Determinação das propriedades dinâmicas em meios turvos usando espectroscopia de correlação de difusão: aplicações ao tecido biológico

Author(s)

Rodrigo Menezes Forti

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2015-06-04

Examining board members

Rickson Coelho Mesquita; José Antonio Brum; Fernando Fernandes Paiva

• Advisor: Rickson Coelho Mesquita

Abstract

Spectroscopic techniques based on diffuse optics are essential for determination of the optical and dynamical properties of turbid media, in which scattering predominates over absorption. Under these conditions, light propagates spherically in the medium, in an approximate diffusive regimen. Scattered light can thus be detected at the same plane of incidence, and its detection can provide information both on the optical and dynamical properties of the medium. Diffuse optical techniques are particularly useful to study the properties of biological tissue, since it behaves like a turbid medium in the near infrared region. Because diffuse optics is a relatively novel experimental technique, not much is known regarding the propagation of light in media with different geometries, particularly with relation to the dynamical properties of the medium. This project proposes a combined theoretical and experimental study of light propagation in semi-infinite and two-layered turbid media, focusing on the dynamical properties of the medium with a diffuse optical technique called diffuse correlation spectroscopy (DCS). More specifically, this project employed the semi-infinite and the two-layer geometries, testing them using Monte Carlo simulations and controlled enviroments. It was shown that by using a two-layer geometry, instead of the semi-infinite geometry, as routinely done in the literature, it is possible to significantly improve the accuracy of the recovered dynamical properties. The geometries tested in this work represent more accurate approximations for muscle and brain structures, for example, and therefore could depict different situations encountered in problems in the fields of Biology and Medicine. Last, the system was also tested in healthy subjects. The results obtained in this project have direct application in the above-cited fields, and may significantly contribute to the development of experimental techniques for diagnosis and/or monitoring of the brain and muscle in the clinic (AU)

• FAPESP's process: 12/25363-6 - Determination of the dynamical properties in turbid media using diffuse correlation spectroscopy: applications to biological tissue
• Grantee: Rodrigo Menezes Forti
• Support Opportunities: Scholarships in Brazil - Master