PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus which prevents an increase in temperature when a cooling fan for a data acquisition device breaks down to continuously keep on scanning.SOLUTION: In the X-ray CT apparatus equipped with an X-ray source, a multichannel X-ray detector, a rotating part for rotating the X-ray source and the X-ray detector about the body axis of the subject, a projection data acquisition part for acquiring X-ray projection data from detected signals of the X-ray detector, and a group of cooling fans comprising a plurality of fans for cooling the projection data acquisition part for scanning the subject, the X-ray CT apparatus is equipped with a clock frequency generating part for imparting an operation clock frequency to the projection data acquisition part and a failure detecting part for detecting an abnormal state of each fan in the group of cooling fans, and the clock frequency generating part reduces the operation clock frequency of the projection data acquisition part to drive the X-ray CT apparatus in a degeneration operation mode when the abnormal state of a fan in the group of cooling fans is detected by the failure detecting part.COPYRIGHT: (C)2009,JPO&INPIT【課題】データ収集装置の冷却用ファンが故障した場合でも、温度上昇を防ぎ継続してスキャンを続行可能なX線CT装置を提供する。【解決手段】X線源と、多チャンネルのX線検出器と、上記X線源及び上記X線検出器を上記被検体の体軸の周囲で回転させる回転部と、前記X線検出器の検出信号に基づいてX線投影データを収集する投影データ収集部と、該投影データ収集部を冷却する複数のファンからなる冷却ファン群とを備え、上記被検体に対してスキャンを行うX線CT装置において、上記投影データ収集部に動作クロック周波数を与えるクロック周波数発生部と、上記冷却ファン群の異常状態をファン毎に検出する異常検出部とを備え、該異常検出部により上記冷却ファン群の一つのファンの異常状態が検出された場合に、上記クロック周波数発生部は、上記投影データ収集部の動作クロック周波数を低減して縮退運転モードで運転させる。【選択図】図2
