X射线光栅相位衬度成像技术中背景扣除方法的比较(英文)

Background correction methods in X-ray phase-contrast imaging with Talbot-Lau interferometer:a comparative study

在基于Talbot-Lau干涉仪的X射线相位衬度成像技术中,为了得到纯样品的相位信息,背景扣除是一个必不可少的步骤。本研究对相位衬度成像中的背景扣除方法进行了研究,尤其是针对目前经常使用的一种背景扣除方法,提出了一种新的相位解缠绕方案,即[arg(S)-arg(B)]cyclic shift算法,该方案的核心思想是对原始图像序列进行循环移位操作,从而达到改变相位的目的。实验结果和数值分析表明,该相位解缠绕方案可以完全消除上述背景扣除方法中的相位缠绕现象。同时,基于这种方案,相位的有效测量范围可以根据情况灵活调节,如调为(-π+3,π+3],而目前常用背景扣除方法的相位测量范围都是固定在(-π,π]。

In X-ray phase-contrast imaging with Talbot-Lau interferometer, a background correction process has to be performed to obtain the pure signal of the sample. In this study, we tested the performances of different background correction strategies and proposed a novel background correction method,[arg（S）-arg（B）]cyclic shift, in which the initial phase of each pixel is changed by a cyclic shift operation on the raw image data from phase step-scan. Both experimental results and numerical analysis showed that the improved method could successfully realize background correction without error. In addition, the effective phase measuring range of this method allowed flexible tuning within（-π＋3, π＋3], as compared with the fixed effective measuring range of（-π, π]in the conventional methods.