Relative efficiency of EBT3 radiochromic films to proton and carbon ion beams.

Radiochromic films (EBT3) are adopted for dosimetric verification and for QA for radiotherapy; however, their use in hadrontherapy is limited to QA procedures. Indeed, a quenching effect occurs consisting of an under-response of the EBT3 film to ion beams with respect to MV-photon beams, at equal dose levels, due to the ion track structure. To investigate the response of EBT3 films irradiated with protons and carbon ions with respect to photons and electrons. The response of EBT3 films to protons and ¹²C was investigated and compared in terms of Relative Efficiency (RE) with photons and electrons response (dose range 0.4–20 Gy). For protons (63–230 MeV) the RE is constant at 0.984 ± 0.004. For ¹²C (115–400 MeV/u) the RE is less than unity. The line fit slope for each energy is consistent with zero and the intercepts are 0.695 ± 0.007 (115 MeV/u), 0.773 ± 0.007 (400 MeV/u) and 0.864 ± 0.007 (250 MeV/u). For protons (63–230 MeV) the response of EBT3 is not different from that of photons within experimental uncertainties (2%). For ¹²C (115–400 MeV/u) EBT3 films show an under-response with respect to photon beams. For ¹²C ions the response of EBT3 film is dependent on the energy and the under-response is of about 31% for 115 MeV/u, 14% for 250 MeV/u and 23% for 400 MeV/u. [ABSTRACT FROM AUTHOR]