An Analog Decoding BGO Block Detector Using Circular Photomultipliers

This is a positron camera detector design study using quadrant sharing of circular phototubes and optically cross-coupled BGO scintillation crystals. The goal is to design a very high spatial resolution detector using the larger and less expensive circular phototubes, so that the high production cost of high spatial resolution, multi-slice positron cameras may be lowered. Theoretical calculations and experimental studies have been performed using 19mm diameter phototubes. The study shows that (a) BGO detector-pitch in the range of 2.2x2.2mm to 3.0x3.0mm (transaxial x axial) can be decoded with these 19mm diameter phototubes, and (b) it is possible to achieve very uniform signal pulse-height for all the BGO crystals in the block with this design, even though there are relatively large air-gaps between circular phototubes. This study shows that very high spatial resolution, approaching the theoretical resolution of PET imaging, can be achieved using the cheaper 19mm circular phototubes.