Dual antenna microwave resection and ablation device, system and method of use

The present disclosure relates to systems, devices and methods for performing medical procedures. More specifically, the present disclosure relates to dual-antenna microwave ablation and ablation devices and their use for treating tissue.

In the treatment of diseases such as cancer, certain cancer cells have been found to denature at temperatures slightly lower than the temperatures normally harmful to healthy cells. This type of treatment, commonly known as hyperthermia, typically heats abnormal cells to temperatures above 41 ° C, while maintaining adjacent healthy cells at a lower temperature that does not cause irreversible cell destruction. Use electromagnetic radiation to do this. Other procedures that utilize electromagnetic radiation to heat tissue include cauterization and coagulation of tissue. For example, such microwave ablation procedures, such as those performed for menorrhagia, are typically performed to cauterize and coagulate the target tissue to denature or kill the tissue. Many procedures and many types of devices that utilize electromagnetic radiation therapy are known in the art. Such microwave therapy is typically used in the treatment of tissues and organs such as the prostate, heart, liver, lungs, kidneys and breasts.

Currently, several types of microwave probes such as monopole type, dipole type and helical type are used. A monopole antenna probe consists of a single elongated microwave conductor exposed at the end of the probe. The probe is typically surrounded by a dielectric sleeve. A dipole antenna is composed of a coaxial structure having an inner conductor and an outer conductor in a state where a part of the inner conductor is separated by a dielectric joint. The inner conductor may be connected to a portion corresponding to the first dipole radiating portion, and a part of the outer conductor may be connected to a second dipole radiating portion. The dipole radiating portion may be configured such that one radiating portion is located proximal to the dielectric junction and the other radiating portion is located distal to the dielectric junction. In monopole and dipole antenna probes, microwave energy is generally radiated vertically from the axis of the conductor.

A typical microwave antenna has a long, thin inner conductor that extends along the axis of the probe, is surrounded by a dielectric, and is further surrounded by an outer conductor that surrounds the dielectric. As a result, the outer conductor also extends along the axis of the probe.

In the case of tissue ablation, a high frequency current in the range of about 500 MHz to about 10 GHz is applied to the target tissue site to generate a cauterized volume that can have a specific size and shape. Cauterized volume correlates with antenna design, antenna performance, antenna impedance and tissue impedance. A particular ablation volume may be determined in response to a particular type of tissue ablation procedure to achieve the desired surgical result. By way of example, but not limited to, spinal cord ablation may require a longer and thinner ablation volume, and prostate ablation may require a more spherical ablation volume.

One particular ablation procedure is a tissue resection procedure. In a tissue resection procedure, the clinician first determines the need for resection or removal of that portion of a particular organ, including pathological tissue. When cauterizing tissue along the excision line, the pathological and healthy tissue on the organ can be removed while leaving a sufficient portion of the organ to survive and function. Position the excision line in between.

One step in microwave ablation or ablation is the placement of one or more microwave energy transfer devices in a portion of the target tissue. Proper placement is generated by the size and shape of the desired ablation region, the type of ablation device used, the parameters of the microwave energy signal (ie, frequency, power, duty cycle, etc.) and the ablation device. The placement process is an important process as it often depends on several factors, such as the expected cauterization size that can occur.

If the procedure requires multiple ablation devices, the placement process becomes even more complex. For example, excision procedures that require ablation of tissue along a given excision line often require the placement of multiple microwave energy transfer devices along a particular excision line. One particular placement method includes the insertion of multiple tissue-penetrating microwave energy transfer devices that are placed within the target tissue by percutaneous insertion.

In the resection procedure, the clinician determines the location of the resection line and then the placement of a cauterizing device that cauterizes the tissue along the resection line. This arrangement is typically determined by the size and shape of the ablation area expected for one or more selected ablation devices. In most excision procedures, multiple cauterizing devices are placed along the excision line to transfer sufficient energy to achieve complete ablation of the tissue along the excision line.

In one known method of excision and ablation, the first ablation is performed along the excision line, and the ablation device is moved to the next position along the excision line to perform the next ablation. This process is repeated along the excision line until the entire excision line is cauterized. In another method of excision, multiple cauterizing devices are inserted along the excision line and energy is supplied to the devices at the same time (or at about the same time) to cauterize the tissue along the excision line. Both methods are effective, but the first method is time consuming because multiple cauterizations are performed in sequence. The second method requires accurate placement of multiple devices to ensure complete cauterization while minimizing interaction or interference between adjacent devices.

