Ultrasound Technology for Interstitial Hyperthermia

Abstract

Interstitial methods are most often used for treating bulky or unresectable deep-seated tumors or sites which are difficult to reach by external methods in the pelvis, intra-abdominal, and head and neck regions. Despite the invasive nature of the techniques, interstitial heating remains a treatment of choice, for many tumors since the heating sources are inserted directly into the tumor, thereby localizing the heating to the target volume and sparing more of the surrounding normal tissue. Currently radiofrequency local current field (RF-LCF) electrodes, coaxial cable mounted microwave antennas, inductively heated ferromagnetic seeds, resistance wire, and hot water tubes are used for interstitial hyperthermia (Stauffer 1990; Seegenschmiedt et al. 1991; Coughlin and Strohbehn 1989). Although efficacious in many clinical situations, none of these methods (except hot sources) allows the power deposition to be easily varied along the length of the implant during the course of a treatment to account for heterogeneities in tumor structure and dynamic changes in blood perfusion.