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Due to distinct photoelectric absorption properties and physiochemical features, high-atomicelement nanomaterials are frequently used as radiosensitizer for radiotherapy, such as gold nanoparticles. which in-turn can increase radiation dose to tumours while minimizing exposure to normal tissues. The aim of this study is to investigate the dose enhancement due to the presence of nanogold particles mixed with breast tissue using a real radiotherapy plan with two photon energies, with and without flattening filter. A fully validated linac head was used to model a complete field-in-field (FIF) radiotherapy breast plan using 4 and 6 MV with a flattening filter (FF) and flattening filter-free (FFF) using BEAMnrc/EGSnrc MC code. The dose distributions were simulated in a female ICRP voxel computational phantom. The dose enhancement ratio (DER) and flattening filter-free enhancement ratio (FFFER) were calculated for a range of nanogold concentrations. The results showed that the DER increased with increasing nanogold concentration. The maximum DER was achieved when FFF was used and the increase was higher for 4 MV than 6 MV. The FFFER was higher for the 4 MV beam than 6 MV when 40 mg/ml nanogold was used. The combination of higher nanogold concentrations, lower photon energies, and FFF resulted in a higher dose enhancement. The implementation of nanogold particles in breast tissue enhanced the dose deposition, especially with FFF, as presented in this study. The results would improve nanogold-enhanced breast radiotherapy and dose delivery with an increase in patient throughput. [ABSTRACT FROM AUTHOR]

Using a male ICRP voxel computational phantom, Monte Carlo simulations were performed to estimate the dose enhancement ratio (DER) in prostate radiation for 6 and 10 MV photon energy. A fully validated linear accelerator head was used, initially with a single beam to calculate the DER for different concentrations of nanogold mixed with prostate tissue. Each energy was tested with (FF) and without (FFF) a flattening filter. The DER was then calculated for a verified 10 MV treatment plan to mimic the real treatment scenario. The results showed that the DER increased with concentration, especially for FFF mode. In addition, the flattening filter-free enhancement ratio (FFFER) was investigated, from which it was found that a 6 MV FFF with a 40 mg/ml concentration enhanced the dose by a factor of 1.03 compared to 6 MV FF. For the entire plan, the difference between FFF and FF for both energies was approximately 2%. [ABSTRACT FROM AUTHOR]