Patent Description:
Minimally invasive medical techniques are intended to reduce the amount of tissue that is damaged during medical procedures, thereby reducing patient recovery time, discomfort, and harmful side effects. Such minimally invasive techniques may be performed through natural orifices in a patient anatomy or through one or more surgical incisions. Through these natural orifices or incisions an operator may insert minimally invasive medical instruments (including surgical, diagnostic, therapeutic, or biopsy instruments) to reach a target tissue location. One such minimally invasive technique is to use a flexible and/or steerable elongate device, such as a flexible catheter, that can be inserted into anatomic passageways and navigated toward a region of interest within the patient anatomy.

Tissue ablation devices currently have few options for small form factors while preserving flexibility to navigate tortuous anatomy. It would be advantageous to provide materials and designs that support flexible navigation of antennas for tissue ablation that retain antenna shape, improve manufacturability, and/or facilitate control of tissue ablation parameters, and that are suitable for use during minimally invasive medical techniques.

<CIT> discloses microwave antennas and other energy delivery systems. It discloses systems and methods for the delivery of various medical components within or on a body for performing one or more medical procedures. The medical systems comprise a combination of one or more medical components and one or more elongate steerable or non-steerable arms that are adapted to mechanically manipulate the one or more medical components.

<CIT> discloses an energy applicator for directing energy to tissue. The applicator includes a feedline having an inner conductor, an outer conductor and a dielectric material disposed therebetween, and an antenna assembly having a radiating section operably coupled to the feedline. The energy applicator also includes a first balun structure configured to substantially confine energy to the radiating section when the energy applicator is energized and disposed in tissue, and a second balun structure configured to substantially prevent energy emitted from the radiating section from propagating proximal to the second balun structure along the feedline when the energy applicator is energized but not disposed in tissue.

<CIT> discloses an electrosurgical system including an electrosurgical device, one or more temperature sensors associated with the electrosurgical device, a fluid-flow path leading to the electrosurgical device, and a flow-control device disposed in fluid communication with the fluid-flow path. The electrosurgical device includes a probe for directing energy to tissue.

Further aspects and preferred embodiments of the invention are set out in the dependent claims.

It is to be understood that the following detailed description is exemplary and explanatory in nature and is intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure.

It will nevertheless be understood that no limitation of the scope of the disclosure is intended. In the following detailed description of the aspects of the invention, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, as would be appreciated by one skilled in the art, embodiments of this disclosure may be practiced without these specific details. In other instances well known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the embodiments of the invention.

Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In addition, dimensions provided herein are for specific examples and it is contemplated that different sizes, dimensions, and/or ratios may be utilized to implement the concepts of the present disclosure. To avoid needless descriptive repetition, one or more components or actions described in accordance with one illustrative embodiment may be used or omitted as applicable from other illustrative embodiments. For the sake of brevity, the numerous iterations of these combinations will not be described separately. For simplicity, in some instances the same reference numbers are used throughout the drawings to refer to the same or like parts.

Minimally invasive techniques may include the use of tissue ablation devices. Tissue ablation may be accomplished by electrical energy from frequencies ranging from very low frequency up to microwave and higher. However, for applications that rely upon an antenna to emit these frequencies into surrounding tissue, (i.e., accomplishing ablation by dielectric heating), difficulties may arise. For example, microwave antennas may be formed from coaxial cables comprising a conducting material (e.g., copper) that is relatively inflexible, particularly in the small sizes used for endoluminal applications. The rigidity of the conducting material may limit the utility of the antenna in anatomical regions that require traversal of one or more luminal bends to reach a region of interest. Though the antenna may bend at a curve in the lumen, the rigidity of the material may prevent the antenna from recovering from the bend when positioned at the target tissue to begin ablation. In other words, the antenna may be unable to re-straighten to its pre-bend form prior to performing the ablation on the target tissue. Additionally, most antennas are monopoles or dipoles where the length of the antenna is set by the frequency. It may be difficult to control the size of an ablation zone and minimum insertion depth of these antennas for tissue ablation, since the length of the antenna, and therefore the length of insertion (and ablation size) is dictated by the frequency of operation selected at manufacture for the antenna.

