Comparison of Proton Energy Deposition from Monte Carlo Simulations and Measurement Results

ProNova's mission is to deliver a lower-cost, smaller, lighter and more energy efficient solution for Proton Therapy without sacrificing performance and improving upon existing capabilities. A high current, isochronous cyclotron (Sumitomo P235) is used as the mono-energetic 230 MeV proton beam source for the ProNova SC360 Proton Therapy System installation at the Knoxville Provision Center for Proton Therapy (PCPT). The energy of the proton beam ranges from 70 MeV to 230 MeV in the treatment room by adjusting the thickness of a Beryllium degrader installed at the Energy Section Beamline (ESB) for each treatment room. In order to better characterize the proton energy loss in the treatment volume, the proton energy deposition in a water phantom located at the treatment position is analyzed in this study, including Monte Carlo simulation and experimental measurements for different energies. It is concluded that Monte Carlo simulations give a good prediction of proton energy deposition. The results also confirmed that at increasing beam energy, protons will have broader FWHM and decreased peak-to-entrance dose ratio. The ProNova SC360 design results in an energy spread that does not change linearly with the energy due to the unique degrader and ESB design. Monte Carlo simulation results match proton beam measurement well. The Monte Carlo simulation results, validated by measurement, will be used as proton beam data for Treatment Planning System commissioning. (authors)