Digital positron emission tomography (DPET) energy calibration method

A system for energy correction of positron emission tomography (PET) event data, said system comprising:

• a plurality of solid state detector modules detecting gamma photons from a region of interest of a patient and generating the event data in response to the gamma photons;
• at least one energy correction processor programmed to:
• receive event data for a plurality of strike events corresponding to gamma events, each strike event detected by a pixel of a detector module and including an energy and a time,
• linearize the energy of the strike events using an energy linearity correction model including one or more parameters,
• identify clusters of the strike events based on the times of the strike events,
• identify sub-clusters of the clusters based on the pixels corresponding to the strike events of the clusters,
• correct energies of the sub-clusters using a first set of correction factors, and,
• correct energies of clusters including a plurality of sub-clusters using a second set of correction factors;
• and,
• a reconstruction processor processing the event data as corrected by the energy correction processor to create an image representation of the region of interest.

A method for energy correction of positron emission tomography (PET) event data, said method comprising:

• receiving by at least one processor event data for a plurality of strike events corresponding to 511 keV gamma photons from a region of interest of a patient disposed in an imaging volume of a PET scanner, each of the strike events being detected by a pixel of a detector module and including an energy and a time, individual ones of the 511 keV gamma photons being scattered in a scintillation crystal of a first detector, the scattering causing a first portion of the 511 keV gamma photon to be converted to light in a first strike event and a remainder of the gamma photon to travel into a scintillation crystal of an adjoining detector converting a second portion of the gamma photon to light in a second strike event;
• linearizing by the at least one processor the energy of the strike events of the event data using an energy linearity correction model including one or more parameters;
• identifying by the at least one processor clusters of the strike events based on the times of the strike events, each cluster corresponding to the strike events caused by a single 511 keV gamma photon;
• identifying by the at least one processor sub-clusters of the clusters based on the pixels corresponding to the strike events of the clusters;
• correcting by the at least one processor energies of the strike events of the sub-clusters of the event data using a first set of correction factors;
• and,
• further correcting by the at least one processor energies of the strike events of each cluster including a plurality of sub-clusters of the event data using a second set of correction factors;
• reconstructing the linearized and corrected event data into an image depicting the region of interest of the patient;
• and,
• displaying the image with a display device.

A positron emission tomography (PET) system with energy correction of positron emission tomography (PET) event data, said system comprising:

• a ring of gamma photon detectors, each gamma photon detector including a scintillator which converts gamma energy into light scintillations and light radiation sensitive elements which convert each light scintillation into event data, the ring of gamma photon detectors encircling an imaging volume configured to receive 511 keV gamma photons from a region of interest of a patient, each 511 keV photon striking a scintillator being a gamma event;
• wherein each 511 keV gamma photon strikes a first scintillation crystal causing a first scintillation and is scattered into a second scintillation crystal causing a second scintillation, the output from each light radiation sensitive element in response to a scintillation being a strike event, the plurality of strike events corresponding to a single 511 keV gamma event being a cluster;
• at least one processor programmed to:
• receive the event data for a plurality of the strike events corresponding to each gamma event, each strike event detected by a pixel of a detector module and including an energy and a time;
• linearize the energy of the strike events between 100 keV and 500 keV using an energy linearity correction model;
• identify the clusters of the strike events based on the times of the strike events;
• correct energies of the strike events of sub-clusters of the identified clusters using a first level of clustering energy correction factors;
• correct the energies of the strike events corresponding to each cluster using second level clustering energy correction factors;
• combine the corrected energies of the strike events of a common cluster;
• compare the combined corrected energies with a preselected threshold;
• and
• reconstruct the clusters with combined energies exceeding the preselected threshold into a PET image of the region of interest.