PROBLEM TO BE SOLVED: To provide a radiation imaging apparatus capable of setting an appropriate threshold value for instantaneously detecting the presence of the irradiation of the radiation with high accuracy.SOLUTION: A radiation imaging apparatus comprises: a pixel array 101 in which a plurality of pixels P respectively containing conversion elements S and switch elements T, are arranged thereon a drive circuit 102 for controlling the switch element T between conducting and non-conducting states a detection part for outputting a detection signal DS having fluctuations suited to a change in an irradiation intensity of the radiation 133 to the pixel array 101 and a calculation processing part 120 for calculating a start threshold Sth for detecting the start of the irradiation of the radiation 133 on the basis of the detection signal DS output from the detection part while the radiation 133 is not irradiated to the pixel array 101 in which the switch element T is made to sequentially be in a conducting state row by row by the drive circuit 102, and the detection signal DS output from the detection part while the radiation 133 is irradiated to the pixel array 101 in which the switch element T is made to sequentially be in a conducting state row by row by the drive circuit 102.COPYRIGHT: (C)2014,JPO&INPIT【課題】 放射線の照射の有無を即時に高い精度で検知するために適切な閾値の設定が可能な放射線撮像装置を提供する。【解決手段】 各々が変換素子Sとスイッチ素子Tとを含む複数の画素Pが配置された画素アレイ101と、スイッチ素子Tの導通状態と非導通状態とを制御するする駆動回路102と、画素アレイ101への放射線133の照射の強度に応じた変動を有する検知信号DSを出力する検知部と、スイッチ素子Tが駆動回路102によって行単位で順次に導通状態とされている画素アレイ101へ放射線が照射されていない期間に検知部から出力される検知信号DSと、スイッチ素子Tが駆動回路102によって行単位で順次に導通状態とされている画素アレイ101へ放射線が照射されている期間に検知部から出力される検知信号DSと、に基づいて、放射線133の照射の開始を検知するための開始閾値Sthを算出する演算処理を行う演算部120と、を含む。【選択図】 図1
