What angulation is used for the central ray in a calcaneal axial radiograph?

• A. 40 degrees cephalad to long axis of foot
• B. 10 degrees caudad
• C. 90 degrees to long axis
• D. 60 degrees cephalad

Answer: (A)

When aiming to get an axial view of the calcaneus, the central ray is positioned so it travels along the long axis of the bone. The standard approach is to angle the beam about 40 degrees toward the head (cephalad) relative to the long axis of the foot. This alignment projects the calcaneus axially, reducing overlap with the talus and allowing a clear view of the posterior facet and subtalar joint. It also helps prevent distortion and magnification of the calcaneal structures that would occur if the beam were too shallow or too steep.

Angles markedly different from this, such as a small tilt like 10 degrees cephalad, would not align with the calcaneal axis and can blur or obscure the important subtalar joint details. A steeper tilt, around 60 degrees cephalad, increases distortion and can shift the anatomy out of proportion. A 90-degree orientation would not yield the intended axial projection and would look more like a different view, losing the specific perspective needed for the axial calcaneus.