PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus that can obtain a high-precision CT image by a successive approximation reconfiguration method with a small amount of calculation.SOLUTION: The X-ray CT apparatus sequentially performs: a step for identifying at least two types of projection data of a subject from projection data detected by an X-ray detection unit a step for calculating a region including a predetermined subject among the at least two types of subjects from the identified projection data and a step for producing a CT image in the region including the predetermined subject.COPYRIGHT: (C)2013,JPO&INPIT【課題】少ない計算量で、逐次近似再構成手法により高精度なCT画像を得ることができるX線CT装置を提供する。【解決手段】X線検出部が検出した投影データから、少なくとも2種類の被写体の投影データを判別する処理と、判別した前記投影データから前記少なくとも2種類の被写体のうち所定の被写体を包含する領域を計算により求める処理と、所定の被写体を包含する領域内についてCT画像を生成する処理とを順に行う。【選択図】図4
