What does a 40-degree cephalad central ray directed through the plantar surface of the foot result in?

When a 40-degree cephalad central ray is directed through the plantar surface of the foot, the resulting image produces an axial projection of the calcaneus, which is the heel bone. This angling of the central ray helps in visualizing the posterior structures of the foot with clarity, allowing for better evaluation of the calcaneus itself.

In the case of imaging the calcaneus, a cephalad angle enables the central ray to pass through the heel bone in such a way that it minimizes superimposition from surrounding structures. The axial projection is particularly useful for diagnosing fractures or other conditions affecting the calcaneus, as it offers a detailed view of the bone and its articulation with adjacent bones.

This specific angulation and direction is crucial for obtaining the best diagnostic image, emphasizing the anatomy of the calcaneus while reducing distortion and overlap from other bony structures in the foot.