T-matrix computations of light scattering by red blood cells
T-matrix computations of light scattering by red blood cells
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DOI：
10.1364/ao.37.002735
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发表时间：
1998-05-01
期刊：
影响因子：
1.9
通讯作者：
Andersson-Engels, S
中科院分区：
文献类型：
--
作者：
Nilsson, AMK;Alsholm, P;Andersson-Engels, S
利用T矩阵理论分析了光与红细胞（RBC）体积等效球体相互作用产生的电磁远场和近场。该方法是一种强大的工具，可以研究细胞形状对散射光角分布的影响。一般的意见是，三维形状，以及明显的入射场的光学厚度，影响前向散射。后向散射受面对入射光束的表面形状的影响。此外，将扁形RBC分别成球和伸长成体积等效球体或长球体在理论上建模以模拟生理现象，通过热或弯曲血液的增加的剪切应力。球化和伸长都被证明会降低前向散射的强度，从而产生较低的g因子。球化使得散射图案独立于方位角散射角phi（s），而伸长诱导更明显的依赖于phi（s）的图案。因此，发现红细胞体积等效球体的光散射受散射物体的形状的高度影响。近场半径r（nf）被评价为总近场的最大强度降低到保持入射的最大强度的2.5倍的距离。据估计，它是散射球体最大半径的2-24.5倍，相当于12-69 μ m。由于近场半径被证明是大于一个简单的估计之间的距离的红细胞在全血中，独立散射的假设，经常采用的光学测量全血，似乎不合适。这也表明，不能通过乘以简单的浓度因子将稀释血液所得结果外推至全血。(C)1998年美国光学学会。
The electromagnetic far field, as well as the near field, originating from Light interaction with a red blood cell (RBC) volume-equivalent spheroid, was analyzed by utilizing the T-matrix theory. This method is a powerful tool that makes it possible to study the influence of cell shape on the angular distribution of scattered light. General observations were that the three-dimensional shape, as well as the optical thickness apparent to the incident field, affects the forward scattering. The backscattering was influenced by the shape of the surface facing the incident beam. Furthermore sphering as well as elongation of an oblate RBC into a volume-equivalent sphere or a prolate spheroid, respectively, was theoretically modeled to imitate physiological phenomena caused, e.g., by heat or the increased shear stress of bowing blood. Both sphering and elongation were shown to decrease the intensity of the forward-directed scattering, thus yielding lower g factors. The sphering made the scattering pattern independent of azimuthal scattering angle phi(s), whereas the elongation induced more apparent phi(s)-dependent patterns. The Light scattering by a RBC volume-equivalent spheroid was thus found to be highly influenced by the shape of the scattering object. A near-field radius r(nf) was evaluated as the distance to which the maximum intensity of the total near field had decreased to 2.5 times that of the incident held. It was estimated to 2-24.5 times the maximum radius of the scattering spheroid, corresponding to 12-69 mu m. Because the near-field radius was shown to be larger than a simple estimation of the distance between the RBC's in whole blood, the assumption of independent scattering, frequently employed in optical measurements on whole blood, seems inappropriate. This also indicates that one cannot extrapolate the results obtained from diluted blood to whole blood by multiplying with a simple concentration factor. (C) 1998 Optical Society of America.