Method and apparatus for vetoing random coincidences in positron emission tomographs

A method for determining the position of a plurality of positron annihilation events within scanned matter comprising:

• arranging the scanned matter within a primary detector array;
• arranging a veto detector array adjacent the primary detector array;
• detecting a plurality of coincident gamma ray pairs at a plurality of valid primary detector pairs;
• evaluating random gamma ray detection by the veto detector array during coincident time periods corresponding to the coincident gamma ray pairs;
• and
• transferring data corresponding to coincident gamma ray pairs detected during coincident time periods during which no random gamma ray was detected by the veto detector array.

An apparatus for determining the position of a plurality of positron annihilation events within scanned matter comprising:

• an open area for receiving at least a portion of the scanned matter, wherein a plurality of gamma ray pairs are generated within the scanned matter as a result of positron annihilation events;
• a primary detector array arranged at least partially around the open area for detecting a first portion of the plurality of coincident gamma ray pairs, the first portion including both true pairs and false pairs resulting from a pair of randoms events;
• a veto detector array arranged adjacent the primary detector array and the open area for detecting a second portion of the plurality of gamma ray pairs, wherein the second portion includes primarily gamma rays corresponding to the pair of randoms events;
• and
• a discriminator logic circuit for transferring detection data from the primary detector array corresponding to coincident gamma ray pairs detected during coincident time periods during which no gamma rays were detected by the veto detector array.

An apparatus for determining the position of a plurality of positron annihilation events within scanned matter comprising:

• an open area for receiving at least a portion of the scanned matter, wherein a plurality of gamma ray pairs are generated within the scanned matter as a result of positron annihilation events;
• a primary detector array is arranged in a ring configuration surrounding the open area for detecting a first portion of the plurality of coincident gamma ray pairs, the first portion including both true pairs and false pairs resulting from a pair of randoms events;
• a veto detector array including a plurality of detectors arranged to encompass, substantially completely, both the primary detector array and the open area for detecting a second portion of the plurality of gamma ray pairs, wherein the second portion includes primarily gamma rays corresponding to the pair of randoms events;
• and
• a discriminator logic circuit for transferring detection data from the primary detector array corresponding to coincident gamma ray pairs detected during coincident time periods during which no gamma rays were detected by the veto detector array.