Abstract: Apparatus for positioning an image receptor, such as X-ray film, within a patient's mouth in predetermined relation to an energy beam, such as an X-ray beam, generated externally of the patient's mouth, includes rigid structure supporting an image receptor and connecting it to the source of the energy beam, and a bite block removably attached to the rigid structure in a position such that the portion of the patient's maxilla and mandible gripping the bite block is removed from the portion being studied with the energy beam. The attachment system further provides for attachment of the bite block at any of a plurality of discrete sites relative to the image receptor. Bite registration material is preferably provided on the bite block surfaces to allow precise repositioning of the bite block in a series of successive exposures. The apparatus allows a plurality of target areas to be studied using one bite block position within the patient's mouth.