DR is based on the X-ray television system, the use of computer digital processing, so that the analog video signal after sampling, analog / digital conversion (analog to digit, A/D) directly into the computer for storage, analysis and preservation. x-ray digital image of high spatial resolution, dynamic range, its image can be observed with a contrast ratio of less than 1%, the diameter of the object is greater than 2MM, in the patient's digital image, the image can be viewed in the patient, the image can be viewed in the patient's digital image, the image can be viewed in the patient's digital image. With high spatial resolution and large dynamic range, X-ray digital images can observe objects with a contrast ratio of less than 1% and a diameter of more than 2MM, and the surface X-ray dose measured on the patient is only 1/10 of that measured by conventional photography. the quantum efficacy (DQE) can be up to 60% or more. the digitization of the X-ray information can be processed by computers. By improving the details of the image, reducing image noise, gray scale, contrast adjustment, image magnification, digital subtraction, etc., to show the characteristics of the unprocessed image can not be seen in the information. Computer-aided diagnosis can be performed by quantitative analysis and feature extraction of images with the help of artificial intelligence and other technologies. Digital radiography includes selenium cartridge, direct digital radiography (direct digital radiography; DDR), charge coupled device (charge coupled device; CCD) camera array and other methods. The digital image has a high resolution, good image sharpness, details show clearly; radiation dose is small, the exposure tolerance is large, and according to the clinical needs of a variety of image post-processing and other advantages, but also to realize the radiology department without film, between departments, hospitals, networked, and easy to teach and consultation.