Figure 1-23.Ala-tragus line parallel with the floor.
Figure 1-24.Line from the corner of the mouth to the tragus parallel with the floor.
When the tube head has been set for the proper
vertical angulation, center the tube head cylinder on
the area to be radiographed. The cylinder should
almost touch the surface of the patient's skin. Then,
position the tube head for correct horizontal
HORIZONTAL ANGULATION.This is the
side-to-side positioning of the tube head. Position the
tube head so the central X-ray beam is directed straight
through the embrasures of the teeth being
radiographed. If the horizontal angulation is faulty, the
central ray will be directed at an angle to the
embrasures. This will produce a faulty radiograph,
with the images of the teeth overlapping one another.
Figure 1-29 illustrates the correct and incorrect