Phase aberration correction for a linear array transducer using ultrasound radiation force and vibrometry optimization: Simulation study

Abstract

Diagnostic ultrasound images suffer from degradation due to tissues with sound speed inhomogeneities causing phase shifts of propagating waves. These phase shifts defocus the ultrasound beam, reducing spatial resolution and image contrast in the resulting image. We describe a phase aberration correction method that uses dynamic ultrasound radiation force to harmonically excite a medium using amplitude-modulated continuous wave ultrasound created by summing two ultrasound frequencies at f0=3.0 MHz and f0+Δf=3.0005 MHz. The phase of each element of a linear array transducer is sequentially adjusted to maximize the radiation force and obtain optimal focus of the ultrasound beam. The optimization is performed by monitoring the harmonic amplitude of the scatterer velocity in the desired focal region using Doppler techniques. Simulation results show the ability to regain a 3.0-MHz focused field after applying a phase screen with an rms time delay of 95.4 ns. The radiation force magnitude increased by 22 dB and the resolution of the field was regained. Simulation results show that the focus of the beam can be qualitatively and quantitatively improved with this method. [This study was supported in part by Grants EB002640 and EB002167 from the NIH.]