Radiation Physics and Engineering
A peer-reviewed journal published by K. N. Toosi University of Technology

‎M‎onte Carlo-based numerical assessment of metal and metal oxide nan‎‎oparticle parameters on cellular dose enhancement in proton therap‏y‎

Articles in Press

Document Type : Research Article

Authors

Parisa Bidokhti 1
Keyhandokht Karimi-Shahri 1
Mahdi Ghorbani 2

1 Department of Physics, Faculty of Science, University of Birjand, Birjand, Iran

2 Biomedical Engineering and Medical Physics Department, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

https://doi.org/10.22034/rpe.2026.568320.1330
Abstract
Proton therapy is an effective cancer treatment due to its precise dose distribution and the presence of the Bragg peak. The incorporation of high-Z nanoparticles has emerged as a promising strategy to further enhance local dose deposition in tumor cells. This study aims to evaluate the dose enhancement effect of metal and metal oxide nanoparticles in cellular environments under proton irradiation. Monte Carlo simulations were performed using the GEANT4 toolkit with the GEANT4-DNA extension to model proton interactions at the microscopic scale. The influence of nanoparticle material (gold, iron oxide, and hafnium oxide), concentration (10-90 mg.ml-1), and size (5-25 nm) on the dose enhancement ratio in the nucleus and cytoplasm of a single cell was investigated. Results show that the dose enhancement ratio (DER) increased linearly with nanoparticle concentration, while increasing nanoparticle size caused a nonlinear decrease in the DER. Among the studied nanoparticles, gold nanoparticles showed the highest dose enhancement due to their higher atomic number and density. Nanoparticle type, size, and concentration are critical factors for maximizing dose enhancement in proton therapy, with gold nanoparticles offering the greatest potential to increase therapeutic efficacy.

Highlights

  • Monte Carlo simulations assessed nanoparticle-induced dose enhancement in proton therapy at the cellular level.
  • Dose enhancement increased linearly with nanoparticle concentration and decreased nonlinearly with size.
  • Gold nanoparticles produced the highest dose enhancement compared to hafnium and iron oxides.
  • The cytoplasm exhibited higher dose enhancement compared to the nucleus.
  • Dose enhancement in proton therapy depends on nanoparticle material, size, and concentration.

Keywords

Proton therapy
Nanoparticle
Dose Enhancement Ratio
GEANT4 toolkit
Cell nucleus and cytoplasm
Subjects

Copyright
RPE is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Conflict of Interest
The authors declare no potential conflict of interest regarding the publication of this work‎.

Funding
‎The authors declare that no funds‎, ‎grants‎, ‎or other financial support were received during the preparation of this manuscript‎.

Radiation Physics and Engineering

Articles in Press, Accepted Manuscript
Available Online from 12 June 2026

  • Receive Date 24 December 2025
  • Revise Date 18 May 2026
  • Accept Date 23 May 2026

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