Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method

Area of Science:

• Fluid Dynamics
• Acoustics
• Biomedical Engineering

Background:

• Lithotripsy utilizes shock waves to break kidney stones.
• Acoustic streaming, fluid motion induced by sound waves, is a byproduct of lithotripsy.
• Understanding acoustic streaming is crucial for optimizing lithotripsy procedures and minimizing tissue damage.

Purpose of the Study:

• To visualize and quantify acoustic streaming in water generated by lithotripsy pulses.
• To investigate the relationship between acoustic intensity and streaming velocity.
• To correlate streaming velocity with peak negative pressures.

Main Methods:

• Employed particle image velocimetry (PIV) to visualize acoustic streaming.
• Used an electromagnetic shock wave generator to produce lithotripsy pulses in water.
• Suspended light-scattering particles in water to capture streaming patterns via video imaging.

Main Results:

• Observed distinct streaming features, including peaks and vortices, at the beam focus.
• Measured peak streaming velocities ranging from 10-40 mm/s, dependent on charging voltage.
• Demonstrated a proportional relationship between streaming velocity and acoustic intensity.
• Found a strong linear correlation between streaming velocity and peak negative pressures (r=0.98683).

Conclusions:

• Particle image velocimetry effectively visualizes acoustic streaming from lithotripsy.
• Streaming velocity is directly related to acoustic intensity and peak negative pressure.
• Findings support theoretical predictions regarding acoustic streaming in lithotripsy.