Performance of large BGO arrays coupled to SiPM photosensors — Continued study

Abstract

Recently, several studies have been carried in order to determine potential capabilities of BGO scintillator crystals coupled to SiPM photosensor devices for PET and SPECT applications. The prior studies have been typically done on small size BGO samples. Despite the fact that timing capabilities for devices based on BGO are worse than those based in commonly used fast scintillators, such as LYSO and LSO, the price of BGO material is considerably lower and, thus, BGO could be an option for systems where the required scintillator volume is significantly higher. In this report we present results of further studies using 12×12 SiPM arrays of the 3 mm C-Series SensL sensors, placed at a pitch of 4.2 mm, and coupled to the readout recording the 12 row and 12 column SiPM array signals. Two types of pixellated BGO crystals were tested: an array of 10×10 elements with 2.5 mm pitch and 10 mm thickness and an array of 30×30 pixels with 1.67 mm pitch but only 3 mm thick. A staggered depth-of-interaction (DOI) configuration was also evaluated using two layers of 2.5 mm pitch BGO pixels, with 10×10 (top) and 11×11 (bottom) elements with a total thickness of 20 mm. An energy resolution as good as 12% FWHM has been obtained. Our new results confirm that either single layer crystal arrays with pitch values as low as 1.67 mm or two staggered layers of 2.5 mm pitch could be well suited for PET applications, especially for large systems or low cost dedicated PET systems.