Regardless of the method used, the resection procedure is complex because the desired ablation area for a typical ablation procedure is very different in shape and size from the desired ablation area for a typical ablation procedure. The target tissue in the ablation procedure is typically a round, oval or oblong neoplastic mass. Therefore, microwave ablation devices are typically designed to produce round, oblong or oval ablation regions. In contrast to the ablation procedure, the excision procedure typically requires ablation of an elongated area of tissue along the excision line, and the length of the ablation area in the excision procedure is usually produced by a typical ablation device. Much larger than the width and / or thickness of the cauterized area.

Differences in the shape of the desired ablation region are problematic, as clinicians typically use the same ablation device for ablation and resection procedures.

The present disclosure describes a dual-antenna microwave ablation and ablation device configured to produce a cautery region of the desired size and size for ablation and ablation procedures.

One embodiment of the present disclosure relates to a microwave energy generation system having a transmission line connected to a microwave generator and a dual antenna microwave device. The microwave generator produces a first microwave signal and a second microwave signal transmitted by the transmission line to the dual antenna microwave device. The dual-antenna microwave device includes a first antenna, a second antenna distal to the first antenna, and a double-sided choke located between the first and second antennas. The first antenna receives the first microwave frequency signal from the transmission line between the first conductor and the second conductor of the transmission line, and the second antenna is the second conductor of the transmission line and Receives a second microwave frequency signal from the third conductor. The double-sided choke includes a choke conductor that further includes a first antenna choke circuit and a second antenna choke circuit. The first antenna choke circuit is configured to limit the propagation of the electromagnetic field generated by the first antenna to the second antenna, and the second antenna choke circuit is generated by the second antenna. It is configured to limit the propagation of the electromagnetic field to the first antenna. In one embodiment, the choke conductor is electrically connected to the second conductor.

The length of the first antenna, the second antenna and / or the double-sided choke may correspond to 1/4 wavelength of the first microwave frequency signal and / or the second microwave frequency signal. The first antenna may be configured to emit the first microwave frequency signal and the second antenna may emit the second microwave frequency signal at the same time. The dielectric coating may be at least partially located on the first antenna, the second antenna and / or the double-sided choke.

The first antenna may further include a distal radiating portion, the second antenna may further include a proximal radiating portion, and the first and second antennas may include a first antenna. An electromagnetic field is generated between the distal radiating part of the antenna and the proximal radiating part of the second antenna. The proximal and distal radiators may have a length proportional to the effective wavelength of the radiation transmitted by the antenna assembly.

In a further embodiment, the dual antenna microwave device further includes a feed path having an inner conductor, an outer conductor and a triple coaxial conductor. At least a portion of the feed path includes an inner conductor, an outer conductor and a triple coaxial conductor in the triple coaxial direction.

The first antenna may further include a first feed point and the second antenna may further include a second feed point. The distance between the midpoint of the first feed point and the midpoint of the second feed point should be at least one quarter wavelength of the first microwave frequency signal and the second microwave frequency signal. It may be equivalent.

In a further embodiment, the length of the first antenna choke circuit and / or the second antenna choke circuit corresponds to 1/4 wavelength of the first microwave frequency signal and / or the second microwave frequency signal. May be.

Another embodiment of the present disclosure is a tissue ablation device comprising a transmission line, a first antenna, a second antenna and a double-sided choke. The second antenna is distal to the first antenna and the double-sided choke is located between the first and second antennas. The transmission line connects the device to a microwave energy source and transmits the first microwave frequency signal and the second microwave frequency signal from the microwave energy source to the first antenna and the second antenna. .. The first antenna receives the first microwave frequency signal between the first conductor and the second conductor of the transmission line, and the second antenna is the second conductor and the third conductor of the transmission line. Receives a second microwave frequency signal to and from the conductor. The double-sided choke includes a choke conductor that further includes a first antenna choke circuit and a second antenna choke circuit. The first antenna choke circuit is configured to limit the propagation of the electromagnetic field generated by the first antenna to the second antenna, and the second antenna choke circuit is generated by the second antenna. It is configured to limit the propagation of the electromagnetic field to the first antenna.

