Terminology and Visual Perceptions

Question 1

What are the 5 radio-opacities

Answer 1

Air
Fat
Fluid (soft tissue)
Mineral (bone)
Metal

Question 2

Why are the bones of one thing less radio-opaque than another?

Answer 2

Due to the fatness and density and atomic number.

Question 3

Which leg is which according to size?

Answer 3

The leg closest to the imaging plate is bigger.

Question 4

What is positive summation?

Answer 4

When two things of the same opacity are on top of each other causing one to become more opaque than the other.

Question 5

What is negative summation?

Answer 5

When two things of similar radiolucency are superimposed causing them to appear darker than they are.

Question 6

What is border effacement?

Answer 6

Also known as negative silhouette, is the inability to marginalise an organ as something of similar opacity is sitting next to it.

Question 7

What is positive silhouette?

Answer 7

The silhouette of adjacent objects of the same opacity is enhanced when surrounded by different tissue opacity. As seen in the left image.

Question 8

What is the correct image orientation?

Answer 8

Rostral and lateral views have the animal facing the left.
The label is always put on the lateral side.

Question 9

What is the approach to assessing radiographs?

Answer 9

1. Identify the subject
   * signalmen
   * clinical history
   * date and type of study
   * which anatomical part
   * which projections
   * Any previous studies.
2. Radiographic exam techniques
   * nature and type of drugs, sedatives, anaesthesia, contrast or pharmaceuticals
   * Route of administration
   * any adverse effects
3. Assess the radiographic quality
   P - position
   L - label
   A - artifact
   C - collimation and cantering
   E - exposure
   and does it meet ALARA standards
4. Radiological findings
   Is it of diagnostic quality
   Descriptive phase using roentgen signs
5. Interpretation of findings
   - Radiological diagnosis
   - List of differential diagnosis in order of likely hood.
6. Further imaging studies

Question 10

What are the roentgen signs?

Answer 10

Size
Shape
Location/position/alignment
Margination
Number
Opacity
Function

Question 11

What are the steps to report writing?

Answer 11

1. Identify case
2. Identify all views taken
3. Evaluate quality of images
4. Describe all radiographic abnormalities
5. Conclusion/diagnosis
6. Consider other imaging

Question 12

What are the different errors of interpretation?

Answer 12

Bias errors - expecting to find something
Searching errors - not being systematic
Recognition errors - abnormalities recognised but given too much weight or not taking into account and misinterpreting
Decision making errors - abnormalities assumed to be important.
Egocentric errors - overestimating your personal grasp of the truth