Binzoni T, Leung T S, Rüfenacht D, Delpy D T
Département de Neurosciences Fondamentales, Faculty of Medicine, University of Geneva, Switzerland.
Phys Med Biol. 2006 Jan 21;51(2):311-33. doi: 10.1088/0031-9155/51/2/009. Epub 2006 Jan 4.
Based on quasi-elastic scattering theory (and random walk on a lattice approach), a model of laser-Doppler flowmetry (LDF) has been derived which can be applied to measurements in large tissue volumes (e.g. when the interoptode distance is >30 mm). The model holds for a semi-infinite medium and takes into account the transport-corrected scattering coefficient and the absorption coefficient of the tissue, and the scattering coefficient of the red blood cells. The model holds for anisotropic scattering and for multiple scattering of the photons by the moving scatterers of finite size. In particular, it has also been possible to take into account the simultaneous presence of both Brownian and pure translational movements. An analytical and simplified version of the model has also been derived and its validity investigated, for the case of measurements in human skeletal muscle tissue. It is shown that at large optode spacing it is possible to use the simplified model, taking into account only a 'mean' light pathlength, to predict the blood flow related parameters. It is also demonstrated that the 'classical' blood volume parameter, derived from LDF instruments, may not represent the actual blood volume variations when the investigated tissue volume is large. The simplified model does not need knowledge of the tissue optical parameters and thus should allow the development of very simple and cost-effective LDF hardware.
基于准弹性散射理论（以及晶格上的随机游走方法），已经推导出一种激光多普勒血流仪（LDF）模型，该模型可应用于大组织体积的测量（例如当光极间距离>30毫米时）。该模型适用于半无限介质，并考虑了经传输校正的组织散射系数和吸收系数以及红细胞的散射系数。该模型适用于各向异性散射以及光子被有限大小的移动散射体的多次散射。特别地，还能够考虑布朗运动和纯平移运动同时存在的情况。对于在人体骨骼肌组织中的测量情况，还推导了该模型的一个解析且简化的版本，并研究了其有效性。结果表明，在光极间距较大时，可以使用仅考虑“平均”光程长度的简化模型来预测与血流相关的参数。还证明了，当所研究的组织体积较大时，从LDF仪器得出的“经典”血容量参数可能并不代表实际的血容量变化。简化模型不需要了解组织光学参数，因此应该能够开发出非常简单且经济高效的LDF硬件。
