Robert J. Nickles

DESIGN OF A THREE-DIMENSIONAL POSITRON CAMERA FOR NUCLEAR MEDICINE

A positron camera is proposed for nuclear medical imaging of radionuclide distributions in a series of isolated planes. This three-dimensional localisation is achieved through analysis of four time signals, whose differences directly measure the position (x, y, z) of individual positron annihilation events. A tetrahedronal symmetry is exploited, with two skewed plastic scintillator bars spanning a large sensitive volume. Phototubes on each end of both bars generate 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 are investigated. A discussion of the efficiency of the system and the effects of Compton scattering in tissue is given. A one-dimensional pilot study encourages the development of the prototype three-dimensional positron camera.

Use of a generalized modular data handling system in nuclear medicine.

Addition of a CAMAC modular data handling system to a small computer used for gamma-camera work has allowed the acquisition and processing of a broad variety of nuclear medicine data. Significant contributions have been made ranging from clinical renal evaluation to radiopharmaceutical development. Digital rectilinear scanning and computer acquisition of physiological signals such as the electrocardiogram are other applications. The system provides an inexpensive means of matching present-day nuclear computers to the diversity of data.