Design of a prototype hybrid small animal imaging system

A proof-of-principle Single Photon Emission Imaging (SPEI) system is being constructed and validated against Geant4 Monte-Carlo simulations, with the intention of determining the optimal detector configuration for imaging the evolution of induced matastices in small animals. This device consists of a Compton-camera situated behind a mechanical modulator. The combination of mechanical and electronic (hybrid) collimation should provide optimal detection characteristics over a broad spectral range (30 keV to 511 keV), through a reduction in the sensitivity-resolution trade-off, inherent in conventional mechanically collimated configurations. The Phase I imager has been constructed from a combination of off-the-shelf detectors and custom electronics to allow the experimental architecture and data processing algorithms to be tested. This paper presents the designs and preliminary results from the simulations.