Localization accuracy in single molecule microscopy using electron-multiplying charge-coupled device cameras.
Localization accuracy in single molecule microscopy using electron-multiplying charge-coupled device cameras.
复制标题
使用电子倍增电荷耦合器件相机的单分子显微镜定位精度。
DOI：
10.1117/12.908951
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Ober,RaimundJ
中科院分区：
文献类型：
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作者：
Chao,Jerry;Ward,ESally;Ober,RaimundJ
电子倍增电荷耦合器件（EMCCD）是一种在极弱光条件下成像的流行技术。它已经被广泛使用，例如，在单分子显微镜实验中，很少有光子可以从感兴趣的单个分子中检测到。尽管它在微光显微镜中发挥着重要的作用，然而，在确定如何准确地从它产生的图像中估计感兴趣的参数（例如，单个分子的位置）方面做得很少。在这里，我们发展了计算Fisher信息矩阵的理论，从而建立了基于精度下限的Cramer-Rao，用于估计EMCCD图像的参数。EMCCD的工作原理是放大微弱的信号，否则就会像传统的电荷耦合器件（CCD）那样被探测器的读出噪声淹没。信号放大是一个随机的电子倍增过程，本文将其建模为一个几何倍增的分支过程。在发展我们的理论时，我们还引入了一个“噪声系数”，它可以通过标量量来比较不同数据模型的费雪信息。重要的是，该系数允许根据信号电平等因素选择最佳检测器（例如，EMCCD或CCD），而不管手头的具体估计问题。我们将我们的理论应用于单个分子的定位问题，并将定位精度的计算极限与从单个分子的模拟图像中获得的最大似然定位估计的标准偏差进行比较。
The electron-multiplying charge-coupled device (EMCCD) is a popular technology for imaging under extremely low light conditions. It has become widely used, for example, in single molecule microscopy experiments where few photons can be detected from the individual molecules of interest. Despite its important role in low light microscopy, however, little has been done in the way of determining how accurately parameters of interest (e.g., location of a single molecule) can be estimated from an image that it produces. Here, we develop the theory for calculating the Fisher information matrix, and hence the Cramer-Rao lower bound-based limit of the accuracy, for estimating parameters from an EMCCD image. An EMCCD operates by amplifying a weak signal that would otherwise be drowned out by the detector's readout noise as in the case of a conventional charge-coupled device (CCD). The signal amplification is a stochastic electron multiplication process, and is modeled here as a geometrically multiplied branching process. In developing our theory, we also introduce a "noise coefficient" which enables the comparison of the Fisher information of different data models via a scalar quantity. This coefficient importantly allows the selection of the best detector (e.g., EMCCD or CCD), based on factors such as the signal level, and regardless of the specific estimation problem at hand. We apply our theory to the problem of localizing a single molecule, and compare the calculated limits of the localization accuracy with the standard deviations of maximum likelihood location estimates obtained from simulated images of a single molecule.