A system for monitoring and/or controlling tissue modification during an electrosurgical procedure is provided. The system includes an electrosurgical apparatus adapted to connect to an electrosurgical generator. The electrosurgical apparatus configured to transmit energy to tissue. The system also includes a control system having one or more electromagnetic wave sources configured to generate the interrogator wave of one or more frequencies adjacent tissue. One or more sensors are configured to transmit and sense a reflected portion of the interrogator wave of at least one frequency to determine dielectric boundary data. A processor operatively coupled to the control system and to the electrosurgical generator configured to control the delivery of electrosurgical energy from the electrosurgical generator to tissue based on dielectric boundary data provided by the one or more sensors.
