ABSTRACT
Image quality of the image intensifier system is affected by scintillation, resolution, contrast, and distortion. The image intensifier tube is an evacuated glass envelope, a vacuum tube, which contains four basic parts: Input phosphor and photocathode, Electrostatic focusing lens, Accelerating anode and Output phosphor. Field size on the output phosphor is changed by applying a simple electronic principle: the higher the voltage on the electrostatic focusing lens, the more the electron beam is focused. The brightness gain, or “intensification gain” as it was called, was expressed as the luminance of the output screen compared to the luminance of a standard Patterson fluoroscopic screen with the same incident radiation. It is important to understand that the flux gain is an inherent number that each individual image intensifier tube manufacturer will indicate. The automatic brightness stabilizer is that part of the fluoroscopic control system which keeps the light output of the image intensifier constant over variations of patient attenuation and system geometry.
