In the dorsal plantar axial projection of the calcaneus, the CR should be directed how many degrees and in what direction to the plantar surface?

• A. 20° cephalad
• B. 30° caudal
• C. 40° caudal
• D. 50° cephalad

Answer: (C)

In the dorsal plantar axial projection of the calcaneus, the central ray (CR) is directed at an angle of 40 degrees caudal to the plantar surface of the foot. This specific angle is essential because it allows for the optimal visualization of the calcaneus, particularly the subtalar joint and the superior aspect of the heel bone.

By angling the CR caudally, it helps reduce the superimposition of the surrounding structures, which is crucial for accurate diagnosis. If the angle is too shallow or too steep, the resulting image may distort the anatomy or fail to capture the area of interest properly. In this projection, achieving the correct angle is critical to ensure that the calcaneus is well visualized in relation to the other tarsal bones. Thus, the choice indicating a 40-degree caudal angulation is the appropriate technique for this imaging view.