Detection system for x-ray tubes

摘要

A rotation monitoring system (70) detects the rotational speed of an anode (10) of an x-ray tube during use. The system (70) includes a detector (72), which detects a pulse of secondary x-rays generated by the interaction of a stream (C) of electrons with a known defect (83) on a surface (84) of the anode. The detector may be position inside or outside a vacuum envelope (14) of the x-ray tube. The stream of electrons is supplied by a secondary source (80), separate from a main source (18) of electrons used to generate the primary or working x-ray beam (B) of the x-ray tube. A single pulse is detected with each rotation of the anode, providing a simple method of calculation of the anode rotation speed. Preferably, a feed-back loop is used to correct the rotational speed of the anode so that overheating of the anode is avoided and the useful life of the x-ray tube is extended. <IMAGE>