Van Nieuwenhove Vincent, De Beenhouwer Jan, De Carlo Francesco, Mancini Lucia, Marone Federica, Sijbers Jan
Opt Express. 2015 Oct 19;23(21):27975-89. doi: 10.1364/OE.23.027975.
In X-ray imaging, it is common practice to normalize the acquired projection data with averaged flat fields taken prior to the scan. Unfortunately, due to source instabilities, vibrating beamline components such as the monochromator, time varying detector properties, or other confounding factors, flat fields are often far from stationary, resulting in significant systematic errors in intensity normalization. In this work, a simple and efficient method is proposed to account for dynamically varying flat fields. Through principal component analysis of a set of flat fields, eigen flat fields are computed. A linear combination of the most important eigen flat fields is then used to individually normalize each X-ray projection. Experiments show that the proposed dynamic flat field correction leads to a substantial reduction of systematic errors in projection intensity normalization compared to conventional flat field correction.
在X射线成像中，通常的做法是用扫描前采集的平均平场对获取的投影数据进行归一化处理。不幸的是，由于光源不稳定、诸如单色仪等振动的束线组件、随时间变化的探测器特性或其他混杂因素，平场往往远非稳定不变，这导致强度归一化中出现显著的系统误差。在这项工作中，提出了一种简单有效的方法来处理动态变化的平场。通过对一组平场进行主成分分析，计算出特征平场。然后，使用最重要的特征平场的线性组合来分别对每个X射线投影进行归一化。实验表明，与传统的平场校正相比，所提出的动态平场校正可大幅减少投影强度归一化中的系统误差。
