Ultrasound applicators for interstitial thermal coagulation

Area of Science:

• Biomedical Engineering
• Medical Physics
• Oncology

Background:

• High-temperature ultrasound interstitial thermal therapy (USITT) requires effective applicator designs for precise tissue heating.
• Evaluating direct-coupled (DC) and catheter-cooled (CC) applicator configurations is crucial for advancing USITT.

Purpose of the Study:

• To evaluate the performance of DC and CC ultrasound applicator configurations for high-temperature USITT.
• To assess the feasibility of achieving therapeutic temperatures and thermal doses in target tissues.

Main Methods:

• Computer simulations were used to model temperature profiles and thermal dose distributions.
• Acoustic beam measurements were conducted to characterize ultrasound energy delivery.
• In vivo temperature measurements were performed to validate simulation results.

Main Results:

• Both DC and CC applicators can achieve target temperatures >50°C and thermal doses >300-600 equivalent minutes at 43°C within 5 minutes at 1-1.5 cm depth.
• Air-cooling in DC applicators significantly enhanced thermal penetration, approaching CC device performance.
• In vivo results confirmed simulation predictions, demonstrating practical power output and steerable heating profiles.

Conclusions:

• DC and CC interstitial ultrasound applicators are practical for controlled thermal coagulation and necrosis of small lesions.
• These devices show potential for treating benign and cancerous lesions in organs like the prostate, liver, and brain.
• Further investigation and development are warranted for clinical implementation of these USITT applicators.