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

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

doi:10.1117/12.356788

15 July 1999 Tissue phantom studies on photon migration through fetal brain in utero using near-infrared spectroscopy

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

Proceedings Volume 3597, Optical Tomography and Spectroscopy of Tissue III; (1999) https://doi.org/10.1117/12.356788
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

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, .?a: 0.15 cm-1 & reduced scattering coefficient, ?s': 5.0 cm-1), an amniotic fluid sac (?a=0.02 cm-1, ?s= 0. 1 cm-1) and a maternal tissue layer (?a= 0.08 cm-1, ?s'= 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 (~20 mm)

Citation Download Citation

Gargi Vishnoi, Andreas H. Hielscher, Nirmala Ramanujam, Shoko Nioka, and Britton Chance "Tissue phantom studies on photon migration through fetal brain in utero using near-infrared spectroscopy", Proc. SPIE 3597, Optical Tomography and Spectroscopy of Tissue III, (15 July 1999); https://doi.org/10.1117/12.356788

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