1. SMALL ANIMAL SKULL Chapter 23
Credits: Unless otherwise indicated the photographs and radiographs are courtesy of Seneca College, King City, ON, Veterinary Technician Program.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

2. CHAPTER OUTLINE Objectives Key terms Overview
Protocol for skull radiography
Positions and anatomy
Lateral
Dorsoventral
Ventrodorsal
Further views
Key points
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

3. Objectives Positions and principles Safely and properly position
Measure, central ray, borders
Optional views
Normal radiographic anatomy
When you have finished this chapter, you will be able to:
1. Know the common positions and principles used to radiograph the small animal skull.
2. Properly and safely position a dog or cat for the various common positions of the skull with an emphasis on where to measure and center the beam, where the borders are, and how to properly position so that the body part is parallel to the film and both are perpendicular to the central ray.
3. Understand other views that may need to be completed as an alternative.
4. Identify the normal anatomy found on a radiograph.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

4. Key Terms Brachycephalic Dolichocephalic Mesocephalic Rostrocaudal
Skyline
Brachycephalic: Having a short and wide head, such that the length of the cranium is shorter than the width (from the Greek brachy, “short,” and cephal, “head”).
Dogs with short and wide heads such as bulldogs.
Even though the mandible is also shorter than normal, the relationship of the upper and lower jaw is such that the lower jaw often is longer than the upper jaw often resulting in crowded and rotated teeth and sometimes a malocclusion, meaning the upper and lower teeth do not fit well together when the animal closes his mouth.
Dolichocephalic: Dogs that have long, narrow heads and tapered muzzles such as collies. Sometimes this narrow head conformation is associated with malocclusions in which the upper teeth do not overlap the lower teeth properly (from dolich/o- (G) long and cephal- (G) head).
Mesocephalic: Refers to the majority of dogs with a medium or average head shape where the width and length of the head is in balance, so that the skull is about twice as long as it is wide (from mesi-(G) – middle and cephal- (G) - head). Sometimes also referred to a mesatacephalic (Golden Retriever).
Rostrocaudal : In dental terminology, the direction of the beam coming from the nose to the back of the throat (from rostri (L) beak and caud/o (L) toward the tail).
Skyline: term referred to when imaging the patellar bones without obliteration by other bones
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

5. Overview Heavy sedation or general anesthesia Breed variations
Generally symmetrical
Thickest part—measure and cathode
High contrast
Grid—over 11 cm
Collimate
Positioning devices
Identify and place markers
Heavy sedation or general anesthesia will be required for most patients for views other than the routine lateral and dorsoventral survey.
ET, tongue, and pinnae could all cause dense shadows that may interfere with the diagnosis.
Skull is relatively symmetrical and, in most small animals ( mesatocephalics), approximately the same width in lateral and dorsoventral/ventrodorsal dimensions.
Measure at the widest area of the cranium.
If air-filled sinus cavities are to be radiographed, measure just rostral to the thickest part of the cranium to avoid overexposure.
High-contrast exposure is recommended.
Use a grid for measurements over 11 cm.
Tightly collimate to the primary area of interest to reduce scatter radiation and to improve the image quality.
Keep the thickest part of the skull toward the cathode.
No special preparation is required other than cleaning the hair coat and removing any collar or halter.
Radiolucent wedges extra-oral oblique radiographs of the mandible and maxilla.
Place the appropriate marker toward the nose.
Both markers for oblique images -dependent jaw.
The markers also help identify the different quadrants of the teeth.
The oblique mandible and maxilla views are further discussed in the Chapter 24.
Most disease processes of the skull are not bilateral so need a true lateral, DV, VD views,
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

6. Skull Terminology Left Rostral-Right Caudal Oblique- LeR-RtCdO
Left Dorsal-Right Ventral Oblique LeD-RtVO
Redrawn from Kus S, Morgan J: Radiography of the canine head: optimal positioning with respect to skull type. Vet Radiol 26: , 1985.
Remember the rules of nomenclature if the full term or its abbreviations are used.
The first part of the term before the hyphen is where the central ray enters the body.
This part of the body is closest to the tube head.
The part after the hyphen is where the central ray exits. This is the body part closest to the table or image receptor.
 A, LeR-RtCdO: Left rostral–right caudal oblique view.
The beam is entering rostrally(from the nose) on the left side of the skull (LeR).
The beam exits on the caudal aspect (back)of the skull on the patient’s right side (RtCd).
Central ray is not on the transverse plane, =oblique view (O).
The most accurate description, which includes the angle of the beam from perpendicular (20 degrees), is Le20 R-RtCdO.
B, LeD-RtVO: Left dorsal–right ventral oblique view.
The central ray enters the skull dorsally (from the top of the head) on the patient’s left side (LeD) and exits the skull ventrally(towards the chin) on the patient’s right side (V).
Because the skull is not in a true lateral position, it is an oblique (O).
Thus the patient is lying in right lateral recumbency in a dorsoventral oblique position;
its nose is pointing to the table.
The most accurate description is Le10D-RtVO.
This locates the entrance angle at 10 degrees dorsal to the dorsal plane through the area of interest such as for the left temporomandibular joint .
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

