Tissue phantom studies on photon migration through fetal brain in-utero using near infra-red spectroscopy

Gargi Vishnoi, Andreas H. Hielscher, Nirmala Ramanujam, Shoko Nioka, Britton Chance

    Research output: Contribution to journalConference articlepeer-review

    Abstract

    We present tissue phantom experimental results and theoretical simulations to study photon migration through the fetal head in-utero. A continuous-wave (CW), dual wavelength (760 & 850 nm) spectrometer was developed and employed for the experiments at a source-detector separation of 10 cm. Theoretical simulations were performed using time-independent, finite-difference, discrete-ordinate, radiative-transport and diffusion equations. Two phantom geometries viz. circular and rectangular were considered. The tissue phantom incorporates a fetal head (absorption coefficient, μa: 0.15 cm-1 & reduced scattering coefficient, μs': 5.0 cm-1), an amniotic fluid sac (μa=0.02 cm-1, μs'= 0.1 cm-1) and a maternal tissue layer (μa= 0.08 cm-1, μs'= 5.0 cm-1). Photon fluence from the tissue phantom was quantified as a function of fetal head depth and its position relative to probe placement. Experimental results obtained with spectrometer were found to be congruent with theoretical results and clinical investigations. The results indicate that photon fluence decreases with increase in fetal head depth for circular geometry, while it increases with increase in fetal head depth for rectangular geometry. This paradoxical result observed may be attributed to the effect of amniotic fluid in the light path. Photon fluence is sensitive for fetal head depths within 40 mm. This is well within the fetal head depths expected in near-term patients (approx. 20 mm).

    Original languageEnglish (US)
    Pages (from-to)650-660
    Number of pages11
    JournalProceedings of SPIE - The International Society for Optical Engineering
    Volume3597
    StatePublished - 1999
    EventProceedings of the 1999 Optical Tomography and Spectroscopy of Tissue III - San Jose, CA, USA
    Duration: Jan 24 1999Jan 28 1999

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Computer Science Applications
    • Applied Mathematics
    • Electrical and Electronic Engineering

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