Hawkins R B
Department of Radiation Oncology, Ochsner Clinic, New Orleans, Louisiana 70121.
Radiat Res. 1994 Dec;140(3):366-74.
A theory is presented that provides an explanation for the observed features of the survival of cultured cells after exposure to densely ionizing high-linear energy transfer (LET) radiation. It starts from a phenomenological postulate based on the linear-quadratic form of cell survival observed for low-LET radiation and uses principles of statistics and fluctuation theory to demonstrate that the effect of varying LET on cell survival can be attributed to random variation of dose to small volumes contained within the nucleus. A simple relation is presented for surviving fraction of cells after exposure to radiation of varying LET that depends on the alpha and beta parameters for the same cells in the limit of low-LET radiation. This relation implies that the value of beta is independent of LET. Agreement of the theory with selected observations of cell survival from the literature is demonstrated. A relation is presented that gives relative biological effectiveness (RBE) as a function of the alpha and beta parameters for low-LET radiation. Measurements from microdosimetry are used to estimate the size of the subnuclear volume to which the fluctuation pertains.
本文提出了一种理论，用于解释培养细胞在暴露于高传能线密度（LET）的密集电离辐射后存活的观测特征。该理论始于一个基于低LET辐射下细胞存活的线性二次形式的现象学假设，并运用统计学原理和涨落理论来证明，LET变化对细胞存活的影响可归因于细胞核内小体积区域剂量的随机变化。文中给出了一个简单的关系式，用于描述细胞在不同LET辐射下的存活分数，该关系式取决于低LET辐射极限下相同细胞的α和β参数。此关系式意味着β值与LET无关。文中证明了该理论与文献中细胞存活的部分观测结果相符。还给出了一个关系式，将相对生物效能（RBE）表示为低LET辐射的α和β参数的函数。利用微剂量学测量来估计涨落所涉及的亚核体积大小。
