Studies of The Optical Characteristics of Skin Tissue Using Monte Carlo Simulation
| Autor: | Yi-Sheong Chou, 周義雄 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 Some pathological conditions of tissue would cause changes in the optical properties tissue. Such changes allow us to detect tissue condition through optical measurements of tissue light transmission and reflectance. This approach requires a better understanding of how light propagates and distributes inside a biological tissue. In order in tissue, the distribution of light intensity has to be known. Since any instrument inserted into tissue to quantify the light energy and its distribution in tissue will also affect the light intensity distribution, the intensity distribution can not be directly measured. Therefore, a mathematical model has to be used to estimate the light intensity distribution in tissue. In this study, a Monte Carlo simulation of light transport in a two-layered tissue model has been developed for studying: (1) the skin near-infrared reflectance spectrum, (2) the light intensity distribution in biological tissue, and (3) the light path in biological tissue. The Monte Carlo method has the advantage of including the anisotropy scattering factor into the simulation. This makes the simulation result much close to the real condition, especially in the near-infrared region where light has a strong forward scattering property in biological tissue. Complicate boundary conditions can also be easily handle in Monte Carlo simulations. The near-infrared reflectance spectrum of skin between 900 nm and 1300 nm was simulated. By comparing with the measurement in human subjects, we found that the simulated results are similar to the measurements in both the shape and magnitude of spectra. Simulation results also tell us the relationship between the tissue optical coefficients and the light reflectance intensity. The simulated light intensity distribution in biological tissue was also compared to the images taken with light injected close to the front surface of tissue. Simulation was also carried out to help the design of the measuring probe of Laser Doppler flowmetry. The light penetration depth and traveling region depend on the distance between the transmitting and receiving optical fiber tips. The simulation tells us how to choose the right design of the probe geometry. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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