1. A method for generating a computed tomography image of a periodically moving organism of an organism, wherein the organ comprises a plurality of regions each having a rest phase and a movement phase, with the respective rest phases of different ones of said regions ensuing at different points in time, comprising the steps of: (a) emitting an x-ray beam from a focus of an x-ray source and rotating at least said focus around said organ to irradiate said organ from a plurality of different directions, and detecting x-rays in said x-ray beam attenuated by said organ at each of said directions, thereby obtaining a plurality of projections of said organ, during at least one rotation of said focus around said organ and during a duration that is at least equal to one period of the periodic movement of the organ, each of said projections comprising projection data; (b) analyzing said projection data to determine whether the projection data were acquired during a rest phase or during a movement phase of at least one of said regions of said organ; and (c) reconstructing an image of said organ using only projection data acquired during the respective rest phase of said at least one of said region of said organ.