When evaluating an image of the sinuses, which projection has been performed if the frontal sinuses are lying above the frontonasal suture?

The posteroanterior (PA) axial projection, specifically the Caldwell method, is commonly used to visualize the frontal sinuses. In this projection, the patient's forehead and nose are placed in contact with the imaging receptor, and the X-ray beam is angled downward towards the eyes. This set-up allows for a clear view of the frontal sinuses, situated just above the frontonasal suture.

In this orientation, when the frontal sinuses appear above the frontonasal suture, it indicates the correct alignment and projection have been used to obtain this desired visualization. The structure of the skull in the PA axial view emphasizes the relationships of the sinuses to the surrounding anatomical landmarks.

The other imaging projections do not provide the same clarity concerning the positioning of the frontal sinuses in relation to the frontonasal suture. For instance, a lateral projection displays the sinuses in a side view, which may obscure the frontal sinus location relative to the frontonasal suture. Similarly, the submentovertex projection primarily focuses on the base of the skull and mandible, while the anteroposterior projection is generally less precise for evaluating sinus anatomy in this region. Thus, the PA axial projection offers the best orientation for this specific