PROBLEM TO BE SOLVED: To perform image reconstitution by an OS reconstitution method in high calculation efficiency on the basis of two pairs of data sets having view numbers different from each other.SOLUTION: An X-ray source 13 generates X-rays. A third generation detector 15 detects X-rays from the X-ray source 13, and acquires energy integral data on a first view number. A fourth generation detector 25 detects X-rays from the X-ray source 13 and acquires spectrum data on a second view number. A fourth generation detector 25 detects the X-rays from the X-ray source 13, and acquires spectrum data on the second view number smaller than the first view number. A pre-processing part 351 divides the energy integral data into a plurality of subsets, binds the spectrum data to each of the plurality of subsets and generates a plurality of bound subsets. A reconstitution calculation part 353 reconstitutes CT images by subjecting the plurality of bound subsets to OS reconstitution.
X-RAY COMPUTER TOMOGRAPHY APPARATUS AND IMAGE RECONSTITUTION METHOD