1. Radiographic Positioning: an overview
RVT: Chapter 17

2. Learning Objectives
Understand the proper anatomical positioning terminology used in veterinary radiography
Understand common rules for radiographic positioning
Describe patient preparation and positioning aids
Understand the normal required radiographic views
List positioning guidelines

3. Rules of Positioning
The view that the veterinarian requests will determine the direction that the central beam will enter and exit the body.
This is why most radiograph views have two names
The first direction is the anatomical part the beam enters
This anatomy is closest to the __________ __________
The second is the direction the radiation exits the patient
This piece of anatomy is closest to the __________ ____________
Example: Ventrodorsal view
Example: Dorsoventral view
*Combining 2 terms = usually use “o” as combining vowel

4. Abbreviations
Abbreviated terms are often used to indicate the direction of the x-ray beam as well
First letter states where the x-ray beam enters the body, the second designates where it exits.
V/D – enters ventrally and exits dorsally
CrCd – enters cranial aspect of front or back leg above carpus/tarsus and exits caudal aspect

5. Terminology Recumbent:
The animal is lying down when the radiograph is made.
Most radiographs of the dog and cat are in a recumbent position.
This position should be presumed unless otherwise stated on the radiograph.

6. Major Anatomical Planes
Mediolateral
Dorsopalmar/dorsoplantar
Cranial/Caudal

7. Limb Terminology Caudal (Cd): Cranial (Cr):
Towards the tail from any given point
Aspects of limbs _______ the carpal and tarsal joints that face the rear of the animal
Cranial (Cr):
Towards the head
Aspects of the limb _____
the carpal and tarsal joints
that face toward the head
CrCd Femur

8. Limb Terminology Dorsal (D):
Upper aspect of the head, neck, trunk, and tail
Toward the spine of the animal
Aspects of the legs distal to and including the carpus and tarsus joints that face “up” when standing.
Dorsal Recumbency

9. Dorsal Aspect: Metacarpals

10. Limb Terminology Palmar (Pa):
DPa L Foot
Palmar (Pa):
Used instead of caudal when describing the __________ from the carpal joint distally
Plantar (Pl):
Used instead of caudal when describing the ____________ from the tarsal joint distally

11. Positional Terminology
Ventral:
Lower aspect of the head, neck, trunk, and tail
Also: towards the abdomen of the animal; towards the ground when standing
Ventral

12. Positional Terminology
Lateral (L):
From one side to the other
Directional marker indicates side _________ to cassette
R Lateral Thoracolumbar

13. Directional Terminology
Mediolateral (ML):
X-ray beam enters through medial aspect and exits on the lateral side
Used mostly for limbs
ML Humerus

14. Directional Terminology
Lateromedial (LM)
Beam enters the lateral aspect of the limb
Beam exits the medial aspect

15. Positional Terminology
Distal (Di)- away from the point of origin of a structure
Proximal (Pr)- towards the point of origin of a structure

16. Positional Terminology
Rostral:
Parts of the head positioned toward the _______

17. Terminology Oblique (O):
Central ray passes obliquely through patient (not parallel to one of the 3 major planes)
Patient is rotated slightly
The angulation varies
Anything other than parallel or perpendicular
Why is this necessary?
Naming- hyphen usually separates entry point from exit point
Ex: DPr-PaDi

18. Oblique Views

19. Positions?

20. Basic Criteria of Positioning
Refrain from overt physical restraint
Primary goal is to produce a good quality radiograph of the area being examined
Factors to consider:
Welfare of the patient
Restraint and immobilization of the patient
Make this the last thing you do
Condition to the rotation of the anode
Minimal trauma to the area of interest
Lowest risk of radiation exposure for personnel

21. Radiographic Restraint

22. Patient Factors Always consider your patient…
Radiography can be scary
Noises & confusion can be frightening
The animal may be in pain
“Less is more” with cats
Patience is a virtue... May require sedation or general anesthesia
Always remember your client…
This is someone’s baby, and it could be yours someday

23. Patient Preparation Clean & dry hair coat
Remove splints, bandages*, collars, leashes, etc.
Chemical restraint is preferred but not always allowed
No matter how well behaved and calm an animal seems, always expect the worst when you expose!

24. Positioning Devices
Positioning devices should not be placed directly above or below area of interest – not completely radiolucent

25. Required Views Radiograph is a 2-D picture of a 3-D structure
Norm: two views at right angles to one another
Helps to visualize structures completely
Area of interest is ________ to image receptor
Minimizes distortion and magnification
Comparison of two structures
To compare to other area to see if there are any pathological changes
Sometimes veterinarians want the affected AND healthy limb

26. Splitting the Cassette
Used for taking more than 1 image on a single film
Great for taking comparison views
Use lead sheets or lead gloves (usually) to:
Cover “non-used” portions of cassette to take first view, then systematically uncover for subsequent and cover previously imaged sections
Not practical when using grid
Split as many times as necessary
Tip: The 2 views need to be in the same direction!

27. Splitting the Cassette

28. Collimation, Collimation, Collimation
Very important!
Decreases scatter and increases contrast.

29. Positioning Guidelines
Center primary beam over area of interest
Use caliper to measure thickest part
Thickest part of anatomy towards cathode

30. Positional Marker Placement
Lateral body rads: place cranial and ventral
DP and CrCd limb views: place marker towards lateral aspect of leg
ML/LM limb views: place marker towards cranial aspect of leg
These are general recommendations for consistency…not the end of the world if this is missed.

31. Radiographic Checklist
Image labeled & legible?
Positional markers present?
Good contrast & density?
Anatomy roperly centered on film?
Properly collimated?
Correct positioning without rotation?
Evidence of human exposure?
Film properly developed?
Artifacts present?
Image diagnostic? Or repeat needed?