Ultrafast laser x-ray in-vivo phase-contrast micro-CT

描述(申请人提供)：新兴的光子技术，如超快激光，为克服传统生物医学成像模式的局限性提供了新的范例。在这个项目中，我们建议开发在线X射线相衬微型CT系统，该系统将利用基于超快激光的X射线源(ULX)。这种新的光源通过激光照射固体靶来产生X射线。任何固体(金属或非金属)都可以用作靶子。ULX在X射线中提供的能量比传统微焦管所能提供的能量更大，因此可以进行更快的扫描。此外，ULX产生的X射线光谱很窄，主要由特征线组成。这些都可以很容易地为成像任务量身定做(通过改变激光目标)。相衬显微CT将允许高分辨率测量活体动物的X射线折射率的实部(x射线相移)和虚部(x射线吸收)的空间分布。这与传统的微型CT不同，它使用的是微焦点X射线管，它只能绘制X射线吸收系数的3D分布。因此，我们预计，除了传统的吸收图测量之外，打开X射线相移3D映射提供的新信息通道，将在不增加任何剂量的情况下显著提高Micro-CT的软组织低对比度分辨率，从而改善小动物模型中的癌症成像。在适当的时候，这种方法可以扩展到临床CT扫描仪，前提是可以获得高平均功率的超快激光。 紧凑型、坚固耐用、超快的激光器在商业上可以买到，它们的特性正在迅速改善。我们计划构建和探索体内直线式X射线相位对比度ULX微型CT系统的成像性能。这一目标将通过完成以下任务来实现：i)通过计算机模拟最佳系统几何结构和焦点大小和形状的设计和优化；ii)通过计算机模拟ULX光谱的设计和优化；iii)所选系统设计的实验实施和优化；iv)开发图像处理工具，用于校正、提取、增强和融合提取的相衬和吸收断层扫描数据以及改进吸收和相衬图像的融合；V)组装了锥束ULX相衬显微CT系统(优化了几何形状、能量、焦斑和探测器)，利用模体和口腔癌小鼠模型的活体成像，开始探索整个系统的成像性能，并与传统的Micro-CT进行比较。

DESCRIPTION (provided by applicant): Emerging photonic technologies, such as ultrafast lasers, provide a new paradigm for overcoming the limitations of traditional biomedical imaging modalities. In this project, we propose to develop in-line x-ray phase-contrast micro-CT system that will utilize an ultrafast laser-based x-ray (ULX) source. This new source produces x-rays through irradiation of a solid target by the laser beam. Any solid (metal or non-metal) can be used as a target. ULX delivers more power in x-rays than a conventional microfocal tube is able to provide, thus allowing for much faster scans. Further, ULX generates narrow x-ray spectra that consist mainly of characteristic lines. These can be easily tailored (by changing laser beam target) to the imaging task. The phase-contrast micro-CT will allow high-resolution measurements of the spatial distribution of the real (x-ray phase-shift) and the imaginary (x-ray absorption) components of the x-ray refractive index in a living animal. This is in contrast to conventional micro-CT, using a microfocal x-ray tube, which can only map 3D distribution of the x-ray absorption coefficient. Therefore, we expect that'opening the new channel of information provided by the x-ray phase-shift 3D mapping, in addition to conventional absorption map measurement, will significantly increase soft tissue low-contrast resolution of micro-CT without any dose increase, thus allowing improved imaging of cancer in small animal models. In due course, this method could be expanded to clinical CT scanners, providing that the high average power ultrafast lasers become available. Compact, robust, ultrafast lasers are commercially available, and their characteristics are rapidly improving. We plan to construct and explore imaging performance of an in vivo in-line x-ray phase-contrast ULX micro-CT system. This goal will be accomplished by completing the following tasks: i) design and optimization via computer simulations of the optimal system geometry and the focal spot size and shape; ii) design and optimization via computer simulations of ULX spectra; iii) experimental implementation and optimization of the selected system design; iv) development of image processing tools for correction, extraction, enhancement, and fusion of the extracted phase-contrast and absorption tomographic data and improved fusion of absorption and phase-contrast images; v) assemble a cone-beam ULX phase-contrast micro-CT system (with optimized geometry, energy, focal spot, and detector) and begin exploration of the imaging performance of the whole system and comparison with conventional micro-CT, using phantoms and in vivo imaging of oral cancer mouse model.