7. Skull Terminology Rostroventral-Caudodorsal Oblique RV-CdDO
Rostrodorsal-Caudoventral Oblique RD-CdVO:
Redrawn from Kus S, Morgan J: Radiography of the canine head: optimal positioning with respect to skull type. Vet Radiol 26: , 1985.
C, RD-CdVO: Rostrodorsal-caudoventral oblique view of the maxillary incisor teeth.
The central ray:
Enters the maxilla directly from the front at the dorsal aspect of the skull (RD)
Exits toward the back of the skull down toward the ventral side (CdV) at an angle (O).
For example:
The “R75D” indicates that the beam is angled at 75 degrees dorsal to the dorsal plane through the area of interest.
The image receptor is inside the mouth.
D , RV-CdDO: Rostroventral-caudodorsal oblique view.
Enters from inside the mouth or the front and ventral aspect of the head (RV)
Exits toward the back and top of the head (CdD) at an angle (O) 20 degrees ventral from the plane of the hard palate.
R20V-CdDO (open mouth) is a more accurate description.
This view can also be used for the temporomandibular joints.
The patient is lying on its back -nose pointing towards the tube head.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

8. Canine Skull
FIGURE 23-2
Skull of the dog. A, Lateral view. B, Dorsal view.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

9. Three Basic Skull Shapes
Reprinted with permission from Aspinall V, Cappello M: (2009). Introduction to veterinary anatomy, London, Butterman-Heineman.
FIGURE 23-3
A) Brachycephalic- Having a short and wide head, such that the length of the cranium is shorter than the width
From the Greek brachy, “short,” and cephal, “head”
(B) Mesaticephalic, = Normal occlusion and function of a scissor or shear bite with the maxillary incisors rostral.
Describes the majority of dogs with medium or average head shape in which the width and length of the head are in balance,
From Greek mesi- “middle,” and cephal, “head”.
Also referred to as mesocephalic.
(C) Dolichocephalic =Having a long, narrow head such that the cranial length is greater than the cranial width
From Greek dolich/o-, “long,” and cephal-, “head”
The positions of the maxillary and frontal sinus are also shown.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

10. Remember Your Checklist
Settings, image receptor, correct body part, center, and borders correct, collimate
Label placement
Measure at
Measure in
Central ray
Parallel
Perpendicular
Quickly go through your mental checklist before pushing the exposure button; the checklist includes the following items:
Settings correct
Image receptor/machine/grid in position
Proper location of markers and identification (ID) (if using at this stage)
Correct body part and view
Properly centered
Borders correct and collimated
Thickest part to the cathode
Patient properly prepared, positioned, and restrained so the image will be perpendicular to the beam and parallel to the film
The label is in the field of view but do not obliterate important structures (VD)
Measure at the thickest part of the area to be radiographed
Always measure the patient in the position in which it is to be x-rayed
Always have the center ray at the area of interest
Lateral - When viewing the skull in a rostrocaudal direction, an imaginary line drawn through the medial canthi of the eyes should be perpendicular to the tabletop.
DV: When viewing the skull in a rostrocaudal direction, an imaginary line drawn through the medial canthi of the eyes should be parallel to the tabletop
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

