Estimation of the backattenuation coefficient of light in biological medium by computer modeling

The laser irradiation (630 nm) of cancerous cells produces singlet oxygen in the presence of a photochemical agent. Singlet oxygen is responsible for tumor necrosis. Light attenuation in biological tissues is a function of light scattering and absorption phenomenons. The determination of the light attenuation in tissues is of vital importance in the determination of an optimal light dosimetry. Here, the authors developed a model for light propagation in biological tissues and an optical fiber sensor for the measurement of the backattenuation coefficient Σ_ba. The Σ_ba coefficient permits the estimation of the absorbed dose and so the optimization of the therapeutic efficiency. Simulation results were then compared with those measured during previous experiments. Qualitative comparison between simulation and experimental results allows the authors to confirm that propagation model and simulated sensor reflects the real phenomenon