PROBLEM TO BE SOLVED: To correctly and accurately set the optimum heartbeat phase in an X-ray CT apparatus.SOLUTION: The X-ray CT apparatus 10 includes: an X-ray tube for irradiating a patient with a cone-beam X ray an X-ray detector having a plurality of X-ray detecting elements in the column direction for detecting X rays and an electrocardiograph for measuring the heartbeat information of the patient. The X-ray CT apparatus 10 generates images inside the patient based on the projection data based on the detected X rays and the heartbeat information. The X-ray CT apparatus 10 also includes a bundling part 56 for generating projection data by selecting corresponding X-ray detecting elements astride the center in the column direction in the number smaller than the number of X-ray detecting elements in the column direction, and bundling the projection data based on the selected X-ray detecting elements in a required column and an optimum phase determining part 57 for determining the optimum heartbeat phase based on the amount of movement by finding the amount of movement corresponding to a plurality of heartbeat phases based on the bundled projection data.COPYRIGHT: (C)2010,JPO&INPIT【課題】X線CT装置において、最適心拍位相を正確に精度よく設定すること。【解決手段】患者に向けてコーンビームX線を照射するX線管と、列方向に複数のX線検出素子を具備しX線を検出するX線検出器と、患者の心拍情報を計測する心電計とを備え、検出されたX線に基づく投影データ及び心拍情報を基に患者内部の画像を生成するX線CT装置10は、列方向のX線検出素子の数より小さく、前記列方向の中心を跨ぐ所要列に相当するX線検出素子を選択し、選択された所要列のX線検出素子に基づく前記投影データを列方向に束ねて束ね投影データを生成する束ね処理部56と、束ね投影データを基に、複数の心拍位相に対応する動き量を求め、動き量を基に、最適心拍位相を決定する最適位相決定部57と、を有する。【選択図】 図3
