Planning of hyperthermic treatment for malignant glioma using computer simulation

Interstitial hyperthermia was applied using a radiofrequency generator in t he treatment of four malignant glioma patients who had especially deep seat ed brain tumours or were at high risk. Prior to heating tumours, treatment planning based on all accurate prediction of temperature distribution is es sential. The present paper introduces a novel treatment planning method and discusses its clinical efficacy. The two-dimensional finite element method was used for simulation of temperature distribution, which was calculated using the bioheat transfer equation. This technique was applied to plan tre atment. Temperature was measured at two points during heating and these val ues were compared with those estimated by the simulation. In addition, the area of the contrast enhanced (CE) rim on the pre-heating computed tomograp hy (CT) image was compared with the low density area of the CE rim on the p ost-heating CT image, which was obtained within 2 months after heating. The optimal position and number of radiofrequency (RF) electrodes to include t he outside of the CE rim in the simulated area above 42 degreesC contour co uld be easily determined using this planning system in all cases. The tempe rature estimated by the simulation was in good agreement with the actual va lues obtained (within 0.4 degreesC). The post-heating CT image revealed tha t the hyperthermic procedure described herein achieved more than an 80% low density area within the CE rim in all cases (mean 86.0%). These results de monstrate that this novel treatment planning method may prove to be a clini cally valuable tool in the treatment of malignant glioma with RF electrodes .