skull radiographic views + anatomy Flashcards
What are skull radiographs commonly used for?
Assessing maxillofacial trauma
What is now used more commonly than skull radiographs?
CT or CBCT
What are the main types of skull radiographs?
Occipitomental (OM)
Postero-anterior mandible (PA mandible)
Reverse Townes
True lateral skull
What specialist equipment is needed for skull radiographs and why?
X-ray machine - can be positioned to capture patient at different angles which is valuable in trauma cases, patient can be upright or lying down
Receptor - digital and large enough to capture entire head including jaws
What line is used to position most skull radiographs and where does it run?
Orbitomeatal line
Runs from the outer canthus of the eye to the centre of the EAM
What does an OM radiograph show?
The facial skeleton, avoiding superimposition of the skull base
What are the indications for an OM radiograph?
Middle third fractures eg - Le Fort I, II and III or zygomatic complex
Coronoid process fractures
How is a patient positioned for an OM radiograph?
Face towards receptor - nose and chin
Head tipped back so OM line is 45º to receptor
X-ray beam at varying angle from 0º to 40º
2 images taken at different angles
What important anatomy is assessed in an OM radiograph?
Orbital rim
Zygomatic arch
Infraorbital foramen
Maxillary sinus
Coronoid process
What does a PA mandible radiograph show?
Posterior parts of mandible - rami and bodies
Superimposition of base of skull and nasal bones so not suitable for viewing facial skeleton
What are the indications for a PA mandible radiograph?
Lesions and fractures involving posterior third of body, angles, rami and low condylar necks
Mandibular hypoplasia/hyperplasia
Maxillofacial deformities
How is the patient positioned for a PA mandible radiograph?
Face towards receptor (forehead and nose)
Head tipped forwards so OM line perpendicular to receptor
X-ray beam perpendicular to receptor, centred at rami
In skull radiographs, why does the X-ray beam come from the posterior side?
Reduced magnification of anatomical structures of the face since they’re closer to the receptor (reduced distortion)
Reduced effective dose - lower radiation dose to radiosensitive tissue eg - lens of eye
What anatomy is important in a PA mandible radiograph?
Posterior mandible
What is a Reverse Townes radiograph used for?
Shows condylar heads and necks when suspected fractures or abnormalities
