Design considerations and construction of a small animal PET prototype

We are developing a small animal PET scanner consisting of two block detectors, each made of 216 BGO crystals of dimensions 3.75 mm×3.75 mm×20 mm, cylindrically arranged and coupled to a position-sensitive photomultiplier tube (R2486 PSPMT). Our design was based on a very detailed Monte Carlo, that simulates the function of a PET scanner from the system level down to the individual γ-ray detectors. We have made laboratory measurements of the individual detector performance as well as measurements of characteristics of the PSPMTs. The two detector blocks which will form the basic tomographic unit have been assembled. We are developing electronics to individually process (amplify and digitize) anode signals, and use field programmable gate arrays (FPGAs) in the position determination and energy measurement of the γ-rays. At present, as an intermediate step, we are using the electronics supplied from Hamamatsu to study various aspects of the system and produce initial images.