Systems and methods for tissue ablation and measurements relating to the same

A system for ablating target tissue within a patient, the system comprising:

• a catheter having a proximal region and a distal region;
• a switching antenna disposed at the distal region of the catheter, the switching antenna comprising a main antenna comprising a proximal radiating element, a distal radiating element, and a microwave choke arranged at a proximal end of the proximal radiating element configured to minimize fold back of a radiating field pattern along the main antenna, the main antenna configured to switch between emitting energy to ablate the target tissue and measuring a radiometer temperature generated as a result of the energy emission with a radiometer, the switching antenna configured to convert from a dipole antenna to a monopole antenna by shorting a proximal-most end of the proximal radiating element to the main antenna with a short to defeat a choke action of the proximal radiating element;
• a reference termination disposed between the proximal radiating element and the distal radiating element, the reference termination comprising a temperature sensor configured to measure a reference temperature at the distal region;
• and
• a processor programmed to:
• perform a reference termination calibration to account for heating of the reference termination responsive to the energy emission via the main antenna and a radiometer calibration to account for heating of an environment adjacent the target tissue during the energy emission via the main antenna;
• and
• calculate a target tissue temperature based on the measured radiometer temperature and the measured reference temperature while accounting for heating of the reference termination and the environment adjacent the target tissue responsive to the energy emission via the main antenna.

A system for ablating target tissue within a patient, the system comprising:

• a catheter having a proximal region and a distal region;
• a switching antenna disposed at the distal region of the catheter, the switching antenna comprising a main antenna comprising a proximal radiating element, a distal radiating element, and a microwave choke arranged at a proximal end of the proximal radiating element configured to minimize fold back of a radiating field pattern along the main antenna, the main antenna configured to switch between emitting energy to ablate the target tissue and measuring a radiometer temperature generated as a result of the energy emission with a radiometer, the switching antenna configured to convert from a dipole antenna to a monopole antenna by shorting a proximal-most end of the proximal radiating element to the main antenna with a short to defeat a choke action of the proximal radiating element;
• a reference termination disposed between the proximal radiating element and the distal radiating element, the reference termination comprising a temperature sensor configured to measure a reference temperature at the distal region;
• a cooling sleeve disposed over at least the distal region of the catheter, the cooling sleeve coupled to a source of coolant and configured to permit the coolant to flow over the main antenna and the reference termination, thereby cooling the main antenna and the reference termination during pre-ablation calibration and during an ablation procedure;
• and
• a processor programmed to:
• apply a radiometer signal to the main antenna at a first known environment temperature and measure a first output voltage of the reference termination;
• apply the radiometer signal to the main antenna at a second known environment temperature and measure a second output voltage of the reference termination;
• compare the first and second output voltages with the first and second known environment temperatures to calibrate out an effect of the energy emission via the main antenna on an environment adjacent the main antenna;
• and
• calculate a target tissue temperature based on the measured radiometer temperature and the measured reference temperature while accounting for heating of the environment adjacent the target tissue during the energy emission via the main antenna,
• wherein the cooling sleeve is configured to cool the reference termination to maintain a constant temperature of the reference termination at both the first and second known environment temperatures.