SU-E-T-234: LET Measurement Using Nuclear Emulsion and Monte Carlo Simulation for Proton Beam

The significant issue of particle therapy such as proton and carbon ion biological effect on tumors and normal tissue. This effect closely connected with linear-energy-transfer (LET). This work presents a Monte Carlo study using GEANT4 and the verification using Nuclear Emulsion to show LET for proton beam.

National Cancer Center (NCC) has IBA Beam Nozzle and cyclotron for proton therapy. We use proton beam bragg peak range 14cm. Also, we already developed the simulation using GEANT4 and finished validation for scattering proton beam. In our simulation, we make same condition with experimental setup.Nuclear emulsion films interleaved with tissue equivalent absorbers can be fruitfully used to reconstruct proton tracks with very high precision. This Nuclear emulsion film has been supported from Nagoya University, analyzed in Pusan University, was irradiated with a therapeutic proton beam at NCC. The Emulsion packs was located at entrance and bragg peak region of proton. This position means low and high LET region. The scanning of the emulsions has been performed at Nagoya University, where a fully automated microscopic scanning technology has been developed for the OPERA experiment on neutrino oscillations.

We could see the reconstructed track of proton scanning emulsion. From film scanning, we got the LET distribution at low and high LET region for several proton tracks. Simulation results was similar distribution within standard deviation in acceptance level. Also we got the RBE distribution using LET measurement for proton beam.

We measured LET at entrance and bragg peak region using Monte Carlo study and Nuclear Emulsion film, for NCC proton beam. This results means the good observation of LET using the nuclear emulsion. And this method can be used successfully in medical field.