The use of optical fluence rate distribution for the differentiation of biological tissues

Diffuse optical imaging is a recent, safe, non-invasive, functional, and very promising medical imaging technique that employs near infrared light to characterize biological tissue. Absorption and scattering properties of biological tissues give very important information about physiological changes associated with vasculature, cellularity, and oxygen consumption in normal and/or diseased tissue. Obtaining the optical fluence rate distribution is important when constructing the image in diffuse imaging. In this work, the significance of using the fluence rate distribution for differentiating tissue types was investigated. An experimental setup for measuring spatially-resolved steady state diffuse reflectance spectra of breast chicken skin at 660nm laser irradiation was implemented. The measured values were then used to predict the optical parameters of the samples using a combination of a modified Kubelka-Munk method and Bouguer-Beer-Lambert law. These parameters were used with a finite element model to solve the radiative transfer equation to obtain the fluence rate at the sample boundary. The results revealed that the fluence rate distribution of a 660nm laser is significant in differentiating biological tissues.