A method for computing the decision level for samples containing radioactivity in the presence of background.
A method for computing the decision level for samples containing radioactivity in the presence of background.
复制标题
一种在存在背景的情况下计算含有放射性的样品的决策水平的方法。
作者：
T. Borak;T. Kirchner
通常需要确定样品是否含有超过本底的放射性。最常见的程序是确定性方法，将每个样品的结果与临界水平Lc进行比较。最初，Lc是根据每个样品与已知不含过量放射性的空白或对照配对的情况得出的。然而，大多数分析实验室并不处理每个样品的空白。另一种方法使用测量的集合来计算Lc以形成“明确定义的”背景。本文提出了一种确定决策水平L δ的方法，它包括背景均值和方差的不确定性，以及这些不确定性如何联合收割机在估计背景分布的尾部时形成不确定性。对于给定的I型误差，L δ的值大于Lc。当背景的真实分布为正态分布或对数正态分布时，可以应用该方法。该过程不限于计数统计，并且对于识别任何类型的过量污染是有效的，只要未知样品与背景样品相同地处理。
It is often necessary to make a decision whether or not a sample contains radioactivity in excess of background. The most common procedure is a deterministic approach that compares the result from each sample against a critical level, Lc. Originally Lc was derived from the case where each sample is paired with a blank or control that is known not to contain excess radioactivity. However, most analytic laboratories do not process a blank with each and every sample. Another approach computes Lc using a collection of measurements to form a "well defined" background. This paper presents a method for determining a decision level, L delta, that includes the uncertainties in both the mean and variance of background and how these combine to form uncertainties in estimating the tails of the background distribution. The values of L delta are greater than Lc for a given Type I error. It can be applied whenever the true distribution of background is either normal or log normal. The process is not restricted to counting statistics and is valid for identifying excess contamination of any type providing that unknown samples are processed identically to background samples.