Radiation detection apparatus

1. A radiation detection apparatus, comprising:

a scintillator configured to emit scintillation light based on incidence of a radiation;

a pixel substrate comprising an array of a plurality of pixels,

wherein each pixel of the plurality of pixels is configured to:

photoelectrically convert the scintillation light; and

output a pixel signal based on the photoelectric conversion of a light amount of the scintillation light;

a detection circuit substrate comprising an Analog to Digital (A/D) conversion unit configured to:

A/D convert the pixel signal; and

output digital data for the pixel signal of each pixel of the plurality of pixels,

wherein the detection circuit substrate is stacked on the pixel substrate;

an adjustment mechanism configured to adjust a quantization width of the A/D conversion, wherein the quantization width of the A/D conversion is adjusted based on amplification of the pixel signal; and

a compression unit configured to compress the digital data outputted from the A/D conversion unit.

2. The radiation detection apparatus according to claim 1 , wherein

the scintillator includes a cell type scintillator in which a plurality of scintillator cells is arranged in an array,

each scintillator cell of the plurality of scintillator cells is isolated from each other by a barrier wall, and

one or more pixels of the plurality of pixels are allocated to each scintillator cell of the plurality of scintillator cells.

3. The radiation detection apparatus according to claim 2 , wherein

two or more pixels of the plurality of pixels are allocated to each scintillator cell of the plurality of scintillator cells; and

the compression unit is further configured to add the digital data of the two or more pixels allocated to each scintillator cell of the plurality of scintillator cells to compress the digital data.

4. The radiation detection apparatus according to claim 2 , wherein

two or more pixels of the plurality of pixels are allocated to each scintillator cell of the plurality of scintillator cells; and

the compression unit is further configured to select a position of a pixel of the two or more pixels allocated to the scintillator cell as an incident position of the radiation, wherein the digital data of the pixel is maximum among the digital data of the two or more pixels allocated to the scintillator cell.

5. The radiation detection apparatus according to claim 2 , wherein

two or more pixels of the plurality of pixels are allocated to each scintillator cell of the plurality of scintillator cells; and

the compression unit is further configured to:

add the digital data of the two or more pixels allocated to the scintillator cell;

compress the digital data based on the addition; and

select a position of a pixel of the two or more pixels allocated to the scintillator cell as an incident position of the radiation, wherein the digital data of the pixel is maximum among the digital data of the two or more pixels allocated to the scintillator cell.

6. The radiation detection apparatus according to claim 1 , further comprising a plurality of light detection blocks arranged in an array, wherein

each light detection block of the plurality of light detection blocks includes the pixel substrate and the detection circuit substrate stacked with each other.

7. The radiation detection apparatus according to claim 6 , wherein each detection block of the plurality of light detection blocks includes the compression unit.

8. The radiation detection apparatus according to claim 6 , wherein

the plurality of light detection blocks are on a first semiconductor substrate,

and

a plurality of pieces of the light detection blocks cut from the first semiconductor substrate are arranged in the array on a second semiconductor substrate.

9. The radiation detection apparatus according to claim 1 , further comprising a radiation generation unit configured to generate the radiation, wherein the radiation generation unit is at a position that sandwiches a subject.

10. The radiation detection apparatus according to claim 1 , wherein

each pixel of the plurality of pixels has a photodiode (PD) having a substantially rectangular planar shape whose long side is equal to or longer than twice short side.

11. The radiation detection apparatus according to claim 10 , wherein each pixel of the plurality of pixels has a plurality of PDs having the substantially rectangular planar shape whose long side is equal to longer than twice short side.

12. The radiation detection apparatus according to claim 1 , wherein the quantization width of the A/D conversion is adjusted to one of a quantization width corresponding to the pixel signal of less than one electron or hole, or to a quantization width corresponding to the pixel signal of at least one electron or at least one hole.

13. The radiation detection apparatus according to claim 1 , wherein

the A/D conversion unit includes:

a comparator configured to:

compare a reference signal that changes with a specific inclination and the pixel signal with each other; and

output a result of the comparison between the reference signal and the pixel signal; and

a counter configured to:

count a period of time until a relationship in magnitude between the reference signal and the pixel signal reverses, based on the result of the comparison; and

output a count value of the period of time, and

the radiation detection apparatus further comprising an amplifier configured to amplify the pixel signal to be supplied to the comparator, wherein

the amplifier has an adjustable gain, and

the amplifier with the adjustable gain is provided as the adjustment mechanism.

14. The radiation detection apparatus according to claim 1 , wherein

the A/D conversion unit includes:

a comparator configured to:

compare a reference signal that changes with a specific inclination and the pixel signal with each other; and

output a result of the comparison between the reference signal and the pixel signal; and

a counter configured to:

count a period of time until a relationship in magnitude between the reference signal and the pixel signal reverses, based on the result of the comparison; and

output a count value of the period of time, and

the radiation detection apparatus further comprising a reference signal generation unit as the adjustment mechanism, wherein the reference signal generation unit is configured to:

generate the reference signal; and

adjust the specific inclination of the reference signal to the quantization width of the A/D conversion.

15. The radiation detection apparatus according to claim 1 , wherein

the A/D conversion unit includes:

a comparator configured to:

compare a reference signal that changes with a specific inclination and the pixel signal with each other; and

output a result of the comparison between the reference signal and the pixel signal; and

a counter configured to:

count a period of time until a relationship in magnitude between the reference signal and the pixel signal reverses, based on the result of the comparison; and

output a count value of the period of time, and

a pixel of the plurality of pixels has, as the adjustment mechanism, a gain adjustment unit configured to adjust a gain of the pixel signal to be supplied to the comparator.