2019 Fiscal Year Final Research Report
Dose calculation algorithm for charged-particle beams passing through materials with microheterogeneity
| Project/Area Number |
17K09074
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Medical Physics and Radiological Technology
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| Research Institution | National Institutes for Quantum and Radiological Science and Technology |
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Principal Investigator |
Inaniwa Taku 国立研究開発法人量子科学技術研究開発機構, 放射線医学総合研究所 物理工学部, グループリーダー(定常) (10446536)
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| Co-Investigator(Kenkyū-buntansha) |
兼松 伸幸 国立研究開発法人量子科学技術研究開発機構, 放射線医学総合研究所 物理工学部, 次長(定常) (10221889)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 粒子線治療 / 線量計算 / 不均質物質 / 治療計画 |
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| Outline of Final Research Achievements |
The materials with microheterogeneity such as lung tissues and patient immobilization devices will distort the dose distribution of charged-particle beams. The purpose of this study is to develop a dose calculation algorithm to deal with this problem. The heterogeneous material was assumed to be composed of small voxels filed with water or air. Then, variance of the water-equivalent thickness of the material could be estimated based on a binominal theorem. Dose distribution of a beam passing through the material was calculated by convoluting pristine Bragg peaks of charged-particle beams according to the variance. This dose-calculation algorithm was integrated into the treatment planning system of charged-particle therapy, and was validated through beam experiments. Finally, the effects of an immobilization device on patient dose distribution were investigated for a clinical case treated with carbon-ion beams.
Parts of this study have been published in PMB.
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| Free Research Field |
医学物理
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| Academic Significance and Societal Importance of the Research Achievements |
粒子線が固定具や肺組織などの微細な構造をもつ不均質物質を通過すると、粒子線の線量分布が乱れ、患者内の線量分布に大きな誤差が生じる可能性がある。本研究では、不均質物質による粒子線線量分布の変化を記述する数学アルゴリズムを開発し、これを粒子線治療計画システムに実装した。これにより、不均質物質が患者内の線量分布に与える影響を定量的に評価することが可能になった。また、この計算誤差を補正することで、これまで以上に高精度な粒子線治療が提供可能になった。
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