Energy optimization in gold nanoparticle enhanced radiation therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Nanomedicine

Background:

• Gold nanoparticles (GNPs) are investigated as radiosensitizers, with kilovoltage (kV) photon beams showing high enhancement potential due to gold's interaction probability.
• Orthovoltage irradiations offer feasibility but have limited tissue penetration, necessitating optimization studies.

Purpose of the Study:

• To quantify the impact of varying photon beam energies and arrangements on GNP-based dose enhancement for breast and brain tumors.
• To evaluate treatment plan quality by comparing RBE-weighted doses to normal tissue and tumor doses.

Main Methods:

• Utilized the TOPAS-nBio Monte Carlo code to calculate radial doses and a GNP-local effect model for cell survival.
• Modeled cell survival curves with GNPs in tumor sites to determine RBE-weighted doses.
• Compared kV photon beams (50-250 kVp) with GNPs against standard 6 MV photon beams without GNPs for various tumor and GNP uptake geometries.

Main Results:

• For breast tumors, kV photon beams plus GNPs yielded up to 2.73 times higher mean RBE-weighted tumor dose than standard megavoltage beams, with equivalent normal tissue dose.
• GNP dose enhancement for brain tumors was effective for energies above 50 keV.
• Optimal conditions included small, shallow tumors, and specific GNP uptake distributions and beam arrangements were critical.

Conclusions:

• Kilovoltage photon beams combined with gold nanoparticles show significant potential for enhancing radiation therapy, particularly for specific tumor types and locations.
• Optimizing photon beam energy, arrangement, and GNP uptake is crucial for maximizing therapeutic gain in GNP-enhanced radiotherapy.