Automatic calibration systems.

摘要

A voltage control (22) controls the voltage applied between an anode (12) and a cathode filament (14) of an x-ray tube (10). A filament control (16) controls the amount of current fed through the filament. A voltage controlled oscillator (42) and counter (44) monitor the magnitude of a tube current (24) flowing between the cathode and the anode to generate x-rays (26). A microprocessor (50) calibrates the filament current such that the filament current value stored in a filament current look-up table (122) for each selectable tube voltage and tube current combination actually produces the selected tube current. The filament current is set (60) to a small current value and progressively incremented (66) until a tube current (24) is monitored (64). To calibrate each selectable tube voltage, tube current combination, the filament current is incremented from this initial current flow or emission point (52) and the resultant tube current is compared (98) with the selected tube current. A substantial portion of the filament current values stored in the filament current look-up table are determined in this way and the rest are determined by interpolation (140). <IMAGE>