11. Skull Lateral View Measure Central Ray Borders
Place the affected side closer to the table.
MEASURE (on the area of interest):
Survey: Highest point of the zygomatic arch at the center of the cranium .
Temporomandibular Joint: Highest point of the zygomatic arch over the joint.
Tympanic Bullae: Highest point of the zygomatic arch over the bullae.
Nares: Highest point of the zygomatic arch just rostral to the medial canthi.
CENTRAL RAY (on the area of interest):
Survey: Lateral canthus of eye. Midway between the eye and ear, or on area of interest.
Temporomandibular Joint: Center just rostral to the ears
 Tympanic Bullae: Palpate center on the base of the ear
Teeth and Nares: Just rostral to the lateral canthus.
BORDERS (depends on the area of interest):
Survey: Full skull—tip of the nose to the occipital protuberance.
Tympanic Bullae: Cranial and caudal to the ear.
Temporomandibular Joint: Cranial and caudal to the joint.
Teeth and Nares: Tip of the nose to the lateral canthi.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

12. Skull Lateral Positioning Place Limbs Head/Neck/Sternum Comments/Tips
Place In: Right or left lateral recumbency with the affected side to the image receptor.
Hind Limbs: Leave in a natural position; support with a sandbag or ties if needed.
Forelimbs: Pull caudally, and support with a sandbag or ties.
Head and Neck: Position the head so that the mandible is parallel to the long edge of the image receptor.
Put foam under the cranioventral cervical region.
Place a foam pad under the ramus of the mandible to superimpose the rami and to prevent rotation of the skull.
Tape the head over the nose and neck area so that the tape is extended across the table.
A sandbag may be placed over the neck and against a foam pad at the dorsal aspect of the head to keep the head in position.
TECHNICIAN NOTES
Pads under the nose and neck will help keep the skull in a horizontal plane and minimize rotation.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

13. Skull Lateral View Comments and Tips
When viewing the skull in a rostrocaudal direction, an imaginary line drawn through the medial canthi of the eyes should be perpendicular to the tabletop.
The rami of the mandible and the tympanic bullae should be superimposed on the image.
The nasal septum should be parallel to the image receptor and tabletop.
Ensure that the pinnae of the ears and tape are not superimposed over areas of interest.
Pulling the pectoral limbs caudally may help keep the skull in a true lateral position.
Radiograph of the left lateral brachycephalic skull. Note the superimposition of the bones and teeth in a true lateral view
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

14. Skull Dorsoventral View
Measure
Central ray
Borders
MEASURE (on the area of interest):
Survey: Highest point of the cranium just caudal to the lateral canthi.
 Temporomandibular Joint: Rostral to the ears on the dorsal midline of the skull.
 Tympanic Bullae: Highest point of the cranium just caudal to the lateral canthi.
 Nares: Rostral to the medial canthi.
CENTRAL RAY (on the area of interest):
Survey: Between the two lateral canthi of the eyes on the sagittal crest or on the area of interest
.Temporomandibular Joint: Center just rostral to the ears on the dorsal midline of the skull.
 Tympanic Bullae: Palpate the base of the ear and center on the dorsal midline between the ears.
Teeth and Nares: Center more rostral.
BORDERS (depends on the area of interest):
Survey: Tip of the nose to the occipital protuberance.
Tympanic Bullae: Cranial and caudal to the ear.
Temporomandibular Joint: Cranial and caudal to the joint.
Teeth and Nares: Tip of the nose to lateral canthi.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

15. Skull Dorsoventral View
Positioning
Place
Limbs
Head/Neck/Sternum
Place In: Sternal recumbency in a V-trough if required.
Hind Limbs: Place in a natural position and support them with a sandbag or ties.
Forelimbs: Pull caudally or leave them in a natural position alongside the head, out of the field of view; support them with a sandbag or ties.
Head and Neck:
Extend the neck and head.
Place a sandbag over the neck for support being careful not to restrict breathing.
Tape across the nasal septum and the cranium to keep the sagittal plane of the head perpendicular to the image receptor.
Make sure the ears are positioned laterally equidistant from the head.
To maintain symmetry for the DV view,
Look from the rostrocaudal direction.
Ensure that an imaginary line drawn between the medial canthi is parallel to the table.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

16. Skull Dorsoventral View
Comments/Tips
When viewing the skull in a rostrocaudal direction, an imaginary line drawn between the medial canthi should be parallel to the table.
To prevent unwanted shadows, minimize the use of tape over the area of interest.
Have the thickest part of the skull toward the cathode to help diminish changes in opacity.
The endotracheal tube can be left in place, with the possibility of its causing a shadow kept in mind.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

17. Normal Feline Skull TECHNICIAN NOTES
To be more efficient for any view, ensure that the body parts that are not in the beam are positioned and secured first. Position the area of interest last.
Radiographic anatomy of the normal feline skull, lateral and dorsoventral projections.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

