AN IMPROVED BOLUS CONFIGURATION FOR COMMERCIAL MULTIELEMENT ULTRASOUND AND MICROWAVE HYPERTHERMIA SYSTEMS

A simple modification is presented for two commercially available hype rthermia applicators which dramatically improves the regulation and dy namic control of the temperature at the bolus/tissue interface. This a lteration requires the addition of a variable speed pump, bubble trap, simple heat exchanger, and a few minor changes to the existing system . With this modified design, the water within the bolus is directly ci rculated and temperature controlled. The convective nature of the circ ulating system ensures uniform temperature throughout the extended bol us and increases the thermal energy transfer at the bolus/tissue inter face. This modification also provides significantly improved flexibili ty in controlling the treatment temperature distributions since the bo lus/tissue interface temperature can now be dynamically varied during a treatment, in addition to adjusting the applicator power output and frequency.