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Sato, Tatsuhiko; Furuta, Takuya; Sasaki, Hidetaka*; Watabe, Tadashi*
EJNMMI Physics (Internet), 12, p.28_1 - 28_16, 2025/03
Times Cited Count：0Hizukuri, Kyoko*; Fujibuchi, Toshio*; Han, D.*; Arakawa, Hiroyuki*; Furuta, Takuya
Radiological Physics and Technology, 18(1), p.196 - 208, 2025/03
One of the radiation protection measures for medical personnel engaged in X-ray fluoroscopy is the use of radiation-protective plates and a simulation tool to evaluate effect of the plates is desired. Monte Carlo simulation has an advantage of being able to accurately calculate the interaction between radiations and various objects present in the X-ray room. However, Monte Carlo simulation has a disadvantage of being computationally time-consuming. Therefore, we developed a new simplified method to calculate the dose distribution in a short time with the presence of protective plates using pre-computed directional vectors (SCV). Using the Monte Carlo code PHITS, we simulated the ambient dose equivalent distribution the X-ray fluoroscopy room without the presence of protective plates. Assuming the dose at each voxel was all contributed from radiations in the direction indicated by the directional vector, the shielding effect of the protective plates for the dose at the voxel was determined whether the line toward backtrace of the directional vector has a intersect with the protective plate or not. With SCV, the computational time for the whole dose distribution with the presence of a protective plate was reduced approximately 1/6000 of the full PHITS simulation keeping the good accuracy to evaluate the effect of the plate.
Lu-DOTATATE peptide receptor radionuclide therapyMiwa, Kenta*; Kakino, Ryo*; Sato, Tatsuhiko; Furuta, Takuya; Miyaji, Noriaki*; Yamao, Tensho*; Yamashita, Kosuke*; Terauchi, Takeshi*
Physical and Engineering Sciences in Medicine, 9 Pages, 2025/00
Radiotherapy package based on Particle and Heavy Ion Transport code System (RT-PHITS) enables to calculate the 3-dimensional dose distribution inside patients using their individual SPECT/CT images coupled with the Monte Carlo radiation transport simulation. The objective of this study is to evaluate the feasibility of individual dosimetry based on RT-PHITS for patients after Lu-DOTATATE peptide receptor radionuclide therapy.
Shigyo, Nobuhiro*; Furuta, Takuya; Iwamoto, Yosuke
JAEA-Conf 2024-002, 216 Pages, 2024/11
JAEA-Conf-2024-002.pdf:24.29MB
The 2023 Symposium on Nuclear Data was held at Tokai Industry and Information Plaza "iVil" on November 15-17, 2023. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) in cooperation with Radiation Engineering Division of AESJ, North Kanto Branch of AESJ, Investigation Committee on Nuclear Data in AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, and High Energy Accelerator Research Organization. In the symposium, tutorials "Overview of the nuclear data processing code, FRENDY version 2" was proposed and held. Two sessions of lectures and discussions were held: "Recent Topics on Nuclear Data and Particle and Heavy Ion Transport code System (PHITS)". In addition, recent research progress on experiments, nuclear theory, evaluation, benchmark, and applications were presented in the poster session. The total number of participants was 108 participants. Each oral and poster presentation was followed by an active question and answer session. This report consists of a total of 36 papers including 17 oral and 19 poster presentations.
Ogawa, Tatsuhiko; Hirata, Yuho; Matsuya, Yusuke; Kai, Takeshi; Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Furuta, Takuya; Abe, Shinichiro; Matsuda, Norihiro; et al.
EPJ Nuclear Sciences & Technologies (Internet), 10, p.13_1 - 13_8, 2024/11
The latest updates on PHITS, a versatile radiation transport code, focusing specifically on track-structure models are presented. Track structure calculations are methods used to simulate the movement of charged particles while explicitly considering each atomic reaction. Initially developed for radiation biology, these calculation methods aimed to analyze the radiation-induced damage to DNA and chromosomes. Several track-structure calculation models, including PHITS-ETS, PHITS-ETS for Si, PHITS-KURBUC, ETSART, and ITSART, have been developed and implemented to PHITS. These models allow users to study the behavior of various particles at the nano-scale across a wide range of materials. Furthermore, potential applications of track-structure calculations have also been proposed so far. This collection of track-structure calculation models, which encompasses diverse conditions, opens up new avenues for research in the field of radiation effects.