18. Skull Ventrodorsal View
Measure
Central ray
Borders
This view is used for a routine skull radiograph and for evaluation of the nasal sinus because the nasal passages are located dorsally.
MEASURE (on the area of interest):
Survey: Highest point of the cranium just caudal to the lateral canthi.
Temporomandibular Joint: Rostral to the ears on the dorsal midline of the skull.
Tympanic Bullae: Highest point of the cranium just caudal to the lateral canthi.
Nares: Rostral to the medial canthi.
CENTRAL RAY (on the area of interest):
Survey: Between the two lateral canthi of the eyes on the sagittal crest, or on area of interest.
 Temporomandibular Joint: Center just rostral to the ears on the dorsal midline of the skull.
 Tympanic Bullae: Palpate the bases of the ears, and center on the dorsal midline between the ears.
Teeth and Nares: Center more rostral.
BORDERS (depends on the area of interest):
Survey: Tip of the nose to the occipital protuberance.
 Tympanic Bullae: Cranial and caudal to the ear.
Temporomandibular Joint: Cranial and caudal to the joint.
 Teeth and Nares: Tip of the nose to the lateral canthi.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

19. Skull Ventrodorsal View
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck/Sternum
Positioning
Place In: Dorsal recumbency in a V-trough if required, and support with sandbags.
Hind Limbs: Leave the hind limbs in a natural position, and support with sandbags or ties.
Forelimbs: Pull the front limbs caudally, lateral to the chest, and support with sandbags or ties.
Head and Neck:
Position a foam pad or sandbag under the neck so that the hard palate is parallel with the image receptor.
Place a small foam pad under the nose, and tape across the mandible to keep the head aligned with the table.
TECHNICIAN NOTES
For the VD view, extend the neck so that the nose is horizontal with the table.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

20. Skull Comparison Ventrodorsal Dorsoventral Comments/Tips
Note the location of the tongue so that it does not create objectionable shadows on the area of interest.
Ensure that there is symmetry of the head.
True symmetry in a lateral view of a normal patient has been achieved:
There appears to be only one structure on the image because the two sides are superimposed on each other.
True symmetry in a DV/VD view of a normal patient has been achieved:
Left and right sides are mirror images.
Different exposures are used.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

21. Skull Ventrodorsal View Open Mouth—Nasal Sinus
Measure
Central ray
Borders
The ventrodorsal open-mouth view images the nasal sinus and ethmoid regions without superimposition of the mandible.
The position can be used only if the tube head is movable or can rotate.
TECHNICIAN NOTES
“Rostroventral-caudodorsal oblique- (R20-30V-CdD0) (open-mouth)” means that the central ray enters the body from the nose ventrally at an angle of 20 to 30 degrees and then exits obliquely toward the patient’s back in a caudal direction.
MEASURE:
At the thickest area near the commissure of the lip (over the level of the third maxillary premolar).
CENTRAL RAY:
On the nasal cavity—at the back of the palate. Angle the tube head rostrocaudally.
BORDERS:
Tip of the maxilla to the pharyngeal region (all of the upper palate).
B, Overlay and radiographic anatomy of the ventrodorsal open-mouth view.
In a rostrocaudal direction
Tilt the tube head about 20 to 30 degrees in relation to the table
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

22. Skull Ventrodorsal View Open Mouth—Nasal Sinus
Positioning
Place
Limbs
Head/Neck
Positioning
Place In: Dorsal recumbency in a V-trough if required, and support with sandbags.
Hind Limbs: Natural position, and sandbag or secure them to the table with ties.
Forelimbs: Pull caudally, lateral to the chest, and support them with sandbags or ties.
Head and Neck:
Place a small foam pad under the nose, hard palate parallel to the table.
Position a strip of tape inside the mouth and securely adhere the ends to the table in a cranial direction so the maxilla is parallel to the table.
Open the mouth wide by securing tape or gauze around the mandible and pulling caudally and ventrally.
Depending on how wide the mouth is opened, the beam should be directed at 20 to 30 degrees from the vertical into the mouth and parallel to the mandible.3
FIGURE 23-9
A, Positioning for the ventrodorsal open-mouth view (rostroventral-caudodorsal oblique; -(R20-30V-CdDO) open-mouth) for the nasal sinuses.
For the nasal sinuses
Patient in a VD position and open the mouth.
Keep the maxilla parallel to the table.
Tilt the tube head.
The collimator light should be on the hard palate back to the rear molars, and the image receptor must capture the primary beam.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