Yet another embodiment of the present disclosure relates to a microwave antenna assembly for performing microwave energy therapy, each comprising a proximal portion having an inner conductor, an outer conductor and a triple coaxial conductor extending into it. The assembly also includes a first antenna, a second antenna and a double-sided choke. In the proximal region, the inner conductor is located within the outer conductor and the outer conductor is located within the triple coaxial conductor. The first antenna includes a first antenna distal radiator connected to a triple coaxial conductor and a first antenna proximal radiator connected to an outer conductor. The second antenna includes a second antenna distal radiator connected to the inner conductor and a second antenna proximal radiator connected to the inner conductor. A double-sided choke having at least a portion arranged between the first antenna and the second antenna with them includes a first antenna choke circuit and a second antenna choke circuit. The first antenna choke circuit is configured to limit the propagation of the electromagnetic field generated by the first antenna to the second antenna, and the second antenna choke circuit is generated by the second antenna. It is configured to limit the propagation of the electromagnetic field to the first antenna.

<figref num="1A">It is the schematic of the microwave energy transfer system including the dual antenna microwave excision and ablation device (DAMRAD) which concerns on one Embodiment of this disclosure.</figref><figref num="1B">A microwave including a first microwave signal generator and a second microwave signal generator that provide a first microwave energy signal and a second microwave energy signal to DAMRAD according to another embodiment of the present disclosure. It is a schematic diagram of an energy transfer system.</figref><figref num="2">It is a graphic diagram of the simulated power flow generated by the distal antenna of DAMRAD.</figref><figref num="3">It is a graphic diagram of the simulated power flow generated by the proximal antenna of DAMRAD.</figref><figref num="4">It is a graphic diagram of the simulated power flow generated by the distal antenna and the proximal antenna of DAMRAD.</figref><figref num="5">It is sectional drawing of the antenna part of DAMRAD.</figref><figref num="6">It is sectional drawing of the distal antenna of DAMRAD.</figref><figref num="7">It is sectional drawing of the proximal antenna of DAMRAD.</figref><figref num="8">It is sectional drawing of the double-sided choke of DAMRAD which concerns on another embodiment of this disclosure.</figref><figref num="9">FIG. 5 is a cross-sectional view of a DAM RAD double-sided choke according to yet another embodiment of the present disclosure.</figref>

Although detailed embodiments of the present disclosure will be described herein, it should be understood that the disclosed embodiments are merely examples and can be embodied in various forms. Accordingly, detailed descriptions of the specific structures and functions disclosed herein are not limiting, but merely as a basis for claims and in substantially any reasonably detailed structure. Should be interpreted as a representative basis for teaching those skilled in the art to use in various ways.

Referring to FIG. 1A, a microwave including a microwave generator 100, a dual antenna microwave ablation and ablation device (DAMRAD) 110 using the embodiments of the present disclosure, and a triple coaxial transmission cable 120 connected between them. The energy transfer system 10 is shown. The triple coaxial transmission cable 120 may be permanently attached to the DAMRAD 110 (as shown in FIG. 1A), or the triple coaxial transmission cable 120 may be separate from the DAMRAD 110. Alternatively, the DAMRAD110 may be connected to a plurality of coaxial transmission cables (not shown), each of which provides a microwave energy signal to the DAMRAD110. The microwave energy signals provided to the triple coaxial transmission cable 120 or the plurality of coaxial transmission cables may be in phase or out of phase with each other. In one embodiment, the microwave generator 100 is a microwave signal distributor configured to split a single microwave energy signal generated by the microwave generator 100 into two signals for the DAMRAD 110. (Not shown) may be further included.

As shown in FIG. 1A, DAMRAD110 includes a percutaneous device with a sharp tip 118 configured to penetrate tissue. The antenna portion 116 includes a proximal antenna 116a and a distal antenna 116b separated by a double-sided choke 128. The handle 112 is connected to the antenna portion 116 by a long shaft 114.

The elongated shaft 114 is configured to provide microwave energy signals to the proximal antenna 116a and the distal antenna 116b, respectively. In one embodiment, the elongated shaft 114 includes three conductors arranged in a triple coaxial configuration, thereby forming a triple coaxial transmission line. Alternatively, the elongated shaft 114 may include a plurality of transmission lines, each of which supplies a microwave energy signal to one of the antennas 116a and 116b.

