Improved X-ray cargo imaging using a novel high-throughput fast-detector setup.

为了保护边境不受枪支、毒品和违禁品流入的影响，X射线检查是高度优先的。X射线扫描系统探测被密集货物衰减的光子的能力直接影响操作员用来识别这种非法材料的射线图像质量。在检查货物和车辆时，使用高能、高剂量脉冲直线加速器来产生X射线。检测组件在单个脉冲的持续时间内对信号进行积分，这形成了图像中每个像素值的基础。然而，由于没有办法抑制散射到探测器中的低能量光子或电子暗电流，信号中包含很大程度的噪声，从而扭曲了最终的射线图像。近年来的技术进步和光谱技术的开发为利用新的探测器材料和现成的快速电子元件来识别单个光子提供了机会。这将极大地改善加网系统的性能并提高图像质量，特别是在高衰减区域。为此，本项目致力于研究新的探测器材料，设计、建造和测试能够在如此高X射线通量环境中进行光子计数的原型探测系统。探测器的特性和设计将在曼彻斯特大学进行。实验研究将需要使用位于达累斯伯里实验室的新的紧凑型直线加速器设施，该设施能够产生低剂量的X射线脉冲，以便能够开发控制探测包的算法并获得限制。然后，探测包将用于位于斯托克的Rapiscan系统设施，使用现场就绪的直线加速器来证明其能力。

X-ray screening is high priority for securing borders from the influx of firearms, narcotics, and contraband. The ability of an x-ray screening system to detect photons attenuated by dense cargo directly affects the radiographic image quality that an operator uses to identify such illicit material. When screening cargo and vehicles, high-energy high-dose pulsed linear accelerators are used to generate the x rays. The detection package integrates the signal over the duration of a single pulse and this forms the basis of each pixel value in the image. However, with no means to reject low-energy photons scattered into the detectors or electronic dark current, the signals include a large degree of noise that distorts the final radiographic images. The technological advances in recent years and the exploitation of spectroscopic techniques present an opportunity to utilise novel detector material and off-the-shelf fast electronic components to identify individual photons. This will vastly improve the performance of screening systems and increase image quality, particularly in areas of high attenuation. To this end, this project seeks to investigate new detector material, design, construct and test a prototype detection system capable of photon counting in such high x-ray flux environments. Detector characterisation and design will be carried out at the University of Manchester. Experimental investigations will require the use of the new Compact Linac facility at Daresbury laboratory, capable of producing low-dose x-ray pulses so that algorithms to control the detection package can be developed and the limitations obtained. The detection package will then be used at Rapiscan Systems facility at Stoke using a field-ready linac to prove its capabilities.