Gated Transmit and Fresnel-Based Receive Beamforming With a Phased Array for Low-Cost Ultrasound Imaging

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Signal Processing

Background:

• Low-cost ultrasound systems are crucial for expanding applications beyond traditional radiology and cardiology.
• Miniaturization and cost reduction are key drivers for broader adoption in areas like emergency and critical care.
• Existing ultrasound systems face limitations in cost and size for widespread point-of-care use.

Purpose of the Study:

• To investigate novel Fresnel-based beamforming methods for miniaturizing and reducing the cost of ultrasound systems.
• To extend Fresnel-based beamforming to phased arrays with beam steering capabilities.
• To evaluate the performance of Fresnel-based beamforming against standard delay-and-sum (DAS) beamforming.

Main Methods:

• Developed a gated transmit beamformer using multiplexers for multicycle bursts.
• Implemented Fresnel beamforming on subapertures of a phased array in receive mode.
• Combined Fresnel beamforming with dual apodization with cross correlation (DAX) to suppress sidelobes and clutter.
• Utilized Field II simulations for spatial resolution and contrast-to-noise ratio evaluation.
• Performed experiments using synthetic aperture data and a hardware proof-of-concept (PoC) Fresnel beamformer.

Main Results:

• Fresnel-based beamforming demonstrated comparable imaging performance to DAS beamforming in previous studies.
• The extended Fresnel method for phased arrays with beam steering was successfully implemented.
• Simulations and phantom studies showed the potential of Fresnel beamforming for improved ultrasound imaging.
• The hardware PoC validated the feasibility of the developed Fresnel beamformer.

Conclusions:

• Novel Fresnel-based beamforming techniques, including gated transmit and phased array receive methods, offer a promising path to lower-cost, miniaturized ultrasound systems.
• The integration with DAX effectively mitigates timing errors inherent in Fresnel beamforming, improving image contrast.
• This approach has the potential to significantly expand the accessibility and application range of ultrasound technology in diverse clinical settings.