%0 Journal Article
%T Mathematical Methods in Biomedical Optics
%A Macaveiu Gabriela
%J ISRN Biomedical Engineering
%D 2013
%R 10.1155/2013/464293
%X This paper presents a review of the phenomena regarding light-tissue interactions, especially absorption and scattering. The most important mathematical approaches for modeling the light transport in tissues and their domain of application: ¡°first-order scattering,¡± ¡°Kubelka-Munk theory,¡± ¡°diffusion approximation,¡± ¡°Monte Carlo simulation,¡± ¡°inverse adding-doubling¡± and ¡°finite element method¡± are briefly described. 1. Introduction When tissues are exposed to light reflection, refraction, absorption, or scattering can occur, which lead to energy losses in the incident beam. Refraction is not significant in biomedical applications, except for laser irradiation of transparent media, such as cornea tissue; in opaque media the most important phenomena are scattering and absorption, depending on the material type of the tissue and the incident wavelength. Knowledge of absorbing and scattering properties of the tissues is needed for predicting success of laser surgery treatment. Direct measurement methods simply use the Beer attenuation law, but they need corrections when surface reflections occur due to the mismatched refractive indexes. Indirect techniques use theoretical models for the scattering phenomena; the indirect noniterative methods need simple equations to connect optical properties to the measured quantities, while the indirect iterative methods can develop sophisticated models in which the optical properties are iterated until the computed reflection and transmission match the measured values. 2. Basic Phenomena Regarding Light and Tissues Reflection means the electromagnetic waves return from surfaces upon they are incident, generally being boundary surfaces between two materials of different refractive indexes, such as air and tissue. The simple law of reflection states that the reflection angle equals the incidence angle, while the surface is supposed to be smooth, having small irregularities compared to the radiation wavelength. The real tissues do not act like optical mirrors; the roughness of the reflecting surface leads to multiple beam reflections (diffuse reflection). Refraction means a displacement of the transmitted beam through the surface that separates two media with different refractive indexes, and it originates from the change of the speed of light passing through the surface. Refraction usually occurs together with reflection; the reflectivity of a surface is a measure of the amount of reflected radiation, and it is the ratio of the reflected and incident electric field amplitudes. The reflectance is the ratio of the reflected
%U http://www.hindawi.com/journals/isrn.biomedical.engineering/2013/464293/