Principles of Interpretation

Question 1

Image formation

Answer 1

Black- all x rays hit the receiver (digital plate or cassette and film)
white- all x rays have been absorbed by patient
Various shades of gray- some x rays hit the receiver some absorbed by the patient

Question 2

Radiopacity

Answer 2

Relative inability of structures to be penetrated by xrays

Metals of high atomic number prevent xray penetration

Question 3

Radiolucency

Answer 3

Describes substances that are of low atomic number that allow xrays to penetrate them leaving darkened images on the radiograph
Air is most radiolucent

Question 4

Contrast resolution

Answer 4

Ability to tell the differences between adjacent structures

Radiographs are limited, CT and MRI most sensitive

Question 5

Radiographic geometry

Answer 5

Representing 3D on 2D leads to some distortion and magnification of the image
Familiar parts look unfamiliar
loss of perception of depth
Superimposition

Question 6

Magnification

Answer 6

Structure in image larger than actual size
As the distance between object and plate increases, object looks bigger and detail decreases
Areas of interest should be placed as close to plate as possible
EXCEPT small animal thorax, lesions in the non-dependent lung are best seen than the dependent lung

Question 7

Dependent

Answer 7

On table- closer to plate

Question 8

Depth perception

Answer 8

Need at least 2 orthogonal views of any structure to overcome loss of depth perception

Question 9

Superimposition

Answer 9

Images of structures seen overlapping each other can be interpreted as a separate structure
Summation- overlapping of structures, the resulting opacity does not represent a separate structure

Question 10

Border effacement/silhouette sign

Answer 10

Occurs when structures of similar opacity are in contact with each other and their borders can no longer be seen
(coronary arteries are not seen on radiographs)
However if structures of similar opacity are separated by a differing opacity their borders will be well defined

Question 11

Naming views

Answer 11

Named for the direction of the primary beam
Name starts with the point of entry and followed by point of exit
Ventrodorsal= dorsal recumbency beam enters ventral portion and exits dorsum

Question 12

Viewing radiographs

Answer 12

Lateral- cranial portion pointing left
Ventrodorsal/dorsoventral- head up left on viewers right
limbs- proximal up , cranial to left

Question 13

Radiographic interpretation

Answer 13

Signalment
History
Physical findings
may lead to other tests
accurate positioning and proper radiographic technique
should evaluate in quite location
image report- helps to describe any abnormalities and in the overall evaluation of the image

Question 14

Roentgen signs

Answer 14

Change in: size, shape, location, numbers, margination/border of structure, expected opacity of structure,

Question 15

DAMNITV

Answer 15

degenerative
anomalous
metabolic
neoplastic
infection, inflammatory, immune
trauma
vasculae

Question 16

Looking at a radiographic stufy

Answer 16

Exposure setting
patient positioing
look at structures, determine whether normal or abnormla
Remember to look at all the structures in the radiograph not just the ones associated with the reported clinical signs