Patent ID: 7529346
Filing Date: 2009-05-05
Classification: H01J,H05G

Abstract:
1. A method for stabilizing the size of a focal spot of an X-ray tube, the method comprising: providing the tube with a cathode comprising a concentrator and a heating filament; placing an anode to face the cathode; bombarding the anode on a surface thereof called a focal spot with an electron beam produced with the heating filament; applying a bias voltage between a terminal of the filament and a terminal of the concentrator; measuring a size of the focal spot; measuring a function of contrast modulation of an image produced; regulating the size of the measured focal spot by comparing the measured focal spot to focal spot set values and adjusting the bias voltage accordingly; and regulating the measured contrast modulation function by comparing the measured contrast modulation function to contrast modulation function set values and adjusting the bias voltage accordingly.