PROBLEM TO BE SOLVED: To provide a technology to acquire an X-ray projection image of high resolution without causing a problem to turning of an X-ray generator and an X-ray detector.SOLUTION: An X-ray generator 42 and an X-ray detector 52 are turned around a head of a subject M1 so that X-ray beams BX1 are irradiated onto an imaging region ROI from a plurality of directions to acquire an X-ray projection image. The X-ray detector 52 is caused to approach a tomography of interest LOI while the X-ray generator 42 is caused to be separated from the tomography of interest LOI when a central axis X-ray CBX1 passing through a turning central axis RA1 out of the X-ray beams BX1 is orthogonal to the tomography of interest LOI as compared with when it is not orthogonal thereto.SELECTED DRAWING: Figure 10【課題】Ｘ線発生器およびＸ線検出器の旋回に支障を来すことなく、高解像度のＸ線投影画像を取得する技術を提供する。【解決手段】Ｘ線発生器４２およびＸ線検出器５２を、被写体Ｍ１の頭部の周囲において旋回させることによって、撮影領域ＲＯＩに複数の方向からＸ線ビームＢＸ１を照射して、Ｘ線投影画像を得る。Ｘ線ビームＢＸ１のうち旋回中心軸ＲＡ１を通る中心軸Ｘ線ＣＢＸ１が、関心断層ＬＯＩに直交するときに、直交していないときと比べて、Ｘ線検出器５２を関心断層ＬＯＩに接近させるとともに、Ｘ線発生器４２を関心断層ＬＯＩから離隔させる。【選択図】図１０
