For the parietoacanthial projection (Waters) of the sinuses, the orbitomeatal line forms an angle of how many degrees with the image receptor (IR)?

In the parietoacanthial projection, commonly known as the Waters view, the orbitomeatal line (OML) is adjusted to form an angle of 37 degrees with the image receptor (IR). This specific angle is critical for obtaining a true Waters projection, as it ensures that the maxillary sinuses are optimally visualized.

The positioning at this angle allows for the best demonstration of the anatomic structures of the sinuses, particularly the maxillary sinuses, while minimizing any distortion. The 37-degree angle is a standard position in radiographic practice that provides a clear view of these important sinus regions. Proper alignment of the OML in relation to the IR is essential for producing accurate and diagnostic images in sinus imaging. In contrast, the other angles mentioned do not establish the correct orientation needed for this specific view.