The microwave generator 100 is configured to provide a suitable microwave energy signal for the DAMRAD110. The microwave energy signals may be substantially the same or related in one or more ways (eg, in-phase, similar frequencies and / or power levels). For example, the microwave generator 100 provides a phase shift circuit (not shown) configured to offset the first and second microwave signals by a predetermined microwave frequency with a selected phase shift. It may be included. The selected phase shift may be determined by the clinician according to the physical properties or configuration of the DAMRAD116, or may be selected based on the feedback (ie, reflected energy) measured by the microwave generator 100.

The microwave generator also generates a first microwave signal with a first frequency and a second microwave signal with a second frequency (here, what are the first and second frequencies? It may include a first microwave signal generation circuit (different) and a second microwave signal generation circuit (not shown). In one embodiment, the first frequency and the second frequency are harmonics.

Referring to FIG. 1B, a microwave energy transfer system 11 with a first microwave generator 100a and a second microwave generator 100b connected to the DAMRAD 100 via a coaxial-triple coaxial connector 105 is shown. .. The first microwave generator 100a produces a first microwave energy signal and the second microwave generator 100b produces a second microwave signal. The first microwave signal and the second microwave signal are the first coaxial cable 120a connected to the first coaxial connector 105a and the second coaxial cable 120b connected to the second coaxial connector 105b. Provided to the coaxial-triple coaxial connector 105 via each. The triple coaxial connector 105 transmits the first microwave energy signal and the second microwave energy signal to the triple coaxial cable 120 connected to the DAMRAD 100. The first microwave generator 100a and the second microwave generator 100b are connected to each other by a microwave generator interface cable 107 to provide control and / or synchronization information between them.

Even if the first microwave signal generated by the first microwave generator 100a and the second microwave signal generated by the second microwave generator 100b are substantially the same, They may be related in one or more ways (eg, in-phase, similar frequencies and / or power levels). For example, the first microwave signal generated by the first microwave generator 100a may be phase-shifted with respect to the second microwave signal generated by the second microwave generator 100b. .. The microwave generator interface cable 107 may provide one or more parameters for one of the first or second microwave signals. For example, the microwave generator interface cable 107 may provide signal phase data, timing signal or frequency data between the first generator 100a and the second generator 100b. The microwave interface cable 107 may provide a sample of one of the first and / or second microwave signals or a signal relating thereto.

The phase shift between the first microwave signal and the second microwave signal may be determined by the clinician by the physical properties or configuration of the DAMRAD116, or measured by the microwave generator 100. It may be selected based on the feedback (ie, reflected energy).

The DAMRAD may be designed to operate at microwave frequencies of 915MHz, 2.45GHz or any other suitable frequency. DAMRADs designed to operate at 915MHz include longer antenna lengths (because of longer wavelengths) compared to DAMRADs designed to operate at 2.45GHz, and are therefore described below. Produces a longer cautery area.

The energy associated with the field generated by the microwave antenna may be expressed as the electric field strength (hereinafter, E field) or the magnetic field strength (hereinafter, H field), and each strength is as effective as the radiant energy flow. Formula is obtained. The simulated power flows 236, 336, and 436 in FIGS. 2 to 4 show the power flow as the product of the E field (unit: V / m) and the H field (unit: A / m), and here, E. The unit of the product of the field and the H field is VA / m²Will be. The simulations in FIGS. 2-4 use the 0.915 GHz microwave energy signals provided to the distal antenna 116b in FIG. 2, the proximal antenna 116a in FIG. 3, and the proximal antenna 116a and the distal antenna 116b in FIG. I went.

The simulated power flows 236, 336, and 436 are shown as three different regions of the power flow for clarity. For example, as shown in FIG. 2, the simulated power flow 236 includes a region of high density power flow 236a, a region of medium density power flow 236b and a region of low density power flow 236c. The actual power flow and / or the simulated power flow 236, 336, 436 includes a power flow gradient in which the absolute value of the power flow 236 decreases proportionally (linearly, non-linearly, or exponentially). It is understood that it may be related to the distance from the distal antenna 116b.

FIG. 2 is a graphic diagram of the simulated power flow 236 generated by the distal antenna 116b of the DAMRAD110 (DAMRAD110 is overlaid on top of the graphic diagram for illustration purposes). The DAMRAD110 includes a distal antenna 116b and a proximal antenna 116a separated by a double-sided choke 128. The simulation was performed using the 915 MHz microwave energy signal provided to the distal antenna 216b. The proximal portion 236d of the power flow 236 is shorted by the distal side of the double-sided choke 128, as described below.

