IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control2015: V62,p350 ; DOI:TUFFC.2014.006800
Field characterization methods using a scattering target in the absence of a point-like receiver have been well described in which scattering is recorded by a relatively large receiver located outside the field of measurement. Unfortunately, such methods are prone to artifacts due to averaging across the receiver surface. To avoid this problem while simultaneously increasing the gain of a received signal, the present study introduces a binary plate lens designed to focus spherically-spreading waves onto a planar region having a nearly-uniform phase proportional to that of the target location. The lens is similar to a zone plate, but modified to produce a bi-convex-like behavior, such that it focuses both planar and spherically spreading waves. A measurement device suitable for characterizing narrowband ultrasound signals in air is designed around this lens by coupling it to a target and planar receiver. A prototype device is constructed and used to characterize the field of a highly-focused 400 kHz air transducer along 2 radial lines. Comparison of the measurements with numeric predictions formed from nonlinear acoustic simulation showed good relative pressure correlation, with mean differences of 10% and 12% over center 3dB FWHM drop and 12% and 17% over 6dB.
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Clinic Ultrasound Laboratory (クレメント超音波研究室)
Cleveland Clinic (クリーブランド・クリニック),
Lerner Research Institute
Case Western Reserve University
© 2014
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Clement GT, Nomura H, Adachi H, Kamakura T, Feasibility of non-contact ultrasound for medical imaging, Physics in Medicine and Biology 2014; 58: 6263-6278
Tang SC, Jolesz FA, Clement GT. A Wireless Batteryless Implantable Ultrasonic Pulser-Receiver. IEEE Trans Ultrason Ferroelectr Freq Control 2011;58:1211-21.
Paltiel HJ, Padua HM, Gargollo PC, Cannon GM Jr, Alomari AI, Yu R, Clement GT. Volumetric ultrasound imaging of tissue perfusion: preliminary results in a rabbit model... Phys Med Biol 2011;56:2183-97.
McDannold N, Clement GT, Black P, Jolesz F, Hynynen K. Focused ultrasound surgery of brain tumors: Initial findings in three patients. Neurosurgery 2010;66:323-32; discussion 332.
Clement GT, Hynynen K. A non-invasive method for focusing ultrasound through the human skull. Phys Med Biol 2002;47(8):1219-36.