Comparison of the clinical effectiveness of the 433 MHz lucite cone applicator with that of a conventional waveguide applicator in applications of superficial hyperthermia

Purpose: This report presents the final stage of our program to improve the quality of our superficial hyperthermia treatments. We have already demonstrated that the Lucite cone applicator (LCA), our technically improved water-filled, wave-guide applicator (WGA), is superior to the conventional WGA, The main objective of the present study was to investigate whether the technical improvements of a WGA were reflected in an improved clinical performance, e.g., a better temperature distribution. Methods and Materials: Power and temperature analyses were performed retrospectively on 128 treatments of superficially located tumors (less than 4 cm depth). Twenty-three patients were treated alternately with a WGA setup and a LCA setup. Results: The average power level per antenna in an array was 48 W and 62 W for the WGA and LCA respectively. The average invasively measured temperatures increased by 0.27 degrees C when the LCAs mere used. The temperature difference between the center and the periphery of an antenna, averaged over the complete array of antennae, was 0.43 degrees C using WGAs and -0.05 degrees C using LCAs indicating a more uniform heating, The T-90 of the invasively measured temperatures remained unchanged (WGA: 39.4 degrees C versus LCA: 39.5 degrees C). Conclusion: The LCA is now our standard applicator for superficial hyperthermia treatments as it is technically and clinically proven to be superior to the WGA. (C) 1999 Elsevier Science Inc.