Feasibility study on TOF-PET with fill factor improved SiPMs

Due to the uncertainty of the annihilation event’s position along a given line-of-response (LOR), there is a large amount of statistical noise that is inherent to conventional PET image reconstruction. To overcome the poor spatial resolution of PET, time-of-flight positron emission tomography (TOF-PET) has been suggested. The use of the time-of-flight PET provides significant improvements to the image quality and 3 dimensional imaging. In this study, 2×2mm2 SiPMs, operated in the Geiger avalanche mode, were designed and fabricated on epitaxial silicon wafers. Fabricated SiPMs whose doping structure is N+/P/π/P+, have a high geometric fill-factor with quenching resistors of the high resistive poly-silicon layer and a high sensitivity to short-wavelength light with the shallow-junction. Fundamental characteristics of SiPM were measured and analyzed. Achievable timing resolution was investigated and quantified with a LYSO crystal and SiPMs.