基于蒙特卡罗模拟的散射介质中后向光散射模型及分析应用

构建了内光源模型探讨散射介质中的光散射现象，利用蒙特卡罗方法研究了逃逸出组织的后向散射光子数随光子在组织内部发生的散射次数的分布关系，探讨了光源照明方式、辐射强度、接收方式、调制等参数的变化对后向散射的影响，结果表明后向散射光子的数量随散射次数的分布并非简单的单调递增或递减，而是一条先增大后减小出现峰值的曲线. 峰值位置、峰值大小及曲线形状与光源、探测方式、组织光学特性参数等有关.关键词：医用光学与生物技术散射介质后向散射蒙特卡罗模拟

Discussion on backscattered photon numbers and their scattering events in a turbid media

Due to strong scattering, most optical tomography techniques can't achieve practical imaging depth in turbid media such as bio-tissues. In this paper a new inner-light-source model was proposed and Monte Carlo method was used to analyze related problems. The distribution of backscattered photon number against the number of their scattering events was studied, and various illumination geometries and detecting methods were simulated. The results show that instead of rashly assuming that the number of photons reemitted from the tissue monotomically increases or decreases as scattering events accumulates; the backscattered photon number actually increases firstly and decreases later. The peak position, peak value and curve shape depend on the illumination geometry, monitoring method and tissue optical parameters.