Patient position
Erect or prone for PA; supine for Towne's; semi-prone for axiolaterals.
Part position
PA: forehead and nose on IR, OML perpendicular. Axiolateral: head true lateral, then rotated 30° toward IR.
Central ray
PA: perpendicular to acanthion. Towne's: 35° caudal to glabella. Axiolateral: 25° cephalic to mandibular angle.
IR placement
24x30 cm; divided for axiolaterals.