Dosimetry for low energy protons with ionization chambers and EBT3 films in the BRAGG peak region

Abstract

Introduction Protons beams are largely used for tumor therapy thanks to their property of delivering dose in a small localized area (Bragg peak). The 3 MV Tandem accelerator at CNA allows to perform measurements with low energy protons. By degrading passively the beam energy, we can study the dosimetry at the end of the range in tissue of therapeutic proton beams. Purpose Study of dosimetry in the Bragg peak region, in order to establish a dosimetry protocol in such region. Materials and methods A special device was used to degrade passively the energy of the beam. It mainly consists of a precise positioning system and a holder designed to house a ionization chamber (IC) and radiochromic films, which allowed to perform dosimetry studies at different distances in air. Results We present an experimental study of the Bragg peak in air using two ICs, the dosimetry with radiochromic films in the Bragg peak region and the comparison of data with Geant4 Monte Carlo simulations. Moreover, we expect to give a characterization of the radiochromic film dosimetry for the Bragg peak region where effects of saturation are occurring comparing Geant4 simulations with experimental data. Conclusion Few studies have been conducted until now to quantify the dose deposition in the Bragg peak, and by means of such measurements we are trying to establish a dosimetry protocol in such region, using Monte Carlo simulations and measurements with ICs and radiochromic films. Disclosure The authors have no conflicts of interest.