Performance of custom fine-pitch indirect X-ray photon counting imager

Le résumé fourni par la source

Photon Counting X-ray detectors attract great interest recently. They requires very high operating count rate up to $10^{7}-10^{8}$ photons $/ \mathrm{s} / \mathrm{mm}^{2}$. Pixelated energy resolving detectors are necessary and greatly of interest for the use in X-ray photon-counting computed tomography (PCCT) systems. While direct detectors, such as CdTe or CdZnTe, have been successfully studied and used in clinical PCCT scanner, the possibility of indirect fast scintillation detectors coupled with photosensors has been also 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 $250 \mu \mathrm{m}$ pitch indirect photon counting detector combining a custom-silicon photomultiplier array (pitch of $250 \mu \mathrm{m}$) with finely aligned GAGG/GFAG arrays ($200 \mu \mathrm{m}$) separated with $50 \mu \mathrm{m}$ reflectors by one-to-one coupling manner. The measured imaging performance shows the separation capability of $2 \mathrm{LP} / \mathrm{mm}$ while maintaining the energy resolving capability $\sim 25 \%$ @122 keV. The characterization combining high-speed (HS)-GFAG, GFAG,GAGG with $12,15,20 \mu \mathrm{m}$ devices shows the time response (FWTM) less than 100 ns and great potential for the use in high-flux applications.

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