Radiation detection device, radiation diagnostic device, radiation detection method, and computer program product
A radiation detection device according to an embodiment includes a scintillator and a processing circuit. The processing circuit measures transferred energy when scintillation is caused after a gamma ray incident on a scintillator generates Cherenkov light and estimates a Cherenkov angle based on the transferred energy.
1. A radiation detection device comprising:
a scintillator;
a detector configured to detect a first light corresponding to Cherenkov light generated by incidence of a gamma ray into the scintillator and a second light generated after the first light has been generated by incidence of the gamma ray into the scintillator; and
a processing circuit configured to
measure transferred energy based on a detection result of the second light detected by the detector, the transferred energy corresponding to energy of the second light when scintillation by which the second light is generated is caused,
estimate a Cherenkov angle based on the transferred energy, and
specify a radiation position corresponding to a position where the first light is generated based on the estimated Cherenkov angle and a position on the detector where the first light is detected.
2. The radiation detection device according to claim 1 , wherein the processing circuit is configured to
acquire pieces of position distribution information on Cherenkov events detected when the first light is generated,
specify a radiation point of the first light based on the Cherenkov angle,
estimate a number of generated Cherenkov photons based on a detector output signal after the gamma ray is incident on the scintillator, and
acquire the position distribution information based on an estimated number of Cherenkov photons.
3. The radiation detection device according to claim 2 , wherein the processing circuit is configured to
acquire pieces of position distribution information on Cherenkov events detected when the Cherenkov light is generated, and
specify a radiation point of the Cherenkov light based on the Cherenkov angle and the position distribution information.
4. The radiation detection device according to claim 2 , wherein the processing circuit is configured to acquire the position distribution information by specifying the Cherenkov events to be acquired based on time information.
5. The radiation detection device according to claim 2 , wherein the processing circuit is configured to estimate the number of Cherenkov photons by performing fitting the detector output signal as a function of time to a theoretical curve, and is configured to measure the transferred energy based on a result of the fitting.
6. The radiation detection device according to claim 2 , wherein the processing circuit is configured to estimate the number of Cherenkov photons based on the detector output signal in a period from an estimated time of a time at which the first light is generated to a first time, and is configured to measure the transferred energy based on the detector output signal on or after the first time.
7. The radiation detection device according to claim 2 , wherein the processing circuit is configured to specify an incident direction of the gamma ray based on the specified radiation point of the first light.
8. The radiation detection device according to claim 2 , wherein the processing circuit is configured to remove or correct a line of response (LOR) due to scattering of a pair of annihilation gamma rays based on the specified radiation point of the first light.
9. A radiation detection method comprising:
detecting, by a detector, a first light corresponding to Cherenkov light generated by incidence of a gamma ray into a scintillator and a second light generated after the first light has been generated by incidence of the gamma ray into the scintillator,
measuring transferred energy based on a detection result of the second light detected, the transferred energy corresponding to energy of the second light when scintillation by which the second light is generated is caused,
estimating a Cherenkov angle based on the transferred energy, and
specifying a radiation position corresponding to a position where the first light is generated based on the estimated Cherenkov angle and a position on the detector where the first light is detected.