Radio-frequency current application in bipolar technique for interstitial thermotherapy (rf-ITT)

摘要

Abstract: For the interstitial treatment of pathologic tissue,e.g. tumors, the benign prostate hyperplasia or theconcha hyperplasia in otorhinolaryngology, the methodof interstitial laser photocoagulation and themonopolar RF- needle coagulation can be used as well asother methods, e.g. the microwave exposure, alcoholinjection, ultrasound or hot water irrigation. Thisarticle will present latest results of interstitialthermotherapy with radio-frequency alternating currentin bipolar technique. Therefore basic investigations ofthe thermal field distribution in in vitro samples wereperformed. THe efficiency of the developed applicatorswere examined using egg white and in in vitroexperiments with porcine liver tissue. Bipolar needleswith different diameters were built and tested.Carbonization and dehydration can be avoided byirrigation of the tissue during treatment through anintegrated central flushing port. A bipolar needle hasbeen developed for the treatment of concha hyperplasiawhich can be used as the monopolar pendant with similarresults in partial tissue coagulation but withoutcurrent flow in the sensitive head region. Firstpathologic investigations pointed out that with the useof the bipolar technique the surface of the concha withthe ciliary epithelium is less affected due tot helimited spatial current distribution. Furthermore thedesign of a multi-electrode needle is presented whichcould probably offer an additional increase of safetyand a simplification of performing a concha coagulationprocedure. The new design of a bipolar needle electrodeenables the surgeon the use of a partial application ofradio frequency current for ITT. Less power is neededdue to the limited current distribution at theimmediate operation site, which means that a neutralelectrode is not needed. Thus a highly safe procedurecan be performed by the surgeon. !15