1. A method of reconstructing three-dimensional images from cone beam projection data of an object to be examined which is arranged in an examination zone, which method includes the steps of: (a) acquiring the cone beam projection data by means of an X-ray device which includes an X-ray source and an X-ray detector, the X-ray source being moved along a trajectory around the examination zone in order to acquire the projection data, (b) determining the contour of the sensitive detector surface of the X-ray detector on which the projection data was acquired, (c) determining pseudo-projection data in an overall outer zone, enclosing the sensitive detector surface in an annular fashion, from the projection data determined, and (d) reconstructing a three-dimensional image of the examination zone from the projection data acquired on the sensitive detector surface and from the pseudo-projection data determined in the outer zone.