Enhanced dose measurement of zinc oxide nanoparticles by radiochromic polymer dosimeter and Monte Carlo simulation.

Abstract

The aim of this study is to evaluate the effects of Zinc Oxide nanoparticles on dose enhancement factor using PRESAGE dosimeter and Monte Carlo simulation. High Z materials absorb X-ray remarkably. Among Nano-science, Zinc Oxide nanoparticles are interesting semiconductors, producing reactive oxygen species when irradiated by photons. Therefore, it seems that dose enhancement originating by incorporating ZnO NPs in irradiated volume would increase the therapeutic ratio. Initially, the PRESAGE dosimeter was fabricated and calibrated. Then Zinc Oxide nanoparticles with an average particle size of about 40 nm were synthesized. At next step, various concentrations of the nanoparticles were incorporated into the PRESAGE composition and irradiated in radiation fields. Then, the mentioned processes were simulated. Practical measurements revealed that by incorporating 500, 1000 and 3000 μg ml-1 ZnO NPs into PRESAGE the dose enhancement factor of 1.36, 1.39, 1.44 for 1 × 1 cm 2 field size, 1.39, 1.41, 1.46 for 2 × 2 cm 2 and 1.40, 1.45 and 1.50 for 3 × 3 cm 2 could be found, respectively. Simulation results showed that in the mentioned condition, the dose enhancement factor of 1.05, 1.08, 1.10 for 1 × 1 cm 2 field size, 1.06, 1.09, 1.10 for 2 × 2 cm 2 and 1.08, 1.11 and 1.13 for 3 × 3 cm 2 could be derived, respectively. The results of this study showed that dose enhancement increases by increasing concentration of Zinc Oxide nanoparticles. Many reasons such as photoelectric, pair production effects and even Compton scattering can cause dose enhancement for megavoltage beams.