Resonant cavity heating of cryopreserved tissue [for application to hyperthermia treatment]

Previously the authors described the dielectric measuring system which they used to investigate samples of kidney tissue perfused with cryoprotectant solutions. They found the open-ended coaxial probe to be most suitable. Results were given for different perfusates, from 50 MHz to 2.6 GHz, and from -30 to +20°C. It was concluded that some perfusates already in use in medical cryobiology laboratories are much more favourable than others from the EM heating point of view, and that there is a broad optimum from 300 MHz to 1 GHz in frequency to be used. In the present work the factors considered in reaching this conclusion, the temperature coefficient of the effective electrical conductivity, especially near the phase change, and the power penetration depth in a uniform external field, are examined