Preclinical evaluation of submillimeter diameter microwave interstitial hyperthermia applicators

Area of Science:

• Biomedical Engineering
• Medical Physics
• Oncology

Background:

• Interstitial hyperthermia is a cancer treatment modality.
• Current hyperthermia applicators have limitations in size and invasiveness.
• Minimally invasive techniques are crucial for treating deep-seated tumors.

Purpose of the Study:

• To develop and evaluate ultra-miniature interstitial hyperthermia applicators.
• To assess the efficacy and safety of novel small-diameter applicators.
• To determine the potential of these applicators for clinical use in cancer treatment.

Main Methods:

• Fabrication of ultra-miniature applicators (0.20-0.58 mm diameter) using microscopic techniques and coaxial cable.
• Measurement of heating patterns (Specific Absorption Rate - SAR) in tissue-simulating phantoms using a miniature electric field probe.
• Evaluation of applicator performance in perfused animal tissue models (pig thigh and liver).

Main Results:

• Ultra-miniature applicators produced less local tissue trauma compared to larger commercial devices in animal studies.
• Applicators demonstrated adequate durability and power handling for patient use.
• Heating patterns were consistent across different applicator sizes due to scaled design and monopole operation at 915 MHz.

Conclusions:

• Ultra-miniature hyperthermia applicators offer a promising alternative to larger devices, with reduced tissue trauma.
• These applicators are suitable for percutaneous, intraoperative, intraluminal, and intravascular tumor treatments.
• Further clinical trials are warranted to validate the efficacy of these novel applicators.