A dual-layer transducer array for 3-D rectilinear imaging

Abstract

Abstract2-D arrays for 3-D rectilinear imaging require very large element counts (16,000). The difficulties in fabricating and interconnecting 2-D arrays with a large number of elements (>5,000) have limited the development of suitable transducers for 3-D rectilinear imaging. In this paper, we propose an alternative solution to this problem by using a dual-layer transducer array design. This design consists of two perpendicular 1-D arrays for clinical 3-D imaging of targets near the transducer. These targets include the breast, carotid artery, and musculoskeletal system. This transducer design reduces the fabrication complexity and the channel count making 3-D rectilinear imaging more realizable. With this design, an effective N × N 2-D array can be developed using only N transmitters and N receivers. This benefit becomes very significant when N becomes greater than 128, for example. To demonstrate feasibility, we constructed a 4 × 4 cm prototype dual-layer array. The transmit array uses diced PZT-5H elements, and the receive array is a single sheet of undiced P [VDF-TrFE] copolymer. The receive elements are defined by the copper traces on the flexible interconnect circuit. The measured −6 dB fractional bandwidth was 80% with a center frequency of 4.8 MHz. At 5 MHz, the nearest neighbor crosstalk of the PZT array and PVDF array was −30.4 ± 3.1 dB and −28.8 ± 3.7 dB respectively. This dual-layer transducer was interfaced with an Ultrasonix Sonix RP system, and a synthetic aperture 3-D data set was acquired. We then performed off-line 3-D beamforming to obtain volumes of nylon wire targets. The theoretical lateral beamwidth was 0.52 mm compared to measured beamwidths of 0.65 mm and 0.67 mm in azimuth and elevation respectively. 3-D images of an 8 mm diameter anechoic cyst phantom were also acquired.

3-D Vector Flow Estimation With Row–Column-Addressed Arrays

“…Several versions and layouts of 2-D RC arrays have been presented for imaging purposes, for both piezoelectric arrays [25], [26] and Capacitive Micromachined Ultrasonic Transducers (CMUTs) [27]- [29]. However, the potential of estimating blood flow with RC arrays has only recently been reported in the literature [30].…”

Crossed-array transducer for real-time 3D imaging

“…Imaging using a crossed-array geometry, also referred to as a row-column array in literature, has been concurrently studied by other research groups. Implementations have included CMUT arrays [8], [9], multiple stacked transducers [10], and piezocomposite based row-column arrays [11]. This research pursues similar objectives, but establishes some novel solutions to address the unique requirements imposed by the crossedarray geometry.…”

Beamforming of sound from two-dimensional arrays using spatial matched filters

“…As another possible solution to the sparse array problem, several researchers previously proposed a row-column addressing approach which minimizes the interconnect and electrical impedance challenges. [10][11][12] In this approach, an N Â N 2D array requiring N Ù 2 separate elements can be replaced by an array of comparable size but requires only 2N elements. This represents a substantial savings when N is on the order of 128 to 256.…”