A patient support apparatus includes a frame supporting a surface for a patient to lie on and an X-ray cassette mover coupled to the frame under the surface of the patient and adapted to receive an X-ray cassette. The patient support apparatus also includes one or more sensors located along the frame to sense a position of the patient on the surface and a controller in communication with the sensors and the X-ray cassette to determine the position of the patient on the surface and to position the X-ray cassette mover relative to the patient. The X-ray cassette mover provides a direct reference to the position of the X-ray cassette under the surface of the patient.
