ECAP-Erlangen Centre for Astroparticle Physics, University of Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany.
Med Phys. 2011 Jul;38(7):4133-40. doi: 10.1118/1.3592935.
Grating-based x-ray phase-contrast imaging is a fast developing new modality not only for medical imaging, but as well for other fields such as material sciences. While these many possible applications arise, the knowledge of the noise behavior is essential.
In this work, the authors used a least squares fitting algorithm to calculate the noise behavior of the three quantities absorption, differential phase, and dark-field image. Further, the calculated error formula of the differential phase image was verified by measurements. Therefore, a Talbot interferometer was setup, using a microfocus x-ray tube as source and a Timepix detector for photon counting. Additionally, simulations regarding this topic were performed.
It turned out that the variance of the reconstructed phase is only dependent of the total number of photons used to generate the phase image and the visibility of the experimental setup. These results could be evaluated in measurements as well as in simulations. Furthermore, the correlation between absorption and dark-field image was calculated.
These results provide the understanding of the noise characteristics of grating-based phase-contrast imaging and will help to improve image quality.
基于光栅的 X 射线相衬成像是一种快速发展的新模态，不仅可用于医学成像，还可用于材料科学等其他领域。随着这些可能的应用的出现，对噪声特性的了解是必不可少的。
在这项工作中，作者使用最小二乘法拟合算法来计算吸收、差分相位和暗场图像这三个量的噪声特性。此外，通过测量验证了差分相位图像的计算误差公式。因此，建立了一个泰伯干涉仪，使用微焦点 X 射线管作为光源和光子计数的 Timepix 探测器。此外，还针对这一主题进行了模拟。
结果表明，重建相位的方差仅取决于用于生成相位图像的总光子数和实验装置的可见度。这些结果可以在测量和模拟中进行评估。此外，还计算了吸收和暗场图像之间的相关性。
这些结果提供了对基于光栅的相衬成像噪声特性的理解，并将有助于提高图像质量。
