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-even t recovery" method (HYPER) proposed by us for nonimaging probes and gamma c amera. HYPER uses recurring residual subtractions for multiple/continuous p ileup conditions. The regular Anger positioning algorithm was modified by t he HYPER method. The HYPER-Anger positioning circuit was designed for indiv idual EGO blocks or block arrays and tested on a EGO block (2x2 cm with 7x7 elements on 4 PMT). The block was well decoded even at 800 kcps, which is 6-7x higher than the typical maximum rate of 130 kcps for EGO blocks. The p osition-decoding electronics may be used to increase the maximum imaging-ra te of regular EGO PET or to compensate for the lower imaging rate of the PM T-quadrant-sharing detector design, which doubles spatial resolution in bot h transaxial and axial directions.