PROBLEM TO BE SOLVED: To improve photon detection accuracy by suppressing variation in count rate characteristics due to self-heating of a photon counting circuit in a radiography apparatus including a photon counting-type detector.SOLUTION: The photon counting-type detector includes: a semiconductor layer that receives photons of a radiant ray to generate electric charge； a photon counting circuit that reads an electric current from a pixel electrode formed on one surface of the semiconductor layer； and a heating amount compensation circuit that controls a heating amount of the photon counting circuit according to a count rate of the photon counting circuit. The heating amount compensation circuit operates in a low count rate to execute such control that the heating amount generated by the photon counting circuit in the low count rate becomes substantially equal to the heating amount generated by the photon counting circuit in the high count rate.SELECTED DRAWING: Figure 2【課題】光子計数型検出器を備えた放射線撮像装置において、光子計数回路の自己発熱による計数率特性の変動を抑制し、光子検出精度を向上させる。【解決手段】光子計数型検出器は、放射線の光子を受けて電荷を発生する半導体層と、該半導体層の一方の面に形成された画素電極から電流を読み出す光子計数回路と、該光子計数回路の計数率に応じて光子計数回路の発熱量を制御する発熱量補償回路とを備える。発熱量補償回路は、計数率が低い時に動作し、低計数率時に光子計数回路が発する熱量が、高計数率時に光子計数回路が発する熱量と略同一となるように制御する。【選択図】図２
