Interstitial helical coil microwave antenna for experimental brain hyperthermia

Area of Science:

• Biomedical Engineering
• Neurosurgery
• Medical Physics

Background:

• Interstitial hyperthermia is a promising therapeutic modality for brain tumors.
• Effective delivery requires precise temperature control and localized heating.
• Existing microwave antennas, like dipole antennas, may cause superficial heating.

Purpose of the Study:

• To evaluate a helical coil microwave antenna for inducing interstitial hyperthermia in normal canine brain.
• To compare the heating patterns of the helical coil antenna with a standard dipole antenna.
• To assess the safety and reproducibility of helical coil antenna-induced hyperthermia.

Main Methods:

• A 2450-MHz helical coil antenna (HCS-10(1)/11) was implanted stereotactically into normal dog brains.
• Temperature distributions were measured using multiple probes.
• Heating patterns were compared to those generated by a 2450-MHz dipole antenna; thermal lesions were visualized post-treatment using CT.

Main Results:

• The helical coil antenna produced well-localized, symmetrical heating patterns extending to the antenna tip.
• Minimal variation in heating occurred with insertion depth, and extracerebral tissues were not overheated.
• Dipole antennas caused significant superficial brain and extracerebral tissue heating, with lower targeted brain temperatures.

Conclusions:

• The helical coil antenna enables localized interstitial hyperthermia in the brain without damaging surrounding tissues.
• This antenna is suitable for studying brain responses to heat and may be effective for treating malignant brain tumors.