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Journal Articles

Estimate of economic impact of atmospheric radiation storm associated with solar energetic particle events on aircraft operations

Saito, Susumu*; Wickramasinghe, N. K.*; Sato, Tatsuhiko; Shiota, Daiko*

Earth, Planets and Space (Internet), 73(1), p.57_1 - 57_10, 2021/12

 Times Cited Count:2 Percentile:72.01(Geosciences, Multidisciplinary)

By using an flight trajectory generation algorithm and the global effective dose rate (EDR) distribution calculated WASAVIES, the economic impacts of SEP events on aircraft operation, namely the flight path length, flight time, and fuel consumption, are estimated. The flight path length, flight time, and fuel consumption for a flight route from New York, US to Tokyo, Japan are estimated with constraints in flight routes to avoid the hazard of radiation and compared with those of the reference case without the SEP effects. Setting more flexible constraints in the flight route and generating optimal flight trajectories with minimal economic impacts by fully utilizing the global EDR distribution is the next step.

Journal Articles

Space weather benchmarks on Japanese society

Ishii, Mamoru*; Shiota, Daiko*; Tao, Chihiro*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Ishii, Takako*; Ichimoto, Kiyoshi*; Kataoka, Ryuho*; Koga, Kiyokazu*; Kubo, Yuki*; et al.

Earth, Planets and Space (Internet), 73(1), p.108_1 - 108_20, 2021/12

 Times Cited Count:1 Percentile:72.01(Geosciences, Multidisciplinary)

We surveyed the relationship between the scale of space weather events and their occurrence rate in Japan and we discussed the social impact of these phenomena during the Project for Solar-Terrestrial Environment Prediction (PSTEP). The information was compiled for domestic users of space weather forecasts for appropriate preparedness against space weather disasters. This paper gives a comprehensive summary of the survey, focusing on the fields of electricity, satellite operations, communication and broadcasting, satellite positioning usage, aviation, human space activity, and daily life on the Earth's surface, using the cutting-edge knowledge of space weather. Quantitative estimations of the economic impact of space weather events on electricity and aviation are also given.

Journal Articles

Track-structure mode for electrons, protons and carbon ions in the PHITS code

Matsuya, Yusuke; Kai, Takeshi; Ogawa, Tatsuhiko; Hirata, Yuho; Sato, Tatsuhiko

Hoshasen Kagaku (Internet), (112), p.15 - 20, 2021/11

Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo code enabling radiation kinetics, which is often used in diverse research fields, such as atomic energy, engineering, medicine and science. After released in 2010, the PHITS code has been developed to expand its functions and to improve its convenience. In the few years, track-structure mode has been introduced in PHITS that can simulate each atomic interaction by electrons, positions, protons and carbon ions in liquid water. Thanks to the development of track-structure mode, the latest PHITS code enables microscopic dose calculations by decomposing it to the scale of DNA. Aiming at realizing the track-structure mode with high precision, the further developments of electron and ion track-structure mode for arbitrary materials are recently ongoing. This review shows the development history and future prospect of PHITS track-structure mode, which can expect to be further applied to the research fields of atomic physics, radiation chemistry, and quantum life science.

Journal Articles

Technical Note: Validation of a material assignment method for a retrospective study of carbon-ion radiotherapy using Monte Carlo simulation

Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko

Journal of Radiation Research (Internet), 62(5), p.846 - 855, 2021/09

With the aim of developing a revaluation tool of treatment plan in carbon-ion radiotherapy using Monte Carlo (MC) simulation, we propose two methods; one is dedicated to identify realistic-tissue materials from a CT image with satisfying the well-calibrated relationship between CT numbers and stopping power ratio (SPR) provided by TPS, and the other is to estimate dose to water considering the particle- and energy-dependent SPR between realistic tissue materials and water. We validated these proposed methods by computing depth dose distribution in homogeneous and heterogeneous phantoms composed of human tissue materials and water irradiated by a 400 MeV/u carbon beam with 8 cm SOBP using a MC simulation code PHITS and comparing with results of conventional treatment planning system (TPS). Our result suggested that use of water as a surrogate of real tissue materials, which is adopted in conventional TPS, is inadequate for dose estimation from secondary particles because their production rates cannot be scaled by SPR of the primary particle in water. We therefore concluded that the proposed methods can play important roles in the reevaluation of the treatment plans in carbon-ion radiotherapy.

