Design and evaluation of a feedback based phased array system for ultrasound surgery

Area of Science:

• Ultrasound technology
• Electrical engineering
• Biomedical engineering

Background:

• Phased array ultrasound applicators require sophisticated driving systems for precise control.
• Variations in power and phase between array elements can degrade ultrasound beamforming and focal intensity.
• Existing systems may lack the necessary resolution or feedback mechanisms for optimal performance.

Purpose of the Study:

• To design and evaluate a novel driving system for phased array ultrasound applicators.
• To achieve independent, high-resolution power and phase control for each array element.
• To enhance the stability of RF electrical power and improve focal intensities in ultrasound arrays.

Main Methods:

• Development of a driving system operating in the 1.2 to 1.8 MHz bandwidth.
• Implementation of independent channel power control up to 60 W with 8-bit resolution.
• Utilization of switching regulators in a feedback loop to stabilize DC supply for Class D/E power converters.
• Integration of 360-degree phase shifting with a minimum of 8-bit resolution per channel.
• Inclusion of RF driving channel phase feedback for accurate signal phasing at the transducer.

Main Results:

• RF electrical power variation reduced from 20% to 1% across a 16-element array.
• Achieved DC-to-RF efficiencies close to 70% across all power levels, minimizing heat dissipation.
• Experimentally demonstrated a 20% to 25% increase in focal intensities for tested phased arrays.
• Eliminated the need for array calibration using a hydrophone due to effective phase feedback.

Conclusions:

• The designed driving system provides stable and precise control over power and phase for phased array ultrasound.
• The feedback mechanisms significantly enhance RF power consistency and focal intensity, improving overall system performance.
• This technology offers a robust solution for driving ultrasound arrays, particularly those with varying element sizes, without extensive calibration.