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 and Radiological Science and Technology.
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Purpose: Radiotherapy using charged and/or high-linear energy transfer (LET) particles has a long history, starting with proton beams up to now carbon-ions. Radiation quality of particle beams is different from conventional photons, and
therefore the biological effects of high-LET irradiation have attracted scientific interests of many scientists in basic and clinical fields. A brief history of particle radiotherapy in the past half-century is followed by the reviewed biological effectiveness of high-LET charged particles.
Results: The latter includes 54 papers presenting 506 RBE (relative biological effectiveness) values for carbon ions and a total of 290 RBE values for other ions identified from 48 papers. By setting a selection window of LET up to 100 keV/mm, we
fitted a linear regression line to an LET-RBE relation. The resulting slope of the regression line had a dimension of mm/keV, and showed different steepness for different cells/tissues and endpoints as well. The steepest regression was found for
chromosome aberration of human malignant melanoma while the shallowest was for apoptosis of rodent cells/tissue. Both tumour and normal tissue showed relatively shallower slopes than colony formation.
Conclusions: In general, there is a large variation of slope values, but the majority (25 out of 29 values) of data was smaller than 0.05 mm/keV.
Biological characteristics of carbon-ion therapy
