arXiv:2503.23148physics.opticseess.IV2025-03

通过多谐波与相位步长校正,显著减少X射线光栅干涉成像中的伪影。

Reducing Artifacts in Grating Interferometry Using Multiple Harmonics and Phase Step Corrections

  • 利用多谐波和直接相对相位拟合,提升条纹图案匹配精度。
  • 校正相位步长位置后,传输、差相及暗场图像中伪影明显减少。
  • 适用于肺部、微球等生物与材料样本的高精度成像,适合医学与工业检测领域。

X射线干涉成像是具有广泛临床应用前景的新成像技术,可用于肺部、乳腺成像以及增材制造和孔隙度分析等无损检测。光栅干涉仪通过衍射光栅生成周期性干涉条纹,测量样品对条纹的扰动,分别获得吸收、折射和小角度散射图像(即透射图、差相图和暗场图)。当假设条纹为理想正弦波且相位步长均匀时,会引入特有的图像伪影。光栅位置误差与多谐波条纹共同导致残余振荡和相位折叠伪影。本文提出一种图像恢复算法,结合多谐波建模、直接相对相位拟合及相位步长校正,有效抑制伪影。直接相对相位拟合消除相位折叠问题;修正相位步长并引入额外谐波,可去除透射图、差相图与暗场图中的光栅残余伪影。通过在聚甲基丙烯酸甲酯微球、离体甲醛固定小鼠肺及多孔氧化铝样品上的实验验证,该方法显著改善条纹拟合效果,大幅降低伪影,提升成像质量。

原文摘要 · Abstract (English)

X-ray interferometry is an emerging imaging modality with a wide variety of potential clinical applications, including lung and breast imaging, as well as in non-destructive testing, such as additive manufacturing and porosimetry. A grating interferometer uses a diffraction grating to produce a periodic interference pattern and measures how a patient or sample perturbs the pattern, producing three unique images that highlight X-ray absorption, refraction, and small angle scattering, known as the transmission, differential-phase, and dark-field images, respectively. Image artifacts that are unique to X-ray interferometry are introduced when assuming the fringe pattern is perfectly sinusoidal and the phase steps are evenly spaced. Inaccuracies in grating position, coupled with multi-harmonic fringes, lead to remnant oscillations and phase wraparound artifacts. We have developed an image recovery algorithm that uses additional harmonics, direct relative phase fitting, and phase step corrections to prevent them. The direct relative phase fitting removes the phase wraparound artifact. Correcting the phase step positions and introducing the additional harmonic removes the grating remnant artifact present in the transmission, differential-phase, and dark-field images. By modifying existing algorithms, the fit to the fringe pattern is greatly improved and artifacts are minimized, as we demonstrate with the imaging of several samples, including PMMA microspheres, ex vivo formalin fixed mouse lungs, and porous alumina.

X射线成像光栅干涉伪影消除医学成像

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