One mechanical method of ablation involves the use of radiofrequency thermal technology, also called radiofrequency ablation (RFA). The RFA procedure involves inserting an RF electrode into the center of a hepatic tumor mass under ultrasonic or CT guidance. Radiofrequency energy is then applied through the electrode, causing a thermal injury to the surrounding tumor tissue. Currently there are two basic designs for monitoring inter-procedural progress during RFA; temperature monitoring of set points within the target tissue with thermocouples, or assessing the system-wide impedance of tissue adjacent to the deployed electrode tines. Radiofrequency ablation systems are comprised of three components: a radiofrequency generator, an active electrode, and dispersive electrodes.