Additionally, the length and configuration of the wire can affect the axial stiffness and ease of puncture. With reference to <FIG>, a simplified diagram of a flexible antenna system <NUM>, according to some embodiments, is illustrated. The flexible antenna system <NUM> may be suitable for use in, for example, surgical, diagnostic, therapeutic, or biopsy procedures. While some embodiments are provided herein with respect to such procedures, any reference to medical or surgical instruments and medical or surgical methods is non-limiting. The systems, instruments, and methods described herein may be used for animals, human cadavers, animal cadavers, portions of human or animal anatomy, non-surgical diagnosis, as well as for industrial systems and general robotic or teleoperational systems.

As shown in <FIG>, the flexible antenna system <NUM> includes an antenna assembly <NUM> at a distal end of the antenna system <NUM> and a cable <NUM> (sometimes referred to as a conducting cable assembly) that extends between a proximal end of the antenna system <NUM> and the antenna assembly <NUM>. In some embodiments, the antenna assembly <NUM> is formed separately from the cable <NUM> and is coupled to a portion of the cable <NUM>. The cable <NUM> may assume a variety of configurations capable of conducting electricity/electrical signals. The antenna assembly <NUM> includes an antenna tip portion <NUM> coupled to a distal end of an antenna body <NUM>. An antenna base <NUM> of the antenna assembly <NUM> is coupled to or integrally formed with the cable <NUM>. The antenna body <NUM> may be formed with one or more of a variety of generally cylindrical or tubular patterns including bar and ring patterns, cutout patterns, slotted patterns, and helical patterns, as will be described in detail below. A sheath <NUM> surrounds the cable <NUM> and, in some embodiments, surrounds portions of the antenna assembly <NUM>. The sheath may be formed, for example, from a plastic material, elastomeric, or otherwise flexible material.

<FIG> illustrates the flexible antenna system <NUM> exploded along a longitudinal axis A. In some embodiments the cable <NUM> may be a coaxial cable including an inner conductor <NUM> surrounded by a dielectric insulator layer <NUM>. An outer conductor <NUM> surrounds the dielectric insulator layer <NUM>. A protective plastic jacket <NUM> surrounds the outer conductor <NUM>. The inner conductor <NUM>, the dielectric insulator <NUM>, the outer conductor <NUM>, and the jacket <NUM> may all be coaxial with the axis A. Other coaxial cable configurations with different configurations, shapes, etc. of inner conductor, dielectric, and outer conductor could also be used.

<FIG> illustrate various embodiments for coupling the cable <NUM> to the antenna assembly <NUM>. <FIG> illustrates an antenna assembly <NUM> according to some embodiments. The antenna assembly <NUM> may be substantially similar to the antenna assembly <NUM>, with differences as described. The antenna assembly <NUM> includes antenna body <NUM> coupled to or integrally formed with an antenna tip portion <NUM>. The antenna body <NUM> includes an antenna base <NUM> and antenna body distal end <NUM>. The antenna assembly <NUM> is coupled to a cable <NUM> which may be substantially similar to cable <NUM>. The cable <NUM> includes a jacket <NUM> and an outer conductor <NUM>. In the embodiment of <FIG>, the antenna assembly <NUM> is coupled to and in electrical connection with the cable <NUM> via outer conductor <NUM>. The coupling between the antenna body <NUM> and the outer conductor <NUM> may be achieved by crimping, welding, soldering, or other connections that produce electrical connection. Alternatively, the outer conductor <NUM> may be form fitted within the antenna base <NUM>, where the antenna base <NUM> is placed around a distal end of the outer conductor <NUM>. In another embodiment, the antenna body can be cut directly from the coaxial cable. In such embodiments, the inner conductor of the cable may be left unconnected to the antenna body <NUM> or could connect at the antenna tip portion <NUM>.