Journal Articles

Medical application of Particle and Heavy Ion Transport code System PHITS

Furuta, Takuya; Sato, Tatsuhiko

Radiological Physics and Technology, 14(3), p.215 - 225, 2021/09

Number of the PHITS users has steadily increased since 2010 from when it is officially counted. Among them, increase of new users in medical physics is outstanding. Many research works in medical physics using PHITS have been published and the applications are widely spread in different fields such as applications to different types of radiotherapy, shielding calculations of medical facilities, application to radiation biology, and research and development of medical tools. In this article, we will introduce useful functions for medical application in PHITS by referring to examples of various medical applications.

Journal Articles

Probabilistic risk assessment of solar particle events considering the cost of countermeasures to reduce the aviation radiation dose

Fujita, Moe*; Sato, Tatsuhiko; Saito, Susumu*; Yamashiki, Yosuke*

Scientific Reports (Internet), 11, p.17091_1 - 17091_9, 2021/09

 Times Cited Count:0

Radiation exposure to flight crews and passengers, which is called aviation exposure, is an important topic in radiological protection, particularly due to solar energetic particles (SEP). We assessed the risks against the counter measure costs to reduce SEP doses and dose rates for eight flight routes during five ground level enhancements (GLE). A four-dimensional dose-rate database developed by the Warning System for Aviation Exposure to Solar Energetic Particles, WASAVIES, was employed in the SEP dose evaluation. Our calculations suggest that GLE that is enough to request a change in flight conditions occurs once per 47 and 17 years respectively, in the case of following the dose and dose-rate regulations. The annual risks against the counter measure costs are up to around 1500 USD per long-distance and high-latitude flight.

Journal Articles

Reassessment of organ doses received by A-bomb survivors by precisely reproducing body dimensions of the Japanese in 1945

Sato, Tatsuhiko

Isotope News, (776), p.26 - 28, 2021/08

A Japan-U.S. joint project team was formed, comprising Nuclear Science and Engineering Center of JAEA, RERF, the University of Florida, and the U.S. National Cancer Institute. Members of this project team developed a new set of models of the human body (called phantoms) for adults, children, and pregnant women by precisely reproducing the standard body dimensions of Japanese people in 1945, modeled in detail with the latest CT images and other information. The project team also developed a method for more accurately estimating the organ doses of A-bomb survivors with these phantoms by utilizing the latest computational techniques such as PHITS, which were originated mainly by JAEA. Based on idealized conditions in hypothetical survivors, our initial comparisons of doses using the new phantoms and methods with doses derived from the current dosimetry system found that doses were generally consistent, although for some organs dose estimates could change by approximately $$pm$$15% at the maximum.

Journal Articles

Oxygen enhancement ratios of cancer cells after exposure to intensity modulated X-ray fields; DNA damage and cell survival

Matsuya, Yusuke; McMahon, S. J.*; Butterworth, K. T.*; Naijo, Shingo*; Nara, Isshi*; Yachi, Yoshie*; Saga, Ryo*; Ishikawa, Masayori*; Sato, Tatsuhiko; Date, Hiroyuki*; et al.

Physics in Medicine & Biology, 66(7), p.075014_1 - 075014_11, 2021/04

 Times Cited Count:0 Percentile:0.01(Engineering, Biomedical)

Hypoxic cancer cells within solid tumours show radio-resistance, leading to malignant progression in fractionated radiotherapy. When prescribing dose to tumours under heterogeneous oxygen pressure with intensity-modulated radiation fields, intercellular signalling could have an impact on radiosensitivity between in-field and out-of-field cells. However, the impact of hypoxia on radio-sensitivity under modulated radiation intensity remains uncertain. In this study, we investigate the impact of hypoxia on in-field and out-of-field radio-sensitivities using two types of cancer cells. These in vitro measurements indicate that hypoxia apparently impacts out-of-field cells, although the OER values in out-of-field cells were smaller compared to those for in-field and uniformly irradiated cells. These decreased radio-sensitivities of out-of-field cells were shown as a consistent tendency for both DSB and cell death endpoints, suggesting that radiation-induced intercellular communication is of importance in treatment planning with intensity-modulated radiotherapy.

