Monte Carlo simulation study of a dual-plate PET camera dedicated to breast cancer imaging

We studied the performance of a dual-plate positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation based on GATE open code software. The PET camera under development has two 10times15 cm² plates that are constructed from arrays of 1times1times3 mm³ LSO crystals coupled to novel silicon-based ultra-thin (<300 mum) position-sensitive avalanche photodiodes (PSAPD). With the photodetector configured "edge-on", incoming photons see effectively 2-cm-thick of LSO with directly measured 3-mm photon depth-of-interaction. Simulations predict that this camera will have >10% sensitivity, and detector measurements show ~1 mm³ intrinsic spatial resolution, <12% energy resolution, and ~2 ns coincidence time resolution. With a breast phantom including breast, heart and torso activity (concentration ratio of 1:10:1, respectively), count performance was studied under varying time and energy windows. We also studied visualization of hot spheres within the breast for 1times1times3 mm³, 2times2times10 mm³, 3times3times30 mm³ and 4times4times20 mm³ crystal resolutions at different plate separations. Images were reconstructed by focal plane tomography and 3D OS-EM with attenuation and solid angle corrections applied. With an activity concentration ratio of tumor:breast:heart:torso of 10:1:10:1, only the dual-plate PET camera comprising 1times1times3 mm³ crystals can resolve 2.5-mm tumor spheres with an average peak-to-valley ratio of 1.3 in only 30 seconds of acquisition time