Effect of FLASH dose-rate and oxygen concentration in the production of H 2 O 2 in cellular-like media versus water: a Monte Carlo track-structure study.
| Autor: | D-Kondo JN; Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero Street, San Francisco, CA 94143, USA, San Francisco, California, 94143, UNITED STATES., Borys D; Institute of Automatic Control, Silesian University of Technology, ul. Akademicka 16, Gliwice, 44-100, POLAND., Rucinski A; Institute of Nuclear Physics PAS, Walerego Eljasza-Radzikowskiego 152, Krakow, 31-342, POLAND., Brzozowska B; Biomedical Physics Division, University of Warsaw Faculty of Physics, Pasteura 5, Warszawa, 00-681, POLAND., Masilela TAM; Radiation Oncology, University of California San Francisco, 1600 Divisadero, San Francisco, California, 94115, UNITED STATES., Grochowska-Tatarczak M; University of Warsaw Faculty of Physics, Ludwika Pasteura 5, 02-093 Warszawa, Warszawa, 00-681, POLAND., Węgrzyn M; Silesian University of Technology Faculty of Automatic Control Electronics and Computer Science, Akademicka 16, Gliwice, PL, 44-100, Gliwice, Śląskie, 44-100, POLAND., Ramos-Mendez JA; Department of Oncology Radiation, University of California San Francisco, 1600 Divisadero Street, Suite HM006, San Francisco, California, 94143, UNITED STATES. |
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| Jazyk: | angličtina |
| Zdroj: | Physics in medicine and biology [Phys Med Biol] 2025 Jan 02. Date of Electronic Publication: 2025 Jan 02. |
| DOI: | 10.1088/1361-6560/ada517 |
| Abstrakt: | To study the effect of dose-rate in the time evolution of chemical yields produced in pure water versus a cellular-like environment for FLASH radiotherapy research.
A version of TOPAS-nBio with Tau-Leaping algorithm was used to simulate the homogenous chemistry stage of water radiolysis using three chemical models: 1) liquid water model that considered scavenging of eaq-, H● by dissolved oxygen; 2) Michaels & Hunt model that considered scavenging of ●OH, eaq-, and H● by biomolecules existing in cellular environment; 3) Wardman model that considered model 2) and the chemical repair enzyme glutathione (GHS). H2O2 concentrations at conventional and FLASH dose-rates were compared with published measurements. Model 3) was used to estimate DNA single-strand break (SSB) yields and compared with published data. SSBs were estimated from simulated yields of DNA hydrogen abstraction and attenuation factors to account for the scavenging capacity of the medium. The simulation setup consisted of monoenergetic protons (100 MeV) delivered in pulses at conventional (0.2857Gy s⁻¹) and FLASH (500Gy s⁻¹) dose rates. Dose varied from 5-20Gy, and oxygen concentration from 10µM-1mM.
At the steady state, for model 1), H2O2 concentration differed by 81.5%±4.0% between FLASH and conventional dose-rates. For models 2) and 3) the differences were within 8.0%±4.8%, and calculated SSB yields agreed with published data within 3.8%±1.2%. A maximum oxygen concentration difference of 60% and 50% for models 2) and 3) between conventional and FLASH dose-rates was found between 2106 and 91013 ps for 20 Gy of absorbed dose.
The findings highlight the importance of developing more advanced cellular models to account for both the chemical and biological factors that comprise the FLASH effect. It was found that differences between pure water and cellular environment models were significant and extrapolating results between the two should be avoided. Observed differences call for further experimental investigation. (© 2025 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.) |
| Databáze: | MEDLINE |
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