TEMPERATURE-FIELD ESTIMATION USING ELECTRICAL-IMPEDANCE PROFILING METHODS .1. RECONSTRUCTION ALGORITHM AND SIMULATED RESULTS

Algorithmic methods for estimating complete temperature fields during hyperthermia treatments based on surface and internal electrical measu rements are presented. The techniques utilized draw upon impedance ima ging concepts, but rather than limit the measurements to positions on the body surface, internal impedance recording sites are allowed. Theo retical simulations show that this strategy improves the reconstructed image in the target region when either internal measurement locations are added to a given number of external recording sites or some exter nal measurement locations are replaced by internal recording positions . The algorithms developed are tested on a set of problems with increa sing levels of complexity. The culmination of these investigations is a complete simulation of a hyperthermia treatment and reconstruction o f a thermal image for a body cross-section of an actual cancer patient . The results of this work suggest that the surface plus internal meas urement approach holds some promise as a method for estimating tempera ture distributions during hyperthermia treatments. However, the simula tions while promising are idealizations in that they are two-dimension al with modest levels of additive noise. In a companion paper, we expl ore the viability of this approach in several laboratory phantom exper iments which include both static and heat-induced transient electrical property profiles.