Modified shock waves for extracorporeal shock wave lithotripsy: a simulation based on the Gilmore formulation

Area of Science:

• Biomedical Engineering
• Acoustics
• Urology

Background:

• Extracorporeal shock wave lithotripsy (SWL) is a standard treatment for urolithiasis (kidney stones).
• Cavitation, driven by bubble collapse after shock wave passage, is a key mechanism for stone fragmentation in SWL.
• Enhancing stone fragmentation and minimizing tissue damage remain critical goals for SWL improvement.

Purpose of the Study:

• To investigate the potential advantages of a modified tandem shock wave pulse over conventional tandem SWL.
• To determine if a tandem pulse with a conventional shock wave followed by a slower pressure profile (0.8μs rise time) improves bubble dynamics and cavitation.

Main Methods:

• Utilized the Gilmore equation to simulate the dynamics of a single bubble in water under different shock wave conditions.
• Compared the behavior of bubbles subjected to conventional tandem shock waves versus modified tandem shock waves.
• Analyzed the influence of varying time delays between pulses on bubble collapse dynamics.

Main Results:

• The modified pressure profile significantly enhanced cavitation for a 0.07mm bubble compared to conventional tandem waves across a broad range of delays (10-280μs).
• Similar enhancements in cavitation were observed for a bubble ten times smaller.
• The modified pulse demonstrated improved bubble dynamics, suggesting greater potential for stone fragmentation.

Conclusions:

• The proposed modified tandem pressure profile shows promise for increasing the efficiency of SWL.
• This approach could lead to more effective kidney stone treatment by optimizing cavitation-induced fragmentation.
• Further research into modified tandem SWL may offer a superior alternative to current lithotripsy techniques.