Journal Articles

Verification of KURBUC-based ion track structure mode for proton and carbon ions in the PHITS code

Matsuya, Yusuke; Kai, Takeshi; Sato, Tatsuhiko; Liamsuwan, T.*; Sasaki, Kohei*; Nikjoo, H.*

Physics in Medicine & Biology, 66(6), p.06NT02_1 - 06NT02_11, 2021/03

 Times Cited Count:2 Percentile:74.69(Engineering, Biomedical)

A general-purpose Monte Carlo radiation transport simulation code, Particle and Heavy Ion Transport code System (PHITS), has the ability to handle diverse particle types over a wide range of energy. In PHITS version 3.20, ion track structure mode has been developed based on the algorithms in the KURBUC code, which enables to simulate the atomic interactions by primary ion and secondary particles (named as PHITS-KURBUC mode). In this study, we compared the range, radial dose distributions, and microdosimetric distributions calculated using the PHITS-KURBUC mode to the corresponding data obtained from the original KURBUC and from other studies. These comparative studies confirm the successful inclusion of the KURBUC code in the PHITS code. As results of the synergistic effect between the macroscopic and microscopic radiation transport codes, this implementation enabled the detailed calculation of the microdosimetric and nanodosimetric quantities under complex radiation fields, such as proton beam therapy with the spread-out Bragg peak. This PHITS-KURBUC mode is expected to pave the way for next-generation radiation researches, such as radiation physics, radiological protection, medical physics, and radiation biology.

Journal Articles

Individual dosimetry system for targeted alpha therapy based on PHITS coupled with microdosimetric kinetic model

Sato, Tatsuhiko; Furuta, Takuya; Liu, Y.*; Naka, Sadahiro*; Nagamori, Shushi*; Kanai, Yoshikatsu*; Watabe, Tadashi*

EJNMMI Physics (Internet), 8, p.4_1 - 4_16, 2021/01

 Times Cited Count:2 Percentile:90.15(Radiology, Nuclear Medicine & Medical Imaging)

An individual dosimetry system including the function for calculating EQDX was developed based on PHITS coupled with the microdosimetric kinetic model. It enables us to predict the therapeutic and side effects of TAT based on the clinical data largely available from conventional external radiotherapy.

Journal Articles

Recent progress in space weather research for cosmic radiation dosimetry

Sato, Tatsuhiko

Annals of the ICRP, 49(1_suppl.), p.185 - 192, 2020/12

The radiation environment in space is a complex mixture of particles of solar and galactic origin with a broad range of energies. For astronaut dose estimation, three sources must be considered, namely, galactic cosmic rays (GCR), trapped particles (TP), and solar energetic particles (SEP). More details about the radiation environment in space will be discussed at the symposium, together with the recent progresses on the space weather research for nowcasting and forecasting the astronaut doses due to SEP exposure.

Journal Articles

$$^{rm 208,207,206,nat}$$Pb(p,x)$$^{207}$$Bi and $$^{209}$$Bi(p,x)$$^{207}$$Bi excitation functions in the energy range of 0.04 - 2.6 GeV

Titarenko, Yu. E.*; Batyaev, V. F.*; Pavlov, K. V.*; Titarenko, A. Yu.*; Malinovskiy, S. V.*; Rogov, V. I.*; Zhivun, V. M.*; Kulevoy, T. V.*; Chauzova, M. V.*; Lushin, S. V.*; et al.

