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Monte Carlo Calculation of Zinc Oxide Nanoparticles Enhanced Dose & Comparison with Radiochromic Dose Measurements

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H Nedaie

N Banaee1 , H Nedaie2*, D Khezerloo3 , (1) Department of Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran. (2) Odette Cancer Centre, University of Toronto, Toronto, Canada. (3) Tabriz university of medicine, Faculty of paramedical science, department of radiology, Tabriz, Iran.


SU-I-GPD-T-347 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: The aim of this study is to evaluate the effects of Zinc Oxide nanoparticles (ZnO NPs) on dose enhancement factor by Monte Carlo MCNP6 simulation and radiochromic gel.

Methods: Initially, the related geometry and nanoparticles were simulated and then the accuracy of simulated geometry was validated by ion chamber measurements. At next step, radiochromic dosimeter was fabricated and calibrated. Then ZnO NPs were synthesized, incorporated into the composition of the dosimeter and irradiated in small radiation fields by 6 MV photon beams. By comparing the results in terms of the presence and lack of nanoparticles, dose enhancement factor was acquired.

Results: Monte Carlo calculation revealed that by incorporating 500, 1000 and 3000 μg ml-1 ZnO NPs into the structure of radiochromic dosimeter, the dose enhancement factors of about 1.05, 1.08, 1.10 for 1×1 cm2 field size, 1.06, 1.09, 1.10 for 2×2 cm2 and 1.08, 1.11 and 1.13 for 3×3 cm2 could be found, respectively. Experimental dosimetry showed that in the mentioned condition, the dose enhancement factor of about 1.36, 1.39, 1.44 for 1×1 cm2 field size, 1.39, 1.41, 1.46 for 2×2 cm2 and 1.40, 1.45 and 1.50 for 3×3 cm2 could be derived, respectively.

Conclusion: The results of this study showed that ZnO NPs could be used as dose enhancing substances in megavoltage irradiation conditions. Experimental measurements showed that dose enhancement increases by increasing concentration of NPs and therefore, the therapeutic ratio would rise. Many other reasons such as photoelectric, pair production effects and even Compton scattering can cause DEF. Although MCNP6 simulation code can be considered as a proper method for simulating NPs distribution, the weak potential of MCNP6 in tracing the Auger electrons which have a significant role on dose enhancement factor cause to underestimate the energy deposition of such low energy particles.

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