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US 11,707,243 B2Granted
Scatter and random coincidence rejection
AssigneeCanon Medical Systems Corporation
InventorsLiang Cai, Wenyuan Qi, Xiaochun Lai, Peng Peng
Life of this patent
Estimating the term…
Abstract
Multiple interactions, such as Compton scattering, inside a PET detector are used to predict an incident photon's direction for identifying true coincidence events versus scatter/random coincidence events by creating a cone shaped shell projection defining a range of possible flight directions for the incident photon. The disclosed techniques can be used as prior information to improve the image reconstruction process. The disclosed techniques can be implemented in a LYSO/SiPM-based layer stacked detector, which can precisely register multiple interactions' 3D position.
Claims20
A nuclear medical diagnostic apparatus, comprising:
- first and second gamma ray detectors for detecting first and second annihilation gamma rays, respectively;
- processing circuitry configured to
- identify a possible coincidence event between the first gamma ray detector and the second gamma ray detector;
- estimate a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- determine whether the second gamma ray detector is located within the estimated range of possible flight directions;
- and
- count the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is located within the range of possible flight directions, and not count the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is not located within the range of possible flight directions.
4 more elements
A method for collecting coincidence data in a nuclear medical diagnostic apparatus having a first and second gamma ray detector for detecting first and second annihilation gamma rays, respectively, the method comprising:
- identifying a possible coincidence event between the first gamma ray detector and the second gamma ray detector;
- estimating a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- determining whether the second gamma ray detector is located within the estimated range of possible flight directions;
- and
- counting the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is located within the range of possible flight directions, and not counting the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is not located within the range of possible flight directions.
2 more elements
A non-transitory computer-readable medium including computer-readable instructions that, when executed by a computing system, cause the computing system to perform a method comprising:
- identifying a possible coincidence event between a first gamma ray detector for detecting a first annihilation gamma ray and a second gamma ray detector for detecting a second annihilation gamma ray;
- estimating a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- determining whether the second gamma ray detector is located within the estimated range of possible flight directions;
- and
- counting the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is located within the range of possible flight directions, and not counting the possible coincidence event as a true coincidence event when determining that the second gamma ray detector is not located within the range of possible flight directions.
2 more elements
A nuclear medical diagnostic apparatus, comprising:
- first and second gamma ray detectors for detecting first and second annihilation gamma rays, respectively;
- processing circuitry configured to
- identify a possible coincidence event between the first gamma ray detector and the second gamma ray detector;
- estimate a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- and
- count the possible coincidence event as a true coincidence event when the second gamma ray detector is located within the range of possible flight directions, and not count the possible coincidence event as a true coincidence event when the second gamma ray detector is not located within the range of possible flight directions,
- wherein the processing circuitry is further configured to:
- determine a first range of possible flight directions for the first annihilation gamma ray based on a location of the Compton scatter event detected by the first gamma ray detector and an energy of the Compton scatter event detected by the first gamma ray detector, and
- expand the determined first range so as to determine, as the estimated range, a second range larger than the first range, the second range being determined based on a spatial resolution of the detected location and an energy resolution of the detected energy.
6 more elements
A method for collecting coincidence data in a nuclear medical diagnostic apparatus having a first and second gamma ray detector for detecting first and second annihilation gamma rays, respectively, the method comprising:
- identifying a possible coincidence event between the first gamma ray detector and the second gamma ray detector;
- estimating a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- and
- counting the possible coincidence event as a true coincidence event when the second gamma ray detector is located within the range of possible flight directions, and not counting the possible coincidence event as a true coincidence event when the second gamma ray detector is not located within the range of possible flight directions, wherein the method further comprises:
- determining a first range of possible flight directions for the first annihilation gamma ray based on a location of the Compton scatter event detected by the first gamma ray detector and an energy of the Compton scatter event detected by the first gamma ray detector, and
- expanding the determined first range so as to determine, as the estimated range, a second range larger than the first range, the second range being determined based on a spatial resolution of the detected location and an energy resolution of the detected energy.
3 more elements
A non-transitory computer-readable medium including computer-readable instructions that, when executed by a computing system, cause the computing system to perform a method comprising:
- identifying a possible coincidence event between a first gamma ray detector for detecting a first annihilation gamma ray and a second gamma ray detector for detecting a second annihilation gamma ray;
- estimating a range of possible flight directions for the first annihilation gamma ray detected by the first gamma ray detector based on a Compton scatter event, which is detected by the first gamma ray detector, wherein the possible coincidence event includes the Compton scatter event detected by the first gamma ray detector;
- and
- counting the possible coincidence event as a true coincidence event when the second gamma ray detector is located within the range of possible flight directions, and not counting the possible coincidence event as a true coincidence event when the second gamma ray detector is not located within the range of possible flight directions, wherein the method further comprises:
- determining a first range of possible flight directions for the first annihilation gamma ray based on a location of the Compton scatter event detected by the first gamma ray detector and an energy of the Compton scatter event detected by the first gamma ray detector, and
- expanding the determined first range so as to determine, as the estimated range, a second range larger than the first range, the second range being determined based on a spatial resolution of the detected location and an energy resolution of the detected energy.
3 more elements
Dependencies are inferred from the claim text.