X-ray collimation apparatus.

摘要

A computed tomography system corrects image errors resulting from misalignment of the fan beam (19,21,22) as a result of placement of the x-ray tube (26), thermal drift of the x-ray tube anode or mechanical stresses of the gantry or x-ray tube. Misalignment is determined alternately by means of a z-axis offset detector (30) which detects movement of the exposure area of the CT fan beam or a predictive model that calculates thermal drift or mechanical deflection of the focal spot of the x-ray tube based on previous use. The system includes a collimator (38,39,41) with a controllable x-axis position which may be controlled to reduce z-axis offset of the fan beam exposure area or to make the fan beam more parallel with the imaging plane of the CT system.