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Mohamed Ghanem

Postdoctoral Scholar

Email

mghanem@apl.uw.edu

Phone

206-616-7317

Education

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

M.S. Aerospace & Aeronautical Engineering, University of Washington - Seattle, 2012

Ph.D. Aerospace & Aeronautical Engineering, University of Washington - Seattle, 2018

Publications

2000-present and while at APL-UW

Noninvasive acoustic manipulation of objects in a living body

Ghanem, M.A., A.D. Maxwell, Y.-N. Wang, B.W. Cunitz, V.A. Khokhlova, O.A. Sopozhnikov, and M.R. Bailey, "Noninvasive acoustic manipulation of objects in a living body," Proc. Nat. Acad. Sci. USA, 117, 16,848-16,855, doi:10.1073/pnas.2001779117, 2020.

More Info

21 Jul 2020

In certain medical applications, transmitting an ultrasound beam through the skin to manipulate a solid object within the human body would be beneficial. Such applications include, for example, controlling an ingestible camera or expelling a kidney stone. In this paper, ultrasound beams of specific shapes were designed by numerical modeling and produced using a phased array. These beams were shown to levitate and electronically steer solid objects (3-mm-diameter glass spheres), along preprogrammed paths, in a water bath, and in the urinary bladders of live pigs. Deviation from the intended path was on average <10%. No injury was found on the bladder wall or intervening tissue.

Design, fabrication, and characterization of broad beam transducers for fragmenting large renal calculi with burst wave lithotripsy

Randad, A., M.A. Ghanem, M.R. Bailey, A.D. Maxwell, "Design, fabrication, and characterization of broad beam transducers for fragmenting large renal calculi with burst wave lithotripsy, " J. Acoust. Soc. Am., 148, 44-50, doi:10.1121/10.0001512, 2020.

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1 Jul 2020

Burst wave lithotripsy (BWL) is a technology for comminuting urinary stones. A BWL transducer's requirements of high-pressure output, limited acoustic window, specific focal depth, and frequency to produce fragments of passable size constrain focal beamwidth. However, BWL is most effective with a beam wider than the stone. To produce a broad-beam, an iterative angular spectrum approach was used to calculate a phase screen that was realized with a rapid prototyped lens. The technique did not accurately replicate a target beam profile when an axisymmetric profile was chosen. Adding asymmetric weighting functions to the target profile achieved appropriate beamwidth. Lenses were designed to create a spherically focused narrow-beam (6 mm) and a broad-beam (11 mm) with a 350-kHz transducer and 84-mm focal depth. Both lenses were used to fragment artificial stones (11 mm long) in a water bath, and fragmentation rates were compared. The linearly simulated and measured broad beamwidths that were 12 mm and 11 mm, respectively, with a 2-mm-wide null at center. The broad-beam and the narrow-beam lenses fragmented 44 ± 9% and 16 ± 4% (p = 0.007, N = 3) of a stone by weight, respectively, in the same duration at the same peak negative pressure. The method broadened the focus and improved the BWL rate of fragmentation of large stones.

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.

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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.

More Publications

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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