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Density Labels: X-ray & Ultrasound
While Mass Spectroscopy is not covered
in our texts, other mass/density
dependent technologies including X-ray
Spectroscopy, Gamma Spectroscopy, &
Ultrasound Analysis are covered in Guy &
ffytche, An Introduction to The Principles
of Medical Imaging, Imperial College
Press, 2000, Chapters 4,5 & 7.
Other coverage is also found in Shung,
Chapters 1, X-ray, & 2, Ultrasound, in
Shung, Smith, Tsui, Principles of Medical
Imaging, Academic Press, 1992.
X- ray
Here a collimated beam of X-rays generated by a
radioactive or electronically excited filament source
is used to probe the density of objects placed
between the source & a detector (film, fluorescent
screen, storage phosphor, photodiode array).
Absorbance of the x-ray energy by the medium or
reflection or refraction of the beam will alter the
exposure of the detector. Distance of the detector
from the source will limit detector exposure, so object
thickness decreases beam strength automatically.
Internal reflections “fuzz” the sample image. Imaging
improvements help correct such abberation.
Reconstruction of images requires Fourier &
triangulation deconvolution as in MRI.
Heavy atoms yield higher X- ray absorbances than
light atoms so they can be used as opaque markers or
“contrast agents.”
Basic X - Ray
Schematics
www.computingcases.org/.../
Software_Design.html
http://rst.gsfc.nasa.go
v/Intro/Part2_26b.html
X-ray Basics & Theory
Principles of Radiography:
www.kodak.com/.../kpro/radiography/ W37_03.shtml
http://learntech.uwe.ac.uk/radiography/RScience/imaging
_principles_d/diagimage1.htm
www.thejcdp.com/.../williamson/ 03williamson.htm
Atomic physics principles:
www.hmi.de/people/schiwietz/ links.html
History of radiology:
www.xray.hmc.psu.edu/ rci/ss9/ss9_15.html
Digital X-ray background:
www.gemedicalsystems.com/.../ dig_xray_intro.html
Medical Imaging:
www.csmt.ewu.edu/csmt/phys/ bhouser/medim.htm
www.qdixray.com.au/ GeneralXray.htm
astro.ocis.temple.edu/.../ PrinRad1.htm
X-ray crystallographic technology:
www.chemistry.ucsc.edu/.../ chem200a/schedule.html
sharp-world.com/corporate/
news/030930-2.html
Validation Issues
Calibration for accuracy, sensitivity, precision &
specificity requires examination of phantoms,
objects, or crystals with known composition,
architecture & structure. Imaging may be limited
by the amount of time a subject can be exposed
without doing damage by exposing them/it to xray bombardment. Most modern techniques have
attempted to minimize exposures by maximizing
the information collected in a given time. Flat
panel electronics & digitizing approaches have
helped as have the use of highly dense contrast
agents. But computer analysis of image data
combined with Fourier transform techniques have
greatly speeded the process & made it safer. It is
now possible to do computed tomographic
imaging to high resolutions.
www.aps.anl.gov/ald/grafgal2/ digital/reserch.htm
X-ray Contrast Media:
http://www.xray2000.f9.co.uk/Site3/contrast_media/contrast
_media_introduction.htm
www.amershamhealth.com/medcyclopaedia/ Volume%...
www.ferringfertility.com/.../ uterine.htm
More Advanced Treatments of X-ray
Computed Tomography:
rst.gsfc.nasa.gov/Intro/ Part2_26c.html
Radiology & Ultrasonography links:
www.nyerrn.com/ x/xray.htm
Ultrasound
This method uses piezoelectric transducers to
produce ultrasonic pulses that reflect & refract
off structures in the beam path. The amount of
wave energy absorption, the reflection angles,
& the distance from the transducer to the tissue
& back to the probe determine the amount &
location of the energy delivered back to the
probe. The perceived energy & direction is
delivered to the instrument electronics &
displayed as an image. Soft tissues with
contrasting contents of water & fat are well
imaged by this technique.
Contrast agents for ultrasound incorporate
small bubbles that introduce air (gas) into the
imaged system.
Ultrasound Basics & Theory
Ultrasound Basics & Theory:
http://www.drgdiaz.com/intro.shtml
www.cyberphysics.pwp.blueyonder.co.uk/ topics/...
www.stfx.ca/.../teachersworkshops/ sld038.htm
Ultrasound in obstetrics:
www.ob-ultrasound.net/
Ultrasonography in ophthalmology
www.jhu.edu/wctb/coms/ patient/echo/echo.htm
Carotid Artery Plaque and 3D Ultrasound
Ulf Schminke, MD; Christof Kessler, MD;
Lillian Motsch, MD; Lutz Hilker, MD
Neurosonology Lab, Dept. of Neurology, Ernst Moritz Arndt
University Greifswald, Greifswald, Germany
More Advanced Treatments of Ultrasound
A simple quiz:
mark.asci.ncsu.edu/.../rtu/ rtuquiz/rtuquizc.htm
3D Reconstruction & validation:
www.fac.org.ar/.../stroke/ schminke/sld004.htm
Ultrasonography of the thyroid:
http://www.thyroidmanager.org/
FunctionTests/ultra-frame.htm
Ultrasound contrast agents:
www.ultrasonic.meng.ucl.ac.uk/ mbubble.html
Harmonic imaging:
www.medison.com/english/ pd/pd_07a.asp