Front-end design optimization for ionoacoustic 200 mev protons beam monitoring with sub-millimeter precision for hadron therapy applications

This paper presents the design of a multichannel acoustic detector optimized for sensing proton induced thermo-acoustic signals (ionoacoustic signals) in clinical scenarios experiments. Ionoacoustics is a promising technique for real-time monitoring of proton beams with interesting possible applications in oncological hadron therapy. However, clinical scenarios are characterized by very low signal amplitudes (few tens millipascals). State-of-the-art experiments use general purpose acoustic sensors and heavily rely on averaging (up to thousands beam shots) to detect a clear signal, at the cost of a significant extra-dose above clinical limits. To overcome this limit, this paper presents the design of a dedicated acoustic sensor that exploits spatial correlation (multichannel sensor) to increase the SNR with no extra-dose and localize the maximum energy deposition of a 200 MeV proton beam in clinical scenarios (35 mGy/shot dose, 25 mPa signal amplitude). The results are validated by a complete cross-domain simulation of the physical (proton beam), acoustic (wave propagation) and electrical (sensor and electronics frequency response and noise) environments. The presented detector achieves a clear 20.5 dB single-shot SNR (35 mGy total dose) and can localize the maximum energy deposition with 0.5 mm precision (<1% w.r.t. the particle range) with ~1/100 dose reduction compared to state-of-the-art.