The design of ultrasound applicators for interstitial hyperthermia

Theoretical and experimental methods were used to evaluate two new design strategies of interstitial ultrasound applicators for hyperthermia. The basic schema consists of a multielement array of tubular piezoceramic radiators, each with separate RF power control. Computer simulation programs were developed to calculate the acoustic fields and resultant thermal distributions of these applicators when embedded in tissue. A quantitative analysis was undertaken to determine heating performance as a function of implant spacing, blood perfusion, catheter material, temperature of circulating coupling medium, frequency, and acoustic power output. Prototype multielement applicators were constructed and characterized in terms of acoustic pressure distributions and acoustic power output capabilities