On the optimization of local hyperthermy in tumors based on a new radiofrequency procedure. Local hyperthermy of large body areas using the CMT selectotherm method.

A new radiofrequency procedure, i.c., the CMT Selectotherm technique, permits to convey large heat quantities per volume unit also to deep-seated tumor tissues without causing thermal lesions in healthy tissues near or at the body surface. The improved spatial homogeneity of energy supply attainable by this method is demonstrated by measurements at a gelatine phantom and, in particular, by in vivo measurements on pigs. The appliability of local hyperthermy to tumors localized in different parts of the body is substantially improved (a) by the principle of superimposing local hyperthermy on an elevated temperature level of metabolically induced whole-body hyperthermy (CMT-spontaneous hyperthermy at 40 degrees C) and (b) by the principle of selective increasing the thermal sensitivity of tumor tissues by decreasing the pH in these areas (the CMT main step). It is shown that the temperature dose T. deltat necessary for the selective occlusion of the vasculature in tumor tissues can be obtained by the CMT Selectotherm process also in deep-seated tumors. This process is part of the 1977 CMT concept. The fundamentals of optimizing local hyperthermy with consideration of heat dissipation from the tissue by heat conduction and convection via the blood stream are demonstrated. Temperature profiles are calculated for some practice-relevant, typical examples (inner and outer parts of sphero-symmetrically shaped tumors). Finally, in vivo measurements and calculations on the time course of temperature under certain conditions and for different tissue layers are discussed.