A peer-reviewed journal published by K. N. Toosi University of Technology

Proton therapy enhancement with gold, platinum, and iridium nanoparticle: A cellular-scale Geant4-DNA study

Document Type : Research Article

Authors

1 Department of Physics, Shiraz Branch, Islamic Azad University, Shiraz, Iran

2 Department of Physics, Shiraz University of Technology, Shiraz, Iran

Abstract
Combining nanoparticles (NPs) with proton therapy holds promise for improving treatment gain. Prior simulation studies often lack clinical beam realism and comprehensive radiobiological endpoints, leading to conflicting results. This study employs a Geant4-DNA Monte Carlo simulation to compare the physical and radiobiological enhancement of Au, Pt, and Ir NPs in a human cell under a clinically relevant Spread-Out Bragg Peak proton beam. A 62.8 MeV SOBP was simulated, then, phase-space files at the beam's entrance, plateau, and distal edge were obtained. They used to irradiate a fibroblast cell containing 30 mg/g NPs in the cytoplasm. Three NP sizes of 10, 50, and 100 nm were investigated at each phase-space. We calculated the dose enhancement factor (DEF) and total DNA damage enhancement. Furthermore, cell survival curves were predicted using the Two-Lesion Kinetic model. The results indicated that Ir NPs yielded the highest physical dose enhancement (up to 4.21% for 10 nm size), followed by Pt NPs (up to 4.10%). Smaller NPs tend to present a higher DEF than larger NPs. DNA damage yields increased with linear energy transfer (LET), with the distal SOBP distal edge showing the greatest enhancement. Cell survival curves indicated a detectable reduction in survival fraction for Ir > Pt > Au NPs at the distal edge, correlating with increased complex DNA damage. Under clinically realistic simulation conditions, high atomic number and high density NPs like Ir provide a modest but consistent physical and radiobiological enhancement in proton therapy, most pronounced at the high-LET Bragg peak.

Highlights

  • Various NPs were investigated for microscopic dose enhancement in proton therapy.
  • Higher DNA damages were induced at the end of the SOBP than its center.
  • Ir and Pt NPs have superiority over Au in proton dose enhancement.
  • Ir and Pt are promising radio-sensitizers for 62.8 MeV proton therapy.

Keywords

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.

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Articles in Press, Accepted Manuscript
Available Online from 11 June 2026

  • Receive Date 15 February 2026
  • Revise Date 05 May 2026
  • Accept Date 16 May 2026