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

Microwave absorption cross-sections are strongly dependent on size and shape when the dimensions of the tissue are comparable to the wavelength of the microwaves, but this effect is minimized when the tissue is immersed in a microwave tissue equivalent liquid bolus system. Measurements have been made of the permittivities of physiologically compatible solutions of dextran in Krebs-Ringer solution. Temperature measurements showed that the bolus was maintained near the target temperature, and thermal uniformity was much improved using the bolus system. Potential applications in radiobiology and radiotherapy are briefly discussed. (U.K.)