An image processing element 9 of the present invention includes a weighting factor setting element 9a that sets up a weighting factors wnn, wbi of the weight addition combing a nearest neighbor interpolation and a bilinear interpolation based on an absolute value |Ibi−Inn| of the difference between the pixel value Inn acquired by the nearest neighbor interpolation and the pixel value Ibi acquired by the bilinear interpolation; and a weight addition element 9b that implement a weighting addition based on the set-up weighting factors wnn, wbi. A reconstructed image can be acquired by arranging the backprojection pixel value Inew every pixel following the weighting. A reconstructed image can be obtained in which any noise and artifacts are reduced by setting the weighting factor of the image processing algorithm causing a negative effect on the region of some pixel values to be minimal and setting the weighting factor of the (other) image processing algorithm causing a positive-effect on the same pixel value region to be maximum based on the absolute value |Ibi−Inn| of the difference.