross-sectional images, CT would soon replace CR and DR as the only imaging modality.
Scanned plane
Reconstructed plane
Scanning direction
Figure 1-10. Imaged and reconstructed planes in multi-slice CT.
Image Quality
There are three important aspects of a medical image to convey clinically useful
information: contrast, spatial resolution and noise. These are the relevant determinants of
image quality.
Contrast
Radiographs are usually contrast limited. Contrast refers to the differences in the
level of brightness of parts of the image. Image contrast (Figure 1-11) is determined both
by the subject contrast produced by the body and the detector contrast of the imaging
system (Wolbarst, 2000). Subject contrast is defined as the absolute value of the
difference between the intensity of the x-ray beam passing through an object and the
surrounding tissue. Subject contrast depends on thickness of the object, density and
atomic number of material, tube potential (kVp) and filtration. In that list, the only
16
parameter that can be controlled by the technologist in image production is tube potential.
Subject contrast decreases with increasing tube potential. Higher kVp x-rays have
greater penetrating ability and the differences in absorption are smaller, i.e. there is more
compton than photoelectric interactions (Kelsey, 1985).
Pixel Value
∆D=D2-D1
D1
D2
Distance
Image Contrast = ∆D/D1
Figure 1-11. Image contrast.
Detector contrast refers to the ability of the detector to convert differences in
photon fluence across the x-ray field into differences in signal amplitude. Detector
contrast depends on the chemical composition of the detector materials, its thickness,
atomic number, electron density and the physical process by which the detector converts
the radiation signal to electronic signal. Digital detectors have a linear response across a
greater range of radiation exposure, five orders of magnitude or more. A linear response
gives a constant change in detector signal output with constant change in exposure input
(Hasegawa, 1991). The exposure response of a digital imaging system is a plot of the
resultant pixel value versus incident x-ray exposure (Figure 1-12). It is similar in concept
17
to the sensitometric response of a screen-film system and contains information on the
Detector Signal Output
sensitivity and dynamic range of the digital imaging system (Hendee, 1993).
10000
8000
6000
4000
2000
0
0
20
40
60
80
100
Input Exposure
Figure 1-12. Linear response of input exposure to pixel value.
Contrast resolution describes how large a contrast difference is required for two
areas to be reliably perceived as separate and is determined by the number of gray scale
steps or levels and the overall system noise. The word “bit” describes how computers
store and manipulate numbers. All computers deal with binary (on-off, yes-no) numbers
instead of the more familiar decimal numbers. Any decimal number can be expressed in
terms of its equivalent binary number. Each on-off condition or power of two is called a
bit (Kelsey, 1985). Typical medical images require 10 to 12 bits per pixel (Hasegawa,
1991). The number of bits (n) determines the number of gray levels (2n) shown in Table
1-2. For medical images, there are 10 to 12 bits per pixel. In the absence of noise, the
minimal detectable contrast level is one gray scale step (Kelsey, 1985). For examples, a
2 bit pixel has 4 gray levels. The minimal detectable contrast between each step is 25 %
or ¼. As the number of bits increases, it is hard to perceive differences in one gray level
18
with the naked eye. Humans have a range of fewer than 32 shades of gray (Fauber,
2000).
Table 1-2. Bits and gray level relationship
Bits
Gray Levels
2
4
3
8
4
16
5
32
6
64
7
128
8
256
9
512
10
1024
11
2048
12
4096
The ratio of the object contrast to the background noise is known as the signal-tonoise ratio (SNR) (Kelsey, 1985). Since the noise specifies the uncertainty in the signal, it
is usually helpful to relate the noise to the signal size (Hasegawa, 1991). Since digital
images are represented with gray levels, the uncertainty or noise (σg) can be expressed as
Equation 1-2, where g is the gray level of the pixel, G is the total number of gray levels
and N is the number of photons per pixel required to give the brightest (highest) gray
level. The SNR decreases with an increasing number of gray levels unless the number of
photons also increases (Kelsey, 1985).
σg = g×
N
G
(1-2)
Spatial Resolution
Spatial resolution describes how close together two objects can be and still be
recognized as separate objects (Figure 1-13). Spatial resolution is measured in pixel size
or in line pairs per mm (lp/mm). Pixel size is determined by dividing the size of the
image in millimeters by the size of the matrix used to produce the image. A line pair
19
consists of one bright and one dark line. At least 2 pixels are required to display one line
pair. The maximum line pair resolution can be calculated by (1/2)x(1/pixel size). The
resolution of an imaging system can be measured by a line pair phantom (Figure 1-14)
whose lines are varying distances apart. Lines are formed by alternating attenuating
materials, with non attenuating materials or air. The limiting resolution is measure by the
highest number line pairs per millimeter can be seen as separate lines (Kelsey, 1985).
The requirements for spatial resolution depend on what the radiologist wants to see.
Resolution requirements for different body parts are listed in table 1-3.
Table 1-3. Resolution requirements (Hoheisel and Batz, 2000).
Body Part
Resolution
Soft Tissue
1-2 lp/mm
Fine bone structure
>3 lp/mm
Mammography
>5 lp/mm
Objects in
Body
Barely Resolved
Unresolved
Objects in
Image
Figure 1-13. Resolution of objects located in close proximity (Wolbarst, A.B, 1993).
Figure 1-14. Example of a line pair phantom.
20
Noise
Noise is defined as the uncertainty in a signal due to random fluctuations in that
signal. The principle source of noise are quantum noise cause by x-ray input fluctuations,
electronic noise and the quantization of noise from the analog-to-digital converter. The
number of photons emitted from the source per unit time varies according to a poisson
distribution. Other souces of random fluctuation are introduced by the process of
attenuation in the materials present in the path of the radiation beam (patient, x-ray beam
filtration, patient table, cassette) which also is a poisson process (Hasegawa, 1991).
Medical radiographs are often noise-limited, meaning at the contrast levels
obtained in radiographs, the ability to discern objects of interest is limited by the presence
of noise (Hasegawa, 1991). In radiology, because of the use of ionizing radiation, to
minimize radiation exposure, image noise should be dominated by quantum noise or dose
(Kelsey 1985, Hasegawa 1991).
If the image is not quantum noise limited, extra
exposure is given to the patient with no return in additional diagnostic information. If the
image is limited by electronic or noise other than photon quanta, the system was not
designed correctly (Hasegawa, 1991).
There are two sources of noise present in CR imaging, quantum noise and system
noise. Quantum mottle is the primary source of noise in CR. It is visible as density
fluctuations on the image. The fewer photons reaching the imaging plate to form the
image the greater the quantum mottle visible on the digital image. System noise results
from the image acquisition, phosphor conversion fluctuations, laser beam scanning, the
ADC and the mechanics of moving the plates in the reader. This type of noise is more
structured and obvious in an image. For instance, if there is a mechanical problem
moving the plate in the reader, this can show up as jitter on the image. Image noise can
21
be exaggerated by the postprocessing (contrast and edge enhancement) of the image
(Fauber, 2000).
Electronic noise can also come from the pixel reset, leakage currents, line
resistances, readout amplifiers and a non-ideal analog-to-digital converter. (Hoheisel and
Batz, 2000). There are three main sources of noise in digital radiography: the kTC noise
of the pixel TFT, readout amplifier input noise and voltage fluctuations on the bias and
gate connections. The kTC noise of the pixels TFT is the fluctuation of the charge stored
on capacitance C by a rise in temperature T multiplied by Boltzmann’s constant k and is a
very small contribution to the total noise. The readout amplifier noise is proportional to
the data line capacitance, which is proportional to the total number of pixels on the data
line. The larger-format, higher resolution systems tend to have greater noise. The noise
from the power supply voltage fluctuations of the bias and gate connections is also
coupled to the data line since the image receptors sense the signal on all line
simultaneously. This noise is visually more objectionable than random pixel noise
(Street et al, 1998).
Image Quality Measurements
Image quality measurements can be either subjective or objective. Subjective
measurements can vary from observer to observer. Objective measures are more reliable
for an initial assessment of image quality and comparing different systems. These
measurements can help to determine the characteristics of the imaging systems, which
would help in optimizing dose before observer studies involving human subjects are
conducted.
Digital imaging systems should be linear and shift invariant. If G is an object and B
is the image of that object, the equation B=A(G) shows mathematically how an image of
22
object G is created. The linear condition states that for every real number and α ≥0,
A(αG)=αA(G). This means that an object Ĝ is α times as bright as a given object G, its
image A(Ĝ) should be α times as bright as A(G). The shift invariant condition states that
if an object G is shifted in the object plane, it must also shift the same way in the image
plane. Mathematically, two objects G1 and G2, which are superimposed in the object
plane, the image A(G1+G2) is produced as the superimposition of the images A(G1) and
A(G2), it is expressed as A(G1+G2)=A(G1) + A(G2). (Krestel, 1990). This linear, shift
invariant condition is necessary in order to establish a relationship between the spatial
domain and the frequency domain. This connection can be established with the Fourier
transform.
In 1815, Jean-Baptiste-Joseph Fourier demonstrated that just about any function or
curve can be represented as a combination of sine and cosine functions of the appropriate
frequencies and amplitudes. An image can be expressed as a Fourier combination of sine
waves of different spatial frequencies, amplitudes and phases. The Fourier algorithm
transforms the image from the spatial domain to the frequency domain. Fourier
decomposition can be done using the fast Fourier transform algorithm of a computer
program such as Matlab (Wolbarst, 2000). Fourier transforms become important when
determining the MTF and NPS.
Modulation Transfer Function
Transfer Theory is used to describe the relationship between the input and output of
the system. The system in this case is the CR or DR system, the input would be x-ray
quanta and the output would be the image. In this situation, the imaging system can be
simply treated as a “blackbox” as seen in Figure 1-15, since it does not matter how the
output is generated from the input. The object of transfer theory is to determine the
23
transfer characteristics which allow the calculation of the output given the input of the
system. (Evans, 1981).
Input
Imaging
system
Output
Transfer
Characteristics
Figure 1-15. Transfer characteristics
In an ideal system, the radiation quanta from a point in the object plane should
produce an equivalent point in the image plane. But, because most imaging systems are
not ideal, a point in the object plane is often spread over an area in the image plane or
blurred. The point in the object plane can be represented mathematically by a delta
function as shown in Figure 1-16. The point spread function (PSF) helps to connect the
coordinates of the object in the object plane with the coordinates of the resultant image in
the image plane (Kelsey, 1985). The PSF is the image obtained from an infinitesimal
point object (Hasegawa, 1991). If the object plane contains a number of delta function
sources, each source will be imaged independently of the others and the resultant
intensity distribution in the image plane will be the sum of these delta functions. If the
delta function retains its shape irrespective of the position of the object in the object
plane, the system is shift invariant. Mathematically, the output is the convolution of the
input with the point spread function (Evans, 1981). The practical usefulness of the PSF is
limited due to the difficulty of its experimental measurements. A line spread function
(LSF) which is the intensity distribution of the image of an infinitely long and infinitely
24
narrow line of unit intensity. Practically, a LSF can be obtained by imaging a slit or wire
(Kelsey, 1985).
Since any function can be described by sine or cosine functions, the PSF or LSF
can be described in that manner. The Fourier transform can be used to deconvolve these
signals. By transforming the input function into the frequency domain, the output can be
derived by a simple line multiplication instead of the convolution required in the spatial
domain which can be quite difficult to calculate as seen in Equation 1-3.
∞ ∞
F (u, v) =
∫ ∫ f ( x , y ) exp[−2π i (ux + uy)]dxdy
1
1
(1-3)
− ∞− ∞
Point or
delta
function
Line
Input
Output
Figure 1-16. Point and line spread functions
Modulation is defined as the ratio of the amplitude of the signal to the average
value of the signal. The modulation transfer function (MTF) is computed by taking the
Fourier transform of the LSF. Equation 1-4 describes the MTF mathematically where
L(x,y) is the LSF. Figure 1-17 describes the relationship between the LSF and MTF.
25
By comparing the modulations of the input and output, information about the amount of
detail or resolution as a function of frequency can be determined for a given system. The
output image depends not only on the object being imaged but on the imaging system
used. Because the imaging system is made up of a sequence of components or imaging
chain, the output from one component becomes the input to the next component. It is
possible, although difficult, to measure the MTF of individual imaging system
components (Kelsey, 1985). Some degree of blur or unsharpness is added during the
image capture process in the real world. For instance, the readout of a CR storage
phosphor plate involves a laser beam of finite size scanning in one direction while the
plate is translated perpendicularly to the scan direction. Light diffusion in the phosphor
screens is a major contributor to MTF degradation. This results in a broadening of the
LSF and a fall off in MTF response with increasing spatial frequency. The greater the
degree of blur, the broader the output LSF and the more rapidly the resultant MTF falls
off with increasing spatial frequency. (Hendee, 1993).
∞ ∞
MTF (u, v) =
∫ ∫ L( x, y) exp[−2π i (ux + uy)]dxdy
(1-4)
− ∞− ∞
The spatial resolution response of an image capture process is best described by its
MTF. The MTF relates the input subject contrast to imaged subject contrast as a function
of spatial frequency. Smaller imaged objects have higher spatial frequencies while larger
objects have low spatial frequencies as shown in Figure 1-15. Larger objects with gradual
borders are comprised of mostly lower spatial frequencies, and smaller objects with sharp
borders have significant high spatial frequency content (Hendee, 1993). The imaging
system may be able to faithfully reproduce the large (low frequency) parts of the object
but may not be able to reproduce the fine detail (high spatial frequency) parts of the
26
object (Kelsey, 1985). The LSF must be sampled at discrete intervals in order to enter the
data into the computer. Since the function is sampled at intervals δx over the range m, the
transform can be calculated at intervals of δu=1/m, up to a frequency of umax=1/2δx. The
maximum umax is called the Nyquist frequency.
Modulation Transfer Function
Response
Pixel Value
Line Spread Function
(B)
Spatial Frequency
Response
Pixel Value
Position
Spatial Frequency
Response
Pixel Value
Position
(A)
Position
(C)
Spatial Frequency
Figure 1-17. MTF response from LSF input.
Limiting spatial resolution is often used to describe image receptor or system
performance. Limiting spatial resolution is determined with a lead bar test pattern as
shown previously in Figure 1-14, imaged at a low x-ray potential. When the image is
viewed, the highest number of line pairs per unit distance (lp/mm) that can be visualized
is the limiting spatial resolution. This is a subjective test. The limiting resolution can also
be determined objectively as the spatial frequency where the MTF response has dropped
to approximately 0.04 (Hendee, 1993).
27
Noise Power Spectrum
The Noise Power Spectrum (NPS) is a measure of the noise at each spatial
frequency and is defined as the Fourier transform of the autocorrelation function of a flat
field image (Evans, 1981). The autocorrelation function is a mathematical description of
how a function correlates with itself. The autocorrelation function is calculated by
averaging a large number of functions generated by shifting the density function
incrementally, multiplying it by the unshifted density function and integrating the product
(Hasegawa, 1991). Equation 1-5 states the NPS mathematically where ∆D(x,y) is the
density difference and X and Y are the pixel size (Evans, 1981). For square pixels, X=Y.
1 1
NPS (u , v) = lim
X ,Y →∞ 2 X 2Y
X
∫ ∫
Y
− X −Y
2
∆D( x, y ) × exp[−2π i (ux + uy )]dxdy
(1-5)
Figure 1-18. Two-Dimensional NPS of a flat field image
In practice, to calculate the NPS, first obtain a flat field image, which is an image
with no object between the x-ray source and the image receptor. Ideally, the resulting
image should be uniform. Density measurements taken across the image will have
variations due to nonuniformities in the image receptor and the inherent statistical
28
fluctuations in the x-ray beam. The flat field image is then divided into equal parts and
the fast Fourier transform is taken of each part. The Fourier amplitudes of each part are
averaged together and normalized by the pixel size of the image receptor. The resultant
two-dimensional NPS is shown in Figure 1-18. A slice of this two-dimensional NPS
adjacent to the axis gives a one-dimensional curve.
The area under the NPS curve gives
an estimation of the quantum mottle and system noise. The “ideal” noise value for a
system would be equal to the x-ray quantum noise, that is, no additional noise introduced
by the imaging system (Hoheisel and Batz, 2000).
Detective Quantum Efficiency
The Detective Quantum Efficiency (DQE) of an x-ray image receptor is a measure
of its efficiency in detecting x-rays referenced against an ideal detector. This concept is
illustrated in Equation 1-6. An ideal detector, by definition, has an absorption efficiency
of 100% and does not add any noise in the detection and signal conversion process
(Hendee, 1993). An ideal detector extracts all the information in the beam, i.e., if
SNRout=SNRideal then the maximum value of the DQE is equal to one (Sandborg and
Carlsson, 1992). The DQE is an objective measure and can be used to compare systems.
2
2
SNRout
SNRout
DQE =
=
2
2
SNRin
SNRideal
(1-6)
Over the last decade, the evaluation of imaging systems has become more elaborate
as the science of imaging systems has advanced. The characterization of imaging
systems performance in the research sector often includes the calculation of DQE as a
function of frequency, DQE(f). The DQE(f) is calculated from experimentally
determined modulation transfer function, MTF(f) and noise power spectrum, NPS(f)
29
using the relationship established in Equation 1-7 (Boone and Seibert, 1997). The MTF is
an estimation of the signal and the NPS and q is the estimation of the noise. The factor q
(units mm-2 mGy-1) is the square of the signal-to-noise ratio of the incident x-ray beam
energy (E) spectrum as seen in Equation 1-8. This can be calculated using computer
simulation programs. The factor k is the conversion from pixel value to exposure. The
factor k can be removed from the equation if pixel values are converted to exposure prior
to determination of MTF and NPS.
k ⋅ [MTF ( f ) ]
DQE ( f ) =
q ⋅ NPS ( f )
2
(∫ q ( E ) EdE )
(1-7)
2
q =
∫ q(E )E
2
dE
f Nyquist
IDQE
=
(1-8)
∫ 2π f
⋅ DQE ( f ) df
(1-9)
0
When comparing image quality at different techniques or from different systems,
the frequency component of the DQE may not be as important as the image quality of the
whole image. The Integral DQE (IDQE), as shown in Equation 1-9, gives a single unit
descriptor of image quality. The IDQE will increase for systems with greater quantum
efficiency as well as for higher system Nyquist frequency (Fetterly, 2000). Figure 1-19
shows the quantum efficiency for materials typically used in digital imaging. Barium is
used in CR plates and gadolinium is used in DR scintillators. There is a peak in the
quantum efficiency spectrum at the k-edge. For barium, the k-edge corresponds with the
mean energy of the photons in the diagnostic energy range. This matching of energies
makes barium ideal for diagnostic medical imaging.
Quantum Efficiency
30
k edge
Barium
Gadolinium
0
10
20
30
40
50
60
70
80
90
100
Energy (kVp)
Figure 1-19. Quantum efficiency of materials typically used in digital images
Patient Dose
Absorbed dose is a measure of energy deposited per unit mass and provides a
means to gauge the potential for biological effect. Absorbed dose is measured in gray,
which is equivalent to the energy deposition of one joule per kilogram of tissue. Organ
dose refers to the radiation-absorbed dose delivered to the organs of a patient during a
radiologic examination. The risks to humans from radiation exposure from a diagnostic
procedure can be described by the effective dose (ICRP 1990) or the effective dose
equivalent (ICRP 1977). Since radiation exposure in diagnostic radiology is nonuniform,
effective dose can be thought of as the uniform whole body dose that has the same
radiation risk as the nonuniform dose (Huda and Slone, 1995). Effective dose (E) takes
into account the absorbed dose (D), the quality of the radiation particles (wR) and the
31
relative risk of developing cancer and radiosensitivity of the tissues (wT). The tissue
weighting factors are a ratio of the stochastic effects in a particular tissue or organ to the
total risk when the whole body is uniformly irradiated (ICRP 1990). Tissue weighting
factors are based on relative risk and cancer treatment options at a particular time in
history and are subject to change.
Now, there is a push to move from an older quality factor Q to a new radiation
weighting factor, wr. Equations 1-10 and 1-11 show how effective dose (E) and effective
dose equivalent (HE) is calculated from absorbed dose (D), radiation quality factor (Q or
wr) and the tissue weighting factors (wt).
H E (mSv) = D(mGy) * Q * wt ,ICRP 26
(1-10)
E (mSv) = D(mGy ) * wr * wt , ICRP 60
(1-11)
Image Quality, Dose and Radiographic Technique
The technologist is responsible for taking the medical image. The technologist has
several parameters that they can control to take a medical image. Each of these
parameters has an effect on image quality and change depending on the patient. The
parameters that the technologist can control include: peak tube potential (kVp), tube
current and time (mAs), source-to-image receptor distance, focal spot size and use of
grid. Choosing the proper radiographic techniques, the best image quality at the lowest
dose necessary to produce a diagnostically useful image can be achieved. Equipment
options, which can have an effect on patient dose, fall in two categories:
1.
2.
Those that have little influence on image quality. An example would be the use of
low attenuation materials between the patient and the image receptor such as
patient support pads.
Those that involve a trade-off between image quality and patient dose i.e., changes
in radiation quality, photon fluence and removal of scattered radiation. (Martin et.
al., 1999 )
32
Radiation quality refers to a combination of beam energy and filtration. The beam
energy is determined by the peak kilovoltage (kVp), which is selected for each
examination depending on the part of the body imaged, the size of the patient, the type of
information required, and the display method (Martin et. al., 1999). To create an
acceptable image, the amount of radiation needed to penetrate a patient increases with
patient thickness. A selection of a higher kVp will raise the average beam energy and
increase the beam penetrability. The entrance skin exposure will change with the square
of the change in kVp. The lower energy photons only contribute to patient dose since
they are not able to penetrate the patient to help form the image. Since, the x-ray beam
from diagnostic x-ray tubes is a spectrum of energies, the filtration serves to eliminate the
lower energy photons. Inherent filtration comes from tube housing and additional
filtration can be sheets of aluminum or copper (Parry et al 1999). Subject contrast
decreases with increasing tube potential because of the increase in Compton scatter and
decrease of photoelectric absorption. It also increases the radiographic density of the
image because higher kV photons can penetrate tissues and cause images to be too dark.
There may be less of a density difference between different anatomical regions if the
image is too dark (Kelsey, 1985, Fauber, 2000). Also, the increase in scatter will increase
the amount of noise, which does not offer any additional information in the image.
Tube current, measured in milliamps, gives an estimate of the number of photons
used for an image. The exposure time, measured in seconds, determines how long the xray beam will be on. The two parameters can be multiplied together to form one unit
milliamperage-seconds or mAs. Tube current and exposure time have an inverse
relationship when maintaining a constant mAs. The number of photons used to create an
33
image has an effect on the image quality. As the mAs increases, the quantity of radiation
increases and radiographic density increases. Since the noise is proportional to the square
root of the number of photons used, increasing the number of photons reduces the noise
in the image. In theory, the exposure time should be as short as possible to eliminate
unsharpness caused by patient movement. Increasing the kV allows the tube current or
the exposure time to be reduced (Dendy, 1999).
The focal spot size selection determines the amount of detail or resolution that will
be seen on the image. The larger focal spot has a greater heat loading or can withstand
higher mAs values, while a smaller focal spot produces greater radiographic detail
(Kelsey, 1985). The source to image distance (SID), not only affects the geometric
distortion of the image but also the amount of radiation reaching the imaging plate. As
SID increases, radiographic density decreases as a result of the inverse square law.
Increasing the SID requires that mAs be increased to maintain the same density (Fauber,
2000).
Grids are used to reduce the scatter radiation that reaches the image receptor. This
helps to improve the contrast of the images. Grids must be used if scatter is significantly
reducing contrast when irradiating large volumes (Dendy, 1999). Grids absorb a portion
of the primary x-rays; therefore, the amount of radiation must be increased to achieve the