Sato, Kaoru; Furuta, Takuya; Satoh, Daiki; Tsuda, Shuichi
PLOS ONE (Internet), 19(10), p.e0309753_1 - e0309753_26, 2024/10
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)The authors previously developed the adult male (JM-103) and female (JF-103) voxel phantoms with standard Japanese body sizes for dose assessment of radiation accidents and medical exposures. However, JM-103 and JF-103 were not applicable to dose assessment considering posture at the time of exposure due to limitations in description format and resolution. In this study, we developed the polygon mesh-type adult Japanese phantoms (male: JPM, female: JPF) based on JM-103 and JF-103. The detailed models of skin and lens with radiosensitive regions less than 1 mm thick were incorporated into JPM and JPF. The effective doses, and skin and lens (entire and radiosensitive regions) doses were calculated for external irradiation with photons or electrons in anterior-posterior geometry. It was confirmed that dose analysis results by JPM and JPF were consistent with the previous reports. In the future, we will develop a detailed dose assessment method for individuals, taking into account their postures at the time of exposure, by applying the posture deformation technique currently under development to the JPM and JPF.
and 
study of biological effects on cancer cells in the presence of metallic materials during radiotherapyNagano, Takuya*; Matsuya, Yusuke; Kaida, Atsushi*; Nojima, Hitomi*; Furuta, Takuya; Sato, Kaoru; Yoshimura, Ryoichi*; Miura, Masahiko*
Journal of Radiation Research (Internet), 65(5), p.628 - 639, 2024/09
Times Cited Count：0 Percentile：0.00(Biology)In X-ray therapy, radiation regimen is planned to eliminate tumors while minimizing side effects on normal tissue. When irradiating the oral cavity, which includes dental metallic crowns, intense mucositis can occasionally be induced. However, the mechanism underlying the radiosensitization remains unclear. In this study, we investigated the radiosensitization mechanism using cell experiments and computational simulations. As a result, the enhancement ratio observed in the cell experiments was 1.2-1.4, which was found to be predominately attributed to local dose increase near metal. On the other hand, as a result of dose evaluation based on CT images as a preclinical test, it was found that the dose increase was underestimated due to the complex anatomical structure of the human body, and microscopic dose evaluation was necessary. This outcome contributes to the precise understanding of side effects on normal cells around metals.
Ishikawa, Akihisa; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Hashimoto, Shintaro; Hirai, Yuta*; Sato, Tatsuhiko
Radiological Physics and Technology, 17(2), p.553 - 560, 2024/06
Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuya, Yusuke; Matsuda, Norihiro; Hirata, Yuho; et al.
Journal of Nuclear Science and Technology, 61(1), p.127 - 135, 2024/01
Times Cited Count：119 Percentile：99.97(Nuclear Science & Technology)The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo radiation transport code that can simulate the behavior of most particle species with energies up to 1 TeV (per nucleon for ions). Its new version, PHITS3.31, was recently developed and released to the public. In the new version, the compatibility with high-energy nuclear data libraries and the algorithm of the track-structure modes have been improved. In this paper, we summarize the upgraded features of PHITS3.31 with respect to the physics models, utility functions, and application software introduced since the release of PHITS3.02 in 2017.
Furuta, Takuya
Isotope News, (787), p.20 - 23, 2023/06
Carbon ion radiotherapy has an advantage over conventional radiotherapy such that its superior dose concentration on the tumor helps to reduce unwanted dose to surrounding normal tissues. Nevertheless, a little dose to normal tissues, which is a potential risk of secondary cancer, is still unavoidable. In the current dose assessment, however, only assessment around target volume is performed for the tumor control and prevention of acute radiation injury of fatal organs. We therefore developed a system called RT-PHITS for CIRT to reproduce the carbon ion radiotherapy including the production and transport of secondary particles based on treatment planning data using PHITS. Using this system, whole-body dose assessment of patients in the past carbon ion radiotherapy can be performed. By comparing the dose assessment to the epidemiologic records of the patients, the relation between dose exposure of non-target organs and incidence of side effects such as secondary cancer will be elucidated.
Sabri, A. H. A.*; Tajudin, S. M.*; Aziz, M. Z. A.*; Furuta, Takuya
Radiological Physics and Technology, 16(1), p.109 - 117, 2023/03
The spatial distributions of photon dose rates in a brachytherapy room with an Iridium-192 were simulated by using the particle and heavy ion transport code system (PHITS). A geometry of the brachytherapy room with concrete walls and a sliding lead door was reproduced by tracing the existing room in Advanced Medical and Dental Institute at the Universiti Sains Malaysia in Penang. The simulation results were confirmed by comparing to the measured results using a thermoluminescent dosimeter. The simulation study suggested that an additional layer of 3-mm thick lead at the side wall of the entrance will efficiently reduce the dose outside the entrance due to the photons leaked from the edge of the entrance. Simulation with replacing the source with Cobalt-60 was also conducted and revealed the dose level outside the room was too high compared to regulatory value in the current room configuration.
