Computed tomography system with control and correction of fan beam position.

摘要

A detector for detecting z-axis position in the plane of the fan beam of a computed tomography machine with respect to the detector array employs a pair of slotted masks over independent detector cells, the slots creating exposed widths that decrease and increase along their length. The intensity signals from the two detector cells so masked are subtracted to produce a z-axis position signal eliminating the effect of dark currents. Multiple cells may be ganged to reduce the eflects of sensitivity variations among pairs of detector cells. The z-axis position signal may be used to control the z-axis position of the fan beam with respect to the detector array and to reduce the effect of the detector cell's variation in sensitivity.