A high speed position-decoding electronics for BGO block detectors in PET

A high-speed prototype electronics for positioning gamma event at EGO block detectors in PET has been developed. It adapts the "high-yield pileup-event recovery" method (HYPER) proposed by the authors for nonimaging probes and gamma camera. HYPER uses recurring residual subtractions for multiple/continuous pileup conditions. The regular Anger positioning algorithm was modified by the HYPER method. The HYPER-Anger positioning circuit was designed for individual EGO blocks or block arrays and tested on a EGO block (2/spl times/2 cm with 7/spl times/7 elements on 4 PMT). The block was well decoded even at 800 kcps, which is 6-7/spl times/ higher than the typical maximum rate of 130 kcps for EGO blocks. The position-decoding electronics may be used to increase the maximum imaging-rate of regular EGO PET or to compensate for the lower imaging rate of the PMT-quadrant-sharing detector design, which doubles spatial resolution in both transaxial and axial directions.