23. Skull Ventrodorsal View Open Mouth—Nasal Sinus
Comments/Tips
Radiograph courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
Comments and Tips:
This position is similar to the ventrodorsal view except that the mouth is kept open and the tube head is angled.
Decrease the kilovoltage peak (kVp) slightly from that on the skull chart to account for decreased density.
The mouth can also be propped open with a tongue depressor, plastic speculum, or 1-mL syringe barrel placed between or over the canine teeth.
Secure the ET tube to the mandible -prevents shadows on the area of interest.
The positioning device, tongue, and endotracheal tube may cause shadows.
Keep the pinnae equally lateral to the head.
In normal healthy patient
Nasal opacity and turbinate detail equal on both sides of the head.
Brachycephalic breeds: see next slide
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

24. Skull Ventrodorsal View Open Mouth—Brachycephalic Breeds
Not as effective in brachycephalic breeds
Use closed mouth CdV-RDO
Redrawn from Kus S, Morgan J: Radiography of the canine head: optimal positioning with respect to skull type. Vet Radiol 26: , 1985.
For brachycephalic breeds a better projection to image the nasal cavity:
Closed-mouth caudoventral-to-rostrodorsal oblique- CdV-RDO
Nose (hard palate) tipped down toward the film approximately 30 degrees and the vertical beam centered 2-3 cm rostral to the angular processes of the mandible 3
FIGURE A, The ventrodorsal open-mouth view (rostroventral-caudodorsal oblique) is not as effective at imaging the nasal cavity in brachycephalic breeds .
B, The closed-mouth caudoventral- rostrodorsal oblique (CdV-RDO) projection is more satisfactory. The nose (hard palate) is tipped down toward the film about 30 degrees with the central beam 2 to 3 cm rostral to the angular processes of the mandible .
Comments and Tips
Similar to the VD view except that the mouth is kept open and the tube head is angled.
Decrease kVp slightly from that on the skull chart to account for decreased density.
Can also prop mouth open with a tongue depressor, plastic speculum, or 1-mL syringe barrel placed between or over the canine teeth.
Secure the ET tube to the mandible -prevents shadows on the area of interest.
The positioning device, tongue, and endotracheal tube may cause shadows.
Keep the pinnae equally lateral to the head.
On a normal healthy patient, the nasal opacity and turbinate detail should be equal on both sides of the head. .
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

25. Skull Frontal View 90º RCd—Closed Mouth
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck
This rostrocaudal view images the frontal sinuses.
MEASURE:
Over the site of the nasal sinuses (nasal stop).
CENTRAL RAY:
Between the eyes (on the frontal sinuses).
BORDERS:
Occipital crest to the dorsal aspect of the nasal planum (tip of nose).
TECHNICIAN NOTES
Keep the nose straight up and pointed at the tube head for the frontal sinuses in medium- and long-nosed dogs.
Positioning
Place In: Dorsal recumbency in a V-trough if required; support with sandbags.
Hind Limbs: Leave in a natural position and secure with sandbag or ties.
Forelimbs: Pull the front limbs caudally, lateral to the chest, and support with a sandbag or ties.
Head and Neck: Position a foam pad or sandbag under the neck so that the hard palate is perpendicular with the image receptor.
Point the nose up so it is perpendicular to the image receptor and to the long axis of the body.
Keep it in position by placing tape, tubing or gauze around the nose.
Secure caudally, keeping the nose pointed up.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

26. Skull Frontal View 90° Rostrocaudal—Closed Mouth Frontal Sinuses
Radiograph courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
Comments and Tips
The hard palate should be perpendicular to the table. An imaginary line joining the medial canthi of the eyes should be parallel to the image receptor.
Note the location of the tongue so it does not create objectionable shadows on the area of interest. .
Reduce the kVp because there is minimal tissue to penetrate.
Another term for this view is skyline view.
Mesaticephalic and dolichocephalic breeds usually have a well-developed frontal sinus.
For brachycephalic breeds:
Take a lateral radiograph:
If no recognizable frontal sinus on a lateral radiograph
Rostrocaudal image will not be useful.1
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