Nuclear Instruments and Methods in Physics Research A, 984, p.164635_1 - 164635_8, 2020/12

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

The paper presents the $$^{207}$$Bi production cross-sections measured by the direct gamma-spectrometry technique in the samples of lead enriched with isotopes 208, 207 and 206, as well as in the samples of natural lead and bismuth, irradiated by protons of 11 energies in the range from 0.04 to 2.6 GeV. The obtained experimental results are compared with the previous measurements, with the TENDL-2019 data-library evaluations and the simulated data by means of the high-energy transport codes MCNP6.1 (CEM03.03), PHITS (INCL4.6/GEM), and Geant4 (INCL++/ABLA). The observed discrepancies between model predictions and experimental data are discussed.

Journal Articles

Modernization of the DCHAIN-PHITS activation code with new features and updated data libraries

Ratliff, H.; Matsuda, Norihiro; Abe, Shinichiro; Miura, Takamitsu*; Furuta, Takuya; Iwamoto, Yosuke; Sato, Tatsuhiko

Nuclear Instruments and Methods in Physics Research B, 484, p.29 - 41, 2020/12

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

Journal Articles

Development of a new microdosimetric biological weighting function for the RBE$$_{10}$$ assessment in case of the V79 cell line exposed to ions from $$^{1}$$H to $$^{238}$$U

Parisi, 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:6 Percentile:85.91(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.

Journal Articles

Evaluation of RBE-weighted doses for various radiotherapy beams based on a microdosimetric function implemented in PHITS

Takada, Kenta*; Sato, Tatsuhiko; Kumada, Hiroaki*; Sakurai, Hideyuki*; Sakae, Takeji*

Journal of Physics; Conference Series, 1662, p.012004_1 - 012004_6, 2020/10

The University of Tsukuba has developed a treatment planning system (TPS) for boron neutron capture therapy (BNCT) that uses a Monte Carlo algorithm as a dose calculation engine. In the system, RBE-weighted dose can be also estimated using the microdosimetric function implemented in PHITS. In this study, we calculated the RBE-weighted doses for various radiation therapy beams. Comparison between the calculated results for different radiation therapy beams as well as verification of the calculated data will be presented at the meeting.

Journal Articles

Real-time ${{it in vivo}}$ dosimetry system based on an optical fiber-coupled microsized photostimulable phosphor for stereotactic body radiation therapy

Yada, Ryuichi*; Maenaka, Kazusuke*; Miyamoto, Shuji*; Okada, Go*; Sasakura, Aki*; Ashida, Motoi*; Adachi, Masashi*; Sato, Tatsuhiko; Wang, T.*; Akasaka, Hiroaki*; et al.

Medical Physics, 47(10), p.5235 - 5249, 2020/10

 Times Cited Count:4 Percentile:75.79(Radiology, Nuclear Medicine & Medical Imaging)

The ${{it in vivo}}$ dosimeter system is capable of real-time, accurate, and precise measurement under stereotactic body radiation therapy (SBRT) conditions. The probe is smaller than a conventional dosimeter, has excellent spatial resolution, and can be valuable in SBRT with a steep dose distribution over a small field. The developed PSP dosimeter system appears to be suitable for in vivo SBRT dosimetry.

Journal Articles

Dosimetric impact of a new computational voxel phantom series for the Japanese atomic bomb survivors; Methodological improvements and organ dose response functions

Sato, Tatsuhiko; Funamoto, Sachiyo*; Paulbeck, C.*; Griffin, K.*; Lee, C.*; Cullings, H.*; Egbert, S. D.*; Endo, Akira; Hertel, N.*; Bolch, W. E.*

Radiation Research, 194(4), p.390 - 402, 2020/10

 Times Cited Count:2 Percentile:0.01(Biology)

Owing to recent advances in computational dosimetry tools, it is desirable to update the dosimetry system for the atomic-bomb survivors as it was established by DS02. In the current study, we have investigated the possible impact of introducing not only the J45 phantom series but also various methodological upgrades to the DS02 dosimetry system. It was found that the anatomical improvement in the J45 phantom series is the most important factor leading to potential changes in survivor organ doses. In addition, this study established a series of response functions which allows for the rapid conversion of the unidirectional quasi-monoenergetic photon and neutron fluences to organ doses within the J45 adult phantoms. This system of response functions can be implemented within a revision to the DS02 dosimetry system and used for future updates to organ doses within the Life Span Study of the atomic-bomb survivors.

