In the modern surgical operation, some energy devices are employed for hemostasis (tissue coagulation) and dissection. They are an electrical scalpel and an ultrasonically activated scalpel. These devices are essential surgical tools. However, there are some problems should be improved. Especially, in the WaFLES, these energy devices sometimes induce the problems. Therefore, in this study, tissue coagulation devices by microwave energy, which can improve some problems of conventional devices, is developed. Moreover, performances of the developed devices will be evaluated by numerical calculation of electromagnetic field and animal experiments. In this study, microwave device, whose outer diameter is around 20 to 30 mm, have been developed (Fig. 1). This device can be inserted into a port for the laparoscopic surgery. Moreover, the device must be radiated the microwave energy only around the tip where is pressed the tissue. The performances of the device is analyzed by finite-difference time-domain (FDTD) calculations. This technique is widely used for performance evaluation of microwave antenna. In this study, heating pattern around the devices are calculated by this method. In addition, biological tissues are coagulated by the prototype devices in the animal experiments (Fig. 2). From these results, effectiveness of the microwave devices could be confirmed. As a further study, prototype devices, which can be used for actual surgical treatment, will be developed by considering usability of operators.
Left: Developed microwave tissue coagulation device (prototype). Operating frequency is 2.45 GHz.
Right: Tissue coagulation by prototype device under WaFLES (bladder surface). Input power of the device is approx. 50W.