?Digital flat-panel direct imaging technology (DR) is a new digital imaging technology developed in recent years. Its features such as clear and exquisite images, high resolution, wide grey scale, large amount of information and dynamic range, are conducive to improving the accuracy of defect assessment. ?Unlike film and CR processing, there is no need to replace the film or store the fluorescent plate during two diaphanous imaging. ?It takes only a few seconds for data to be collected and images can be observed, with detection speed and efficiency much higher than film and CR techniques. ?The imaging quality of the digital flat plate is much better than that of the real-time imaging system of image intensifier. Not only is the imaging area uniform, no edge geometric deformation, but also the spatial resolution and sensitivity are much higher. Its image quality has approached or reached film photography level. ?In contrast to LDA line array scanning, a digital flat plate can make a large one exposure to form an image without moving or rotating the workpiece through multiple line scans. ?Plate detector is the core part of DR, and its characteristics will have a relatively large impact on the image quality of DR.