ANALYSIS OF CELL-SURVIVAL FRACTIONS FOR HEAVY-ION IRRADIATIONS BASED ON MICRODOSIMETRIC KINETIC MODEL IMPLEMENTED IN THE PARTICLE AND HEAVY ION TRANSPORT CODE SYSTEM
ANALYSIS OF CELL-SURVIVAL FRACTIONS FOR HEAVY-ION IRRADIATIONS BASED ON MICRODOSIMETRIC KINETIC MODEL IMPLEMENTED IN THE PARTICLE AND HEAVY ION TRANSPORT CODE SYSTEM
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DOI：
10.1093/rpd/ncq484
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发表时间：
2011-02-01
影响因子：
1
通讯作者：
Niita, K.
中科院分区：
文献类型：
--
作者：
Sato, T.;Watanabe, R.;Niita, K.
有人认为，线性能量传递（LET）可能不是表示重离子辐照细胞杀伤的相对生物学效应（RBE）的理想指标，因为在来自细胞存活分数数据的LET和RBE之间的关系中已经清楚地观察到离子种类依赖性。先前测量的存活分数的四个细胞系照射的各种离子种类，采用饱和校正的剂量平均线性能量，y*，而不是LET的RBE的指数，因此重新分析。在分析中，存活分数的初始斜率，即线性二次模型中所谓的α参数，被绘制为y* 的函数，y * 是通过粒子和重离子传输代码系统中实施的微剂量动力学（MK）模型计算的。从分析中发现，在a与LET之间的关系中观察到的离子-物种依赖性从a与y* 之间的关系中消失，并且它们的关系可以由MK模型导出的简单方程很好地再现。这些结果清楚地表明y* 用于估计重离子辐照的细胞杀伤的RBE的适合性，这在带电粒子治疗的治疗计划中是非常重要的。
It is considered that the linear energy transfer (LET) may not be the ideal index for expressing the relative biological effectiveness (RBE) of cell killing for heavy-ion irradiation, as the ion-species dependencies have clearly been observed in the relation between LET and RBE derived from cell-survival fraction data. The previously measured survival fractions of four cell lines irradiated by various ion species, employing the saturation-corrected dose-mean lineal energy, y*, instead of LET as the index of the RBE were therefore re-analysed. In the analysis, the initial slopes of the survival fractions, the so-called alpha-parameter in the linear-quadratic model, were plotted as a function of y*, which was calculated by the microdosimetric kinetic (MK) model implemented in the Particle and Heavy Ion Transport code System. It was found from the analysis that the ion-species dependencies observed in the relations between a and LET disappeared from those between a and y*, and their relations can be well reproduced by a simple equation derived from the MK model. These results clearly indicate the suitability of y* to be used in the estimation of the RBE of cell killing for heavy-ion irradiations, which is of great importance in the treatment planning of charged-particle therapy.