FIG. 3 is a graphic diagram of the simulated power flow generated by the DAM RAD110 proximal antenna 116a (DAMRAD110 is overlaid on top of the graphic diagram for illustration purposes). For clarity, the simulated power flow 336 is shown to include a region of high density power flow 336a, a region of medium density power flow 336b and a region of low density power flow 336c. The distal portion 336e of the power flow 336 is shorted by the proximal side of the double-sided choke 128, as described below. Since no choke is provided on the proximal side of the proximal antenna 116a, the proximal portion 336f of the power flow 336 extends beyond the proximal end of the proximal antenna 116a.

FIG. 4 is a graphic diagram of a simulation of the combined power flow 436 generated by the distal 116b antenna and the proximal antenna 116a of the DAMRAD110 (DAMRAD110 is overlaid on top of the graphic diagram for illustration). .. The simulated power flow 436 includes a region of high density power flow 436a, a region of medium density power flow 436b and a region of low density power flow 436c. The double-sided choke 128 shunts the magnetic field generated proximal to the distal antenna 116b and shunts the magnetic field generated distal to the proximal antenna 116a. Therefore, in the region adjacent to the double-sided choke 128, there is almost no interaction between the magnetic fields generated by either the antennas 116a or 116b. Since no choke is provided on the proximal side of the proximal antenna 116a, the proximal portion 436f of the power flow 436 extends beyond the proximal end of the proximal antenna 116a.

The region adjacent to and / or the surrounding region of the DAMRAD110 double-sided choke 128 receives energy from the electromagnetic field generated by the distal antenna 116b and the electromagnetic field generated by the proximal antenna 116a, thereby synergizing this region. Heating effect is produced. Figures 2-4 show that the DAMRAD110 is configured to generate an elongated region of high density power flow 436a that extends from the distal tip 118 of the DAMRAD110 to the proximal point of the proximal antenna 116a. It can be confirmed from the simulated power flow 236, 336, 436. Therefore, the effective length of the cauterized region that can be generated from the DAMRAD110 is at least 2 to 3 times as long as the cauterized region produced from a microwave energy transfer device that includes a single antenna.

Surrounding the double-sided choke 128 by simultaneously transmitting energy to the dual antennas 116a, 116b, or by alternately transmitting microwave energy signals between the proximal antenna 116a, the distal antenna 116b, or any combination thereof. A synergistic heating effect may be obtained on the region. As described below, and as shown in FIG. 1, in at least one embodiment, the microwave signals provided to the proximal antenna 116a and the distal antenna 116b are the same microwave generator 100 and triple coaxial transmission cable. Provided from 120. Thus, the microwave signals provided to the proximal antenna 116a and the distal antenna 116b share substantially the same supply path and distance. Therefore, the microwave energy signals provided to the two antennas 116a, 116b are essentially homeomorphic to each other.

As shown in FIGS. 2-4, the DAMRAD110 is configured to generate ablation regions of different sizes and shapes. The DAMRAD110 may be used in the same manner as a standard cauterizer by utilizing only one of the dipole antennas 116a, 116b and supplying energy to it. Alternatively, in another embodiment, the distal antenna 116b may be utilized to generate a typical cauterized region, and the proximal antenna 116a may be utilized to selectively cauterize at least part of the insertion path. You may. Finally, as shown in FIG. 4, DAMRAD110 is configured to produce an elongated cauterized region with a shape that is particularly suitable for excision procedures.

FIG. 5 is a cross-sectional view of the antenna portion 116 of the DAMRAD 110 of FIG. The antenna portion 116 includes a proximal antenna 116a and a distal antenna 116b separated by a double-sided choke 128. Distal to the distal antenna 116b is a sharp tip 118 configured to facilitate percutaneous insertion of DAMRAD110 into patient tissue (not shown). The distal antenna 116b, the proximal antenna 116a and the double-sided choke 128 are further shown in FIGS. 6, 7 and 8, respectively, and are described in detail below.

