A METHOD AND APPARATUS FOR VETOING RANDOM COINCIDENCES IN POSITRON EMISSION TOMOGRAPHS

摘要

Gamma ray detector and method for discriminating between "true" pairs of gamma rays produced by a single positron annihilation event (C) and those randomly occurring "pairs" of gamma rays (r) that may fall within the conventional acceptance criteria for "true" pairs. The gamma ray detector incorporates an additional array of "veto" detectors (V) arranged adjacent or around a primary detector array. The array of "veto" detectors is configured to detect gamma rays that escape detection in the primary detector array. The detection data from both the primary detector array and the veto detector array are used as inputs into a discrimination circuit for "vetoing" those pairs of gamma rays detected by the primary detector array that are likely to be the result of two or more unrelated positron annihilation events. By increasing the proportion of "true" events used in image reconstruction, the apparatus and method may improve the quality of the resulting image, reduce the image processing time and/or reduce the need for subsequent data collection and/or manipulation.