Monte Carlo study of nanoparticles effectiveness on the dose enhancement when irradiated by protons

Abstract

Recently, the nanomedicine field has experienced considerable growth in research. The use of nanoparticles to enhance dose in radiation treatment was proposed and their potential effects can be indicated using Monte Carlo calculations. The main goal of this study focused on nanoparticles’ (NPs) effects on dose enhancement due to the low-energy protons because the majority of studies on NPs have been conducted for photon radiations. To investigate the effect of NPs on the Dose Enhancement Factor (DEF), a cell dimension phantom was modeled and spheres of NPs were localized inside that. Different NPs, such as Au, Pt, Ag, I, and Ta2O3, were located in the phantom, and the DEF was calculated by changing the source energy from 3 to 15 MeV. The purpose of investigating the low-energy proton beam is to clarify the effects around the Bragg peak in the presence of nanoparticles. For protons with an energy range of 3–15 MeV, it was discovered that Pt nanoparticles have a greater dose increase coefficient of about 1.8 times compared to the other nanoparticles. The findings indicated that the DEF values substantially depended on the NPs concentration, but that the DEF was not significantly affected by changes in concentration or nanoparticle size. Comparative calculations between water and soft tissue phantoms that were filled with NPs presented a difference of less than 2%. The obtained findings emphasized the importance of NPs and considered details, such as concentration, to demonstrate the potential of nanoparticles in improving treatment using protons.

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“…Another important aspect related to the nanoparticle concentration is its biological expected clearance and toxicity. Ganjeh and Salehi obtained a DEF of 1.8 when 10% concentration of PtNPs were incorporated in water and irradiated with protons of 2–15 MeV [ 53 ]. In this study, relevant DEFs were found for AuNP, even for the lower concentrations used.…”

“…Figure 2 shows the absorbance spectra of the nanoparticles, confirming its formation based on the plasmonic band of each material. According to the Mie theory, metallic nanoparticles with sizes smaller than the incident light wavelength exhibit a strong SPR absorption band in the visible to near-infrared (NIR) region, arising from the collective oscillation of free electrons on the surface of the nanoparticle [53]. The morphology and size distribution of the nanoparticles were initially examined using transmission electron microscopy (TEM), as shown in Figure 3.…”