PROBLEM TO BE SOLVED: To reliably prevent an error in the detection of the start of application of radiation.SOLUTION: A first determination unit 62 compares an electric signal Di outputted while all TFTs 43 are turned on with a first threshold value th1, and determines that the application of an X-ray has started if the electric signal Di is equal to or greater than the first threshold value th1. A second determination unit 63 compares the first-order differentiation value Di of the electric signal Di outputted while all the TFTs 43 are turned off with second and third threshold values th2, th3. If the first-order differentiation value Di is within or outside of a range defined by the second and third threshold values th2, th3 in an entire determination section, the determination by the first determination unit 62 is determined to be correct. If the first-order differentiation value moves into and out of the range in the determination section, the determination by the first determination unit 62 is determined to be wrong. When the determination by the first determination unit 62 is determined to be correct, the TFTs 43 are kept off and an FDP 36 is caused to perform accumulation action continuously.COPYRIGHT: (C)2012,JPO&INPIT【課題】放射線の照射開始を誤って検出することを確実に防止する。【解決手段】第一判定部62は、全てのTFT43をオンにした状態で出力される電気信号Diと第一閾値th1を比較し、電気信号Diが第一閾値th1以上となったときにX線の照射が開始されたと判定する。第二判定部63は、全てのTFT43をオフにした状態で出力される電気信号Diの一階微分値Di’と第二、第三閾値th2、th3を比較する。全判定区間で一階微分値Di’が第二、第三閾値th2、th3で規定する範囲内または範囲外にあった場合は第一判定部62の判定が正しいと判定する。判定区間において範囲内と範囲外を行ったり来たりする場合は第一判定部62の判定が誤っていると判定する。第一判定部62の判定が正しいと判定した場合はTFT43のオフ状態を継続しFPD36に蓄積動作を継続して行わせる。【選択図】図4
