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

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Transducer Design

Background:

• Three-dimensional (3-D) rectilinear ultrasound imaging requires a large number of elements (16,000-65,000) in 2-D arrays.
• Fabrication and interconnection challenges for large 2-D arrays (>5,000 elements) have hindered the development of suitable transducers for 3-D rectilinear imaging.

Purpose of the Study:

• To propose a dual-layer transducer array design as an alternative solution for 3-D rectilinear imaging.
• To reduce fabrication complexity and channel count for more feasible 3-D rectilinear imaging.
• To enable clinical 3-D imaging of superficial targets like the breast, carotid artery, and musculoskeletal system.

Main Methods:

• Developed a dual-layer transducer with two perpendicular 1-D arrays (N transmitters and N receivers) to emulate an N x N 2-D array.
• Constructed a 4 x 4 cm prototype using diced PZT-5H elements for transmission and an undiced P[VDF-TrFE] copolymer sheet for reception.
• Interfaced the transducer with an Ultrasonix Sonix RP system for synthetic aperture 3-D data acquisition and offline 3-D beamforming.

Main Results:

• Achieved a measured -6 dB fractional bandwidth of 80% at a 4.8 MHz center frequency.
• Nearest neighbor crosstalk was -30.4 +/- 3.1 dB (PZT) and -28.8 +/- 3.7 dB (PVDF) at 5 MHz.
• Obtained measured lateral beamwidths of 0.65 mm (azimuth) and 0.67 mm (elevation), close to the theoretical 0.52 mm, and acquired 3-D images of a cyst phantom.

Conclusions:

• The dual-layer transducer array design significantly simplifies 3-D rectilinear ultrasound transducer fabrication and reduces channel requirements.
• This approach makes 3-D rectilinear imaging more achievable, particularly for superficial anatomical targets.
• The prototype demonstrated excellent performance, validating the feasibility of this innovative transducer design for clinical applications.