Rosich Diego, Chevalier Margarita, Alieva Tatiana
Physics Institute of Cantabria (IFCA-CSIC-UC), Av. de los Castros s/n, 39005 Santander, Spain.
Department of Radiology, Physiotherapy and Rehabilitation, Faculty of Medicine, Complutense University of Madrid, Pl. de Ramón y Cajal s/n, 28040 Madrid, Spain.
Sensors (Basel). 2025 Apr 19;25(8):2581. doi: 10.3390/s25082581.
Multimodal imaging is valuable because it can provide additional information beyond that obtained from a conventional bright-field (BF) image and can be implemented with a widely available device. In this paper, we investigate the implementation of speckle-based transmission (T) and dark-field (DF) imaging in a laboratory X-ray setup to confirm its usefulness for material analysis. Three methods for recovering T and DF images were applied to a sample composed of six materials: plastic, nylon, cardboard, cork, expanded polystyrene and foam with different absorption and scattering properties. Contrast-to-noise ratio (CNR) and linear attenuation, absorption and diffusion coefficients obtained from BF, T and DF images are studied for two object-to-detector distances (ODDs). Two analysis windows are evaluated to determine the impact of noise on the image contrast of T and DF images and the ability to retrieve material characteristics. The unified modulated pattern analysis method proves to be the most reliable among the three studied speckle-based methods. The results showed that the CNR of T and DF images increases with larger analysis windows, while linear absorption and diffusion coefficients remain constant. The CNR of T images decreases with increasing ODD due to noise, whereas the CNR of DF images exhibits more complex behaviour, due to the material-dependent reduction in DF signal with increasing ODD. The experimental results on the ODD dependence of T and DF signals are consistent with recently reported numerical simulation results of these signals. The absorption coefficients derived from T images are largely independent of the ODD and the speckle-based method used, making them a universal parameter for material discrimination. In contrast, the linear diffusion coefficients vary with the ODD, limiting their applicability to specific experimental configurations despite their notable advantages in distinguishing materials. These findings highlight that T and DF images obtained from a laboratory X-ray setup offer complementary insights, enhancing their value for material analysis.
多模态成像很有价值，因为它能够提供超越传统明场（BF）图像所获得的额外信息，并且可以通过一种广泛可用的设备来实现。在本文中，我们研究了在实验室X射线装置中基于散斑的透射（T）和暗场（DF）成像的实现，以确认其在材料分析方面的有用性。三种恢复T和DF图像的方法被应用于由六种材料组成的样本：塑料、尼龙、硬纸板、软木塞、发泡聚苯乙烯和泡沫，这些材料具有不同的吸收和散射特性。针对两个物体到探测器的距离（ODD），研究了从BF、T和DF图像获得的对比度噪声比（CNR）以及线性衰减、吸收和扩散系数。评估了两个分析窗口，以确定噪声对T和DF图像的图像对比度的影响以及检索材料特性的能力。在三种研究的基于散斑的方法中，统一调制模式分析方法被证明是最可靠的。结果表明，T和DF图像的CNR随着分析窗口的增大而增加，而线性吸收和扩散系数保持不变。由于噪声，T图像的CNR随着ODD的增加而降低，而DF图像的CNR表现出更复杂的行为，这是由于随着ODD的增加，DF信号因材料而异的衰减。关于T和DF信号对ODD依赖性的实验结果与最近报道的这些信号的数值模拟结果一致。从T图像导出的吸收系数在很大程度上与ODD和所使用的基于散斑的方法无关，使其成为用于材料鉴别的通用参数。相比之下，线性扩散系数随ODD而变化，尽管它们在区分材料方面具有显著优势，但限制了它们在特定实验配置中的适用性。这些发现突出表明，从实验室X射线装置获得的T和DF图像提供了互补的见解，提高了它们在材料分析中的价值。
