Objective(s): Integrating magnetic resonance imaging (MRI) with proton therapy holds significant promise for enhancing treatment efficacy. Magnetic nanoparticles (MNPs), such as gadolinium and superparamagnetic iron oxide nanoparticles (SPIONs), are well-known for improving tissue contrast in MRI. In this study, we investigate the potential of core–shell nanoparticles (Au@MNPs) as agents that can enhance the delivery of therapeutic doses to targeted tissues. Specifically, we examine how variations in core diameter and shell thickness, using either gadolinium oxide (Gd₂O₃) or SPION shells, influence dose enhancement.
Materials and Methods: A simulated proton beam with a weighted energy spectrum—representing both primary and secondary protons within the Spread-Out Bragg Peak (SOBP) region—was used to irradiate the nanoparticles. The energy deposited within the nanoparticles, as well as the phase space of surrounding secondary particles, was evaluated. Key parameters, including energy efficiency, total energy release, and the number of secondary electrons, were analyzed to compare the performance of various nanoparticle designs.
Results: Our findings indicate that incorporating a gold core is advantageous for thin magnetic layers (<15 nm), as it enhances the dose around the nanoparticle while maintaining a size compatible with MRI applications (<20 nm). In contrast, for thicker magnetic layers (greater than 20 nm), a larger gold core diameter is required to achieve effective dose enhancement.
Conclusion: These results suggest that embedding a gold core with a diameter of less than 15 nm within MRI-compatible nanoparticles is a promising strategy for enhancing dose delivery in proton therapy. Further studies are warranted to investigate the impact of core–shell nanoparticles on magnetic properties, which are critical for their theranostic potential.