22 dB Signal-to-Noise Ratio Real-Time Proton Sound Detector for Experimental Beam Range Verification
Elia A. Vallicelli, A. Basçhirotto, Sebastian Lehrack, W. Assmann, Katia Parodi, S. Viola, G. Riccobene, Marcello De Matteis
Abstract
This paper presents the design and experimental characterization of a Proton Sound Detector (ProSD), a device that physically captures and senses the weak acoustic signal emitted by the fast energy deposition at the end of the same proton beam range. The measured acoustic signal Time-of-Flight provides a very accurate (13 μm accuracy) measure of the proton beam penetration depth in water, improving the proton range verification accuracy w.r.t. previous works in pre-clinical scenarios. This suggests interesting possibilities for high-accuracy and real-time beam monitoring and calibration in hadron-therapy for cancer treatment. The detector has been fully characterized and tested with a physical 20 MeV proton beam in a water energy absorber. The ProSD and the water tank have been mounted in front of the exit layer of a 20 MeV 120 ns pulse time-width proton beam. A clear sinusoidal-like acoustic signal of 5 Pa and 2.3 MHz frequency has been detected at 12 dB SNR with 0.8 Gy single shot dose. After averaging 10 beam shots the achieved Signal-to-Noise-Ratio is 22 dB allowing a ±7.5 μm precision vs. previously reported ±45μm ionoacoustic precision.