same exposure reaching the image receptor (Parry et al 1999). Use of grids requires an
increase in mAs, thus increasing patient dose. To lower the amount of exposure to the
patient, the air gap technique is used to reduce scatter in pediatric chest imaging. The gap
between the patient and the image receptor allows for more of the photons moving in the
forward direction and less of the scattered photons to hit the image receptor, giving an
34
improved image. With the air gap technique, there is not only a reduction in scatter but a
reduction in signal (Dendy, 1999).
There are many thousands of possible combinations of kVp, mA, SID, exposure
time, exposure class and grid ratios. When combined with patients of various sizes, and
various pathologic conditions, the selection of proper exposure factors becomes a
difficult task. Radiographic technique charts make setting radiographic technique factors
much more manageable for technologist. Automatic exposure control (AEC) is a system
used to consistently control radiographic density by terminating the length of exposure
based on the amount of radiation reaching the image receptor. Ionization chambers built
into the table are used to measure the amount of radiation reaching the image receptors
and maintain constant exposure level. With the AEC systems, the technologist selects the
kVp and mA. Once the ionization chambers have detected a certain amount of exposure,
the x-ray beam is teminated. Proper centering of the patient over the AEC chambers will
ensure the appropriate cut off time (Fauber, 2000). AEC systems are not typically used
on small children since they often do not cover all the chambers.
Summary
Image quality is to a large extent a descriptor of the subjective interpretation of
visual data. Image quality of a radiographic image may be defined as the ability of the
imaging system to record each point in an object as a point on the image receptor
(Kamm, 1997). Detective quantum efficiency (DQE) is generally accepted as the best
single objective indicator of image quality since it combines spatial resolution (i.e., MTF)
and image noise (i.e., NPS) to provide a measure of the signal-to-noise ratio of the
various frequency components of the image (Chotas, et al 1999). Combining image
quality measurements for different radiographic techniques with patient dose
35
considerations, the characteristics of digital imaging systems can be evaluated, optimized
and compared.
CHAPTER 2
HYPOTHESIS
The goal of this dissertation is to optimize the radiographic techniques used to
produce CR and DR pediatric chest images. By relating the image quality properties of
CR and DR to radiographic technique, air kerma at the image receptor, entrance skin
exposure and effective dose, the radiographic techniques can be optimized to produce the
best image quality at the lowest dose. Radiographic techniques include tube potential
(kVP), tube current and time (mAs), source-to-image receptor distance (SID) and grid
use. The effects of changing these parameters on image quality measurements, (the
modulation transfer function (MTF), the noise power spectrum (NPS) and integral
detective quantum efficiency (IDQE)) will determine the characteristics of the CR and
DR systems. Using pediatric anthropomorphic phantoms and MOSFET dosimeters, the
effective doses to pediatric patients are determined for the varying radiographic technique
parameters. By relating the IDQE to entrance skin exposure, a direct correlation between
image quality and radiographic technique is developed. This research will test the
following hypotheses:
Hypothesis 1. An increase in peak tube potential (kVp) will not change the MTF of
the CR or DR systems.
Hypothesis 2. The increase of tube current and time (mAs) will produce lower
NPS.
Hypothesis 3. The use of the grid during image production will produce higher
NPS than images taken without the grid.
36
37
Hypothesis 4. The use of a longer SID will produce higher NPS.
Hypothesis 5. IDQE will increase for lower tube potentials.
Hypothesis 6. DR will provide better image quality than CR with reduced doses for
pediatric patients.
Hypothesis 7. CR will provide better image quality than multi-slice CT used for
planar imaging for pediatric patients.
It was not possible to determine the outcome of Hypothesis 7. The CT phantom
available was not adequate to measure image quality of planar images from the multislice CT scanner. Appendix G explains the limitations of the CT phantom available.
Construction of a new, more appropriate CT phantom was beyond the scope of this
research.
The rationale behind Hypothesis 1 is that the MTF is the characterization of the
imaging system’s ability to transfer information from the input to the output. As a
measure of resolution, it is more a function of the pixel size of the image receptor than
the radiation input of the tube. Hypotheses 2, 3 and 4 are based on the principle that
more photons will produce less noise. Increasing mAs will produce more photons
reaching the imaging plate, while using a grid or increasing the SID will produce less
photons reaching the imaging plate. The basis for Hypothesis 5 is that IDQE increases
with quantum efficiency and quantum efficiency decreases with higher tube potentials.
The Gd2O2S:Tb screen used in the DR system has a higher quantum efficiency than the
BaSrFBrI:Eu used in the CR system. Also, the DR system has a smaller pixel size than
the CR plates at standard resolution. Therefore, Hypothesis 6 predicts that DR will
provide a better image quality that CR.
CHAPTER 3
LITERATURE REVIEW
With the advent of digital imaging, methods to determine the image quality of these
systems had to be developed. There have been several studies that compare the image
quality of digital systems with screen-film, the conventional method of producing
medical images. The potential for dose reduction, due to the wide latitude of digital
systems, was also investigated.
Droege and Morin (1982) developed a practical method of determining the MTF
from line pair phantoms. The MTF was determined by taking the standard deviation of
regions over the line pair groups. This method was originally developed for CT scanners
but can easily be adapted for projection radiography.
Giger and Doi (1984) determined the MTF from conventional radiographs that
were scanned and converted into digital form. They found that different algorithms
enhanced the resolution, and was able to show that image processing can produce MTFs
greater than one.
Hillen et al. (1987) evaluated the Fuji system for objective measures of image
quality and compared to screen-film systems. The MTF was determined from a periodic
bar phantom and the NPS was determined at 0.3 mR. The Fuji systems and the screenfilm systems had similar signal-to-noise ratios at lower frequencies. At higher
frequencies, the screen-film systems had superior image quality.
In 1991, Sanada et al. compared the image quality of the Toshiba CR system with
that of a screen-film system. The MTF was determined 10 µm slit device. The high
38
39
resolution plates have a significantly higher MTF than the plates at standard resolution.
The NPS of the CR system was much higher than that of the screen-film system.
Chotas et al. (1993) established a relationship between signal-to-noise ratio and
tube potential for a Philips CR system using a GE AMX portable x-ray tube. Signal-tonoise measurements were taken from regions on anthropomorphic and geometric chest
phantoms. In the lung regions, there was a degredation in signal-to-noise with increasing
kVp. In the mediastinium and subdiaphragm regions, the signal-to-noise was lower than
that of the lung and was consistent across the range of kVp. Dose measurements on the
phantoms at the different tube potentials helped to match patient risk with the signal-tonoise ratio.
Workman and Cowen, in 1993, measured the image quality properties of the third
generation of Fuji CR plates. The results show a significant improvement in signal-tonoise performance over previous versions of the system. Comparing these measurements
with rare-earth screen-film systems under identical conditions, the CR compared
favorably with the conventional system.
Dobbins et al. (1995) measured the MTF(f), NPS(f) and DQE(f) for four
generations of Philips CR plates and established methods of determining NPS for digital
systems. The NPS measurements prove that NPS decreases with higher exposures. The
MTF was determined using a slit device. There was a slight difference in MTF in the
scan and subscan directions. The newest models and high resolution plates proved to
have superior DQE.
In 1995, Boone and Seibert developed an algorithm to accurately estimate the
quantum fluence for a variety of x-ray beams or input signal to noise. The tungsten anode
40
spectral model interpolating polynomials (TASMIP) algorithm is based on measurements
of tube output (mR/mAs). A computer program was developed and made available on
the internet. The inputs to the computer program are kVp, tube ripple and inherent
filtration.
Kengyelics et al. (1998) evaluated the MTF(f), NPS(f), and DQE(f) of fifth
generation Phillips CR plates at different exposure/dose levels. The MTF was measured
using a narrow slit of 20 µm slit. The NPS was measured over a range of exposures from
0.3 to 80 µGy. The improved system gain proved to have a superior DQE than previous
versions.
Siewerdsen et al. (1998) examined the performance of a flat panel imager compose
of a-Si:H TFT. In this paper, theoretical calculations are compared to empirical x-ray
sensitivity, NPS and DQE. The NPS was determined for three different Gd2O2S:Tb
converters: Lanex Fast-B, Regular and Fine. The Lanex Fine had a very flat DQE
distribution and much lower than the Fast-B. This suggests that the fine converter
performs the same at high and low frequencies. They were able to get good agreement
with the theoretical calculations.
Strotzer et al. (1998) conducted a study to compare digital radiographs with
conventional film/screen. Images were taken of 120 patients with both film/screen and
using a silicon DR system. Six radiologists using a subjective five-point preference
scale, which rated underexposure, overexposure, contrast resolution, spatial resolution,
and soft-tissue representation, evaluated these images. Overall image quality was ranked
on a 10-point scale. It was found that digital images were nearly equivalent to screenfilm radiographs when the radiation exposure was reduced by 50%.
41
Lauders et al. (1998a) evaluated a selenium based digital chest radiography system.
The principal aim of the evaluation was to assess how the image quality and dose
compared to a conventional system. The physical measurements included radiation dose,
dynamic range, resolution, signal-to-noise ratio (DQE) and threshold contrast detail
detectability (TCDD). Radiologist in a 3-point scale evaluated PA chest examinations of
100 patients. Entrance surface dose (ESD) was measured using thermoluminsescent
dosimeters. An additional series of measurements were taken to establish a relationship
between ESD and kVp using an ionization chamber and an anthropomorphic chest
phantom. The DQE and TCDD response was measured for a range of exposure and kVp
values. A relationship was established between DQE and kVp. For the same kVp, the
selenium-based system had a higher DQE than screen-film.
Launders et al. (1998b) conducted another study comparing a selenium-based
system to phosphor-based systems. In this study, they evaluated field size and geometric
distortion, sensitometric response, MTF, DQE and TCDD. It was shown that the there
was a potential for radiation dose reduction due to the values of the dynamic range and
DQE at low spatial frequencies.
Bradford et al. (1999) evaluated the performance characteristics of different types
of Kodak CR plates and compared them to previously published results from the Fuji
system. The MTF was determined using narrow slit. The presampled MTFs of both
systems are very similar. The NPS was determined at 0.03, 0.3, 3.0 and 30.0 mR. The
NPS was 20% higher for the Kodak system at low exposure and 40%-70% higher at the
higher exposure levels. This corresponded to a 20%-50% lower DQE for Kodak.
42
In order to determine image quality from one image, Stierstorfer and Spahn (1999)
developed a self-normalizing method to determine the DQE. One image contains test
pattern and a large uniform image to measure MTF and NPS, respectively. They propose
this method is fast and can be used a daily routine.
Fetterly and Hangrandreou (2000) evaluated the image quality of the Lumisys
ACR-2000 and compared to the Fuji AC-3 CR system. The MTF was determined using
an edge device. The presampled MTF of the Fuji CR system is generally higher than that
of the Lumysis CR system. The NPS was taken at 0.1, 1.0 and 10 mR for 70 and 120
kVp beams. The 1D NPS of Lumysis CR system was greater than that of the Fuji CR
system. They also introduce the concept of the integral DQE. The DQE of the Lumisys
CR system was 30% lower than that of Fuji CR system. In 2001, Fetterly and
Hangrandreou went on to establish a relationship between x-ray spectra and DQE. They
measured DQE at 70, 95 and 120 kVp. They used various filters such as aluminum,
copper and “patient equivalent phantom” or PEP. They showed that there is a possibility
to degrade the MTF by measuring the MTF at 120 kVp using various thicknesses of PEP.
The degradation in the MTF was due to the energy deposition in the phosphor. Lower
energy photons deposit their energy near the surface of the phosphor providing the
greatest sharpness. By filtering the beam, the lower energy photons are taken away,
leaving only the photons that penetrate deeper into the phosphor, resulting in a lower
MTF. Noise increased with greater thickness of filtration. The IDQE decreased for all
tube potentials with increasing filter thickness, which one could extrapolate that image
quality is reduced with increasing patient thickness.
43
Floyd et al. (2001) determined the imaging characteristics of an amorphous silicon
(a-Si) flat panel detector for chest radiography. The MTF was determined with a 12 µm
and the NPS was determined using 0.5 mm of additional copper filtration at 70 kVp and
0.3 mR. The grid was removed from the flat panel detector before NPS measurements
were made. The DR system was compared to a CR system and the DR system was
determined to have a superior MTF and DQE to CR.
In 1991, Cohen et al. evaluated the effects of reduced dose on image quality of Fuji
CR system for neonatal chest images. The CR images were printed with a laser printer
and compared to screen-film images. For images taken at the same exposure as screenfilm, there is no loss in image quality. For a 50% reduction in radiation dose, there is a
detectable loss in image quality for the CR system.
Hufton et al. (1998) measured doses to 900 pediatric patients ages 0-15 years of
chest, abdomen, pelvis and skull examinations. Half of the patients were taken using the
Fuji CR system and the other half had images taken on conventional screen-film. Dose
measurements were taken with a dose-area product meter. Entrance skin exposure
measurements were determined by using the recorded exposure factors and the measured
tube output. Image quality was evaluated by six radiologist based on the Commission of
the European Communities (CEC) criteria which uses the visibility of anatomical
structures in clinical images as a standard. Hufton et al. found that by using CR instead of
600 speed screen/film system, doses could be reduced by 40% for abdomen, pelvis and
skull examinations. Further dose reduction could be achieved by using the CR as a 1000
speed system. Since most departments use 400 speed film/screen systems, it is estimated
44
that these departments could see a dose reduction of at least 60% for abdomen, pelvis and
skull examinations.
Comparisons between studies are difficult due to the differences in imaging
parameters, these studies have shown that it is possible to measure the image quality of
digital systems. Two of these studies prove that it is possible to find a relationship
between image quality and dose.
CHAPTER 4
MEAUREMENT OF IMAGE QUALITY
Introduction
Image quality is often a subjective measure of how much information is available
in an image. The radiologist sets the standard of image quality since the doctors are the
interpreters of the information presented in the image. By definition, subjective
measurements vary from person to person. This makes it difficult to objectively compare
the “image quality” obtained by different systems. Objective measures of image quality
do not change with individual perception and allow for the determination of system
characteristics. Since the DQE is generally considered to be the best overall descriptor of
image quality, the integral DQE (IDQE) provides a single unit descriptor of a system’s
image quality. Image quality is often measured for a standard configuration which may
not be an accurate depiction of radiographic techniques used for patient imaging.
Measuring a systems image quality at clinically relevant radiographic techniques permits
a characterization of the image quality across a broad range of clinical practice.
Materials and Methods
Software
MediSurf, a product of Algotech systems Ltd.1 provides a way to view and
manipulate images via the internet. Medisurf was cleared prior to market by the FDA
under 501(k). Images are viewed in full diagnostic quality using the DICOM-3 protocol
and can be saved on a local computer. Medisurf also has tools that allow window and
1
Algotec systems Ltd., 4 Hamelacha Street, PO Box 2408, Industrial Zone North, Raanana, Isreal
45
46
level manipulation, ROI measurements and annotations. ImageJ is a public domain Java
image processing program produced by the National Institutes of Health (NIH). It runs,
either as an online applet, or as a downloadable application, on any computer with a Java
1.1 or later virtual machine. Through the use of Java, users can create their own image
processing algorithms to manipulate images along with a library of algorithms already
available. ImageJ can be downloaded from http://rsb.info.nih.gov/ij/index.html.
MATLAB®, a product of Mathworks Inc.2, is a high-performance language for technical
computing. Matlab allows for complex image processing and manipulation such as fast
Fourier transforms.
Equipment
The CR and DR systems are installed in separate rooms in Shands Hospital at the
University of Florida. Both rooms use a Dunlee3 x-ray tube with a Picker4 VPE 3 phase
generator. The inherent filtration for the x-ray tube used with the CR is 2.2 mm Al
equivalent with a half value layer of 3.70 mm Al at 80 kVp. The inherent filtration for
the x-ray tube used with the DR is 2.7 mm Al equivalent with a half value layer of 3.88
mm Al at 80 kVp. Exposure measurements were made with the Radcal5 MDH ion
chamber. The exposures measured in mR were converted to air kerma [mGy] by
multiplying by 8.77x10-3.
2
The Mathworks, Inc., 3 Apple Hill Drive, Natick, MA 01760
3
Dunlee, 555 North Commerce Street, Aurora, Illinois 60504
4
Philips Medical Systems, 22100 Bothell Everett Highway, P.O. Box 3003, Bothell, WA 98041-3003
5
Radcal Corportation, 426 West Duarte Road, Monrovia, Ca 91016
47
The CR unit is the Agfa6 ADC system with a Compact reader and MD10 imaging
plates. For this experiment, the 14 inch x 17 inch cassettes at standard resolution were
used. The cassettes can be placed in the Bucky or placed on the tabletop. Agfa CR
system has an imaging depth of 12 bits which corresponds to 4096 gray levels. The
image matrix size for standard resolution is 2048 x 2494 which results in a 0.17mm x
0.17 mm pixel size for the 14 inch x 17 inch cassette at standard resolution. The Agfa
CR system also allows for change in exposure class or speed which expands the latitude
of the system when the examination information is entered and written to the plate.
The DR unit is the Canon7 CXDI-11 system has 17 inch x 17 inch flat panel
chestboard. The image matrix size is 2688 x 2688 which results in 0.16 mm x 0.16 mm
pixel size for the 17 inch x 17 inch field. The detector is amorphous silicon TFT with a
Gd2O2S:Tb screen. The grid is incorporated in the flat panel and cannot be easily
removed. The Canon CDXI-11 is considered a 200 speed system. It has an imaging
depth of 12 bits which corresponds to 4096 gray levels.
Modulation Transfer Function
Line pair phantom method
Droege and Morin (1982) developed a method to determine the MTF by taking the
standard deviation of pixel values within an image of a cyclic bar phantom. The Hüttner
phantom, a cyclic bar phantom as shown in Figure 4-1, has a frequency range of 0.5-5
lp/mm. The Hüttner phantom was placed in contact with the cassette for the Agfa CR
system and placed in contact with the chestboard for the Canon DR system. Images were
6
Agfa Corporation, 100 Challenger Road, Ridgefield Park, NJ 07660
7
Canon U.S.A., Inc., One Canon Plaza, Lake Success , NY , 11042
48
taken at 50-70 kVp, at 5 kVp intervals for each system. All of the images were processed
with a “flat field” algorithm. The images were retrieved from the PACS system and
Medisurf software was used to determine the mean and standard deviation of regions of
interest (ROI) over the line pair regions of the images. In Equation 4-1, the value M’ is
the standard deviation of a frequency region in the cyclic bar pattern can be corrected for
the noise. The noise, N as defined by Equation 4-2 is the standard deviation of the
uniform light (Nlight) and dark (Ndark) regions of the phantom. The Mo can be calculated
by using the mean values of the light (Mlight) and dark (Mdark) uniform regions of the
phantom as shown in Equation 4-3. Equation 4-4 evaluates the MTF for each line pair
group in the phantom. An example of this calculation can be found in Appendix A. The
MTF was normalized to the lowest frequency and plotted vs. frequency.
No
Pb
+0.5
Pb
0.63
0.56
0.5
0.9
0.8
0.71
1.25
1.12
1.0
1.8
1.6
1.4
2.5
2.24
2.0
3.55
3.15
2.8
5.0
4.5
4.0
Figure 4-1. Hüttner phantom A) Frequency configuration in lp/mm and B) image of
phantom
M=
N2 =
Mo =
(M ′
(N
2
2
Light
− N2
+N
)
2
Dark
)
2
M Light − M Dark
2
(4-1)
(4-2)
(4-3)
49
MTF ( f ) =
π 2 M(f )
⋅
M0
4
Line spread function method
(4-4)
The presampled MTF for both the Agfa CR system and the Canon DR systems was
initially performed with a slit camera but later was determined from a thin line contained
in the Leeds8 E1 phantom, shown in Figure 4-2. The slit camera was placed in a holder
and the holder was placed in contact with the cassette. The E1 phantom was placed in
contact with the cassette for the Agfa CR system or placed in contact with the chestboard
for the Canon DR system. The slit and the line of the E1 phantom was angled 2 degrees
off the vertical axis. For Agfa CR system, the vertical axis corresponds to the longer axis
of the 14 inch x 17 inch cassette. The images were taken for both systems at 40 inch
SID, 70 kVp and enough mAs to reach an air kerma of 0.0878 mGy measured using an
MDH ion chamber. A “flat field” algorithm was used to process the images on both
systems. The images were retrieved from the PACS archive and saved to the local hard
drive. The images were manipulated with Matlab and the code for performing the
transform to obtain the MTF is described in Appendix B. To get the line spread function
(LSF), ten profiles were taken perpendicular to the slit or line and normalize to the
maximum pixel value. Before the ten LSF could be averaged together, a correction had
to be made in order to align the maximum pixel values off set by the 2 degree
configuration of the line in the image. The Fourier transform of the LSF produced the
MTF. The MTF was the multiplied by 1/sinc(πυp) were υ is the frequency and p is the
pixel size. The MTF was normalized to the MTF at zero frequency and plotted versus
frequency.
8
Leeds Test Objects, Wetherby Road, Boroughbridge, North Yorkshire YO51 9UY, UK
50
Figure 4-2. Image of E1 Leeds Phantom
Noise Power Spectrum
The normalized noise power spectrum (NPS) was measured for different clinically
applicable configurations shown in Table 4-1. Prior to the NPS measurements, exposure
measurements were taken for each combination in Table 4-1 with an MDH ion chamber
on the table top, converted to air kerma and recorded. The image receptors were exposed
without any additional filtration in the kVp and mAs range in Table 4-1. For the Agfa
CR system, the exposure class was adjusted before the plates were placed in the reader in
order to maintain an exposure level of approximately 2.0. All images for both systems
were processed with a “flat field” algorithm. Images were retrieved from the PACS
system and saved to the local hard drive. Images were manipulated with Matlab and the
code for the NPS calculations can be found in Appendix B. Using Matlab, the center
1024x1024 region of interest (ROI) of each image was divided into sixty-four 128x128
nonoverlapping ROIs. The formula for determining the two-dimensional NPS is shown
in Equation 4-5 where <|FT(u,v)|2> is the ensemble average of the squares of the Fourier
amplitudes from all 64 ROIs, Nx and Ny are the number of elements in the discrete
transforms and ∆x and ∆y are the pixel sizes in x and y direction (Dobbins et al 1995).
51
NPS (u, v) =
FT (u, v)
NxNy
2
∆ x∆ y
(4-5)
The 1D NPS needed to calculate the DQE can be determined from a thick slice of
the 2D spectrum. A 4x128 slice is taken adjacent to the x-axis of the 2D NPS. The 1D
NPS values were plotted versus frequency up to the Nyquist frequency.
Table 4-1. Measurement configurations for Agfa CR system and Canon DR system
Radiography system Grid Use
SID
kVp Range
mAs
Range
No Grid
40
50-70, 5 kV intervals
0.6-40
72
70-85, 5 kV intervals
0.6-20
Agfa CR system
Grid
40
50-70, 5 kV intervals
0.6-40
72
70-85, 5 kV intervals
0.6-20
Grid
40
50-70, 5 kV intervals
0.6-40
Canon DR system
72
70-85, 5 kV intervals
0.6-32
Integral DQE
Because of the amount of data, a single descriptor of image quality was desirable;
the integral detective quantum efficiency (IDQE) reported by Fetterly et al. (2000)
provides a single quantity for photon absorption efficiency, noise and resolution. The
IDQE is integrated over frequency. The DQE defined by Equation 4-6, where k is the
conversion from pixel value to exposure and q is the incident signal-to-noise value to be
described in more detail in the following sections. Traditionally, the IDQE is determined
from Equation 4-7. For each system and configuration in Table 4-1, the IDQE was
determined.
k ⋅ [MTF ( f )]
q ⋅ NPS ( f )
2
DQE ( f ) =
(4-6)
f Nyquist
IDQE =
∫ 2πf ⋅ DQE ( f )df
0
(4-7)
52
Incident Signal-to-Noise, q
The incident signal-to-noise ratio, q was determined with Equations 4-8 and 4-9. In
a simplified case, the noise for a beam of monoenergetic photons N would be √N.
Therefore, the signal to noise ratio would be N/√N or N2/N. This is very similar to the
structure of Equation 4-8. Using Equations 4-8 and 4-9, q (photons/mm) and the air
kerma, X (mGy) were calculated where E is energy (kV), q(E) is the number of photons
for the given energy, (µen/ρ)air is the mass-energy absorption coefficient for air, in units of
cm2/g. The values for q(E) were determined using the TASMIP computer simulation
code (Boone and Siebert, 1997) to estimate the each beam spectra. The input parameters
for TASMIP are peak tube potential energy, inherent filtration and tube ripple. The tube
ripple is 2% and the inherent filtration is 2.2 and 2.7 mmAl equivalent for CR and DR,
respectively values for q, normalized by X are listed in Table 4-2.
(∫ q( E ) EdE )
q=
2
∫ q( E ) E
2
dE
 µ en
X=
(4-8)
∫ q( E ) ⋅ E ⋅ 

