POSITRON TOMOGRAPH USING OPTICALLY COUPLED DETECTORS

IT HAS BEEN DEMONSTRATED THAT A HIGH-RESOLUTION POSITRON EMISSION TOMOGRAPH CAN BE CONSTRUCTED USING SIX LARGE-AREA POSITION-SENSITIVE SODIUM IODIDE (NAI(TI)) SCINTILLATION DETECTORS. THIS RESEARCH ADDRESSES A BASIC MODIFICATION TO THE DETECTION SYSTEM THAT WILL RESULT IN SIGNIFICANT PERFORMANCE IMPROVEMENTS AND A REDUCED SYSTEM COST. SPECIFICALLY, IT IS PLANNED TO OPTICALLY COUPLE THE SYSTEM'SDETECTORS, ENABLING SCINTILLATION LIGHT TO BE SHARED BY NEIGHBORING DETECTORS. THIS ELIMINATES THE SHARP BOUNDARIESBETWEEN DETECTORS, WHICH WILL REDUCE THE SIZE OF THE EFFECTIVE GAP BETWEEN DETECTORS, RESULTING IN IMPROVED IMAGE QUALITY. THIS SHOULD ALSO PERMIT SUBSTITUTION OF A REDUCED NUMBER OF LARGER ROUND PHOTOMULTIPLIERS FOR THE CURRENT RECTANGULAR ARRAY OF THE MORE EXPENSIVE SQUARE PHOTOMULTIPLIERS. PHASE I EFFORTS WILL INVESTIGATE TECHNIQUES FOR OPTICALLY COUPLING THE DETECTORS, TECHNIQUES FOR POSITION ESTIMATION NEAR THE BOUNDARIES OF TWO OPTICALLY COUPLED DETECTORS, AND THE ADAPTATION OF THE EVENT-TRIGGERING SYSTEM FOR USE WITH OPTICALLY COUPLED DETECTORS. PHASE II RESEARCH WILL CONCENTRATE ON INCORPORATING THE OPTICALLY COUPLED DETECTOR SYSTEM INTO A TOMOGRAPH.