A receptor positioning device for taking dental bitewing radiographs of a patient's teeth comprises a receptor holding member adapted to receive a receptor for exposing x-radiation from the x-ray machine and a collimation plate having a substantially flat surface for aligning with an x-ray machine. The collimation plate has a rectangular opening in its surface for passage of radiation from the x-ray machine to expose a receptor in the receptor holding member and a pair of handles extending away from the plate for positioning the device. The collimation plate is constructed of metal having a thickness of at least 0.075 in., preferably at least 0.100 in., to reduce the passage of radiation from the x-ray machine to the patient except at the plate opening. The device also includes an arm between the collimation plate and the receptor holding member, the arm including a biting surface for engaging the patient's teeth to secure the device in the patient's mouth, and an aiming ring secured to the arm at a position distal from the receptor holding member, with the collimation plate being secured to the aiming ring. The aiming ring may also include notches and the collimation plate preferably includes clips for removably securing the plate to the aiming ring and tabs for locating the plate relative to the aiming ring notches.