Where should the central ray be aimed for an AP ankle X-ray?

For an anteroposterior (AP) ankle X-ray, the central ray should be aimed through the ankle mortise joint, which is located proximal to the malleoli. This area is crucial as it provides a clear view of the joint space, allowing for the assessment of any potential fractures, dislocations, or other abnormalities involving the tibia, fibula, and the talus.

Positioning the central ray at the ankle mortise ensures that the X-ray captures the important anatomical structures in alignment, and provides a diagnostic image that reflects the true condition of the ankle joint. Proper positioning is essential for accurate diagnosis, which is why focusing on the correct anatomical landmark is critical in imaging practices.

Other options do not focus on the joint space necessary for an accurate representation of the ankle anatomy.