1. A method for removing ring artifacts from tomograms produced with the aid of a computed tomography unit including at least one recording system rotating about a rotation axis, the method comprising: reconstructing N tomograms I k (k=1,. .. , N) at recording positions that are substantially equidistant in the direction of the rotation axis; calculating a temporary ring artifact image Rt k for each tomogram I k which has at least one ring artifact present in the respective tomogram I k ; calculating a ring artifact image R k for each tomogram I k , the respective ring artifact image R k being formed by averaging over at least a portion T sub of the temporary ring artifact images Rt k , and the temporary ring artifact images Rt k being rotated before averaging in such a way that the ring artifacts present in the temporary artifact images Rt k substantially coincide and their position substantially corresponds to the ring artifacts present in the tomogram I k ; and subtracting the respective ring artifact image R k from the respective tomogram I k , in each case one result image E k being produced in which the ring artifact is removed.