Radiation detector and computer tomography apparatus including the same

A radiation detector comprising a plurality of pixels configured to detect radiation, wherein each of the plurality of pixels comprises a plurality of sub-pixels, and each of the plurality of sub-pixels comprises:

• a radiation absorbing layer configured to convert incident photons into electric signals;
• a plurality of comparators configured to compare the electric signals with a respective one of a plurality of reference values which have different values than each other, in order to classify the photons in a plurality of energy bands;
• and
• a plurality of counters, which have different sizes than each other and are respectively and independently connected with the plurality of comparators, configured to count and store a respective number of photons that are classified in each of the plurality of energy bands, and
• wherein a size of a first counter from among the plurality of counters is greater than a size of a second counter when a first reference value applied to a first comparator connected to the first counter from among the plurality of comparators is smaller than a second reference value applied to a second comparator connected to the second counter, and
• wherein at least one pixel comprises a plurality of unit detectors divided into at least two sub-pixel groups, the at least two sub-pixel groups including a first sub-pixel group and a second sub-pixel group and a first image pixel value in a computed tomography (CT) image is generated based on the first sub-pixel group and a second image pixel value in the CT image is generated based on the second sub-pixel group.

A computed tomography (CT) apparatus comprising:

• a radiation detector comprising a plurality of pixels, each of the plurality of pixels comprising a respective plurality of sub-pixels configured to detect radiation;
• and
• an image processor configured to reconstruct a CT image based on a number of photons detected by the radiation detector,
• wherein each of the each respective plurality of sub-pixels comprises:
• a radiation absorbing layer configured to convert incident photons into electric signals;
• a plurality of comparators configured to compare each of the electric signals with a respective one of a plurality of reference values which have different values than each other, in order to classify the photons in a plurality of energy bands;
• and
• a plurality of counters, which have different sizes than each other and are respectively and independently connected with the plurality of comparators, configured to count and store a number of photons that are classified in each of the plurality of energy bands, and
• wherein a size of a first counter from among the plurality of counters is greater than a size of a second counter when a first reference value applied to a first comparator connected to the first counter from among the plurality of comparators is smaller than a second reference value applied to a second comparator connected to the second counter, and
• wherein the image processor is further configured to generate a first image pixel value in the CT image and a second image pixel value in the CT image by dividing a second plurality of sub-pixels included in at least one pixel into at least a first sub-pixel group and a second subpixel group, wherein the at least one pixel comprises a plurality of unit detectors divided into the at least first sub-pixel group and the second sub-pixel group, and wherein the first image pixel value is generated based on the first sub-pixel group and the second image pixel value is generated based on the second sub-pixel group.

A method for using a radiation detector which includes a plurality of pixels including a plurality of unit detectors configured to detect radiation to process detected radiation, each of the plurality of unit detector including a radiation absorbing layer, a plurality of comparators, and a plurality of counters, and the method comprising:

• converting, by the radiation absorbing layer, incident photons into electric signals;
• comparing, by the plurality of comparators, each of the electric signals with a respective one of a plurality of reference values which have different values than each other, in order to classify the photons in a plurality of energy bands;
• and
• counting and storing, by the plurality of counters which have different sizes than each other and are respectively and independently connected with the plurality of comparators, a respective number of photons that are classified in each of the plurality of energy bands, and
• wherein a size of a first counter from among the plurality of counters is greater than a size of a second counter when a first reference value applied to a first comparator connected to the first counter from among the plurality of comparators is smaller than a second reference value applied to a second comparator connected to the second counter, and
• wherein at least one pixel comprises a plurality of unit detectors divided into at least two sub-pixel groups, the at least two sub-pixel groups including a first sub-pixel group and a second sub-pixel group and a first image pixel value in a computed tomography (CT) image is generated based on the first sub-pixel group and a second image pixel value in the CT image is generated based on the second sub-pixel group.

A method for using a computed tomography (CT) apparatus to generate a CT image, the CT apparatus including a radiation detector which includes at least one unit detector configured to detect radiation, each of the at least one unit detector including a radiation absorbing layer, a plurality of comparators, and a plurality of counters, and the method comprising:

• detecting, by the radiation detector, incident radiation;
• and
• generating, by an image processor, the CT image based on a number of photons detected by the radiation detector,
• wherein the detecting comprises:
• converting, by the radiation absorbing layer, incident photons into electric signals;
• comparing, by the plurality of comparators, each of the electric signals with a respective one of a plurality of reference values which have different values from each other, in order to classify the photons in a plurality of energy bands;
• and
• counting and storing, by the plurality of counters which have different sizes than each other and are respectively and independently connected with the plurality of comparators, a respective number of photons that are classified in each of the plurality of energy bands, and
• wherein a size of a first counter from among the plurality of counters is greater than a size of a second counter when a first reference value applied to a first comparator connected to the first counter from among the plurality of comparators is smaller than a second reference value applied to a second comparator connected to the second counter, and
• wherein each of the at least one unit detector comprises a pixel, and the pixel includes a respective plurality of sub-pixels, and
• wherein the generating the CT image comprises generating a first image pixel value in the CT image and a second image pixel in the CT image by dividing a corresponding plurality of sub-pixels into at least a first sub-pixel group and a second sub-pixel group, wherein the at least one pixel comprises a plurality of unit detectors divided into the at least first sub-pixel group and the second sub-pixel group, and wherein the first image pixel value is generated based on the first sub-pixel group and the second image pixel value is generated based on the second subpixel group.