Maxillary Sinuses
Parietocanthial (Waters) IR Size: 8x10 LW SID: 40"" Page #'s: 2:374,320	Positioning:   • Pt seated or upright   • Chin rests on grid & Nose should be ~3/4"" from grid   • If neck extended to much-maxillary sinuses foreshortened & antral floors not shown obscuring pathology   • If neck not extended enough-petrosae projected over inferior part of maxillary sinuses	CR Entrance & Angle:   • _|_ to exit acanthion   • Collimation:   • Best to Determine:   • Primary-Maxillary & also shows Frontal   • Also shows foramen rotundum	Eval Criteria:   • NR by Equidistant lat borders of skull & orbits   • Petrous ridges just below maxillary sinuses   • Orbits and maxillary sinuses symmetric on each side