Radiation image detection apparatus and radiation image photographing system

A radiation image detection apparatus, comprising:

• an imaging unit including an image receiving unit having a pixel array configured to receive radiation and to accumulate an electrical charge, and an image data generation unit configured to generate an image data based on the electrical charge output from the image receiving unit;
• a communication unit configured to transmit the image data acquired by the imaging unit to an external equipment;
• a communication speed detection unit configured to monitor the communication speed of the communication unit;
• and
• a control unit configured to drive the imaging unit so that a radiation image data is acquired during an exposure to radiation, the image receiving unit is reset after acquiring the radiation image data, and a dark image data is acquired during a non-exposure to the radiation;
• wherein the image data generation unit generates a reduced image data from the radiation image data, and
• the control unit changes at least one of a reset time of the image receiving unit and a reduction ratio of the reduced image data on the basis of the communication speed detected by the communication speed detection unit such that the transmission of the reduced image data by the communication unit is completed at least prior to reading-out the electrical charge signal from the image receiving unit when acquiring the dark image.