Braselmann Herbert, Michna Agata, Heß Julia, Unger Kristian
Research Unit Radiation Cytogenetics, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, Neuherberg, Germany.
Clinical Cooperation Group 'Personalized Radiotherapy of Head and Neck Cancer', Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, Neuherberg, Germany.
Radiat Oncol. 2015 Nov 4;10:223. doi: 10.1186/s13014-015-0529-y.
Colony formation assay is the gold standard to determine cell reproductive death after treatment with ionizing radiation, applied for different cell lines or in combination with other treatment modalities. Associated linear-quadratic cell survival curves can be calculated with different methods. For easy code exchange and methodological standardisation among collaborating laboratories a software package CFAssay for R (R Core Team, R: A Language and Environment for Statistical Computing, 2014) was established to perform thorough statistical analysis of linear-quadratic cell survival curves after treatment with ionizing radiation and of two-way designs of experiments with chemical treatments only.
CFAssay offers maximum likelihood and related methods by default and the least squares or weighted least squares method can be optionally chosen. A test for comparision of cell survival curves and an ANOVA test for experimental two-way designs are provided.
For the two presented examples estimated parameters do not differ much between maximum-likelihood and least squares. However the dispersion parameter of the quasi-likelihood method is much more sensitive for statistical variation in the data than the multiple R (2) coefficient of determination from the least squares method.
The dispersion parameter for goodness of fit and different plot functions in CFAssay help to evaluate experimental data quality. As open source software interlaboratory code sharing between users is facilitated.
The package is available at http://www.bioconductor.org/packages/release/bioc/html/CFAssay.html .
集落形成试验是确定电离辐射处理后细胞繁殖性死亡的金标准，适用于不同细胞系或与其他治疗方式联合使用。相关的线性二次细胞存活曲线可以用不同方法计算。为便于合作实验室之间的代码交换和方法标准化，开发了一个用于R的软件包CFAssay（R核心团队，《R：用于统计计算的语言和环境》，2014年），以对电离辐射处理后的线性二次细胞存活曲线以及仅采用化学处理的双向实验设计进行全面统计分析。
CFAssay默认提供最大似然法及相关方法，也可选择最小二乘法或加权最小二乘法。提供了细胞存活曲线比较检验和实验双向设计的方差分析检验。
对于所展示的两个例子，最大似然法和最小二乘法估计的参数差异不大。然而，拟似然法的离散参数比最小二乘法的多重决定系数R²对数据中的统计变异更敏感。
CFAssay中用于拟合优度的离散参数和不同的绘图函数有助于评估实验数据质量。作为开源软件，便于用户之间进行实验室间代码共享。
该软件包可在http://www.bioconductor.org/packages/release/bioc/html/CFAssay.html获取。
