Skull Radiographic Views and Anatomy Flashcards
What are skull radiographs and what are the main uses?
- 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
What are the 4 main types of skull radiographs?
- Occipitomental
- Postero-anterior mandible
- Reverse Towne’s
- True lateral skull (essentially a lat ceph but positioning not standardised with cephalostat)
What skull radiographic view is this and what is it primarily used for?
- Occipitomental
- Used for fractures of middle third face (Top of orbit to upper teeth)
- Shows facial skeleton, avoiding superimposition of skull base
What skull radiographic view is this and what is it primarily used for?
- Postero-anterior mandible
- Used for fractures of posterior mandible (excluding condyles)
What skull radiographic view is this and what is it primarily used for?
- Reverse Towne’s
- Used for fractures of mandibular condyles
What equipment is needed for skull radiographs?
- X ray machine unit consisting of specialised skull unit
- Digital receptor large enough to capture relevant areas (e.g. entire head including jaws
What is an advantage to having the specialised skull unit?
- 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
What is the reference line used for pt positioning in most skull radiographs?
Give me the landmarks of this line
- Orbitomeatal line
Landmarks
- Outer canthus of eye (edge of eye furthest away from nose)
- Centre of external auditory meatus
What angles can occipitomental radiographs be taken? Would you take just one angle in trauma cases?
- 0°, 10°, 30°, 40°
- Use two together to evaluate facial trauma e.g. 10° and 40°
- AKA Waters view
What are the indications for taking a OM radiograph?
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
What type of fracture does this image show?
- Le fort I
What type of fracture does this image show?
- Le fort II
What type of fracture does this image show?
- Le fort III
What is the correct pt positioning for OM radiographs?
- Face towards receptor
- Head tipped back so orbitomeatal line is at 45° to receptor (45° to floor if pt standing)
What is the correct positioning of x-ray beam for OM radiographs?
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
What type and what angulation would you suggest this radiograph is?
- Occipitomental radiograph
- 0-10°
What type and what angulation would you suggest this radiograph is?
- Occipitomental radiograph
- 30-40°
Label this Occipitomental radiograph
What does this image show?
What does the radiograph show?
What is it not suitable for?
- 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
What are the indications of PA mandible radiographs?
- Lesions to note medio-lateral expansion
- Fractures involving
- Posterior third of body
- Angles
- Rami
- Low condylar necks
- Mandibular hypoplasia/hyperplasia
- Maxillofacial deformities
What is the correct pt positioning of PA mandible radiograph?
- Face towards receptor
- Head tipped forward so orbitomeatal line perpendicular to receptor (and parallel to floor if pt standing)
- Called forehead-nose pos
What is the correct positioning of x-ray beam fort PA mandible radiograph?
- Beam perpendicular to receptor and centred through cervical spine at level of rami
Why is the x-ray beam projected from the posterior side in a PA mandible radiograph?
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
Please label this Postero-anterior mandible radiograph
What are the indications of Reverse Townes radiograph?
- High fractures of condylar necks
- Intracapsular fractures of TMJ
- Condylar hypoplasia/hyperplasia
What does the Reverse Townes radiograph show? What radiograph is it similar too?
- Shows condylar heads and necks
- Sim to PA mandible but diff x-ray beam angle and mouth is open
What is the correct pt positioning for Reverse Townes radiograph?
- Face towards receptor
- Head tipped forward so orbitomeatal line perpendicular to receptor (and parallel to floor if pt standing)
- Forehead nose position
- Mouth open !
Why do you need to remember to ask the pt to open their mouth during a Reverse Townes radiograph?
- Moves condylar heads out of the glenoid fossa
What is the correct x-ray beam positioning in a Reverse Townes radiograph?
- Beam 30° below perpendicular line to receptor and centred through condyles
What is this radiograph? Label it
- Reverse Townes radiograph