Determination of the optical properties of multilayered phantoms by time-resolved reflectance measurements

GARCÍA, H.; POMARICO, J. A.; IRIARTE, D. I.; GROSENICK, D.

Tandil

Congreso; 99° Reunión Nacional de Física; 2014

In Optics of Turbid Media the light propagation in substances which present strong scattering characteristics is studied. This is ofparticular interest for applications in Medical Diagnostics, because many biological tissues behave, from an optical point of view, liketurbid media. The simplest approach for describing light propagation in tissue is the homogeneous model, i. e., the tissue is assumed tobe a medium with constant absorption (μ a ) and reduced scattering (μ s ') coefficients. However, in most cases, biological tissues haveinhomogeneities, or they are intrinsically heterogeneous. In particular, systems like the human head can be thought as formed byseveral 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 (turbidmedia made in the lab, which emulate the optical behaviour of biological tissues) of two and three layers; in all cases the goal is toretrieve the optical properties of the deepest (liquid) layer through time-resolved reflectance measurements. This is of interest fordeveloping applications such as recording of functional activation in the brain, measurement of tissue oxygenation, monitoring ofglucose concentration in blood, etc. In these applications the characterization of deeper tissues (cortex) is of high relevance.