ρ  Air dE
(4-9)
 Photons 

6.19 x10 7 
2
⋅
mm
mGy


Table 4-2. Incident signal-to-noise ratio, q for Room 1 (Agfa CR system) and Room 5
(Canon DR system) (photons/mm2*mGy)
kVp
Room 1
Room 5
50
1.26E+07
1.31E+07
55
1.38E+07
1.44E+07
60
1.48E+07
1.55E+07
65
1.57E+07
1.64E+07
70
1.65E+07
1.72E+07
75
1.73E+07
1.80E+07
80
1.80E+07
1.87E+07
85
1.86E+07
1.93E+07
53
4000
Pixel Value
3500
3000
2500
2000
1500
-4
-3
-2
-1
0
Log (Air Kerma [mGy])
Figure 4-3. Pixel value vs. log of air kerma for Canon DR system
4500
Pixel Value
4000
3500
3000
2500
2000
1500
-4.0
-3.0
-2.0
-1.0
0.0
Log (Air Kerma*Speed/200)
Figure 4-4. Pixel value vs. log of air kerma*speed/200 for Agfa CR system
Pixel Value to Exposure Conversion, k
The value k converts the pixel values to exposure values. If the pixel values are
converted to exposure prior to the calculation of the MTF and DQE, the constant k in
Equation 4-6 is not necessary. To determine k, several flat field images for both systems
that were taken at 70 kVp and increasing mAs at a 40 inch SID. Exposure was measured
54
with an MDH ion chamber on the tabletop and converted to air kerma. Since the MDH is
approximately 1.5 inches above the tabletop, the inverse square law was used to
extrapolate the exposure at 40 inched SID. Mean pixel values were determined from a
large area from the center of the flat field images. For Canon DR system, these pixel
values were plotted versus log (air kerma) and the slope of the line is proportional to k as
shown in Figure 4-3. Because the exposure class, or speed, was changed for the Agfa CR
system in the NPS measurement, it must be accounted for in the determination of k.
Using the relationship given by Agfa CR system for exposure level defined in Equation
1-1, speed and air kerma can be combined. The slope of the line given by a plot of pixel
value verses the log (speed/200*air kerma) is proportional to the value of k, as shown in
Figure 4-4.
Results and Discussion
Modulation Transfer Function
Initially, the LSF experiment was tried with a slit camera. There was a problem
with irregularities of the material surrounding the slit. An image of the slit through a
microscope is shown in Figure 4-5. Figure 4-5a shows the material around the slit.
There is visible scratches and corrosion of the slit material. Figure 4-5b shows a
magnified image of light through the slit. It shows that there are inconsistencies of the
edge of the slit. A 3-dimesional rendering of an x-ray image of the slit camera is
illustrated in Figure 4-6. The damage to the material surrounding the slit can be seen in
the 3D model. When taking profiles perpendicular to the slit, it appeared as if there were
55
variations in the width of the slit. These variations in width caused inconsistent MTFs.
Figure 4-5. Image of the slit camera through a microscope. A) Material around the slit.
B) Light through the slit.
To ensure that the MTF was not varying with kVp, an alternate method was
employed. The line pair phantom method gives approximation of the MTF at discrete
frequencies. Figure 4-7 shows the MTF using the line pair phantom for the Agfa CR
system. The plot shows that there is no change in MTF with tube potential. Because a
more continuous MTF was necessary for the calculation of IDQE, the slit camera was
replaced with the Leeds E1 phantom. The 3D image in Figure 4-8 shows that there is no
longer the variation in widths across the line. The MTFs, using the E1 phantom for both
Agfa CR system and Canon DR system, are shown in Figure 4-9. The MTF of Canon
DR system is higher than that of Agfa CR system. That is to be expected since the pixel
size of the 14 inch x 17 inch Agfa CR system plates at standard resolution is 0.17 mm x
0.17 mm and the pixel size of the Canon DR system is 0.16mm x 0.16 mm.
56
Figure 4-6. 3D image of slit camera
1.0
50 kVp
55 kVp
MTF
0.8
0.6
60 kVp
65 kVp
70 kVp
0.4
0.2
0.0
0.0
1.0
2.0
3.0
4.0
5.0
Frequency (cycles/mm)
Figure 4-7. Modulation transfer function of Agfa CR system using line pair function
57
Figure 4-8. 3D image of line on Leeds E1 phantom
1.0
MTF
0.8
0.6
Agfa
Canon
0.4
0.2
0.0
0.0
1.0
2.0
3.0
4.0
Frequency (cycles/mm)
Figure 4-9. Modulation transfer function for Agfa CR system and Canon DR system
using line spread function.
58
Noise Power Spectrum
The NPS versus frequency of the Agfa CR system at 40 inch SID without the grid
is shown in Figure 4-10. The areas under each curve is graphed versus radiographic
technique are shown in Figure 4-11. The graphs for the other configurations are located
in Appendix C. Noise is greatly reduced by increasing mAs. For instance at 70 kVp, for
the Agfa CR system at 40 inch SID without the grid, there is a 23 % reduction in noise by
increasing the mAs from 0.6 to 10.
When comparing systems to each other, Figure 4-12 plots the NPS versus
frequency for all systems and configurations at 70 kVp and 0.6 mAs. For the Agfa CR
system 72 inch configuration with the grid, there is a noticeable spike in the NPS caused
by the stationary grid in the chestboard in Shands Hospital Room 1. The stationary grid
leaves a fixed pattern of grid lines on the flat field images. The table Bucky in Room 1
and the Canon DR system Chestboard have oscillating grids which do not leave a fixed
pattern. With increasing frequency, the NPS for the Agfa CR system decreases while the
Canon DR system remains flat. Figure 4-13 shows the area under the NPS curves for
both systems at all configurations at 70 kVp. This shows that for the Agfa CR system,
the integrated NPS without the grid is less than the NPS with the grid. By using the grid,
there is less exposure to the CR plate.
In both the Agfa CR system and the Canon DR system, the 40 inch SID had a
lower NPS and total noise than the 72 inch SID. Again, there is less exposure to the plate
at the longer SID due to the inverse square law. When comparing the systems to each
other, the Canon DR system has less noise than the Agfa CR system with the grid for the
same technique.
59
50 kVp 0.6 mAs
1.20E-04
50 kVp 1.0 mAs
50 kVp 5.0 mAs
50 kVp 10.0 mAs
50 kVp 20.0 mAs
1.00E-04
50 kVp 32.0 mAs
50 kVp 40.0 mAs
55 kVp 0.6 mAs
55 kVp 1.0 mAs
8.00E-05
55 kVp 5.0 mAs
55 kVp 20.0 mAs
2
NPS (mm )
55 kVp 10.0 mAs
55 kVp 32.0 mAs
6.00E-05
60 kVp 0.6 mAs
60 kVp 1.0 mAs
60 kVp 5.0 mAs
60 kVp 10.0 mAs
4.00E-05
60 kVp 20.0 mAs
65 kVp 0.6 mAs
65 kVp 1.0 mAs
65 kVp 5.0 mAs
2.00E-05
65 kVp 10.0 mAs
65 kVp 20.0 mAs
70 kVp 0.6 mAs
70 kVp 1.0 mAs
0.00E+00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
70 kVp 5.0 mAs
70 kVp 10.0 mAs
Frequency (Cycles/mm)
Figure 4-10. The noise power spectrum for Agfa CR system at 40 inch SID, without the
grid
3.00E-04
2.50E-04
Total System Noise
2.00E-04
1.50E-04
1.00E-04
5.00E-05
50 kVp
55 kVp
0.00E+00
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure 4-11. The total system noise for Agfa CR system at 40 inch SID, without the grid
60
1.00E-04
9.00E-05
8.00E-05
7.00E-05
NPS (mm2)
6.00E-05
5.00E-05
Agfa 40 inches No Grid
Agfa 40 Inches Grid
Canon 40 Inches Grid
Agfa 72 Inches No Grid
Agfa 72 Inches Grid
Canon 72 Inches Grid
4.00E-05
3.00E-05
2.00E-05
1.00E-05
0.00E+00
0
0.5
1
1.5
2
2.5
3
3.5
Frequency (cycles/mm)
Figure 4-12. The NPS of all the systems and configurations at 70 kVp and 0.6 mAs.
3.50E-04
3.00E-04
Agfa 40 No Grid
2.50E-04
Total Noise
Agfa 40 Grid
Canon 40 Grid
2.00E-04
Agfa 72 No Grid
Agfa 72 Grid
1.50E-04
Canon 72 Grid
1.00E-04
5.00E-05
0.00E+00
0.6
1
5
10
mAs
Figure 4-13. The total system noise for all systems and configurations at 70 kVp.
61
Integral DQE
The IDQE is the single unit descriptor of image quality. Figure 4-14 graphs the
IDQE versus kVp and mAs for the Agfa CR system using a 40 inch SID without a grid.
The graphs for the other configurations are located in Appendix D. For a given kVp, the
image quality generally improves with increasing mAs. One would expect image quality
to improve with increasing mAs because more photons mean less noise. But, these
graphs also show that there is a point were the IDQE levels off, i.e., there is no additional
image quality improvement by increasing the mAs or exposure. For a given mAs, the
IDQE increases with a reduction in kVp. Because IDQE increases with quantum
efficiency and efficiency decreases with higher energies, the IDQE behavior shown is
expected.
Figure 4-15 compares the systems and configurations to each other at 70 kVp.
Other kVp comparison graphs are found in Appendix D. For Agfa CR system, the
configuration without the grid gives a higher DQE than with the grid for both 40 and 72
inch SID. By using table top techniques, more photons are able to reach the plate,
improving the image quality. For both the Agfa CR system and the Canon DR systems,
the shorter SID gives a higher IDQE for all mAs values. At the shorter SID, more
photons reach the plate. To compare the Agfa CR system to the Canon DR system, the
Agfa CR system was measured with a grid and the Canon DR system had a higher IDQE
than Agfa CR system. The Canon DR system has a smaller pixel size resulting in a
higher Nyquist frequency than the Agfa CR system 14 inch x 17 inch cassettes at
standard resolution. Also the scintillator screen used in the Canon DR system has a
greater quantum efficiency than the BaSrFBrI:Eu plates used in the Agfa CR system.
62
6.00
5.00
IDQE (1/mm)2
4.00
3.00
2.00
1.00
50 kVp
55 kVp
0.00
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure 4-14. IDQE for various techniques for Agfa CR system at 40 inch SID without the
grid.
6.00
5.00
4.00
IDQE (1/mm)
2
A40NG
A40G
C40G
A72NG
A72G
C72G
3.00
2.00
1.00
0.00
0.6 mAs
1 mAs
5 mAs
10 mAs
Figure 4-15. IDQE for both systems at all configurations at 70 kVp.
These IDQE measurements were plotted versus technique and not exposure.
Comparing image quality versus technique is fine within a system. But it becomes a
63
problem when comparing different systems that do not use the same tube. Although the
tubes and generator are identical in make and model, there are differences in inherent
filtration between the tubes. Even with the same techniques being used, namely kVp and
mAs, this does not guarantee that the exposures are the same. Further investigation in the
chapter will truly compare the two systems.
Summary
The IDQE can be used as a single unit descriptor of image quality. This unit allows
for comparison of image quality at differing techniques as well as different systems.
Using clinically relevant radiographic techniques, image quality can be measured how it
is used in clinical practice.
The MTF of the Canon DR system was higher than that of the Agfa CR system due
to the smaller pixel value of the Canon. The noise of the Canon DR system was lower
than that of the Agfa CR system. The IDQE of the Canon DR system was higher than the
Agfa CR system for the same technique. In the next section, the comparison of the two
systems is made with air kerma to the image receptor, entrance skin exposure and
effective dose instead of radiographic technique.
CHAPTER 5
DEVELOPMENT OF RADIOGRAPHIC TECHNIQUES
Introduction
New imaging modalities such as digital radiography (DR) and computed
radiography (CR) offer the possibility of better image quality than conventional
screen/film at reduced doses. Without an appropriate method of predicting useful
radiographic techniques, most facilities still use techniques originally developed for
screen/film system. With the concern for dose, especially for pediatric patients, it is
important to investigate the potential of these new imaging modalities. Since the sizes of
children vary, it is important to determine a relationship between effective dose, tube
potential and current and IDQE for CR and DR for pediatric patients. Using pediatric
anthropomorphic phantoms and evaluating objective measures of image quality, the
radiographic techniques for pediatric patients can be optimized for CR and DR.
Materials and Methods
Pediatric Anthropomorphic Phantoms
Anthropomorphic phantoms have been designed to simulate the attenuation and
scatter characteristics in the body. Two phantoms were constructed at the University of
Florida to simulate newborn and one-year-old patients. The height and weight of these
phantoms can be found in Table 5-1. The anthropomorphic phantoms consist of a
skeleton, lungs and soft tissue. The goal of this phantom was to create a physical model
of the Cristy and Eckerman pediatric model shown in Figure 5-1.
64
65
Figure 5-1. Mathematical phantom models. (Cristy 1980)
The phantom materials are required to match both the density and attenuation of
real tissues in the body. The densities of the soft tissue, lung and bone material for the
newborn and one-year-old phantoms are listed in Table 5-1. The phantoms are made of
three different regions, trunk, legs and head as seen in Figure 5-2 (A). The trunk region
is cylindrical and composed of a soft-tissue equivalent material which encloses the lungs
and skeleton, displayed in the radiograph shown in Figure 5-2 (D). The skeleton in the
trunk consists of arm bones, pelvis, spine, ribs, scapula and clavicles seen in Figure 5-2
(B). The arms were placed by the phantoms side and encased in the trunk illustrated in
Figure 5-2 (C). The leg region is the frusta of two soft tissue cones surrounding leg
bones. The head region is modeled after the Bouchet-Bolch head model described in
“Revised dosimetric models of the pediatric head and brain” (Bouchet et al. 1997), which
consists of a head, containing the mandible, teeth, cranium and upper facial region as
well as a neck so that the thyroid dose can be measured. Guides (small holes) were drilled
in the phantom allow for placement of the dosimeters. The dosimeters were placed in the
bone and at the centroid of the soft organs for measurement.
66
Table 5-1. Information on newborn and one-year-old UF phantoms
Newborn
One-Year-Old
Height
50 cm
75 cm
Weight
4 kg
10 kg
3
Lung density
1.04 g/cm 1.04 g/cm3
Bone density
1.22 g/cm3 1.18 g/cm3
Soft tissue Density
0.30 g/cm3 0.36 g/cm3
(A)
(B)
Figure 5-2. UF Anthropomorphic Phantom.
(C)
(D)
Certain approximations are made in using these phantoms. These phantoms
represent both male and female patients where measurements are made for both types of
gonads. The breast dose was measured midway between the breasts since the breasts of
newborn and one-year-old children are so small. A single measurement was made for the
testes since they are very close together. The dosimeter locations in skeleton were chosen
with three criteria in mind. First, the bone had to large enough to accept the MOSFET
without loss of a significant percentage of the bone material. Secondly, the bones
selected represent a high concentration in active bone marrow. Lastly, the locations had
to cover a large percentage of the skeleton. (Bower, 1997).
67
MOSFET Dosimeters
A commercial Patient Dose Verification system manufactured by Thomson &
Nielsen Electronics Ltd9., shown in Figure 5-3, was used in this research. The basic
system consists of a reader, a bias supplies, power supply, and MOSFET dosimeters.
Each dosimeter consists of two MOSFET devices mounted together operated at different
bias voltage. Each MOSFET device has an active area of 0.04 mm2 and the pair are
mounted under a 1 mm thick layer of black epoxy to a 20 cm long thin semi-opaque
polyamide laminate cable encasing two gold wires. The extremely thin and flexible
laminate cable is attached to a sturdy 1.4 m cable which is connected to the dual bias
supply. The patient verification dosimeter system can accommodate up to 20 dosimeters.
To facilitate monitoring of the lower absorbed doses associated with diagnostic x-ray
systems; the model TN-RD-19 high-sensitivity bias supply is used.
Figure 5-3. MOSFET dosimetry system
9
Thomson & Nielsen Electronics Ltd ., 25E Northside Road, Nepean, Ontario, Canada, K2H 8S1
68
Dose Measurements
MOSFET dosimeters were placed in the guide holes of the pediatric
anthropomorphic phantoms. The phantoms were placed on the table or at the chestboard
as seen in Figure 5-4 and exposed for all the configurations listed in Table 4-1. The light
field was centered on the torso of the phantom and the light field was opened to cover the
entire torso. The MDH ion chamber was placed in the field along side the phantom to
measure the exposure. MOSFET read out in mV and can be converted to organ-absorbed
dose with Equation 5-1. The conversion factor (CF) converts the mV reading to air
kerma [mGy]. The conversion factor is determined by exposing the MOSFETs to a
known exposure and dividing the mV reading by that exposure. The bone marrow dose
was determined using the MOSFET readings for the bone locations with soft tissue massenergy absorption coefficients. Using Equation 1-6, the organ absorbed doses can be
converted to effective dose. The doses were normalized by the air kerma.
DTissue
 µen 

