PROBLEM TO BE SOLVED: To provide an X-ray CT system that attains a desired image quality index value expected at the time of scan planning even in the event when the subject lies out of position with regard to the scanner rotational center.SOLUTION: The X-ray CT scanner comprises an operation means 4a to input X-ray photographing conditions and desired image quality index values, a memory means 25 for storing CT images reconstructed by an image reconstruction means 24, various data and scanogram data acquired from a subject 2 in the process of operating a preparation section, and a scan programming means 28 that analyzes the scanograms stored in the memory means 25, generates appropriate three-dimensional models of the subject 2 even in the event when the subject 2 lies out of position with regard to the scanner rotational center, forecasts image noises from the obtained three-dimensional models of the subject 2 corresponding to his/her photographed bodily part, and a scan programming means 28 for setting an appropriate modulation pattern of irradiating X-ray volume based on the comparison with desired image index values input from the operation means 4a.COPYRIGHT: (C)2007,JPO&INPIT【課題】被検体がスキャナ回転中心からずれていても、スキャン計画時に想定した画質指標所望値を達成するX線CT装置を提供する。【解決手段】X線撮影条件や画質指標所望値を入力する操作手段4aと、画像再構成手段24で再構成されたCT画像や各種データ及び準備部操作段階で被検体2より取得したスキャノグラムデータを記憶する記憶手段25と、記憶手段25に記憶されたスキャノグラムデータを解析して、被検体2がスキャナ回転中心からずれている場合でも、適切な被検体三次元モデルを生成し、得られた被検体三次元モデルから被検体2の撮影部位に応じた画像ノイズを予測し、操作手段4aより入力された画質指標所望値との比較から、照射X線量の適切な変調パターンを設定するスキャン計画手段28とから構成したものである。【選択図】図2
