(Monday, 7/15/2019) 9:30 AM - 10:00 AM
Room: Exhibit Hall | Forum 1
Purpose: To investigate the dependence of gold nanoparticle (GNP) dose enhancement on intracellular localization using a single cell model.
Methods: A simple Geant4 model was built using a spherical cell geometry, spherical GNPs, and a parallel beam photon source. The cell is modeled as a water sphere 20 μm in diameter with a concentric spherical cell nucleus of 10 μm in diameter. The size and number of GNPs modeled was a realistic intracellular concentration obtained from published literature and consisted of 12,000 individual GNPs 90nm in diameter. The intracellular localization of the GNPs was modeled using three distributions: all GNPs within 1 μm from the nuclear wall, uniformly distributed throughout the cytoplasm, or within 1 μm from the cellular wall. Geant4-DNA physics was used to model the low energy interactions within the cell, and Livermore physics to model the interactions in the gold spherical shell. 300 billion events were modeled for 100 keV and 6 MV photons using a parallel plane beam of radius 25 μm.
Results: The 100 keV photon simulation showed a drastic increase of more than 125% for nuclear dose, when GNPs are in close proximity to the nucleus. The increment remains 14.8% for nuclear dose, even the GNPs are furthest from the nucleus. For 6 MV a much smaller 7.45% increment in nuclear dose is observed, when GNPs are in close proximity to the nucleus. The results for cellular dose show a similar trend to the nuclear dose. There is a clear and significant correlation between dose enhancement and GNP proximity to the nucleus.
Conclusion: The results show the importance of proximity of GNPs for radiation dose enhancement using a realistic GNP distribution. The understanding of dose enhancement characteristics on these parameters using clinically relevant energies can guide pre-clinical studies and advance GNP-aided radiation dose enhancement.
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