Daxsonics CTO, Dr. Jeremy Brown, has been awarded $2.7 million from the federal government for a cutting edge surgical probe.
Christopher A. Samson, Katherine Latham, and Jeremy A. Brown
School of Biomedical Engineering. Dalhousie University Halifax, Canada
Abstract—A digital variable sampling high-frequency beamformer implementing real-time grating lobe suppression is described. The system is tested using a semi-kerfed 64 element 45 MHz phased array with 1λ element pitch. The grating lobe suppression is facilitated with the sign coherence factor (SCF) and split-aperture transmit beamforming techniques. A new split-aperture transmit technique called “sub-aperture probing” (SAP) is described, experimentally validated, and compared to previously developed split-aperture techniques with respect to grating lobe suppression. Grating lobe levels were suppressed to be 49 and 60 dB below the main lobe when using 2 split-apertures with a SCF weighting factor of 1 and 2. These levels were further suppressed to 51 and 66 dB below the main lobe when splitting the aperture into 4 evenly sized apertures. When using SAP with 16 elements for the sub-aperture, grating lobes were suppressed to 49 and 64 dB below the main lobe. SAP with 8 elements yielded improved results compared to SAP with 16 elements; suppressing grating lobe levels to 49 and 65 dB below the main lobe for the associated SCF weighting coefficients. Finally the grating lobe suppression performance was tested on a wire target embedded in a tissue phantom and the signal to tissue speckle levels were characterized.
Jeffrey Woodacre*, Thomas Landry, Jeremy Brown
Department of Biomedical Engineering Dalhousie University
Halifax, Nova Scotia, Canada Corresponding Author*: firstname.lastname@example.org
Abstract—. In this work, we have developed a small, handheld histotripsy transducer where the ablation focus is imaged in real- time using a co-registered 45 MHz 64-element phased array endoscope. The construction of a 2 cm diameter, 40% volume fraction, strongly curved, PZT5A composite transducer capable of generating cavitation within tissue is outlined. The co- registered imaging and ablation tool was able to ablate a 1 mm x 0.5 mm x 0.5 mm volume below the surface of a chinchilla brain using a single 5 second, 1 kHz PRF, 10 cycle burst, without damage to the surface leading to the ablation site. Total electrical power draw during treatment was less than 4 W.
Hugo Vihvelin, a Masters of Biomedical Engineer student with Dalhousie University, has been nationally recognized for outstanding innovation during his MITACS funded internship with with Daxsonics Ultrasound.
The project involves the development of a power amplifier for driving therapeutic ultrasound transducers such as those used in non-invasive surgeries and cancer treatments. The design makes use of a unconventional amplifier topology, class E/F, and advanced GaN FET technology in order to maximize amplifier efficiency. High efficiency amplifiers are important to reduce the number of fans and heat sinks needed in the ultrasound systems, allowing them to be cooler, lighter, lower cost, and more portable.
MITACS Award Information:
University: Dalhousie University
Intern: Hugo Vihvelin
Faculty Supervisor: Geoff Maksym
Partner: Daxsonics Ultrasound Inc.
Sector: Advanced manufacturing
Discipline: Engineering - biomedical