生物组织中光子微区扩散理论研究

为合理描述生物组织中光子微区的扩散情况，提出在相函数中引入独立控制参量来改进现有的一般扩散近似理论。以平板结构为例，分别利用改进的一般扩散近似理论、标准扩散近似理论以及一般扩散近似理论，对光子在不同厚度中的扩散进行数值模拟，并与蒙特卡罗方法的模拟结果进行了比较，从而论证了改进的一般扩散近似理论能很好地描述生物组织中光子微区扩散。在此基础上，进一步探讨了系统参量对独立控制参量的影响。结果表明：最佳独立控制参量会随着数值孔径的增加而下降、随着光束半径的增加而增加。本研究对微区生物组织光学特性测量技术的研究具有重要的指导意义。

Photonics Diffusion for Small Source-Detector Separations of Tissue

A new control parameter is introduced to phase function to modify the general diffusion approximation for small source-detector separation of tissue. The results of standard diffusion approximation, general diffusion approximation and modified general diffusion approximation are compared with the Monte-Carlo simulation in steady state diffusion equation for slab boundary condition. The result shows that the modified general diffusion approximation with an appropriate control parameter is more closed to Monte-Carlo simulation for local tissue, and describes exactly the photon propagation of small separation between source and detector. The effects of system parameters, such as numerical aperture and diameter of laser on the control parameter are also discussed. This study is useful for the measurement of optical properties of tissue with high resolution.