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Update of the GEANT4-DNA Software for Simulation of Radiation Chemical Yield for Reactive Water Radiolysis Species at Different Temperature and PH

J Bian1, J Duran1, W Shin2, J Ramos-Mendez3, L Childress4, J Sankey4, J Seuntjens1,5, S Abbasinejad Enger*1,5,6, (1) Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada, (2) Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea, (3) Department of Radiation Oncology, University of California San Francisco, California, United States of America, (4) Department of Physics, McGill University, Montreal, Quebec, Canada, (5) Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada, (6) Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada


PO-GePV-T-271 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: The aim of this project was to update the GEANT4-DNA software to be able to simulate the radiation chemical yield for reactive water radiolysis species at different temperatures and pH values.

Methods: The GEANT4-DNA package was updated with the independent reaction times (IRT) method to simulate the G-values for hydrated electron and other reactive species at different physical parameters (temperature, pH values). The IRT method is a computational efficient method with the independent pairs approximation. In GEANT4-DNA package, the values of specific chemical parameters such as diffusion coefficient, reaction rates, water density and the Onsager radius, were replaced by the corresponding temperature-dependent polynomials. In this work, results for hydrated electron and other reactive species are presented. The temperature dependent G-values for hydrated electrons from 25℃ to 350℃ from were compared with values from published work.

Results: The G-values for reactive water radiolysis species were plotted as functions of time in nanoseconds. The G-values for hydrated electron, hydrogen peroxide, hydronium ion and hydroxyl ion decrease with temperature, while the G-values for hydrogen radical and molecular hydrogen increase with temperature. For pH values, The G-values for hydrated electron increase with pH values, while the G-values for hydrogen radical, hydrogen peroxide and hydronium ion decrease with pH values. The G-values for molecular hydrogen stay relatively stable with different pH values. The G-values of hydroxyl ion are also relatively stable except that the G-values at pH 11 increase rapidly over time. The differences in percentage between the G-values for hydrated electron and published values were less than 7%.

Conclusion: The GEANT4-DNA source code was successfully updated to obtain temperature dependent G-values.

Funding Support, Disclosures, and Conflict of Interest: This research was conducted as part of MEDTEQ+ activities,thanks to the financial support of the Ministry of Economy and Innovation - PSOv2b program, cofounded by TransMedTech (Canada First Research Excellence Fund), Mitacs, the MUHC Foundation and Varian Medical Systems. Thanks to funding from Canada Research Chairs Program (grant # 252135).


Monte Carlo, Radiation Detectors, Chemical Dosimetry


TH- Radiation Dose Measurement Devices: Development (new technology and techniques)

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