tion. In at least one example embodiment of the computer-implemented method, calculating the filtered back-projection density distribution from the filtered 0D projections by way of filtered back-projection comprises: determining, for each volume position in the reconstruction volume and for each 0D projection, two-dimensional in-plane coordinates by projecting the volume positions onto the projection plane defined by each of the 0D projections; determining, for each volume position in the reconstruction volume and for each 0D projection, a weighted contribution of each of the filtered 0D projections, wherein determining the weighted contributions includes evaluating the filtered 0D projections at the in-plane coordinates corresponding to the volume position; calculating a filtered back-projection density distribution from the filtered 0D projections by accumulating the weighted contributions of the 0D projections corresponding to different projection planes. 