Calibration of Gafchromic EBT3 for Dose Measurements in Low-Energy Proton Beam

The use of radiochromic film (RCF) dosimetry is widely consolidated for applications in photon, electron and proton beams. It offers several advantages, in particular, two-dimensional measurements of dose distributions with high spatial resolution, no post irradiation processing required and no daylight sensitivity. In addition, it shows small LET and energy dependence. GAFCHROMIC® EBT3 films, recently commercialized by International Specialty Products (ISP, Wayne, NJ) [1], are being widely used because of their good characteristics and improvements with respect to the previous model EBT2: their symmetric layer configuration allows the user to eliminate side orientation-dependence, and the presence of microscopic silica particles embedded into the polyester substrate prevents the formation of Newton’s rings in images obtained using a flatbed scanner. The purpose of the study was to implement EBT3 dosimetry in the TOP (Oncological Therapy with Protons)IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) [2] proton accelerator under realization at ENEA-Frascati, specifically, in the proton low-energy radiobiology line devoted to cell irradiation having a maximum energy of 7 MeV. In the present work we investigate the response vs. absorbed dose of EBT3 in proton beam energy of 5 MeV in the (0.5 – 30) Gy dose range. The irradiation with proton beam was performed at the Radiobiology irradiation facility of the 7 MV Van de Graaff CN accelerator at the INFN-Laboratori Nazionali di Legnaro-Padova (INFN-LNL), Italy [3]