PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus that allows a clear CT image to be acquired by a successive approximation method.SOLUTION: An X-ray CT apparatus includes an X-ray tube 5 and an X-ray detector 9 disposed across a treatment table 7, and an image generation part 17 for generating a tomographic image of a patient P based on the X-ray detected by the X-ray detector 9. Representing a region where all rotated regions T to be detected are overlapped with one another when the regions T to be detected, which are regions including all line segments connecting the X-ray tube 5 and each detection pixel 9a of the X-ray detector 9, are rotated, as region R1, and representing a region defined outside region R1 as region R2, the image generation part 17 includes a smoothing processing part 17a for acquiring smoothing data by subjecting a linear attenuation coefficient of a voxel located in region R2 to smoothing processing when calculating a linear attenuation coefficient of each voxel included in a cross section, and a linear attenuation coefficient calculation part 17b for calculating a linear attenuation coefficient of a voxel located in region R1 based on the smoothing data.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2018,JPO&INPIT【課題】逐次近似法によって鮮明な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CT装置は、治療台7を挟んで配置されるX線管5及びX線検出器9と、X線検出器9で検出したX線に基づいて、患者Pの断層の画像を生成する画像生成部17と、を備え、X線管5とX線検出器9の各々の検出画素9aとを結ぶすべての線分を含む領域である被検出領域Tを回転させたときに、すべての回転させた被検出領域Tが互いに重複する領域を領域R1とし、領域R1の外側に規定される領域を領域R2としたときに、画像生成部17は、断層に含まれる各ボクセルの線減弱係数を算出するときに、領域R2に位置するボクセルの線減弱係数に平滑化処理を施して平滑化データを得る平滑化処理部17aと、平滑化データに基づいて、領域R1に位置するボクセルの線減弱係数を算出する線減弱係数算出部17bとを有する。【選択図】図2
