The working principle of CR: the first step, X-ray exposure so that the IP image plate image latent shadow; the second step, the IP plate into the laser scanner for scanning, in the scanner IP plate latent shadow is excited into visible light, read and then converted into electronic signals, transmitted to the computer will be displayed on the digital image, but also print out the diagnostic requirements of the laser photo, or stored in the tape. disk and CD-ROM storage, The structure of CR system is relatively simple and easy to install; IP image board can be applied to existing X-ray machines, directly realizing the digitization of general radiological equipment, improving work efficiency and bringing great social and economic benefits to hospitals. It is safer to reduce the patient's dose of irradiation; CR's display of bone structure, articular cartilage and soft tissue is significantly better than that of traditional X-ray imaging; it is easy to display mediastinal structures such as blood vessels and trachea; the detection rate of nodular lesions in lungs is higher than that of traditional X-ray imaging; CR (Digital Radiographic Imaging Board) is superior to that of traditional X-ray imaging in the observation of calcium-containing lesions such as intestinal pneumatosis, pneumomediastinum and calculus; it can be used for double-contrast gastrointestinal contrast imaging in the display of gastric microcellulites, microscopic lesions and intestinal mucosal folds. CR (Digital Gastrointestinal) is superior to conventional X-ray images in the visualization of gastric cells, microscopic lesions and intestinal mucosal folds. DR (Digital Radiography), digital radiography, the system consists of a digital image acquisition board (detector board, Flat Pannel Dector, on its internal structure can be divided into CCD, amorphous silicon, amorphous selenium several kinds), special filters BUCKY digital image acquisition control X-ray photographic system digital image workstations. Its working principle is in the amorphous silicon image board, X-ray by the fluorescent screen into visible light, and then by the TFT thin-film crystal circuitry according to the matrix pixels into electronic signals, transmitted to the computer, the image will be displayed through the monitor, but also can be transmitted into the PACS network. DR technology can be divided into non-direct conversion from the X-ray detector imaging principle and direct conversion of the two categories. The first generation of non-direct conversion using a sensing screen plus optical lens coupled to the CCD (charge coupled device) to obtain digital X-ray images. The second generation is the use of direct conversion technology, i.e., flat panel detector. x-ray digital image of high spatial resolution, dynamic range, its image can observe the contrast is less than 1%, the diameter of the object is greater than 2MM, in the patient's body measured to the surface of the x-ray dose is only 1/10 of the conventional photographic. x-ray information digitization can be processed by the computer. By improving the details of the image, reducing the image noise, gray scale, contrast adjustment, image magnification, digital subtraction, etc., it shows the characteristic information that cannot be seen in the unprocessed image. With the help of artificial intelligence and other technologies for quantitative analysis of images and feature extraction, computer-aided diagnosis can be carried out.