Dissertation > Excellent graduate degree dissertation topics show

Light Propagation in Layered Biological Tissue by Finite Element Method

Author: ChenJianLing
Tutor: XieShuSen；YangHongQin
School: Fujian Normal University
Course: Optics
Keywords: Finite Element Method Layered biological tissue Light propagation characteristics Diffuse optical tomography
CLC: Q63
Type: Master's thesis
Year: 2009
Downloads: 31
Quote: 0
Read: Download Dissertation

Abstract

Using the finite element method to solve the time-resolved diffusion equation, and analysis of the distribution of light in layered biological tissue. The finite element method is compared with Monte Carlo simulation main advantage lies in its calculation time is short and easy to deal with a complex organizational structure, and therefore its iteration of the inverse problem may be solved. In this paper, the finite element program to study the organization of the different moments of the semi-infinite tissue model and the three-tier organization model in vivo rate of energy flow distribution, the absorption coefficient, the reduced scattering coefficients of the tissue surface diffuse reflection light distribution organizations embedded in non-uniform The absorption and scattering of light distribution and energy flow rate of the tissue in vivo tissue surface diffuse reflectance distribution. Results: (1) Organization of the rate of energy flow in the body each time the distribution of observed can be very intuitive. (2) For the semi-infinite tissue model, different time position of the maximum of the photon energy where the tissue in different depths, and the for three organizational model, due to the influence of the characteristic parameters of the layers of optical, the maximum value of the different moments of photon energy may be located in the same depth in the tissue. (3) the absorption coefficient, reduced scattering coefficients of the diffuse reflectance of semi-infinite tissue surface light distribution and the first floor of the absorption coefficient of the first floor of the reduced scattering coefficients of diffuse reflection light distribution of the surface of the three organizations have an important impact. (4) semi-infinite tissue embedded in the third layer of the non-uniformity of the absorption and scattering, and three organizations embedded in a non-uniform absorption and scattering of light distribution and energy flow rate of the tissue in vivo distribution have a certain impact on the diffuse reflectance of the tissue surface. This study selected clinical application of laser incident power density, exposure time and beam size of important guiding role. The finite element method for solving the time-resolved diffusion equation, one aspect of the application is its inverse problem - diffuse optical tomography, this paper presents the theoretical basis for image reconstruction algorithm based on the Newton-Raphson method, by contrast select the optimal mesh resolution and the organizational structure of the flat plate-shaped, contains a substance absorption coefficient and the background absorption coefficient ratio of 2:1, and the radii of 5mm and 2.5mm imaging depth. The results: the size of the inclusions affect its imaging depth, the smaller the inclusions, the more difficult to accurately reconstruct the inclusions, the more shallow depth imaging. Inclusions radius R = Smm, better able to reconstruct the depth of the inclusion of about 13mm, but contains matter radius R = 2.0mm, better able to reconstruct the depth of the inclusion of about 10mm. This simulation to be carried out in the future experimental research has guiding significance.

Light Propagation in Layered Biological Tissue by Finite Element Method

Abstract

Related Dissertations