Photodiode (PD) chip is used for light detection in the X-ray detector. It is one of the important components in the X-ray detector system by converting the visible light emitted by the scintillator into electrical signals for output, so as to obtain the image containing the information of the detected object. PD chips are usually made of monocrystalline silicon materials. Through the semiconductor process, the pixel detection area is formed, and has low leakage current and junction capacitance, and has high light response to wide visible light spectrum. PD chips include different design size, from one-dimensional linear array to two-dimensional plane array, pixel sizes include 0.4mm, 0.8mm, 1.2mm, 1.6mm, 2.5mm, 4.6mm and other specifications, and can be customized according to needs. PD chips include two types: front-side illumination (FSI) and back-side illumination (BSI), which can be selected according to different applications. The detector module is formed through the packaging process with scintillator, which has a wide range of applications in radiation detection and imaging fields such as security, food detection, industrial detection, security CT, medical CT, etc.