Cherenkov Light Emission in Pure Cherenkov Emitters for Prompt Gamma Imaging.

Proton range verification (PRV) in proton therapy by means of prompt-gamma detection is a promising but challenging approach. High count rates, energies ranging between 1 MeV and 7 MeV, and a strong background complicate the detection of such particles. In this work, the Cherenkov light generated by prompt-gammas in the pure Cherenkov emitters TlBr, TlCl and PbF was studied. Cherenkov light in these crystals can provide a very fast timing signal with the potential to achieve very high count rates and to discern between prompt-gammas and background signals. Crystals of 1×1 cm and thicknesses of 1 cm, 2 cm, 3 cm and 4 cm were simulated. Different photodetector configurations were studied for 2.3 MeV, 4.4 MeV, and 6.1 MeV prompt-gammas. TlCl achieved the greatest number of detected Cherenkov photons for all energies, detector dimensions, and photodetector efficiency modeling. For the highest prompt-gamma energy simulated, TlCl yielded approximately 250 Cherenkov detected photons, using a hypothetical high-performance photodetector. Results show the crystal blocks of 1 cm × 1 cm × 1 cm have greater prompt-gamma detection efficiency per volume and a comparable average number of detected Cherenkov photons per event.