The invention relates to off-center detector X-ray tomography reconstruction of an image of an object on the basis of projection data acquired during a rotation of an X-ray source and the off-center detector around the object in two rotational passes of less than 360°, wherein a focus point of the X-ray beam travels along largely overlapping arcs (401, 402) in the two rotational passes, the off-center detector being positioned asymmetrically with respect to a central of the X-ray beam and a direction of a detector offset being reversed between the passes. According to the invention, redundancy weighting of the projection data with respect to a redundant acquisition of projection values during each of the rotational passes is made using a redundancy weighting function determined on the basis of a union of the arcs (401, 402).