What is indicated if the right and left halves of the skull do not appear symmetric on a posteroanterior (PA) or (AP) projection of the skull?

When the right and left halves of the skull are not symmetric on a posteroanterior (PA) or anteroposterior (AP) projection, this indicates that the sagittal plane, which divides the body into left and right halves, is not properly aligned with the image receptor (IR). For an accurate symmetrical representation of the skull, the sagittal plane needs to be perpendicular to the IR. If it is not, distortions can occur that make one side of the skull appear larger or more prominent than the other, thus creating an asymmetrical image.

This misalignment can result from the patient's positioning, where they may be tilted or rotated, leading to the apparent disparity in symmetry. Correct positioning and adherence to established protocols ensure that the imaging technique captures the skull accurately.