The changing process of image intensifier function structure

The image intensifiers currently used in most hospitals are the first generation of image conversion equipment for bright room fluoroscopy, X-ray dose reduction and compartment operations. From the appearance, the image intensifier is a large glass tube with a black dressing on the surface as a light sealing layer, and a high vacuum is maintained in the tube.
There is an input screen with a large area at the front end of the tube, and a layer of phosphor is coated on the input screen. The thicker the phosphor layer, the stronger the brightness, but this will reduce the resolution due to light scattering and reflection; the thinner the phosphor layer, the higher the resolution, but the brightness is reduced. In order to solve this contradiction, in recent years, new image intensifiers have adopted a relatively high atomic number cesium iodide phosphor input screen. Compared with the zinc cadmium sulfide phosphors used earlier, cesium iodide phosphors have the advantages of high X-ray absorptivity, high fluorescence efficiency, high image resolution and good matching with the photocathode spectrum. Like ordinary fluoroscopic screens, this screen absorbs X-ray photons with image information to produce visible fluorescent images.
Close to the input screen is the photocathode (there is a thin transparent layer between the two); the antimony-cesium type photocathode, when the photon of the phosphor image of the input screen irradiates the photocathode surface, the other side emits photoelectrons to form Electronic image, complete the photo-electric conversion process.

Author:Lillian