A computed tomography apparatus and a method for influencing a position of a focal spot in an x-ray radiation source having a centering device to center an electron beam and a focus are provided. The method includes positioning a reference object into a beam path of x-ray radiation between the x-ray radiation source and an x-ray radiation detector, the x-ray radiation detector having detector elements to generate an x-ray image, capturing an x-ray image of the reference object at different powers, reducing a focal spot displacement occurring at the different powers based on a comparison of the x-ray images captured at the different powers with one another, by setting at least one altered electric current to operate the centering device or the centering devices of the x-ray radiation source, and operating the computed tomography apparatus with the altered electric current, by which the focal spot displacement was reduced.
