Photon counting detector and x-ray computed tomography apparatus

1. A photon-counting detector for acquiring projection data for generating a reconstructed image, comprising

a plurality of macro-pixels arranged on a semiconductor crystal having a first face and a second face, wherein the first face and the second face are parallel, wherein the plurality of macro-pixels each includes:

at least one large square micro-pixel disposed within the each macro-pixel, and

at least two small square micro-pixels disposed within the each macro-pixel, such that each of the at least two small square micro-pixels has a surface area that is less than a surface area of the at least one large square micro-pixel, wherein each side length of the at least one large square micro-pixel is greater than each side length of the at least two small square micro-pixels by an integer that is greater than 1.

2. The detector according to claim 1 , wherein a half-length of one side of the macro-pixel corresponds to a length of at least one side of the large square micro-pixel, and a half-length of one side of the large square micro-pixel corresponds to a length of at least one side of the small square micro-pixel.

3. The detector according to claim 1 , wherein the at least one large square micro-pixel has a pixel size within 300 to 600 μm.

4. The detector according to claim 1 , wherein the at least two small square micro-pixels each have a pixel size within 150 to 300 μm.

5. The detector according to claim 1 , wherein each macro-pixel includes one large square micro-pixel and twelve small square micro-pixels.

6. The detector according to claim 1 , wherein each macro-pixel includes two large micro-pixels and eight small micro-pixels.

7. The detector according to claim 1 , wherein each macro-pixel includes three large micro-pixels and four small micro-pixels.

8. The detector according to claim 1 , wherein the plurality of macro pixels includes a 16×16 macro-pixel array comprising a total of 256 macro-pixels.

9. The detector according to claim 1 , wherein the surface area of the at least one large square micro-pixel is twice as great as the surface area of each of the at least two small square micro-pixels.

10. The detector according to claim 1 , further comprising: a first set of detector responses corresponding to the at least one large square micro-pixel; and a second set of detector responses corresponding to the at least two small square micro-pixels.

11. The detector according to claim 10 , wherein information obtained from the first set of detector responses corresponding to the at least one large square micro-pixel is used to calibrate the at least two small square micro-pixels in a low-flux scanning environment.

12. The detector according to claim 10 , wherein information obtained from the second set of detector responses corresponding to the at least two small square micro-pixels is used to calibrate the at least one large square micro-pixel in a high-flux scanning environment.

13. The detector according to claim 1 , further comprising a cathode electrode covering the first face, the plurality of macro-pixels covering the second face.

14. An X-ray CT apparatus, comprising: an X-ray tube configured to emit X-rays; and the detector according to claim 1 , configured to detect X-rays that have been emitted from the X-ray tube and have passed through a subject.

15. The detector according to claim 1 , wherein the plurality of macro-pixels each includes:

a large square micro-pixel disposed at a respective center of the respective macro-pixel, and

the at least two small square micro-pixels disposed adjacent each edge of the respective large square micro-pixel.

16. A photon-counting detector, comprising

a plurality of macro-pixels arranged on a semiconductor crystal having a first face and a second face, wherein the first face and the second face are parallel, wherein the plurality of macro-pixels each includes:

a large micro-pixel disposed at a respective center of the respective macro-pixel, and

N small micro-pixels disposed adjacent each edge of the respective large micro-pixel,

wherein each of the N small micro-pixels disposed adjacent each edge of the respective large micro-pixel has a surface area that is less than a surface area of the large micro-pixel.

17. The detector according to claim 16 , wherein N is 4 such that the each respective large micro-pixel is disposed in the respective center portion of each of the plurality of macro-pixels with the twelve small micro-pixels forming a respective periphery around the each respective large micro-pixel.

18. A photon-counting detector for acquiring projection data for generating a reconstructed image, comprising

a plurality of macro-pixels arranged on a semiconductor crystal having a first face and a second face, wherein the first face and the second face are parallel, wherein the plurality of macro-pixels each includes:

a large micro-pixel disposed within the each macro-pixel and at least two small micro-pixels disposed within the each macro-pixel, wherein a half-length of one side of the macro-pixel corresponds to a length of at least one side of the large micro-pixel, and

each of the at least two small micro-pixels having a surface area that is less than a surface area of the large micro-pixel.

19. A photon-counting detector for acquiring projection data for generating a reconstructed image, comprising

a plurality of macro-pixels arranged on a semiconductor crystal having a first face and a second face, wherein the first face and the second face are parallel, and wherein the plurality of macro-pixels each includes:

a large micro-pixel disposed within the each macro-pixel and at least two small micro-pixels disposed within the each macro-pixel, wherein information obtained from detector responses corresponding to the at least one large micro-pixel is used to calibrate the at least two small micro-pixels in a low-flux scanning environment, and

each of the at least two small micro-pixels having a surface area that is less than a surface area of the large micro-pixel.