1. General Principles of Positioning Chapter 12

2. Terminology Caudal: Parts of the head, neck and trunk positioned towards the tail from any given point. Also aspect of limbs above the carpal and tarsal joints that face the rear of the animal. Caudal: Parts of the head, neck and trunk positioned towards the tail from any given point. Also aspect of limbs above the carpal and tarsal joints that face the rear of the animal. Cranial- Describes parts of the neck, trunk, and tail positioned toward the head from any given point. Cranial also describes those aspects of the limb above the carpal and tarsal joints that face toward the head. Cranial- Describes parts of the neck, trunk, and tail positioned toward the head from any given point. Cranial also describes those aspects of the limb above the carpal and tarsal joints that face toward the head.

3. Terminology, cont. Distal- Farther away from the point of origin of a structure. Distal- Farther away from the point of origin of a structure. Dorsal- Upper aspect of the head, neck, trunk, and tail. The term also means toward the upper aspect of the animal. Dorsal also describes the aspects of the legs from the carpus and tarsus joints distally that face toward the head. Dorsal- Upper aspect of the head, neck, trunk, and tail. The term also means toward the upper aspect of the animal. Dorsal also describes the aspects of the legs from the carpus and tarsus joints distally that face toward the head. Lateral- the x-ray beam enters through either the left or right side of the body and emerges on the opposite side, where the cassette is positioned. Lateral- the x-ray beam enters through either the left or right side of the body and emerges on the opposite side, where the cassette is positioned.

4. Terminology, cont Mediolateral- the x-ray beam enters a limb through the medial side and exits on the lateral side. Most lateral radiographs of the limbs are taken in lateromedial projection in large animal radiography. Mediolateral- the x-ray beam enters a limb through the medial side and exits on the lateral side. Most lateral radiographs of the limbs are taken in lateromedial projection in large animal radiography. Palmar- Used instead of caudal when describing the forelimb from the carpal joint distally. Palmar- Used instead of caudal when describing the forelimb from the carpal joint distally. Plantar- Used instead of caudal when describing the hindlimb from the tarsal joint distally. Plantar- Used instead of caudal when describing the hindlimb from the tarsal joint distally.

5. And yet more Terminology Proximal- Nearer to the point of origin of a structure. Proximal- Nearer to the point of origin of a structure. Recumbent- The animal is lying down when the radiograph is made. Most radiographs of the dog and cat are made with the animal in the recumbent position, and this position should be presumed unless otherwise stated on the radiograph. Recumbent- The animal is lying down when the radiograph is made. Most radiographs of the dog and cat are made with the animal in the recumbent position, and this position should be presumed unless otherwise stated on the radiograph.

6. Almost Done Rostral- parts of the head positioned toward the nares from any given point on the head. Rostral- parts of the head positioned toward the nares from any given point on the head. Superior and Inferior- Used to describe the upper and lower dental arcades, respectively. Superior and Inferior- Used to describe the upper and lower dental arcades, respectively. Ventral- Lower aspect of the head, neck, trunk, and tail. The term also means toward the lower aspect of the animal. Ventral- Lower aspect of the head, neck, trunk, and tail. The term also means toward the lower aspect of the animal.

8. Abbreviations Left (L) Left (L) Right (R) Right (R) Dorsal (D) Dorsal (D) Medial (M) Medial (M) Lateral (L) Lateral (L) Cranial (Cr) Cranial (Cr) Rostral (R) Rostral (R) Caudal (Cd) Caudal (Cd) Palmar (Pa) Palmar (Pa) Oblique (O) Oblique (O) Plantar (Pl) Plantar (Pl)

9. Abbreviations Abbreviated term used for the position designates the direction of the x-ray beam. Abbreviated term used for the position designates the direction of the x-ray beam. First letter states where the x-ray beam enters the body, the second designates where it exits. First letter states where the x-ray beam enters the body, the second designates where it exits. V/D – enters ventrally and exits dorsally V/D – enters ventrally and exits dorsally DMPaLO- indicates that carpus is rotated to a selected -degree angle and the central x-ray enters the dorsal/medial surface and exits the palmar/lateral surface. DMPaLO- indicates that carpus is rotated to a selected -degree angle and the central x-ray enters the dorsal/medial surface and exits the palmar/lateral surface.

10. Basic Criteria of Positioning Refrain from overt physical restraint Refrain from overt physical restraint Primary goal is to produce a good quality radiograph of the area being examined. Primary goal is to produce a good quality radiograph of the area being examined. Factors to consider: Factors to consider: 1. Welfare of the patient. 1. Welfare of the patient. 2. Restraint and immobilization of the patient. 2. Restraint and immobilization of the patient. 3. Minimal trauma to area of interest. 3. Minimal trauma to area of interest. The least risk of exposing those assisting with the examination to radiaton. The least risk of exposing those assisting with the examination to radiaton.

11. Patient factors The comfort and welfare of the patient should be considered at all times. The comfort and welfare of the patient should be considered at all times. PATIENCE!!!!!! PATIENCE!!!!!! Radiography can be frightening to animal. Radiography can be frightening to animal. Noises of prep and of x-ray can be very disconcerting. Make sure take into consideration when taking radiographs. Noises of prep and of x-ray can be very disconcerting. Make sure take into consideration when taking radiographs.

12. How to handle animals Handle in a slow, quiet, manner. Handle in a slow, quiet, manner. Use a calm, soft voice and reassure animals through touch. Use a calm, soft voice and reassure animals through touch. Avoid quick, loud movements. Avoid quick, loud movements. Avoid and severe restraint. Avoid and severe restraint.

