A New Generation of X-ray Baggage Scanners Based on a Different Physical Principle.
A New Generation of X-ray Baggage Scanners Based on a Different Physical Principle.
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DOI：
10.3390/ma4101846
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发表时间：
2011-10-17
期刊：
影响因子：
--
通讯作者：
Olivo A
中科院分区：
文献类型：
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作者：
Ignatyev K;Munro PRT;Chana D;Speller RD;Olivo A
x光行李扫描仪在保护机场、海关和其他具有重要战略意义的建筑物和基础设施方面发挥着基本作用。目前的行李扫描仪技术是基于x射线衰减的，这意味着对威胁物体的检测依赖于不同物体如何不同地衰减穿过它们的x射线束。双能x射线扫描仪的使用增强了这种能力，通过拍摄不同x射线光谱的图像并适当地组合信息，可以更精确地确定材料的x射线衰减特性。然而，当需要区分具有相似衰减特性的物体时，这种方法仍然存在局限性。我们描述了一种基于不同的x射线相互作用现象的替代方法，x射线折射。折射在可见光中是一种常见的现象（例如，是什么使半浸入一杯水中的吸管看起来弯曲），在x射线中也会发生，只是在小得多的角度上造成偏差。通常，这些偏差发生在所有物体的边界。我们已经开发了一个系统，像其他基于“相位对比”的仪器一样，能够检测到这种偏差，因此可以创建所有物体轮廓的精确图像。这补充了x射线衰减所提供的与材料相关的信息，并有助于了解单个物体的性质，从而提高了行李扫描仪的灵敏度（提高了检出率）和特异性（降低了误报率）。
X-ray baggage scanners play a basic role in the protection of airports, customs, and other strategically important buildings and infrastructures. The current technology of baggage scanners is based on x-ray attenuation, meaning that the detection of threat objects relies on how various objects differently attenuate the x-ray beams going through them. This capability is enhanced by the use of dual-energy x-ray scanners, which make the determination of the x-ray attenuation characteristics of a material more precise by taking images with different x-ray spectra, and combining the information appropriately. However, this still has limitations whenever objects with similar attenuation characteristics have to be distinguished. We describe an alternative approach based on a different x-ray interaction phenomenon, x-ray refraction. Refraction is a familiar phenomenon in visible light (e.g., what makes a straw half immersed in a glass of water appear bent), which also takes place in the x-ray regime, only causing deviations at much smaller angles. Typically, these deviations occur at the boundaries of all objects. We have developed a system that, like other “phase contrast” based instruments, is capable of detecting such deviations, and therefore of creating precise images of the contours of all objects. This complements the material-related information provided by x-ray attenuation, and helps contextualizing the nature of the individual objects, therefore resulting in an increase of both sensitivity (increased detection rate) and specificity (reduced rate of false positives) of baggage scanners.