Various high-strength microwave antenna assemblies are described herein. The microwave antenna has a radiating portion connected by a feedline to a power generating source, e.g., a generator. The antenna is a dipole antenna with the distal end of the radiating portion being tapered and terminating at a tip to allow for direct insertion into tissue. Antenna rigidity comes from placing distal and proximal radiating portions in a pre-stressed state, assembling them via threaded or overlapping joints, or fixedly attaching an inner conductor to the distal portion. The inner conductor is affixed to the distal portion by, e.g., welding, brazing, soldering, or by adhesives. A junction member made from a hard dielectric material, e.g., ceramic, can be placed between the two portions and can have uniform or non-uniform shapes to accommodate varying antenna designs. Electrical chokes may also be used to contain returning currents to the distal end of the antenna.

A surgical snare comprising a means of delivering thermal plasma on to biological tissue encircled by the snare. The snare may be cold snare, i.e. formed from insulating material, or active, i.e. connected to receive RF and/or microwave energy to be radiated into the area encircled by the snare. The surgical snare may thus deliver into biological tissue encircled by a retractable loop any one of (i) a plasma to perform surface coagulation, (ii) a non-ionising microwave field (in the absence of plasma) to perform coagulation at a deeper level, and (iii) an RF field to assist with cutting.

Examples of a water-cooled microwave ablation probe are disclosed. The probe comprises a feed cable and an antenna with a radiator, a reflector and a dielectric material therein between. An outer sheath with a flexible tubular body encases the feed cable and portion of the antenna. A front-end of the outer sheath is connected to the antenna such that the radiating head extends out of the outer sheath. The outer sheath is bonded to a rear section of the radiator and portion of the reflector defining a coaxial tuning cavity of the antenna. A flexible elongated water tube is coaxially inserted in the outer sheath forming an inlet channel in the water tube and outlet channel in the space between the water tube and the outer sheath. The cooling water circulates in the probe cavity cooling down the feed cable and the reflector.

A microwave ablation electrode is provided. The microwave ablation electrode mainly comprises a main needle body. A working end of the main needle body can release microwave energy to realize microwave ablation. A non-working end circulation cooling structure and a working end liquid injection structure are arranged on the main needle body, wherein the non-working end circulation cooling structure can allow a refrigerant medium to reach a front end of a non-working end of the main needle body to cool the non-working end of the main needle body and the surrounding tissues, and the non-working end circulation cooling structure can allow the refrigerant medium to flow back. The working end liquid injection structure can allow the refrigerant medium to reach the working end of the main needle body to cool the working end and the surrounding tissues, and can also allow the refrigerant medium to be injected into the lesion tissues and absorb microwave energy to form steam, so that steam thermal ablation is realized. Dual ablation of steam thermal ablation and microwave ablation is realized, the ablation effect is improved, the temperature of the working end of the microwave ablation electrode is reduced, the wettability of the surrounding tissues at the working end is increased, and the carbonization of the lesion tissues is reduced.

Various embodiments provide an electrosurgical instrument comprising: a flexible coaxial transmission line arranged to convey microwave energy; a radiating tip portion connected at a distal end of the flexible coaxial transmission line and configured to receive the microwave energy, the radiating tip portion comprising: a distal coaxial transmission line for conveying the microwave energy; and a needle tip mounted at a distal end of the distal coaxial transmission line, the needle tip being arranged to deliver the microwave energy into biological tissue; and a heat sink mounted at an interface between the flexible coaxial transmission line and radiating tip portion. The heat sink is in thermal communication with a proximal end of the distal coaxial transmission line and configured to draw thermal energy from the radiating tip portion. Also, a maximum outer diameter of the radiating tip portion is smaller than an outer diameter of the flexible coaxial transmission line. An associated electrosurgical system is also disclosed.

Examples of a water-cooled microwave ablation probe are disclosed. The probe comprises a feed cable and an antenna with a radiator, a reflector and a dielectric material therein between. An outer sheath with a flexible tubular body encases the feed cable and portion of the antenna. A front-end of the outer sheath is connected to the antenna such that the radiating head extends out of the outer sheath. The outer sheath is bonded to a rear section of the radiator and portion of the reflector defining a coaxial tuning cavity of the antenna. A flexible elongated water tube is coaxially inserted in the outer sheath forming an inlet channel in the water tube and outlet channel in the space between the water tube and the outer sheath. The cooling water circulates in the probe cavity cooling down the feed cable and the reflector.

A microwave ablation electrode is provided. The microwave ablation electrode mainly comprises a main needle body. A working end of the main needle body can release microwave energy to realize microwave ablation. A non-working end circulation cooling structure and a working end liquid injection structure are arranged on the main needle body, wherein the non-working end circulation cooling structure can allow a refrigerant medium to reach a front end of a non-working end of the main needle body to cool the non-working end of the main needle body and the surrounding tissues, and the non-working end circulation cooling structure can allow the refrigerant medium to flow back. The working end liquid injection structure can allow the refrigerant medium to reach the working end of the main needle body to cool the working end and the surrounding tissues.