13. Prep sounds When depressing prep button, machine will make noise. It is good idea to let patients hear this sound as you are positioning so as to avoid the frightening newness of the sound once the radiograph is taken. When depressing prep button, machine will make noise. It is good idea to let patients hear this sound as you are positioning so as to avoid the frightening newness of the sound once the radiograph is taken.

14. General Positioning May require sedation, general anesthesia, and positional devices May require sedation, general anesthesia, and positional devices All essential anatomical regions should be included in the primary beam when taking x-rays All essential anatomical regions should be included in the primary beam when taking x-rays PRIMARY GOAL- to find the most comfortable posture/position for the animal to produce an accurate reproduction of the area of interest PRIMARY GOAL- to find the most comfortable posture/position for the animal to produce an accurate reproduction of the area of interest

15. PREPARATION!!! Prepare, prepare, prepare Prepare, prepare, prepare Prior to radiograph being taken make sure: Prior to radiograph being taken make sure: Correct patient is present Correct patient is present All chemicals and processor are in working order. All chemicals and processor are in working order. That cassette is positioned appropriately. That cassette is positioned appropriately. That identifying markers are in place. That identifying markers are in place.

16. Measurement Caliper- measuring device for anatomic area of interest. Caliper- measuring device for anatomic area of interest. Measures area in centimeters Measures area in centimeters If unsure, always measure thickest spot. If large differences in sizes exist, may have to take two separate radiographs. If unsure, always measure thickest spot. If large differences in sizes exist, may have to take two separate radiographs.

17. Required Views Radiograph is a two dimensional picture of a three- dimensional structure. Radiograph is a two dimensional picture of a three- dimensional structure. Therefore two views must be taken at right angles to one another in order to get a good idea of structure of anatomy. Therefore two views must be taken at right angles to one another in order to get a good idea of structure of anatomy. 2 views will help you see something that you might miss on 1 view 2 views will help you see something that you might miss on 1 view Area of interest closest to film Area of interest closest to film Minimizes distortion and magnification Minimizes distortion and magnification Comparison Comparison To compare to other area to see if there are any pathological changes To compare to other area to see if there are any pathological changes

18. Splitting the Cassette Taking more than 1 picture on a cassette Taking more than 1 picture on a cassette You need to place lead over the “non-used” portion of the cassette, take the exposure, remove the lead, cover the “exposed” side and expose the “non-exposed” side You need to place lead over the “non-used” portion of the cassette, take the exposure, remove the lead, cover the “exposed” side and expose the “non-exposed” side Lead gloves can be used – inexpensive, handy Lead gloves can be used – inexpensive, handy Not practical when using bucky tray Not practical when using bucky tray Split as many times as you have room Split as many times as you have room The 2 views need to be in the same direction The 2 views need to be in the same direction

19. Collimation, Collimation, Collimation Very important Very important Decreases the amount of scatter Decreases the amount of scatter Which increases the amount of contrast Which increases the amount of contrast Have you heard this before?????? Have you heard this before??????

20. Positioning Guidelines Should be Taken over Thickest area Should be Taken over Thickest area General Rule: General Rule: The center of the primary beam (+) should be directly in the center of the area of interest. The center of the primary beam (+) should be directly in the center of the area of interest. CASSETTE SIZE IS IMPERATIVE CASSETTE SIZE IS IMPERATIVE Specific anatomy must be included for each anatomic area. Specific anatomy must be included for each anatomic area. Long bones should include the shaft of the bone, as well as the joint above and the joint below Long bones should include the shaft of the bone, as well as the joint above and the joint below Joints should have the beam centered over the joint space, and the small portion of long bones above and below the joint. Joints should have the beam centered over the joint space, and the small portion of long bones above and below the joint.

21. Patient Preparation Clean & dry hair coat Clean & dry hair coat Removal of splints, bandage material, collars, leashes, etc. Removal of splints, bandage material, collars, leashes, etc. Chemical restraint is preferred but not always allowed Chemical restraint is preferred but not always allowed No matter how good an animal seems, always expect the worse No matter how good an animal seems, always expect the worse Use of positioning devices Use of positioning devices Sandbags, foam blocks, wood blocks, trough, tape, gauze, rope Sandbags, foam blocks, wood blocks, trough, tape, gauze, rope Positioning devices should not be placed directly above or below area of interest – not completely radiopaque Positioning devices should not be placed directly above or below area of interest – not completely radiopaque

23. Film Identification Proper labeling of a radiograph is mandatory for legal and practical reasons. Proper labeling of a radiograph is mandatory for legal and practical reasons. Should include: Should include: Appropriate patient identification Appropriate patient identification Appropriate markers (R ) (L) and view if necessary. Appropriate markers (R ) (L) and view if necessary. Should mark side that is down on the patient. Should mark side that is down on the patient. Lateral projections of the leg should have the marker placed cranially to the leg. Lateral projections of the leg should have the marker placed cranially to the leg.

24. Views Standard is a lateral view and v/d or d/v view. Standard is a lateral view and v/d or d/v view. Oblique view Oblique view Patient is rotated – not the tube head Patient is rotated – not the tube head Degree of angulations varies on area of interest – usually pretty minimal = 10 to 15 degree’s Degree of angulations varies on area of interest – usually pretty minimal = 10 to 15 degree’s They allow for a more dimensional view They allow for a more dimensional view Eliminates superimposition Eliminates superimposition Comparison Views Comparison Views Compare R w/ L Compare R w/ L Young animals, extremities – most common Young animals, extremities – most common Helpful to do both projections on 1 film Helpful to do both projections on 1 film