Radio-enhancement by gold nanoparticles and their impact on water radiolysis for x-ray, proton and carbon-ion beams.

Radio-enhancement by gold nanoparticles and their impact on water radiolysis for x-ray, proton and carbon-ion beams.
Phys Med Biol. 2019 Jul 11;:
Authors: Rudek B, McNamara AL, Ramos-Mendez J, Byrne H, Kuncic Z, Schuemann J
Abstract
Gold nanoparticle (GNP) radio-enhancement is a promising technique to increase the dose deposition in a tumor while sparing neighboring healthy tissue. Previous experimental studies showed effects on cell survival and tumor control for keV x-rays but surprisingly also for MV-photons, proton and carbon-ion beams. In a systematic study, we use the Monte Carlo simulation tool TOPAS-nBio to model the GNP radio-enhancement within a cell as a function of GNP concentration, size and clustering for a wide range of energies for photons, protons and, for the first time, carbon-ions. Moreover, we include water radiolysis, which has been recognized as a major pathway of GNP mediated radio-enhancement. 
 At a GNP concentration of 0.5% and a GNP diameter of 10nm, the dose enhancement ratio was highest for 50keV x-rays (1.36) and decreased in the orthovoltage (1.04 at 250keV) and megavoltage range (1.01 at 1MeV). The dose enhancement linearly increased with GNP concentration and decreased with GNP size and degree of clustering for all radiation modalities. While the highest physical dose enhancement at 5% concentrations was only 1.003 for 10MeV protons and 1.004 for 100MeV carbon-ions, we find the number of ...

Source: Physics in Medicine and Biology - July 10, 2019 Category: Physics Authors: Rudek B, McNamara AL, Ramos-Mendez J, Byrne H, Kuncic Z, Schuemann J Tags: Phys Med Biol Source Type: research