Deceleration processes of secondary electrons produced by a high-energy Auger electron in a biological context

Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Fujii, Keisuke; Watanabe, Ritsuko

doi:10.1080/09553002.2016.1195933

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…The X-ray spectrums were estimated according to the semiempirical model reported by Tucker et al [48]. We adapted an electron gamma shower (EGS) [49] mode for photon transport and an electron track structure mode (etsmode) [50][51][52][53][54][55] for electron transport in the PHITS calculation. It should be noted that the "etsmode" implemented in the PHITS code was verified from various endpoints including range, stopping power, nanodosimetry and double-strand break (DSB) yield [17].…”

Section: Monte Carlo Simulations Of X-ray and Electron Processesmentioning

confidence: 99%

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Matsuya

Nakano

Kai

et al. 2020

IJMS

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Complex DNA damage, defined as at least two vicinal lesions within 10–20 base pairs (bp), induced after exposure to ionizing radiation, is recognized as fatal damage to human tissue. Due to the difficulty of directly measuring the aggregation of DNA damage at the nano-meter scale, many cluster analyses of inelastic interactions based on Monte Carlo simulation for radiation track structure in liquid water have been conducted to evaluate DNA damage. Meanwhile, the experimental technique to detect complex DNA damage has evolved in recent decades, so both approaches with simulation and experiment get used for investigating complex DNA damage. During this study, we propose a simplified cluster analysis of ionization and electronic excitation events within 10 bp based on track structure for estimating complex DNA damage yields for electron and X-ray irradiations. We then compare the computational results with the experimental complex DNA damage coupled with base damage (BD) measured by enzymatic cleavage and atomic force microscopy (AFM). The computational results agree well with experimental fractions of complex damage yields, i.e., single and double strand breaks (SSBs, DSBs) and complex BD, when the yield ratio of BD/SSB is assumed to be 1.3. Considering the comparison of complex DSB yields, i.e., DSB + BD and DSB + 2BD, between simulation and experimental data, we find that the aggregation degree of the events along electron tracks reflects the complexity of induced DNA damage, showing 43.5% of DSB induced after 70 kVp X-ray irradiation can be classified as a complex form coupled with BD. The present simulation enables us to quantify the type of complex damage which cannot be measured through in vitro experiments and helps us to interpret the experimental detection efficiency for complex BD measured by AFM. This simple model for estimating complex DNA damage yields contributes to the precise understanding of the DNA damage complexity induced after X-ray and electron irradiations.

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Section: Monte Carlo Simulations Of X-ray and Electron Processesmentioning

confidence: 99%

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Matsuya

Nakano

Kai

et al. 2020

IJMS

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“…Since PHITS estimates the radiation track from the corresponding mean-free path without considering a constant time interval (i.e., 1 attosecond), we adopted a time-dependent variational Monte Carlo method, dynamic Monte Carlo code (DMCC). [23][24][25][26][27][28] The physical model for simulating electron dynamics by DMCC was implemented in etsmode, thus the validation using DMCC can be applied to the calculation results using etsmode. From the DMCC simulation, we obtained the gyration time and radius of the electrons in one period within the SMF.…”

Section: Methodsmentioning

confidence: 99%

“…For dealing with the above issues, Particle and Heavy Ion Transport code System (PHITS) 22 is appropriate because the dynamics of low-energy electrons down to 10 −3 eV in liquid water [23][24][25][26][27][28] can be analysed using the electron track-structure mode, etsmode, even in magnetic elds, where the types and the yields of DNA damage are determined based on the spatial patterns of atomic interactions. [29][30][31] In this study, we estimate the physics features of electron tracks (i.e., ranges, dose distributions, etc.)…”

Section: Introductionmentioning

confidence: 99%

Impact of the Lorentz Force on Electron Track Structure and Early DNA Damage Yields in Magnetic Resonance-Guided Radiotherapy

Yachi

Kai

Matsuya

et al. 2022

Preprint

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Magnetic resonance-guided radiotherapy (MRgRT) has been developed and installed in recent decades for external radiotherapy in several clinical facilities. The Lorentz force modulates dose distribution by charged particles in MRgRT; however, the impact by this force on low-energy electron track structure and early DNA damage induction remain unclear. In this study, we estimated features of electron track structure and biological effects in a static magnetic field (SMF) using a general-purpose Monte Carlo code, Particle and Heavy Ion Transport code System (PHITS) that enables us to simulate low-energy electrons down to 1 meV by track-structure mode. The macroscopic dose distributions by electrons above approximately 300 keV initial energy in liquid water are changed by both perpendicular and parallel SMFs against the incident direction, indicating that the Lorentz force plays an important role in calculating dose within tumours. Meanwhile, DNA damage estimation based on the spatial patterns of atomic interactions indicates that the initial yield of DNA double-strand breaks (DSBs) is independent of the SMF intensity. The DSB induction is predominantly attributed to the secondary electrons below a few tens of eV, which are not affected by the Lorentz force. Our simulation study suggests that treatment planning for MRgRT can be made with consideration of only changed dose distribution.

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“…However, these remain uncertain of the quality of radiation transport at the lower energy below sub-kiloelectron volt. On the other hand, Particle and Heavy Ion Transport code System (PHITS) can simulate the track structure of electrons in liquid water in the low energy range below sub-kilo electron volt [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

DNA strand breaks based on Monte Carlo simulation in and around the Lipiodol with flattening filter and flattening filter-free photon beams

Kawahara

Saito

Nakano

et al. 2022

Rep Pract Oncol Radiother.

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Deceleration processes of secondary electrons produced by a high-energy Auger electron in a biological context

Cited by 15 publications

References 27 publications

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Impact of the Lorentz Force on Electron Track Structure and Early DNA Damage Yields in Magnetic Resonance-Guided Radiotherapy

DNA strand breaks based on Monte Carlo simulation in and around the Lipiodol with flattening filter and flattening filter-free photon beams

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