Scatter enhanced 3D X-ray imaging

低质量的x射线图像给机场等场所的x射线安检人员带来了严重的问题。操作员在包含杂乱日常物品的图像中搜索恐怖主义武器，如枪支、刀具或爆炸装置。在“典型的”行李箱或随身行李中检测和识别威胁大致可分为两个方面。也就是说，通过解释杂乱的图像来揭示威胁“形状”的存在，并通过产生材料特征信号来识别潜在的有害或爆炸性物质。前者依赖于空间信息，由于无法定义威胁的完整成员集，因此最好由人类操作员处理，而后者需要适当的传感器技术来为生成的图像的颜色编码提供原始数据。与托运行李检查和随身行李有关的后勤问题不容忽视。例如，每年大约有6800万人通过希思罗国际机场。环境类似于大批量生产线，其中每个要检查的项目都是不同的。这是一项独特而特别困难的检查任务。诺丁汉特伦特大学和克兰菲尔德大学的研究人员正在开发一种新型3D x射线扫描仪技术。该成像技术将强大的3D图像与区分危险物质和无害行李内容的能力相结合。他们与位于圣奥尔本斯的内政部科学发展部（HOSDB）的科学家合作，正在开发一种技术，该技术将提供视频类型的图像序列，准确地突出显示被检查物体的材料组成。动态图像通过一种强大而引人注目的三维结构感，为观察者提供了迄今为止未见过的有关被检查对象实际内容的信息。该技术的一个有趣的方面是，所得到的图像是来自复杂的集成传感器排列的各种信号贡献的合成。特征散射信号与高分辨率质量识别图像的结合有可能提供快速和空间精确的材料识别。为了实现这种新方法所需的集成探测器，杜伦科学晶体有限公司（从杜伦大学物理系分离出来的公司）的科学家们正在开发单晶形式的化合物半导体，如碲化镉。这个由英国领导的项目汇集了许多及时的创新，涉及动态3D x射线图像的生产和半导体传感器对x射线的直接检测。开发世界上第一个散射增强3D x射线扫描仪的关键现在依赖于建立传感器配置的精确要求，以及它们的几何、时间、光谱和电子特性。除了有可能显著提高目视检查的效率外，这项研究还将为有关开发用于自动探测爆炸性物质的计算方法的更大工作提供信息。从更长远的角度来看，这种方法的成功意义深远，因为该技术很有可能改善货运和/或车辆的高能x射线筛查以及医疗和工业应用。

Poor quality X-ray images pose serious problems for the security operators manning X-ray scanners at places such as airports. The operators search for the weapons of terrorism such as guns, knives or explosive devices in images containing the clutter of everyday items. The detection and identification of a threat in a 'typical' suitcase or carry-on bag may be categorised broadly into two areas. Namely, the interpretation of cluttered images to reveal the presence of a threat 'shape' and the identification of potentially harmful or explosive substances through the production of material characteristic signals. The former, is reliant upon spatial information, which is best dealt with by a human operator as the full member set of threats cannot be defined, while the latter requires an appropriate sensor technology to provide the raw data for colour encoding of the resultant images. The logistical problems associated with hold-baggage screening and carry-on baggage cannot be understated. For instance, approximately 68 million people pass through Heathrow International Airport each year. The environment is akin to a high volume production line in which each item to be inspected is different. This is a unique and particularly difficult inspection task.Researchers from the Nottingham Trent University and Cranfield University are developing a new type of 3D X-ray scanner technology. The imaging technique combines powerful 3D imagery with the capability to discriminate between dangerous substances and benign luggage contents. In collaboration with scientists based at the Home Office Scientific Development Branch (HOSDB) at St Albans, they are developing a technology that will provide video type image sequences accurately highlighting the material composition of the objects under inspection. The dynamic imagery provides the observer with hitherto unseen information concerning the actual contents of the objects being inspected through a powerful and compelling sensation of three-dimensional structure. An interesting aspect of the technique is that the resultant images are a synthesis of the various signal contributions from a complex arrangement of integrated sensors. The combination of characteristically scattered signals with high-resolution mass discrimination images has the potential to provide fast and spatially accurate materials discrimination. To realise the integrated detectors required for this novel approach, scientists at Durham Scientific Crystals Ltd a spin off company from the Physics Department at the University of Durham, are developing compound semiconductors such as cadmium telluride in single crystal form. This UK led project brings together a number of timely innovations concerning the production of dynamic 3D X-ray images and the direct detection of X-rays by semiconductor sensors.The key to developing the world's first scatter enhanced 3D X-ray scanner now relies upon establishing the precise requirements for the configuration of the sensors together with their geometric, temporal, spectral and electronic properties. Besides the potential to significantly improve the efficiency of visual inspection, the research will inform a larger body of work concerning the development of computational methods for the automatic detection of explosive substances. More futuristically the implications for the success of this approach are far reaching in that the technique may well have the potential to improve the high energy X-ray screening of freight and/or vehicles as well as medical and industrial applications.