title: Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital-based clinical cyclotron.
abstract: OBJECTIVE
  To measure the acoustic signal generated by a pulsed proton spill from a hospital-based clinical cyclotron.
  
  
  METHODS
  An electronic function generator modulated the IBA C230 isochronous cyclotron to create a pulsed proton beam. The acoustic emissions generated by the proton beam were measured in water using a hydrophone. The acoustic measurements were repeated with increasing proton current and increasing distance between detector and beam.
  
  
  RESULTS
  The cyclotron generated proton spills with rise times of 18 μs and a maximum measured instantaneous proton current of 790 nA. Acoustic emissions generated by the proton energy deposition were measured to be on the order of mPa. The origin of the acoustic wave was identified as the proton beam based on the correlation between acoustic emission arrival time and distance between the hydrophone and proton beam. The acoustic frequency spectrum peaked at 10 kHz, and the acoustic pressure amplitude increased monotonically with increasing proton current.
  
  
  CONCLUSIONS
  The authors report the first observation of acoustic emissions generated by a proton beam from a hospital-based clinical cyclotron. When modulated by an electronic function generator, the cyclotron is capable of creating proton spills with fast rise times (18 μs) and high instantaneous currents (790 nA). Measurements of the proton-generated acoustic emissions in a clinical setting may provide a method for in vivo proton range verification and patient monitoring.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Jones
authors.affiliation: Ion Beam Applications SA, Louvain-la-Neuve 1348, Belgium.
authors.forename: François
authors.initials: F
authors.lastname: Vander Stappen
authors.affiliation: School of Biomedical Engineering, Drexel University, Philadelphia, Pennsylvania 19104.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Bawiec
authors.affiliation: Ion Beam Applications SA, Louvain-la-Neuve 1348, Belgium.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Janssens
authors.affiliation: School of Biomedical Engineering, Drexel University, Philadelphia, Pennsylvania 19104.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Lewin
authors.affiliation: Ion Beam Applications SA, Louvain-la-Neuve 1348, Belgium.
authors.forename: Damien
authors.initials: D
authors.lastname: Prieels
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Solberg
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
authors.forename: Chandra M
authors.initials: CM
authors.lastname: Sehgal
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
authors.forename: Stephen
authors.initials: S
authors.lastname: Avery
mesh_terms: D017357:Cyclotrons; D006761:Hospitals; D011312:Pressure; D061766:Proton Therapy / Q000295:instrumentation*; D013016:Sound; D014867:Water
chemical_list: D014867:Water