Acoustic field prediction for a single planar continuous-wave source using an equivalent phased array method.

Phased array theory is combined with the Rayleigh-Sommerfeld diffraction integral to predict measured acoustic fields generated by a single-source ultrasonic transducer. The idea is to treat a single-source as a "phased array," which is composed of many small elements. The goal is to find the excitation source for the phased array, that is, the amplitude and phase for each array element, which produces an acoustic field similar to the experimentally measured field generated by the single-source transducer. A pressure field measured at a given plane parallel and close to the face of the transducer in degased water was used to calculate the excitation source of the equivalent phased array using an inverse technique. The excitation source of the equivalent phased array was then used to calculate the acoustic field from this measurement plane to the far field. It was demonstrated that this phased array approach accurately predicted the location of major grating lobes and the general distributions of the near and far pressure fields for four different transducers. This equivalent phased array method (EPAM) used to model a single-source transducer should be useful in both diagnostic and therapeutic ultrasound applications.

[1]  Kim C. Benjamin,et al.  Forward and backward projection of acoustic fields using FFT methods , 1981 .

[2]  P. Stepanishen.  The Time‐Dependent Force and Radiation Impedance on a Piston in a Rigid Infinite Planar Baffle , 1971 .

[3]  J Marini,et al.  Acoustical fields from rectangular ultrasonic transducers for non-destructive testing and medical diagnosis. , 1974, Ultrasonics.

[4]  C.A. Cain,et al.  Multiple-focus ultrasound phased-array pattern synthesis: optimal driving-signal distributions for hyperthermia , 1989, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[5]  A. Weyns,et al.  Radiation-field Calculations of Pulsed Ultrasonic Transducers .1. Planar Circular, Square and Annular Transducers , 1980 .

[6]  D. Hutchins,et al.  Transient pressure fields of PVDF transducers , 1987 .

[7]  Peter A. Lewin,et al.  Transducer characterization using the angular spectrum method , 1989 .

[8]  M. A. Breazeale,et al.  A diffraction beam field expressed as the superposition of Gaussian beams , 1988 .

[9]  J. Zemanek.  Beam Behavior within the Nearfield of a Vibrating Piston , 1971 .

[10]  Martin Greenspan,et al.  Piston radiator: Some extensions of the theory , 1979 .

[11]  Prediction of ultrasonic field propagation through layered media using the extended angular spectrum method. , 1994, Ultrasound in medicine & biology.

[12]  K. B. Ocheltree,et al.  Sound field calculation for rectangular sources , 1989, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  P. A. Puhach,et al.  Intensity fields of continuous‐wave axisymmetric transducers , 1987 .

[14]  A. Freedman.  Sound Field of a Rectangular Piston , 1960 .

[15]  J. C. Lockwood,et al.  High‐speed method for computing the exact solution for the pressure variations in the nearfield of a baffled piston , 1973 .

[16]  C. Cain,et al.  A spherical-section ultrasound phased array applicator for deep localized hyperthermia , 1991, IEEE Transactions on Biomedical Engineering.

[17]  L. V. Biesen,et al.  Parametric modeling and estimation of ultrasonic fields using a system identification technique , 1996 .

[18]  Julian D. Maynard,et al.  Numerical evaluation of the Rayleigh integral for planar radiators using the FFT , 1982 .

[19]  K Hynynen,et al.  A study of various parameters of spherically curved phased arrays for noninvasive ultrasound surgery. , 1996, Physics in medicine and biology.