A Prototype Therapy System for Transcutaneous Application of Boiling Histotripsy

Area of Science:

• Medical Physics
• Biomedical Engineering
• Acoustic Surgery

Background:

• Boiling histotripsy (BH) uses focused ultrasound pulses to create liquefied lesions noninvasively.
• Achieving high in situ pressures for BH through intervening tissue requires specialized apparatus.

Purpose of the Study:

• To design and characterize a system for transcutaneous boiling histotripsy therapy.
• To generate the necessary high-amplitude shock waves for BH through clinically relevant tissue depths.

Main Methods:

• A high-voltage pulser drove a 1-MHz focused ultrasound transducer for millisecond pulses.
• Numerical modeling (3-D Westervelt equation) and acoustic holography characterized system output.
• In situ pressure estimation used a derating method for nonlinear therapeutic fields.

Main Results:

• The system generated shock waves sufficient for boiling within the pulse duration.
• Simulations agreed with measured focal waveforms.
• BH lesions were created ex vivo in liver up to 7 cm deep and through porcine body wall (3-5 cm thick).

Conclusions:

• The developed system can produce the required output for transcutaneous boiling histotripsy.
• This technology shows promise for noninvasive tissue ablation via BH therapy.