RESUMO
We studied the performance of a dual-panel positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation. The PET camera under development has two 10x 15 cm(2) plates that are constructed from arrays of I X 1 X 3 mm(3) LSO crystals coupled to novel ultra-thin (<200 Am) silicon position-sensitive avalanche photodiodes (PSAPD). In this design the photodetectors are configured "edge-on" with respect to incoming photons which encounter a minimum of 2 cm thick of LSO with directly measured photon interaction depth. Simulations predict that this camera will have 10-15% photon sensitivity, for an 8-4 cm panel separation. Detector measurements show approximately 1 mm(3) intrinsic spatial resolution, <12% energy resolution, and approximately 2 ns coincidence time resolution. By performing simulated dual-panel PET studies using a phantom comprising active breast, heart, and torso tissue, count performance was studied as a function of coincident time and energy windows. We also studied visualization of hot spheres of 2.5-4.0 mm diameter and various locations within the simulated breast tissue for 1 X 1 X 3 mm(3), 2 x 2 x 10 mm(3), 3 x 3 x 30 mm(3), and 4 X 4 X 20 mm(3) LSO crystal resolutions and different panel separations. Images were reconstructed by focal plane tomography with attenuation and normalization corrections applied. Simulation results indicate that with an activity concentration ratio of tumor:breast:heart:torso of 10:1:10:1 and 30 s of acquisition time, only the dual-plate PET camera comprising 1 X 1 X 3 mm(3) crystals could resolve 2.5 mm diameter spheres with an average peak-to-valley ratio of 1.3.
