An evaluation of microwave diathermy systems using temperature increase distributions produced by ultrasound imaging techniques

Thermotherapy is used to inhibit the progress of osteoarthritis (OA) and to ease pain and stiffness. Effective thermotherapy occurs when heat can deeply penetrate the joint tissue, such as the cartilage and the joint cavity. The microwave diathermy system does not contact the patient's skin; however, our previous findings show that its heat penetration depth is less than 20mm, which is not enough to heat the deep tissue for effective treatment of OA. In this study, we developed a method using ultrasound (US) imaging techniques to calculate temperature increase distributions inside the human body. With this method, we evaluated the heating performance of current microwave diathermy systems. Finally, we compared our experimental data with computer-simulated temperature increase distributions using the finite element method (FEM).