[Tomography of the pterygoid canals]

This paper presents an X-ray scheme for calculating the depth of pterygoid canals required for accurate tomography. The scheme includes three lines: line A corresponds to the physiological horizontal line, line B is drawn, normally to line A through the tip of the nose, and line C is the perpendicular from line B to the upper third of the posterior wall of the pterygopalatine fossa. The length of line B plus 1 cm (thickness of external nose soft tissues) is the value to be determined. Twenty-six patients underwent X-ray examinations by an EDK-750B unit (70 kV, 150 mA, 1.65 s). In all cases 1-3 images were sufficient to obtain good visualization of the pterygoid canals.