Why is a cephalic angle of 10 degrees used for an anteroposterior (AP) projection of the foot?

The use of a cephalic angle of 10 degrees for an anteroposterior (AP) projection of the foot is essential to prevent foreshortening of the anatomy. When the x-ray beam is directed straight down onto the foot, especially in cases where the foot might be in slight extension or flexion, the structures can appear compressed or distorted. By angling the beam cephalically, the entire foot can be better visualized, allowing the true dimensions of the bones and soft tissues to be represented accurately on the radiograph. This angle diminishes the effects of the natural curvature of the foot and ensures that the depiction of the tarsals, metatarsals, and phalanges is as precise as possible, ultimately aiding in accurate diagnosis and assessment.