# US 10,117,628 B2 · Photon counting apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,117,628 B2 - Document ID: US10117628B2 - Status: Granted - Kind: B2 - Application number: 14/870,386 - Filed: 2015-09-30 - Published: 2016-04-07 - Granted: 2018-11-06 - Earliest claimed: 2014-10-01 - Assignees: Toshiba Medical Systems Corporation - Applicants: Toshiba Medical Systems Corporation - Inventors: Emi Tamura - Web page: https://patentgrep.com/patent/US10117628B2 ## CPC - A61B 6/482: {involving multiple energy imaging} - A61B 6/032: {Transmission computed tomography [CT]} - A61B 6/4035: {the source being combined with a filter or grating} - A61B 6/42: Arrangements for detecting radiation specially adapted for radiation diagnosis - A61B 6/4233: {using matrix detectors} - A61B 6/4241: {using energy resolving detectors, e.g. photon counting} - A61B 6/5205: {involving processing of raw data to produce diagnostic data} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract According to one embodiment, the X-ray tube generates X-rays. The X-ray detector detects the X-rays transmitted through a subject. The data acquisition circuitry acquires count data concerning a count number of the detected X-rays for energy bands. The memory circuitry stores data of a response function that associates incident X-rays on the X-ray detector with a response characteristic of a system including the X-ray detector and the data acquisition circuitry. The processing circuitry calculates an X-ray absorption amount of each of a plurality of base substances based on the count data concerning the energy bands acquired by the data acquisition circuitry, an energy spectrum of the incident X-rays, and the response function. ## Claims ### Claim 1 A photon counting apparatus, comprising: an X-ray tube configured to generate X-rays; an X-ray detector configured to detect the X-rays generated by the X-ray tube and transmitted through a subject; data acquisition circuitry configured to acquire count data concerning a count number of the detected X-rays for a plurality of energy bands, based on an output signal from the X-ray detector; memory circuitry configured to store data of a response function that associates an energy of incident X-rays on the X-ray detector with a response characteristic of a system including at least one of the X-ray detector and the data acquisition circuitry; and processing circuitry configured to calculate an X-ray absorption amount of each of a plurality of base substances based on the count data concerning the plurality of energy bands acquired by the data acquisition circuitry, an energy spectrum of the incident X-rays generated by the X-ray tube, and the data of the response function stored in the memory circuitry. ### Claim 2 (depends on 1) The photon counting apparatus according to claim 1, where the processing circuitry is further configured to reconstruct an image based on the X-ray absorption amount of each of the plurality of base substances. ### Claim 3 (depends on 1) The photon counting apparatus according to claim 1, where the processing circuitry is further configured to calculate a difference between the count data and a model function representing an energy spectrum of X-rays transmitted through the subject while changing an X-ray absorption amount of each of the plurality of base substances included in the model function that describes the response characteristic of the system, and decide a final X-ray absorption amount of each of the plurality of base substances with which the difference becomes smaller than a predetermined value. ### Claim 4 (depends on 3) The photon counting apparatus according to claim 3, where the model function is defined by convolution of the response function for an integrated value of the energy spectrum of the incident X-rays generated by the X-ray tube and a power of a Napier's constant using the X-ray absorption amount as an exponent. ### Claim 5 (depends on 3) The photon counting apparatus according to claim 3, where the X-ray absorption amount of each of the plurality of base substances is defined by a product of an X-ray attenuation coefficient and a transmission path length of each of the plurality of base substances. ### Claim 6 (depends on 3) The photon counting apparatus according to claim 3, where the processing circuitry is further configured to decide the final X-ray absorption amount with which the difference becomes smaller than the predetermined value simultaneously for all of the plurality of energy bands. ### Claim 7 (depends on 3) The photon counting apparatus according to claim 3, where the processing circuitry is further configured to decide the final X-ray absorption amount on a view basis. ### Claim 8 (depends on 1) The photon counting apparatus according to claim 1, further comprising an X-ray filter configured to attenuate the X-rays generated by the X-ray tube, wherein the energy spectrum of the incident X-rays generated by the X-ray tube is an energy spectrum of X-rays that enter the subject through the X-ray filter. ### Claim 9 (depends on 1) The photon counting apparatus according to claim 1, wherein the response function defines a relationship between detection energy and an output response for each energy of the X-rays. ### Claim 10 (depends on 9) The photon counting apparatus according to claim 9, wherein the response function expresses a main peak corresponding to the energy of the X-rays from the X-ray tube. ### Claim 11 (depends on 10) The photon counting apparatus according to claim 10, wherein the X-ray tube includes an anode target, and the response function expresses the main peak, characteristic X-rays originated from the anode target of the X-ray tube, and an escape peak corresponding to energy lower than the energy of the X-rays from the X-ray tube by the energy of the characteristic X-rays. ### Claim 12 (depends on 1) The photon counting apparatus according to claim 1, wherein the processing circuitry is further configured to generate the response function in advance based on an output of the X-ray detector for each of a plurality of monochromatic X-rays. ### Claim 13 (depends on 1) The photon counting apparatus according to claim 1, wherein the plurality of energy bands comprise at least 16 energy bands, and the data acquisition circuitry is further configured to acquire the count data for the at least 16 energy bands. ### Claim 14 (depends on 1) The photon counting apparatus according to claim 1, wherein the data acquisition circuitry further comprises: discrimination circuitry configured to discriminate an analog output signal from the X-ray detector to the plurality of energy bands based on a peak value of the analog output signal from the X-ray detector; and counting circuitry configured to generate the count data for the plurality of energy bands based on an output signal from the discrimination circuitry. ### Claim 15 (depends on 1) The photon counting apparatus according to claim 1, wherein the data acquisition circuitry further comprises: conversion circuitry configured to convert an analog output signal from the X-ray detector into a digital signal; discrimination circuitry configured to discriminate the digital signal from the conversion circuitry to the plurality of energy bands based on a data value of the digital signal from the conversion circuitry; and counting circuitry configured to generate the count data for the plurality of energy bands based on an output signal from the discrimination circuitry. ### Claim 16 (depends on 1) The photon counting apparatus according to claim 1, wherein the X-ray detector further comprises a phosphor configured to convert X-rays into fluorescence, and a photodetector configured to convert the fluorescence into an output signal. ### Claim 17 (depends on 1) The photon counting apparatus according to claim 1, wherein the X-ray detector further comprises a semiconductor configured to convert X-rays into electron-hole pairs, and electrodes provided at two ends of the semiconductor and configured to convert the electron-hole pairs into an output signal. ### Claim 18 (depends on 1) The photon counting apparatus according to claim 1, wherein the memory circuitry stores the data of the response function that associates energy of incident X-rays on the X-ray detector with a response characteristic of both of the X-ray detector and the data acquisition circuitry. ### Claim 19 An image generating apparatus, comprising: memory circuitry configured to store data of a response function that associates energy of incident X rays on an X ray detector with a response characteristic of a system including at least one of the X ray detector and data acquisition circuitry; and processing circuitry configured to acquire count data concerning a count number of X rays for a plurality of energy bands; and calculate an X ray absorption amount of each of a plurality of base substances based on the count data concerning the plurality of energy bands acquired by the data acquisition circuitry, an energy spectrum of the incident X rays generated by an X ray tube, and the data of the response function stored in the memory circuitry.