Radiography of the skull Flashcards
FO 30 means:
Fronto-occipital: (Townes)
OF 20 means:
Occipito-frontal: (Caldwell’s)
FO 30 (Townes) rotation:
symmetrical petrous ridges indicate no rotation. Smaller line between foramen magnum and lateral skull wall indicates rotation in that direction
FO 30 (Townes) angulation:
Correct: Dorsum sellae and post. clinoid processes shown in foramen magnum
More than 30 angle (chin too far down): Dorsum sellae projected below foramen magnum
Less than 30 angle (chin too elevated): Dorsum sellae projected above the foramen magnum
OF 20 (caldwell’s) rotation:
Look at distances between midlateral orbit to lateral wall of cranium –> the shorter distance indicates rotation in that direction.
FO 20 (Caldwell’s):
Alternative for OF 20. In FO facial features are magnified –> look at orbits
Lateral skull tilt:
Look at orbital roofs, they should be superimposed. Inter-pupillary line must be perpendicular with IR
Lateral skull rotation:
Look at anterior cranial cortices and greater sphenoid wings, they should be superimposed. MSP must be parallel with IR
Lytic lesion
Lytic: Destruction of an area of bone due to a disease process (eg cancer)
x-ray image appearance: Dark circles on skull. If margins are not well defined it indicates matastatic cancer
Multiple myeloma
Haematologic (blood) cancer
x-ray image appearance: many dark patches
Pagets disease
Abnormal enlargement and weakening of bone
fluffy appearance appearance on x-ray
Acromegaly
Too much growth hormone produced after puberty
Pituitary gland tumour
Spitz-holter valve/shunt
Tube line/valve to treat hydrocephalus
–> increased retention of CSF within the cranium. The shunt relieves pressure. More common in kids
Pneomoencephalus
Air in cranial cavity (HBL)
FO 30 (Townes) purpose:
To project facial features away from the occipital bone
