Radiation imaging apparatus, radiation imaging system, and method of controlling radiation imaging apparatus

A radiation imaging apparatus comprising:

• a pixel unit including a plurality of pixels and configured to generate image data in response to receiving irradiation of radiation from a radiation generation apparatus;
• at least one processor;
• and
• a memory coupled to the at least one processor, the memory having instructions that, when executed by the at least processor, perform to:
• acquire irradiation information regarding a radiation irradiation area or an irradiation position of the pixel unit irradiated by the radiation generation apparatus;
• calculate brightness information of each of successive pieces of image data obtained by operating the pixel unit at a predetermined frame rate based on each of the successive pieces of image data and the irradiation information;
• store a timing of calculating the brightness information;
• generate irradiation condition information regarding an irradiation condition of the radiation generation apparatus based on the brightness information;
• transmit the irradiation condition information to the radiation generation apparatus
• recalculate the brightness information based on the irradiation information when a fluctuation of the brightness information exceeds a threshold value;
• and
• transmit irradiation condition information based on a period of time elapsed between a timing of calculating the recalculated brightness information and a timing of calculating brightness information calculated immediately before.