Method for reducing an electronic time coincidence window in positron emission tomography

A method of acquiring PET images of a patient comprising:

• obtaining a preliminary image of a patient;
• describing a spatial location of said patient using said preliminary image;
• for each line of response connecting a pair of oppositely disposed PET detectors, calculating a time coincidence window based on an intersection of said described spatial location with said line of response;
• detecting a pair of gamma photons produced by an annihilation event;
• determining whether the detection of said pair of gamma photons occurs within the calculated time coincidence window corresponding to a line of response of said annihilation event;
• accepting data relative to the detection of said pair of gamma photons only if the detection of said gamma photons occurs within said time coincidence window;
• calculating a spatial location of said annihilation event only if the annihilation event has been accepted;
• and,
• adding the calculated spatial location of said annihilation event to a stored distribution of calculated annihilation event spatial locations representing the radioactivity distribution in said patient.