a system for multiplexing photodetector signals from a scintillation detector . the system includes a detector module having a number of scintillator blocks , each scintillator block having a number of photosensors , and a number of multiplexing circuits . each multiplexing circuit includes a number of inputs , a signal polarity inverter and at least one differential output attached to the signal polarity inverter . the multiplexing system inverts the polarity of preselected signals from the photosensors and selectively combines signals of different polarities to calculate event positioning and total energy .