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参与性介质内光学参数信息重建是目前辐射反问题的研究热点,广泛应用于生物医学成像等领域。荧光探针技术可以显著地提高生物体内健康组织与病变组织的对比度,在近红外光学成像领域受到了广泛的关注。本文利用扩散近似方程模拟激发激光和荧光在散射占优介质内的传输,求解介质边界的透反射信号。利用广义Gauss-Markov随机场模型构建正则化项,加入目标函数中以克服反问题的病态特性。采用共轭梯度法求解反问题,反演二维非均匀介质内的荧光产率和荧光寿命。结果表明,本文提出的算法能够很好地反演获得荧光产率和荧光寿命分布,所得图像能够清晰地分辨出介质内部结构。
Reconstruction of optical parameters in the participative medium is a hot research topic of the inverse problem of radiation and is widely used in the field of biomedical imaging. Fluorescent probe technology can significantly improve the contrast between healthy and diseased tissues in organism and has drawn much attention in the field of near-infrared optical imaging. In this paper, we use the diffusion approximation equation to simulate the transmission of the excitation laser and the fluorescence in the scattering dominant medium and solve the transreflective signal at the medium boundary. The regularization term is constructed by using the generalized Gauss-Markov random field model and added into the objective function to overcome the ill-posedness of the inverse problem. Conjugate gradient method was used to solve the inverse problem, and the fluorescence yield and fluorescence lifetime in two-dimensional inhomogeneous medium were inverted. The results show that the algorithm proposed in this paper can well obtain the fluorescence yield and fluorescence lifetime distribution, the image can clearly distinguish the internal structure of the medium.