FIG. 6 is a cross-sectional view of the distal antenna 116b of the DAMRAD 110 of FIG. The distal antenna 116b is configured as a dipole antenna and includes the distal antenna distal radiator 117 and the distal antenna proximal radiator 115, both of which are distal at the distal end of the inner coaxial cable 120a. Receives the microwave energy signal from the antenna feeding point 119b. The inner coaxial cable 120a includes an inner conductor 121 and an outer conductor 123 in a coaxial arrangement and is separated by an inner dielectric 122 to provide a microwave energy signal to the distal antenna feeding point 119b.

The distal antenna 116b may be at least partially surrounded by a dielectric loading sleeve 141. The dielectric loading sleeve 141 is configured to insulate various parts of the distal antenna 116b from surrounding tissue (not shown) and provide a uniform diameter between the distal antenna 116b and the rest of the DAMRAD 110. ing. The dielectric loading sleeve 141 may also provide a buffer (ie, dielectric buffer) between the distal antenna 116b and the variable load of surrounding tissue (not shown). The distal antenna 116b may be inserted into the dielectric loading sleeve 141, or the dielectric loading sleeve 141 may be a distal antenna by various methods such as injection or by shrink packaging methods commonly used in the art. It may be formed around 116b.

FIG. 7 is a cross-sectional view of the proximal antenna 116a of the DAMRAD 110 of FIG. The proximal antenna 116a is configured as a dipole antenna and includes the proximal antenna distal radiation section 137 and the proximal antenna proximal radiation section 138, both of which are proximal to the distal end of the outer coaxial cable 120b. Receives the microwave energy signal from the antenna feeding point 119a. The outer coaxial cable 120b of the triple coaxial transmission cable 120 includes an outer conductor 123 and a triple coaxial conductor 125 in a coaxial arrangement and is separated by an outer dielectric 124. The outer coaxial cable 120b provides a microwave energy signal to the proximal antenna feeding point 119a.

With reference to FIGS. 6 and 7, the outer conductors 123, 123 are common to the inner coaxial cable 120a and the outer coaxial cable 120b. An inner conductor 121, an outer conductor 123, and a triple coaxial conductor 125 are arranged in a triple coaxial configuration in the proximal position of the proximal antenna 116a. The inner conductor 121 and the outer conductor 123 are separated by the inner dielectric 122, and the outer conductor 123 and the triple coaxial conductor 125 are separated by the outer dielectric 124, which together form the triple coaxial transmission cable 120. doing.

The triple coaxial transmission cable 120 supplies microwave energy signals to the proximal antenna 116a and the distal antenna 116b. Due to the configuration of the triple coaxial transmission cable 120, the distance of the feeding path (for example, the physical distance of the cable between the microwave generator 100 in FIG. 1 and the proximal antenna feeding point 119a in FIG. 7) is both microwave signals. Can be the same for. Therefore, the microwave signals provided by the inner conductor 120a and the outer conductor 120b undergo substantially the same phase shift caused by the length of the transmission line of the microwave signal.

Referring to FIGS. 5-7, the distal antenna proximal radiating section 115 and the proximal antenna distal radiating section 137 are connected to the outer conductor 123 of the triple coaxial power supply path 120. Referring to FIGS. 6 and 7, the proximal antenna feeding point 119a and the distal antenna feeding point 119b are offset by a certain distance, and the distance between the feeding points 119a and 119b is the wavelength of a predetermined microwave frequency or It corresponds to the fractional part (that is, 1/4 wavelength, 1/2 wavelength). This distance may be optimized and / or configured by the DAMRAD110 to achieve a long, narrow ablation area.

Also, as shown in FIG. 5, a ferrite ring 179 is placed on the proximal long shaft 114 of the proximal antenna 116a to limit the intensity of microwave energy proximal to the proximal antenna 116a. You may. The ferrite ring 179 may be made of any suitable metal or conductive material capable of shunting electromagnetic energy proximally radiated from the antenna 116. Further, the ferrite ring 179 may be configured as a Faraday shield, or may be configured to shunt electromagnetic energy proximally radiated from the antenna at a predetermined microwave frequency.

Returning to FIG. 7, the distal radiation portion of the proximal antenna 137 is at least partially surrounded by the proximal dielectric loading sleeve 140. The proximal dielectric loading sleeve 140 may be connected to, or part of, the outer jacket 126, the distal dielectric loading sleeve 141 (see FIG. 6), or both.

