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Journal Articles

Implementation of simplified stochastic microdosimetric kinetic models into PHITS for application to radiation treatment planning

Sato, Tatsuhiko; Hashimoto, Shintaro; Inaniwa, Taku*; Takada, Kenta*; Kumada, Hiroaki*

International Journal of Radiation Biology, 97(10), p.1450 - 1460, 2021/10

 Times Cited Count:0 Percentile:0.01(Biology)

The stochastic microdosimetric kinetic (SMK) model is one of the most sophisticated and precise models used in the estimation of the relative biological effectiveness of carbon-ion radiotherapy (CRT) and boron neutron capture therapy (BNCT). Through the introduction of Taylor expansion (TE) or fast Fourier transform (FFT), we developed two simplified SMK models and implemented them into the Particle and Heavy Ion Transport code System (PHITS). This study enables the instantaneous calculation of the equieffective dose for CRT and BNCT, considering their cellular-scale dose heterogeneities. Treatment-planning systems that use the improved PHITS as a dose-calculation engine are under development.

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

Establishment of reasonable 2-D model to investigate heat transfer and flow characteristics by using scale model of vessel cooling system for HTTR

Takada, Shoji; Ngarayana, I. W.*; Nakatsuru, Yukihiro*; Terada, Atsuhiko; Murakami, Kenta*; Sawa, Kazuhiro*

Mechanical Engineering Journal (Internet), 7(3), p.19-00536_1 - 19-00536_12, 2020/06

In this study reasonable 2D model was established by using FLUENT for start-up of analysis and evaluation of heat transfer flow characteristics in 1/6 scale model of VCS for HTTR. By setting up pressure vessel temperature around 200$$^{circ}$$C about relatively high ratio of heat transfer via natural convection in total heat removal around 20-30%, which is useful for code to experiment benchmark in the aspect to confirm accuracy to predict temperature distribution of components which is heated up by natural convection flow. The numerical results of upper head of pressure vessel by the $$kappa$$-$$omega$$-SST intermittency transition model, which can adequately reproduce the separation, re-adhesion and transition, reproduced the test results including temperature distribution well in contrast to those by the $$kappa$$-$$varepsilon$$ model in both cases that helium gas is evacuated or filled in the pressure vessel. It was emerged that any local hot spot did not appear on the top of upper head of pressure vessel where natural convection flow of air is separated in both cases. In addition, the plume of high temperature helium gas generated by the heating of heater was well mixed in the upper head and uniformly heated the inner surface of upper head without generating hot spots.

Journal Articles

Establishment of numerical model to investigate heat transfer and flow characteristics by using scale model of vessel cooling system for HTTR

Takada, Shoji; Ngarayana, I. W.*; Nakatsuru, Yukihiro*; Terada, Atsuhiko; Murakami, Kenta*; Sawa, kazuhiko*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 13 Pages, 2019/05

In the loss of core cooling test using HTTR, a technical issue is to improve prediction accuracy of temperature distribution of components in vessel cooling system (VCS). An establishment of reasonable 2D model was started by using numerical code FLUENT, which was validated using the test data by 1/6 scale model of VCS for HTTR. The pressure vessel (PV) temperature was set around 200$$^{circ}$$C attributed to relatively high ratio of natural convection heat transfer around 20% in total heat removal, which is useful for code to experiment benchmark to improve prediction accuracy. It is necessary to confirm heat transfer flow characteristics around the top of PV which is heated up by natural convection flow which was considered to be affected by separation, re-adhesion and transition flow. The k-$$omega$$-SST model was selected for turbulent calculation attributed to predict the effects mentioned above adequately. The numerical results using the k-$$omega$$-SST model reproduced the temperature distribution of PV especially the top region which is considered to be affected by separation, re-adhesion and transition flow in contract to that using k-$$varepsilon$$ model which does not account the effects.

Journal Articles

Validation of the physical and RBE-weighted dose estimator based on PHITS coupled with a microdosimetric kinetic model for proton therapy

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

Journal of Radiation Research, 59(1), p.91 - 99, 2018/01

 Times Cited Count:22 Percentile:91.11(Biology)

Evaluation of the relative biological effectiveness (RBE)-weighted dose is indispensable in the treatment planning of proton and carbon ion therapies. In this study, we validate the RBE-weighted dose calculated by microdosimetric kinetic model (MKM) in tandem with the Monte Carlo particle transport code PHITS for proton therapy using the full simulation geometry for the beam line of the Proton Medical Research Center at the University of Tsukuba. The physical dose and RBE-weighted dose on the central axis for a 155 MeV monoenergetic and spread-out Bragg peak beam of 60 mm width are evaluated by the method. The calculated results generally agree with the corresponding experimental data very well, though overestimations by approximately 3.2% and 15% at the maximum are observed for the physical and RBE-weighted doses, respectively. This research completes the computational microdosimetric approach based on a combination of PHITS and MKM for all types of radiotherapy that require RBE evaluations.

