Skull Radiographic Views and Anatomy Flashcards
what are skull radiographs used for
assessing maxillofacial trauma
what are the main types of skull radiograph
occipitomental
postero-anterior mandible
reverse townes
true lateral skull
what is the difference between a lateral ceph and a true lateral skull
true lateral skull is not standardised using a cephalostat
what is special about the positioning of the skull x-ray machines
they can be positioned to capture the patient at different angles (even if the patient is bed bound and cannot stand up)
what type of receptor is used for skull x-rays
digital
what reference line is used for skull radiographs
orbitomeatal
where does the orbitomeatal line extend to
outer canthus of eye to centre of external auditory meatus
what does an occipitomental radiograph show
facial skeleton avoiding superimposition of skull base
what are occipitomental radiographs used for
middle third facial fractures
how many angles do you use for an occipitomental radiograph
2
what are the indications for an occipitomental radiograph
middle third fractures (le fort, zygomatic complex, naso-ethmoidal complex, orbital blow-out)
coronoid process fractures
how do you position a patient for an occipitomental radiograph
face towards receptor
head tipped back so orbitomeatal line at 45 degrees to receptor
nose-chin position
what does a posterio-anterior mandible radiograph show
posterior parts of mandible
why is a postero-anterior mandible radiograph not suitable for viewing the facial skeleton
because of superimposition of base of skull and nasal bones
what are the indications for a postero-anterior mandible radiograph
lesions and fractures involving posterior third body, angles, rami, low condylar necks
mandibular hypoplasia, hyperplasis
maxillofacial deformities
how do you position the patient for a postero-anterior radiograph
face towards receptor, head tipped forward
forehead-nose position
why is the x-ray beam projected from the posterior part of the skull
reduced magnification of face = less distortion of structures
reduced effective dose = x-ray beam partly attenuated by back of skull before hitting soft tissues
what does a reverse townes radiograph show
condylar heads and necks
what is the difference between a reverse townes and a postero-anterior radiograph
mouth is open with reverse townes
what are the indications for reverse townes radiograph
high fractures of the condylar necks
intrascapular fractures of TMJ
condylar hypoplasia/hyperplasia
how do you position the patient for a reverse townes radiograph
face towards receptor
forehead-nose position
mouth open
what does opening the mouth do in a reverse townes radiograph
moves the condylar heads out of the glenoid fossa
