Empirical model functions to calculate hematocrit-dependent optical properties of human blood

Abstract

The absorption coefficient, scattering coefficient, and effective scattering phase function of human red blood cells (RBCs) in saline solution were determined for eight different hematocrits (Hcts) between 0.84% and 42.1% in the wavelength range of 250-1100 nm using integrating sphere measurements and inverse Monte Carlo simulation. To allow for biological variability, averaged optical parameters were determined under flow conditions for ten different human blood samples. Based on this standard blood, empirical model functions are presented for the calculation of Hct-dependent optical properties for the RBCs. Changes in the optical properties when saline solution is replaced by blood plasma as the suspension medium were also investigated.

Optical Monitoring of Tumors in BALB/c Nude Mice Using Optical Coherence Tomography

“…The effect of the epidermal layer on tissue attenuation is relatively restricted because of its thinness. The attenuation constant in whole blood, mainly due to light scattering by red blood cells, is known to be as large as about 670 cm -1 at 960 nm [22,23]. Therefore, due to dense vasculature, tumor tissues had more optical attenuation by a few hundred cm -1 than the normal tissues.…”

Hematocrit dependence of flow signal in optical coherence tomography angiography

“…Figure 1(A) shows the scattering coefficient s μ as a function of the HCT at 840 nm. The black solid line is based on Twersky's formula [30] and the red dash line is based on the empirical model function in [32]. As illustrated in the figure, the scattering coefficients increase with the increase of the HCT.…”

Calculation of photon path changes due to scatter in Monte Carlo simulations

“…The direction of travel of the photon is defined using the two spherical angles,  and , where (the zenith angle) is the angle between the photon's direction vector and the positive zaxis and (the azimuth angle) is the angle between the projection of the direction vector onto the x-y plane and the positive x-axis respectively. It is assumed that any exit angle within the cone of emission is equally probable, so the zenith angle,  is assigned an initial value given by =2 emm   (2) where is a uniformly distributed random number between 0 and 1, and…”

“…al. in 1995. The simulation program allows the user to specify the number of layers, the thickness of each layer as well as the absorption and scattering properties of each layer [2].…”

“…the photon would not change direction at all. For tissue, g is usually between 0.85 and 0.99, implying that small angle scattering is favoured [1,2].…”