Oral presentation

Significance and overview of basic safety principles on earthquake engineering for nuclear power plants, 2; Overview of basic safety principles on earthquake engineering for NPP

Takata, Takashi; Takada, Tsuyoshi*; Narumiya, Yoshiyuki*; Kamiya, Masanobu*; Jimbo, Masakazu*; Muta, Hitoshi*; Hayashi, Kentaro*

no journal, , 

Since earthquake surely takes place in Japan, safety on nuclear power plant (NPP) against earthquake is one of the most important issue. In April 2016, a research council of "Basic Safety Principles on Earthquake Engineering for Nuclear Power Plants" was established in Japan Association for Earthquake Engineering (JAEE) to clarify a basic concept and a practice of the safety principles among a mature discussion by engineers in a wide range of nuclear safety and earthquake engineering fields. In the present report, the summery of the basic safety principles is introduced and a sufficient exchange of views will be conducted through the session.

Oral presentation

An Optimization study on neutronic performance of target shape at J-PARC MLF TS2

Harada, Masahide; Sugihara, Kenta*; Teshigawara, Makoto; Takada, Hiroshi; Ikeda, Yujiro

no journal, , 

no abstracts in English

Oral presentation

Significance and overview of basic safety principles on earthquake engineering for nuclear power plants, 2; Overview of basic safety principles on earthquake engineering for NPP

Takata, Takashi; Takada, Tsuyoshi*; Narumiya, Yoshiyuki*; Kamiya, Masanobu*; Jimbo, Masakazu*; Muta, Hitoshi*; Hayashi, Kentaro*

no journal, , 

The research committee on "Basic Safety Principles on Earthquake Engineering" was established in Japan Association for Earthquake Engineering (JAEE) to propose the basic safety principles on earthquake engineering for nuclear power plants (NPPs) based on defense in depth and also risk concept. In the committee, three working groups were also established. In working group 1 (WG1), which was parallel established as a subcommittee of "Basic Safety Principles on Earthquake Engineering" in Atomic Energy Society of Japan (AESJ), the contents of the basic safety principles on earthquake engineering has been discussed and the material for discussion has been summarized. This paper summarizes the basic principles and points of contention through the discussion.

Oral presentation

Macro- and microdosimetry for BNCT based on PHITS

Sato, Tatsuhiko; Masunaga, Shinichiro*; Takada, Kenta*; Kumada, Hiroaki*; Hamada, Nobuyuki*

no journal, , 

In the treatment planning of BNCT, the absorbed doses and photon-isoeffective doses deposited by boron, nitrogen, hydrogen, and photon components are separately calculated. We have newly developed a method for evaluating the photon-isoeffective doses based on Particle and Heavy Ion Transport code System PHITS. The model will be implemented into our treatment planning system, as part of the Tsukuba plan.

Oral presentation

Estimation of photon-isoeffective and RBE-weighted doses in the accelerator-based neutron field

Sato, Tatsuhiko; Masunaga, Shinichiro*; Takada, Kenta*; Kumada, Hiroaki*; Hamada, Nobuyuki*

no journal, , 

In this study, the depth distributions of the two types of dose, photon-isoeffective dose and RBE-weighted dose, in a phantom placed at an accelerator-based BNCT field were calculated using Particle and Heavy Ion Transport code System, PHITS, coupled with an extended stochastic microdosimetric kinetic model. Compared with the corresponding RBE-weighted dose, the calculated photon-isoeffective dose was larger at lower absorbed dose and was smaller at higher absorbed dose, primarily due to the consideration of the dose dependence of RBE.

Oral presentation

Variation of photon-isoeffective dose due to the selection of the reference radiation

Sato, Tatsuhiko; Masunaga, Shinichiro*; Takada, Kenta*; Kumada, Hiroaki*; Hamada, Nobuyuki*

no journal, , 

Variation of photon-isoeffective dose due to the selection of the reference radiation will be discussed at the meeting.

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