Which surface of the ankle is placed in contact with the IR for the upright lateral projection?

In the upright lateral projection of the ankle, the lateral surface of the ankle is the one that should be placed in contact with the image receptor (IR). This positioning is crucial as it allows for clear visualization of the anatomical structures of the ankle joint, including the tibia, fibula, and the tarsal bones.

Positioning the lateral surface against the IR ensures that the image is captured in a way that accurately represents the anatomy in profile, which is important for diagnosing any potential injuries or conditions affecting the ankle. In the lateral view, the relationship between the bones and the joint spaces is best demonstrated, allowing for a comprehensive evaluation.

Other surfaces, such as the medial, posterior, or anterior surfaces, do not provide the same clarity or alignment for the anatomical structures when capturing a lateral image of the ankle. Hence, placing the lateral surface in contact with the IR is essential to achieve the desired imaging results.