PROBLEM TO BE SOLVED: To prevent the omission of part of projection data required for image reconstruction in an X-ray computed tomography apparatus which can perform ECG gated reconstruction.SOLUTION: The X-ray computed tomography apparatus includes an X-ray source 101 generating X-rays, a high voltage generating unit 104 generating a high voltage applied to the X-ray source, and an X-ray detector 102 detecting X-rays transmitted through a subject to be examined to generate projection data, and further includes an ECG gated scanning unit performing scanning synchronous with ECG gated signals and electrocardiographic signals of a subject to be examined, and a control unit 212 generating a relatively high dose of X-rays in a first period including a specific phase and required for reconstruction of a tomogram, and controlling generation/stop of intensity modulation of X-rays generating a relatively low dose of X-rays and steady control of X-rays for steadily maintaining a relatively high dose of X-rays, in a second period other than the first period in a cardiac cycle of the subject, corresponding to an R-R interval from a given R wave to the next R wave of a heart rate of the subject or the electrocardiographic waveform signals in parallel with scanning.COPYRIGHT: (C)2012,JPO&INPIT【課題】心電同期再構成の可能なX線CT装置において画像再構成に必要な投影データの一部欠落を防止すること。【解決手段】X線CT装置は、X線を発生するX線源101、X線源に印加するための高電圧を発生する高電圧発生部104と、投影データを発生するために被検体を透過したX線を検出するX線検出器を102有し、被検体の心電図同期信号又は心電図波形信号に同期してスキャンを行う心電同期スキャン手段と、断層像を再構成するための特定位相を含む第1の期間に比較的高線量のX線を発生し、被検体の心拍周期のうちの第1の期間以外の第2の期間に比較的低線量のX線を発生するX線強度変調制御と比較的高X線量のX線を定常的に維持するX線定常制御とをスキャンと並行して得られた被検体の心拍数又は前記心電図波形信号のあるR波から次のR波までのR-R間隔に応じて切り替える制御部212とを備える。【選択図】 図1