Furuta, Takuya; Koba, Yusuke*; Hashimoto, Shintaro; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Ishikawa, Akihisa*; Sato, Tatsuhiko
Physics in Medicine & Biology, 67(14), p.145002_1 - 145002_15, 2022/07
Times Cited Count：7 Percentile：61.41(Engineering, Biomedical)Carbon ion radiotherapy has an advantage over conventional radiotherapy such that its superior dose concentration on the tumor helps to reduce unwanted dose to surrounding normal tissues. Nevertheless, a little dose to normal tissues, which is a potential risk of secondary cancer, is still unavoidable. The Monte Carlo simulation is a good candidate for the tool to assess secondary cancer risk, including the contributions of secondary particles produced by nuclear reactions. We therefore developed a new dose reconstruction system implementing PHITS as the engine. In this system, the PHITS input is automatically created from the DICOM data sets recorded in the treatment planning. The developed system was validated by comparing to experimental dose distribution in water and treatment plan on an anthropomorphic phantom. This system will be used for retrospective studies using the patient data in National Institute for Quantum and Science and Technology.
Katsuyama, Jinya; Yamaguchi, Yoshihito; Nemoto, Yoshiyuki; Furuta, Takuya; Kaji, Yoshiyuki
Proceedings of ASME 2022 Pressure Vessels and Piping Conference (PVP 2022) (Internet), 9 Pages, 2022/07
Furuta, Takuya
Igaku Butsuri, 41(4), P. 194, 2021/12
Number of medical uses of Particle and Heavy Ion Transport code System (PHITS) has been increased due to the recent high demands of medical use of radiations. The summary of such research works was described in the review article on medical application of Particle and Heavy Ion Transport code System PHITS published in Radiological Physics and Technology in 2021. There was a request from the editorial board of Japan Society of Medical Physics (JSMP) for writing an introductory article of this article in their internal journal. The research works on medical applications described in the review article, useful functions for medical application in PHITS, and newly opened user forum of PHITS have been introduced.
Tominaga, Masahide*; Nagayasu, Yukari*; Sasaki, Motoharu*; Furuta, Takuya; Hayashi, Hiroaki*; Oita, Masataka*; Nishiyama, Yuichi*; Haga, Akihiro*
Radiological Physics and Technology, 14(4), p.381 - 389, 2021/12
Due to recent advance of diagnostic radiology, the increase of diagnostic radiation exposure to patient becomes problem. Diagnostic Reference Levels has been released to optimized the radiation exposure to patients in Japan recently. The evaluation of entrance surface dose (ESD) is recommended to assess the dose level for general X-ray examination. The ESD can be easily evaluated by multiplying the backscatter factor of the patient body on the free-in-air air kerma. The air kerma free-in-air value used to estimate ESD may contain X-rays scattered from obstacles located at the time of measurement, which may induce non-minor error in assessments. We therefore studied the influence of scattered X-rays on air kerma measurement under various environments (distances, field sizes, and materials). It was found that the dependence on the X-ray energy and field size was different for different materials. The X-ray contamination can be ignored for all the materials when the distance to the scatterer exceeds 35 cm.
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
Times Cited Count：4 Percentile：25.72(Biology)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.
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.
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：17 Percentile：80.36(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.
Satoh, Daiki; Nakayama, Hiromasa; Furuta, Takuya; Yoshihiro, Tamotsu*; Sakamoto, Kensaku
PLOS ONE (Internet), 16(1), p.e0245932_1 - e0245932_26, 2021/01
Times Cited Count：2 Percentile：21.34(Multidisciplinary Sciences)In this study, we developed a simulation code named SIBYL, which estimates external gamma-ray doses at ground level from radionuclides distributed nonuniformly in atmosphere and on ground. SIBYL can combine with the local-scale atmospheric dispersion model LOHDIM-LES, and calculate the dose distributions according to the map of the activity concentrations simulated by LOHDIM-LES. To apply the SIBYL code to emergency responses of nuclear accidents, the time-consuming three-dimensional radiation transport simulations were performed in advance using the general-purpose Monte Carlo code PHITS, and then the results were compiled to the database for the SIBYL's dose calculations. Moreover, SIBYL can consider the dose attenuation by obstacles and the changes of terrain elevations. To examine the accuracy of SIBYL, typical five cases including 
Kr emission from a ventilation shaft and 
Cs dispersion inside urban area were investigated. The results of SIBYL agreed within 10% with those of PHITS at the most of target locations. Furthermore, the calculation speed was approximately 100 times faster than that of PHITS.
Toigawa, Tomohiro; Tsubata, Yasuhiro; Kai, Takeshi; Furuta, Takuya; Kumagai, Yuta; Matsumura, Tatsuro
Solvent Extraction and Ion Exchange, 39(1), p.74 - 89, 2021/00
Times Cited Count：2 Percentile：7.60(Chemistry, Multidisciplinary)Absorbed-dose estimation is essential for evaluation of the radiation feasibility of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha ray depends upon the emulsion structure, and that from beta and gamma ray depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process.
