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)

Date Published: 15 July 1999
PDF: 11 pages
Proc. SPIE 3597, Optical Tomography and Spectroscopy of Tissue III, (15 July 1999); doi: 10.1117/12.356788

Published in SPIE Proceedings Vol. 3597:
Optical Tomography and Spectroscopy of Tissue III
Britton Chance; Robert R. Alfano; Bruce J. Tromberg, Editor(s)