Design and test of microwave interstitial applicators with improved longitudinal heating pattern.

A microwave applicator for interstitial hyperthermia was designed for use in conjunction with interstitial radiation therapy. Measurements were performed in phantom material and in the hind legs of anaesthetized pigs. In both studies two applicators were inserted in parallel at a distance of 2 cm and to a depth of 6 cm. The temperature distribution produced by two conventional applicators were compared with the temperature distribution produced by two applicators of the new design. Improvement of the heating pattern was found in both phantom and animal studies; the heating pattern produced by the new applicators was shifted towards the tip. This may be of clinical importance as heating can be achieved without applicator penetration through tumour tissue into normal tissue.