Ultrasonic hyperthermia system for tumor irradiation

A laboratory ultrasonic exposure system has been developed to investigate practical energy regimes and equipment that will provide a modality for producing irreversible ultrastructural and biochemical changes to animal tumors in vivo. Electric energy is made available over a wide range of power levels and frequencies. This energy is converted to sonic pressure energy by piezoelectric element transducers. The transducer is an applicator that transmits a collimated or focused energy field to irradiate the tumor target area. That energy absorbed by the tumor gives rise to a spatial temperature distribution. Using their primary laboratory delivery system, the authors treated subcutaneous tumors in rats at controlled levels of energy and temperature. The results indicate that there are thresholds of applied energy and base temperatures above which substantial tumor damage can be expected. Histological examination supported by biochemical analysis reveals irreversible ultrastructural and chemical changes.