Transmission mode adaptive beamforming for planar phased arrays and its application to 3D ultrasonic transcranial imaging

Kiyanoosh Shapoori; Jeffrey Sadler; Adrian Wydra; Eugene Malyarenko; Anthony Sinclair; Roman G. Maev

doi:10.1117/12.2006505

29 March 2013 Transmission mode adaptive beamforming for planar phased arrays and its application to 3D ultrasonic transcranial imaging

Kiyanoosh Shapoori, Jeffrey Sadler, Adrian Wydra, Eugene Malyarenko, Anthony Sinclair, Roman G. Maev

Author Affiliations +

Proceedings Volume 8675, Medical Imaging 2013: Ultrasonic Imaging, Tomography, and Therapy; 86750P (2013) https://doi.org/10.1117/12.2006505
Event: SPIE Medical Imaging, 2013, Lake Buena Vista (Orlando Area), Florida, United States

Abstract

A new adaptive beamforming method for accurately focusing ultrasound behind highly scattering layers of human skull and its application to 3D transcranial imaging via small-aperture planar phased arrays are reported. Due to its undulating, inhomogeneous, porous, and highly attenuative structure, human skull bone severely distorts ultrasonic beams produced by conventional focusing methods in both imaging and therapeutic applications. Strong acoustical mismatch between the skull and brain tissues, in addition to the skull's undulating topology across the active area of a planar ultrasonic probe, could cause multiple reflections and unpredictable refraction during beamforming and imaging processes. Such effects could significantly deflect the probe's beam from the intended focal point. Presented here is a theoretical basis and simulation results of an adaptive beamforming method that compensates for the latter effects in transmission mode, accompanied by experimental verification. The probe is a custom-designed 2 MHz, 256-element matrix array with 0.45 mm element size and 0.1mm kerf. Through its small footprint, it is possible to accurately measure the profile of the skull segment in contact with the probe and feed the results into our ray tracing program. The latter calculates the new time delay patterns adapted to the geometrical and acoustical properties of the skull phantom segment in contact with the probe. The time delay patterns correct for the refraction at the skull-brain boundary and bring the distorted beam back to its intended focus. The algorithms were implemented on the ultrasound open-platform ULA-OP (developed at the University of Florence).

Citation Download Citation

Kiyanoosh Shapoori, Jeffrey Sadler, Adrian Wydra, Eugene Malyarenko, Anthony Sinclair, and Roman G. Maev "Transmission mode adaptive beamforming for planar phased arrays and its application to 3D ultrasonic transcranial imaging", Proc. SPIE 8675, Medical Imaging 2013: Ultrasonic Imaging, Tomography, and Therapy, 86750P (29 March 2013); https://doi.org/10.1117/12.2006505

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