Patent ID: 7274021

Claim:
A coincidence counting method of γ rays in a nuclear medicine diagnostic apparatus for creating a functional image by processing detection signals of γ rays output from a plurality of detectors for detecting γ rays, comprising the steps of: measuring detection times of γ rays on the basis of said detection signals of γ rays output from said detectors; determining energies of γ rays on the basis of said detection signals of γ rays; calculating a difference of said energies determined between a first detected γ ray and a subsequently detected γ ray which are subject to coincidence counting; setting a time window for a coincidence counting on the basis of the difference of said energies; calculating a difference between a detection time of said first detected γ ray and a detection time of said subsequently detected γ ray; and executing a coincidence counting in comparison with a width of said time window set and said difference between said detection times.