<title>Influence of piezoceramic composition, pitch, and layout on the performances of sparse 2D array transducers for medical imaging</title>

Abstract

Two dimensinal (2D) array transducers have become of great interest in the last few years, in view of the possibility of real time volumetric ultrasonic imaging. However, due to low signal to noise ratio and to the limited number of channels on available imaging systems, both sensitivity and resolution of such array are lower than those of 1D arrays. First, new high dielectric permittivity PNNZT piezoceramics are characterized and compared to classical PZT. 2D array elements are then manufactured and their experimental performances are compared. PNNZT allows an increase in element pulse echo sensitivity around 6 dB as compared to PZT array elements. The effects of the pitch and layout on the sparse array radiation pattern for several steering angles are investigated. Pseudo-random layouts are shown to have satisfactory acoustic noise level as compared to periodic layouts (vernier). Moreover, such configurations allow the pitch to be increased slightly over the classical half wavelength phased-array value, thus increasing the active area (i.e. sensitivity). Optimized array configuration leads to an increase in acoustic sensitivity of at least 6 dB and a decrease of acoustic noise level around 10 dB.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.