A Study of the Effect of Sensor Placement and Perfusion Pattern Variations on Thermal Tomography Solutions in Hyperthermia

The ability to predict complete temperature profiles from temperature measurements at a few locations is an important and difficult problem in cancer hyperthermia treatments; it is especially difficult because of a lack of knowledge of the tissue blood perfusion patterns and magnitudes. This paper describes an attempt to determine some of the characteristics of the problem so that it may be solved eventually. Results of simulation studies are presented for the solution of this combined state and parameter estimation problem using a steady-state technique previously developed. Particular attention is paid to the problems of estimating 1) the complete temperature field when the tissue perfusion pattern is unknown, and 2) the maximum and minimum tissue temperatures in situations where those temperatures have not been measured. The results indicate that this steady-state technique works well if the perfusion pattern is known, the pattern can be modeled accurately, and there is one temperature measurement for each unknown perfusion parameter. The applicability of the technique is seriously limited when any of these conditions are not met, since the predicted temperature field may then have significant errors.