<FIG> illustrates an antenna assembly <NUM> according to some embodiments. The antenna assembly <NUM> may be substantially similar to the antenna assembly <NUM>, <NUM> with differences as described. The antenna assembly <NUM> includes the antenna body <NUM>, the antenna tip portion <NUM>, the antenna base <NUM> and antenna body distal end <NUM> as previously described. The antenna assembly <NUM> is coupled to a cable <NUM> which may be substantially similar to cable <NUM>, <NUM>. The cable <NUM> includes the jacket <NUM>, the outer conductor <NUM>, and an inner conductor <NUM>. In the embodiment of <FIG>, the distal section of the antenna assembly <NUM> is coupled to and in electrical connection with the cable <NUM> via inner conductor <NUM>. The coupling between the antenna body <NUM> and the inner conductor <NUM> may be achieved by crimping, welding, soldering, or other connections that produce electrical connection. The inner conductor <NUM> extends through a central lumen <NUM> of the antenna body <NUM> and connects to a distal end of the antenna assembly <NUM> such as at the antenna tip portion <NUM>. The inner conductor <NUM>, in this configuration, may provide axial strength to the antenna assembly <NUM>.

<FIG> illustrates an antenna assembly <NUM> and a cable <NUM> according to some embodiments. The antenna assembly <NUM> is substantially similar to the antenna assembly <NUM>, and the cable <NUM> is substantially similar to cable <NUM>. The cable <NUM> includes the jacket <NUM>, the outer conductor <NUM>, and an inner conductor <NUM>. In this embodiment, the inner conductor <NUM> may extend partially through the central lumen <NUM> of the antenna body <NUM> and may attach to an inner surface of the antenna body <NUM>. The coupling between the antenna body <NUM> and the inner conductor <NUM> may be achieved by crimping, welding, soldering, or other connections that produce electrical connection. In this embodiment the inner conductor <NUM> is connected to the antenna body <NUM> near the antenna base <NUM>. As shown in this embodiment, the inner conductor <NUM> may be bent at approximately <NUM> degrees to connect with the antenna assembly <NUM>. Alternatively, the inner conductor may be unbent. The inner conductor <NUM>, in this configuration, may provide axial strength to the antenna assembly <NUM> if it is connected towards the distal end of the antenna body. In other embodiments, the inner conductor <NUM> may connect anywhere along the length of the antenna body <NUM>. The outer conductor <NUM> may be left unconnected to the antenna assembly <NUM> or may be coupled to the antenna assembly <NUM> as described with respect to <FIG>. In the case where the outer conductor is not electrically connected to the antenna body, an insulating body may be needed to provide mechanical coupling but not electrical coupling.

<FIG> illustrates an antenna assembly <NUM> according to some embodiments. The antenna assembly <NUM> may be substantially similar to the antenna assembly <NUM> with any differences as described. In this embodiment, a coupling strut <NUM> extends proximally from the antenna base <NUM>. The antenna assembly <NUM> is coupled to the cable <NUM> which may be substantially similar to cable <NUM>. The cable <NUM> includes the jacket <NUM>, the outer conductor <NUM>, a dielectric insulator layer <NUM>, and an inner conductor <NUM>. In this embodiment, the coupling strut <NUM>, is electrically connected to the inner conductor <NUM> by a weld joint <NUM> (or, alternatively, solder, adhesive, or a combination of solder, adhesive, and/or weld such as laser weld). The weld joint <NUM> is illustrated as a butt joint, although other types of joints may be applicable.

<FIG> illustrates the antenna assembly <NUM> according to some embodiments. In this embodiment, the coupling strut <NUM> is coupled to the inner conductor <NUM> by sleeve <NUM>. The sleeve <NUM> may be electrically conductive (i.e., formed from an electrically conductive material) so that the inner conductor <NUM> is spaced apart from the coupling strut <NUM>. In some embodiments the inner conductor <NUM> and the antenna base <NUM> are in physical contact with each other and encased within the sleeve <NUM>. If the inner conductor <NUM> and the coupling strut <NUM> remaining in physical contact to each other, the sleeve <NUM> may be electrically non-conductive. Although the above <FIG> have illustrated the antenna base <NUM> connected to the inner conductor <NUM>, the same coupling mechanisms (e.g., a weld joint or a sleeve) may, alternatively, be applied to connect the antenna base <NUM> to the outer conductor <NUM> instead.

