Maxillary & Sphenoid Sinuses
Parietocanthial (Open-Mouth Waters) IR Size: 8x10 LW SID: 40"" Page #'s: 2:376,320	Positioning:   • Same Pos as Waters but mouth open   • Pt seated or upright   • Chin rests on grid & Nose should be ~3/4"" from grid	CR Entrance & Angle:   • _|_ to exit acanthion   • Collimation:   • Best to Determine:   • Primary-Sphenoidal & also shows Maxillary   • This and lateral may be only ones to show sphenoidal sinuses thru open mouth	Eval Criteria:   • NR by Equidistant lat borders of skull & orbits   • Petrous ridges just below maxillary sinuses   • Orbits and maxillary sinuses symmetric on each side   • Sphenoidal sinuses projected through the open mouth