X-ray tube assemblies

摘要

An x-ray tube assembly includes an anode (A) and an envelope (C). A cathode assembly (B) including a cathode (12), which is supported in the envelope on a bearing (32), emits a beam of electrons which strike the anode forming a focal spot (14). The anode rotates relative to the cathode such that focal spot follows a generally annular path along an annular face (16) of the anode. If the axis of the anode and the cathode assembly are screwed or offset, the focal spot path is not circular and wobbles. An adjustment assembly (60) allows adjustment of the relative positions of the anode, the cathode and the envelope to adjust the anode and cathode assembly axes. Another adjustment assembly including one or more electrodes (102, 108) adjusts the position of the focal spot. A control circuit (110) applies an electrostatic potential to the electrodes to move the focal spot such that it stays on a constant plane of the annular face of the anode.An angular position encoder (106) identifies the angular orientation of the anode.