H Lin1*, H Luo2,Y Zhao2,R Lu2,J Dai2,H Li2,J Jing1,X Guo1 (1)School of Physics, Hefei University of Technology, Hefei 230009, China; (2)School of Microelectronics, Hefei University of Technology, Hefei 230009, China

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  H Lin

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PO-GePV-T-107 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: To investigate the effect of direct ionizing radiation of different atomistic DNA models on Relative Biological Effectiveness (RBE) for electrons and protons.

Methods: The information of three typical DNAs from Protein Data Bank (PDB, http://rcsb.org) was used to build atomistic DNA models. The DNA damage and the RBE caused by low energy electrons and protons were studied based on Geant4-DNA low-energy physical model (dnaphysics option4). The energies from 0.4 to 10 keV for electrons and from 0.001 to 30MeV for protons were studied. The particle was assumed to be emitted from any location with any direction inside the DNA outline by uniform sampling of random number. The 1e7 electrons and 1e5 protons for any energy were simulated. The RBE was calculated by comparing SSB/DSB yields with those of 60Co. The batch process mode was adopted considering for lots of repetitive computing.

Results: There are different 60Co yields for different atomistic DNA models. The 60Co SSB/DSB yields are 80.45±3.51/1.64±0.10, 162.50±7.48/2.29±0.71 and 124.19±8.88/2.11±0.50 (GGybp)−1 for 1ZBB (4_601_167 Tetranucleosome), 1bna (B-DNA DODECAMER) and 1tsr (P53 CORE DOMAIN IN COMPLEX WITH DNA), respectively. The mean SSB/DSB RBEs calculated by its respective DNA model are 1.56±0.13/2.17±0.79 (1ZBB), 1.85±0.45/3.11±1.69 (1bna), and 1.81±0.37/2.77±1.46 (1tsr) for electrons, 2.95±0.81/6.47±5.10 (1ZBB), 2.10±0.49/9.32±6.31 (1bna), and 1.92±0.37/7.26±4.76 (1tsr) for protons for concerned energies. However if the DNA models were confused by each other, there will bring differences of 2.02 /1.29 times to SSB/DSB RBEs.

Conclusion: As far as the direct ionizing radiation is considered, the atomistic DNA model remarkably affects RBE value. It is better that RBE value labels acquisition from which type of DNA.And the precise radiobiological quantity should also consider these factors like DNA atoms number, structure and composition etc.

Funding Support, Disclosures, and Conflict of Interest: Supported by the university student innovation project of Hefei University of Technology (X202110359472; X202110359488)

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