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Proceedings Paper

High-frequency transducers for ultrasonic backscatter microscopy
Author(s): Patrick D. Lopath; Richard J. Meyer; Shameer Ayyappan; Kevin A. Snook; Timothy A. Ritter; K. Kirk Shung
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Paper Abstract

Very high frequency (VHF) ultrasound (> 20 MHz) has recently gained much attention as an effective non-invasive means to diagnose ocular and dermatological lesions. These ultrasonic backscatter microscopy systems have advanced rapidly with the electronics industry; however the VHF transducers are often the limiting factor in the overall image quality. This overview examines a number of the issues facing the high frequency transducer designer, including active material selection, passive components, acoustic and electrical matching and accurate characterization. Modified lead titanate was used as an active material to examine the use of a transmission line transformer to improve the electrical match between 25 and 40 MHz transducers and 50 (Omega) electronics. At 40 MHz, the transformer was shown to improve response only modestly, increasing bandwidth a few percent and insertion loss a few dB. At 25 MHz, -6 dB bandwidth improved almost 60%; however, peak sensitivity increased only 1 dB. PZT fiber composites were investigated to determine the effect of various volume fractions and passive backings on high frequency response. Parylene C was shown to be an effective matching layer for these composites, improving bandwidth of the 30% volume fraction transducers by 20% and sensitivity by 5 dB. Finally, a test setup, taking advantage of state of the art in linear positioners, is presented, addressing the issues pertinent to high frequency transducer characterization.

Paper Details

Date Published: 21 June 1999
PDF: 11 pages
Proc. SPIE 3664, Medical Imaging 1999: Ultrasonic Transducer Engineering, (21 June 1999); doi: 10.1117/12.350686
Show Author Affiliations
Patrick D. Lopath, NIH Resource Ctr. for Medical Ultrasonic Transducer Technology/The Pennsylvania State Univ (United States)
Richard J. Meyer, NIH Resource Ctr. for Medical Ultrasonic Transducer TechnologyThe Pennsylvania State Univ. (United States)
Shameer Ayyappan, NIH Resource Ctr. for Medical Ultrasonic Transducer Technology/The Pennsylvania State Univ (United States)
Kevin A. Snook, NIH Resource Ctr. for Medical Ultrasonic Transducer Technology/The Pennsylvania State Univ (United States)
Timothy A. Ritter, NIH Resource Ctr. for Medical Ultrasonic Transducer Technology/The Pennsylvania State Univ (United States)
K. Kirk Shung, NIH Resource Ctr. for Medical Ultrasonic Transducer Technology/The Pennsylvania State Univ (United States)


Published in SPIE Proceedings Vol. 3664:
Medical Imaging 1999: Ultrasonic Transducer Engineering
K. Kirk Shung, Editor(s)

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