Two-dimensional arrays for medical ultrasound

The design, fabrication and evaluation of two-dimensional transducer arrays are described for medical ultrasound imaging. A 4×32, 2.8-MHz array was developed to use new signal processing techniques for improved B-scan imaging including elevation focusing, phase correction and synthetic aperture imaging. Laboratory measurements from typical array elements showed 50 Ω insertion loss of -56 dB, -6 dB fractional bandwidth of 43%, interelement cross-talk of -19 dB, and -6 dB pulse-echo angular response of 62°. Several 16×16 arrays have also been developed for high-speed volumetric imaging. These include 96 transmit elements and 32 receive channels. With a λ/4 matching layer, laboratory measurements show a 50-Ω insertion loss of -72 dB, -6 dB fractional bandwidth of 63%, interelement cross-talk of -29 dB, and -6 dB angular response of 25°. In vivo cardiac, abdominal, and obstetric B-scans with elevation focusing have been obtained, as well as high-speed C-scans, with these 2-D arrays