Skull Radiographic Views and Anatomy

Question 1

What are skull radiographs and what are the main uses?

Answer 1

• Group of plain radiographs used mainly for
  1. Assessing maxillofacial trauma (except extensive/complex cases then use CT/CBCT)
  2. Historically assess diseases of the skull e.g. multiple myeloma = now use CT

Question 2

What are the 4 main types of skull radiographs?

Answer 2

• Occipitomental
• Postero-anterior mandible
• Reverse Towne’s
• True lateral skull (essentially a lat ceph but positioning not standardised with cephalostat)

Question 3

What skull radiographic view is this and what is it primarily used for?

Answer 3

• Occipitomental
• Used for fractures of middle third face (Top of orbit to upper teeth)
• Shows facial skeleton, avoiding superimposition of skull base

Question 4

What skull radiographic view is this and what is it primarily used for?

Answer 4

• Postero-anterior mandible
• Used for fractures of posterior mandible (excluding condyles)

Question 5

What skull radiographic view is this and what is it primarily used for?

Answer 5

• Reverse Towne’s
• Used for fractures of mandibular condyles

Question 6

What equipment is needed for skull radiographs?

Answer 6

• X ray machine unit consisting of specialised skull unit
• Digital receptor large enough to capture relevant areas (e.g. entire head including jaws

Question 7

What is an advantage to having the specialised skull unit?

Answer 7

• Can be positioned to capture pt from diff angles without pt having to move
• Pt can be erect or supine
• Useful in trauma imaging as pt may be unconscious/ drunk/ unable to move

Question 8

What is the reference line used for pt positioning in most skull radiographs?
Give me the landmarks of this line

Answer 8

• Orbitomeatal line

Landmarks
- Outer canthus of eye (edge of eye furthest away from nose)
- Centre of external auditory meatus

Question 9

What angles can occipitomental radiographs be taken? Would you take just one angle in trauma cases?

Answer 9

• 0°, 10°, 30°, 40°
• Use two together to evaluate facial trauma e.g. 10° and 40°
• AKA Waters view

Question 10

What are the indications for taking a OM radiograph?

Answer 10

Middle third fractures
- Le Fort I, II and III
- Zygomatic complex including arch
- Naso-ethmoidal complex
- Orbital blow out (floor or margins of orbit broke)

Coronoid process fractures

Question 11

What type of fracture does this image show?

Answer 11

• Le fort I

Question 12

What type of fracture does this image show?

Answer 12

• Le fort II

Question 13

What type of fracture does this image show?

Answer 13

• Le fort III

Question 14

What is the correct pt positioning for OM radiographs?

Answer 14

• Face towards receptor
• Head tipped back so orbitomeatal line is at 45° to receptor (45° to floor if pt standing)

Question 15

What is the correct positioning of x-ray beam for OM radiographs?

Answer 15

If taking 0° OM
- Beam perpendicular to receptor and centred through occiput

If taking 30° OM
- Beam 30° above perpendicular line to receptor and centred through lower border of orbit

Question 16

What type and what angulation would you suggest this radiograph is?

Answer 16

• Occipitomental radiograph
• 0-10°

Question 17

What type and what angulation would you suggest this radiograph is?

Answer 17

• Occipitomental radiograph
• 30-40°

Question 19

Label this Occipitomental radiograph

Answer 19

Question 20

What does this image show?
What does the radiograph show?
What is it not suitable for?

Answer 20

• Postero-anterior mandible radiograph
• Shows posterior parts of mandible
• Not suitable for viewing facial skeleton due to superimposition of skull and nasal bones

AKA PA jaws

Question 21

What are the indications of PA mandible radiographs?

Answer 21

• Lesions to note medio-lateral expansion
• Fractures involving
  
  • Posterior third of body
  • Angles
  • Rami
  • Low condylar necks
• Mandibular hypoplasia/hyperplasia
• Maxillofacial deformities

Question 22

What is the correct pt positioning of PA mandible radiograph?

Answer 22

• Face towards receptor
• Head tipped forward so orbitomeatal line perpendicular to receptor (and parallel to floor if pt standing)
• Called forehead-nose pos

Question 23

What is the correct positioning of x-ray beam fort PA mandible radiograph?

Answer 23

• Beam perpendicular to receptor and centred through cervical spine at level of rami

Question 24

Why is the x-ray beam projected from the posterior side in a PA mandible radiograph?

Answer 24

Reduced magnification of face since it is closer to receptor
- Less distortion of relevant structures
- Back of skull will be magnified more but this is less important

Reduced effective dose
- X-ray beam partly attenuated by back of skull before reaching face
- Lower radiation dose to radiosensitive tissues e.g. lens of eye as result

Question 25

Please label this Postero-anterior mandible radiograph

Answer 25

Question 26

What are the indications of Reverse Townes radiograph?

Answer 26

• High fractures of condylar necks
• Intracapsular fractures of TMJ
• Condylar hypoplasia/hyperplasia

Question 27

What does the Reverse Townes radiograph show? What radiograph is it similar too?

Answer 27

• Shows condylar heads and necks
• Sim to PA mandible but diff x-ray beam angle and mouth is open

Question 28

What is the correct pt positioning for Reverse Townes radiograph?

Answer 28

• Face towards receptor
• Head tipped forward so orbitomeatal line perpendicular to receptor (and parallel to floor if pt standing)
• Forehead nose position
• Mouth open !

Question 29

Why do you need to remember to ask the pt to open their mouth during a Reverse Townes radiograph?

Answer 29

• Moves condylar heads out of the glenoid fossa

Question 30

What is the correct x-ray beam positioning in a Reverse Townes radiograph?

Answer 30

• Beam 30° below perpendicular line to receptor and centred through condyles

Question 31

What is this radiograph? Label it

Answer 31

• Reverse Townes radiograph