OPTICAL-IMAGE RECONSTRUCTION USING FREQUENCY-DOMAIN DATA - SIMULATIONS AND EXPERIMENTS

Optical image reconstruction in a heterogeneous turbid medium with the use of frequency-domain measurements is investigated in detail. A fin ite-element reconstruction algorithm for optical data based on a diffu sion equation approximation is presented and confirmed by a series of simulations and experiments using phantoms having optical properties i n the range of those expected for tissues. Simultaneous reconstruction of absorption and scattering coefficients is achieved both theoretica lly and experimentally. Images with different target locations and con trast levels between target and background are also successfully recov ered. All reconstructed images from both simulated and experimental da ta are derived directly from absolute optical data in which no differe ntial measurement scheme is used. Results from the use of simulated an d measured data suggest that quantitative images can be produced in te rms of absorption and scattering coefficient values and location, size , and shape of heterogeneities within a circular background region ove r a range of contrast levels. Further, the effects of modulation frequ ency are found to be relatively modest, although boundary conditions a ppear to be important factors. (C) 1996 Optical Society of America