27. Skull Rostral 30° Dorsal-Caudoventral Oblique View
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck
Comments/Tips
The rostrocaudal closed-mouth or fronto-occipital view demonstrates the foramen magnum, cranial vault, calvarium, and sagittal crest.
MEASURE:
At the site of the frontal sinuses.
CENTRAL RAY:
Midway between the eyes so that the cranium is centered and the beam is perpendicular to the image and table.
BORDERS:
Entire cranium.
Positioning
Place In: Position the body in dorsal recumbency in a V-trough if required, and support with sandbags.
Hind Limbs: Leave in a natural position; support with sandbags or tie if needed.
Support as for the front limbs.
Forelimbs: Pull caudally, lateral to the chest; support with sandbags or ties.
Head and Neck:
Point the nose upward and apply a long strip of tape to the nose.
Angle the hard palate in a caudal direction toward the chest by pulling on the tape and securing it caudally.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

28. Skull Rostral 30° Dorsal-Caudoventral Oblique View Foramen Magnum
Radiograph courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
TECHNICIAN NOTES
The eyes are looking up at the tube head for both the frontal sinuses and foramen magnum in the rostrocaudal views.
The difference is that the nose is pointing caudally for a view of the foramen magnum.
Comments and Tips
The central ray should pass through the canal center and parallel to its walls.
The central ray should be directed at an angle of 30 degrees to the dorsum of the nose or at an angle of 45 degrees to the hard palate.3
The actual angle depends on the type of skull.
This position is the same as the rostrocaudal frontal sinus view except that the nose is pulled more caudally.
The tongue and endotracheal tube may cause shadows. Try to keep the pinnae equally lateral to the head.
The beam should intersect at an angle with the bridge of the nose.
Some sources suggest that the nose should be positioned down for an occipitofrontal projection
Central ray -junction of the right and left frontonasal sutures for dolichocephalic and mesaticephalic breeds
About the top of the nasal fold for brachycephalic breeds.3
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

29. Skull Rostral 10-30 Degrees Ventral-Caudodorsal Oblique
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck
Comments/Tips
The rostrocaudal open-mouth view demonstrates the tympanic bullae, the base of the skull, and the odontoid process. There is minimal superimposition of the petrous temporal bone.4
MEASURE:
At the commissure of the mouth (level of maxillary third premolar).
CENTRAL RAY:
At the commissure of the mouth just dorsal to the tongue from a rostroventral direction.
BORDERS:
Entire nasopharyngeal region of the cranium.
Positioning
Place In: Dorsal recumbency in a V-trough if required, and support with sandbags.
Hind Limbs: Leave in a natural position; support with sandbags or ties if needed.
Forelimbs: Pull caudally, lateral to the chest, and support with sandbags or ties.
Head and Neck:
A small amount of padding under the neck may help keep the head in position.
Point the nose upward; apply a long strip of tape just below the maxillary canines.
Pull the nose about 10 degrees cranially, and secure.
Apply tape or gauze to the mandibular canines, + ET tube if used.
Pull and secure the tape
Mandible is about 10 degrees caudal from the perpendicular.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

30. Skull Rostral 10-30 Degrees Ventral-Caudodorsal Oblique
Radiograph courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
TECHNICIAN NOTES
Point the nose to the tube head, open the mouth, and separate the mandible and maxilla
Secure slightly in each direction -tympanic bullae of dogs in the rostrocaudal open mouth view.
Comments and Tips
Similar to the frontal sinus view, except that the mouth is opened for dogs.
The hard palate should be at a 10-degree angle from the vertical.5
Can prop mouth open with a tongue depressor, plastic speculum, or 1-mL syringe barrel placed between or over the canine teeth.
Watch for tongue and positioning devices shadows.
Try to keep the pinnae equally lateral to the head.
The beam bisects angle of the open mouth or at the junction of the hard palate and the horizontal rami of the mandible.
The bullae should be projected freely.
The angle of the beam varies with the patient and with how wide the mouth can be opened3
Brachycephalic breeds likely require a larger palatial angle (21 degrees),
Dolichocephalic breeds a smaller angle (4 degrees). Brachycephalic breeds consider:
Keep mouth closed and position as for a cat
Hard palate at a 10-degree angle from the perpendicular.1
Slightly less kVp is required -less tissue density.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

31. Skull Rostral 10 Degrees Ventral-Caudodorsal Oblique
Comments/Tips
Comments and Tips:
Cat tympanic bullae are positioned anatomically more caudally than the dog bullae
Keep the cat’s mouth closed to view the tympanic bullae and odontoid process.
Rest the dorsal aspect of the head on an angled foam wedge so that the hard palate is at an angle of 10 degrees from the vertical.
Apply tape over the maxilla to secure.
Center the beam at the level of the base of the mandibular body.5
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

