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 substantially lowered. Theoretical calculations and experimental studies have been performed using 19 mm diameter phototubes. The study shows that (a) BGO detector-pitch in the range of 2.7×2.7 mm to 3.0×3.0 mm (transaxial×axial) can be decoded with these 19 mm diameter phototubes, and (b) it is possible to achieve relatively uniform light-collection efficiency for all the BGO crystals in the block with this design, even though there are relatively large air-gaps between circular phototubes. This study demonstrates that very high spatial resolution, approaching the theoretical resolution of PET imaging, can be achieved at a substantially lower cost than that of current commercial PET detector designs