PROBLEM TO BE SOLVED: To automatically control X rays to an appropriate exposure amount without reducing the S/N value of a signal value in a pixel.SOLUTION: An AEC control signal is transmitted, which is continuously at a high level from an X-ray exposure start time t1 with respect to a gate line 3-2 which is set as an AEC line, for example, among a plurality of detection elements 2-11 to 2-nm in an X-ray detector 2. The electric charge of the detection element 2-22 in one pixel, for example, on the AEC line is stored during the transmission of the AEC control signal. Then, the exposure of the X-ray from an X-ray source 1 is stopped at the point of time t2 when the electric charge storage value H reaches a threshold G, i.e., the appropriate value of exposure amount of the X-ray to be exposed to a subject S.COPYRIGHT: (C)2010,JPO&INPIT【課題】画素の信号値のS/N値を低下させることなくX線を適正露光量に自動制御すること。【解決手段】X線検出器2における複数の検出素子2-11~2-nmのうち1ライン、例えばAECラインとして設定したゲート線3-2に対してX線曝射開始時t1から連続してハイレベルとなるAEC制御信号を送出し、かつAEC制御信号の送出中に当該AECライン上の例えば1画素の検出素子2-22の電荷を蓄積し、この電荷蓄積値Hが閾値Gすなわち被検体Sに曝射するX線量の適正値に達した時点t2でX線源1からのX線の曝射を停止する。【選択図】図2
