[Increasing the thermal enhancement ratio by simultaneous application of radiation and hyperthermia--technical possibilities in interstitial application].

Whereas the cytotoxic effect of hyperthermia is independent and without any time relationship with the radiation treatment, the heat induced radiosensitization only appears with simultaneous application of radiation and heat. Although the highest thermal enhancement ratio (TER) can be achieved with simultaneous application this protocol is not used in clinical practise because of technical problems. From a practical point of view the major effect of a non simultaneous application will have to rely on hyperthermic cytotoxicity. A two-zone needle which offers the possibility to conduct radiation and heat simultaneously in order to confine this to a three-dimensional radiation and heat is described.