Variable gain X-ray image intensifier tube

An X-ray image intensifier tube with a variable gain SIT (silicon intensified target) target has been developed. The X-ray SIT tube has a gain control range of 300 to 1, low noise, 1500 TVL/ diameter limiting resolution, and picture quality comparable to that obtained with optically coupled X-ray intensifier-vidicon combinations. The variable internal gain of the X-ray SIT tube makes it possible to produce an electronic radiographic imaging system that can be used for both low-exposure-rate fluoroscopic examinations and high-exposure-rate, short-duration fluorographic recordings. Design considerations for the X-ray SIT target are presented, and a detailed analysis of the target noise is given. The measured characteristics of 6- and 9-in input diameter X-ray SIT tubes are summarized.