Coincidence determination method and apparatus of PET device

A coincidence determination apparatus of a PET device comprising:

• a PET device configured to use a scintillator of radioactive isotope containing background noise due to intrinsic radioactivity as a radiation detector;
• a determination unit configured to determine a coincidence using a wide energy window,
• a setting unit configured to set a lower limit value and an upper limit value of the wide energy window, the wide energy window allowing detection of the background noise due to intrinsic radioactivity as multiple coincidences when pairs of annihilation radiations assumed to occur from a same nuclide are counted, the annihilation radiations being detected within a predetermined coincidence time window by a plurality of radiation detectors;
• a removal unit configured to remove the multiple coincidences caused by the background noise;
• and
• a limiting unit configured to use a narrow energy window narrower than the wide energy window to limit a coincidence event to a coincidence event in a photopeak from a positron nuclide only.