Radiation detector and computed tomography apparatus using the same
The radiation detector includes a plurality of image pixels each including a plurality of counting pixels. Each of the plurality of counting pixels includes a radiation absorption layer that converts incident photons, which are incident on a corresponding counting pixel of the plurality of counting pixels, into an electrical signal, and a photon processor configured to compare the electrical signal with a reference value, output an output signal according to a result of the comparison, count a number of photons which are incident on the corresponding counting pixel based on the output signal, and store the counted number of photons.
1. A radiation detector comprising:
a plurality of image pixels, each image pixel of the plurality of image pixels including a plurality of counting pixels,
wherein each counting pixel of the plurality of counting pixels comprises:
a radiation absorption layer that converts incident photons, which are incident on a counting pixel of the plurality of counting pixels, into an electrical signal, and
a photon processor circuit that corresponds to the counting pixel in a one to one relationship, and is configured to:
compare the electrical signal with a reference value, and output an output signal according to a result of a comparison,
count a number of photons which are incident on the counting pixel based on the output signal, and
store the counted number of photons.
2. The radiation detector of claim 1 , wherein the photon processor circuit of the counting pixel counts the number of photons that is smaller than the number of photons incident on each image pixel of the plurality of image pixels.
3. The radiation detector of claim 1 , wherein each counting pixel of the plurality of counting pixels separately performs counting operation and storing operation for the number of photons incident on the counting pixel.
4. The radiation detector of claim 1 , wherein the photon processor circuit comprises:
a comparator that compares the electrical signal transferred from the radiation absorption layer included in the counting pixel with the reference value to determine whether the electrical signal exceeds the reference value, and outputs the output signal in response to the electrical signal exceeding the reference value, and
a counting memory that counts the number of photons incident on the counting pixel based on the output signal of the comparator, and stores the counted number of photons.
5. The radiation detector of claim 1 , wherein the photon processor circuit comprises:
a comparator that compares the electrical signal transferred from the radiation absorption layer included in the counting pixel with the reference value to determine whether the electrical signal exceeds the reference value, and outputs the output signal in response to the electrical signal exceeding the reference value;
a counter that counts the number of photons incident on the counting pixel based on the output signal of the comparator; and
a memory that stores the counted number of photons.
6. The radiation detector of claim 1 , wherein the counted number of photons, which are incident on the counting pixel, are used to generate one pixel value in an image.
7. The radiation detector of claim 1 , wherein:
the plurality of counting pixels included in at least one image pixel of the plurality of image pixels are divided into at least two sub-pixel groups, and
a total number of photons counted by each sub-pixel group of the least two sub-pixel groups is used to generate one pixel value in an image.
8. The radiation detector of claim 7 , further comprising:
an image processor configured to generate the image comprising a computed tomography image.
9. The radiation detector of claim 1 , wherein:
the plurality of counting pixels arranged adjacent each other and included in one of the plurality of image pixels comprises a counting pixel group, and
a total number of the incident photons, counted by the counting pixel group, corresponds to one pixel value in an image.
10. The radiation detector of claim 1 , wherein the photon processor circuit comprises a memory and is further configured to store the counted number of photons in the memory,
wherein the memory is included in each photon processor circuit to individually correspond to each counting pixel included into each portion of the radiation absorption layer, respectively.
11. A tomography apparatus comprising:
the radiation detector of claim 1 ; and
an image processor coupled to the radiation detector and configured to generate a tomography image.
12. The tomography apparatus of claim 11 , wherein the image processor generates the tomography image in which one pixel value of the tomography image is obtained by using a total number of photons counted by each image pixel of the plurality of image pixels.
13. The tomography apparatus of claim 11 , wherein:
the plurality of counting pixels included in at least one image pixel of the plurality of image pixels are divided into at least two sub-pixel groups, and
the image processor generates the tomography image in which one pixel value of the tomography image is obtained by using a total number of photons counted by each sub-pixel group of the least two sub-pixel groups.
14. The tomography apparatus of claim 13 , wherein the image processor adjusts a number of the plurality of counting pixels included in each sub-pixel group of the least two sub-pixel groups according to a resolution of the tomography image.