Principles of interpretation Flashcards
Radiographic opacities
-more x ray photons reach detector= darker (radiolucent)
-less x ray photons reach detector= brighter (radioopaque)
Hanging protocol
Viewing radiographs in same orientation trains the brain to get pattern
-lateral with head facing viewers left
-VD and DV, head up at top of screen; patients right on viewers left
-DP/CC images= limbs oriented with proximal end of extremity pointing up/top of screen
What should you take into account when viewing 3D information as a 2D image?
-magnification
-distortion
-superimposition
Magnification
Enlargement of structure in image relative to actual size
-based on increased distance between object and the plate
-as distance increased, resolution decreases
Distortion
Uneven mag that occurs when the plane of the object and the plate are not parallel
-can result in misrepresentation of the true shape or position of the object
Superimposition
The overlaying of one object on another
-need to have orthogonal views to determine
Roentgen signs
How we describe radiographic abnormalities
-number
-size
-shape
-margination
-opacity
-location
Number
A change in the expected number of structures
eg. solitary/focal vs multiple/ multifocal
Size
Increase or decrease in size of structure
Shape
Change in shape of a structure from what is expected
Margination
Change in the expected outline of a structure
eg. well defined vs. ill defined
Opacity
A change in the expected location of structures
Radiographic interpretation paradigm
- ensure accurate position and proper radiographic technique
- examine radiographs in systemic way
*more of an art than science - describe abnormalities you can see= Roentgen signs
- Make differential diagnosis list
What clinical information must be used along with radiographs?
-patient signalment (species, breed, age, sex, reproductive status)
-history
-physical exam
-lab work findings
Common radiographic interpretation errors
-perception error= untrained eyes unable to see normal vs abnormal. Fix= practice
-satisfaction of search error= looking for a specific lesion or disease and ignoring other information. Fix by using systematic approach
-Analytical error= incorrect analysis of findings based on case exposure and poor understanding of pathophysiology
-bias= expecting to find something and then making radiographic signs fit that expectation. Fix this by reading images without history first
