量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Purpose:
A magnetic field longitudinal to an ion beam will potentially affect the biological effectiveness of the radiation. The purpose of this study is to experimentally verify the significance of such effects.
Methods and Materials:
Human cancer and normal cell lines were exposed to low (12 keV/μm) and high (50 keV/μm) linear energy transfer (LET) carbon-ion beams under the longitudinal magnetic fields of B// = 0, 0.1, 0.2, 0.3, or 0.6 T generated by a solenoid magnet. The effects of the magnetic fields on the biological effectiveness were evaluated by clonogenic cell survival. Doses that would result in a survival fraction of 10% (D10s) were determined for each cell line and magnetic field.
Results:
For cancer cells exposed to the low (high)-LET beams, D10 decreased from 5.2 (3.1) Gy at 0 T to 4.3 (2.4) Gy at 0.1 T, while no further decrease in D10 was observed for higher magnetic fields. For normal cells, decreases in D10 of comparable magnitudes were observed by applying the magnetic fields.
Conclusions:
Significant decreases in D10, i.e., significant enhancements of the biological effectiveness, were observed in both cancer and normal cells by applying longitudinal magnetic fields of B// ≥ 0.1 T. These effects were enhanced with LET. Further studies are required to figure out the mechanism underlying the observed results.
Enhancement of biological effectiveness of carbon-ion beams by applying a longitudinal magnetic field
