基于X射线调制的高分辨率X射线激发发光成像研究

X-ray luminescence tomography （XLT）can not only realize functional imaging specifically, but also overcome the disadvantages of optical imaging such as weak signal and signal noise interference. The development of XLT can be one important progress in imaging technology, especially in optical molecular imaging, whose potential and prospect get more and more attention. However, the scanning time is relatively long in narrow beam XLT while the imaging quality needs further improvement in cone beam XLT. Both the increase of scanning speed and the improvement of imaging quality cannot be realized in present XLT systems. In order to solve this problem, the X-ray luminescence tomography based on X-ray modulation is proposed. There are two aspects in the project: Firstly the X-ray modulated multi-area excitation is realized by X-ray modulation device, meanwhile the singular value decomposition method and chessboard-like scanning mode and reconstruction method are studied to realize fast and high resolution XLT based on X-ray modulation; Secondly, the influence of the X-ray modulation parameter on the XLT imaging is researched and the X-ray modulation mechanism is further improved to get rid of the constraints of beam width on the imaging quality in narrow beam XLT. With the above study, the XLT based on X-ray modulation can be achieved, which can fully utilize the X-ray and realize the improvement both in the scanning speed and in the imaging quality to further achieve the application and progress in XLT imaging.

X射线激发发光成像（XLT）不仅能够利用X射线实现特异性功能成像，还能够克服目前光学成像中存在的信号弱、背景噪声干扰的不足。XLT的发展可以进一步推动影像技术尤其是光学影像技术的进步，其发展潜力越来越受到重视。但是目前窄束XLT扫描时间过长而锥束XLT的成像质量有待提高，尚未有XLT成像系统能够兼顾扫描速度的提高和成像质量的改善。针对这一问题，本项目提出X射线调制的XLT成像研究。本项目从两方面入手研究：首先利用X射线调制装置完成X射线调制的多区域选择激发，采用基于奇异值分解和棋盘式智能化的重建方法，实现高分辨率的快速的XLT成像；同时研究X射线调制装置的参数对成像结果的影响，进一步设计和改进X射线调制激发机制，摆脱窄束XLT中射束宽度对成像质量的束缚。本项目拟通过上述研究内容，实现基于X射线调制的XLT成像，并实现扫描速度和成像质量的双重提高，进一步拓展XLT成像的应用和发展。

在XLT成像中，尽管已经实现了在体成像，但是如何有效的设计和改进XLT的激发机制，摆脱这种系统条件对成像质量的约束，一直是XLT成像系统中的软肋。本项目研究和构建基于X射线调制的XLT成像，能够实现同时产生多束平行的X射线束，重复利用X射线的选择激发改善成像质量，又提高成像效率。项目开展中，我们设计了X射线调制器，并对X射线调制器的参数进行了测试。基于这样的参数设计，我们研究了融合X射线束分布特点的多维扫描的XLT成像设计，并使用了优化算法克服重建问题的病态性和重建结果趋于表面的问题。我们尝试使用分级算法优化重建过程，测试了不同组织切片对于实验材料的光学性质，并进行了在体实验。研究结果说明我们设计的X射线调制的XLT成像方法能够提高成像质量，有助于推进XLT成像的发展。但是在实际开展时，对于X射线调制器的参数设计还有待进一步深入研究，受限于实验材料对于目标的特异性欠缺，在体实验的展开还有待加强。