A computed tomography system is disclosed, along with a method and computer program product. An embodiment uses such a spiral acquisition to reconstruct a spatial three-dimensional image of the examination region. The method also includes establishing a topogram of the examination region by parallel projection of the image along a projection direction. An embodiment of the invention allows distortion-free acquisition of a topogram, as a reconstructed spatial three-dimensional image can simply be projected in a parallel manner along a projection direction. An embodiment also allows multiple topograms to be established easily with just one acquisition, in that the reconstructed image of the examination region is projected in a parallel manner along different directions. An embodiment of the invention also allows particularly fast acquisition of a topogram, in particular in the clinical environment, as the rotating part of the gantry does not have to be stopped for the spiral acquisition.