Study Of Optics Energy Transmission And Distribution In Biological Tissues By Monte Carlo Method

Energy distribution in biological tissue has a very important significance in laser biomedical information on the diagnosis and treatment. Monte Carlo method has been widely used in particle transport problem, but also fit in the same research organization in the light transport problem. Numerical results obtained by Monte Carlo method have become a non-test standards to compare the accuracy of various analytical theory of tissue optics.The basic idea of Monte Carlo method used in biological tissue optical energy transmission and distribution is: using the principle of absorption and scattering of photons to track the process through the medium of chaos; through a large number of photon statistics of simulation results to obtain the distribution of laser energy within the organization.Firstly, the paper provides an overview of the development of optical organize and research mission; points out the research significance of light energy transferring in biological tissue; introduces the study history and the current situation of light energy distribution.Secondly, introduce the structural characteristics and optical properties of biological tissue, sum up the interaction of light with biological tissue of a number of ways, and focus on discussing the physical meaning of the optical parameters. On this basis, introduce the transmission model and the diffusion equation from diffusion approximation, and get the answers of diffusion model equations in infinite and semi-infinite medium.Then, introduce the basic idea of Monte Carlo method and illustrate the use of this method of energy distribution in biological tissues. According to the previous introduction of biological organizational structure characteristics and theoretical basis, respectively give the optical model and simulation flow of single-layer and double-layer biological tissues. Photon's launching, absorbing, scattering, the probability sampling of direction and step-size, the relevant formula of absorption and scattering, colliding with boundary as well as the termination of a photon are introduced respectively. The differences of photon transmitting in double-layer or multilayer and single-layer are discussed in detail.Finally, the Monte Carlo simulation results of energy distribution in single-layer and double-layer tissues are analyzed. Firstly compared with the transfer theory, we know the correctness of Monte Carlo simulation in this paper. And then plot the photon track from the perspective of two-dimensional and three-dimensional image. Discuss the relationship between g factor and the loss energy from tissue surface. On this basis, analyze the transferring of light energy in single-layer and double-layer tissues respectively.Light intensity distribution with depths variation and optical parameters having what influence in energy aggradations of unlimited fine beam in single-layer tissues are presented. As to double-layer tissues, the rules of the energy density and energy absorption flow rate changing on the radial and vertical are discussed separately. The angle and the radius change, the radial and angular diffuse reflectance rate changes accordingly. This paper also simply analyzes the situation of Gaussian beam and flat light beam at two-layer tissues. Obtained results have practical significance.