Procedures

AP stands for anteroposterior: the central ray enters the anterior (front) surface and exits the posterior (back) surface of the body part.

In a PA projection the central ray enters the posterior surface and exits the anterior surface of the body part.

A lateral projection is named for the side of the body closest to the image receptor; the central ray passes side to side in the coronal plane.

An oblique projection rotates the body or part so it is neither in a true frontal (AP/PA) nor a true lateral position; the central ray passes through the part along an oblique plane.

In an RPO position the patient's right posterior surface is rotated nearest the image receptor (rotated from supine toward the right back).