Method for influencing a position of a focal spot in an x-ray radiation source of a computed tomography apparatus, and computed tomography apparatus

摘要

A method for adjusting a position of a focus spot 10 in an x-ray radiation source 2 of a computed tomography apparatus 1 is disclosed. The x-ray radiation source has at least one centering unit 7 for centering an electron beam. A reference object 13 is positioned in a beam path between the x-ray radiation source and an x-ray radiation detector 12. X-ray images of the reference object is captured at different x-ray powers (equal to the electron acceleration voltage Ua multiplied by the cathode current IK). The x-ray images at different powers are compared and a focal spot displacement is reduced based on the comparison by setting or altering at least one electric current for operating the centering unit. A look up table may be used to estimate the extent to which the electric current needs to be changed for a given displacement. The altered electric current is subsequently used for operating the computed tomography apparatus.