32. Skull Rostral 10 Degree Ventral-Caudodorsal Oblique
For cat tympanic bullae
Radiograph reprinted with permission from Thrall DE: (2007), Textbook of veterinary diagnostic radiology, 5th ed, St. Louis, Saunders.
TECHNICIAN NOTES
Point the nose to the tube head, keep the mouth closed, and pull slightly cranially for evaluation of the tympanic bullae of feline patients.
Remember to apply the label appropriately in each image and to collimate the beam as tightly as possible.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

33. Skull Lateral Oblique LeD-RtVO
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck
Comments/Tips
The lateral oblique or LeD-RtVO (dorsoventral oblique) view with the head lying in a natural position isolates the tympanic bullae.
The maxilla is not generally raised.
MEASURE:
At the base of the ear over the tympanic bullae at the widest part of the cranium.
CENTRAL RAY:
At the base of the ear over the tympanic bullae.
BORDERS:
Cranial and caudal to the ear.
Positioning
Place In: Right or left lateral recumbency -unaffected side to the image receptor.
Right lateral—to view the left oblique tympanic bulla
Left lateral—to view the right oblique tympanic bulla
Hind Limbs: Leave the hind limbs in a natural position; support with sandbags or ties if needed.
Forelimbs: Position caudally and support with sandbags or ties.
Head and Neck:
Position the head so that the mandible is parallel to the long edge of the table.
Allow the head to lie oblique naturally with the nose pointing to the table.
If needed, tape the head over the nose and neck area, extending the tape across the table.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

34. Skull Lateral Oblique LeD-RtVO
Tympanic bullae in isolation
Image from Lavin, L, Radiography in Veterinary Technology, 4th edition, (2007), Elsevier.
TECHNICIAN NOTES
Natural oblique lateral position
Nose and the unaffected tympanic bulla closest to the table.
This could be considered a modified DV oblique view.
Comments and Tips
The degree of rotation from the true lateral depends on the species and type of skull.
There should be enough rotation to allow isolation of each tympanic bulla.
Use both labels, so that if the patient is positioned in right lateral recumbency:
Right marker (unaffected bulla) will be dorsal
Left marker (affected bulla) ventral.
This view can also be used for an oblique view of the temporomandibular joint (TMJ).
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

35. Labeling the Oblique
Radiograph courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
TECHNICIAN NOTES
When placing the positional markers for an oblique view, consider the following:
What quadrant are you attempting to image?
When that quadrant is in the correct position, look at which part of the jaw is touching the table.
Will it appear more ventral, or will it be displaced dorsally in relation to the opposite side of the jaw?
For the right mandible,
The patient is lying on its right side.
Raise the maxilla
Left side of the mandible will be tipped ventrally.
Place the R marker near the tips of the right premolars
L marker at the ramus of the left mandible.
The markers do not indicate which side the patient is lying on but, rather, the specific quadrant.
This image is an open mouth lateral oblique (LeV-RtDdO) of a skull in right lateral
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

36. Skull Lateral Oblique VDO LeV-RtDO Maxillary Teeth TB/ TMJ
Measure
Central ray
Borders
Positioning
Place
Limbs
Head/Neck
Comments/Tips
Lateral oblique (Ventrodorsal Oblique) (LeV-RtDO/RtV-LeDO) view can be used for the tympanic bullae and temporomandibular joints.
Different view of the mandibular condyle than is projected on the lateral and DV/VD views.
Also visualizes the maxillary teeth.
MEASURE: Just caudal to the lateral canthus over joint.
CENTRAL RAY: Between the caudal mandibular ramus and the base of the ear.
BORDERS: Cranial and caudal to the joint.
Positioning
Place In: Right or left lateral recumbency with the affected side to the image receptor.
Hind Limbs: Leave the hind limbs in a natural position; support with sandbags or ties if needed.
Forelimbs: Position caudally and support with sandbags or ties.
Head and Neck:
Mandible is parallel to the long edge of the image receptor.
Keep the skull in a straight lateral position.
Foam pad under the mandible to raise the nose from 15 degrees to 30 degrees,
Depended on the breed of dog.
The mouth can be partially opened.
If needed, tape the head over the nose and neck area, extend tape across the table.
A sandbag may be placed over the neck and against a foam pad at the dorsal aspect of the head.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

