Experimental verification of pulse-probing technique for improving phase coherence grating lobe suppression

Area of Science:

• Medical Imaging
• Acoustics
• Ultrasound Technology

Background:

• High-frequency phased-array ultrasound fabrication is difficult due to small element pitches required to prevent grating lobes.
• Phase coherence imaging (PCI) effectively suppresses grating lobes in large-pitch arrays for synthetic aperture beamforming.
• Previous work theoretically validated pulse probing to improve grating lobe suppression with PCI and transmit beamforming.

Purpose of the Study:

• To experimentally verify the proposed pulse probing technique for grating lobe suppression in high-frequency phased-array ultrasound.
• To demonstrate the effectiveness of pulse probing combined with PCI for improving image quality and simplifying array fabrication.

Main Methods:

• Data acquisition using a 50-MHz, 256-element, 1.26 λ-pitch linear array, utilizing a 64-element aperture.
• Offline processing involving calculation of PCI weighting factors using a defocused pulse.
• Application of calculated weights to conventional transmit-receive beamforming.

Main Results:

• Experimental two-way radiation patterns demonstrated approximately 40 dB suppression of grating lobe levels.
• Suppression of overlapping grating lobes was observed in reconstructed phased array images from wire and tissue phantoms.
• Results were consistent with theoretical predictions, validating the pulse probing technique.

Conclusions:

• The experimental results confirm that pulse probing significantly improves grating lobe suppression when used with PCI in high-frequency ultrasound.
• This technique simplifies the fabrication of large-pitch phased arrays, making them more practical for high-frequency applications.
• The findings pave the way for easier development of advanced ultrasound imaging systems.