Improved X-ray Cargo imaging by innovative background scattering quantification

x光检查是确保边境不受枪支、麻醉品和违禁品流入的高度优先事项。x射线筛查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此类非法材料的射线成像质量。在筛选货物和车辆时，使用高能高剂量脉冲线性加速器来产生x射线。检测包在单个脉冲的持续时间内集成信号，这构成了图像中每个像素值的基础。然而，由于没有办法阻止低能量光子散射到探测器或电子暗电流中，信号中包含了很大程度的噪声，从而扭曲了最终的放射成像图像。近年来的技术进步和光谱技术的开发为利用新型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。这将大大提高筛选系统的性能和提高图像质量，特别是在高衰减区域。为此，该项目寻求研究新的探测器材料，设计、建造和测试一个能够在如此高的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达斯伯里实验室的新型紧凑型加速器，它能够产生低剂量的x射线脉冲，以便开发控制探测包的算法并获得限制。然后，该检测包将在斯托克的Rapiscan系统工厂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 anx-ray screening system to detect photons attenuated by dense cargo directly affects the radiographic image quality that anoperator uses to identify such illicit material. When screening cargo and vehicles, high-energy high-dose pulsed linearaccelerators are used to generate the x rays. The detection package integrates the signal over the duration of a singlepulse and this forms the basis of each pixel value in the image. However, with no means to reject low-energy photonsscattered into the detectors or electronic dark current, the signals include a large degree of noise that distorts the finalradiographic images. The technological advances in recent years and the exploitation of spectroscopic techniques presentan 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 highattenuation. To this end, this project seeks to investigate new detector material, design, construct and test a prototypedetection system capable of photon counting in such high x-ray flux environments. Detector characterisation and design willbe carried out at the University of Manchester. Experimental investigations will require the use of the new Compact Linacfacility at Daresbury laboratory, capable of producing low-dose x-ray pulses so that algorithms to control the detectionpackage can be developed and the limitations obtained. The detection package will then be used at Rapiscan Systemsfacility at Stoke using a field-ready linac to prove its capabilities.