CR(ComputedRadiography) is also known as indirect digital X-ray imaging technology, and its main principle is to use stored phosphor to image. Fuji Company of Japan introduced the first CR for clinical application in 1981, and then Kodak Company of the United States and AGFA Company of Germany successively introduced their own CR products. It uses an imaging plate made of phosphor crystals, that is, an IP plate, to absorb X-ray information, and the IP plate is exposed to light to form a latent image, which is then scanned. The IP board looks like an ordinary intensifying screen, which is composed of a substrate and phosphor materials. The working principle of R, DR(Digitalradiography), is also called digital photography. In the early days, DR used a CCD (digital coupler) coupled with an intensifying screen and an optical lens to obtain digital X-ray images, which is somewhat similar to the working method of an image intensifier and CCD. This technology is considered as the first generation of DR technology.