Which structure is centered by the beam on a lateral ankle radiograph?

• A. Medial malleolus
• B. Lateral malleolus
• C. Calcaneus
• D. Talus

Answer: (A)

Centering the beam over the medial malleolus places the central ray right through the ankle joint, producing a true lateral view with proper visualization of the ankle mortise and surrounding bones. The medial malleolus sits at the midline of the ankle joint, so directing the X-ray beam there minimizes distortion and ensures the distal tibia, distal fibula, and talus are captured in correct relationship. If the beam were centered over the lateral malleolus, calcaneus, or talus, the image would be off-center and the joint alignment could be unclear. This landmark provides a reliable, consistent center for assessing fractures or dislocations in the ankle from the lateral perspective.