基于汤姆逊散射X光源的高效散射成像研究

The performance gap between large-scale synchrotron radiation facilities and conventional x-ray tubes has been filled by the Thomson scattering x-ray source, since it can provide excellent x-ray beams and has small footprint and moderate cost. Hence, this type of light source is very suitable for x-ray imaging at laboratories and hospitals. In the field of x-ray imaging, scattering imaging contains abundant information about imaging objects and has many important applications in different fields, including medical imaging, material science, and nondestructive test. In this project, we will study scattering imaging combined with the characteristics of the Thomson scattering x-ray source. Key physical and technical problems associated with scattering imaging using this type of light source will be resolved. Highly efficient scattering imaging methods will be proposed and relevant Monte Carlo software will be developed to verify the possibility and efficiency of these methods. The quasi-monochromaticity of the Thomson scattering x-ray source will significantly improve the momentum resolution in coherent scattering imaging and the reconstruction precision in Compton scattering imaging; meanwhile, reasonable arrangement of the detector arrays according to the linearly polarized x-ray produced by this type of light source will also increase the utilization of scattered x-ray photons, hence, both radiation dose and imaging time will be reduced. Through the research of this project, a scattering imaging method with high precision and efficiency will be developed. This project will also promote the development of x-ray imaging using the Thomson scattering x-ray source and extend its application fields furtherly.

汤姆逊散射X光源以其优异的束流品质、紧凑的结构、相对低廉的造价弥补了大规模同步辐射与常规X光管之间性能的缺口，非常适合实验室和医院规模的X射线成像应用。在X射线成像领域，散射成像能够提供成像物体丰富的物理信息，在医学、材料科学、无损检测等诸多领域具有重要应用。本项目结合汤姆逊散射X光源的特性开展散射成像研究，解决其中关键的物理问题和技术问题，发展高效的散射成像方法，并开发相应的蒙特卡罗程序进行模拟验证。汤姆逊散射X光源准单色的特性可以显著提升相干散射的动量分辨率和康普顿散射的重建精度；另外，汤姆逊散射X光源能够产生线偏振X射线，利用线偏振X射线散射截面对散射角度的依赖性，合理安排成像布局能够有效提高散射光子的利用率，从而能够降低辐射剂量、缩短成像时间。本项目的研究将为X射线散射成像提供一种精准高效的方法，推动汤姆逊散射X光源成像技术的发展，进一步拓展其应用领域。

X射线散射成像能够提供成像物体丰富的物理信息，在医学、材料科学和无损检测等领域具有重要应用。面向此类应用的迫切需求，本项提出利用汤姆逊散射X光源发展高效的散射成像方法。首先，在理论上系统分析了线性和非线性汤姆逊散射条件下光源的偏振特性，为散射成像应用奠定了坚实基础；其次，利用光源的线偏振特性发展了高效的散射成像方法，并进行成像方案的设计和优化；最后，利用全尺寸的蒙特卡罗方法对成像方案进行了模拟，详细分析了成像系统的性能。结果表明，相比于传统X光源康普顿散射成像，本项目发展的康普顿散射成像方案可将成像效率提高1倍；另外，利用高通量的汤姆逊散射X光源（例如，10^13光子/秒），基于本项目发展的康普顿散射CT成像方案能够实现小动物的活体成像。这些结果将有助于推动散射成像技术和汤姆逊散射X光源的快速发展。

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