Modeling of light scattering by biconcave and deformed red blood cells with the invariant imbedding T-matrix method

Lei Bi,Ping Yang

doi:10.1117/1.jbo.18.5.055001

Abstract

The invariant imbedding T-matrix method (II-TM) is employed to simulate the optical properties of normal biconcave and deformed red blood cells (RBCs). The phase matrix elements of a RBC model computed with the II-TM are compared with their counterparts computed with the discrete-dipole approximation (DDA) method. As expected, the DDA results approach the II-TM results with an increase in the number of dipoles per incident wavelength. Computationally, the II-TM is faster than the DDA when multiple RBC orientations are considered. For a single orientation, the DDA is comparable with or even faster than the II-TM because the DDA efficiently converges for optically soft particles; however, the DDA method demands significantly more computer memory than the II-TM. After the applicability of the II-TM is numerically confirmed, a comparison is conducted of the optical properties of oxygenated and deoxygenated RBCs and of normal and deformed RBCs. The spectral variations of RBCs' optical properties are investigated in the wavelength range from 0.25 to 1.0 μm. Furthermore, the statistically averaged phase matrix of spheres and biconcave RBCs are compared. Conducted numerical simulations suggest the applicability of the II-TM for the inverse light scattering analysis and radiative transfer simulations in blood.

Highlights

Red blood cells (RBCs) or erythrocytes flowing in blood are responsible for the delivery of oxygen from the lungs throughout the human body and the return transport of CO2 from the tissues to the lungs
Several reasons exist for comparing the imbedding T-matrix method (II-TM) and the discrete-dipole approximation (DDA) in the computation of RBC optical properties
The II-TM has been applied to the simulation of optical properties of single RBCs

Summary

Introduction

Red blood cells (RBCs) or erythrocytes flowing in blood are responsible for the delivery of oxygen from the lungs throughout the human body and the return transport of CO2 from the tissues to the lungs. RBCs have specific biophysical properties for responding to a change in the local chemical and mechanical environment. The deviations from regular biophysical properties of RBCs impair their normal functions in the human body and are sensitive markers for various blood disorders and diseases, e.g., malaria and sickle cell anemia. For this reason, relevant techniques to obtain the characteristics of the biophysical properties of RBCs have been of paramount significance in medical diagnostics. Optical techniques have been considerably investigated as they provide a fast and noninvasive pathway to probe cell changes. Some of the well-known examples of optical techniques are flow cytometers,[1,2] quantitative phase imaging,[3,4] and Fourier transform light scattering.[5]

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