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assessment in case of the V79 cell line exposed to ions from 
H to 
UParisi, A.*; Sato, Tatsuhiko; Matsuya, Yusuke; Kase, Yuki*; Magrin, G.*; Verona, C.*; Tran, L.*; Rosenfeld, A.*; Bianchi, A.*; Olko, P.*; et al.
Physics in Medicine & Biology, 65(23), p.235010_1 - 235010_20, 2020/12
Times Cited Count：24 Percentile：88.01(Engineering, Biomedical)A new biological weighting function (IBWF) is proposed to phenomenologically relate microdosimetric lineal energy probability density distributions with the relative biological effectiveness (RBE) for the in vitro clonogenic cell survival (survival fraction = 10%) of the most commonly used mammalian cell line, i.e. the Chinese hamster lung fibroblasts (V79). The RBE values assessed by the IBWF were found to be consistent and in good agreement with the ones calculated in combination with computer-simulated microdosimetric spectra, with an average relative deviation of 0.8% and 5.7% for H and C ions respectively.
Hirayama, Ryoichi*; Uzawa, Akiko*; Takase, Nobuhiro*; Matsumoto, Yoshitaka*; Noguchi, Miho; Koda, Kana*; Ozaki, Masakuni*; Yamashita, Kei*; Li, H.*; Kase, Yuki*; et al.
Mutation Research; Genetic Toxicology And Environmental Mutagenesis, 756(1-2), p.146 - 151, 2013/08
Times Cited Count：24 Percentile：60.91(Biotechnology & Applied Microbiology)Sato, Tatsuhiko; Watanabe, Ritsuko; Kase, Yuki*; Tsuruoka, Chizuru*; Suzuki, Masao*; Furusawa, Yoshiya*; Niita, Koji*
Radiation Protection Dosimetry, 143(2-4), p.491 - 496, 2011/02
Times Cited Count：33 Percentile：91.34(Environmental Sciences)We reanalyzed the survival fraction data, using the microdosimetric-kinetic (MK) model implemented in the PHITS code. It is found from the analysis that the MK model successfully accounts for the cell survival-fractions under a variety of irradiation conditions, using only y* parameter.
Hirayama, Ryoichi*; Uzawa, Akiko*; Matsumoto, Yoshitaka*; Noguchi, Miho; Kase, Yuki*; Takase, Nobuhiro*; Ito, Atsushi*; Koike, Sachiko*; Ando, Koichi*; Okayasu, Ryuichi*; et al.
Radiation Protection Dosimetry, 143(2-4), p.508 - 512, 2011/02
Times Cited Count：14 Percentile：71.79(Environmental Sciences)We studied double-strand breaks (DSB) induction and rejoining in clamped and non-clamped transplanted tumours in mice leg after exposure to 80 keV/
m carbon ions and X-rays. The yields of DSB in the tumours were analysed by a static-field gel electrophoresis. The OER of DSB after X-rays was 1.68, and this value was not changed after 1 h rejoining time (1.40). These damages in oxygenated conditions were rejoined 60-70% within 1 h in situ. No difference was found between the exposure to X-rays and carbon ions for the induction and rejoining of DSB. Thus, the values of OER and rejoined fraction after exposure to carbon ions were similar to those after X-rays, and the calculated relative biological effectivenesses of carbon ion were around 1 under both oxygen conditions. The yields of DSB in vivo depend on exposure doses, oxygen conditions and rejoining time, but not on the types of radiation quality.
Hirayama, Ryoichi*; Matsumoto, Yoshitaka*; Kase, Yuki*; Noguchi, Miho; Ando, Koichi*; Ito, Atsushi*; Okayasu, Ryuichi*; Furusawa, Yoshiya*
Radiation Physics and Chemistry, 78(12), p.1175 - 1178, 2009/12
Times Cited Count：12 Percentile：62.2(Chemistry, Physical)The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/mm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52 %. We conclude that OH radical mediated indirect action still has a half in total contribution on cell killing under hypoxic condition.
Sato, Tatsuhiko; Kase, Yuki*; Watanabe, Ritsuko; Niita, Koji*; Sihver, L.*
Hoshasen Kagaku, 52(2), p.47 - 53, 2009/02
We improved the particle transport simulation code PHITS to be capable of estimating the microdosimetric PDs in macroscopic area, by means of incorporating a mathematical function that can instantaneously calculate the PDs around the trajectory of HZE particles with precision equivalent to a microscopic track-structure simulation. A new method for estimating biological dose, a product of physical dose and RBE, from charged-particle therapy was established, using the improved PHITS coupled with a microdosimetric kinetic model.
Hirayama, Ryoichi*; Ito, Atsushi*; Tomita, Masanori*; Tsukada, Teruyo*; Yatagai, Fumio*; Noguchi, Miho; Matsumoto, Yoshitaka*; Kase, Yuki*; Ando, Koichi*; Okayasu, Ryuichi*; et al.
