Skull X-Ray Lateral
Lateral profile of the cranial vault, sella turcica, sphenoidal and frontal sinuses in profile, anterior and posterior cranial fossae. Complementary to the PA for a complete skull examination.
Patient seated or in lateral decubitus.
Side under examination against the detector.
Interpupillary line perpendicular to the detector (avoid lateral tilt).
Midsagittal plane parallel to the detector.
Central ray: perpendicular, centred 5 cm above and anterior to the EAM.
5 cm superior to the EAM (external auditory meatus)
70–80 kV · 10–15 mAs
SID ~100 cm · grid
70–80 kV · 15–25 mAs · SID ~100 cm
Skull in lateral profile: inner and outer tables superimposed (or minimal double image).
Sella turcica in profile with anterior and posterior clinoid processes visible.
Frontal and sphenoidal sinuses in profile.
Petrous ridges superimposed (confirms no rotation).
Mandible superimposed.
Calvaria included.
Head rotation (petrous ridges not superimposed).
Lateral head tilt.
Incorrect centring (sella turcica outside field).
Movement.
Sella turcica normal dimensions on lateral: anteroposterior diameter 5–16 mm, depth 4–12 mm. An expanded sella (> 16 mm AP) may indicate a pituitary adenoma — report to the radiologist.
In head trauma the lateral complements the PA for vault fracture assessment (linear or depressed) and posterior cranial fossa evaluation.
Paediatric patient: kVp reduced by 10–15%, mAs ÷2–3. Open fontanelles and sutures in infants are normal and must not be mistaken for depressed fractures. Sutures visible until age 2–3 years. Lateral support for immobilisation.