RESUMO
Objective To investigate a system for the detection of the acoustic signal created by clinical proton and carbon ion Bragg-peaks (BPs).Methods An acoustic detector was attached to water phantoms downstream of the beam.The water-equivalent depth of this phantom was measured by a peakfinder (PTW,Siemens,Germany) using high energy proton beams.By maintaining the same particle number,either the BP to detector distance (BTD) or beam intensity was changed to investigate their relationships with the magnitude of acoustic signal.By moving the beam spot in lateral directions,the full width at half maximums (FWHMs) of BPs was measured and compared.Results The detected acoustic signal created by beam on or beam off could represent the magnitude of signal,which was proven by a statistical analysis.The magnitude of acoustic signals created by proton BPs were inversely proportional to BTD,but proportional to intensities.The measured FWHM of 125.43 MeV proton BP was 11.7％ larger than data from the treatment planning system (TPS).Carbon ion showed similar result whereas the measured FWHM of 178.89 MeV/u carbon ion BP was 45.6％ larger than the data from TPS.The BTDs could be more than 67.7 mm while maintaining enough magnitude of acoustic signal.Conclusions This acoustic detection system can detect the acoustic waves from clinical proton and carbon ion BPs.However,further investigation is ongoing to decrease the noise.