Increased material differentiation through multi-contrast x-ray imaging: a preliminary evaluation of potential applications to the detection of threat materials
Increased material differentiation through multi-contrast x-ray imaging: a preliminary evaluation of potential applications to the detection of threat materials
复制标题
通过多对比 X 射线成像增加材料区分：对检测威胁材料的潜在应用的初步评估
DOI：
10.1088/1402-4896/ace939
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发表时间：
2023
期刊：
影响因子：
2.9
通讯作者：
Astolfo A
中科院分区：
文献类型：
--
作者：
Astolfo A
安全检查中的大多数材料识别是基于双能X射线成像，这使得能够确定一种材料的有效原子序数和电子密度，并由此将其归类为有机或无机。最近出现了基于相的“暗场”X射线成像方法，这种方法对材料的互补特征敏感，即其未分辨的微结构。因此，可以推测，将它们包含在基于安全的成像中可以增强对材料的识别，例如，具有相似的电子密度和Zeff值但不同微结构的材料。在这篇文章中，我们提出了一个初步的评估，这样的组合可以带来的优势。将能量分辨探测器用于基于相位的暗场技术，可同时提供双能量衰减和暗场图像。此外，由于我们使用了一种基于衰减X射线掩模的方法来产生暗场图像，因此通过利用透过高吸收掩模隔膜的X射线，可以获得具有更高光子能量的第五幅(衰减)图像。在第一个测试中，威胁材料与非威胁材料进行成像，我们展示了它们基于通过两个和五个成像通道的线性组合最大化其相对对比度而进行的识别如何在后一种情况下导致改进。然后，我们给出了第二个例子，说明了如何将该方法扩展到对多个非威胁材料进行区分，获得了类似的结果。尽管这些结果是初步的，但这些结果表明，通过在扫描过程中加入额外的X射线对比度，材料辨别力的改善幅度很大。
Most material discrimination in security inspections is based on dual-energy x-ray imaging, which enables the determination of a material's effective atomic number (Z eff) as well as electron density and its consequent classification as organic or inorganic. Recently phase-based'dark-field'x-ray imaging approaches have emerged that are sensitive to complementary features of a material, namely its unresolved microstructure. It can therefore be speculated that their inclusion in the security-based imaging could enhance material discrimination, for example of materials with similar electron densities and Z eff but different microstructures. In this paper, we present a preliminary evaluation of the advantages that such a combination could bear. Utilising an energy-resolved detector for a phase-based dark-field technique provides dual-energy attenuation and dark-field images simultaneously. In addition, since we use a method based on attenuating x-ray masks to generate the dark-field images, a fifth (attenuation) image at a much higher photon energy is obtained by exploiting the x-rays transmitted through the highly absorbing mask septa. In a first test, a threat material is imaged against a non-threat one, and we show how their discrimination based on maximising their relative contrast through linear combinations of two and five imaging channels leads to an improvement in the latter case. We then present a second example to show how the method can be extended to discrimination against more than one non-threat material, obtaining similar results. Albeit admittedly preliminary, these results indicate that significant margins of improvement in material discrimination are available by including additional x-ray contrasts in the scanning process.