Temperature Distribution of Radiofrequency Hyperthermia in a Capacitance System in Breast Equivalent Tumor Ablation: A Simulation Study

Abstract

Introduction: For decades, hyperthermia had been used for tumor ablation by increasing the temperature of cancerous tissues. For clinical treatment, a capacitance system was developed over the world, widely. In this study, a capacitance system of the radiofrequency hyperthermia is simulated to achieving the temperature distribution map of the entire breast equivalent phantom. Therefore, the efficiency of this method in treating the breast cancer was investigated. Materials and Methods: In this paper, a radiofrequency system with a frequency of 13.56MHz was simulated by Comsol multiphysics software. The geometry of the breast cancerous tissue by considering three different tissues including the fat, the gland and the tumor was modeled. The two electrodes of the system were modeled as two disks with a radius of 15cm with the water bolus for cooling the healthy tissues. The calculations of the radiofrequency wave and the bioheat equation were accomplished by numerical simulation and finite element method (FEM). Results: The temperature plots were obtained in 5 minutes. The results were compared with experimental results to checking the accuracy of the radiofrequency device and the precision of the thermometry device. The Temperature distribution map was achieved in 3D to investigate the increasing temperature amount of the cancerous and the healthy tissues, entirely. Conclusion: The results was shown that the temperature of the whole tumor region increased equal, approximately (3-4 ˚C). Moreover, the temperature of the whole healthy tissues (the gland and the fat) did not increase, highly (1.9- 2.1 ˚C). Hence, in the capacitive hyperthermia system, the tumor reaches extreme heat while the healthy tissues are protected from damages, completely. On the other hand, the difference between the simulation and the experimental results were about 9-15%, approximately. Therefore, the accurate operation of the radiofrequency device and the precise of the thermometry device were confirmed, either.