Performance of custom fine-pitch SiPM-scintillator based photon counting detectors

Photon Counting X-ray detectors attract great interest recently, which requires very high operating count rate up to 10
⁸
photons/s/mm
²
. Pixelated energy resolving detectors are necessary and greatly in interest for the use in X-ray photon-counting computed tomography (PCCT) systems. Direct detectors, such as CdTe or CdZnTe, have been successfully studied and used in clinical PCCT scanner. On the other hand, the possibility of indirect fast scintillation detectors coupled with photo-sensors has been proposed and investigated, however, the realistic fine-pitch (a few hundred micrometers pixel) SiPM-scintillator array are not demonstrated yet. In this study, we have fabricated a new custom-silicon photomultiplier (SiPM) array with the pixel size of 250 µm array (10 × 10 elements) one-to-one coupled with fine-pitch GFAG/GAGG arrays to achieve a good energy resolution and counting rate. The energy resolution shows 16.2 % at 122 keV with GAGG single pixel (20 µm device) and 18 % at 122 keV with GAGG arrays (15 µm device). GAGG shows better energy resolution than GFAG, but GFAG is promising in terms of faster response time ( <= 40 ns). Those results show the great feasibility of the indirect SiPM-scintillator based detectors for the use of X-ray PCCT. The more detail analysis and first image will be shown in the presentation.