In cooperation with the Iranian Nuclear Society

Investigating the Effect of Magnetic Field on Nanoparticle Dose Enhancement in Protontherapy: Comparison of Single-stage and Phase-space Simulation Approaches

Document Type : Research Paper

Authors

1 Sharif University of Technology

2 Institute for Research in Fundamental Sciences, IPM

Abstract
Recently, special attention has been paid to the use of nanoparticles (NPs) in radiation therapy to enhance the therapeutic gain. Combining proton therapy with Magnetic Resonance Imaging has been developing rapidly. One of the associated challenges is the possible impact of a magnetic field on the dose distribution around NPs. In the present study, the dose enhancement factor of a 25 nm radius gold, gadolinium, and superparamagnetic iron oxide NP irradiated by protons of 50, 150, and 250 MeV has been examined with and without the presence of a static magnetic field with different strengths. In addition, two simulation approaches (single-stage and phase-space approaches) using the Geant4 toolkit are considered and the results from two electromagnetic physical lists, Livermore and Penelope, are compared. The results show that using heavier NPs (i.e., high density and effective atomic number) increases the dose more than the lighter ones. The difference between the two investigated physics lists is significant in the low-energy region and reaches up to 20% in dose enhancement factor calculations. Moreover, a magnetic field with a strength of up to 7 T did not reveal a significant effect on the dose distribution around NPs and the number of secondary particles. The results of this study have paved the way for experimental studies of the feasibility of combining proton therapy with the simultaneous presence of NPs and magnetic field, which can be helpful before the start of the clinical phase.

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Articles in Press, Accepted Manuscript
Available Online from 25 May 2025

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