Focal spot size stabilizing method for x-ray tube, involves applying bias voltage between filament and concentration part terminals, measuring spot size and contrast modulation function, and adjusting spot size and function using voltage

摘要

The method involves providing a x-ray tube (1) with a cathode (2) including a concentration part (5) and a filament (2a), and placing an anode (3) opposite to the cathode. An electron beam (8) bombarding the anode in a surface of a focal spot (9) is produced with the filament. A bias voltage is applied between a filament terminal and a concentration part terminal. A size of the focal spot and a contrast modulation function are measured. The size of the spot and the modulation function are adjusted using the bias voltage. An independent claim is also included for a x-ray tube comprising a cathode.