Where should the central ray be directed for an AP ankle radiograph?

Where should the central ray be directed for an AP ankle radiograph?

• A. Over the malleoli
• B. Midway between malleoli
• C. Directly through the ankle joint
• D. 1 inch above the malleoli

Answer: (B)

Centering the beam midway between the malleoli and directing it perpendicular to the ankle joint places the ankle mortise and joint space at the center of the image. This gives a true projection of the ankle without distortion or unequal magnification of one side. If the ray were directed over a malleolus, the anatomy would be off-center, and the joint spaces could be distorted or clipped. If it were directed directly through the joint, you risk misalignment and unequal visualization if not perfectly centered, and if you aim 1 inch above the malleoli you’d miss the joint surfaces entirely. Centering between the malleoli provides the most consistent, diagnostic view of the ankle joint.

Centering the beam midway between the malleoli and directing it perpendicular to the ankle joint places the ankle mortise and joint space at the center of the image. This gives a true projection of the ankle without distortion or unequal magnification of one side. If the ray were directed over a malleolus, the anatomy would be off-center, and the joint spaces could be distorted or clipped. If it were directed directly through the joint, you risk misalignment and unequal visualization if not perfectly centered, and if you aim 1 inch above the malleoli you’d miss the joint surfaces entirely. Centering between the malleoli provides the most consistent, diagnostic view of the ankle joint.