Influence of absorption in linear polarization imaging of melanoma tissues

Dongzhi Li,Honghui He,Weidong Xie,Jian Wu,Nan Zeng,Hui Ma,Ran Liao,Yonghong He

doi:10.1142/s1793545814500096

Abstract

The contrast mechanism of different polarization imaging techniques for melanoma in mouse skin is studied using both experiments and Monte Carlo simulations. Total intensity, linear polarization difference imaging (DPI), degree of polarization imaging (DOPI) and rotating linear polarization imaging (RLPI) are applied and the relative contrasts of these polarization imaging methods between the normal and cancerous tissues are compared. A two-layer absorption-scattering model is proposed to explain the contrast mechanism of the polarization imaging for melanoma. By taking into account of both scattering of symmetrical and asymmetrical scatterers and absorption of inter-scatterer medium, the two-layer model reproduces the relative contrasts for polarization images observed in experiments. The simulation results also show that, the parameters of polarization imaging change more dramatically with the variation of absorption in the bottom layer than the top layer.

Highlights

Optical properties of biological tissues are often a®ected by their physiological and pathological statuses.[1,2,3,4] the normal and diseased tissues can be distinguished by measuring the changes of physical parameters in the interaction between light and biological tissues.[5,6] as most of the biological tissues are highly turbid in the visible and near-infrared region, multiple scattering of photons will degrade the contrasts of optical images.[7]
We study the melanoma using the rotating linear polarization imaging (RLPI) method, and compare the imaging contrasts with those of di®erence polarization imaging method (DPI) and degree of polarization imaging (DOPI) methods
We use this system on two melanoma samples, the results are shown in Figs. 2 and 3, respectively

Summary

Introduction

Optical properties of biological tissues are often a®ected by their physiological and pathological statuses.[1,2,3,4] the normal and diseased tissues can be distinguished by measuring the changes of physical parameters in the interaction between light and biological tissues.[5,6] as most of the biological tissues are highly turbid in the visible and near-infrared region, multiple scattering of photons will degrade the contrasts of optical images.[7]. Jacques et al.[7] proposed the degree of polarization imaging method (DOPI), in which the di®erence of polarization is normalized Both DPI and DOPI methods have been applied in demarcating the margins of cancerous tissues.[7,8,9,10] Recently, we have developed rotating linear polarization imaging (RLPI) and applied it to cancerous liver tissues.[11,12] The RLPI method provides a new set of parameters for quantitative characterization of the optical and structural properties for biological tissues and a new tool for clinical biomedical diagnosis.[11,12,13]. These parameters are independent of incident polarization angle (i) and detection polarization angle (s) These parameters are related to di®erent structural or optical properties of the sample, such as density, shape and size of the scatterers, as well as the direction and alignment of thebers.[11,12,13] The RLPI parameters can be expressed as functions of Mueller matrix elements. Degree of polarization (DOP) are obtained corresponding to specic incident and detection polarization angles, s 1⁄4 i and s 1⁄4 i þ =2 shown as Eqs. (3) and (4)

MC simulation

Polarization imaging of melanoma

Simulation model for cancerous skin tissues

Conclusion