量子噪声与源模糊对X射线散斑成像中暗场信号检索的影响
Effects of Quantum Noise and Source Blurring on Dark-Field Signal Retrieval in X-ray Speckle-Based Imaging
AI总结：
本文研究量子噪声与源模糊对X射线散斑成像暗场信号检索的影响，评估LCS和XST-XSVT两种框架的鲁棒性，明确其在光子匮乏和源模糊下的性能差异，为相关系统建立操作边界并指导算法优化。
AI中文摘要：
X射线散斑基暗场成像对亚像素结构特征具有高灵敏度，但其在临床与临床前环境中的定量可靠性受限于低光子通量和有限焦斑尺寸。然而，硬件诱导的噪声和源模糊如何通过检索算法传播并降低信号完整性尚未被完全理解。本文中，我们在两种数学上不同的框架下，基于信号线性度、灵敏度和偏差量化算法鲁棒性，对光子匮乏和源模糊情况进行系统评估：基于微分的固有跟踪（低相干系统，LCS）和逐块显式跟踪（X射线散斑跟踪-散斑矢量跟踪，XST-XSVT）。实验结果表明，输入散斑图案的失真会根据算法架构以根本不同的方式通过检索算法传播。例如，在我们的装置下，严重光子匮乏时，LCS中的微分噪声放大会导致其暗场信号线性度和灵敏度急剧下降，同时基线偏差大幅升高；相比之下，XST-XSVT通过逐块方差计算固有抑制随机噪声，限制了灵敏度损失并保持稳定基线。类似地，在模糊受限条件下，源模糊会冲刷散斑图案，直接降低LCS和XST-XSVT的暗场灵敏度。该表征为低功率和低相干X射线系统建立了操作边界，指导算法选择和框架优化，以实现临床前和临床应用中的定量暗场成像。
英文摘要：
X-ray speckle-based dark-field imaging offers high sensitivity to sub-pixel structural features, yet its quantitative reliability in clinical and preclinical settings remains constrained by low photon flux and finite focal spot sizes. However, how hardware-induced noise and source blurring propagate through retrieval algorithms to degrade signal integrity is not fully understood. Here, we systematically evaluate algorithm robustness quantified by signal linearity, sensitivity, and bias under photon starvation and source blurring across two mathematically distinct frameworks: differential-based intrinsic tracking (Low-Coherence System, LCS) and patch-wise explicit tracking (X-ray Speckle-Tracking Speckle-Vector-Tracking, XST-XSVT). Our experimental results demonstrate that input speckle pattern distortions propagate through retrieval algorithms in fundamentally different ways depending on algorithm architecture. As an example, using our setup, under severe photon starvation, derivative noise amplification in LCS causes its dark-field signal linearity and sensitivity to drop precipitously, while sharply elevating baseline bias. In contrast, XST-XSVT restricts these losses for sensitivity while maintaining a stable baseline, as its patch-wise variance calculation inherently suppresses stochastic noise. Similarly, under blur-limited conditions , source blurring washes out the speckle pattern, directly reducing dark-field sensitivity for both LCS and XST-XSVT. This characterization establishes operational boundaries for low-power and low-coherence X-ray systems, guiding algorithm selection and framework optimization to realize quantitative dark-field imaging in preclinical and clinical applications.
