Radiation detection apparatus, control method of the same, and radiation imaging system

A radiation detection apparatus includes a pixel array including pixels each including a conversion element and a switch element, an acquisition unit configured to acquire a first signal generated in the pixel array while at least one switch element of the pixels is in a conductive state, and a second signal generated in the pixel array while the switch elements are in a non-conductive state, an evaluation value determination unit configured to determine, based on the first signal, an evaluation value having a correlation with a radiation dose, a threshold value determination unit configured to determine a threshold value based not on the evaluation value but on the second signal, and a determination unit configured to determine, based on comparison between the evaluation value and the threshold value, whether the pixel array is being irradiated with radiation.