<FIG> illustrate various embodiments of antenna tip portions that may be used as the antenna tip portion <NUM>, <NUM>. In some embodiments, the antenna tip portion is formed from the same material as the antenna body <NUM>, <NUM>. In other embodiments, the antenna tip portion may be formed separately and attached to the antenna body <NUM>, <NUM>. <FIG> illustrates a side view of an antenna tip portion <NUM> according to some embodiments. The antenna tip portion <NUM> includes a base portion <NUM> and multiple tabs or tip sections <NUM>. The antenna tip portion <NUM> includes six tip sections <NUM>, but alternative embodiments may include more or fewer tip sections. In various embodiments, the antenna tip portion may be integral with the antenna body. For example, the antenna tip portion may be formed from a distal end section of the antenna body by cutting away areas of the antenna body to form the tip sections. <FIG> illustrates a side view of the antenna tip portion <NUM> with the tip sections <NUM> drawn together. The tip sections <NUM> may be crimped or collapsed so that the distal portion of each tip section <NUM> is substantially in contact with the distal portion of the other tip sections <NUM> to form a cone. In some embodiments, the tip sections <NUM> may be further held in the cone shape such as by an adhesive, a weld (e.g., laser weld), solder, or other mechanism to preserve the cone shape and configuration. The resulting antenna tip portion <NUM> may be used, for example, in puncturing or separating tissue. The antenna tip portion <NUM> may be used with any of the antenna bodies previously described. In various alternatives, the antenna tip portion may be blunt rather than pointed, with rounded or square tips for example, to traverse tissue when sent with a needle. The tip portion could also be made entirely out of the same material or out of two materials. In one example, the very distal tip is formed from stainless steel or another type of material that may be sharpened to enable easy puncture through tissue. The distal end of the tip may be made from plastic to isolate it from the antenna body. The different materials can be glued, over molded, welded, threaded and screwed, etc. or joined by any other means.

The use of tabbed sections for crimping may also or alternatively be applied at the antenna bases <NUM>, <NUM> or strut <NUM>. In these embodiments, the tabbed sections may be crimped until the tabbed sections engage in contact with a portion of the cable, such as the inner or outer conductor. For example in the embodiment of <FIG>, tabbed sections at the antenna proximal end <NUM> may be crimped against the outer conductor <NUM> to form an electrical connection between at least some of the crimped, tab sections and the conductor <NUM>. The coupling may further be secured in place by, for example, weld points, solder, adhesive, or another type of securing technique.

<FIG> illustrates a side cross-sectional view of an antenna tip portion <NUM> according to some embodiments. The antenna tip portion <NUM> includes a conical section <NUM> and an insert section <NUM>. The insert section <NUM> may be set within a distal end <NUM> of an antenna body (e.g., antenna body <NUM>, <NUM>). The insert section <NUM> engages with inner surfaces <NUM> of the receiving distal end <NUM>. According to some embodiments, the insert section <NUM> is secured to select portions of the inner surfaces of the receiving distal end <NUM> at weld points <NUM> (e.g., one or more weld points around a perimeter of the insert section <NUM>). The weld points <NUM> may alternatively be points of solder or adhesion using some other material/securing approach. In some embodiments, the antenna body may be sandwiched between an insert and a portion of the tip that goes concentrically around the outside diameter of the antenna body. Upon application of heat, these two sections will melt together to form a good bond. Holes in the antenna body may need to be formed in order to allow the material to flow through.

<FIG> illustrates a side cross-sectional view of an antenna tip portion <NUM> according to some embodiments. The antenna tip portion <NUM> includes the conical section <NUM> and a coupling section <NUM>. The coupling section <NUM> includes inner threads <NUM>, around an interior perimeter of the antenna tip portion <NUM>, secured to a threaded distal end <NUM> of an antenna body (e.g., antenna body <NUM>, <NUM>). The distal end <NUM> of the antenna body includes outer threads <NUM> around a perimeter of the distal end. The antenna tip portion <NUM> may be secured to the antenna body by threading the inner threads <NUM> onto the outer threads <NUM>. The threaded connection may provide a secure lock between the antenna tip portion and the antenna body. Additionally, the coupling may be further secured by welding, soldering, or cementing with adhesive/etc. The structure can be additionally heated to further melt the plastic and enhance the bond.

