Download Heart

Imaging Procedure 1
Final Revision
Main Factors Affecting Recorded
Image Detail
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kVp & mAs
Motion
Object Unsharpness
Focal Spot Size
SID (Source to Image Distance)
OID (Object to Image Distance)
Material Unsharpness
Size Distortion & OID
• If source is kept constant, OID will affect
magnification
• As OID , magnification 
• The farther the object is from the film, the
more magnification
Image Distortion
• When the part to be imaged – does not lay
parallel with the IR (cassette)
• If the Central Ray is not perpendicular to the
part
FOCAL SPOT ANGLE
SMALLER ANGLE – SMALLER BEAM AT
PATIENT
Film Speed / Crystal size
• Larger crystals or Thicker crystal layer
Faster response= less detail, and
less exposure (chest x-ray)
• Finer crystals / thinner crystal layer
=Slower response, greater detail,
more exposure (extremity)
Axial Skelton- 80 bones
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Cranium-8
Facial-14
Hyoid-1
Auditory ossicles-6
Cervical vert.-7
Thoracic vert.-12
Lumbar vert.-5
Sacrum-1
Coccyx-1
Sternum-1
Ribs-24
Total-80
Anatomic Position
• Upright, arms adducted,
palms forward, head and
feet directed straight ahead
• Viewing Radiographs:
Display x-rays so that the
patient is facing the viewer
in anatomic position
R
Body Surfaces and Parts
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Posterior or dorsal
Anterior or ventral
Plantar- sole of foot
Dorsal- top of anterior surface of foot, back or
posterior aspect of hand
• Palmar- palm of hand or the anterior/ventral
surface
Image Markers and Patient ID
• All films should have two markers:
– Patient ID and date
– Anatomic side markers
Most Useful Applications for Plain XRays
• Chest
• Musculoskeletal
• Abdomen: limited usefulness
Main Uses of Fluoroscopy
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Gastrointestinal Imaging
Genitourinary Imaging
Angiography
Other
– Intraoperative
– Foreign body removal
– Musculoskeletal
Modified Barium Swallow
Upper GI Exam
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Evaluates esophagus, stomach and duodenum
Double or Single Contrast
Can be combined with small bowel series
Largely replaced by endoscopy and crosssectional imaging
• Fairly insensitive
Cystogram
• Usually in adult patients
• Looking for tear or intraluminal mass
• Catheter placed and bladder filled with
contrast to capacity: usually 300-500 ml.
• Spot films obtained when full
• Post void film: usually overhead
Cystogram
Cystogram with Intraperitoneal Rupture
Techniques - Projection
•P-A (relation of x-ray beam to patient)
Techniques - Projection (continued)
• Decubitus
Rotation
(continued)
Heart
Right border: Edge of (r) Atrium
3. Left border: (l) Ventricle + Atrium
4. Posterior border: Reft Ventricle
5. Anterior border: Right Ventricle
Heart (continued)
Heart
•Size:
Heart
•Size of heart
•Size of individual
chambers of heart
•Size of pulmonary
vessels
•Evidence of stents, clips,
wires and valves
•Outline of aorta and IVC
and SVC
Procedure
• Apply proper compression to produce uniform
breast thickness
– Essential to high-quality mammograms
• Place ID markers
Routine mammography projections
Craniocaudal (CC)
Mediolateral oblique
(MLO)
CT Protocolling
• Variables
– Plain or contrast enhanced
– Slice positioning
– Slice thickness
– Slice orientation
– Slice spacing and overlap
– Timing of imaging and contrast administration
– Reconstruction algorhithm
– Radiation dosimetry
CT Terminology
• Window Width
– Number of Hounsfield units from black to white
• Level or Center
– Hounsfield unit approximating mid-gray
CT Terminology
Clinical Applications
• Multisection CT aquires changes in the
planning and staging of patient examinations.
The scanning time is reduced for most
examinations, requiring adjustments in the
administration of intravenous contrast
material. The amount of contrast material can
be reduced, and different vascular phases can
be better visualized. Thin-section scanning
allows production of high-quality MPR images
• Couinaud’s hepatic segments divide the liver into
eight segments . The hepatic veins are the
longitudinal boundaries . The transverse plane is
defined by the right and left portal pedicles .
Sonographic Evaluation of the Liver
• Evaluation of the hepatic structure is one of
the most important procedures in sonography
for many reasons. The normal , basiclly
homogenerous parenchyma of the liver
allows imaging of the neighboring anatomic
structures in the upper abdomen.
• The appropriate transducer depends on
the patient’s body habitus and size
• The average adult abdomen usually
requires a 3.5MHz
Sagittal image of gallbladder
• Doppler ultrasound is used primarily to identify and evaluate blood flow in vessels
• velocity and waveform information can be used to evaluate stenoses, resistance
and vessel patency
Doppler Frequency Shift (fD)
f
f0
doppler frequency shift (fD) = change in frequency
= (f0 - f)
(RBC)
where f0 is the original frequency and f is the frequency of the returning echo
(from RBC)
• maximum shift is obtained when  = 0°
• minimum shift is obtained when  = 90° (recall, imaging of strongest echoes)
• the shift is comparatively small and typically is between 0 - 15 kHz (audible sound)
• the shift is positive when the RBC is moving towards the transducer and is negative
when the RBC is moving away from the transducer
Color Flow Doppler
• Color Doppler is a hybrid that combines anatomicn obtained using
B-mode system with flow information obtained using pulsed Doppler analysis
• colors (blue and red) are assigned dependent on motion (toward or away) from the
transducer
• turbulence (i.e.: variations in flow direction) can vary between green and yellow
• the depth of each color varies with the velocity of flow, stationary tissues appear gray
• information is provided over a large area and superimposed on a gray scale image
• color Doppler can detect flow in vessels too small to see by imaging alone
• spectral analysis may also be obtained using commercial color Doppler systems
• modern instruments incorporate both color Doppler and spectral Doppler
• Oxygen, hydrogen, carbon, nitrogen elements
constitute 96 % of human body mass.
• Oxygen is 65 % of body mass; carbon is 18.5
%, hydrogen 9.5 %, nitrogen 3.2 %.
• Let us ignore all elements but Hydrogen.
T1-weighted contrast
T2-weighted contrast
Tissue Appearance
WT
FAT
H2O
MUSC
LIG
BONE
T1
B
D
I
D
D
Proton I
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I
D
D
T2
B
I
D
D
Density
I
Good Luck