A poorly positioned parietoacanthial facial bone projection (Waters method) demonstrates the petrous ridges within the maxillary sinuses. How was the positioning setup mispositioned for such a projection to be obtained?
1)The MML was not aligned perpendicular to the IR.
2)The patient's head was rotated toward the left side.
3)The patient's chin was tucked more than needed.
4)The central ray was angled too cephalically.
A) 1 and 3 only
B) 2 only
C) 3 and 4 only
D) 1, 3, and 4 only

Question

Quizplus · Accepted Answer

1) If the MML is not aligned perpendicular to the IR, the resulting image will show elongation or foreshortening of the facial bones. This can cause the petrous ridges to be superimposed over the maxillary sinuses.
3) If the patient's chin is tucked more than needed, the angle between the MML and the IR will be decreased, resulting in a more horizontal beam angle. This can cause the petrous ridges to be superimposed over the maxillary sinuses.
4) If the central ray is angled too cephalically, the resulting image will show a greater degree of superimposition between the petrous ridges and the maxillary sinuses.

A Poorly Positioned Parietoacanthial Facial Bone Projection (Waters Method) Demonstrates