Abstract

In this dissertation, we have investigated light propagation in homogeneous and non-homogeneous tissue-like phantoms in both experimental and numerical methods. In experimental part, first of all, the tissue-like phantoms was constructed. Then, we fabricated an optical imaging system for data measurement. A NIR laser diode at 780nm was used as light source in this setup. The scattered light was detected by a very sensitive detector and the result was stored in computer.

In numerical part, a numerical code for solving diffusion equation which describes the light propagation manner in tissue has been written. We chose finite element method (FEM) for this simulation. The equation was solved for a stationary state and in 2-D cylindrical geometry with phantom radius. In this method, the cycle surface is divided into triangle meshes then the partial differential equation is transformed to linear algebraic equations which are solved by simple method like Gauss-Jordan.

In the next section, we compare the numerical and experimental results for testing the accuracy and precision validity of numerical code. Another purpose of this examination was to justify the optical parameters of constructed phantoms.

As final section, we inserted defect in normal phantoms to determine the numerical code sensitivity to depth and size of defect. Defect is a part of phantom with different optical properties that is as same as tumor in healthy tissue.

 

Keywords: diffuse optical imaging (DOI), light propagation in tissue, tissue-like phantom, finite element method (FEM)