Estimating the stopping power distribution during proton therapy: A proof of concept

Objective: We introduce a new treatment verification technique to estimate the primary particle’s stopping power from prompt gamma timing measurements in proton therapy. Approach: The starting point is Spatio-temporal Emission Recostruction technique, which provides time-depth distribution of emitted photons with multiple Prompt-Gamma Timing detector setup based on Lanthanum Bromide crystals. A dedicated formalism an analytical approximation developed obtain desired information. Its performance evaluated proof concept configuration via Monte Carlo simulations monochromatic beams impinging homogeneous PMMA phantom. Main Results: Results indicate estimations as good 3.8% respect NIST values, and range within 0.3 cm (standard deviation), when considering 250 ps FWHM resolution. Significance: current study shows, for first time, feasibility evaluating that can be performed in-vivo, opening up possibilities field therapy optimization.