Friebel Moritz, Roggan André, Müller Gerhard, Meinke Martina
Laser- und Medizin- Technologie GmbH, Berlin, Germany.
J Biomed Opt. 2006 May-Jun;11(3):34021. doi: 10.1117/1.2203659.
The absorption coefficient mu(a), scattering coefficient mu(s), and anisotropy factor g of diluted and undiluted human blood (hematocrit 0.84 and 42.1%) are determined under flow conditions in the wavelength range 250 to 1100 nm, covering the absorption bands of hemoglobin. These values are obtained by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation (IMCS). With a new algorithm, appropriate effective phase functions could be evaluated for both blood concentrations using the IMCS. The best results are obtained using the Reynolds-McCormick phase function with the variation factor alpha = 1.2 for hematocrit 0.84%, and alpha = 1.7 for hematocrit 42.1%. The obtained data are compared with the parameters given by the Mie theory. The use of IMCS in combination with selected appropriate effective phase functions make it possible to take into account the nonspherical shape of erythrocytes, the phenomenon of coupled absorption and scattering, and multiple scattering and interference phenomena. It is therefore possible for the first time to obtain reasonable results for the optical behavior of human blood, even at high hematocrit and in high hemoglobin absorption areas. Moreover, the limitations of the Mie theory describing the optical properties of blood can be shown.
在流动条件下，于250至1100纳米波长范围内测定稀释和未稀释的人体血液（血细胞比容分别为0.84%和42.1%）的吸收系数μ(a)、散射系数μ(s)和各向异性因子g，该波长范围涵盖血红蛋白的吸收带。这些值通过高精度积分球测量结合优化的逆蒙特卡罗模拟（IMCS）获得。利用一种新算法，可通过IMCS为两种血液浓度评估合适的有效相位函数。血细胞比容为0.84%时，使用变化因子α = 1.2的雷诺兹 - 麦考密克相位函数，血细胞比容为42.1%时，α = 1.7，可获得最佳结果。将所得数据与米氏理论给出的参数进行比较。IMCS与选定的合适有效相位函数相结合，能够考虑红细胞的非球形形状、耦合吸收和散射现象以及多次散射和干涉现象。因此，即使在高血细胞比容和高血红蛋白吸收区域，首次有可能获得人体血液光学行为的合理结果。此外，还能展示米氏理论描述血液光学性质的局限性。
