Abstract: Implant strategies using multiple catheter-cooled interstitial ultrasound applicator were investigated for the ability to conform temperature distributions and thermal coagulation within a targeted tissue volume for either hyperthermia or high temperature thermal therapy in the prostate. Multi- element ultrasound applicators were fabricated using cylindrical piezoceramic transducers sectored to 220 degrees to provide angular directional heating, and in non-directional configurations. The applicators were designed to be inserted into standard 13 or 14 gage brachytherapy catheters integrated with water-cooling. Measurements of acoustic power output, and beam profile distributions were obtained in degassed water. Thermal lesions were formed in fresh in vitro beef muscle, and in vivo pig thigh muscle. Axial and radial temperature distributions were monitored using multi-junction thermocouple probes. Thermal lesions measuring 4 cm diameter were produced in vitro within 4 minutes of heating with 5 W applied electrical power delivered to 6 applicators with an angular spacing of 60 degrees. In vivo thermal lesions generated in pig thigh muscle using only 4 directional applicators were confined to a target volume of 3 cm diameter by 3 cm long. Temperatures measured in the center of the target volume reached 85 degrees Celsius during heating, while temperatures outside the target volume remained below 45 degrees Celsius. Results from these studies indicated the ability to control thermal coagulation within the targeted tissue while protecting surrounding tissue from thermal damage. !13
展开▼
