J Biomed Opt. 2014 Feb;19(2):026007. doi: 10.1117/1.JBO.19.2.026007.
Most methods for measuring light-tissue interaction focus on volume reflectance, while very few measure light transmission. In a previous work, we suggested investigating the influence of blood vessel diameter on photons exiting the tissue at all exit angles to receive the full scattering profile. By this method, we have shown that there is a central angle, i.e., the isobaric point, independent of blood vessel diameter. The vessel diameter changes the effective reduced scattering coefficient. However, both the scattering profile and the value of the isobaric point strongly depend on optical properties and the exact geometry of the tissue. In this study, we investigate the dependency of the isobaric point on tissue diameter and scattering coefficient in both two-dimensional and three-dimensional simulations. We show that the value of this point linearly depends on tissue diameter. The findings of this work solve the dilemma of whether to measure transmission or reflection since the isobaric point reduces by half the total amount of exiting photons. Furthermore, the full scattering profile is sensitive to changes in the scattering properties, but a single isobaric point to these changes is expected. If this point is not found, it is a diagnostic indication of an unexpected change in the tissue.
大多数测量光与组织相互作用的方法都集中在体积反射率上，而很少有方法测量光透射率。在之前的工作中，我们建议研究血管直径对所有出射角度处出射组织的光子的影响，以接收完整的散射分布。通过这种方法，我们已经表明存在一个中心角，即等压点，与血管直径无关。血管直径改变有效散射系数。然而，散射分布和等压点的值都强烈依赖于组织的光学特性和精确的几何形状。在这项研究中，我们在二维和三维模拟中研究了等压点对组织直径和散射系数的依赖性。我们表明，该点的值与组织直径呈线性关系。这项工作的结果解决了测量透射还是反射的难题，因为等压点将出射光子的总量减少了一半。此外，完整的散射分布对散射特性的变化很敏感，但预计只有一个等压点对这些变化敏感。如果没有找到这个点，那么它就是组织发生意外变化的诊断指示。
