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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.
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：3 Percentile：44.25(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.
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：3 Percentile：25.1(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.
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Kobayashi, Yasuhiko
Isotope News, (741), p.21 - 25, 2016/01
Our article published on the International Journal of Radiation Biology (2015) was reviewed. We investigated the dependence of the bystander cell-killing effect on radiation dose and quality, and related molecular mechanisms. Human fibroblasts were irradiated with 
-rays or carbon ions and co-cultured with non-irradiated cells. Survival rates of non-irradiated cells decreased and nitrite concentrations in co-culture medium increased with dose. Their dose responses were similar between -rays and carbon ions. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of non-irradiated cells. Negative relationships were observed between survival rates and nitrite concentrations. From these results, it was concluded that the bystander cell-killing effect mediated by NO radicals depends on irradiation doses, but not on radiation quality. NO radical production appears to be an important determinant of bystander effects.
Yamaguchi, Mitsutaka; Nagao, Yuto; Kawachi, Naoki; Sato, Takahiro; Fujimaki, Shu; Kamiya, Tomihiro; Torikai, Kota*; Shimada, Hirofumi*; Sugai, Hiroyuki*; Sakai, Makoto*; et al.
International Journal of PIXE, 26(1&2), p.61 - 72, 2016/00
no abstracts in English
Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Kobayashi, Yasuhiko; Kanai, Tatsuaki*
no journal, ,
The purpose of this research is to analyze carbon-ion induced bystander effects via medium, and is to understand a characteristic phenomenon between different type cells. In this research, human lung normal fibroblasts WI-38 and human lung cancer cells H1299/wt
were used. Cells were irradiated with carbon-ion broad beams (LET=108 keV/
m, Dose=0.13, 0.5 Gy), then survival rates of bystander cells after 6- or 24-hours co-culture with irradiated cells were measured using colony formation assay. When dose was changed, we found that bystander responses are also different between irradiated WI-38 and non-irradiated H1299/wt.
Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Kanai, Tatsuaki*; Nakano, Takashi*; Kobayashi, Yasuhiko
no journal, ,
In this study, human lung normal fibroblasts WI-38 and human lung cancer cells H1299/wt were used. Cells were irradiated with carbon-ion broad beams, then survival rates of bystander cells after co-culture with irradiated cells were measured using colony assay. The survival rates of non-irradiated bystander cancer cells co-cultured with 0.13 Gy irradiated normal cells increased after 6-hours co-culture. On the other hand, the bystander cells co-cultured with 0.5 Gy irradiated normal cells showed decreased survival rates. These results indicated that the bystander responses of the cancer cells changes according to the irradiation dose on the normal cells. In addition, the survival rates of bystander cancer cells showed a tendency to increase by the addition of Carboxy-PTIO to the co-culture medium, when co-cultured with 0.5 Gy irradiated normal cells. From these results, reduction of survival rates is likely to be caused by NO radical as a mediator in bystander effects.
Yamaguchi, Mitsutaka; Nagao, Yuto; Sugai, Hiroyuki*; Sakai, Makoto*; Kawachi, Naoki; Sato, Takahiro; Kamiya, Tomihiro; Fujimaki, Shu; Arakawa, Kazuo*; Narumi, Kazumasa
no journal, ,
no abstracts in English
Ishikawa, Akihisa*; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Hashimoto, Shintaro; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Sato, Tatsuhiko
no journal, ,
There found to be a relationship between the dose-averaged linear energy transfer LETd and local tumor control in carbon-ion radiotherapy (CIRT). However, only physical dose and biological dose are registered in the past treatment records of CIRT in QST hospital and LETd can not be deduced directly. There is a method to estimate LETd based on RBE-LETd-fitted function but some problems such as non-singularity at the end point of carbon ions are known. On the other hand, we propose a method to reproduce the CIRT by reconstructing the beam transport geometry based on the treatment planning data and conduct Monte Carlo simulation. The LETd can be also computed directly. We therefore compared LETd obtained by Monte Carlo simulation with estimated LETd using the treatment planning data. We found that underestimation around the end point of carbon ions but the influence was local and thus the LETd estimates are valid for the purpose computing in organ scale.