37. Skull Lateral Oblique (LeV-RtDO) TMJ and Maxillary Teeth VD Oblique—Raise the Mandible
Radiographs courtesy of Susan MacNeal, RVT, CVDT, BSc Veterinary Technician Program, Georgian College, Orillia, ON
Comments and Tips
Also called a ventrodorsal oblique view :
the nose is tipped up at an angle; beam enters the head more from the ventrodorsal aspect.
Nondependent bulla caudally and the dependent (down) bulla rostrally.
Raise mandible from the table depending on the breed. 3,6
Dolichocephalic about 10 degrees,
Mesaticephalic breeds about 15 degrees,
Brachycephalic breeds generally angle of 25 to 30 degrees
Compare both right and left lateral oblique views should be taken for comparison.
No objectionable shadows on the area of interest.
Place dependent side marker ventrally near the joint.
Nondependent side marker -dorsal to the nares
Indicates that the raised joint is dorsal to the joint on the table.
Use the skull technique chart, need more exposure for cranium.
Upper dental arcade or bony lesions of the nondependent maxilla.
For upper dental arcade: The affected maxilla is closer to the image.
Place a foam pad under the mandible, for a 30- to 45-degree angle of mandible
Mouth widely opened, and the beam is centered over the fourth premolar.
Tie ET tube should to the mandible.
Mark teeth with both positional markers
Place dependent marker ventrally, and the upper side marker dorsally.
The dependent teeth will be grayer because there is minimal superimposition of the palate.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

38. Skull Lateral Oblique LeD 20°-45° RtV /RtD 20°-45° LeVO Mandibular Teeth
DV oblique:
Raise the maxilla
Comments/Tips
Lateral Oblique View for the Mandible (LeD20-45RtVO/ RtD20-45LeVO)
For lower dental arcade or bony lesions of the nondependent mandible.
Similar to the lateral oblique except that the maxilla is raised with foam wedge.
Consider as a DV oblique view -the beam enters at the top of the head and exits on ventrally. The nose is pointing down..
Comments and Tips
The right (affected) side is down for visualizing the right mandibular teeth.
A foam pad under the maxilla, creating a 20- to 45-degree angle of the mandible with the table.
Actual angle depends on how wide the mouth is open and on the breed.
No superimposition of the affected mandibular premolars and molars by the other teeth.
Mouth widely opened, and the central ray over the fourth premolar.
The endotracheal tube is tied to the maxilla.
Label teeth with both positional markers,
Dependent marker dorsally and the upper side marker ventrally.
The dependent teeth will be grayer because there is minimal superimposition of the rami of the mandibles.
Right (20°- to 45-degree) dorsal, left ventral oblique view =right side is down,
Left (20- to 45-degree) dorsal, right ventral oblique view =left side is down.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

39. Key Points General anesthesia or sedation Symmetry
Draw imaginary line between medial canthi
Lateral view:
Dorsoventral view:
Collimate tightly
Other views
Labels and markers
Label oblique views
Side against the film vs. opposite side
Breed variations
General anesthesia or sedation is required for accurate positioning for all skull views.
It is essential that there be symmetry of the skull to minimize distortion, which could lead to misdiagnosis.
Keep anatomical structures either parallel or perpendicular to the table (depending on the radiographic view)
Center under the primary x-ray beam:
Lateral view: draw an imaginary line between the medial canthi.
This line should be perpendicular to the table.
Dorsoventral view: draw an imaginary line between the medial canthi.
This imaginary line should be parallel to the table.
Collimate tightly to the area of interest, being conscious of the placement of the labels and markers.
Views other than the standard views depend on the area of interest and the reason for imaging the patient.
Label oblique views: which part of the jaw is against the film and how the opposite side is positioned.
Breed variations change the angle for rostrocaudal projections
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.

40. Mystery Radiograph
LeV-RtDO – open mouth ( Left Ventral – right Dorsal oblique view)
This view is for the maxillary dental arcade.
The upper L marker indicates that the left side is uppermost.
The patient is lying on its right side ( the R is missing at the cusps of the right maxillary premolars)
Note that the teeth are whiter than the opposite dental arcade.
This is because of superimposition over the maxillary bone.
The right teeth are in profile.
Brown: Lavin’s Radiography for Veterinary Technicians Copyright © 2014, 2007, 2003, 1999, 1994 by Saunders, an imprint of Elsevier Inc.