Optimizing rf power spatial distribution using frequency control

Abstract

An electro-surgical system actively maintains an optimal heating profile at the electrode-patient contact surface under varying load resistivity, thereby reducing the risk of burns and maximizing patient comfort at a given power level. A set of temperature sensors is integrated within the electrode assembly of the electrosurgical system. The sensors are located both at the center and the edges of the electrode. The sensors are thermally coupled to the electrode-patient contact surface and have a time response that is short compared to the thermal time constraints of the tissue. Some degree of signal processing may take place at the sensor, inside the transducer assembly. As RF power is applied, a control loop monitors the temperature at the center and edges of the electrode. If the edge temperature of the electrode is high compared to its center temperature, then the control loop increases the operating frequency, effectively driving heat towards the center of the electrode. Conversely, if the edge temperature of the electrode is low compared to its center temperature, then the control loop decreases the operating frequency, effectively driving heat towards the edges of the electrode. By actively adjusting the operating frequency in this way, the control loop maintains any chosen heating profile at the electrode-patient contact surface.