Combined Frequency Microwave Ablation System, Devices and Methods of Use
A system for delivering electrosurgical energy, the system including a housing having an antenna attached to the distal end thereof configured to receive a microwave signal and radiate energy at two or more wavelengths and a microwave generator operably connecting to the antenna that provides the microwave signal to the antenna. The microwave generator generates a combined microwave signal containing microwave energy having at least a first and a second wavelength wherein the first and second wavelengths resonant the antenna.
1 . A method for delivering electrosurgical energy to tissue, the method comprising the steps of:
providing a di-pole microwave antenna attached to a distal end of a microwave energy transmission line, the di-pole microwave antenna including:
a proximal and distal radiating portions configured to resonate at at least two microwave frequencies;
positioning the di-pole microwave antenna relative to target tissue;
connecting a microwave generator to a proximal end of the microwave energy transmission line, the microwave generator configured to generate a microwave signal containing energy at the at least two microwave frequencies;
generating the microwave signal; and
delivering the microwave signal through the microwave energy transmission line and to the di-pole microwave antenna wherein the microwave signal resonates the di-pole microwave antenna at the at least two microwave frequencies.
2 . The method according to claim 1 , wherein the generating step includes the steps of:
generating a first microwave signal at a first frequency;
generating a second microwave signal at a second frequency; and
combining the first and second microwave signals.
3 . The method according to claim 2 , wherein the second frequency is approximately equal to a resonant frequency of the first frequency.
4 . The method according to claim 2 , further including the step of:
phase shifting the first frequency about 180° relative to the second frequency.
5 . The method according to claim 2 , wherein combining the first and second microwave signals increases energy penetration into tissue.
6 . The method according to claim 2 , further including the step of:
adjusting an intermixing ratio between the first and second microwave signals.
7 . The method according to claim 1 , further including the step of:
generating a current density that exhibits at least two null currents along the di-pole microwave antenna.
8 . The method according to claim 7 , wherein a first null current of the at least two null currents is positioned at the proximal end of the proximal radiating portion of the di-pole microwave antenna and a second null current of the at least two null currents is positioned at the distal end of the distal radiating portion of the di-pole microwave antenna.
9 . A method of increasing the penetration of microwave energy into a target tissue comprising the steps of:
positioning a di-pole microwave antenna relative to target tissue;
connecting a microwave generator to the di-pole microwave antenna, the microwave generator configured to generate a microwave signal containing energy at at least two microwave frequencies;
delivering the microwave signal to the di-pole microwave antenna;
modifying at least one of phase angle, frequency and intermixing ratio between the energy at the at least two microwave frequencies; and
resonating the di-pole microwave antenna at the at least two microwave frequencies.
10 . The method according to claim 9 , wherein the phase angle is modified by shifting the phase relationship between the at least two microwave frequencies by about 180°.
11 . The method according to claim 9 , wherein the intermixing ratio modifies the energy at the at least two microwave frequencies to a ratio between about 99:1 and 1:99.
12 . The method according to claim 9 , wherein at least one of the at least two microwave frequencies is modified to alter the current density pattern generated by the microwave antenna.
13 . The method according to claim 9 , further including the step of:
generating a current density that exhibits at least two null currents along the di-pole microwave antenna.
14 . The method according to claim 9 , wherein a first null current of the at least two null currents is positioned at the proximal end of the di-pole microwave antenna and a second null current of the at least two null currents is positioned at the distal end of the di-pole microwave antenna.