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Mohamed Ghanem

Research Associate

Email

mghanem@apl.uw.edu

Education

Ph.D. Astronautics & Aeronautics Engineering, University of Washington-Seattle , 2019

M.S. Structural Engineering, Aeronautics, & Astronautics Engineering, University of Washington-Seattle, 2012

B.S. Civil Engineering, University of Washington-Seattle, 2009

Publications

2000-present and while at APL-UW

Design of a transducer for fragmenting large kidney stones using burst wave lithotripsy

Randad, A.P., M.A. Ghanem, M.R. Bailey, and A.D. Maxwell, "Design of a transducer for fragmenting large kidney stones using burst wave lithotripsy," Proc. Mtgs. Acoust., 35, 020007, doi:10.1121/2.0000954, 2018.

More Info

5 Nov 2018

Proceedings, 176th Meeting of the Acoustical Society of America, 5-9 November 2018, Victoria, BC, Canada.

Burst wave lithotripsy (BWL) is a potential noninvasive treatment for breaking kidney stones. BWL requirements of high-pressure output, limited aperture for acoustic window, and specific focal length and frequency constrain the focal beam width. However, BWL is most effective only on stones smaller than the beam width. We tested a porous piezoelectric material (PZ36) to increase the output power and designed acoustic lenses that broaden the beam. A weighted iterative angular spectrum approach was used to calculate the source phase distribution needed to generate desired cross sectional focal beam profiles each of 12 mm width. The phase calculations were then 3D printed as holographic lenses placed over a circular aperture of 80-mm diameter, 350 kHz PZ36 to produce the desired beam at 85 mm depth. The difference in simulated beam width and that measured by hydrophone was <1 mm, and the structural–similarity index value was greater than 0.65. The differences in structures were due not to shape and size of the 6-dB contours but to amplitude distribution within the contour. In conclusion, this design approach combined with 3D printing provides a way to tailor focal beam profiles for lithotripsy transducers.

Field characterization and compensation of vibrational nonuniformity for a 256-element focused ultrasound phased array

Ghanem, M.A., A.D. Maxwell, W. Kreider, B.W. Cunitz, V.A. Khokhlova, O.A. Sapozhnikov, and M.R. Bailey, "Field characterization and compensation of vibrational nonuniformity for a 256-element focused ultrasound phased array," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 65, 1618-1630, doi:10.1109/TUFFC.2018.2851188, 2018.

More Info

1 Sep 2018

Multielement focused ultrasound phased arrays have been used in therapeutic applications to treat large tissue volumes by electronic steering of the focus, to target multiple simultaneous foci, and to correct aberration caused by inhomogeneous tissue pathways. There is an increasing interest in using arrays to generate more complex beam shapes and corresponding acoustic radiation force patterns for manipulation of particles such as kidney stones. Toward this end, experimental and computational tools are needed to enable accurate delivery of desired transducer vibrations and corresponding ultrasound fields. The purpose of this paper was to characterize the vibrations of a 256-element array at 1.5 MHz, implement strategies to compensate for variability, and test the ability to generate specified vortex beams that are relevant to particle manipulation. The characterization of the array output was performed in water using both element-by-element measurements at the focus of the array and holography measurements for which all the elements were excited simultaneously. Both methods were used to quantify each element’s output so that the power of each element could be equalized. Vortex beams generated using both compensation strategies were measured and compared to the Rayleigh integral simulations of fields generated by an idealized array based on the manufacturer’s specifications. Although both approaches improved beam axisymmetry, compensation based on holography measurements had half the error relative to the simulation results in comparison to the element-by-element method.

Inventions

Holographic Beam Shaping for Ultrasound Therapy Transducers

Record of Invention Number: 48221

Adam Maxwell, Mike Bailey, Mohamed Ghanem

Disclosure

1 Dec 2017

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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