Click here to return to the home page. 

As an X-ray tube is used, the operating voltage creeps up, until the point is reached at which the high tension generator cannot supply sufficient voltage to get the tube to strike.. In addition, as the operating voltage rises, the image contrast falls, although the exposure time needed falls. Ideally, the densest structure in the image should be completely clear, on the film, while the thinnest area should be just a little below the maximum density that the film can demonstrate. The difference between maximum and minimum density will depend on the part of the body being radiographed. Some control over the tube operating voltage by heating the walls of the tube with a Bunsen Burner, to release some of the gas. This is a hazardous procedure, since the tube is fragile. One solution was to fit a tube-like extension to the body of the X-ray tube. Heating this extension is a bit safer heating up the bulb.