PROBLEM TO BE SOLVED: To optimize switching control of a voltage applied to an X-ray tube such that contrast of an obtained image becomes large, in an X-ray CT (Computed Tomography) apparatus including the X-ray tube wherein a positive voltage is applied to a positive electrode and a negative voltage is applied to a negative electrode, and photographing a target while changing over the X-ray tube voltage to a plurality of set voltages.SOLUTION: An X-ray CT apparatus includes: a first voltage generator generating the positive voltage applied to the positive electrode of the X-ray tube, and changing over the positive voltage to a prescribed voltage according to a positive voltage switching signal based on an X-ray tube voltage switching signal a second voltage generator generating the negative voltage applied to the negative electrode of the X-ray tube, and changing over the negative voltage to a prescribed negative voltage according to a negative voltage switching signal based on the X-ray tube voltage switching signal and a control section controlling switching timing in at least one of the positive voltage switching signal and the negative voltage switching signal such that a time lag amount between timing wherein the generated positive voltage is switched to the prescribed positive voltage and timing wherein the generated negative voltage is switched over to the prescribed voltage becomes small.COPYRIGHT: (C)2012,JPO&INPIT【課題】陽極に正電圧が印加され陰極に負電圧が印加されるX線管を有しており、X線管電圧を複数の設定電圧に切り換えながら対象を撮影するX線CT装置において、得られる画像のコントラストが大きくなるようにX線管に印加する電圧の切換制御を最適化する。【解決手段】X線管の陽極に印加する正電圧を発生させ、X線管電圧切換信号に基づく正電圧切換信号に応じて所定の正電圧に切り換える第一電圧発生器と、X線管の陰極に印加する負電圧を発生させ、X線管電圧切換信号に基づく負電圧切換信号に応じて所定の負電圧に切り換える第二電圧発生器と、発生する正電圧が上記所定の正電圧に切り換わるタイミングと、発生する負電圧が上記所定の負電圧に切り換わるタイミングとのずれ量が小さくなるように、正電圧切換信号および負電圧切換信号の少なくとも一方における切換タイミングを制御する制御手段とを備える構成とする。【選択図】図4
