Abstract: A method for vacuum depositing a selenium-arsenic coating on a substrate to form a photoreceptor by evaporating selenium with an arsenic concentration of 0.1 to 0.6 percent by weight and discontinuing the evaporation when the weight of the selenium alloy remaining is 2-10 percent of the original weight.

Abstract: A plastic bite holder for securely holding a rigid cassette comprising a photoreceptor and a light proof cover for use as a dental x-ray imaging medium is described. The holder is molded into a single piece of polyethylene and has a tab onto which the patient bites, a backing plate and two gripping members for securely holding the cassette against the backing plate.

Abstract: This invention is a plastic holder for holding a rigid photoreceptor in the mouth during the creation of dental bitewing and periapical x-ray images, and more particularly is a one-piece plastic holder comprising (1) a bitewing holder comprising a backing plate, a tab and two gripping members for holding the photoreceptor in secure contact with the backing plate, (2) a periapical holder comprising a backing plate and a gripping member for holding the photoreceptor in secure contact with the backing plate, and (3) a handle in the form of a plastic strip connecting the two holders.