DETERMINATION OF THE OPTICAL PROPERTIES OF MULTILAYERED PHANTOMS BY TIME-RESOLVED REFLECTANCE MEASUREMENTS

H. GARCIA; J. A. POMARICO.; D. I. IRIARTE; D. GROSENICK

Tandil

Congreso; 99° Reunión Nacional de Física; 2014

Asosiación Física Argentina

In Optics of Turbid Media the light propagation in substances which present strong scattering characteristics is studied. This is of particular interest for applications in Medical Diagnostics, because many biological tissues behave, from an optical point of view, like turbid media. The simplest approach for describing light propagation in tissue is the homogeneous model, i. e., the tissue is assumed to be a medium with constant absorption (μa ) and reduced scattering (μs ´) coefficients. However, in most cases, biological tissues have inhomogeneities, or they are intrinsically heterogeneous. In particular, systems like the human head can be thought as formed by several layers (scalp, skull, meninges, cerebrospinal fluid (CSF), gray matter, white matter) of different optical properties and, therefore, clearly differ from being a homogeneous medium. In this work we present results of experiments performed on phantoms (turbid media made in the lab, which emulate the optical behaviour of biological tissues) of two and three layers; in all cases the goal is to retrieve the optical properties of the deepest (liquid) layer through time-resolved reflectance measurements. This is of interest for developing applications such as recording of functional activation in the brain, measurement of tissue oxygenation, monitoring of glucose concentration in blood, etc. In these applications the characterization of deeper tissues (cortex) is of high relevance.