Program Information
RBE Enhancement Owing to Gold NanoParticles A Geant4 Monte Carlo Study
Y Chiang*, I Cho , C Hsing , C Tung , T Chao , C Lee , Chang Gung University, Guishan Dist, Taoyuan City
Presentations
TU-C2-GePD-T-6 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Therapy ePoster Lounge
Purpose: Gold nanoparticles (GNPs) are well-studied radiosensitizers for radiotherapy. After irradiation, GNPs enhance the yield rates of secondary Auger cascade and Auger electrons. These electrons carry very low energy like few keVs and have very high lineal energy transfer (LET) and radiobiological effeteness (RBE)
Methods: In this research, we use Geant4 10.2.p02 Monte Carlo toolkit to simulate a Tissue Equilibrium Proportional Counter (TEPC) with GNPs coated on the inner wall. Simulated particles include photons with 80 keV to 18 MeV and protons with 34 MeV to 230 MeV. The cavity diameter of TEPC is 1 mm with low pressure to mimic 1 μm and 0.1 μm and gold coating thickness is from 0 to 100 nm. The tracks of charged particles through the cavity are recorded and analyzed using ROOT to get microdosimetry spectrums.
Results: The GNPs reduce the low LET particles and increase high LET particle. The frequency-mean lineal energy enhances over 30% for 662 keV photon and over 20% for 18 MeV photon. However, for high-energy proton, the deviation is not significant. Only for the protons just behind Bragg peak have a LET enhance about 8%. The dose-mean lineal energy is about 10% enhance for photons.
Conclusion: Generally speaking, GNP can be used for photon therapy due to its ability to enhance RBE. However, for proton therapy, GNP may cause problems such as increasing the RBE dose after the Bragg peak, and we hope that the dose is shown to be as low as possible.
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