Mixed-signal ionoacoustic analog front-end for proton range verification with 24 μm Precision at 0.8 gy bragg peak dose

This paper investigates a promising experimental technique for proton beams range verification based on Time-of-Flight (ToF) measurements of the acoustic waves emitted by the fast energy deposition occurring at the end of the particle range. In the field of oncological hadron therapy, the ionoacoustic ranging technique promises better precision than Positron Emission Tomography (PET) and opens the possibility of real-time beam monitoring, thus increasing treatment efficacy. The proposed technique has already proven to provide sub-mm accuracy at sub-clinical energies and to rely on smart and smaller (and hence more efficient) electronics instrumentation w.r.t. PET. However, state-of-the-art experiments lacks dedicated analog and digital electronics and heavily rely on offline noise rejection algorithms to achieve sub-mm precision. In this scenario, this work presents a complete analog-digital front-end dedicated to ionoacoustic experiments that improves the signal-to-noise ratio of a traditional non-dedicated systems by 6 dB and thus increments the measurement precision for a given deposited dose. The proposed system has been validated by both behavioral simulations and experimental data taken at the Maier-Leibniz Laboratories, where using the presented system a clear acoustic signal of 5 Pa amplitude and 2.3 MHz frequency has been detected at 11 dB Signal-to-Noise-Ratio with a 19.5 MeV proton beam in a water phantom target. ToF measurements allowed to determine the Bragg Peak position with 24 mu m precision and 26 mu m accuracy w.r.t. Geant4 simulations while delivering a total Bragg Peak dose of 0.8 Gy.