Time reversal focusing applied to lithotripsy

Area of Science:

• Acoustics
• Medical Imaging
• Biomedical Engineering

Background:

• Time reversal of ultrasonic fields offers efficient focusing through inhomogeneous media.
• Time reversal mirrors (TRM) utilize transducer arrays for sampling, time-reversing, and re-emitting acoustic fields.
• Iterative TRM processing can converge on dominant scatterers in multitarget environments.

Purpose of the Study:

• To investigate the application of time reversal processing for real-time tracking of moving gall bladder or kidney stones.
• To assess the feasibility of using a piezoelectric shock wave generator with electronically steered focal zones for lithotripsy.
• To demonstrate sharp focusing on specific points of a moving stone using TRM.

Main Methods:

• Employing time reversal mirrors (TRM) with large transducer arrays.
• Implementing iterative time reversal processing to target dominant scatterers.
• Utilizing a piezoelectric shock wave generator with electronically controlled focal zones.
• Determining the time-of-flight profile of the targeted stone.
• Applying a least-mean-square method for spatial coordinate calculation.

Main Results:

• TRM successfully achieved sharp focusing on a single bright point of a moving stone.
• The time-of-flight profile was accurately determined.
• Spatial coordinates of the stone were calculated using the least-mean-square method.
• Demonstrated feasibility for real-time tracking during simulated lithotripsy.

Conclusions:

• Time reversal processing is a viable method for real-time tracking of moving gall bladder or kidney stones.
• TRM enables precise focusing for potential applications in medical treatments like lithotripsy.
• The developed method allows for accurate spatial localization of embedded moving targets.