Tumor dose enhancement by gold nanoparticles in a 6 MV photon beam: a Monte Carlo study on the size effect of nanoparticles

Abstract

It is known that by injecting materials with high atomic number into a tumor, the energy deposition can be increased due to various physical interactions between the photons and tumor tissue. Early researchers used iodine, gadolinium and gold microspheres as high atomic number media, but results were not satisfactory [7, 10, 11, 17, 18, 21–23, 26]. Subsequently, in an in vivo study, a significant increase in one-year survival in 86% of population in the group treated with radiotherapy and nanoparticles was observed compared to 20% in the group with radiotherapy alone. This study was performed on mice irradiated with 250 kVp X-rays in the presence of 1.9 nm GNPs and the results verify GNPs as a dose enhancer [9]. In vitro studies also confirmed this claim [3, 4, 15]. In these studies, a meaningful biological dose enhancement was observed after irradiation of cells and plasmid DNA. Therefore, the use of GNPs for potential clinical purpose has been a field of interest for many researchers. Dose enhancement within a tumor is influenced by the size, concentration of nanoparticles, photon beam quality, etc. Nanoparticles with sufficient small size can penetrate into the tumor tissue due to the leaky vasculature of tumors [8]. This effect takes advantage of a phenomenon which is known as enhanced permeability and retention (EPR) [16]. Nanoparticles of 1–100 nm size penetrate into a tumor from blood vessels feeding Tumor dose enhancement by gold nanoparticles in a 6 MV photon beam: a Monte Carlo study on the size effect of nanoparticles Delaram Pakravan, Mahdi Ghorbani, Mehdi Momennezhad