Tissue impedance measurement using a secondary frequency

A method of ablating tissue using microwave energy, the method comprising the steps of:

• generating a microwave energy signal with a first energy source;
• generating a radio frequency (RF) energy signal with a second energy source;
• blocking the microwave energy signal from the second energy source and blocking the RF energy signal from the first energy source;
• generating a multiplexed energy signal by multiplexing the microwave energy signal and the RF energy signal and outputting the multiplexed energy signal to a tissue region;
• receiving a portion of the RF energy signal returned from the tissue region;
• measuring a voltage and current of the portion of the RF energy signal returned from the tissue region;
• calculating a tissue impedance based on the measured voltage and current, and
• displaying the calculated tissue impedance.

A method of controlling the output of a microwave ablation system, the method comprising the steps of:

• providing a microwave ablation system including:
• a generator with a first energy source, a second energy source and a diplexer, the diplexer operable to multiplex a first energy signal from the first energy source and a second energy signal from the second energy source into a multiplexed energy signal while blocking energy between the first and second energy sources, wherein said second energy source is a radio frequency (RF) generator;
• a cable including a center conductor and an outer sheath, the multiplexed energy signal being transmitted through said center conductor;
• an antenna operable to receive the multiplexed energy signal from said center conductor and to deliver the multiplexed energy signal to a region of tissue, wherein said outer sheath acts as a return path of said second energy signal to said second energy source;
• and
• a sensor operable to measure at least one parameter of said second energy signal transmitted from said return path;
• controlling an output level of the first energy signal based on the at least one measured parameter.

A method of controlling the output of a microwave ablation system, the method comprising the steps of:

• providing a microwave ablation system including:
• a generator including a first energy source, a second energy source and a diplexer, said diplexer operable to multiplex a first energy from said first energy source and a second energy from said second energy source into a multiplexed energy signal while blocking energy between the first and second energy sources, wherein said second energy source is a radio frequency (RF) generator;
• a cable including a center conductor and an outer sheath, the multiplexed energy signal being transmitted through said center conductor;
• an antenna operable to receive the multiplexed energy signal from said center conductor and to deliver the multiplexed energy signal to a region of tissue;
• a return pad operable to receive said second energy outputted from said antenna, said return pad transmits said second energy to said second energy source;
• and
• a sensor operable to measure at least one parameter of said second energy transmitted from said return pad;
• controlling an output level of the first energy based on the at least one measured parameter.