Method and apparatus for automatic detection and correction of patient bed shift using intrinsic scintillation crystal radiations

A method for operating an imaging system, the imaging system comprising a positron emission tomography (PET) scanner, the PET scanner including a bed being positioned within a bore of a detector assembly, and the detector assembly including a plurality of scintillator crystals enclosing the bore, the method comprising:

• obtaining a plurality of reference sinograms acquired based on blank scan data corresponding to a first energy level, wherein the blank scan data originate from intrinsic background radiation of the plurality of scintillator crystals at a plurality of predetermined bed locations of the bed on which a nonradioactive phantom of a first weight is placed, each of the plurality of reference sinograms corresponding to one of the plurality of predetermined bed locations;
• acquiring emission data of gamma photons of multiple energy levels originating from intrinsic background radiation and annihilation events associated with radioactivity of a patient on the bed;
• and
• differentiating, from the acquired emission data of gamma photons of multiple energy levels, emission data relating to the intrinsic background radiation from emission data emitted by the patient;
• generating a measured sinogram based on the differentiated emission data relating to the intrinsic background radiation;
• and
• comparing the measured sinogram with the plurality of reference sinograms to determine a bed shift of the bed.

An imaging system, comprising:

• a positron emission tomography (PET) scanner, the PET scanner including:
• a detector assembly including a plurality of scintillator crystals;
• a bed adapted to be accommodated in a bore enclosed by the plurality of scintillator crystals;
• at least one storage medium including a set of instructions;
• and
• at least one processor configured to communicate with the at least one storage medium, wherein when executing the set of instructions, the system is configured to:
• obtain a plurality of reference sinograms acquired based on blank scan data corresponding to a first energy level, wherein the blank scan data originate from intrinsic background radiation of the plurality of scintillator crystals at a plurality of predetermined bed locations of the bed on which a nonradioactive phantom of a first weight is placed, each of the plurality of reference sinograms corresponding to one of the plurality of predetermined bed locations;
• acquire emission data of gamma photons of multiple energy levels originating from intrinsic background radiation and annihilation events associated with radioactivity of a patient on the bed;
• and,
• differentiate, from the acquired emission data of gamma photons of multiple energy levels, emission data relating to the intrinsic background radiation from the radioactivity from the patient;
• generate a measured sinogram based on the differentiated emission data relating to the intrinsic background radiation;
• and
• compare the measured sinogram with the plurality of reference sinogram to determine a bed shift of the bed.