<FIG> illustrates an antenna tip portion <NUM> with a conical section <NUM> insertable into a receiving distal end <NUM> of an antenna body. The conical section <NUM> includes tabs <NUM> attached to an insert <NUM>. The insert <NUM> includes two distinct bars extending from a proximal end of the conical section <NUM> toward the receiving distal end <NUM> of the antenna body. Alternatively, the insert <NUM> may be a single block extending from the conical section <NUM> (e.g., a round "peg") that has one or more tabs <NUM> at various points around the insert <NUM>'s circumference (e.g., equidistant points, etc.).

The receiving distal end <NUM> of the antenna body includes one or more receiving slots <NUM> that have a shape corresponding to that of the tabs <NUM>. For example, if the tabs <NUM> are each round, the corresponding receiving slots <NUM> are round, with a radius just larger than that of a tab <NUM> to allow the tabs <NUM> to enter the receiving slots <NUM> and remain there. Although described as being round, the receiving slots <NUM> (and the corresponding tabs <NUM>) may assume a variety of shapes, so long as the shapes correspond to each other (e.g., round tabs to round slots, square tabs to square holes, etc.).

In use, the insert <NUM> is inserted into the receiving distal end <NUM> until the tabs <NUM> releasably engage with corresponding receiving slots <NUM>. This is facilitated by the insert <NUM> having a size (e.g., radius) that is just smaller than the radius of the corresponding receiving distal end <NUM>, such that the tabs <NUM>'s heights may cause them to "snap" into place once they reach corresponding receiving slots <NUM>. After releasably engaging with corresponding receiving slots <NUM>, they may be further secured into place by adhesive or some other mechanism like heating and melting plastic, or otherwise left secured merely by the friction force between tabs <NUM> and walls of corresponding receiving slots <NUM>.

<FIG> illustrate various embodiments of cylindrical patterned antenna bodies that may be used as the antenna body <NUM>, <NUM>. The antenna bodies are radiating structures that generate radiation patterns as shown, for example, in <FIG>. In the absence of shielding around the antenna body or other obstruction to the radiation pattern, the radiation pattern transverse to the longitudinal axis of the antenna may extend further than the radiation pattern distal of the antenna tip. The antenna bodies may be formed from steel or another suitable electrically conductive material or may be coated with a conductive material. <FIG> illustrates a double bar ring antenna body <NUM> according to some embodiments. The antenna body <NUM> is generally cylindrical and axially aligned along an axis A1. A central lumen <NUM> extends longitudinally through the antenna body <NUM>. The antenna body <NUM> may be fabricated by cutting portions from a tube to form longitudinal bars <NUM> and radial rings <NUM>. In this embodiment, the rings <NUM> are arranged about and along the axis A1. Each ring <NUM> is spaced apart from another ring <NUM> by a pair of bars <NUM> arranged in parallel on opposite sides of the axis A1. The paired bars <NUM> at a level L1 may be rotated approximately <NUM> degrees relative to the paired bars <NUM> at an adjacent level L2. A variety of configurations of the paired bar antenna body may be suitable. For example, the paired bars may have a length D1 that is longer, shorter, or the same as the height D2 of the ring. The antenna body may further include additional cut-outs, rounded corners, or variations between the structure at adjacent levels to achieve desired flexibility, antenna performance, or ease of manufacture.

