An X-ray CT apparatus and a contrast imaging method which can obtain an image having a good contrast effect without re-injecting a contrast agent even when the imaging position is overtaking the position of the contrast medium during imaging using a contrast medium , The X-ray CT apparatus determines whether or not the current imaging position overtakes the contrast medium during actual imaging, and when overtaking the contrast medium, the X-ray CT apparatus re-sets the imaging condition and is reset When re-imaging is performed under the imaging conditions and determination of overtaking of the contrast agent is made, it is based on difference data between measurement data obtained by non-contrast imaging performed prior to actual imaging and measurement data obtained by actual imaging Therefore, it is unnecessary to reconstruct an image during photographing in order to check the presence or absence of a contrast effect, so it is possible to perform overtaking judgment at high speed and immediately shift to re-photographing.造影剤を用いた撮影中に撮影位置が造影剤の位置を追い越す場合にも、造影剤を再注入せずに良好な造影効果を有する画像を得ることが可能なX線CT装置及び造影撮影方法を提供するために、X線CT装置は、本撮影中に、現在の撮影位置が造影剤を追い越すか否かを判定し、造影剤を追い越す場合は、撮影条件を再設定し、再設定された撮影条件で再撮影を実行し、造影剤の追い越しを判定する際は、本撮影の前に行われる非造影撮影により得られた計測データと本撮影により得られる計測データとの差分データに基づく判定を行い、このため、造影効果の有無を調べるために撮影中に画像を再構成する必要がなく、追い越し判定を高速に行って、ただちに再撮影へ移行できる。
