基于空间光测量的光学层析成像系统研究

发布时间：2018-08-08 14:44

【摘要】：扩散光层析成像（Diffuse Optical Tomography，DOT）和荧光层析成像（Fluorescence Diffuse Optical Tomography，，FDOT）技术由于具有良好的特异性、实时性和安全性成为了成像研究的热点。非接触式测量可以获得大量的测量数据，并且避免了接触产生的耦合误差，具有广阔的应用前景。本文设计并搭建稳态域非接触式DOT/FDOT系统，采用EMCCD（Electron-Multiplying CCD）作为探测器并辅以待测体旋转平台，以增加源-探测点数量，快速获得大数据集，提高系统的空间分辨率。最终形成的系统包括激光器、EMCCD、电控平移台/精密电控旋转台、滤光轮和计算机。为了充分发挥该系统获取大数据集的优势，将系统中的各个部分进行集成，实现快速测量、数据采集与分析、成像结果实时显示的自动化控制。采用VisualStudio6.0编写系统的控制程序，实现在连续测量模式下，DOT/FDOT系统的自动化集成。基于此又研究了系统的校准方法，以减小像差和噪声对成像的影响。并研制了适用于上述非接触测量DOT/FDOT用仿体，对搭建的系统进行了DOT及FDOT仿体实验验证。在DOT测量中，分别采用不同的源扫描密度、不同吸收系数的异质体及不同中心距（the center-center separation，CCS）的目标体进行了实验，并结合本组已经发展的适合大测量数据集的DOT/FDOT重建算法进行了图像重建。结果表明：在最佳光源密度为16×16时，由该系统所获得的吸收系数的重建图像，能基本反映出异质体的形状、大小和位置；系统可以区分异质体在吸收系数上的差异，在异质体吸收对比度为2的情况下，重建图像的量化度高达70%；系统完全可以分辨最小距离为CCS=12mm的两个异质体。在FDOT测量中，分别采用不同的源扫描密度和不同荧光浓度的异质体进行了实验。结果表明：在最佳光源密度即每周30个点时，该系统所获得的荧光产率的重建图像可以基本反映异质体的形状、大小和位置；且系统可以检测出不同荧光浓度下的荧光产率变化。该DOT/FDOT系统有望在小动物成像方面发挥作用。
[Abstract]:Diffusion optical tomography (Diffuse Optical) and fluorescence tomography (Fluorescence Diffuse Optical) have become the focus of imaging research due to their good specificity. Non-contact measurement can obtain a lot of measurement data and avoid the coupling error caused by contact, so it has a broad application prospect. In this paper, a steady state non-contact DOT/FDOT system is designed and built. EMCCD (Electron-Multiplying CCD) is used as the detector and a rotating platform is used to increase the number of source-probe points, to obtain big data sets quickly and to improve the spatial resolution of the system. The resulting system consists of a laser EMCCD, an electrically controlled translation platform / a precision electrically controlled rotation table, a filter wheel and a computer. In order to give full play to the advantages of the system in obtaining big data sets, the system integrates all parts of the system to realize the automatic control of rapid measurement, data acquisition and analysis, and real-time display of imaging results. The automatic integration of DOT / FDOT system in continuous measurement mode is realized by programming the control program of the system with VisualStudio6.0. Based on this, the calibration method of the system is studied to reduce the influence of aberration and noise on the imaging. The simulant used in the above non-contact measurement of DOT/FDOT was developed. The system was verified by DOT and FDOT experiments. In the DOT measurement, different source scanning density, different absorption coefficient and different the center-center separation distance were used to carry out the experiments. Combined with the developed DOT/FDOT reconstruction algorithm for large measurement data sets, image reconstruction is carried out. The results show that when the optimum light density is 16 脳 16:00, the reconstructed image of the absorption coefficient obtained by the system can basically reflect the shape, size and location of the heterogeneity, and the system can distinguish the difference of the absorption coefficient of the heterogeneity. The quantization of the reconstructed image is as high as 70 when the absorption contrast of the heterostructure is 2, and the system can fully distinguish the two heterostructures with the minimum distance of CCS=12mm. In the FDOT measurement, different source scanning densities and different fluorescence concentrations were used to carry out the experiment. The results show that the reconstructed image of fluorescence yield obtained by the system can basically reflect the shape, size and location of the heterostructure when the optimal light density is 30 points per week. The system can detect the change of fluorescence yield under different fluorescence concentration. The DOT/FDOT system is expected to play a role in the imaging of small animals.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R310

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