Skull/SinusesFull access
Sinus series
Always erect with a horizontal beam: lateral, Caldwell, Waters and SMV; open-mouth Waters for the sphenoid.
Why erect
Sinus views are always taken erect with a horizontal CR, so any fluid in a sinus lies flat and makes a visible air-fluid level. A supine or angled-beam image can hide the fluid. If the patient cannot sit up, a horizontal-beam view, such as a cross-table lateral, still shows a fluid level. The routine series is a lateral, a PA axial (Caldwell), a parietoacanthial (Waters) and often a submentovertical (SMV). Remove glasses, earrings, hair clips and dentures first.