PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of reconstructing a tomographic image which reduces the occurrence of artifacts and shows information on the distribution of atoms constituting a subject.SOLUTION: The X-ray CT apparatus includes: an X-ray data acquisition means which acquires projection data of X rays transmitting through the subject between an X-ray generating device for emitting X rays and an X-ray detector opposed to the X-ray generating device for detecting the X rays while rotating them about the center of the rotation in a position between them and an image reconstructing means for reconstructing an image of the projection data acquired from the X-ray data acquisition means. The X-ray data acquisition means includes a means which emits X rays by sequentially switching a plurality of X-ray tube voltages and acquires X-ray projection data acquired by the irradiation of X rays of each X-ray tube voltage. The image reconstructing means includes a means which performs correction processing depending on two kinds of X-ray tube voltages before and after the switching for an interval of the changeover between the plurality of X-ray tube voltages.COPYRIGHT: (C)2008,JPO&INPIT【課題】アーチファクトの発生を低減した、被検体を構成する原子の分布情報を表わす断層像を画像再構成できるX線CT装置を提供する。【解決手段】X線を照射するX線発生装置と、相対してX線を検出するX線検出器とを、その間にある回転中心のまわりに回転運動させながら、その間にある被検体を透過したX線投影データを収集するX線データ収集手段と、そのX線データ収集手段から収集された投影データを画像再構成する画像再構成手段とを含むX線CT装置において、前記X線データ収集手段は、複数のX線管電圧を順次切り替えてX線を照射し、それぞれのX線管電圧のX線照射によって得られるX線投影データを収集する手段を含み、前記画像再構成手段は、前記複数のX線管電圧の切り替え区間について、切り替え前後の2種類のX線管電圧に依存した補正処理を行う手段と含む。【選択図】図7
