A 32-channel LSO matrix coupled to a monolithic 4/spl times/8 APD array for high resolution PET

Summary form only given as follows: Avalanche Photodiodes (APD) offer new design options for high resolution PET detectors. New, monolithic arrays of 4/spl times/8 densely packed APDs (each with a 1.6 mm/spl times/1.6 mm sensitive area) were developed and evaluated for their suitability to read out 32 small (2 mm/spl times/2 mm/spl times/6 mm) LSO crystals. The gain of the APDs was about 10, its variation within an array was less than 9%. The average dark current was 8 nA per diode pixel, the detector capacitance was 10...12 pF. Energy resolution was 16.6% for gamma rays with 511 keV. In the matrix of 32 crystals coupled to the APD array, light crosstalk was only 8%. The monolithic APD arrays proved to be stable and may, in combination with LSO crystals, facilitate the design of various detector geometries, such as panels or multi-layer modules.