Interstitial hyperthermia.

The effectiveness of hyperthermia as a treatment modality for cancer continues to gain popularity in the medical community. One of the disappointing findings has been the inability to deliver uniform thermal doses to tumor volumes. This inability to heat certain tumors is due to a variety of physical and physiologic phenomena. To increase the ability of heating tumors, local interstitial techniques have been developed that are proving to be safe and effective. These techniques employ implanted microwave or radiofrequency antennae for the delivery of local thermal doses. Recently, investigations into the placement of interstitially located ferromagnetic seeds for local hyperthermia have also been conducted. The seeds can be heated by delivery of a high-wattage RF magnetic field to the implanted volume by an external source after implantation. The tissue surrounding the ferromagnetic implant is heated by conduction of heat away from the implanted seeds. While these techniques have been effective, further development of the instrumentation for interstitial therapies is continuing. These developments will include the application of specific control circuitry for delivery of accurate thermal doses.