Simulation of Cherenkov Light by Prompt-Gammas in Pure Cherenkov Emitters for Proton Range Verification

Live assessment of the proton range in proton radiotherapy is an outstanding problem. Proton range verification (PRV) by means of prompt-gammas is a promising approach provided their prompt time properties and characteristic energies when compared to other radiation byproducts of the proton beam. In this work, we study the Cherenkov light created by such prompt-gammas in pure Cherenkov emitters with the aim of using it as an effective discriminator and achieve high count rates. Crystals of TlBr, TlCl and PbF2 with dimensions of 1×1×1 cm3 and 1×1×2 cm3 coupled to a 1×1 mm2 photodetector on one of their faces were simulated. The interaction processes and energy deposited in the crystal showed a strong relation with the generation and detection of Cherenkov photons, thus shaping the yield distributions and, consequently, impacting the average yield results. Pair production was the process that contributed the most to high yield events and was more present with increasing prompt-gamma energies, while Compton scattering dominated at lower energies. Cherenkov light detection yield was studied for different photodetector scenarios. Among materials, TlCl achieved the highest Cherenkov yield results across all energies, detector dimensions, and photodetector efficiency modeling. Crystals with 2 cm thickness showed a greater number of total detected events than 1 cm-thick ones. However, the average Cherenkov yield per event was the same for each material regardless of crystal length. The next step of this study is to model a prototype consisting of an array of such detectors.