3-D photon impact determination using fitting approaches to the Light Distribution

In Positron Emission Tomography (PET) detectors based in monolithic scintillators, the spatial resolution is limited by the accuracy in the determination of the interaction coordinates from the 511 keV photons. When linear algorithms, such as Center of Gravity (CoG) are used a poor estimation of the interaction positions, specially towards the edges is the major limitation in spatial resolution. A novel PET detector block, where complete information of Light Distribution (LD) for each event is available, allows to fit each event to a theoretical model, improving the estimation of the interaction coordinates, and minimizing border effects. In this work, by means of the LD fitting approach, we were able to obtain an average spatial resolution of 1.2 mm in the entire scintillator volume and an average depth of interaction (DOI) resolution of 1.5 mm. Moreover, splitting the data in three DOI regions, we obtained an average spatial resolution of 1.0 mm at the DOI region closer to the photodetectors. Finally, it is remarkable that the implementation of the LD fitting approach is capable of processing up to 50 kcps in a octacore system.