A physiologically compatible tissue-equivalent liquid bolus for microwave heating of tissues

Abstract

Hyperthermia used alone, or in conjunction with ionizing radiation or cytotoxic agents, can be a useful addition to existing techniques in treating cancer. This technique uses a physiologically compatible and microwave tissue-equivalent bolus system to provide efficient microwave coupling to irregularly shaped tissues without adversely affecting those tissues. The technique minimizes shape and size dependence of microwave energy absorption. In addition, by maintaining the temperature of the bolus near target temperature, the thermal uniformity may be much improved over that obtained by simply exposing the irregularly shaped tissue to microwaves in air. Such an approach should be useful in developing uniform heating of small laboratory animals. The liquid bolus could be used in direct contact with the skin in treatments involving microwave heating of superficial lesions in human patients, and would allow the transformation of the complex shapes of treated areas into ones of simple plane geometry. The effective depth of penetration of the microwaves could be increased by using a refrigerated bolus to maintain a patient''s skin and superficial tissue at a controlled and reduced temperature.