Radiographic imaging device, method for achieving pixel value, and non-transitory computer readable medium

1. A radiation imaging device comprising:

a radiation amount detection pixel that generates charges in amounts corresponding to radiation amounts of irradiated radiation;

a charge amplifier that accumulates charges provided from the radiation amount detection pixel via a signal line, and that outputs output signals with signal levels corresponding to accumulated charge amounts;

an acquisition section that

acquires an output value of the charge amplifier at a point in time when a first accumulation duration has passed from an accumulation being started, as a first detection value, and that

acquires an output value of the charge amplifier at a point in time when a second accumulation duration, different from the first accumulation duration, has passed from an accumulation being started, as a second detection value; and

a derivation section that derives a difference between the first detection value and the second detection value as a pixel value of the radiation amount detection pixel,

wherein the charge amplifier includes a reset switch that, in an ON state, discharges the accumulated charges from the charge amplifier and that, in an OFF state, starts the accumulation of the charges at the charge amplifier, and

wherein the acquisition section acquires the first detection value, then puts the reset switch into the ON state, and thereafter puts the reset switch into the OFF state and acquires the second detection value.

2. The radiation imaging device according to claim 1 , wherein the radiation amount detection pixel is directly connected to the signal line.

3. The radiation imaging device according to claim 1 , further comprising:

a determination section that determines whether there is a defect at the radiation amount detection pixel on the basis of the pixel value of the radiation amount detection pixel derived by the derivation section; and

a defect map creation section that creates a defect map associating a determination result from the determination section with position information representing a position of the radiation amount detection pixel.

4. The radiation imaging device according to claim 1 , further comprising:

a plurality of imaging pixels for imaging a radiation image, each of the imaging pixel including

a sensor that generates charges in amounts corresponding to radiation amounts of irradiated radiation,

a capacitor for accumulating the charges generated by the sensor, and

a switching element connected between the capacitor and the signal line; and

a control section that controls to turn the switching element ON and OFF,

wherein, in a period in which the charge amplifier is accumulating the charges generated at the radiation amount detection pixel, the control section sets the switching element to the OFF state and stops the charges generated at the imaging pixels being provided to the charge amplifier.

5. The radiation imaging device according to claim 4 wherein,

after the acquisition section has acquired the first detection value and the second detection value, the control section sets the switching element to the ON state and provides the charges generated at the imaging pixel to the charge amplifier, and

the acquisition section acquires an output value of the charge amplifier in a period in which the charge amplifier is accumulating the charges generated at the imaging pixel as a pixel value of the imaging pixel.

6. The radiation imaging device according to claim 4 , wherein a size of the radiation amount detection pixel is smaller than the size of the imaging pixel.

7. The radiation imaging device according to claim 1 , wherein a plurality of the radiation amount detection pixel are connected to the signal line, and the charges generated at each of the plurality of radiation amount detection pixels flow together in the signal line and are provided to the charge amplifier.

8. A pixel value acquisition method that acquires a pixel value of a radiation amount detection pixel of a radiation imaging device including, the radiation amount detection pixel that generates charges in amounts corresponding to radiation amounts of irradiated radiation, and a charge amplifier that accumulates charges provided from the radiation amount detection pixel via a signal line, and that outputs output signals with signal levels corresponding to accumulated charge amounts, the pixel value acquisition method comprising:

acquiring an output value of the charge amplifier at a point in time when a first accumulation duration has passed from an accumulation at the charge amplifier of the charges generated at the radiation amount detection pixel being started, as a first detection value;

acquiring an output value of the charge amplifier at a point in time when a second accumulation duration, different from the first accumulation duration, has passed from an accumulation at the charge amplifier of the charges generated at the radiation amount detection pixel being started, as a second detection value; and

deriving a difference between the first detection value and the second detection value as a pixel value of the radiation amount detection pixel,

wherein the charge amplifier includes a reset switch that, in an ON state, discharges the accumulated charges from the charge amplifier and that, in an OFF state, starts the accumulation of the charges at the charge amplifier, and

wherein the acquiring the output value of the charge amplifier at a point in time when a first accumulation acquires the first detection value, then puts the reset switch into the ON state, and thereafter puts the reset switch into the OFF state and the acquiring an output value of the charge amplifier at a point in time when a second accumulation duration acquires the second detection value.

9. A non-transitory computer readable medium storing a program causing a computer to execute a process for controlling a radiation imaging device, the radiation imaging device including, a radiation amount detection pixel that generates charges in amounts corresponding to radiation amounts of irradiated radiation, and a charge amplifier that accumulates charges provided from the radiation amount detection pixel via a signal line, and that outputs output signals with signal levels corresponding to accumulated charge amounts, the process comprising:

acquiring an output value of the charge amplifier at a point in time when a first accumulation duration has passed from an accumulation at the charge amplifier being started, as a first detection value;

acquiring an output value of the charge amplifier at a point in time when a second accumulation duration, different from the first accumulation duration, has passed from an accumulation at the charge amplifier being started, as a second detection value; and

deriving a difference between the first detection value and the second detection value as a pixel value of the radiation amount detection pixel,

wherein the charge amplifier includes a reset switch that, in an ON state, discharges the accumulated charges from the charge amplifier and that, in an OFF state, starts the accumulation of the charges at the charge amplifier, and

wherein the acquiring the output value of the charge amplifier at a point in time when a first accumulation acquires the first detection value, then puts the reset switch into the ON state, and thereafter puts the reset switch into the OFF state and the acquiring an output value of the charge amplifier at a point in time when a second accumulation duration acquires the second detection value.