The description refers to a process for the reconstruction of an object, whereby the object is transilluminated by rays which emanate from a radiation source having a cone-shaped beam geometry and the attenuation of the rays is detected for various positions of the radiation source, and whereby the three-dimensional construction of the object is reconstructed by means of the Feldkamp algorithm. The process according to the process is characterized by the fact that the area lying inside the beam cone is parameterized in cylinder coordinates.