An axial plantodorsal projection for the calcaneus is performed with the central ray angled how many degrees to the surface of the IR?

The axial plantodorsal projection for the calcaneus is performed with the central ray angled 40 degrees to the surface of the image receptor (IR). This specific angle is crucial for properly visualizing the anatomy of the calcaneus (heel bone) without distortion while demonstrating the subtalar joint.

When the central ray is angled correctly, it allows for optimal projection of the calcaneus, providing a clear view of its structure. This technique helps radiologic technologists produce diagnostic images that allow for accurate assessment of potential injuries or pathologies related to the calcaneus. Angling the central ray too much or too little could result in foreshortening or elongation of the calcaneus, leading to suboptimal images that may miss important diagnostic information.