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Proceedings Paper

Dual-frequency super harmonic imaging piezoelectric transducers for transrectal ultrasound
Author(s): Jinwook Kim; Sibo Li; Sandeep Kasoji; Paul A. Dayton; Xiaoning Jiang
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Paper Abstract

In this paper, a 2/14 MHz dual-frequency single-element transducer and a 2/22 MHz sub-array (16/48-elements linear array) transducer were developed for contrast enhanced super-harmonic ultrasound imaging of prostate cancer with the low frequency ultrasound transducer as a transmitter for contrast agent (microbubble) excitation and the high frequency transducer as a receiver for detection of nonlinear responses from microbubbles. The 1-3 piezoelectric composite was used as active materials of the single-element transducers due to its low acoustic impedance and high coupling factor. A high dielectric constant PZT ceramic was used for the sub-array transducer due to its high dielectric property induced relatively low electrical impedance. The possible resonance modes of the active elements were estimated using finite element analysis (FEA). The pulse-echo response, peak-negative pressure and bubble response were tested, followed by in vitro contrast imaging tests using a graphite-gelatin tissue-mimicking phantom. The single-element dual frequency transducer (8 × 4 × 2 mm3) showed a -6 dB fractional bandwidth of 56.5% for the transmitter, and 41.8% for the receiver. A 2 MHz-transmitter (730 μm pitch and 6.5 mm elevation aperture) and a 22 MHz-receiver (240 μm pitch and 1.5 mm aperture) of the sub-array transducer exhibited -6 dB fractional bandwidth of 51.0% and 40.2%, respectively. The peak negative pressure at the far field was about -1.3 MPa with 200 Vpp, 1-cycle 2 MHz burst, which is high enough to excite microbubbles for nonlinear responses. The 7th harmonic responses from micro bubbles were successfully detected in the phantom imaging test showing a contrast-to-tissue ratio (CTR) of 16 dB.

Paper Details

Date Published: 23 March 2015
PDF: 10 pages
Proc. SPIE 9438, Health Monitoring of Structural and Biological Systems 2015, 943823 (23 March 2015); doi: 10.1117/12.2084459
Show Author Affiliations
Jinwook Kim, North Carolina State Univ. (United States)
Sibo Li, North Carolina State Univ. (United States)
Sandeep Kasoji, Joint Dept. of Biomedical Engineering, Univ. of North Carolina and North Carolina State Univ. (United States)
Paul A. Dayton, Joint Dept. of Biomedical Engineering, Univ. of North Carolina and North Carolina State Univ. (United States)
Xiaoning Jiang, North Carolina State Univ. (United States)


Published in SPIE Proceedings Vol. 9438:
Health Monitoring of Structural and Biological Systems 2015
Tribikram Kundu, Editor(s)

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