ρ Tissue 1

= 0.876 ⋅
⋅
⋅ mV
CF
 µen 

ρ  Si

Figure 5-4. Anthropomorphic phantom placed on the table or at the chestboard
(5-1)
69
Image Quality Measurements
The method for determining IDQE was detailed in the previous chapter. The image
quality was determined for the Agfa ADC system and Canon CXDI-11 system in the
configurations listed in Table 4-1. In order to fairly compare the systems, the IDQE was
plotted versus air kerma at the image receptor for each configuration listed in Table 4-1.
In order to measure the air kerma at the image receptors, measurements were taken inside
the Bucky using a thin exposure meter called the Barracuda manufactured by RTI
Electronics Inc.10 for Agfa CR system configurations with the grid. The Barracuda
matched very well with the MDH and the exposure measurements were converted to air
kerma. Measurements for Agfa CR system without the grid and Canon DR system
configurations were measured using the MDH ion chamber placed on the tabletop. The
center of the MDH stands approximately 3.0 cm from the tabletop. Using the inverse
square law, the exposure measurements were extrapolated to the tabletop and converted
to air kerma. Since the Canon DR system used the same type of grid as the Agfa CR
system, a Bucky factor was determined from the Agfa CR system data. The Bucky factor
is the ratio of the transmitted radiation to the incident radiation. Using exposure
measurements from the MDH at the tabletop as the incident radiation and the Barracuda
in the Bucky as the transmitted radiation, a Bucky factor was determined. This Bucky
factor was applied to the Canon DR system exposure measurements at the tabletop to
determine the exposure to the image receptor behind the gird. Exposure measurements
were converted to air kerma by multiplying the mR measurements by 0.087 mGy.
10
RTI Electronics, Göteborgsv 97 / 50, SE-431 37 MÖLNDAL, Sweden
70
The IDQE was then plotted versus log of air kerma and coefficients for equations
in the form of Equation 5-2 are calculated from fitting a line through the data.
Coefficients a and b are contained in Appendix E.
IDQE = a log (air kerma [mGy]) + b
(5-2)
Entrance skin exposure (ESE) for each of the phantoms was determined by taking
the exposure measurements on the tabletop with the MDH ion chamber. Those
measurements were extrapolated to the entrance of the phantom using the inverse square
law. The entrance skin exposures were converted to air kerma. For each configuration
and phantom, the IDQE was plotted versus entrance skin exposure and coefficients for
equations in the form of Equation 5-2 are calculated from fitting a line through the data.
Coefficients a and b are contained in Appendix E. Similarly, the IDQE was plotted vs.
effective dose for both phantoms. Coefficients for equations in the form of Equation 5-2
are calculated from fitting a line through the data. Coefficients a and b contained in
Appendix E.
Radiographic Technique Determination
The relationship between IDQE and ESE was used to develop a radiographic
technique chart for pediatric chest imaging. The automatic exposure control (AEC) was
used to make an initial estimate of the radiographic techniques necessary for pediatric
chest imaging. The phantoms were placed on either the table or in front of the chestboard
as seen in Figure 5-4 for both the Canon DR system and the Agfa CR system. The AEC
system is contained in the Bucky with the grid for the Agfa CR system and as a part of
the chestboard for the Canon DR system. Only the center AEC sensor was selected
because the phantoms do not cover all three AEC sensors. An MDH ion chamber was
placed in the field to record the exposure for each phantom image. The exposures were
71
converted to ESE for both the newborn and one-year-old phantoms. Using the tube
outputs (mGy/mAs) in Table 5-2, the mAs was converted to air kerma in mGy.
Table 5-2. Tube outputs (mGy/mAs) for Room 1 (Agfa CR system) and Room 5 (Canon
DR system)
kVp
Room 1
Room 5
40 inches 72 inches 40 inches 72 inches
50
1.68E-02
1.14E-02
55
2.08E-02
1.59E-02
60
2.55E-02
2.01E-02
65
3.19E-02
2.51E-02
70
3.82E-02
9.82E-03
2.95E-02
8.39E-03
75
1.18E-02
9.82E-03
80
1.39E-02
1.16E-02
85
1.57E-02
1.34E-02
To ascertain the image quality of the AEC images, the air kerma corresponding to
the AEC examinations were converted to IDQE for each kVp using Equation 5-2. Those
air kerma values were reduced by 25%, 50% and 75% and placed back into Equation 5-2
with the appropriate coefficients to determine the IDQE for the reduced AEC settings.
These reduced air kerma values were converted to mAs using the tube outputs in Table 52 values for each kVp. A radiographic technique chart was developed from the mAs
values corresponding to the 75% reduced AEC settings for each kVp.
For the Agfa CR system, there are two configurations without the grids. To
maintain the image quality of the image used with the grid, the 75% reduced IDQE
values were place in Equation 5-1 using the non-grid coefficients. Those equations were
solved for air kerma and the air kerma values were converted to mAs using the tube
outputs. These kVp and mAs values were placed in the radiographic technique chart.
72
Results and Discussion
Relationship between IDQE and Air Kerma at the Image Receptor
The relationship between IDQE and air kerma at the image receptor was
established by the graphs such as Figure 5-5. The graphs for the remaining
configurations are contained in Appendix D. Figure 5-5 shows that the IDQE is higher
for lower tube potentials. It also shows that above air kerma values of 0.1 mGy, there is
little improvement in the IDQE.
The previous chapter stated that a fairer comparison between systems could be
achieved if IDQE was plotted versus air kerma at the image receptor. Figure 5-6 shows
IDQE for both the Canon DR system and Agfa CR system at all the configurations at 70
kVp. By using the air kerma at the image receptor, it shows that there is no difference in
IDQE with SID for the Canon DR system. The same is true for the Agfa CR system;
there is no difference in IDQE with SID and grid use. The Canon DR system has a
higher IDQE than the Agfa CR system. This would be expected because of the smaller
pixel size of Canon DR system. Also, the conversion from incident photons to diagnostic
image is more efficient for the Canon DR system. For the Canon DR system, the photons
are converted into light using the scintillator and the TFTs convert the light to electronic
signal which becomes the image. The Agfa CR system has more processing steps. Once
the image receptor is exposed, the cassette is placed in the reader. The light is released
with a laser and the light is collected by the PM tubes. The analog-to-digital converter
converts the signal to an image.
73
5.00
4.50
IDQE (1/mm)
2
4.00
3.50
50 kVp
3.00
55 kVp
60 kVp
65 kVp
70 kVp
2.50
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Air Kerma (mGy)
Figure 5-5. IDQE vs. air kerma at the image receptor for Agfa CR system at 40 inch SID
with the grid
6.50
Agfa 40 No Grid
6.00
Afa 72 No Grid
5.50
Agfa 40 Grid
Agfa 72 Grid
IDQE (1/mm)2
5.00
Canon 40 Grid
Canon 72 Grid
4.50
4.00
3.50
3.00
2.50
2.00
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
Air Kerma [mGy]
Figure 5-6. IDQE vs. air kerma at the image receptor for all configurations at 70 kVp
74
Figure 5-7 shows the IDQE versus the log of air kerma. These straight lines are
approximated with a linear fit which is ideal for relating image quality with air kerma.
This relationship allows the prediction of image quality from air kerma measurements.
Also, by using the tube output (air kerma/mAs), a relationship between IDQE and mAs
used for the image can also be established as shown in Equation 5-3. Figure 5-8 shows
the relationship between IDQE and mAs at 70 kVp for both systems and all
configurations. The abbreviations used in the chart are:
1.
A40NG – The Agfa CR system without the use of the grid at a 40 inch SID.
2.
A40G – The Agfa CR system with the use of the grid at a 40 inch SID.
3.
A72NG – The Agfa CR system without the use of the grid at a 72 inch SID.
4.
A72G – The Agfa CR system with the use of the grid at a 72 inch SID.
5.
C40G – The Canon DR system with the use of the grid at a 40 inch SID.
6.
C72G – The Canon DR system with the use of the grid at a 72 inch SID.
At lower mAs settings, the Agfa DR system at a 40 inch SID without the grid
provides a better image quality than the Canon DR system, as measured by the IDQE.
IDQE = a * log [tube output * mAs] + b
(5-3)
Relationship between IDQE and Entrance Skin Exposure
Similar to the relationship between IDQE and air kerma at the image receptor, a
relationship between IDQE and ESE was also developed. Graphs of IDQE versus ESE
for newborn and one-year-old patients for both systems and all configurations can be
found in Appendix D. The slope of the resultant equations in the form of Equation 5-2
were the same as with air kerma at the image receptor but the intercept was different.
The intercepts are found in Appendix E. Because ESE changes with patient size, there
are intercepts for both newborn and one-year-old patients. The equations can be used to
75
compare the two systems, as well as different configurations of the same system. Table 53 shows the resultant IDQE after setting the ESE to 0.01 mGy for newborn patients. This
shows that for the same ESE to the patient the Canon DR system provides better image
quality as measured by the IDQE. Similarly, Table 5-4 shows the resultant ESE after
setting the IDQE to 4 for newborn patients. Entrance skin exposure is lower for the
Canon DR system.
Table 5-3. The IDQE for the same entrance skin exposure (0.01 mGy) for newborn
patients.
A40NG A40G C40G
A72NG A72G
C72G
50 kVp
3.58
2.98
4.26
55 kVp
3.31
2.73
3.94
60 kVp
3.06
2.55
3.67
65 kVp
3.01
2.42
3.53
70 kVp
2.87
2.37
3.41
2.82
2.50
3.76
75 kVp
2.71
2.41
3.58
80 kVp
2.62
2.33
3.49
85 kVp
2.56
2.27
3.39
Table 5-4. The entrance skin exposure (mGy) for newborn patients for the same IDQE
value of 4.
A40NG
A40G
C40G
A72NG
A72G
C72G
50 kVp 2.68E-02 1.13E-01 7.39E-03
55 kVp 5.86E-02 2.63E-01 1.08E-02
60 kVp 1.35E-01 5.12E-01 1.53E-02
65 kVp 3.10E-01 9.92E-01 1.98E-02
70 kVp 5.40E-01 2.18E+00 2.44E-02 3.62E-01 4.29E+00 1.44E-02
75 kVp
6.02E-01 1.09E+01 1.88E-02
80 kVp
1.14E+00 1.94E+01 2.27E-02
85 kVp
2.50E+00 5.57E+01 2.71E-02
76
5.00
4.50
IDQE (1/mm)2
4.00
3.50
50 kVp
55 kVp
3.00
60 kVp
65 kVp
70 kVp
2.50
0.00
0.01
0.10
1.00
Log (Air Kerma) [mGy]
Figure 5-7. IDQE vs. log (air kerma) at the image receptor for Agfa CR system at 40 inch
SID with the grid
5.50
5.00
IDQE (1/mm)2
4.50
4.00
3.50
A40NG
3.00
A40G
C40G
2.50
A72NG
A72G
C72G
2.00
0.0
5.0
10.0
15.0
mAs
Figure 5-8. IDQE vs. mAs used in newborn imaging at 70 kVp.
20.0
77
Pediatric Radiographic Techniques
Figure 5-9 shows the IDQE for the AEC and those reduced by 25%, 50% and 75%
used in the development in radiographic technique charts for the Agfa CR system at a 40
inch SID using the grid. Similar graphs are found in Appendix D for the remaining
configurations. There is only a 10% - 15% difference in IDQE by reducing the AEC
exposures by 75%. The radiographic techniques developed for newborn and one-yearold patients are listed in Tables 5-5 and 5-6, respectively. The tables contain mAs values
that correspond to the AEC values reduced by 75%. The radiographic techniques
developed here for the Agfa CR system match very well with the mAs settings that a
technologist would select for pediatric patients the same size and weight as the pediatric
phantoms, especially for 70 kVp, 40 inch SID and no grid used. Since the Canon DR
system is not used on the patients under 4 years of age at Shands at the University of
Florida, this has proven helpful in developing appropriate radiographic techniques for
these patients.
Figure 5-10 shows images of the newborn phantom created with the Agfa CR
system. The first image was obtained using AEC at 70 kVp and 250 mA with a 40 inch
SID. The second image uses the technique found in Table 5-5 for 70 kVp at 40 inches
with the grid. The first image is much darker and detail in the lung is not as visible.
Although the image quality is better for lower tube potentials, the times associated
with the mAs settings would be too long for practical use. In order to minimize motion
effects, a lower mAs is needed. The grid may be necessary to reduce scatter in adult
patients, but newborn and one-year-old patients are thin and do not produce nearly as
much scatter as adult patients. The same argument can be used for a shorter SID. A
78
longer SID also allows for scatter reduction, but in the smaller patients, there is not as
much scatter so a short SID can be used.
5.00
4.50
IDQE (1/mm)2
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
AEC
3.00
0.75*AEC
0.50*AEC
0.25*AEC
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Entrance Skin Expousre (mGy)
Figure 5-9. Reduced AEC values vs. ESE for newborn For the Agfa CR system at a 40
inch SID using the grid
AEC helps to eliminate some of the guess work in selecting radiographic
techniques since it will automatically terminate the exposure when the optimal exposure
level is reached. But small children are too small to cover all the AEC chambers and
therefore, AEC is not necessarily appropriate for children. Manual techniques are best
for pediatric patients. The radiographic technique charts developed here are based on the
response of the AEC system, which makes the Canon DR system require a higher mAs
than the Agfa CR system for newborn and one-year-old patients. This is a result of how
the Canon DR AEC system is configured because Table 5-3 shows that for the same ESE
the Canon DR system should provide a better image quality than the Agfa CR system as
79
measured by the IDQE. With the Canon DR system having a higher IDQE than the Agfa
CR system at the same exposures, and the same anthropomorphic phantoms being used
on both system, the Canon DR system should have given lower AEC settings. Although
the Canon DR system provides superior image quality at lower ESE, the mechanism
available for predicting the response of the system provided by Canon is not fully
understood at Shands Hospital at the University of Florida. There is a well defined
equation (Equation 1-1) for the Agfa CR system which provides a reliable method to
determine the exposure level.
(A)
(B)
Figure 5-10. Image of newborn patient using Agfa CR system at 70 kVp at 40 inch SID
with grid, A) uses the AEC system and B) uses manual techniques.
Table 5-5. Newborn radiographic technique chart
A40NG A40G
C40G A72NG
50 kVp
1.3
3.6
17.9
55 kVp
1.1
3.3
10.5
60 kVp
1.2
3.0
6.0
65 kVp
0.8
2.0
3.8
70 kVp
0.5
1.5
2.6
1.6
75 kVp
1.4
80 kVp
1.5
85 kVp
1.1
A72G
C72G
5.5
5.5
5.4
4.6
19.8
8.5
6.0
4.6
80
Table 5-6. One-Year-Old radiographic technique chart
mAs
A40NG A40G
C40G
A72NG A72G
50 kVp
2.9
8.3
31.3
55 kVp
2.6
7.4
20.8
60 kVp
2.5
6.5
11.5
65 kVp
1.7
4.1
7.1
70 kVp
1.1
2.8
4.7
2.7
10.6
75 kVp
2.3
10.3
80 kVp
2.6
10.1
85 kVp
1.9
8.5
C72G
19.0
13.1
9.1
6.9
Effective Doses
Effective doses measured at techniques shown in Tables 5-5 and 5-6 with the
newborn and one-year-old anthropomorphic phantoms are presented in Tables 5-7 and 58. The details of effective dose calculations are contained in Appendix F. Although,
there is an increase in mAs by increasing the SID from 40 inches to 72 inches for the
Agfa CR system at 70 kVp, there is a reduction of dose. The opposite is true for the
Canon DR system; the effective dose increases with increasing SID. For the Agfa CR
system, there is a great reduction in dose by not using the grid, ~70%. Although the
Canon DR system has better image quality than the Agfa CR system overall, the effective
dose for patients is higher with the Canon DR system than with the Agfa CR system. The
mAs values were considerably higher than the Agfa CR system values, which could lead
to higher effective doses. Again, since these mAs values are based on the initial estimate
provided by the AEC system, the Canon DR system will have a higher mAs settings and
higher effective doses. Taking dose, kVp and mAs into consideration, the best technique
for the Agfa CR system is 70 kVp, 0.5 mAs, 40 inch SID without the grid. For the Canon
DR system, 70 kVp, 2.6 mAs with a 40 inch SID.
81
Table 5-7. Effective doses (mSv) for newborn patients using techniques in Table 5-3
A40NG
A40G
C40G
A72NG
A72G
C72G
50 kVp
6.03E-03 2.04E-02 5.82E-02
55 kVp
6.01E-03 2.10E-02 4.21E-02
60 kVp
1.08E-02 3.30E-02 4.28E-02
65 kVp
8.96E-03 2.80E-02 3.47E-02
70 kVp
7.82E-03 2.41E-02 2.90E-02 4.49E-03
1.65E-02
4.82E-02
75 kVp
4.98E-03
2.04E-02
2.49E-02
80 kVp
7.10E-03
2.62E-02
2.32E-02
85 kVp
7.37E-03
3.13E-02
2.54E-02
Table 5-8. Effective doses (mSv) for one-year-old using techniques in Table 5-4
mAs
A40NG
A40G
C40G
A72NG
A72G
C72G
50 kVp 1.45E-02 4.91E-02 1.05E-01
55 kVp 3.31E-02 1.13E-01 2.03E-01
60 kVp 7.95E-02 2.41E-01 2.83E-01
65 kVp 7.71E-02 2.17E-01 2.52E-01
70 kVp 9.21E-02 2.78E-01 3.11E-01
5.97E-02 2.50E-01 3.59E-01
75 kVp
8.66E-02 4.12E-01 4.14E-01
80 kVp
1.06E-01 4.37E-01 3.13E-01
85 kVp
1.28E-01 6.07E-01 4.02E-01
The IDQE can be used as a dose indicator. Systems with a higher IDQE have the
ability to produce a better image quality at lower doses. Using the equations relating
IDQE with effective dose, Table 5-9 shows the IDQE for the same effective dose of 0.01
mSv. Like previous tables, it shows that the Canon DR system has a better image quality
than the Agfa CR system, as measured by the IDQE. Similarly, Table 5-10 shows the
effective dose for the same IDQE value of 4. The Canon DR system has the ability to
produce the same image quality at a lower effective dose than the Agfa CR system.
Summary
The image quality measurements taken in the previous chapter were plotted versus
air kerma at the image receptor, ESE and effective dose. With these plots, relationships
between image quality and radiation quantities were established. The relationship
between IDQE and ESE allowed the development of radiographic technique charts for
82
pediatric patients, especially for the Canon DR system which has not been previously
used for small children. The radiographic techniques at the lower tube potentials had
large mAs settings which would correspond to a longer exposure times. The longer
exposure times lead to motion artifacts in images. To help optimize radiographic
technique, the effective dose measurements gave additional information about each
radiographic technique. After balancing all the parameters for the best image quality at
the lowest dose, radiographic technique charts were developed for both the Agfa CR
system and the Canon DR system for use with pediatric patients.
Table 5-9. IDQE for the same effective dose (0.01 mSv) for newborn patients
A40NG
A40G
C40G
A72NG
A72G
C72G
50 kVp
4.22
3.63
5.59
55 kVp
3.94
3.37
5.24
60 kVp
3.52
3.03
4.67
65 kVp
3.39
2.86
4.40
70 kVp
3.23
2.75
4.23
3.27
2.84
4.68
75 kVp
3.13
2.72
4.47
80 kVp
2.98
2.60
4.26
85 kVp
2.82
2.47
4.01
Table 5-10. Effective dose for the same IDQE value of 4 for newborn patients.
A40NG
A40G
C40G
A72NG
A72G
C72G
50 kVp
5.97E-03 2.43E-02 1.62E-03
55 kVp
1.16E-02 5.05E-02 2.11E-03
60 kVp
3.78E-02 1.39E-01 4.20E-03
65 kVp
8.33E-02 2.73E-01 5.55E-03
70 kVp
1.49E-01 6.17E-01 7.02E-03 9.20E-02 1.09E+00 3.65E-03
75 kVp
1.58E-01 2.84E+00 4.92E-03
80 kVp
3.32E-01 5.65E+00 6.61E-03
85 kVp
9.05E-01 2.01E+01 9.78E-03
CHAPTER 6
CONCLUSION
The Agfa CR system uses reusable photostimulatable phosphor plates made of
