Electrosurgical medical system and method
A medical device system and method provide an RF electrosurgical generator coupled to an electrosurgical electrode via a patient box disposed in close proximity to the patient. An RF signal is delivered from the generator to the patient box where signal power is increased and the RF signal delivered to the electrosurgical electrode. The patient box is coupled to the electrosurgical electrode by a short cable capable of carrying an HV, high frequency 5 MHz signal without leakage. An electrical characteristic associated with the electrosurgical electrode is monitored and a desired RF power output and duty cycle maintained by adjusting DC input voltage applied to an RF amplifier, responsive to the monitoring. The system determines when the electrosurgical cutting electrode has started cutting and switches from a start mode to a run mode having a different RF duty cycle and a reduced RF power output controlled by a servo system.
1. A system for controlling an electrosurgical electrode of a medical device comprising:
an electrosurgical electrode;
an RF generator coupled to said electrosurgical electrode, said RF generator including an RF amplifier, said RF generator being configured to generate an RF signal at a first RF power level for tissue cutting and generate said RF signal at a second RF power level greater than the first RF power level to initiate tissue cutting, said first RF power level being associated with a cutting mode of said RF generator and said second RF power level being associated with a start mode of said RF generator;
a sensor for monitoring an electrical characteristic associated with said electrosurgical electrode;
a controller coupled to said RF amplifier, said controller configured to maintain a desired RF power output and a desired RF duty cycle at said first RF power level by adjusting DC input voltage applied to an output stage of said RF amplifier based on the monitored electrical characteristic associated with said electrosurgical electrode;
a patient box coupled between said RF generator and said electrosurgical electrode to facilitate delivery of said RF signal from said RF electrosurgical generator to said electrosurgical electrode by way of said patient box, said patient box and said electrosurgical generator disposed in separate housings; and
a common mode choke in said patient box, said common mode choke including an output winding and a return winding, each of said output winding and said return winding being wound about a ferrite core, said output winding and said return winding spaced apart and in parallel to maintain a desired impedance, said output winding comprising a wire carrying said RF signal and said return winding comprising a duality of intertwined wires, each of said output winding and said return winding including adjacent ribs spaced apart,
said RF signal containing a common mode signal that is blocked by said common mode choke.
2. The system of claim 1 wherein said patient box has a transformer, and further comprising a balanced and symmetrical shielded transmission line coupling said electrosurgical generator to the transformer of said patient box.