<FIG> illustrates a single bar ring antenna body <NUM> according to some embodiments. The antenna body <NUM> is generally cylindrical and axially aligned along an axis A2. A central lumen <NUM> extends longitudinally through the antenna body <NUM>. The antenna body <NUM> may be fabricated by cutting slots into a tube to form longitudinal bars <NUM> and radial rings <NUM>. In this embodiment, the rings <NUM> are arranged about and along the axis A2. Each ring <NUM> is spaced apart from another ring <NUM> by a single bar <NUM>. The bar <NUM> at a level L1 may be rotated approximately <NUM> degrees relative to the bar <NUM> at an adjacent level L2. Each ring <NUM> defines a ring edge <NUM>, and each bar <NUM> defines a bar edge <NUM>. The angle of the intersecting edges <NUM>, <NUM> may be selected to reduce stress under bend conditions. For example, each angle may be approximately <NUM> degrees as shown in <FIG>. In other embodiments the angle may be larger or smaller or the angles may be different at different levels. In some embodiments, the edges <NUM>, <NUM> are rounded instead of square so as to further reduce stress under bend conditions, therefore added to the resiliency of the materials of the patterned cylindrical structure. Sections of the tubing also be thinned or shaped in certain ways to allow material spaces to move and enhance flexibility.

<FIG> illustrates a helical antenna body <NUM> according to some embodiments. The antenna body <NUM> is generally cylindrical and axially aligned along an axis A3. A central lumen <NUM> extends longitudinally through the antenna body <NUM>. The antenna body <NUM> may have end surfaces <NUM>, <NUM> be fabricated by cutting a helical slot <NUM> into a tube to form a helical coiled ribbon structure <NUM>. In some embodiments, the helical ribbon structure <NUM> is formed by laser cutting a tube. Alternatively, instead of being laser cut, the helical ribbon structure may be formed by injection molding.

<FIG> illustrates a slotted antenna body <NUM> according to some embodiments. The antenna body <NUM> is generally cylindrical and axially aligned along an axis A4. The antenna body <NUM> may include spiral slots <NUM> that extend less than <NUM> degrees around the body. In alternative embodiments, the antenna body may be formed from a tube with symmetrical or non-symmetrical cuts, including a non-symmetrical pattern of slots.

The ring bar structure may be advantageous over other structures because of the compromise between bending and axial stiffness. The bars allow good axial stiffness and the cutouts allow bending flexibility. In the case of the helix, because there is not a lot of axial support, this antenna may not be able to puncture tissues as easily. The single bar structure or any other slotted structure would have performances between the ring bar structure and helix. However, the helix shows better radiation profiles than the ring bar and the single ring bar configurations. The need for certain mechanical properties may need to be balanced with the radiation pattern outcomes.

The overall antenna assembly <NUM> of <FIG> may be designed materially and structurally to allow for greater flexibility than is available with rigid conducting materials used in traditional antennas that have a small form factor used to access various locations of target tissue. For example, the antenna assembly <NUM> may need to bend through <NUM> to <NUM> bends and as low as <NUM> with the ability to recover for insertion straight through a target tissue. In other words, the flexible plastic deformation limit of certain materials in a particular patterned cylinder, such as copper, is reached and the material plastically deforms when placed in tight bends through tissue, leaving the antenna assembly bent and unable to recover. This makes it hard to aim an antenna assembly towards target tissue.

Accordingly, the material used for the structure of the antenna assembly <NUM> and any antenna assembly or antenna body described herein may be selected to improve upon the plastic deformation limit and the ability of the antenna assembly to recover its form and re-straighten after passing through a particularly tight bend. This may be accomplished by the material selection for the antenna assembly <NUM>. In some embodiments, the antenna body may be constructed of a highly elastic first material that is plated with a conductive second material. The first material may be more elastic than the second material. The second material may be plated onto the first material on an external surface of the antenna body, i.e. a surface facing away from the longitudinal axis of the antenna assembly.

