Estimation of Dose Enhancement for Inhomogeneous Distribution of Nanoparticles: A Monte Carlo Study

Fouad Abolaban,Eslam Taha,Abdulsalam Alhawsawi,Fathi Djouider,Essam Banoqitah,Andrew Nisbet

doi:10.3390/app11114900

Fouad Abolaban, Eslam Taha + Show 4 more

Open Access

https://doi.org/10.3390/app11114900

Copy DOI

Abstract

High atomic number nanoparticles are of increasing interest in radiotherapy due to their significant positive impact on the local dose applied to the treatment site. In this work, three types of metal nanoparticles were utilized to investigate their dose enhancement based on the GATE Monte Carlo simulation tool. Gold, gadolinium, and silver were implanted at three different concentrations to a 1 cm radius sphere to mimic a cancerous tumor inside a 10 × 10 × 30 cm3 water phantom. The innermost layer of the tumor represents a necrotic region, where the metal nanoparticles uptake is assumed to be zero, arising from hypoxic conditions. The nanoparticles were defined using the mixture technique, where nanoparticles are added to the chemical composition of the tumor. A directional 2 × 2 cm2 monoenergetic photon beam was used with several energies ranging from 50 keV to 4000 keV. The dose enhancement factor (DEF) was measured for all three metal nanoparticles under all beam energies. The maximum DEF was ~7 for silver nanoparticles with the 50 keV beam energy at the highest nanoparticle concentration of 30 mg/g of water. Gold followed the same trend as it registered the highest DEF at the 50 keV beam energy with the highest concentration of nanoparticles at 30 mg/g, while gadolinium registered the highest at 100 keV.

Highlights

Growing solid tumor cancer cells are commonly subject to hypoxia and nutrient deficiency due to limited blood supply near the tumor center [1]
It was initially intended for emission tomography applications, the toolkit was extended to cover a broader range of dosimetry and radiotherapy applications [38,39,40,41]
The GATE toolkit was used to determine the dose enhancement factor (DEF) resulting from inhomogeneous nanoparticle uptake for various energies

Summary

Introduction

Growing solid tumor cancer cells are commonly subject to hypoxia and nutrient deficiency due to limited blood supply near the tumor center [1]. This may result in necrosis or passive cell death within the tumor core [2]. Radiotherapy is considered a critical component in any national cancer-control plan. More than half of cancer patients receive this modality during their treatment, contributing to an overall cure rate of over 40% [3]. Accurate targeting of the tumor is especially important for tumors that are contiguous to critical body organs [6]. The main aim of RT is to maximize the damage to the cancer tumor and minimize the effect of radiation injury to the surrounding healthy tissues [7]

Methods

Results

Discussion

Conclusion