Radiation imaging apparatus and radiation detection system

1. A radiation imaging apparatus for determining the presence or absence of radiation irradiation and determining a radiation dose, said radiation imaging apparatus comprising:

a sensor portion including a pixel array configured to acquire an image signal indicating detected radiation, and a plurality of detection elements arranged in the pixel array and configured to detect the radiation; and

a circuit configured to read out at least the image signal from the sensor portion, wherein

the circuit generates a first signal for determining the presence or absence of radiation irradiation, and a second signal for determining the radiation dose,

the first signal corresponds to a combination of signals from detection elements of a first subset of the plurality of detection elements provided by an electrical connection to the circuit collectively, and the second signal corresponds to a combination of signals from detection elements of a second subset of the plurality of detection elements provided by an electrical connection to the circuit collectively, and

the number of detection elements of the first subset is greater than the number of detection elements of the second subset.

2. The apparatus according to claim 1 , wherein the sensor portion further includes a plurality of detection signal lines to which the detection elements are connected, and a combining portion configured to combine signals of the plurality of detection signal lines by electric connection to the circuit collectively, and

the plurality of detection elements are connected to any one of the plurality of detection signal lines.

3. The apparatus according to claim 2 , wherein the combining portion includes switch elements operable to connect the plurality of detection signal lines to the circuit.

4. The apparatus according to claim 2 , wherein the circuit includes a first signal processing circuit for processing the first signal, and a second signal processing circuit for processing the second signal, and

the combining portion includes an element configured to capacitively couple the plurality of detection signal lines with the first signal processing circuit.

5. The apparatus according to claim 1 , wherein the circuit further includes a power supply circuit to apply a bias voltage to the plurality of detection elements via bias line,

the power supply monitors a current flowing in the bias line,

the presence or absence of radiation irradiation is determined based on the first signal which is based on a change in the current flowing in the bias line monitored by the power supply, and

the radiation dose is determined based on the second signal which is read out via at least one of an image signal line and the detection signal line.

6. The apparatus according to claim 2 , wherein the detection element comprises a conversion element configured to generate charges corresponding to the radiation, an amplification MOS transistor arranged to output a signal corresponding to the charges from the conversion element to the detection signal line, and a reset switch arranged to reset the conversion element.

7. The apparatus according to claim 6 , wherein the detection element is arranged to output the image signal corresponding to the radiation to the detection signal line.

8. The apparatus according to claim 1 , wherein the circuit further comprises:

a first signal processing circuit configured to combine and process the first signal; and

a second signal processing circuit configured to process the second signal, wherein

during determining the presence or absence of radiation irradiation, the first signal processing circuit is operated, and operation of the second signal processing circuit is stopped, and

during determining the radiation dose, the second signal processing circuit is operated.

9. A radiation detection system comprising:

a radiation source configured to generate radiation; and

a radiation imaging apparatus defined in claim 1 .