In the last decade the use of interstitial microwave antennas to deliver localized and controlled power to deep-seated tumours has been explored in institutes around the world. Simultaneously the field of brachytherapy also progressed as clinicans began to develop new implantation approaches for a variety of tumour sites, thereby promoting the insertion of catheters which could serve as conduits for the insterstitial microwave applicators. Although the challenges presented by deep-seated tumours have not been solved, the developments in the field of brachytherapy and the implantation of interstitial applicators for hyperthermia are such that a volume dedicated to this approach is warranted. This third volume in the series “Hyperthermia and Oncology” provides insight in and updated information on various aspects of interstitial hyperthermia. It aims to serve as a guide for clinicians who are either already working in the field or who wish to implement this treatment. It also provides basic aspects to physicists and biologists who are interested in the field of hyperthermic treatment.