ASA 127th Meeting M.I.T. 1994 June 6-10

4pEA8. Optimization of medical imaging transducers by a piezoelectric computer-aided design system.

Reinhard Lerch

Dept. of Messtechnik, Univ. of Linz, Altenberger Strasse 69, A-4040 Linz, Austria

Hans T. Kaarmann

Siemens Med. Systems, Inc., Issaquah, WA 98027

The capabilities of a software package developed for the computer-aided design (CAD) of electroacoustic transducers operating under fluid load are reported. The simulation capabilities are mainly based on a combined finite element boundary element technique. The package contains modules for the geometric modeling, pre- and postprocessing tools for supporting the simulation, the numerical analysis software, and an optimization module. Main criteria for the optimization of ultrasonic phased array antennas used for diagnostic imaging are (i) high efficiency in transmit and receive mode (noise), (ii) short ultrasound pulse length (sharpness), (iii) broad radiation pattern (wide field of view). The CAD package was utilized for the determination of the optimal design parameters, such as the geometry of the transducer elements, the characteristics of applied piezoactive and non-piezoactive materials, and features of the electrical interface networks. In practical applications, the design software revealed to be superior to conventional design methods, especially in the final optimization of parameters, such as the refinement of transducer geometry. Furthermore, the understanding of physical phenomena, such as the crosstalk between array elements, is mainly enhanced by utilizing these computer simulations. The improvements in respect to the above optimization criteria obtained by the computer support have been experimentally verified.