BaSRFBrI:Eu material. The Canon DR system uses an amorphous silicon TFT array
with a Gd2O2S:Tb scintillator screen. Both of the digital systems tie into the PACS
where the images are displayed and stored. It is important to measure the image quality
of these digital systems to take advantage of potential for dose reduction. Evaluating the
image quality in an objective manner allows for the comparison of these systems. The
objective measures of image quality measured in this study were MTF, NPS and IDQE.
The MTF is a measure of the spatial system resolution, NPS is a measure of noise and
IDQE is a single unit descriptor of the overall system image quality.
Normally, objective image quality measurements are taken at standard distances
and tube potentials. In this research, the objective image quality measurements were
taken at clinically relevant parameters in order to accurately observe what the image
quality would be in clinical practice. In the past, these measurements are only used to
evaluate system’s performance, and compare systems to each other. These image quality
measurements were taken further by establishing a relationship between image quality
and different radiological parameters such as entrance skin exposure. This relationship is
very useful because it shows how image quality of a digital imaging system changes with
input exposure. In this research, the relationship between image quality and the
radiological quantities was coupled to the tube output to develop radiographic technique
charts for pediatric chest imaging. Effective doses measured with anthropomorphic
83
84
pediatric phantoms provided additional information and aided in the optimization of
radiographic techniques for pediatric patients. The effective doses for the Canon DR
system is were higher than the Agfa CR system for the radiographic techniques predicted
in this research. At Shands at the University of Florida, the Agfa CR system is used for
imaging the smallest patients (less than 4 years of age). The radiographic techniques
developed in this research for the Agfa CR system were identical to the radiographic
techniques that a technologist would select for a patient the same size and weight of the
pediatric phantoms. The technologist uses experience, as well as a little trial and error, to
determine the proper radiographic techniques to produce the best image. The method
developed in this research was able to predict the same radiographic techniques for the
Agfa CR system as a technologist without the trial and error. The method for predicting
appropriate radiographic techniques is also useful for setting up new systems such as the
Canon DR system at Shands at the University of Florida which is currently not used on
patients under 4 years of age.
The first five hypotheses were proven true. Hypothesis 1 states that “an increase in
peak tube potential (kVp) will not change the MTF of the CR or DR systems.”
Determining the MTF using the line pair phantom proved that the MTF does not change
with tube potential. Hypothesis 2 states, “the increase of tube current and time (mAs)
will produce lower NPS” and Hypothesis 4 states “the use of a longer SID will produce
higher NPS.” For both the Agfa CR system and the Canon DR system, the NPS
decreased with higher mAs, and shorter SID. Hypothesis 3 states that “the use of the grid
during image production will produce higher NPS than images taken without the grid.”
For the Agfa CR system, there was a decrease in NPS with the removal of the grid. The
85
NPS decreased for those cases because more photons were able to reach the imaging
plates. Hypothesis 5 states “IDQE will increase for lower tube potentials.” IDQE
decreased with higher kVp for both systems. The final hypothesis, “DR will provide
better image quality than CR with reduced doses for pediatric patients,” was also proven
true. The Canon DR system did have superior image quality to the Agfa CR system for
lower effective dose.
This research has proven that it is possible to measure image quality objectively at
clinically relevant parameters for digital systems. This was the first time a mathematical
relationship between image quality and radiation quantities had been established. This
information is not only useful in comparing systems but it also helps to produce optimal
radiographic techniques for pediatric patients.
Future Work. In the future, the MTF and NPS measurements should be repeated
for the Canon DR system without the grid to compare to the Agfa CR system without the
grid. It was not feasible in this research to remove the grid from the Canon DR system
since it was in constant clinical use. Image quality measurements should be repeated
using the same x-ray tube for both the CR and DR systems. This will help to eliminate
some of the differences in x-ray tube output and discrepancies in the image quality
measurements between the CR and DR systems. To expedite the prediction of
radiographic techniques, one user-friendly software program could be developed that
would incorporate all the image quality measurements. The inputs to the software
program would be flat field and line images to determine the NPS and MTF, respectively.
The output would be NPS, MTF and IDQE calculations. If x-ray tube information is
86
included in the software program, it could generate an exposure chart for the digital
imaging system.
APPENDIX A
EXAMPLE OF MTF CALCULATION USING LINE PAIR PHANTOM
The following is a calculation of the MTF for the Agfa CR system at 50 kVp, 10
mAs and 40 inch SID using the Hüttner line pair phantom. The standard deviation and
mean values were determined using Medisurf software. Figure A-1 identifies the
different regions of the Hüttner line pair phantom. The values for the mean and standard
deviation for the light and dark regions are shown in Table A-1. Equation A-1 shows the
calculation of the noise, N and Equation A-2 shows of Mo. The M’ values found in
Equation A-3 and Table A-2 are the standard deviation of the line pair regions of
frequency, f. Equation A-4 is the calculation of the MTF at frequencies, f and the values
are displayed in Table A-2. The “Norm” values in Table A-2 are the MTF(f) values
divided by MTF(0.5).
Dark Region
Line Pair Regions of
varying frequencies, f
Light Region
Figure A-1. Anatomy of Hüttner line pair phantom.
Table A-1. Standard deviation and mean of light and dark regions of the Hüttner Phantom
Standard
Deviation
Mean
Light
29.467
923.181
Dark
14.247
1671.52
87
88
N Light = Standard deviation of light region = 29.467
N Dark = Standard deviation of dark region = 14.247
N
2
(N
=
M Light
2
Light
2
+ N Dark
) = (29 .467
)
+ 14 . 247 2
= 535.6405
2
2
= M ean of light region = 923.181
2
(B-1)
M Dark = M ean of dark region = 1671.52
Mo =
M =
M Light − M Dark
(M ′
MTF ( f ) =
2
2
−N
2
=
923 . 181 − 1671 . 52
)
2
= 374.1695
(B-3)
π 2 M(f)
(B-4)
⋅
M0
4
Table A-2. Calculation of the MTF
f (lp/mm)
M'
M
0.5
255.314 254.2629
0.56
252.986 251.9251
0.63
238.418 237.292
0.71
221.069 219.8542
0.8
210.237 208.9592
0.9
193.334 191.9437
1.0
174.56 173.0189
1.12
165.715 164.0909
1.25
146.622 144.7839
1.4
129.374 127.287
1.6
111.63 109.2045
1.8
94.775 91.90571
2.0
76.925 73.36086
2.25
69.039 65.04416
2.4
51.786 46.32655
2.8
44.168 37.61877
3.15
38.438 30.6894
3.55
33.68 24.46838
4.0
18.516
0
4.5
15.872
0
5.0
19.547
0
(B-2)
MTF (f)
0.754778
0.747839
0.7044
0.652636
0.620295
0.569784
0.513606
0.487103
0.42979
0.377851
0.324173
0.272822
0.217771
0.193083
0.13752
0.111671
0.091101
0.072634
0
0
0
Norm.
1.000
0.991
0.933
0.865
0.822
0.755
0.680
0.645
0.569
0.501
0.429
0.361
0.289
0.256
0.182
0.148
0.121
0.096
0.000
0.000
0.000
APPENDIX B
MATLAB CODES
Modulation Transfer Function
The following is the Matlab code for the calculation of the modulation transfer function.
% Clearing memory and screen values
clear;clc;
% Reading the image
Q=imread('line.tif','tif');
% Converting it to double precision
Q=double(Q);
% Determining the size of the image
[M,N]=size(Q);
% Determining the line spread function (LSF) from the image, finding the peak of the
LSF and adjusting the LSF to account for the angle.
B=zeros(1,64);
for i=1:2:N
A=Q(i,:);
A=A-min(A);
A=A/max(A);
[Y,I]=max(A);
A=A(I-32:I+31);
B=B+A;
end
B=B-min(B);
B=B/max(B);
figure(3);plot(B);
B=B-.1;
for i=1:64
if B(i)<0
B(i)=0;
end
end
ZZ45=B;
89
90
% Terminating the long tails on the LSF
[M,N]=size(ZZ45);
for i=1:N
if ZZ45(i)<0.1*max(ZZ45)
ZZ45(i)=0;
end
end
G=zeros(1,100);
ZZ45=cat(2,G,ZZ45,G);
ZZ45=ZZ45/max(ZZ45);
[Y,I]=max(ZZ45);
ZZ45=ZZ45(1,I-64:I+64);
% writing the line spread function to a text file
dlmwrite('lsfslit.txt',ZZ45,'\r');
% plotting the line spread function
figure(1); subplot(1,2,1);plot(ZZ45,'rd-')
title('Line Spread Function using Slit at small degree angle')
% Calculating the MTF values
ZZMTF45=abs(real(fft(ZZ45)));
% Normalizing the MTF values to the zero frequency MTF value
ZMTF45=ZZMTF45/ZZMTF45(1);
%Plotting the normalized MTF values
figure(1); subplot(1,2,2);plot(ZMTF45(1:64),'rd-')
title('Line Spread Function using Slit at small degree angle')
%writing the MTF values to a text file
dlmwrite('slit.txt',ZMTF45(1:64),'\r');
Noise Power Spectrum
The following is the Matlab code for noise power spectrum.
%Clearing the memory and screen values
clc;clear;
% Reading in dicom flat field image
info = dicominfo('I0001_1');
A = dicomread(info);
%figure(1);imagesc(A);
91
%Splitting the image into 128 x 128 regions and taking the Fourier Transform of each
section
F=zeros(128,128);
for i=500:128:1396
for j=500:128:1396
T = A(i:i+127,j:j+127);
P = (log(abs(fft2(T))).^2);
F = F+P;
end
end
% Averaging the sections and normalizing the image by pixel size. For Agfa CR system,
the pixel area normalization is 0.17*0.17, and 0.16*0.16 for Canon DR system.
K=(F/64)*((.17*.17)/(128*128));
% Flipping the image to ensure that it is displayed correctly
H(1:63,1:63)=fliplr(flipud(K(1:63,1:63)));
H(64:128,1:63)=fliplr(flipud(K(64:128,1:63)));
H(1:63,64:128)=fliplr(flipud(K(1:63,64:128)));
H(64:128,64:128)=fliplr(flipud(K(64:128,64:128)));
% Image of 2D NPS
figure(2);
colormap gray;
imagesc(H);
%Calculating the 1D NPS
% Determining the size of the 2D NPS image
[MA,NA] = size(H);
CXA = [NA/2:NA];
[M1A,N2A] = size(CXA);
%Selecting rows in the 2D NPS image to use for the 1D NPS curve
CY1 = ones(M1A,N2A)*(65);
CY2 = ones(M1A,N2A)*(66);
CY3 = ones(M1A,N2A)*(67);
CY4 = ones(M1A,N2A)*(68);
% Slices of the 2D NPS image adjacent to the X axis
LSF1 = improfile(H,CXA,CY1);
LSF2 = improfile(H,CXA,CY2);
LSF3 = improfile(H,CXA,CY3);
LSF4 = improfile(H,CXA,CY4);
% Averaging 1D NPS line segments
92
LSF=(LSF1+LSF2+LSF3+LSF4)/4;
% Plotting 1D NPS
figure(3);
plot(LSF,'red');
% Writing 1D NPS data to file.
file=input('Filename?','s')
DLMWRITE(file,LSF,'/t')
APPENDIX C
NOISE POWER SPECTRUM GRAPHS
50 kVp 0.6 mAs
1.20E-04
50 kVp 1.0 mAs
50 kVp 5.0 mAs
50 kVp 10.0 mAs
50 kVp 20.0 mAs
1.00E-04
50 kVp 32.0 mAs
50 kVp 40.0 mAs
55 kVp 0.6 mAs
55 kVp 1.0 mAs
8.00E-05
55 kVp 5.0 mAs
55 kVp 20.0 mAs
2
NPS (mm )
55 kVp 10.0 mAs
55 kVp 32.0 mAs
6.00E-05
60 kVp 0.6 mAs
60 kVp 1.0 mAs
60 kVp 5.0 mAs
60 kVp 10.0 mAs
4.00E-05
60 kVp 20.0 mAs
65 kVp 0.6 mAs
65 kVp 1.0 mAs
65 kVp 5.0 mAs
2.00E-05
65 kVp 10.0 mAs
65 kVp 20.0 mAs
70 kVp 0.6 mAs
70 kVp 1.0 mAs
0.00E+00
0.0
0.5
1.0
1.5
Frequency (Cycles/mm)
2.0
2.5
3.0
70 kVp 5.0 mAs
70 kVp 10.0 mAs
Figure C-1. The NPS vs. frequency for the Agfa CR system at a 40 inch SID without
using the grid
93
94
1.40E-04
50 kVp 0.6 mAs
50 kVp 1.0 mAs
50 kVp 5.0 mAs
50 kVp 10.0 mAs
1.20E-04
50 kVp 20.0 mAs
50 kVp 32.0 mAs
50 kVp 40.0 mAs
1.00E-04
55 kVp 0.6 mAs
55 kVp 1.0 mAs
55 kVp 10.0 mAs
8.00E-05
2
NPS (mm )
55 kVp 5.0 mAs
55 kVp 20.0 mAs
55 kVp 32.0 mAs
60 kVp 0.6 mAs
6.00E-05
60 kVp 1.0 mAs
60 kVp 5.0 mAs
60 kVp 10.0 mAs
4.00E-05
60 kVp 20.0 mAs
65 kVp 0.6 mAs
65 kVp 1.0 mAs
65 kVp 5.0 mAs
2.00E-05
65 kVp 10.0 mAs
65 kVp 20.0 mAs
70 kVp 0.6 mAs
0.00E+00
0
0.5
1
1.5
Frequency (cycles/mm)
2
2.5
3
70 kVp 1.0 mAs
70 kVp 5.0 mAs
70 kVp 10.0 mAs
Figure C-2. The NPS vs. frequency for the Agfa CR system at a 40 inch SID using the
grid
95
1.20E-04
50 kVp 0.6 mAs
50 kVp 1 mAs
50 kVp 5 mAs
50 kVp 10 mAs
1.00E-04
50 kVp 20 mAs
50 kVp 32 mAs
50 kVp 40 mAs
55 kVp 0.6 mAs
8.00E-05
55 kVp 1 mAs
55 kVp 10 mAs
2
NPS (mm )
55 kVp 5 mAs
55 kVp 20 mAs
6.00E-05
55 kVp 32 mAs
60 kVp 0.6 mAs
60 kVp 1 mAs
60 kVp 5 mAs
4.00E-05
60 kVp 10 mAs
60 kVp 20 mAs
65 kVp 0.6 mAs
65 kVp 1 mAs
2.00E-05
65 kVp 5 mAs
65 kVp 10 mAs
65 kVp 20 mAs
70 kVp 0.6 mAs
0.00E+00
0
0.5
1
1.5
Frequency (cycles/mm)
2
2.5
3
70 kVp 1 mAs
70 kVp 5 mAs
70 kVp 10 mAs
Figure C-3. The NPS vs. frequency for the Canon system at a 40 inch SID using the grid
96
70 kVp 0.6 mAs
1.20E-04
70 kVp 1.0 mAs
70 kVp 5.0 mAs
70 kVp 10.0 mAs
1.00E-04
70 kVp 20.0 mAs
75 kVp 0.6 mAs
75 kVp 1.0 mAs
8.00E-05
75 kVp 5.0 mAs
75 kVp 20.0 mAs
2
NPS (mm )
75 kVp 10.0 mAs
6.00E-05
80 kVp 0.6 mAs
80 kVp 1.0 mAs
80 kVp 5.0 mAs
80 kVp 10.0 mAs
4.00E-05
80 kVp 20.0 mAs
85 kVp 0.6 mAs
85 kVp 1.0 mAs
2.00E-05
85 kVp 5.0 mAs
85 kVp 10.0 mAs
85 kVp 20.0 mAs
0.00E+00
0
0.5
1
1.5
2
2.5
3
frequency (cycles/mm)
Figure C-4. The NPS vs. frequency for the Agfa CR system at a 72 inch SID without
using the grid
97
70 kVp 0.6 mAs
1.40E-04
70 kVp 1.0 mAs
70 kVp 5.0 mAs
1.20E-04
70 kVp 10.0 mAs
70 kVp 20.0 mAs
75 kVp 0.6 mAs
1.00E-04
75 kVp 1.0 mAs
75 kVp 10.0 mAs
8.00E-05
75 kVp 20.0 mAs
2
NPS (mm )
75 kVp 5.0 mAs
80 kVp 0.6 mAs
80 kVp 1.0 mAs
6.00E-05
80 kVp 5.0 mAs
80 kVp 10.0 mAs
80 kVp 20.0 mAs
4.00E-05
85 kVp 0.6 mAs
85 kVp 1.0 mAs
2.00E-05
85 kVp 5.0 mAs
85 kVp 10.0 mAs
85 kVp 20.0 mAs
0.00E+00
0
0.5
1
1.5
2
2.5
3
frequency (cycles/mm)
Figure C-5. The NPS vs. frequency for the Agfa CR system at a 72 inch SID using the
grid
98
1.20E-04
70 kVp 0.6 mAs
70 kVp 1 mAs
70 kVp 5 mAs
70 kVp 10 mAs
1.00E-04
70 kVp 20 mAs
70 kVp 32 mAs
75 kVp 0.6 mAs
75 kVp 1 mAs
8.00E-05
75 kVp 5 mAs
75 kVp 20 mAs
2
NPS (mm )
75 kVp 10 mAs
75 kVp 32 mAs
6.00E-05
80 kvp 0.6 mas
80 kVp 1 mAs
80 kVp 5 mAs
4.00E-05
80 kVp 10 mAs
80 kVp 20 mAs
80 kVp 32 mAs
85 kVp 0.6 mAs
2.00E-05
85 kVp 1 mAs
85 kVp 5 mAs
85 kVp 10 mAs
85 kVp 20 mAs
0.00E+00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
frequency (cycles/mm)
Figure C-6. The NPS vs. frequency for the Canon DR system at a 72 inch SID using the
grid
99
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
50 kVp
55 kVp
0.00E+00
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure C-7. For the Agfa CR system at a 40 inch SID without using the grid, the area
under the NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
100
3.50E-04
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
50 kVp
55 kVp
60 kVp
0.00E+00
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure C-8. For the Agfa CR system at a 40 inch SID using the grid, the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
101
3.50E-04
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
50 kVp
55 kVp
0.00E+00
60 kVp
0.6 mAs
1.0 mAs
65 kVp
5.0 mAs
10.0 mAs
20.0 mAs
70 kVp
32.0 mAs
40.0 mAs
Figure C-9. For the Canon DR system at a 40 inch SID using the grid , the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
102
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
85 kVp
80 kVp
0.00E+00
75 kVp
0.6 mAs
1 mAs
5 mAs
70 kVp
10 mAs
20 mAs
Figure C-10. For the Agfa CR system at a 72 inch SID without using the grid, the area
under the NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
103
3.50E-04
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
85 kVp
80 kVp
0.00E+00
75 kVp
0.6 mAs
1 mAs
5 mAs
70 kVp
10 mAs
20 mAs
Figure C-11. For the Agfa CR system at a 72 inch SID using the grid, the area under the
NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
104
3.00E-04
2.50E-04
iNPS
2.00E-04
1.50E-04
1.00E-04
5.00E-05
70 kVp
75 kVp
0.00E+00
0.6 mAs
80 kVp
1.0 mAs
5.0 mAs
10.0 mAs
85 kVp
20.0 mAs
32.0 mAs
Figure C-12. For the Canon DR system at a 72 inch SID using the grid, the area under
the NPS curve (iNPS) vs. radiographic technique (kVp and mAs)
APPENDIX D
INTEGRAL DETECTIVE QUANTUM EFFICIENCY GRAPHS
6.00
5.00
IDQE (1/mm)
2
4.00
3.00
2.00
1.00
50 kVp
55 kVp
0.00
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure D-1. For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.
radiographic technique (kVp and mAs).
.
105
106
5.00
4.50
4.00
IDQE (1/mm)2
3.50
3.00
2.50
2.00
1.50
1.00
50 kVp
0.50
55 kVp
0.00
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure D-2. For the Agfa CR system at a 40 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs).
107
8.000
7.000
6.000
IDQE (1/mm)2
5.000
4.000
3.000
2.000
1.000
50 kVp
55 kVp
0.000
60 kVp
0.6 mAs
1 mAs
65 kVp
5 mAs
10 mAs
20 mAs
70 kVp
32 mAs
40 mAs
Figure D-3. For the Canon DR system at a 40 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs).
108
4.00
3.50
3.00
IDQE (1/mm)2
2.50
2.00
1.50
1.00
70 kVp
0.50
75 kVp
0.00
80 kVp
0.6 mAs
1 mAs
5 mAs
85 kVp
10 mAs
20 mAs
Figure D-4. For the Agfa CR system at a 72 inch SID without using the grid, IDQE vs.
radiographic technique (kVp and mAs)
109
3.50
3.00
IDQE (1/mm)2
2.50
2.00
1.50
1.00
0.50
70 kVp
75 kVp
0.00
80 kVp
0.6 mAs
1 mAs
5 mAs
85 kVp
10 mAs
20 mAs
Figure D-5. For the Agfa CR system at a 72 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs).
110
7.00
6.00
IDQE (1/mm)2
5.00
4.00
3.00
2.00
1.00
70 kVp
75 kVp
0.00
0.6 mAs
80 kVp
1 mAs
5 mAs
10 mAs
85 kVp
20 mAs
32 mAs
Figure D-6. For the Canon DR system at a 72 inch SID using the grid, IDQE vs.
radiographic technique (kVp and mAs)
111
5.50
5.00
IDQE (1/mm)2
4.50
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
3.00
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
Air Kerma (mGy)
Figure D-7. For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.
Air Kerma [mGy] at the image receptor
112
5.00
4.50
IDQE (1/mm)
2
4.00
3.50
50 kVp
3.00
55 kVp
60 kVp
65 kVp
70 kVp
2.50
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Air Kerma (mGy)
Figure D-8. For the Agfa CR system at a 40 inch SID using the grid, IDQE vs. Air
Kerma [mGy] at the Image Receptor
113
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
50 kVp
5.000
55 kVp
60 kVp
4.500
65 kVp
4.000
3.500
0.00E+00
70 kVp
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
Air Kerma (mGy)
Figure D-9. For the Canon DR system at a 40 inch SID using the gridm, IDQE vs. Air
Kerma [mGy] at the image receptor
114
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
85 kVp
2.60
2.40
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Air Kerma (mGy)
Figure D-10. For the Agfa CR system at a 72 inch SID without using the grid ,IDQE vs.
Air Kerma [mGy] at image receptor
115
3.40
3.20
IDQE (1/mm)2
3.00
2.80
2.60
70 kVp
75 kVp
2.40
80 kVp
85 kVp
2.20
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
Air Kerma (mGy)
Figure D-11. For the Agfa CR system at a 72 inch SID using the grid, IDQE vs. Air
Kerma [mGy] at the image receptor
116
6.50
6.00
IDQE (1/mm)2
5.50
5.00
4.50
4.00
70 kVp
75 kVp
80 kVp
3.50
85 kVp
3.00
0.00E+00
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Air Kerma (mGy)
Figure D-12. For the Canon DR system at a 72 inch SID using the grid, IDQE vs. Air
Kerma [mGy] at the image receptor
117
5.50
5.00
IDQE (1/mm)2
4.50
4.00
3.50
50 kVp
55 kVp
60 kVp
3.00
65 kVp
70 kVp
2.50
1.00E-03
1.00E-02
1.00E-01
1.00E+00
Log Air Kerma (mGy)
Figure D-13. For the Agfa CR system at 40 inch SID without using the grid, IDQE vs.
Log Air Kerma at the image receptor [mGy]
118
5.00
4.50
IDQE (1/mm)
2
4.00
3.50
50 kVp
55 kVp
3.00
60 kVp
65 kVp
70 kVp
2.50
0.00
0.01
0.10
1.00
Log (Air Kerma) [mGy]
