3D Position Estimation for the AdaptiSPECT-C Modular Gamma-Ray Cameras

We are developing a single-photon emission computed tomography (SPECT) system for human brain imaging called AdaptiSPECT-C. It consists of a stationary hemisphere of 24 cameras. The system will be used for pharmacokinetic studies and drug discovery for neurodegenerative diseases. Our final camera design uses a novel light-sensor configuration that combines silicon photomultipliers (SiPMs) and photomultiplier tubes (PMTs) to improve the spatial resolution at the corners and edges of the modular camera. In this work, we have used a Monte Carlo simulation to create 3D mean detector response functions (MDRFs). We used the 3D MDRFS to estimate the 3D intrinsic spatial resolution of the cameras for our system by using the Cramer-Rao Lower Bound derived from Fisher-Information Matrices. We report on the effects of scintillation crystal edge treatments, the light yield of the crystal, and the quantum efficiency of the sensors on the intrinsic 3D spatial resolution.