Radiation Research, 171(2), p.212 - 218, 2009/02
Times Cited Count：119 Percentile：95.63(Biology)The biological effects of radiation originate principally in damages to DNA. DNA damages by X-rays as well as heavy ions are induced by a combination of direct and indirect actions. The contribution of indirect action in cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide (DMSO), which suppresses indirect action without affecting direct action. Exponentially growing Chinese hamster V79 cells were exposed to high-LET radiations of 20 to 2106 keV/m in the presence or absence of DMSO and their survival was determined using a colony formation assay. The contribution of indirect action to cell killing decreased with increasing LET. However, the contribution did not reach zero even at very high LETs and was estimated to be 32% at an LET of 2106 keV/m. Therefore, even though the radiochemically estimated G value of OH radicals was nearly zero at an LET of 1000 keV/m, indirect action by OH radicals contributed to a substantial fraction of the biological effects of high-LET radiations. The RBE determined at a survival level of 10% increased with LET, reaching a maximum value of 2.88 at 200 keV/m, and decreased thereafter. When the RBE was estimated separately for direct action (RBE(D)) and indirect action (RBE(I)); both exhibited an LET dependence similar to that of the RBE, peaking at 200 keV/m. However, the peak value was much higher for RBE(D) (5.99) than RBE(I) (1.89). Thus direct action contributes more to the high RBE of high-LET radiations than indirect action does.
Sato, Tatsuhiko; Kase, Yuki*; Watanabe, Ritsuko; Niita, Koji*; Sihver, L.*
Radiation Research, 171(1), p.107 - 117, 2009/01
Times Cited Count：83 Percentile：91.05(Biology)A new method for estimating biological dose from charged-particle therapy was established, using the improved PHITS coupled with a microdosimetric kinetic model. In the method, the biological dose can be determined by multiplying the physical dose by the RBE for a surviving fraction of tumor cells, which is estimated from the saturation-corrected dose-mean lineal energy y* calculated by the improved PHITS. The accuracy of the biological dose estimated by this method was reliably verified by comparing the calculated physical doses and RBE values with the corresponding experimental data obtained by irradiating a slab phantom with the spread-out Bragg peak beams as well as several types of mono-energetic HZE particles. The simulation technique established in this study will help to optimize the treatment planning of charged-particle therapy for maximizing the therapeutic effect on tumor while minimizing unintended harmful effects on surrounding normal tissues.
Sato, Tatsuhiko; Kase, Yuki*; Watanabe, Ritsuko; Niita, Koji*
no journal, ,
We improved the particle transport simulation code PHITS, providing it with the capability of estimating the microdosimetric PDs in a macroscopic framework, by incorporating a mathematical function that can instantaneously calculate the PDs around the trajectory of HZE particles with precision equivalent to a microscopic track-structure simulation. A new method for estimating biological dose, the product of physical dose and RBE, from charged-particle therapy was established, using the improved PHITS coupled with a microdosimetric kinetic model. The simulation technique established in this study will help to optimize the treatment planning of charged-particle therapy, thereby maximizing the therapeutic effect on tumor while minimizing unintended harmful effects on surrounding normal tissues.
Sato, Tatsuhiko; Kase, Yuki*; Watanabe, Ritsuko; Niita, Koji*; Sihver, L.*
no journal, ,
We have established a new method for simultaneously estimating biological doses and dose equivalents inside the whole human body, using the particle and heavy ion transport code system PHITS. The detailed procedures for establishing this dose-estimation method were described elsewhere. At the meeting, we will thus focus on its applicability to the treatment planning of charged-particle therapy, showing the calculated results of biological doses and dose equivalents in several tissues for various irradiation conditions by changing the incident particle charges and energies, the structure of upstream apparatuses, and tumor locations.
Sato, Tatsuhiko; Kase, Yuki*; Watanabe, Ritsuko; Niita, Koji*
no journal, ,
We improved the 3-dimensional particle transport simulation code, PHITS, providing it with the capability to estimate the microdosimetric PDs in a macroscopic framework by incorporating a mathematical function that can instantaneously calculate the PDs around the trajectory of HZE particles with a precision equivalent to a microscopic track-structure simulation. A new method for estimating biological dose from charged-particle therapy was established using the improved PHITS coupled with a microdosimetric kinetic (MK) model.
Sato, Tatsuhiko; Watanabe, Ritsuko; Kase, Yuki*; Tsuruoka, Chizuru*; Suzuki, Masao*; Furusawa, Yoshiya*; Niita, Koji*
no journal, ,
It is found from the calculation that the biological doses vary with the cell type by approximately 8 percents, but their depth distributions were almost independent of the cell type.
Hirayama, Ryoichi*; Matsumoto, Yoshitaka*; Uzawa, Akiko*; Takase, Nobuhiro*; Tsuruoka, Chizuru*; Wada, Mami*; Noguchi, Miho; Kase, Yuki*; Matsufuji, Naruhiro*; Ito, Atsushi*; et al.
no journal, ,
The contribution of indirect action mediated by OH radicals in cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide (DMSO), which suppresses indirect action of radiation without affecting direct action. Exponentially growing Chinese hamster ovary cells under oxic and hypoxic conditions were exposed to X-rays and iron ions having a dose-averaged LET at 200 keV/micrometer in the presence or absence of DMSO, and the cell survival was determined using the colony formation assay. The contributions of indirect action of 76% and 50% were found for X-rays under oxic and hypoxic conditions, respectively. In contrast, the contributions of indirect action for iron ions were estimated to be 42% and 32%. The RBE values were 2.8 for oxic and 5.3 for hypoxic, and the OER values were 2.8 for X-rays and 1.5 for iron ions. When the RBE and OER were estimated separately for direct action (RBE(D) and OER(D)) and indirect action (RBE(I) and OER(I)); the RBE(D) was larger than RBE(I) under both normal and low oxygen concentrations. The OER(D) values for both X-rays and iron ions were lower than that for OER(I). Thus, direct action of radiation gives a remarkably higher RBE and lower OER for cell killing than indirect action. It is possible that particle beams may be highly effective in treating cancer if the particle therapy can only use the portion of direct action out of total radiation actions; this would be exemplified by the usage of radioactive 9C-ion beams and boron neutron capture.
