A radiation source is relatively moved with respect to a radiation detector, on which a plurality of short-circuited pixels formed by short-circuiting TFT switches are arranged across the entire surface thereof. Radiation is irradiated onto a subject at a plurality of radiation source positions, in association with movement of the radiation source. A plurality of images corresponding to each of the plurality of the radiation source are obtained. Positions of detection short-circuited pixels for detecting a dose of radiation are set, respectively corresponding to the plurality of radiation source positions. The dose of radiation output from the radiation source is controlled, based on electric signals read out from the detection short-circuited pixels, at each of the plurality of radiation source positions.