Journal of Okayama Medical Association
Published by Okayama Medical Association

Full-text articles are available 3 years after publication.


Matsumi, Nobuhiko
101_1049.pdf 3.54 MB
The thermal damage threshold of brain tissue was estimated from the immediate and delayed histological changes caused by 2450 MHz microwave antenna and an antenna cooling system of a device used for interstitial hyperthermia treatment. An antenna within a cooling system was inserted through the small cranietomy under general anesthesia. The temperature at a reference point, 4 mm radially away from the surface of the cooling system, was maintained at 42 °C, 43 °C, 44 °C, 45 °C or 46 °C for 60 minutes. In a non-survival experiment, 18 animals were used and sacrificed immediately after the treatment. In a survival experiment, 9 animals were used and sacrificed seven days after the treatment. The histological changes were evaluated by microscopic examination with hematoxylin and eosin, Klüver-Barrera, or Bodian stainings. In the non-survival experiment, areas heated below 44 °C showed no obvious irreversible change. In the survival experiment, areas heated at 44 °C or above showed coagulative necrosis. Those histological findings indicate that the thermal damage occurs in normal brain tissue after heating at 44 °C or above for 60 minutes, and suggest that the safety limit for brain hyperthermia is 43 °C for 60 minutes.
interstitial microwave irradiation
histological change
malignant brain tumors
antenna cooling system