FEA computations of heating patterns from power measurements for interstitial applicators

Pattern of power deposition from interstitial devices governs in principle heating pattern. In reality the heating pattern will also depend on placement of applicators with respect to the surface at ambient temperature and also on locally different properties of the heated medium. This presentation gives results of computations of temperature distribution in heating with four ultrasound or microwave applicators. The computations are based on a measured power deposition front the applicators. Local microstructures of the medium are represented as heat sinks. We show that the ultrasound devices produce more uniform and deeper heating with the same length of radiating parts. Heating patterns in 3-D from our computations lack the symmetry of the measured power, the effect especially dramatic for the microwave applicators. The type of computations presented here gives details of heating pattern unavailable from power measurements in phantoms. We conclude that the computations should form integral part of verification of an instrumentation performance