Final answer:
In a Caldwell view radiograph of the skull, rotation is assessed by ensuring that the lateral borders of the orbits are equidistant from the midline and that the petrous ridges project into the lower third of the orbits.
Step-by-step explanation:
Rotation assessment on a Caldwell view of the skull is crucial to examining the proper alignment and positioning in radiographic imaging. The Caldwell view is an X-ray projection that focuses on the frontal sinuses, the orbit, and the anterior ethmoidal air cells, so it has significant value in identifying fractures or other pathologies. To assess rotation, one must ensure that the lateral borders of the orbits are equidistant from the midline of the skull on the image, and the petrous ridges should project into the lower third of the orbits. If either of these criteria is not met, it suggests that there has been rotation, which could result in a diagnostic oversight.