Design of a three-dimensional positron camera for nuclear medicine

Abstract

A positron camera was proposed for nuclear medical imaging of radionuclide distributions in a series of isolated planes. This 3-dimensional localization was achieved through analysis of 4 time signals, whose differences directly measure the positron (x, y and z) of individual position annihilation events. A tetrahedronal symmetry was exploited, with 2 skewed plastic scintillator bars spanning a large sensitive volume. Phototubes on each end of both bars generated fast timing pulses, uniquely determining the decay position through a time-of-flight technique. The mathematical properties of the transformation from the observed quantities to the spatial distribution of the radionuclide were investigated. A discussion of the efficiency of the system and the effects of Compton scattering in tissue was given. A 1-dimensional pilot study encouraged the development of the prototype 3-dimensional positron camera.