Journal Articles

Investigation of using a long-life electronic personal dosimeter for monitoring aviation doses of frequent flyers

Yasuda, Hiroshi*; Yajima, Kazuaki*; Sato, Tatsuhiko

Radiation Measurements, 134, p.106309_1 - 106309_4, 2020/06

 Times Cited Count:1 Percentile:39.17(Nuclear Science & Technology)

We have investigated an application of a recently developed electronic personal dosimeter (D-Shuttle) for aviation dosimetry. As results of measurements in four long-haul flights between Japan and Germany, the D-Shuttle indicated values were in the range of 25 to 30% of the total H$$^{*}$$(10) values estimated by a route-dose calculations program JISCARD EX. Though we need more measurements and analyses under different flight conditions to conclude, according to these results obtained so far, it would be possible to perform monitoring of the annual aviation doses of frequent flyers by using D-Shuttle on an individual basis.

Journal Articles

A Theoretical cell-killing model to evaluate oxygen enhancement ratios at DNA damage and cell survival endpoints in radiation therapy

Matsuya, Yusuke; Sato, Tatsuhiko; Nakamura, Rui*; Naijo, Shingo*; Date, Hiroyuki*

Physics in Medicine & Biology, 65(9), p.095006_1 - 095006_12, 2020/05

 Times Cited Count:1 Percentile:33.12(Engineering, Biomedical)

Radio-resistance induced under low oxygen pressure plays an important role in malignant progression in fractionated radiotherapy. For the general approach to predict cell killing under hypoxia, cell-killing models (e.g., the Linear-Quadratic model) have to be fitted to ${it in vitro}$ experimental survival data for both normoxia and hypoxia to obtain the oxygen enhancement ratio (OER). However, model parameters for every oxygen condition needs to be considered by model-fitting approaches. This is inefficient for fractionated irradiation planning. Here, we present an efficient model for fractionated radiotherapy the integrated microdosimetric-kinetic model including cell-cycle distribution and the OER at DNA double-strand break endpoint. The cell survival curves described by this model can reproduce the ${it in vitro}$ experimental survival data for both acute and chronic low oxygen concentrations. The OER$$_{DSB}$$ used for calculating cell survival agrees well with experimental DSB ratio of normoxia to hypoxia. This work provides biological effective dose (BED) under various oxygen conditions including its uncertainty, which can contribute to creating fractionated regimens for multi-fractionated radiotherapy. If the oxygen concentration in a tumor can be quantified by medical imaging, the present model will make it possible to estimate the cell-killing and BED under hypoxia in more realistic intravital situations.

Journal Articles

Impact of hydrided and non-hydrided materials near transistors on neutron-induced single event upsets

Abe, Shinichiro; Sato, Tatsuhiko; Kuroda, Junya*; Manabe, Seiya*; Watanabe, Yukinobu*; Liao, W.*; Ito, Kojiro*; Hashimoto, Masanori*; Harada, Masahide; Oikawa, Kenichi; et al.

Proceedings of IEEE International Reliability Physics Symposium (IRPS 2020) (Internet), 6 Pages, 2020/04

Single event upsets (SEUs) caused by neutrons have been recognized as a serious reliability problem for microelectronic devices on the ground level. In our previous work, it was found that hydride placed in front of the memory chip has considerably impact on SEU cross sections because H ions generated via elastic scattering of neutrons with hydrogen atoms are only emitted in a forward direction. In this study, the effect of components neighboring transistors on neutron-induced SEUs was investigated for 65-nm bulk SRAMs by using PHITS. It was found that the shape of the SEU cross section around few MeV comes from the thickness and the position of components placed in front of transistors when that components do not contains hydrogen atoms. By considering components adjoin memory cells in the test board used in the simulation, measured data at J-PARC BL10 were reproduced well. In addition, it was found that the effect of components neighboring transistors on neutron-induced SERs does not negligible in terrestrial environment.

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