TY  - JOUR
AU  - Zhang, Tengda
AU  - Stengl, Christina
AU  - Derksen, Larissa
AU  - Palskis, Kristaps
AU  - Koritsidis, Konstantinos
AU  - Zink, Klemens
AU  - Adeberg, Sebastian
AU  - Major, Gerald
AU  - Weishaar, David
AU  - Theiß, Ulrike
AU  - Jin, Jing
AU  - Spadea, Maria Francesca
AU  - Theodoridou, Elpida
AU  - Hesser, Jürgen
AU  - Baumann, Kilian-Simon
AU  - Seco, Joao
TI  - Analysis of hydrogen peroxide production in pure water: Ultrahigh versus conventional dose-rate irradiation and mechanistic insights.
JO  - Medical physics
VL  - 51
IS  - 10
SN  - 0094-2405
CY  - College Park, Md.
PB  - AAPM
M1  - DKFZ-2024-01574
SP  - 7439-7452
PY  - 2024
N1  - #EA:E041#LA:E041# / 2024 Oct;51(10):7439-7452
AB  - Ultrahigh dose-rate radiation (UHDR) produces less hydrogen peroxide (H2O2) in pure water, as suggested by some experimental studies, and is used as an argument for the validity of the theory that FLASH spares the normal tissue due to less reactive oxygen species (ROS) production. In contrast, most Monte Carlo simulation studies suggest the opposite.We aim to unveil the effect of UHDR on H2O2 production in pure water and its underlying mechanism, to serve as a benchmark for Monte Carlo simulation. We hypothesized that the reaction of solvated electrons ( e aq -  e<sub>aq</sub><sup>−</sup>  ) removing hydroxyl radicals (•OH), the precursor of H2O2, is the reason why UHDR leads to a lower G-value (molecules/100 eV) for H2O2 (G[H2O2]), because: 1, the third-order reaction between e aq -  e<sub>aq</sub><sup>−</sup>  and •OH is more sensitive to increased instantaneous ROS concentration by UHDR than a two-order reaction of •OH self-reaction producing H2O2; 2, e aq -  e<sub>aq</sub><sup>−</sup>  has two times higher diffusion coefficient and higher reaction rate constant than that of •OH, which means e aq -  e<sub>aq</sub><sup>−</sup>  would dominate the competition for •OH and benefit more from the inter-track effect of UHDR. Meanwhile, we also experimentally verify the theory of long-lived radicals causing lower G(H2O2) in conventional irradiation, which is mentioned in some simulation studies.H2O2 was measured by Amplex UltraRed assay. 430.1 MeV/u carbon ions (50 and 0.1 Gy/s), 9 MeV electrons (600 and 0.62 Gy/s), and 200 kV x-ray tube (10 and 0.1 Gy/s) were employed. For three kinds of water (real hypoxic: 1
KW  - hydrogen peroxide (Other)
KW  - solvated electron (Other)
KW  - ultrahigh dose rate (Other)
KW  - water radiolysis (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:39092902
DO  - DOI:10.1002/mp.17335
UR  - https://inrepo02.dkfz.de/record/292066
ER  -