Beam Energy Considerations for Gold Nano-Particle Enhanced Radiation Treatment

TL;DR

This study explores how gold nanoparticles can enhance radiation therapy effectiveness by increasing dose deposition through photo-electric interactions and electron generation, with potential for clinical application.

Contribution

It introduces a Monte Carlo simulation-based analysis of dose enhancement factors considering nanoparticle concentration, photon energy spectra, and target positioning, highlighting practical clinical implications.

Findings

Dose enhancement increases linearly with nanoparticle concentration.

Optimal energy spectra depend on target position and photon energy.

Regular clinical X-ray spectra provide comparable enhancement to optimized mono-energetic sources.

Abstract

Purpose: A novel approach using nano technology enhanced radiation modalities is investigated. The proposed methodology uses antibodies labeled with organically inert metals with a high atomic number. Irradiation using photons with energies in the kilo--electron volt (keV) range show an increase in dose due to a combination of an increase in photo-electric interactions and a pronounced generation of Auger and/or Coster-Kronig (A-CK) electrons. Methods: The dependency of the dose deposition on various factors is investigated using Monte Carlo simulation models. The factors investigated include: agent concentration, spectral dependency looking at mono--energetic sources as well as classical bremsstrahlung sources. The optimization of the energy spectrum is performed in terms of physical dose enhancement as well as the dose deposited by Auger and/or Coster-Kronig electrons and their biological effectiveness. Results: A quasi-linear dependency on concentration and an exponential decrease within the target medium is observed. The maximal dose enhancement is dependent on the position of the target in the beam. Apart from irradiation with low photon energies (10 - 20 keV) there is no added benefit from the increase in generation of Auger electrons. Interestingly, a regular 110kVp bremsstrahlung spectrum shows a comparable enhancement in comparison with the optimized mono--energetic sources. Conclusions: In conclusion we find that the use of nano-particle enhanced shows promise to be implemented quite easily in regular clinic on a physical level due to the advantageous properties in classical beams.