facial bone technique Flashcards
reasons for requesting a lateral skull x-ray
skeletal surveys for NAI or myeloma
shunt series for hydrocephalus
FB demonstration
reasons for requesting a facial bones x-ray
zygomatic arch fracture
tripod fracture
orbital bow-out fracture
radiation protection to consider
ID
avoid repeats
gonad protection
LMP
what does RBL stand for
radiographic baseline
runs from the EAM to the outer canthus of the eye
what does IPL stand for
inter-pupillary lines - runs between the pupils
what does EAM stand for
external auditory meatus
what does OM stand for
occipito-mental
what does SMV stand for
sub-mento vertical
what does TMJ stand for
tempero-mandibular joint
positioning for a lateral skull
- lateral aspect of head in contact with receptor
frontal, parietal and occipital bones seen - EAM superimposed
- IPL at 90 degrees to receptor
- centering point = midway between the external occipital protuberance and the glabella - 5cm superior to the EAM
- SID is 100cm
correct positioning for a lateral skull
floor of anterior cranial fossa, anterior and posterior clinoid processes and sella turcica should be superimposed
radiographic technique for the OM
- face detector
- anterior nasal spine coincident with the midline of the detector
- outer canthus of eye and EAM should be equidistant to ensure no rotation
- IPL should be parallel to receptor
- raise patients chin to bring RBL 45 degrees to image receptor
- infra-orbital margin should be aligned to central lines
- SID = 100cm
area of interest for OM
include superior orbital margins superiorly, distal aspect of maxillae inferiorly and parietal and temporal bones laterally
correct positioning for OM
- distance between lateral orbital borders and lateral skull should be equidistant to indicate no rotation
- petrous ridge to be projected inferior to the maxillary sinus
- nasal septum should be coincident with the midline of the image
- inferior orbital margins should be on the same horizontal place and coincident with midline of the image
technique for OM 30 degrees
first steps same as OM
- centring point = upper portion of the symphysis menti due to caudal angle
- SID = 100cm
AOI for OM 30 degrees
include superior orbital margins superiorly, mandible/mastoid air cells inferiorly and parietal/temporal bones laterally
correct positioning for OM 30 degrees
distance between lateral orbital borders and lateral skull borders should be equidistant, petrous ridge projected below the maxillary sinus and orbital floor seen through maxillary sinus
what does ABC’s stand for
a= alignment b= bones c= cartilage disruption s= soft tissue
two ‘lines’ used for analysis
Dolans
McGregors
used to analyse for discontinuities and abnormalities
technique for modified OM view
- on a trolley
- supine with a vertical central ray
- centered on anterior aspect
- positioning of the RBL should be the same
- often angled cranially
- the less the chin is raised the greater the angle applied
- does not demonstrate fluid levels
technique for lateral facial bones
- lateral aspect of face in contact with receptor
- frontal bone, nasal septum, maxillae and mandible all in profile
- EAM superimposed
- IPL is at 90 degrees to receptor
- center is 2.5cm behind outer canthus of the eye along the RBL
- SID = 100cm
AOI for lateral facial bones
frontal bone superiorly, mandible inferiorly, posteriorly see the anterior portion of the parietal and temporal bone and c spine
correct positioning for lateral facial bones
include EAMs superimposed, floor of anterior cranial fossa and sella turcica should be superimposed and superimposition of tables of bone
technique for modified SMV jug handles view
- aims to get zygoma parallel to receptor rather than base of skull
- patient supine or erect, neck extended until long axis of zygoma arches are parallel to image receptor
- EAM equidistant from receptor
- centering = midway between EAMs
- head may be tilted 5-10 degrees away from side under examination
