The head is positioned so that the orbitomeatal line (OML) forms a 37-degree angle with the plane of the image receptor. Which projection is used?

The head is positioned so that the orbitomeatal line (OML) forms a 37-degree angle with the plane of the image receptor. Which projection is used?

• A. Parietoacanthial (Waters method)
• B. Acanthoparietal projection
• C. PA projection
• D. Lateral sinus

Answer: (A)

The orbital-meatal line forming about 37 degrees with the image receptor is the setup for the parietoacanthial (Waters) projection. In this position, the chin is raised so the OML makes this 37° angle to the IR, which places the petrous ridges below the maxillary sinuses and provides a clear view of the paranasal sinuses from the front. That orientation uniquely identifies the Waters method. The other options involve different head tilts or views (for example, a PA setup, a lateral view, or an acanthoparietal oblique) and would not have the OML at approximately 37 degrees to the IR.

The orbital-meatal line forming about 37 degrees with the image receptor is the setup for the parietoacanthial (Waters) projection. In this position, the chin is raised so the OML makes this 37° angle to the IR, which places the petrous ridges below the maxillary sinuses and provides a clear view of the paranasal sinuses from the front. That orientation uniquely identifies the Waters method. The other options involve different head tilts or views (for example, a PA setup, a lateral view, or an acanthoparietal oblique) and would not have the OML at approximately 37 degrees to the IR.