Ando Koichi, Kase Yuki
Medicine and Biology Division, Gunma University Heavy Ion Medical Center, Showa-machi 3-39-22, Maebashi-shi, Gunma, Japan.
Int J Radiat Biol. 2009 Sep;85(9):715-28. doi: 10.1080/09553000903072470.
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.
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/microm, we fitted a linear regression line to an LET-RBE relation. The resulting slope of the regression line had a dimension of microm/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.
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 microm/keV.
使用带电和/或高线性能量传递（LET）粒子进行放射治疗有着悠久的历史，从质子束开始，直至如今的碳离子束。粒子束的辐射质量不同于传统光子，因此高LET辐射的生物学效应吸引了基础和临床领域众多科学家的关注。在回顾高LET带电粒子的生物学有效性之前，先简要介绍一下过去半个世纪粒子放射治疗的历史。
后者包括54篇论文，给出了碳离子的506个相对生物效应（RBE）值，以及从48篇论文中确定的其他离子的总共290个RBE值。通过设置LET高达100 keV/μm的选择窗口，我们对LET-RBE关系拟合了一条线性回归线。回归线的斜率具有μm/keV的量纲，并且对于不同的细胞/组织和终点也显示出不同的陡度。在人类恶性黑色素瘤的染色体畸变中发现最陡的回归线，而在啮齿动物细胞/组织的凋亡中则是最浅的。肿瘤组织和正常组织的斜率都比集落形成相对更浅。
一般来说，斜率值有很大差异，但大多数（29个值中的25个）数据小于0.05μm/keV。