Figure D-14. For the Agfa CR system at a 40 inch SID using the grid, IDQE vs. Log Air
Kerma [mGy] at the image receptor
119
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
5.000
50 kVp
55 kVp
4.500
60 kVp
65 kVp
4.000
70 kVp
3.500
1.00E-03
1.00E-02
1.00E-01
1.00E+00
Log Air Kerma (mGy)
Figure D-15. For the Canon DR system at a 40 inch SID using the grid, IDQE vs. Log
Air Kerma [mGy] at the image receptor
120
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
2.60
85 kVp
2.40
0.00
0.01
0.10
1.00
Log Air Kerma (mGy)
Figure D-16. For the Agfa CR system at 72 inch SID without using the grid, IDQE vs.
Log Air Kerma [mGy] at the image receptor
121
3.40
3.20
IDQE (1/mm)
2
3.00
2.80
2.60
70 kVp
75 kVp
2.40
80 kVp
85 kVp
2.20
0.00
0.01
0.10
1.00
Log Air Kerma (mGy)
Figure D-17. For the Agfa CR system at a 72 inch SID using the grid, IDQE vs. Log Air
Kerma [mGy] at the image receptor
122
6.50
6.00
IDQE (1/mm)2
5.50
5.00
4.50
70 kVp
4.00
75 kVp
80 kVp
3.50
85 kVp
3.00
1.00E-03
1.00E-02
1.00E-01
1.00E+00
Log Air Kerma (mGy)
Figure D-18. For the Canon DR system at a 72 inch SID using the grid, IDQE vs. Log
Air Kerma [mGy] at the image receptor
123
5.50
5.00
IDQE (1/mm)2
4.50
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
3.00
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
9.00E-01
Entrance Skin Exposure (mGy)
Figure D-19. For the Agfa CR system at a 40 inch SID without using the grid, IDQE vs.
Entrance Skin Exposure for Newborn Patients
124
5.50
5.00
IDQE (1/mm)2
4.50
50 kVp
55 kVp
4.00
60 kVp
65 kVp
70 kVp
AEC
3.50
.75*AEC
.5*AEC
.25*AEC
3.00
0.00E+00
Log. (50
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
9.00E-01
Entrance Skin Expousre (mGy)
Figure D-20. Reduced AEC values for newborn patients for the Agfa CR system at a 40
inch SID without using the grid
125
5.00
4.50
IDQE (1/mm)
2
4.00
3.50
50 kVp
55 kVp
60 kVp
3.00
65 kVp
70 kVp
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Entrance Skin Exposure (mGy)
Figure D-21. IDQE vs. entrance skin exposure for newborn patients for the Agfa CR
system at a 40 inch SID using the grid
126
5.00
4.50
IDQE (1/mm)2
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
AEC
3.00
0.75*AEC
0.50*AEC
0.25*AEC
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Entrance Skin Expousre (mGy)
Figure D-22. Reduced AEC values for newborn patients for the Agfa CR system at a 40
inch SID using the grid
127
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
5.000
50 kVp
55 kVp
4.500
60 kVp
65 kVp
4.000
70 kVp
3.500
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
Entrance Skin Exposure (mGy)
Figure D-23. IDQE vs. entrance skin exposure for newborn patients For the Canon CR
system at a 40 inch SID using the grid
128
8.500
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
50 kVp
55 kVp
5.500
60 kVp
65 kVp
5.000
70 kVp
AEC
4.500
0.75*AEC
0.50*AEC
4.000
0.25*AEC
3.500
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
Entrance Skin Expousre (mGy)
Figure D-24. Reduced AEC values For Newborn Patients For the Canon CR system at a
40 inch SID using the grid
129
4.00
3.80
3.60
IDQE (1/mm)2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
2.60
85 kVp
2.40
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
Entrance Skin Exposure (mGy)
Figure D-25. IDQE vs. entrance skin exposure for newborn patients for the Agfa CR
system at a 72 inch SID without using the grid
130
4.00
3.80
3.60
IDQE (1/mm)2
3.40
70 kVp
3.20
75 kVp
80 kVp
3.00
85 kVp
AEC
2.80
0.75*AEC
0.50*AEC
2.60
2.40
0.00E+00
0.25*AEC
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
Entrance Skin Expousre (mGy)
Figure D-26. Reduced AEC values for newborn patients for the Agfa CR system at a 72
inch SID without using the grid
131
3.40
3.20
IDQE (1/mm)
2
3.00
2.80
2.60
70 kVp
2.40
75 kVp
80 kVp
2.20
85 kVp
2.00
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
Entrance Skin Exposure (mGy)
Figure D-27. IDQE vs. entrance skin exposure for newborn patients for the Agfa CR
system at a 72 inch SID using the grid
132
3.40
3.20
IDQE (1/mm)2
3.00
2.80
70 kVp
75 kVp
2.60
80 kVp
85 kVp
2.40
AEC
0.75*AEC
0.50*AEC
2.20
0.25*AEC
2.00
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
Entrance Skin Expousre (mGy)
Figure D-28. Reduced AEC values for newborn patients for the Agfa CR system at a 72
inch SID using the grid
133
6.50
6.00
IDQE (1/mm)2
5.50
5.00
4.50
70 kVp
4.00
75 kVp
80 kVp
3.50
85 kVp
3.00
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Exposure (mGy)
Figure D-29. IDQE vs. entrance skin exposure for newborn patients for the Canon DR
system at a 72 inch SID using the grid
134
7.00
6.50
6.00
IDQE (1/mm)2
5.50
70 kVp
75 kVp
5.00
80 kVp
85 kVp
4.50
AEC
0.75*AEC
4.00
0.50*AEC
0.25*AEC
3.50
3.00
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
9.00E-01
Entrance Skin Expousre (mGy)
Figure D-30. Reduced AEC values for newborn patients for the Canon DR system at a 72
inch SID using the grid
135
5.50
5.00
IDQE (1/mm)
2
4.50
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
3.00
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Entrance Skin Exposure (mGy)
Figure D-31. IDQE vs. Entrance Skin Exposure For One Year Old Patients For the Agfa
CR system at a 40 inch SID without using the grid
136
5.50
50 kVp
55 kVp
60 kVp
5.00
65 kVp
70 kVp
AEC
4.50
IDQE (1/mm)
2
0.75*AEC
0.50*AEC
0.25*AEC
4.00
3.50
3.00
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Entrance Skin Expousre (mGy)
Figure D-32. Reduced AEC vs. entrance skin exposure values for one year old patients
for the Agfa CR system at a 40 inch SID without using the grid
137
5.00
4.50
IDQE (1/mm)2
4.00
3.50
50 kVp
55 kVp
60 kVp
3.00
65 kVp
70 kVp
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
Entrance Skin Exposure (mGy)
Figure D-33. IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 40 inch SID using the grid
138
5.00
4.50
IDQE (1/mm)
2
4.00
50 kVp
55 kVp
60 kVp
3.50
65 kVp
70 kVp
AEC
3.00
0.75*AEC
0.50*AEC
0.25*AEC
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
1.80E+00
Entrance Skin Expousre (mGy)
Figure D-34. Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 40 inch SID using the grid
139
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
50 kVp
5.000
55 kVp
60 kVp
4.500
65 kVp
70 kVp
4.000
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
9.00E-01
Entrance Skin Exposure (mGy)
Figure D-35. IDQE vs. entrance skin exposure for one year old patients for the Canon CR
system at a 40 inch SID using the grid
140
9.500
50 kVp
55 kVp
60 kVp
8.500
65 kVp
70 kVp
AEC
7.500
0.75*AEC
IDQE (1/mm)2
0.50*AEC
0.25*AEC
Log (50
6.500
5.500
4.500
3.500
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00
2.50E+00
Entrance Skin Expousre (mGy)
Figure D-36. Reduced AEC values vs. entrance skin exposure for one year old patients
for the Canon CR system at a 40 inch SID using the grid
141
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
2.60
85 kVp
2.40
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Exposure (mGy)
Figure D-37. IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID without using the grid
142
4.00
3.80
3.60
IDQE (1/mm)2
3.40
3.20
70 kVp
75 kVp
3.00
80 kVp
85 kVp
2.80
AEC
0.75*AEC
2.60
0.50*AEC
0.25*AEC
2.40
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Expousre (mGy)
Figure D-38. Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 72 inch SID without using the grid
143
3.40
3.20
IDQE (1/mm)2
3.00
2.80
2.60
2.40
70 kVp
75 kVp
80 kVp
2.20
85 kVp
2.00
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Exposure (mGy)
Figure D-39. IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID using the grid
144
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
70 kVp
75 kVp
3.00
80 kVp
85 kVp
2.80
AEC
0.75*AEC
2.60
0.50*AEC
0.25*AEC
2.40
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Expousre (mGy)
Figure D-40. Reduced AEC values vs. entrance skin exposure for one year old patients
for the Agfa CR system at a 72 inch SID using the grid
145
6.50
6.00
IDQE (1/mm)
2
5.50
5.00
4.50
70 kVp
4.00
75 kVp
80 kVp
3.50
85 kVp
3.00
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01 4.50E-01 5.00E-01
Entrance Skin Exposure (mGy)
Figure D-41. IDQE vs. entrance skin exposure for one year old patients for the Canon DR
system at a 72 inch SID using the grid
146
7.50
7.00
6.50
IDQE (1/mm)
2
6.00
5.50
70 kVp
5.00
75 kVp
80 kVp
4.50
85 kVp
AEC
4.00
0.75*AEC
0.50*AEC
3.50
0.25*AEC
3.00
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
1.80E+00
Entrance Skin Expousre (mGy)
Figure D-42. Reduced AEC values vs. entrance skin exposure for one year old patients
for the Canon DR system at a 72 inch SID using the grid
147
5.50
5.00
IDQE (1/mm)2
4.50
4.00
50 kVp
55 kVp
60 kVp
3.50
65 kVp
70 kVp
3.00
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
Effective Dose (mSv)
Figure D-43. IDQE vs. Effective Dose For Newborn Patients For the Agfa CR system at
a 40 inch SID without using the grid
148
5.50
5.00
IDQE (1/mm)
2
4.50
50 kVp
55 kVp
4.00
60 kVp
65 kVp
70 kVp
AEC
3.50
.75*AEC
.5*AEC
.25*AEC
3.00
0.00E+00
Log. (50
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
Effective Dose (mSv)
Figure D-44. Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 40 inch SID without using the grid
149
5.00
4.50
IDQE (1/mm)2
4.00
3.50
50 kVp
55 kVp
3.00
60 kVp
65 kVp
70 kVp
2.50
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
Effective Dose (mSv)
Figure D-45. IDQE vs. Effective Dose For Newborn Patients For the Agfa CR system at
a 40 inch SID using the grid
150
5.00
4.50
IDQE (1/mm)2
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
AEC
3.00
0.75*AEC
0.50*AEC
0.25*AEC
2.50
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
Effective Dose (mSv)
Figure D-46. Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 40 inch SID using the grid
151
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
5.000
50 kVp
55 kVp
4.500
60 kVp
65 kVp
4.000
70 kVp
3.500
0.00E+00 2.00E-02 4.00E-02 6.00E-02 8.00E-02 1.00E-01 1.20E-01 1.40E-01 1.60E-01 1.80E-01 2.00E-01
Effective Dose (mSv)
Figure D-47. IDQE vs. Effective Dose for newborn patients for the Canon CR system at a
40 inch SID using the grid
152
8.500
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
50 kVp
55 kVp
5.500
60 kVp
65 kVp
5.000
70 kVp
AEC
4.500
0.75*AEC
0.50*AEC
4.000
0.25*AEC
3.500
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
Effective Dose (mSv)
Figure D-48. Reduced AEC values vs. effective dose for newborn patients for the Canon
CR system at a 40 inch SID using the grid
153
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
2.60
2.40
0.00E+00
85 kVp
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Effective Dose (mSv)
Figure D-49. IDQE vs. Effective Dose for newborn patients for the Agfa CR system at a
72 inch SID without using the grid
154
4.00
3.80
3.60
IDQE (1/mm)2
3.40
70 kVp
3.20
75 kVp
80 kVp
3.00
85 kVp
AEC
2.80
0.75*AEC
0.50*AEC
2.60
2.40
0.00E+00
0.25*AEC
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Effective Dose (mSv)
Figure D-50. Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 72 inch SID without using the grid
155
3.40
3.20
IDQE (1/mm)2
3.00
2.80
2.60
70 kVp
2.40
75 kVp
80 kVp
2.20
2.00
0.00E+00
85 kVp
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Effective Dose (mSv)
Figure D-51. IDQE vs. effective dose for newborn patients for the Agfa CR system at a
72 inch SID using the grid
156
3.40
3.20
IDQE (1/mm)2
3.00
2.80
70 kVp
75 kVp
2.60
80 kVp
85 kVp
2.40
AEC
0.75*AEC
0.50*AEC
2.20
0.25*AEC
2.00
0.00E+00
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Effective Dose (mSv)
Figure D-52. Reduced AEC values vs. effective dose for newborn patients for the Agfa
CR system at a 72 inch SID using the grid
157
6.50
6.00
IDQE (1/mm)
2
5.50
5.00
4.50
70 kVp
4.00
75 kVp
80 kVp
3.50
3.00
0.00E+00
85 kVp
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01
1.20E-01
1.40E-01
1.60E-01
Effective Dose (mSv)
Figure D-53. IDQE vs. Effective Dose for Newborn Patients for the Canon DR system at
a 72 inch SID using the grid
158
7.50
7.00
6.50
6.00
IDQE (1/mm)2
70 kVp
75 kVp
5.50
80 kVp
5.00
85 kVp
AEC
4.50
0.75*AEC
0.50*AEC
4.00
0.25*AEC
3.50
3.00
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
Effective Dose (mSv)
Figure D-54. Reduced AEC values vs. effective dose for newborn patients for the Canon
DR system at a 72 inch SID using the grid
159
5.50
5.00
IDQE (1/mm)2
4.50
4.00
50 kVp
55 kVp
3.50
60 kVp
65 kVp
70 kVp
3.00
0.00E+00 1.00E-01 2.00E-01 3.00E-01 4.00E-01 5.00E-01 6.00E-01 7.00E-01 8.00E-01 9.00E-01 1.00E+00
Effective Dose (mSv)
Figure D-55. IDQE vs. Effective Dose for One Year Old Patients for the Agfa CR system
at a 40 inch SID without using the grid
160
5.50
50 kVp
55 kVp
60 kVp
5.00
65 kVp
70 kVp
AEC
4.50
IDQE (1/mm)2
0.75*AEC
0.50*AEC
0.25*AEC
4.00
3.50
3.00
0.00E+00 1.00E-01 2.00E-01 3.00E-01 4.00E-01 5.00E-01 6.00E-01 7.00E-01 8.00E-01 9.00E-01 1.00E+00
Effective Dose (mSv)
Figure D-56. Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 40 inch SID without using the grid
161
5.00
4.50
IDQE (1/mm)
2
4.00
3.50
50 kVp
55 kVp
60 kVp
3.00
65 kVp
70 kVp
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
Effective Dose (mSv)
Figure D-57. IDQE vs. effective dose for one year old patients for the Agfa CR system at
a 40 inch SID using the grid
162
5.00
4.50
IDQE (1/mm)2
4.00
50 kVp
55 kVp
60 kVp
3.50
65 kVp
70 kVp
AEC
3.00
0.75*AEC
0.50*AEC
0.25*AEC
2.50
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
Effective Dose (mSv)
Figure D-58. Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 40 inch SID using the grid
163
8.000
7.500
7.000
IDQE (1/mm)2
6.500
6.000
5.500
50 kVp
5.000
55 kVp
4.500
60 kVp
65 kVp
4.000
3.500
0.00E+00
70 kVp
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
Effective Dose (mSv)
Figure D-59. IDQE vs. entrance skin exposure for one year old patients for the Canon CR
system at a 40 inch SID using the grid
164
9.500
50 kVp
55 kVp
60 kVp
8.500
65 kVp
70 kVp
AEC
7.500
0.75*AEC
IDQE (1/mm)
2
0.50*AEC
0.25*AEC
Log (50
6.500
5.500
4.500
3.500
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
1.80E+00
Effective Dose (mSv)
Figure D-60. Reduced AEC values vs. effective dose for one year old patients for the
Canon CR system at a 40 inch SID using the grid
165
4.00
3.80
3.60
IDQE (1/mm)
2
3.40
3.20
3.00
70 kVp
2.80
75 kVp
80 kVp
2.60
2.40
0.00E+00
85 kVp
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
Effective Dose (mSv)
Figure D-61. IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID without using the grid
166
4.00
3.80
3.60
IDQE (1/mm)2
3.40
3.20
70 kVp
75 kVp
3.00
80 kVp
85 kVp
2.80
AEC
0.75*AEC
2.60
0.50*AEC
0.25*AEC
2.40
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
Effective Dose (mSv)
Figure D-62. Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 72 inch SID without using the grid
167
3.40
3.20
IDQE (1/mm)
2
3.00
2.80
2.60
70 kVp
2.40
75 kVp
80 kVp
2.20
85 kVp
2.00
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
1.60E+00
1.80E+00
Effective Dose (mSv)
Figure D-63. IDQE vs. entrance skin exposure for one year old patients for the Agfa CR
system at a 72 inch SID using the grid
168
3.60
3.40
3.20
IDQE (1/mm)2
3.00
2.80
70 kVp
75 kVp
2.60
80 kVp
85 kVp
2.40
AEC
0.75*AEC
0.50*AEC
2.20
0.25*AEC
2.00
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00
2.50E+00
3.00E+00
Effective Dose (mSv)
Figure D-64. Reduced AEC values vs. effective dose for one year old patients for the
Agfa CR system at a 72 inch SID using the grid
169
6.50
6.00
IDQE (1/mm)
2
5.50
5.00
4.50
70 kVp
4.00
75 kVp
80 kVp
3.50
85 kVp
3.00
0.00E+00
2.00E-01
4.00E-01
6.00E-01
8.00E-01
1.00E+00
1.20E+00
1.40E+00
Effective Dose (mSv)
Figure D-65. IDQE vs. entrance skin exposure for one year old patients for the Canon DR
system at a 72 inch SID using the grid
170
7.00
6.50
6.00
IDQE (1/mm)2
5.50
5.00
70 kVp
75 kVp
4.50
80 kVp
85 kVp
4.00
AEC
0.75*AEC
0.50*AEC
3.50
0.25*AEC
3.00
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00
2.50E+00
3.00E+00
Effective Dose (mSv)
Figure D-66. Reduced AEC values vs. effective dose for one year old patients for the
Canon DR system at a 72 inch SID using the grid
APPENDIX E
COEFFICIENTS FOR IDQE EQUATIONS
Table E- 1. Coefficients for the Agfa CR system at a 40 inch SID without use of the grid
50 kVp
55 kVp
60 kVp
65 kVp
70 kVp
Slope
0.429
0.3891
0.3603
0.2878
0.2844
Exposure
to the Plate
5.6917
5.2301
4.838
4.2613
4.1041
Entrance Skin Exposure
Newborn One Year Old
5.5523
5.4449
5.1037
5.0062
4.7209
4.6307
4.3372
4.2619
4.1754
4.101
Effective Dose
Newborn One Year Old
6.1972
6.1812
5.7343
5.3901
5.1805
4.7383
4.7152
4.3087
4.5413
4.0077
Table E-2. Coefficients for the Agfa CR system at a 40 inch SID with use of the grid
50 kVp
55 kVp
60 kVp
65 kVp
70 kVp
Slope
0.4206
0.3897
0.369
0.3445
0.3032
Exposure
to the Plate
5.7185
5.2394
4.9039
4.5988
4.2746
Entrance Skin Exposure
Newborn
One Year Old
4.9176
4.7972
4.5202
4.4087
4.2467
4.1411
4.0027
3.9041
3.7639
3.6771
Effective Dose
Newborn One Year Old
5.563
5.5472
5.1638
4.8191
4.7287
4.2759
4.4467
3.9808
4.1464
3.6022
Table E-3. Coefficients for the Canon DR system at a 40 inch SID with the use of the
grid
50 kVp
55 kVp
60 kVp
65 kVp
70 kVp
Slope
0.8758
0.796
0.7754
0.6853
0.6571
Exposure
to the Plate
9.9513
9.0601
8.6114
7.862
7.5363
Entrance Skin Exposure
Newborn One Year Old
8.2979
8.064
7.6041
7.3916
7.2429
7.0358
6.6875
6.5045
6.4402
6.2647
Effective Dose
Newborn One Year Old
9.6274
9.5946
8.9058
8.2017
8.2431
7.2917
7.5595
6.6327
7.2585
6.079
Table E-4. Coefficients for the Agfa CR system at a 72 inch SID without the use of the
grid
70 kVp
75 kVp
80 kVp
85 kVp
Slope
0.3282
0.3138
0.2922
0.261
Exposure
to the Plate
4.391
4.2141
4.0137
3.8063
Entrance Skin Exposure
Newborn One Year Old
4.3339
4.2928
4.1595
4.1203
3.9628
3.9263
3.7608
3.7282
171
Effective Dose
Newborn One Year Old
4.7832
4.1104
4.5792
3.8326
4.3221
3.682
4.026
3.4111
Table E-5. Coefficients for the Agfa CR system at a 72 inch SID with the use of the grid
70 kVp
75 kVp
80 kVp
85 kVp
Slope
0.2482
0.2269
0.2203
0.2011
Exposure
to the Plate
3.9291
3.7149
3.5909
3.4079
Entrance Skin Exposure
Newborn One Year Old
3.6386
3.6065
3.4585
3.4292
3.3468
3.3184
3.1915
3.1655
Effective Dose
Newborn One Year Old
3.9794
3.4705
3.7629
3.2231
3.6186
3.136
3.3965
2.9229
Table E-6. Coefficients for the Canon DR system at a 72 inch SID with the use of the
grid
70 kVp
75 kVp
80 kVp
85 kVp
Slope
0.6759
0.6616
0.6266
0.6155
Exposure
to the Plate
7.6576
7.3765
7.066
6.8828
Entrance Skin Exposure
Newborn One Year Old
6.8678
6.7819
6.6302
6.5462
6.3731
6.2935
6.2216
6.1435
172
Effective Dose
Newborn One Year Old
9.6274
9.5946
8.9058
8.2017
8.2431
7.2917
7.5595
6.6327
APPENDIX F
EFFECTIVE DOSE CALCULATIONS
This data is the calculation of effective dose to the anthropomorphic newborn and
one-year-old phantoms from chest examinations from the tube in Room 1 for the Agfa
CR system and the tube in Room 5 for the Canon DR system at Shands at the University
of Florida.
The MOSFET dosimeters were calibrated by exposing the dosimeters until a 200
mV reading was obtained. This number is divided by the exposure(mR) to get a
MOSFET Calibration Factor (CF) in mV/mR.
The dose conversion factor (DCF) is a ratio of the average mass energy absorption
coefficient of tissue to air. The ratios of soft tissue/air, bone/air and lung/air is 1.014,
3.078 and 1.051, respectively.
The organ-absorbed dose (OAD) in mGy for each organ sited was calculated by
taking the mV reading for the MOSFET and dividing it by the calibration factor, then
mulitiplying it by 0.876 to convert dose in air. This number is then multiplied by the
DCF. This is shown in Equation F-1.
DTissue
 µen 