FIG. 8 is a cross-sectional view of the double-sided choke 128 of the DAM RAD 110 of FIG. 1 according to another embodiment of the present disclosure. The double-sided choke 128 includes a choke conductor 129 that is electrically connected to the outer conductor 123. In one embodiment, at least a portion of the choke conductor 129 partially surrounds a portion of the proximal antenna choke extension dielectric 142 and / or the distal antenna choke extension dielectric 143. The distal antenna choke circuit 128b is formed between the outer conductor 123 and the first segment 129a of the choke conductor 129 with the opening of the distal antenna choke circuit 128b oriented towards the distal antenna 116b. ing. The proximal antenna choke circuit 128a is formed between the first segment 129a and the second segment 129b of the choke conductor 129, and the opening of the proximal antenna choke circuit 128a is in the direction of the proximal antenna 116a. It is aimed. At the termination point 119 of the double-sided choke, the choke conductor 129 is connected to the outer conductor 123, forming a suitable electrical connection. The electrical connection may be a solder connection, a weld, a press-fit connection or any other suitable connection. The outer surface of the double-sided choke 128 is coated with a dielectric loading sleeve 140, which is the outer jacket (see outer jacket 127 in FIG. 7) and the distal dielectric loading sleeve (dielectric in FIG. 6). It may be connected to or formed from the loading sleeve 141) or both. The double-sided choke 128 may be used with a ferrite ring (see Ferrite ring 179 located on the long shaft 114 proximal to the proximal antenna 116a in FIG. 5).

Proximal antenna choke circuits 128a and distal antenna choke circuits 128b may be configured as shorted chokes of 1/4 wavelength to limit microwave energy intensification beyond antennas 116a, 116b. You may support.

In another embodiment, the double-sided choke 128 of FIG. 8 may be replaced with a double-sided choke 928, as shown in FIG. The double-sided choke 928 includes a proximal antenna choke circuit 928a and a distal antenna choke circuit 928b. The proximal antenna choke circuit 928a includes a proximal choke segment 929a that electrically connects to the outer conductor 123 via a common choke conductor 929. The proximal antenna choke circuit 928a may at least partially surround the proximal antenna choke extension dielectric 942. The distal antenna choke circuit 928b includes a distal choke segment 929b that electrically connects to the outer conductor 123 via a common choke conductor 929. The distal antenna choke circuit 928b may at least partially surround the distal antenna choke extension dielectric 943. As shown in FIG. 9, both the proximal antenna choke circuit 928a and the distal antenna choke circuit 928b are connected to the outer conductor via a common choke conductor 929. In another embodiment, each choke circuit 928a, 928b may be provided with a separate connection with the outer conductor 123. The outer surface of the double-sided choke 928 is coated with a dielectric loading sleeve 940, which is the outer jacket (see outer jacket 126 in FIG. 7) and the distal dielectric loading sleeve (distal in FIG. 6). It may be connected to or formed from the dielectric loading sleeve 141) or both. The double-sided choke 928 may be used with a ferrite ring (see Ferrite ring 179 located on the long shaft 114 proximal to the proximal antenna 116a in FIG. 5).

With reference to FIGS. 8 and 9, the longitudinal length of the double-sided choke 128 is shorter than the longitudinal length of the double-sided choke 928. Therefore, the distances between the proximal antennas 116a, 916a and the distal antennas 116b, 916b on the device with the double-sided choke 128 and the double-sided choke 928 are different, respectively. The distance between the proximal antennas 116a, 916a and the distal antennas 116b, 916b affects the phase relationship between the microwave energies radiated from the proximal antennas 116a, 916a and the distal antennas 116b, 916b. Therefore, a device with a double-sided choke 128 provides a different phase relationship between the microwave energies radiated from the proximal antenna 116a and the distal antenna 116b than a device with a double-sided choke 928.

Continuing with reference to FIGS. 8 and 9, the double-sided choke configuration places one choke radially outward from the other choke, while the double-sided choke 928 places the chokes 928a, 928b on substantially the same radial plane. Therefore, the overall diameter of the antenna 916 may be reduced by a device equipped with a double-sided choke 928.

Although various modifications of the above configuration are possible without departing from the scope of the present disclosure, all matters contained in the above description should be construed as an example rather than a limitation. It will be found that some of the objects of the present disclosure are achieved and favorable results are achieved, as defined by the claims below.