Principle of amorphous selenium flat plate detector:
1. X-ray incident photon excites electron-hole pair in amorphous selenium layer;
2. Electrons and holes move in reverse under the action of the applied electric field, generating an electric current, whose magnitude is proportional to the number of incident X-ray photons;
3. These current signals are stored in inter-electrode capacitors of TFT, each of which forms a pixel unit.
Advantages of amorphous selenium flat plate detector: 1. High conversion efficiency, wide dynamic range; 2.2. High spatial efficiency;3. Good sharpness;
Disadvantages of amorphous selenium flat plate detector: 1. Low X-ray absorption rate, image quality can not be well guaranteed under low dose conditions, while increasing X-ray dose, not only increases the absorption of disease sources, but also requires too much of the X-ray system.
2. The selenium layer is sensitive to temperature, limited use conditions and poor environmental adaptability.