Multi-element transducers for conformal transurethral thermal therapy

Transurethral thermal therapy of the prostate using ultrasound may be used to create a thermal lesion that matches a target volume of tissue while sparing surrounding structures. To produce multiple-element ultrasound transducers for this purpose, a fabrication method of sub-dicing one continuous piece of piezoceramic to isolate individual elements was employed. Finite element modeling was used to determine the required dicing cut width and depth for adequate inter-element isolation. Experimental acoustic measurements were used to evaluate device efficiency and power stability over a range of element widths (2 to 4 mm) and lengths (3 to 30 mm). Efficiencies of 50% or higher and power output suitable for thermal therapy were achievable for all element sizes tested. This method of fabrication and testing is being utilized for evaluation of prototype devices designed for prostate thermal therapy.