To reduce the computational load in comparison to the iso-center shift described above, instead of selecting the z-axis of the coordinate system as the iso-center for reconstruction, the gantry iso-center of one of the detector rows (e.g., one of the center rows) is selected as the reconstruction iso-center. In this arrangement, the detector row for which the iso-center is based need not to undergo protection shift, since the defined reconstruction iso-center is the row iso-center. Data from the other detector rows is shifted relative to the selected detector row. When the gantry iso-center of one of the detector rows (e.g., one of the center rows) is selected as the reconstruction iso-center, the reconstructed image will be shifted along y′-axis relative to the original compensation schemes described above. To ensure the images generated with both schemes are identical in location, an adjustment can be added in the backprojection process.