Evolution of acoustically vaporized microdroplets in gas embolotherapy

Area of Science:

• Fluid dynamics
• Acoustic cavitation
• Biomedical engineering

Background:

• Gas embolotherapy is a developing cancer treatment.
• Tumor infarction using gas bubbles is a key mechanism.
• Understanding bubble dynamics is crucial for effective treatment.

Purpose of the Study:

• Investigate acoustic vaporization dynamics of dodecafluoropentane (DDFP) microdroplets in microtubes.
• Analyze bubble evolution and stress distribution during vaporization.
• Inform the development of gas embolotherapy techniques.

Main Methods:

• Combined theoretical and computational approach.
• Ultra-high speed imaging for transient bubble growth.
• Comparison with experimental data.

Main Results:

• Bubble evolution exhibits three regimes: rapid spherical, compressed oval, and asymptotic spherical growth.
• Tube walls influence bubble evolution, even for small droplets.
• Final bubble radius scales linearly with initial droplet size (approx. 5x).
• A pressure pulse (amplitude ~2x ambient) is observed, with width dependent on droplet size.

Conclusions:

• The study elucidates bubble evolution dynamics in confined microfluidic environments.
• Results provide insights into stress distribution relevant to embolotherapy.
• Findings support the potential of acoustic vaporization for targeted tumor infarction.