PROBLEM TO BE SOLVED: To discriminate materials with high accuracy.SOLUTION: An X-ray CT apparatus includes an X-ray generator, an X-ray detector, a calculation unit, and a determination unit. The X-ray generator irradiates a subject with X-rays. The X-ray detector detects X-rays transmitted through the subject. The calculation unit calculates an irradiation spectrum as a spectrum up to reaching at the subject, and an estimated spectrum estimated as a spectrum after the X-rays transmit through the subject on the basis of an estimated distance showing an estimated value of an X-ray transmission distance of a material to be discriminated, and information showing distortion of the spectrum caused in a path of the X-rays transmitted through the subject, among spectra showing distribution of photon counts for each energy of the X-rays. The determination unit determines an X-ray transmission distance of the material to be discriminated, on the basis of the estimated spectrum and a detected spectrum, which is a spectrum after transmitting through the subject detected by the X-ray detection unit.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2017,JPO&INPIT【課題】高精度に物質弁別を行う。【解決手段】実施形態に係るX線CT装置は、X線発生器と、X線検出器と、演算部と、特定部とを備える。X線発生器は、被検体に対してX線を照射する。X線検出器は、前記被検体を透過したX線を検出する。演算部は、前記X線のエネルギー毎の光子カウント数の分布を示すスペクトルの内、前記被検体に到達するまでのスペクトルである照射スペクトルと、弁別対象の物質のX線透過距離の推定値を示す推定距離と、前記被検体を透過したX線の経路において生じるスペクトルの歪みを示す情報とに基づいて、前記X線が前記被検体を透過した後のスペクトルとして推定される推定スペクトルを演算する。特定部は、前記推定スペクトルと、前記X線検出部で検出された、前記被検体を透過した後のスペクトルである検出スペクトルと、に基づいて、前記弁別対象の物質のX線透過距離を特定する。【選択図】図1
