In the parietoacanthial projection, modified Waters method, of the facial bones, the orbitomeatal line forms what angle to the IR?

• A. 60 degrees
• B. 55 degrees
• C. 50 degrees
• D. 45 degrees

Answer: (B)

In this positioning question, the key idea is how the tilt of the head relative to the image receptor affects the parietoacanthial view of the facial bones. For the modified Waters method, the orbitomeatal line is placed so that it forms about 55 degrees with the plane of the image receptor. That specific tilt brings the facial structures into the correct orientation to minimize distortion, open up the paranasal sinuses (especially the maxillaries), and reduce overlap of the orbital rims. It’s a different setup from the standard Waters, which uses a smaller tilt, and this larger 55-degree angle is chosen to optimize visualization in the modified technique. If the tilt were noticeably less, structures would be more overlapped and sinuses less clearly demonstrated; if it were more, the anatomy would become distorted due to over-rotation.