The development and characterization of clinical intracavity ultrasonic applicators for hyperthermia

Cylindrical transducer elements, with sizes and operating frequencies favorable for applications in hyperthermia, are characterized. The effects of cutting these elements from whole cylinders down to halves and quarters (cuts parallel to axis), as well as the resonant frequency of operation (0.5, 1.0, and 1.6 MHz), were investigated. These results were used to develop clinical applicators consisting of multiple elements, one device for each frequency. These clinical applicators were operated with the controlled cooling of the tissue/applicator interface. The efficacy of these applicators were tested in vivo in the canine prostrate, rectal wall, and vaginal wall. The ability of these clinical applicators to provide controlled heating for different tumor geometries is discussed.<>