In what position should a patient be for a posteroanterior (PA) axial projection (Caldwell method)?

For a posteroanterior (PA) axial projection using the Caldwell method, the ideal position for the patient is to have them in a prone or seated position with their forehead resting against the imaging receptor or table. This positioning is critical for accurately obtaining the specific angles required for proper visualization of the cranial structures, particularly the orbits and frontal sinuses.

In the Caldwell method, the X-ray beam is angled caudally, which is best achieved when the patient's forehead is against the detector. This setup ensures that the radiographer can effectively center the beam and capture the desired anatomical details without distortion. The forehead's direct contact with the table or receptor also helps to stabilize the position, reducing motion blur in the image.

This projection is designed to create an image with the central ray directed at the nasion, optimizing the clarity of the frontal and occipital regions while minimizing overlaps of the anatomical structures.