A simulation study on the effect of penetration of gold nanoparticles in the cytoplasm of healthy eye organs on dose enhancement of brachytherapy

Abstract

Purpose

Special properties and recent advances in the synthesis and biomolecular functionalization of gold nanoparticles (GNPs) have led to the evolution of their use in biomedical applications such as photon radiotherapy. Simulation-based studies on the effect of various parameters that govern the dose enhancement due to utilizing GNPs have facilitated the progress of knowledge in this field. Due to their flexibility and easier accessibility compared with experimental works, simulations have the potential to be considered for pre-clinical tests and, therefore, should be close to the realistic conditions as much as possible.

Materials and methods

To this aim, the present work investigates the effect of the presence of GNPs that are accumulated in the cytoplasm of the constituent cells in healthy tissues of a human eye phantom, inspired by the published experimental results which report that non-target tissues also receive the drugs containing GNPs. The GNPs’ concentrations are assumed to decrease by moving from the tumor toward the depth of the phantom through a suggested pattern. The MCNPX Monte Carlo code is used for the simulations.

Results

The results show that for four concentrations tested, the dose enhancement factor in the shallower layer reaches 6, and decreases to 1.2 in the last layer. The dose enhancements are also examined for critical structures of the iris, cornea, sclera, and lens, showing maximum deviations of about 3 to 200% compared with the absence of GNPs in the healthy tissue. Considering the reported doses to the lens by clinical institutions, the effect of penetration of GNPs to deep layers on treatment time is also investigated.

Conclusions

The results show that the penetration of GNPs from the tumor toward healthy tissues strongly controls the dose enhancement over the various eye structures and emphasizes the importance of modeling the GNPs’ distribution in the medium on the overall dose enhancement. Considering the current challenges in the clinical use of GNPs, more effort needs to be made to reach an effective endpoint in treatment.

Keywords:

• Brachytherapy
• COMS eye plaque
• gold nanoparticles (GNPs)
• cell model
• dose enhancement factor (DEF)
• Monte Carlo simulation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Notes on contributors

Fatemeh S. Rasouli

Fatemeh S. Rasouli, PhD, is an Associate Professor of Physics at K.N. Toosi University of Technology. She works on simulations and particle tracking using Monte Carlo-based toolkits for radiation application purposes, more especially in medical uses.

S. Farhad Masoudi

S. Farhad Masoudi, PhD, is a Professor of Physics at K.N. Toosi University of Technology. He is interested in computational physics and Monte Carlo simulations and works on ways to use these methods in applied physics, especially in radiation applications. He also has professional skills in employing artificial intelligence in physics.