C7921 is a newly developed digital X-ray image sensor for non-destructive inspection, biomedical imaging, X-ray microscopy, and other real-time X-ray imaging applications requiring high resolution and high image quality. It consists of a sensor board and a control board, assembled in a thin, flat, and compact package. The sensor board contains a CsI scintillator plate, a two-dimensional photodiode array with FET switches, and a signal processing IC chip. The photodiode array has a 1056 × 1056 pixel format with minimized blooming and is highly sensitive to bluish green light emitted from the CsI scintillator. Each row of pixels is addressed in sequence by the vertical shift register connected to the gate line. Light emission occurs when X-rays are absorbed in the CsI scintillator. This light emission enters directly into the two-dimensional photodiode array where an electric charge is stored in each pixel according to the light intensity. This charge is then transferred to the corresponding data line by applying a control signal to the vertical shift register. The sensor board also has 8 charge-sensitive amplifier arrays, each having 132 channel amplifiers with a horizontal shift register. These amplifiers, with a total of 1056 channels, are connected to a CDS (Correlated Double Sampling) circuit that senses the charge on each video line and sends it as the analog video signal from each amplifier array.
