FREQUENCY-DOMAIN FLUORESCENT DIFFUSION TOMOGRAPHY - A FINITE-ELEMENT-BASED ALGORITHM AND SIMULATIONS

We present a finite-element-based algorithm for reconstruction of fluo rescence lifetime and yield in turbid media, using frequency-domain da ta. The algorithm is based on a set of coupled diffusion equations tha t describe the propagation of both excitation and fluorescent emission light in multiply scattering media. Centered on Newton's iterative me thod, we implemented our algorithm by using a synthesized scheme of Ma rquardt and Tikhonov regularizations. A low-pass spatial filter is als o incorporated into the algorithm for enhancing image reconstruction. Simulation studies using both noise-free and noisy data have been perf ormed with the nonzero photon density boundary conditions. Our results suggest that quantitative images can be produced in terms of fluoresc ent Lifetime and yield values and location, size, and shape of heterog eneities within a circular background region. (C) 1998 Optical Society of America.