ρ Tissue 1

= 0.876 ⋅
⋅
⋅ mV
CF
 µen 

ρ  Si

(F-1)
The active bone marrow was calculated by multiplying the MOSFET value by the
DCF corresponding to soft tissue which is illustrated in Equation F-2. The absorbed dose
of each of the skeletal components was then multiplied by the fraction of active bone
173
174
marrow assigned to the MOSFET (BMW). These values were then summed together to
get the total absorbed dose to the active marrow shown in Equation F-3.
DBoneMarrowSite
 µ en 

ρ  SoftTissue 1

= 0.876 ⋅
⋅
⋅ mV
CF
 µ en 

ρ  Si

DTotalBoneMarrow =
∑D
BMSite
(mGy ) * BMW
(F-2)
(F-3)
Sites
The bone surface was calculated by multiplying the MOSFET value by the DCF
corresponding to bone which is illustrated in Equation F-4. The absorbed dose of each
skeletal components was then multiplied by the fraction of active bone marrow assigned
to the MOSFET (BMW). These values were then summed together to get the total
absorbed dose to the active marrow shown in Equation F-5.
DBoneSurfaceSite
 µ en 

ρ  Bone 1

= 0.876 ⋅
⋅
⋅ mV
CF
 µ en 

ρ  Si

DTotalBoneSurface =
∑D
BSSite
(mGy ) * BMW
(F-4)
(F-5)
Sites
The organ-absorbed dose values for the remainder organs were the average of the
liver, stomach, bladder and colon organ-absorbed doses. The organ-absorbed dose values
for the surface were the average of the MOSFET located on the surface such as breast,
back, eye, etc.
The effective dose (mSv) was calculated by multiplying the organ-absorbed dose
by the tissue weighting factor (TWF) for each organ, then summing all the organ sites
together as shown in Equation F-6. The radiation weighting factor, wr is one for photons.
175
E (mSv) =
∑D
organ
(mGy ) * wr * TWF
(F-6)
Organ
Table F-1. Newborn effective doses for Agfa CR system at 50 kVp
Male
0.092 mSv
Female
0.109 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
1.1
29.29
1.014
0.0
0.0
1.2
0.6
1.8
0.0
0.0
0.0
0.3
0.0
0.7
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
0.3
0.3
0.4
0.0
0.1
0.2
0.0
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.334
0.000
0.000
0.000
0.330
0.169
0.543
0.000
0.000
0.000
0.078
0.000
0.212
0.085
0.086
0.084
0.122
0.000
0.031
0.058
0.000
0.058
0.217
0.142
0.150
TWF
OAD*TWF
0.05
0.12
0.017
0.000
0.05
0.05
0.027
0.000
0.20
0.12
0.05
0.12
0.20
0.000
0.009
0.000
0.025
0.017
0.05
0.002
0.12
0.01
0.01
0.01
0.007
0.002
0.001
0.002
176
Table F-1. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
0.6
0.0
0.4
0.0
OAD
[mGy]
BMW
OAD*BMW
0.330
0.169
0.000
0.122
0.000
0.0779
0.0779
0.2191
0.1588
0.1470
0.026
0.013
0.000
0.019
0.000
Total Bone Marrow absorbed dose (mGy)
0.058
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
0.6
0.0
0.4
0.0
OAD
[mGy]
BSW
OAD*BSW
1.001
0.512
0.000
0.370
0.000
0.0980
0.0980
0.2190
0.1850
0.1160
0.098
0.050
0.000
0.069
0.000
Total Bone Surface absorbed dose (mGy)
0.216
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
177
Table F-2. Newborn effective doses for Agfa CR system at 55 kVp
Male
0.119 mSv
Female
0.120 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
0.1
29.29
1.014
0.1
0.5
0.0
0.9
2.1
0.3
0.0
0.0
0.1
0.3
1.2
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
0.2
0.0
0.3
0.4
0.3
0.3
0.3
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.030
0.084
0.029
0.140
0.000
0.253
0.633
0.085
0.000
0.000
0.026
0.089
0.363
0.029
0.058
0.000
0.092
0.130
0.094
0.087
0.082
0.053
0.172
0.107
0.201
TWF
OAD*TWF
0.05
0.12
0.002
0.010
0.05
0.05
0.032
0.004
0.20
0.12
0.05
0.12
0.20
0.000
0.003
0.004
0.044
0.006
0.05
0.005
0.12
0.01
0.01
0.01
0.006
0.002
0.001
0.002
178
Table F-2 Continued
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.0
0.9
0.0
0.3
0.4
OAD
[mGy]
BMW
OAD*BMW
0.000
0.253
0.000
0.092
0.130
0.0779
0.0779
0.2191
0.1588
0.1470
0.000
0.020
0.000
0.015
0.019
Total Bone Marrow absorbed dose (mGy)
0.053
32.34
31.62
28.70
29.12
27.29
DCF
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.0
0.9
0.0
0.3
0.4
OAD
[mGy]
BSW
OAD*BSW
0.000
0.767
0.000
0.278
0.395
0.0980
0.0980
0.2190
0.1850
0.1160
0.000
0.075
0.000
0.051
0.046
Total Bone Surface absorbed dose (mGy)
0.172
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
179
Table F-3. Newborn effective doses for Agfa CR system at 60 kVp
Male
0.195 mSv
Female
0.207 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
1.0
29.29
1.014
1.5
0.9
0.9
0.5
3.7
0.0
0.0
0.0
0.0
0.5
1.7
0.0
0.4
0.0
0.6
0.0
0.0
0.0
0.0
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.303
0.344
0.437
0.251
0.247
0.140
1.115
0.000
0.000
0.000
0.000
0.149
0.514
0.058
0.115
0.000
0.183
0.000
0.000
0.000
0.000
0.059
0.218
0.205
0.279
TWF
OAD*TWF
0.05
0.12
0.015
0.041
0.05
0.05
0.056
0.000
0.20
0.12
0.05
0.12
0.20
0.000
0.000
0.007
0.062
0.012
0.05
0.000
0.12
0.01
0.01
0.01
0.007
0.002
0.002
0.003
180
Table F-3. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.9
0.5
0.0
0.6
0.0
OAD
[mGy]
BMW
OAD*BMW
0.247
0.140
0.000
0.183
0.000
0.0779
0.0779
0.2191
0.1588
0.1470
0.019
0.011
0.000
0.029
0.000
Total Bone Marrow absorbed dose (mGy)
0.059
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.9
0.5
0.0
0.6
0.0
OAD
[mGy]
BSW
OAD*BSW
0.750
0.426
0.000
0.555
0.000
0.0980
0.0980
0.2190
0.1850
0.1160
0.074
0.042
0.000
0.103
0.000
Total Bone Surface absorbed dose (mGy)
0.218
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
181
Table F-4. Newborn effective doses for Agfa CR system at 65 kVp
Male
0.251 mSv
Female
0.263 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
1.7
29.29
1.014
1.2
1.3
1.5
1.0
3.8
0.0
0.0
0.0
0.1
0.1
2.8
0.0
0.4
0.0
0.1
0.6
0.0
0.0
0.0
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.515
0.356
0.350
0.363
0.412
0.281
1.145
0.000
0.000
0.000
0.026
0.030
0.847
0.058
0.115
0.000
0.031
0.195
0.000
0.000
0.000
0.088
0.292
0.295
0.286
TWF
OAD*TWF
0.05
0.12
0.026
0.043
0.05
0.05
0.057
0.000
0.20
0.12
0.05
0.12
0.20
0.000
0.003
0.001
0.102
0.012
0.05
0.000
0.12
0.01
0.01
0.01
0.011
0.003
0.003
0.003
182
Table F-4. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.5
1.0
0.0
0.1
0.6
OAD
[mGy]
BMW
OAD*BMW
0.412
0.281
0.000
0.031
0.195
0.0779
0.0779
0.2191
0.1588
0.1470
0.032
0.022
0.000
0.005
0.029
Total Bone Marrow absorbed dose (mGy)
0.088
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.5
1.0
0.0
0.1
0.6
OAD
[mGy]
BSW
OAD*BSW
1.251
0.853
0.000
0.093
0.593
0.0980
0.0980
0.2190
0.1850
0.1160
0.123
0.084
0.000
0.017
0.069
Total Bone Surface absorbed dose (mGy)
0.292
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
183
Table F-5. Newborn effective doses for Agfa CR system at 70 kVp
Male
0.318 mSv
Female
0.321 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
2.1
29.29
1.014
1.4
2.3
1.2
0.9
4.7
0.6
0.2
0.0
0.2
0.6
2.9
0.0
0.1
0.0
0.9
0.0
0.0
0.0
0.1
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.637
0.525
0.408
0.642
0.330
0.253
1.417
0.170
0.062
0.000
0.052
0.179
0.877
0.014
0.029
0.000
0.275
0.000
0.000
0.000
0.027
0.103
0.369
0.352
0.361
TWF
OAD*TWF
0.05
0.12
0.032
0.063
0.05
0.05
0.071
0.008
0.20
0.12
0.05
0.12
0.20
0.000
0.006
0.009
0.105
0.003
0.05
0.000
0.12
0.01
0.01
0.01
0.012
0.004
0.004
0.004
184
Table F-5. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
0.9
0.2
0.9
0.0
OAD
[mGy]
BMW
OAD*BMW
0.330
0.253
0.062
0.275
0.000
0.0779
0.0779
0.2191
0.1588
0.1470
0.026
0.020
0.014
0.044
0.000
Total Bone Marrow absorbed dose (mGy)
0.103
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
0.9
0.2
0.9
0.0
OAD
[mGy]
BSW
OAD*BSW
1.001
0.767
0.188
0.833
0.000
0.0980
0.0980
0.2190
0.1850
0.1160
0.098
0.075
0.041
0.154
0.000
Total Bone Surface absorbed dose (mGy)
0.369
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
185
Table F-6. Newborn effective doses for Agfa CR system at 75 kVp
Male
0.122 mSv
Female
0.139 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.2
2.1
0.7
1.6
2.1
0.2
1.2
0.0
0.0
0.3
0.0
0.3
0.3
0.3
1.5
0.5
0.0
0.0
3.3
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.061
0.612
0.195
0.439
0.590
0.060
0.339
0.000
0.000
0.078
0.000
0.091
0.086
0.084
0.458
0.163
0.000
0.000
0.901
0.085
0.404
0.177
0.620
0.063
0.240
TWF
OAD*TWF
0.05
0.003
0.05
0.05
0.003
0.017
0.2
0.12
0.05
0.12
0.000
0.009
0.000
0.011
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.017
0.048
0.021
0.006
0.001
0.002
186
Table F-5. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.6
2.1
0.0
1.5
0.5
OAD
[mGy]
BMW
OAD*BMW
0.439
0.590
0.000
0.458
0.163
0.0779
0.0779
0.2191
0.1588
0.1470
0.034
0.046
0.000
0.073
0.024
Total Bone Marrow absorbed dose (mGy)
0.177
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.6
2.1
0.0
1.5
0.5
OAD
[mGy]
BSW
OAD*BSW
1.334
1.791
0.000
1.389
0.494
0.0980
0.0980
0.2190
0.1850
0.1160
0.131
0.175
0.000
0.257
0.057
Total Bone Surface absorbed dose (mGy)
0.620
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
187
Table F-7. Newborn effective doses for Agfa CR system at 80 kVp
Male
0.201 mSv
Female
0.204 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.9
2.5
2.1
1.0
1.0
0.7
1.6
0.0
0.0
0.1
0.0
1.3
0.1
0.0
1.5
0.4
0.0
0.0
2.9
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.273
0.729
0.586
0.275
0.281
0.211
0.452
0.000
0.000
0.026
0.000
0.393
0.029
0.000
0.458
0.130
0.000
0.000
0.791
0.014
0.658
0.135
0.468
0.141
0.251
TWF
OAD*TWF
0.05
0.014
0.05
0.05
0.011
0.023
0.2
0.12
0.05
0.12
0.000
0.003
0.000
0.047
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.003
0.079
0.016
0.005
0.001
0.003
188
Table F-7. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.0
0.0
1.5
0.4
OAD
[mGy]
BMW
OAD*BMW
0.275
0.281
0.000
0.458
0.130
0.0779
0.0779
0.2191
0.1588
0.1470
0.021
0.022
0.000
0.073
0.019
Total Bone Marrow absorbed dose (mGy)
0.135
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.0
0.0
1.5
0.4
OAD
[mGy]
BSW
OAD*BSW
0.834
0.853
0.000
1.389
0.395
0.0980
0.0980
0.2190
0.1850
0.1160
0.082
0.084
0.000
0.257
0.046
Total Bone Surface absorbed dose (mGy)
0.468
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
189
Table F-8. Newborn effective doses for Agfa CR system at 85 kVp
Male
0.189 mSv
Female
0.183 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
1.0
2.3
1.5
1.0
1.7
0.4
2.1
0.1
0.1
0.0
0.0
0.8
0.0
0.0
2.2
0.6
0.2
0.1
2.5
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.303
0.671
0.419
0.275
0.478
0.121
0.594
0.031
0.033
0.000
0.000
0.242
0.000
0.000
0.671
0.195
0.063
0.029
0.682
0.000
0.545
0.201
0.690
0.109
0.216
TWF
OAD*TWF
0.05
0.015
0.05
0.05
0.006
0.030
0.2
0.12
0.05
0.12
0.007
0.000
0.000
0.029
0.05
0.003
0.2
0.12
0.12
0.01
0.01
0.01
0.000
0.065
0.024
0.007
0.001
0.002
190
Table F-8. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.7
0.1
2.2
0.6
OAD
[mGy]
BMW
OAD*BMW
0.275
0.478
0.031
0.671
0.195
0.0779
0.0779
0.2191
0.1588
0.1470
0.021
0.037
0.007
0.107
0.029
Total Bone Marrow absorbed dose (mGy)
0.201
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.7
0.1
2.2
0.6
OAD
[mGy]
BSW
OAD*BSW
0.834
1.450
0.094
2.037
0.593
0.0980
0.0980
0.2190
0.1850
0.1160
0.082
0.142
0.021
0.377
0.069
Total Bone Surface absorbed dose (mGy)
0.690
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
191
Table F-9. Newborn effective doses for Canon DR system at 50 kVp
Male
0.052 mSv
Female
0.061 mSv
Organ Sites
Liver
Average Lung
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Average Ovary
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
DCF
0.0
29.29
1.014
1.2
0.2
0.1
0.4
0.1
0.0
0.0
0.0
0.1
0.1
0.3
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
0.3
0.0
0.2
0.7
0.1
0.0
0.9
30.84
31.72
29.12
27.29
28.38
30.46
32.55
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.203
0.350
0.056
0.027
0.112
0.030
0.000
0.000
0.000
0.026
0.030
0.091
0.043
0.086
0.000
0.061
0.228
0.031
0.000
0.246
0.054
0.156
0.038
0.069
TWF
OAD*TWF
0.05
0.12
0.000
0.024
0.05
0.05
0.002
0.000
0.20
0.12
0.05
0.12
0.20
0.000
0.003
0.001
0.011
0.009
0.05
0.002
0.12
0.01
0.01
0.01
0.006
0.002
0.000
0.001
192
Table F-9. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.1
0.4
0.0
0.2
0.7
OAD
[mGy]
BMW
OAD*BMW
0.027
0.112
0.000
0.061
0.228
0.0779
0.0779
0.2191
0.1588
0.1470
0.002
0.009
0.000
0.010
0.033
Total Bone Marrow absorbed dose (mGy)
0.054
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.1
0.4
0.0
0.2
0.7
OAD
[mGy]
BSW
OAD*BSW
0.083
0.341
0.000
0.185
0.692
0.0980
0.0980
0.2190
0.1850
0.1160
0.008
0.033
0.000
0.034
0.080
Total Bone Surface absorbed dose (mGy)
0.156
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
193
Table F-10. Newborn effective doses for Canon DR system at 55 kVp
Male
0.076 mSv
Female
0.076 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.1
0.6
0.7
0.7
0.5
0.0
1.0
0.0
0.0
0.2
0.0
0.4
0.0
0.0
0.8
0.6
0.1
0.3
1.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.030
0.175
0.195
0.192
0.140
0.000
0.283
0.000
0.000
0.052
0.000
0.121
0.000
0.000
0.244
0.195
0.031
0.087
0.273
0.000
0.185
0.093
0.305
0.041
0.090
TWF
OAD*TWF
0.05
0.002
0.05
0.05
0.000
0.014
0.2
0.12
0.05
0.12
0.000
0.006
0.000
0.015
0.05
0.002
0.2
0.12
0.12
0.01
0.01
0.01
0.000
0.022
0.011
0.003
0.000
0.001
194
Table F-10. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.7
0.5
0.0
0.8
0.6
OAD
[mGy]
BMW
OAD*BMW
0.192
0.140
0.000
0.244
0.195
0.0779
0.0779
0.2191
0.1588
0.1470
0.015
0.011
0.000
0.039
0.029
Total Bone Marrow absorbed dose (mGy)
0.093
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.7
0.5
0.0
0.8
0.6
OAD
[mGy]
BSW
OAD*BSW
0.584
0.426
0.000
0.741
0.593
0.0980
0.0980
0.2190
0.1850
0.1160
0.057
0.042
0.000
0.137
0.069
Total Bone Surface absorbed dose (mGy)
0.305
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
195
Table F-11. Newborn effective doses for Canon DR system at 60 kVp
Male
0.138 mSv
Female
0.143 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
1.5
1.9
0.9
0.4
0.2
0.6
1.5
0.0
0.0
0.2
0.1
0.3
0.0
0.2
1.7
0.0
0.0
0.0
1.9
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.455
0.554
0.251
0.110
0.056
0.181
0.424
0.000
0.000
0.052
0.030
0.091
0.000
0.056
0.519
0.000
0.000
0.000
0.519
0.028
0.403
0.095
0.341
0.131
0.175
TWF
OAD*TWF
0.05
0.023
0.05
0.05
0.009
0.021
0.2
0.12
0.05
0.12
0.000
0.006
0.001
0.011
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.006
0.048
0.011
0.003
0.001
0.002
196
Table F-11. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.4
0.2
0.0
1.7
0.0
OAD
[mGy]
BMW
OAD*BMW
0.110
0.056
0.000
0.519
0.000
0.0779
0.0779
0.2191
0.1588
0.1470
0.009
0.004
0.000
0.082
0.000
Total Bone Marrow absorbed dose (mGy)
0.095
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.4
0.2
0.0
1.7
0.0
OAD
[mGy]
BSW
OAD*BSW
0.334
0.171
0.000
1.574
0.000
0.0980
0.0980
0.2190
0.1850
0.1160
0.033
0.017
0.000
0.291
0.000
Total Bone Surface absorbed dose (mGy)
0.341
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
197
Table F-12. Newborn effective doses for Canon DR system at 65 kVp
Male
0.108 mSv
Female
0.117 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.3
0.2
1.3
0.6
0.3
0.4
0.7
0.0
0.0
0.3
0.0
0.9
0.3
0.0
1.7
0.1
0.0
0.0
3.3
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.091
0.058
0.363
0.165
0.084
0.121
0.198
0.000
0.000
0.078
0.000
0.272
0.086
0.000
0.519
0.033
0.000
0.000
0.901
0.043
0.211
0.107
0.377
0.097
0.255
TWF
OAD*TWF
0.05
0.005
0.05
0.05
0.006
0.010
0.2
0.12
0.05
0.12
0.000
0.009
0.000
0.033
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.009
0.025
0.013
0.004
0.001
0.003
198
Table F-12. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.6
0.3
0.0
1.7
0.1
OAD
[mGy]
BMW
OAD*BMW
0.165
0.084
0.000
0.519
0.033
0.0779
0.0779
0.2191
0.1588
0.1470
0.013
0.007
0.000
0.082
0.005
Total Bone Marrow absorbed dose (mGy)
0.107
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
0.6
0.3
0.0
1.7
0.1
OAD
[mGy]
BSW
OAD*BSW
0.500
0.256
0.000
1.574
0.099
0.0980
0.0980
0.2190
0.1850
0.1160
0.049
0.025
0.000
0.291
0.011
Total Bone Surface absorbed dose (mGy)
0.377
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
199
Table F-13. Newborn effective doses for Canon DR system at 70 kVp
Male
0.162 mSv
Female
0.173 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.4
2.0
1.5
1.2
1.3
0.0
1.2
0.0
0.0
0.0
0.0
1.4
0.4
0.0
1.3
0.7
0.1
0.0
2.6
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.121
0.583
0.419
0.330
0.365
0.000
0.339
0.000
0.000
0.000
0.000
0.423
0.115
0.000
0.397
0.228
0.031
0.000
0.710
0.058
0.501
0.151
0.510
0.120
0.177
TWF
OAD*TWF
0.05
0.006
0.05
0.05
0.000
0.017
0.2
0.12
0.05
0.12
0.000
0.000
0.000
0.051
0.05
0.002
0.2
0.12
0.12
0.01
0.01
0.01
0.012
0.060
0.018
0.005
0.001
0.002
200
Table F-13. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
1.3
0.0
1.3
0.7
OAD
[mGy]
BMW
OAD*BMW
0.330
0.365
0.000
0.397
0.228
0.0779
0.0779
0.2191
0.1588
0.1470
0.026
0.028
0.000
0.063
0.033
Total Bone Marrow absorbed dose (mGy)
0.151
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.2
1.3
0.0
1.3
0.7
OAD
[mGy]
BSW
OAD*BSW
1.001
1.109
0.000
1.204
0.692
0.0980
0.0980
0.2190
0.1850
0.1160
0.098
0.109
0.000
0.223
0.080
Total Bone Surface absorbed dose (mGy)
0.510
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
201
Table F-14. Newborn effective doses for Canon DR system at 75 kVp
Male
0.122 mSv
Female
0.139 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.2
2.1
0.7
1.6
2.1
0.2
1.2
0.0
0.0
0.3
0.0
0.3
0.3
0.3
1.5
0.5
0.0
0.0
3.3
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.061
0.612
0.195
0.439
0.590
0.060
0.339
0.000
0.000
0.078
0.000
0.091
0.086
0.084
0.458
0.163
0.000
0.000
0.901
0.085
0.404
0.177
0.620
0.063
0.240
TWF
OAD*TWF
0.05
0.003
0.05
0.05
0.003
0.017
0.2
0.12
0.05
0.12
0.000
0.009
0.000
0.011
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.017
0.048
0.021
0.006
0.001
0.002
202
Table F-14. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.6
2.1
0.0
1.5
0.5
OAD
[mGy]
BMW
OAD*BMW
0.439
0.590
0.000
0.458
0.163
0.0779
0.0779
0.2191
0.1588
0.1470
0.034
0.046
0.000
0.073
0.024
Total Bone Marrow absorbed dose (mGy)
0.177
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.6
2.1
0.0
1.5
0.5
OAD
[mGy]
BSW
OAD*BSW
1.334
1.791
0.000
1.389
0.494
0.0980
0.0980
0.2190
0.1850
0.1160
0.131
0.175
0.000
0.257
0.057
Total Bone Surface absorbed dose (mGy)
0.620
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
203
Table F-15. Newborn effective doses for Canon DR system at 80 kVp
Male
0.201 mSv
Female
0.204 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
0.9
2.5
2.1
1.0
1.0
0.7
1.6
0.0
0.0
0.1
0.0
1.3
0.1
0.0
1.5
0.4
0.0
0.0
2.9
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.273
0.729
0.586
0.275
0.281
0.211
0.452
0.000
0.000
0.026
0.000
0.393
0.029
0.000
0.458
0.130
0.000
0.000
0.791
0.014
0.658
0.135
0.468
0.141
0.251
TWF
OAD*TWF
0.05
0.014
0.05
0.05
0.011
0.023
0.2
0.12
0.05
0.12
0.000
0.003
0.000
0.047
0.05
0.000
0.2
0.12
0.12
0.01
0.01
0.01
0.003
0.079
0.016
0.005
0.001
0.003
204
Table F-15. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.0
0.0
1.5
0.4
OAD
[mGy]
BMW
OAD*BMW
0.275
0.281
0.000
0.458
0.130
0.0779
0.0779
0.2191
0.1588
0.1470
0.021
0.022
0.000
0.073
0.019
Total Bone Marrow absorbed dose (mGy)
0.135
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.0
0.0
1.5
0.4
OAD
[mGy]
BSW
OAD*BSW
0.834
0.853
0.000
1.389
0.395
0.0980
0.0980
0.2190
0.1850
0.1160
0.082
0.084
0.000
0.257
0.046
Total Bone Surface absorbed dose (mGy)
0.468
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
205
Table F-16. Newborn effective doses for Canon DR system at 85 kVp
Male
0.189 mSv
Female
0.183 mSv
Organ Sites
Liver
Rt. Lung
Lt Lung
Rt. Arm
Lt Arm
Breast
Esophagus
Pelvis
Testes
Colon
Bladder
Stomach
Rt. Ovary
Lt. Ovary
Spine Middle
Skull
Thyroid
Rt. Eye
Back
Average Ovary
Average Lung
Marrow
Bone Surface
Remainder
Surface/Skin
MOSFET
CF
[mV]
[mR/mV]
1.0
2.3
1.5
1.0
1.7
0.4
2.1
0.1
0.1
0.0
0.0
0.8
0.0
0.0
2.2
0.6
0.2
0.1
2.5
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
32.55
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.303
0.671
0.419
0.275
0.478
0.121
0.594
0.031
0.033
0.000
0.000
0.242
0.000
0.000
0.671
0.195
0.063
0.029
0.682
0.000
0.545
0.201
0.690
0.109
0.216
TWF
OAD*TWF
0.05
0.015
0.05
0.05
0.006
0.030
0.2
0.12
0.05
0.12
0.007
0.000
0.000
0.029
0.05
0.003
0.2
0.12
0.12
0.01
0.01
0.01
0.000
0.065
0.024
0.007
0.001
0.002
206
Table F-16. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.7
0.1
2.2
0.6
OAD
[mGy]
BMW
OAD*BMW
0.275
0.478
0.031
0.671
0.195
0.0779
0.0779
0.2191
0.1588
0.1470
0.021
0.037
0.007
0.107
0.029
Total Bone Marrow absorbed dose (mGy)
0.201
32.34
31.62
28.70
29.12
27.29
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV]
DCF
Rt. Arm
Lt Arm
Pelvis
Spine Middle
Skull
1.0
1.7
0.1
2.2
0.6
OAD
[mGy]
BSW
OAD*BSW
0.834
1.450
0.094
2.037
0.593
0.0980
0.0980
0.2190
0.1850
0.1160
0.082
0.142
0.021
0.377
0.069
Total Bone Surface absorbed dose (mGy)
0.690
32.3377
31.619
28.7032
29.1228
27.2877
3.07787
3.07787
3.07787
3.07787
3.07787
207
Table F-17. One-Year-Old effective doses for Agfa CR system at 50 kVp
Male
0.079 mSv
Female
0.080 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.7
0.0
0.9
0.3
1.3
0.7
0.5
0.0
0.3
0.4
0.1
0.0
0.0
0.2
0.0
0.1
0.1
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.204
0.000
0.247
0.084
0.392
0.198
0.155
0.000
0.078
0.119
0.030
0.000
0.000
0.061
0.000
0.031
0.029
0.099
0.031
0.061
0.184
0.088
0.211
TWF
OAD*TWF
0.05
0.000
0.05
0.05
0.12
0.05
0.020
0.010
0.019
0.000
0.05
0.12
0.002
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.006
0.012
0.006
0.007
0.002
0.001
0.002
208
Table F-17. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.7
0.9
0.3
0.0
0.1
OAD
[mGy]
BMW
OAD*BMW
0.000
0.204
0.247
0.084
0.000
0.031
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.030
0.019
0.007
0.000
0.005
Total Bone Marrow absorbed dose (mGy)
0.061
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.7
0.9
0.3
0.0
0.1
OAD
[mGy]
BSW
OAD*BSW
0.000
0.606
0.734
0.250
0.000
0.093
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.070
0.072
0.025
0.000
0.017
Total Bone Surface absorbed dose (mGy)
0.184
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
209
Table F-18. One-Year-Old effective doses for Agfa CR system at 55 kVp
Male
0.131 mSv
Female
0.133 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.2
0.3
0.5
0.6
1.7
0.8
1.2
0.0
0.7
0.8
0.7
0.0
0.1
0.0
0.0
0.0
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.058
0.084
0.137
0.169
0.512
0.226
0.371
0.000
0.183
0.238
0.212
0.000
0.028
0.000
0.000
0.000
0.000
0.211
0.014
0.032
0.109
0.149
0.256
TWF
OAD*TWF
0.05
0.004
0.05
0.05
0.12
0.05
0.026
0.011
0.045
0.000
0.05
0.12
0.011
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.025
0.003
0.004
0.001
0.001
0.003
210
Table F-18. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.2
0.5
0.6
0.0
0.0
