Improvement of performance for flexible film dosimeter by incorporating additive agents

Objective.To evaluate the reduction in energy dependence and aging effect of the lithium salt of pentacosa-10,-12-diynoic acid (LiPCDA) films with additives including aluminum oxide (Al₂O₃), propyl gallate (PG), and disodium ethylenediaminetetracetate (EDTA).Approach. LiPCDA films exhibited energy dependence on kilovoltage (kV) and megavoltage (MV) photon energies and experienced deterioration over time. Evaluations were conducted with added Al₂O₃and antioxidants to mitigate these issues, and films were produced with and without Al₂O₃to assess energy dependence. The films were irradiated at doses of 0, 3, 6, and 12 cGy at photon energies of 75 kV, 105 kV, 6 MV, 10 MV, and 15 MV. For the energy range of 75 kV to 15 MV, the mean and standard deviation (std) were calculated and compared for the values normalized to the net optical density (netOD) at 6 MV, corresponding to identical dose levels. To evaluate the aging effect, PG and disodium EDTA were incorporated into the films: sample C with 1% PG, sample D with 2% PG, sample E with 0.62% disodium EDTA added to sample D, and sample F with 1.23% disodium EDTA added to sample D.Main results. Films containing Al₂O₃demonstrated a maximum 15.8% increase in mean normalized values and a 15.1% reduction in std, reflecting a greater netOD reduction at kV than MV energies, which indicates less energy dependence in these films. When the OD of sample 1-4 depending on the addition of PG and disodium EDTA, was observed for 20 weeks, the transmission mode decreased by 8.7%, 8.3%, 29.3%, and 27.3%, respectively, while the reflection mode was 5.4%, 3.0%, 37.0%, and 34.5%, respectively.Significance. Al₂O₃effectively reduced the voltage and MV energy dependence. PG was more effective than disodium EDTA in preventing the deterioration of film performance owing to the aging effect.