Study on radiosensitization performance of dual-energy X-ray intraoperative radiotherapy based on Monte Carlo simulations

Radiosensitization with nanoparticles (NPs) remains a feasible way to enhance the efficiency of intraoperative radiotherapy (IORT). For the first time, this study proposed the energy-selective method with application of NPs for IORT, of which a magnetic modulated two-target X-ray tube was employed. Monte Carlo (MC) simulation of MCNP5 was used to calculate the dose enhancement effect (DEF). The DEF of Fe, Au with weight fraction of 0.5% was evaluated. It confirmed gold NPs were the desired choice with dose enhancement within 18 mm from the surface of the X-ray tube applicator. Additionally, the dose profile was assessed at the plane with 3 mm depth. Which showed electrons were successfully deflected. Furthermore, the influence by different gold mixtures was evaluated, which were 0.5%, 1.0%, 1.5%, 2.0% of Au. with concentrations increased to 2.0%, the maximum absorbed dose was improved to 627 MeV/g with DEF of 2.85 at the applicator surface of Zr-target spectrum. Thus, this paper showed the possibility to improve the dose distribution to tumor bed within 18 mm by using gold NPs and modulating the emission X-ray spectrum, it will also decrease the dose to the normal tissues.