OAD
[mGy]
BMW
OAD*BMW
0.000
0.058
0.137
0.169
0.000
0.000
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.009
0.011
0.013
0.000
0.000
Total Bone Marrow absorbed dose (mGy)
0.032
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.2
0.5
0.6
0.0
0.0
OAD
[mGy]
BSW
OAD*BSW
0.000
0.173
0.408
0.501
0.000
0.000
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.020
0.040
0.049
0.000
0.000
Total Bone Surface absorbed dose (mGy)
0.109
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
211
Table F-19. One-Year-Old effective doses for Agfa CR system at 60 kVp
Male
0.152 mSv
Female
0.155 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.5
0.2
0.8
0.9
3.3
1.4
0.6
0.0
0.5
0.4
1.1
0.3
0.1
0.0
0.0
0.0
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.146
0.056
0.220
0.253
0.995
0.396
0.186
0.000
0.131
0.119
0.333
0.086
0.028
0.000
0.000
0.000
0.000
0.125
0.014
0.058
0.188
0.167
0.497
TWF
OAD*TWF
0.05
0.003
0.05
0.05
0.12
0.05
0.050
0.020
0.022
0.000
0.05
0.12
0.017
0.010
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.015
0.003
0.007
0.002
0.002
0.005
212
Table F-19. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.5
0.8
0.9
0.0
0.0
OAD
[mGy]
BMW
OAD*BMW
0.000
0.146
0.220
0.253
0.000
0.000
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.021
0.017
0.020
0.000
0.000
Total Bone Marrow absorbed dose (mGy)
0.058
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.5
0.8
0.9
0.0
0.0
OAD
[mGy]
BSW
OAD*BSW
0.000
0.433
0.653
0.751
0.000
0.000
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.050
0.064
0.074
0.000
0.000
Total Bone Surface absorbed dose (mGy)
0.188
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
213
Table F-20. One-Year-Old effective doses for Agfa CR system at 65 kVp
Male
0.217 mSv
Female
0.223 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.4
0.0
0.1
1.6
0.9
3.5
2.3
1.9
0.1
0.5
0.7
1.2
0.0
0.0
0.2
0.0
0.0
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.121
0.000
0.028
0.439
0.253
1.055
0.650
0.588
0.033
0.131
0.209
0.363
0.000
0.000
0.061
0.000
0.000
0.000
0.170
0.031
0.072
0.243
0.318
0.528
TWF
OAD*TWF
0.05
0.001
0.05
0.05
0.12
0.05
0.053
0.033
0.071
0.002
0.05
0.12
0.018
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.020
0.006
0.009
0.002
0.003
0.005
214
Table F-20. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.4
0.0
1.6
0.9
0.0
0.0
OAD
[mGy]
BMW
OAD*BMW
0.121
0.000
0.439
0.253
0.000
0.000
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.018
0.000
0.034
0.020
0.000
0.000
Total Bone Marrow absorbed dose (mGy)
0.072
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.4
0.0
1.6
0.9
0.0
0.0
OAD
[mGy]
BSW
OAD*BSW
0.360
0.000
1.305
0.751
0.000
0.000
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.042
0.000
0.128
0.074
0.000
0.000
Total Bone Surface absorbed dose (mGy)
0.243
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
215
Table F-21. One-Year-Old effective doses for Agfa CR system at 70 kVp
Male
0.233 mSv
Female
0.242 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
0.0
1.5
1.7
0.5
0.3
1.2
0.2
3.5
3.4
1.7
0.1
0.1
0.2
0.3
1.6
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.000
0.412
0.478
0.151
0.085
0.371
0.065
0.915
1.013
0.514
0.029
0.028
0.061
0.098
0.501
0.000
0.964
0.045
0.170
0.598
0.138
0.075
TWF
OAD*TWF
0.05
0.000
0.05
0.05
0.12
0.05
0.008
0.004
0.045
0.003
0.05
0.12
0.026
0.003
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.116
0.009
0.020
0.006
0.001
0.001
216
Table F-21. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.5
1.7
0.3
1.6
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.412
0.478
0.098
0.501
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.032
0.037
0.021
0.080
Total Bone Marrow absorbed dose (mGy)
0.170
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.5
1.7
0.3
1.6
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
1.223
1.418
0.290
1.487
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.120
0.139
0.064
0.275
Total Bone Surface absorbed dose (mGy)
0.598
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
217
Table F-22. One-Year-Old effective doses for Agfa CR system at 75 kVp
Male
0.297 mSv
Female
0.300 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.1
0.6
2.0
1.6
0.5
1.4
1.6
0.0
2.4
3.8
3.4
0.1
0.1
0.2
0.5
1.8
0.1
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.029
0.167
0.549
0.449
0.151
0.396
0.495
0.000
0.627
1.132
1.028
0.029
0.028
0.061
0.163
0.563
0.029
0.880
0.045
0.207
0.716
0.230
0.090
TWF
OAD*TWF
0.05
0.008
0.05
0.05
0.12
0.05
0.008
0.020
0.059
0.000
0.05
0.12
0.051
0.003
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.006
0.106
0.009
0.025
0.007
0.002
0.001
218
Table F-22. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
2.0
1.6
0.5
1.8
OAD
[mGy]
BMW
OAD*BMW
0.000
0.029
0.549
0.449
0.163
0.563
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.004
0.043
0.035
0.036
0.089
Total Bone Marrow absorbed dose (mGy)
0.207
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
2.0
1.6
0.5
1.8
OAD
[mGy]
BSW
OAD*BSW
0.000
0.087
1.631
1.335
0.483
1.673
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.010
0.160
0.131
0.106
0.310
Total Bone Surface absorbed dose (mGy)
0.716
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
219
Table F-23. One-Year-Old effective doses for Agfa CR system at 80 kVp
Male
0.297 mSv
Female
0.300 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.1
0.6
2.0
1.6
0.5
1.4
1.6
0.0
2.4
3.8
3.4
0.1
0.1
0.2
0.5
1.8
0.1
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.029
0.167
0.549
0.449
0.151
0.396
0.495
0.000
0.627
1.132
1.028
0.029
0.028
0.061
0.163
0.563
0.029
0.880
0.045
0.207
0.716
0.230
0.090
TWF
OAD*TWF
0.05
0.008
0.05
0.05
0.12
0.05
0.008
0.020
0.059
0.000
0.05
0.12
0.051
0.003
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.006
0.106
0.009
0.025
0.007
0.002
0.001
220
Table F-23. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
2.0
1.6
0.5
1.8
OAD
[mGy]
BMW
OAD*BMW
0.000
0.029
0.549
0.449
0.163
0.563
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.004
0.043
0.035
0.036
0.089
Total Bone Marrow absorbed dose (mGy)
0.207
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
2.0
1.6
0.5
1.8
OAD
[mGy]
BSW
OAD*BSW
0.000
0.087
1.631
1.335
0.483
1.673
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.010
0.160
0.131
0.106
0.310
Total Bone Surface absorbed dose (mGy)
0.716
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
221
Table F-24. One-Year-Old effective doses for Agfa CR system at 85 kVp
Male
0.465 mSv
Female
0.529 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.2
0.0
1.7
2.6
4.2
0.5
1.8
2.4
0.0
5.5
5.2
4.4
0.5
1.3
0.9
0.2
3.3
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.061
0.000
0.475
0.714
1.180
0.151
0.509
0.743
0.000
1.437
1.549
1.330
0.144
0.364
0.275
0.065
1.033
0.000
1.493
0.319
0.335
1.182
0.349
0.075
TWF
OAD*TWF
0.05
0.024
0.05
0.05
0.12
0.05
0.008
0.025
0.089
0.000
0.05
0.12
0.067
0.017
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.179
0.064
0.040
0.012
0.003
0.001
222
Table F-24. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.2
0.0
2.6
4.2
0.2
3.3
OAD
[mGy]
BMW
OAD*BMW
0.061
0.000
0.714
1.180
0.065
1.033
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.009
0.000
0.056
0.092
0.014
0.164
Total Bone Marrow absorbed dose (mGy)
0.335
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.2
0.0
2.6
4.2
0.2
3.3
OAD
[mGy]
BSW
OAD*BSW
0.180
0.000
2.121
3.504
0.193
3.067
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.021
0.000
0.208
0.343
0.042
0.567
Total Bone Surface absorbed dose (mGy)
1.182
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
223
Table F-25. One-Year-Old effective doses for Canon DR system at 50 kVp
Male
0.099 mSv
Female
0.099 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
0.0
0.3
0.6
0.0
0.0
0.2
0.0
2.1
1.4
0.8
0.1
0.0
0.0
0.0
1.9
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.000
0.082
0.169
0.000
0.000
0.062
0.000
0.549
0.417
0.242
0.029
0.000
0.000
0.000
0.595
0.000
0.483
0.000
0.114
0.400
0.023
0.000
TWF
OAD*TWF
0.05
0.000
0.05
0.05
0.12
0.05
0.000
0.000
0.007
0.000
0.05
0.12
0.012
0.003
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.058
0.000
0.014
0.004
0.000
0.000
224
Table F-25. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
0.3
0.6
0.0
1.9
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.082
0.169
0.000
0.595
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.006
0.013
0.000
0.094
Total Bone Marrow absorbed dose (mGy)
0.114
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
0.3
0.6
0.0
1.9
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
0.245
0.501
0.000
1.766
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.024
0.049
0.000
0.327
Total Bone Surface absorbed dose (mGy)
0.400
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
225
Table F-26. One-Year-Old effective doses for Canon DR system at 55 kVp
Male
0.180 mSv
Female
0.163 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
0.2
1.0
0.8
0.0
0.2
0.5
0.0
2.5
2.5
1.0
0.1
0.0
0.0
0.0
3.8
0.3
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.056
0.275
0.225
0.000
0.057
0.155
0.000
0.653
0.745
0.302
0.029
0.000
0.000
0.000
1.190
0.087
0.699
0.000
0.228
0.799
0.060
0.044
TWF
OAD*TWF
0.05
0.003
0.05
0.05
0.12
0.05
0.000
0.003
0.019
0.000
0.05
0.12
0.015
0.003
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.017
0.084
0.000
0.027
0.008
0.001
0.000
226
Table F-26. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.0
0.8
0.0
3.8
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.275
0.225
0.000
1.190
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.021
0.018
0.000
0.189
Total Bone Marrow absorbed dose (mGy)
0.228
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.0
0.8
0.0
3.8
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
0.816
0.667
0.000
3.532
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.080
0.065
0.000
0.653
Total Bone Surface absorbed dose (mGy)
0.799
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
227
Table F-27. One-Year-Old effective doses for Canon DR system at 60 kVp
Male
0.239 mSv
Female
0.248 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
0.5
1.7
1.4
0.2
0.2
0.2
0.1
4.1
4.1
1.8
0.0
0.2
0.1
0.1
5.2
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.140
0.467
0.393
0.060
0.057
0.062
0.033
1.071
1.221
0.544
0.000
0.056
0.031
0.033
1.628
0.000
1.146
0.043
0.333
1.166
0.038
0.030
TWF
OAD*TWF
0.05
0.007
0.05
0.05
0.12
0.05
0.003
0.003
0.007
0.002
0.05
0.12
0.027
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.138
0.009
0.040
0.012
0.000
0.000
228
Table F-27. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.7
1.4
0.1
5.2
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.467
0.393
0.033
1.628
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.036
0.031
0.007
0.258
Total Bone Marrow absorbed dose (mGy)
0.333
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.7
1.4
0.1
5.2
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
1.387
1.168
0.097
4.834
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.136
0.114
0.021
0.894
Total Bone Surface absorbed dose (mGy)
1.166
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
229
Table F-28. One-Year-Old effective doses for Canon DR system at 65 kVp
Male
0.230 mSv
Female
0.236 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
0.3
1.2
0.8
0.0
0.6
0.2
0.0
4.4
4.4
1.5
0.0
0.2
0.0
0.3
3.8
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.084
0.330
0.225
0.000
0.170
0.062
0.000
1.150
1.311
0.453
0.000
0.056
0.000
0.098
1.190
0.000
1.230
0.028
0.253
0.878
0.058
0.000
TWF
OAD*TWF
0.05
0.004
0.05
0.05
0.12
0.05
0.000
0.008
0.007
0.000
0.05
0.12
0.023
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.148
0.006
0.030
0.009
0.001
0.000
230
Table F-28. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.2
0.8
0.3
3.8
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.330
0.225
0.098
1.190
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.026
0.018
0.021
0.189
Total Bone Marrow absorbed dose (mGy)
0.253
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
1.2
0.8
0.3
3.8
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
0.979
0.667
0.290
3.532
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.096
0.065
0.064
0.653
Total Bone Surface absorbed dose (mGy)
0.878
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
231
Table F-29. One-Year-Old effective doses for Canon DR system at 70 kVp
Male
0.320 mSv
Female
0.326 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.2
0.0
0.6
2.4
1.8
0.9
1.2
0.9
0.0
5.0
4.5
1.3
0.0
0.0
0.2
0.0
6.6
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.061
0.000
0.167
0.659
0.506
0.271
0.339
0.279
0.000
1.307
1.340
0.393
0.000
0.000
0.061
0.000
2.066
0.000
1.323
0.031
0.428
1.495
0.154
0.136
TWF
OAD*TWF
0.05
0.008
0.05
0.05
0.12
0.05
0.014
0.017
0.033
0.000
0.05
0.12
0.020
0.000
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.159
0.006
0.051
0.015
0.002
0.001
232
Table F-29. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.2
0.0
2.4
1.8
0.0
6.6
OAD
[mGy]
BMW
OAD*BMW
0.061
0.000
0.659
0.506
0.000
2.066
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.009
0.000
0.051
0.039
0.000
0.328
Total Bone Marrow absorbed dose (mGy)
0.428
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.2
0.0
2.4
1.8
0.0
6.6
OAD
[mGy]
BSW
OAD*BSW
0.180
0.000
1.958
1.502
0.000
6.135
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.021
0.000
0.192
0.147
0.000
1.135
Total Bone Surface absorbed dose (mGy)
1.495
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
233
Table F-30. One-Year-Old effective doses for Canon DR system at 75 kVp
Male
0.407 mSv
Female
0.401 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
1.2
4.1
1.5
0.0
1.3
1.8
0.0
4.8
4.6
2.9
0.5
0.2
0.0
0.5
6.2
0.2
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.335
1.126
0.421
0.000
0.368
0.557
0.000
1.254
1.370
0.877
0.144
0.056
0.000
0.163
1.941
0.058
1.312
0.028
0.464
1.622
0.267
0.029
TWF
OAD*TWF
0.05
0.017
0.05
0.05
0.12
0.05
0.000
0.018
0.067
0.000
0.05
0.12
0.044
0.017
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.012
0.157
0.006
0.056
0.016
0.003
0.000
234
Table F-30. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
4.1
1.5
0.5
6.2
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
1.126
0.421
0.163
1.941
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.088
0.033
0.036
0.308
Total Bone Marrow absorbed dose (mGy)
0.464
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
4.1
1.5
0.5
6.2
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
3.344
1.251
0.483
5.763
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.328
0.123
0.106
1.066
Total Bone Surface absorbed dose (mGy)
1.622
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
235
Table F-31. One-Year-Old effective doses for Canon DR system at 80 kVp
Male
0.314 mSv
Female
0.317 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.0
1.3
2.0
1.7
0.0
1.5
0.6
0.3
4.8
3.1
1.0
0.5
0.3
0.2
0.5
6.8
0.2
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.000
0.363
0.549
0.478
0.000
0.424
0.186
0.098
1.254
0.923
0.302
0.144
0.084
0.061
0.163
2.129
0.058
1.089
0.073
0.454
1.574
0.213
0.029
TWF
OAD*TWF
0.05
0.018
0.05
0.05
0.12
0.05
0.000
0.021
0.022
0.005
0.05
0.12
0.015
0.017
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.012
0.131
0.015
0.054
0.016
0.002
0.000
236
Table F-31. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
2.0
1.7
0.5
6.8
OAD
[mGy]
BMW
OAD*BMW
0.000
0.000
0.549
0.478
0.163
2.129
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.000
0.043
0.037
0.036
0.338
Total Bone Marrow absorbed dose (mGy)
0.454
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.0
2.0
1.7
0.5
6.8
OAD
[mGy]
BSW
OAD*BSW
0.000
0.000
1.631
1.418
0.483
6.321
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.000
0.160
0.139
0.106
1.169
Total Bone Surface absorbed dose (mGy)
1.574
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
237
Table F-32. One-Year-Old effective doses for Canon DR system at 85 kVp
Male
0.404 mSv
Female
0.430 mSv
Organ Sites
Face Spine
Head Spine
Thyroid
Rt. Arm
Lt. Arm
Breast
Liver
Stomach
Bladder
Rt. Lung
Lt. Lung
Esophagus
Colon
Rt. Ovary
Lt. Ovary
Pelvis
Spine Middle
Testes
Average Lung
Average Ovary
Bone Marrow
Bone Surface
Remainder
Surface
MOSFET
CF
[mV]
[mR/mV]
0.0
0.1
0.9
1.8
2.2
0.0
1.7
1.4
0.1
5.8
5.2
2.8
0.8
0.5
0.4
0.0
5.5
0.0
29.29
30.46
31.82
32.34
31.62
29.47
31.42
28.70
27.21
33.99
29.82
29.38
30.84
31.72
29.12
27.29
28.38
30.46
DCF
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
1.014
OAD
[mGy]
0.000
0.029
0.251
0.494
0.618
0.000
0.481
0.433
0.033
1.516
1.549
0.847
0.230
0.140
0.122
0.000
1.722
0.000
1.532
0.131
0.364
1.280
0.294
0.000
TWF
OAD*TWF
0.05
0.013
0.05
0.05
0.12
0.05
0.000
0.024
0.052
0.002
0.05
0.12
0.042
0.028
0.2
0.12
0.2
0.12
0.01
0.01
0.01
0.000
0.184
0.026
0.044
0.013
0.003
0.000
238
Table F-32. Continued
Bone Marrow Absorbed Dose Calculation
Bone marrow MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
1.8
2.2
0.0
5.5
OAD
[mGy]
BMW
OAD*BMW
0.000
0.029
0.494
0.618
0.000
1.722
0.1470
0.1470
0.0779
0.0779
0.2191
0.1588
0.000
0.004
0.039
0.048
0.000
0.273
Total Bone Marrow absorbed dose (mGy)
0.364
29.29
30.46
32.34
31.62
27.29
28.38
1.014
1.014
1.014
1.014
1.014
1.014
Bone Surface Absorbed Dose Calcalution
Bone surface MOSFET
CF
sites
[mV]
[mR/mV] DCF
Face Spine
Head Spine
Rt. Arm
Lt. Arm
Pelvis
Spine Middle
0.0
0.1
1.8
2.2
0.0
5.5
OAD
[mGy]
BSW
OAD*BSW
0.000
0.087
1.468
1.835
0.000
5.112
0.1160
0.1160
0.0980
0.0980
0.2190
0.1850
0.000
0.010
0.144
0.180
0.000
0.946
Total Bone Surface absorbed dose (mGy)
1.280
29.2941
30.4587
32.3377
31.619
27.2877
28.3761
3.011
3.011
3.011
3.011
3.011
3.011
APPENDIX G
PROBLEMS WITH CT PHANTOMS
For CT, it was proposed that the MTF and NPS be calculated using the Catphan CT
phantom. To image the items in the phantom, CT slices should be perpendicular to the
axis of the phantom as displayed in Figure G-1(A). One slice of the Catphan is the
CTP446 high resolution module with 21 line pairs groups which is displayed in Figure G1(B).
Metal
Fixture
Axis
Figure G-1. Proper orientation of a CT Phantom (A) The proper orientation of the
Catphan. (B) Image of the CTP446 high resolution module.
The GE Lightspeed QX/I has two helical mode, high quality and high speed. High
quality refers to a pitch of 3:1 and high speed refers to a pitch of 6:1. The Catphan was
not adequate for the high speed scanning. Figure G-2 compares the CTP446 high
resolution module at (A) high quality and (B) high speed. The high speed image shows
streaks.
239
240
Axis
Figure G-2. The CTP446 high resolution module (A) imaged with high quality 3:1 pitch
and (B) imaged with high speed 6:1 pitch.
Figure G-3. Orientation of a CT phantom for planar reconstructed images (A) The
Catphan in a 90 degree orientation. (B) Reconstructed image of the CTP446
high resolution module.
To produce reconstructed images, the phantom was turned 90 degrees and scanned
parallel to the phantom axis as shown in Figure G-3 (A). The image of the CTP446 high
resolution module was reconstructed and is shown in Figure G-3(B). Because the
phantom was turned 90 degrees and scanned, the entire phantom was scanned including
the metal fixtures on the end. The metal shows up as artifacts on the reconstructed image.
Also contained in the phantom is a tungsten carbide bead. This bead shows in the helical
241
images in Figure G-1 and G-2 but not in Figure G-3. The line pairs in the reconstructed
images are not as distinctly separated as in the helical images. Line pair separation is
necessary for the Droege and Morin (1982) method of determining the MTF with the line
pair phantom. The resolution of the phantom was not adequate for determining the MTF
of the reconstructed image.
To determine the NPS, flat field images are necessary. There is a part of the
Catphan with no embedded objects as shown in Figure G-4 (A). The artifacts in the
reconstruct image are caused by the metal in the Catphan. The artifacts make it difficult
to obtain a large flat field area necessary for the NPS calculation.
Figure G-4. Planar reconstructed images (A) Catphan flat field image and (B)
reconstructed flat field image.
The CT phantom available was not adequate for MTF and NPS measurements of
reconstructed images. This phantom was constructed to be imaged with CT slices
perpendicular to the phantom axis. A new phantom is needed to measure image quality in
other planes.
LIST OF REFERENCES
Antonuk LE, Yorkston J, Huang WD, Siewerdsen JH, Boudry JM, Elmohri Y, Marx MV,
“A Real-Time, Flat-Panel, Amorphous-Silicon, Digital X-Ray Imager”,
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BIOGRAPHICAL SKETCH
Kennita A. Johnson was born March 22, 1974 in Washington, D.C. to Kenneth and
Barbara Johnson. There she attended Eleanor Roosevelt High School, where she took
part in the science and technology program. There she excelled in science and won first
place in the school science fair and second place in the tri-county science fair in the
chemistry division with her project on chemiluminescent materials. From there she
attended University of Maryland Baltimore County (UMBC) where she received her
Bachelors of Science degree in physics with a minor in sociology. While attending
UMBC, she held an internship at NASA Goddard Space Flight Center in the materials
branch where she tested electrostatic materials and learned to program in LabVIEW. Her
knowledge of LabVIEW lead to an undergraduate research project in a nonlinear optics
lab where she tested materials that would be used in optical storage devices.
For her graduate studies, she decided to switch gears in order to study medical
physics at the University of Florida. While getting her Masters of Science degree in
medical physics from the Department of Nuclear and Radiological Engineering, she
developed a passion for politics and public service. This passion led her to presidencies
of the student chapter of the Health Physics Society,and the Benton Engineering Council,
as well as 3 terms as a Student Governement Senator. All of her accomplishments
culminated in being named to the University of Florida Hall of Fame. After finishing her
Masters degree, she decided to continue her education and recieved a Doctor of
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Philosophy degree from the Department of Biomedical Engineering with an emphasis on
medical image formation and processing in the summer of 2003.