A new design method for extracorporeal high-intensity focused ultrasound annular array

Area of Science:

• Medical Physics
• Biomedical Engineering
• Acoustic Technology

Background:

• High-intensity focused ultrasound (HIFU) tumor ablation requires careful consideration of normal tissue damage.
• Preventing skin burns and damage to tissues behind the tumor is crucial for safe HIFU treatment.

Purpose of the Study:

• To design an annular array for HIFU tumor ablation that prevents skin burns and minimizes damage to normal tissues.
• To determine optimal array configurations and operating frequencies for enhanced focusing range and therapeutic efficacy.

Main Methods:

• Numerical simulation of acoustic intensity fields using the Rayleigh-Summerfield pressure integral.
• Design and analysis of a spherical bowl annular array (12 cm diameter, 12 cm radius of curvature).
• Development of an absorbed intensity ratio to define allowable grating lobes and focusing range.

Main Results:

• For uterine fibroids, increasing array elements (9 to 22) extended focusing range.
• A 14-ring array at 0.8-1.0 MHz offered a >5.5 cm focusing range, compared to 4 cm at 1.2 MHz.
• For breast cancers (medullary and scirrhous), the 0.9 MHz, 14-ring array achieved focusing ranges of 8-12 cm and 8-14 cm, respectively.

Conclusions:

• The designed annular array effectively enhances the focusing range for HIFU tumor ablation.
• Optimized array design and frequency selection are critical for safe and effective treatment of uterine fibroids and breast cancers.
• This approach minimizes collateral damage to surrounding healthy tissues during HIFU therapy.