Wideband transducers for improved control of interstitial heating patterns

The feasibility of using multilayered transducers for variable frequency interstitial ultrasound thermal therapy was investigated. KLM calculations and experimental measurements evaluated the ability to transmit high intensity ultrasound at multiple frequencies from a single transducer. Heating simulations demonstrated the improved control over lesion depth with this design. Using a quarter wavelength PZT front "mismatching" layer, two transmission bands at 3.5 and 7.5 MHz were possible, resulting in the ability to control the lesion depth by a factor of 1.5 in tissue.