OPTICAL PROPERTIES OF BIO TISSUES W/ STUDY USING FREQ DOMAIN PHOTON MIGRATION

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Laser Microbeam and Medical Program (LAMMP) facilities provide access to a multi-frequency, Frequency-Domain Photon Migration (FDPM) system which has proven its ability to extract optical properties, scattering and absorption, from a single-distance measurement on tissue-like phantoms and in vivo on human tissues. We, at EPFL (Dr. Depeursinge's group), have developed a Spatially-Resolved Photon Migration (SRPM) probe which allows local optical property measurements of biological tissues. Our current data analysis procedure is based upon comparisons of measurements to results of Monte Carlo numerical simulations. We propose to conduct combined experimental studies, using the LAMMP FDPM apparatus and clinical resources, to define an optimal photon migration system capable of deriving accurately the optical properties of complex, inhomogeneous tissues. This study involves 1) a quantitative determination of the volume of tissue interrogated in each technique; 2) an experi mental study on tissue-like layered solid phantoms in order to assess our ability to optically characterize each layer independently by using our combined setup; 3) the design of an optimal system (probe + inversion model) according to a thorough analysis of the potential advantages of frequency modulation at short distances (<J5Jmm); 4) clinical trials on breast, brain and gynecological human tissues, in vivo. We believe that LAMMP is able to provide us with a unique set of experimental and clinical facilities, which is optimal to complete the long-term goal of our research in this field, i.e. in vivo optical characterization of tissues as an aid to diagnostics and imaging. The outcome of this study and our experience in using LAMMP FDPM instrumentation will benefit our research efforts in photon migration and our contribution in the European Union-sponsored program Biomed-Near InfraRed Spectroscopy and Imaging (NIRSI).