Alexandrakis G, Farrell T J, Patterson M S
Appl Opt. 2000 May 1;39(13):2235-44. doi: 10.1364/ao.39.002235.
We propose a hybrid Monte Carlo (MC) diffusion model for calculating the spatially resolved reflectance amplitude and phase delay resulting from an intensity-modulated pencil beam vertically incident on a two-layer turbid medium. The model combines the accuracy of MC at radial distances near the incident beam with the computational efficiency afforded by a diffusion calculation at further distances. This results in a single forward calculation several hundred times faster than pure MC, depending primarily on model parameters. Model predictions are compared with MC data for two cases that span the extremes of physiologically relevant optical properties: skin overlying fat and skin overlying muscle, both in the presence of an exogenous absorber. It is shown that good agreement can be achieved for radial distances from 0.5 to 20 mm in both cases. However, in the skin-on-muscle case the choice of model parameters and the definition of the diffusion coefficient can lead to some interesting discrepancies.
我们提出了一种混合蒙特卡罗（MC）扩散模型，用于计算强度调制的笔形光束垂直入射到双层浑浊介质上所产生的空间分辨反射幅度和相位延迟。该模型将入射光束附近径向距离处MC的精度与更远距离处扩散计算所提供的计算效率相结合。这使得单次正向计算比纯MC快数百倍，主要取决于模型参数。针对两种涵盖生理相关光学特性极端情况的案例，将模型预测结果与MC数据进行了比较：脂肪上方的皮肤和肌肉上方的皮肤，均存在外源性吸收剂。结果表明，在这两种情况下，对于0.5至20毫米的径向距离都能实现良好的一致性。然而，在皮肤覆盖肌肉的情况下，模型参数的选择和扩散系数的定义可能会导致一些有趣的差异。
