title: 7.5 MHz dual-layer transducer array for 3-D rectilinear imaging.
abstract: The difficulties associated with fabrication and interconnection have limited the development of 2-D ultrasound transducer arrays with a large number ofelements (>5000). In previous work, we described a 5 MHz center frequency PZT-P[VDF-TrFE] dual-layer transducer that used two perpendicular 1-D arrays for 3-D rectilinear imaging. This design substantially reduces the channel count as well as fabrication complexity, which makes 3-D imaging more realizable. Higher frequencies (>5 MHz) are more commonly used in clinical applications or imaging targets near transducers, such as the breast, carotid and musculoskeletal tissue. In this paper, we present a 7.5 MHz dual-layer transducer array for 3-D rectilinear imaging. A modified acoustic stack model was designed and fabricated. PZT elements were sub-diced to eliminate lateral coupling. This sub-dicing process made the PZT into a 2-2 composite material, which could help improve transducer sensitivity and bandwidth. Full synthetic-aperture 3-D data sets were acquired by interfacing the transducer with a Verasonics data-acquisition system (VDAS). Offline 3-D beamforming was then performed to obtain volumes of a multiwire phantom and a cyst phantom. The generalized coherence factor (GCF) was applied to improve the contrast of cyst images. The measured -6 dB fractional bandwidth of the transducer was 71% with a center frequency of 7.5 MHz. The measured lateral beamwidths were 0.521 mm and 0.482 mm in azimuth and elevation, respectively, compared with a simulated beamwidth of 0.43 mm.
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA. yuling@usc.edu
authors.forename: Yuling
authors.initials: Y
authors.lastname: Chen
authors.forename: Man
authors.initials: M
authors.lastname: Nguyen
authors.forename: Jesse T
authors.initials: JT
authors.lastname: Yen
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D019047:Phantoms, Imaging; D011108:Polymers; D012815:Signal Processing, Computer-Assisted; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*
chemical_list: D011108:Polymers