Wieczorek M, Schaff F, Pfeiffer F, Lasser T
Computer Aided Medical Procedures, Technische Universität München, 85748 Garching, Germany.
Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
Phys Rev Lett. 2016 Oct 7;117(15):158101. doi: 10.1103/PhysRevLett.117.158101. Epub 2016 Oct 5.
The x-ray dark-field signal measured in grating interferometers is anisotropic, depending on both the beam direction and the grating orientation with respect to the sample. We present a novel general closed-form, continuous forward model of the anisotropic dark-field signal. Furthermore, we derive a discretization using spherical harmonics, leading to a large-scale linear inverse problem. We present first experimental results of a wooden sample, demonstrating marked advantages over previous results, in particular, the resolution of multiple scattering directions in one volume element.
在光栅干涉仪中测量的X射线暗场信号是各向异性的，这取决于光束方向以及光栅相对于样品的取向。我们提出了一种新颖的通用封闭形式的各向异性暗场信号连续正向模型。此外，我们推导了一种使用球谐函数的离散化方法，从而得到一个大规模线性逆问题。我们展示了对一个木制样品的首次实验结果，证明了相对于先前结果具有显著优势，特别是在一个体积元中分辨多个散射方向的能力。