The first material may be selected from materials that have highly elastic properties relative to less elastic materials such as copper. For example, the first material may be a beryllium-copper alloy (BeCu), nickel titanium (NiTi), or some other similarly plastic material such as steel. Notably, first material does not need to be conductive for emitting radiation at any wavelengths. This is enabled by the plating of the second material onto the first material. The second material may be a conductive material to enable the operation of the antenna assembly as a radiating antenna for ablation of tissue. For example, the second material may be a silver plating or a gold plating onto the material selected as the first material. The relative thickness of the plating for the second material may depend on the frequency or frequencies of operation for the flexible antenna system <NUM>. In some examples, the frequency may be on the order of megahertz to gigahertz, for example approximately <NUM> to approximately <NUM>. For example, operation may be selected to be at approximately <NUM>. At such frequencies, the skin depth of the second material may be sufficiently small, such as on the order of microns, that the plating does not have to be very thick. Therefore, the flexibility of the antenna assembly <NUM> remains intact from the characteristics of the first material.

As a result of the material selection and selection of the appropriate structural patterning, the antenna assembly <NUM> and any antenna assembly or antenna body described herein maintains a flexible plastic deformation limit that exceeds the strain imposed on the materials of the antenna assembly while working through a tight bend in a lumen. The antenna assembly and particularly the antenna body <NUM> is therefore able to recover its original form/shape after exiting such a luminal bend, in contrast to existing copper or other materials that would remain deformed due to the lower plastic deformation limits of such materials. As noted above, the antenna tip (e.g., antenna tip portion <NUM>) may be formed from the same or different materials as the antenna body <NUM>.

The patterned structure formed in the tubular antenna body according to the different approaches described herein may also contribute to the flexibility of the antenna body. The resilience and flexibility of the antenna body is demonstrated, for example, in the illustration of FIG. 6A, which provides a simplified diagram of a flexible antenna system <NUM> (e.g. similar to system <NUM>) in a succession of unbent, bent and recovered states.

As illustrated, the antenna assembly <NUM> includes an antenna body <NUM> coupled to an antenna tip portion <NUM> and an antenna base <NUM> coupled to an outer conductor <NUM> with a jacket <NUM>. In <FIG>, the antenna assembly <NUM> begins in the unbent state with a straight configuration along a longitudinal axis A4 (e.g., its default configuration). The antenna assembly <NUM> may be inserted into anatomic passageways in a patient via a flexible and/or steerable elongate device, such as a flexible catheter, and navigated toward a region of interest within the patient anatomy.

In the example illustrated in <FIG>, as the antenna assembly <NUM> is navigated toward the region of interest, it may be subject to forces that place it in a bent state. As illustrated, the antenna assembly <NUM> is bent around a radius R <NUM> curve. The radius R <NUM> of the curve may be on the order of <NUM> to <NUM> or as small as <NUM>, and the antenna assembly <NUM> is able to bend around this radius R <NUM> because it is formed of the first material selected due to its relatively high elastic properties. The patterned structure of the antenna body may also contribute to the elasticity of the antenna assembly.

After the antenna assembly, and particularly the antenna body <NUM>, finished pushing through the bend of radius R <NUM>, the antenna assembly straightens out, recovering and restraightening back to approximately the antenna body's original shape. This recovered state allows the antenna assembly to approach the target tissue with a predicable trajectory. In some embodiments, the original body shape is a substantially straight shape. In other embodiments, the original body shape if a curved shape allowing for a curved insertion trajectory. This, again, is possible due to the material selected as the first material, and the antenna assembly is able to ablate tissue from energy emitted from the antenna body <NUM> due to the conductive second material plating the flexible first material. Once in the tissue, power is applied at a particular frequency in either CW or pulsed mode to perform the ablation.

In addition to the flexible aspects of the present disclosure, embodiments of the present disclosure also provide for controlling tissue ablation parameters by controlling one or more parameters of an antenna body. Different parameters affect the resonant frequency of the antenna including the length of the antenna body, number of repetitions within a pattern, angle of cuts in the pattern, materials, tubing diameter and wall thickness, etc. These parameters may be used to affect an ablation zone size created by the flexible antenna system in operation. For example, the length of the antenna body may be referred to as an active length and may include or be defined by a length of the patterned section of the patterned cylindrical structure of the antenna body (e.g., antenna body <NUM> or any of the alternatives described herein). The patterned section of the antenna body is where most of the energy dissipates for tissue ablation, although some energy will also be dissipated from the respective ends of the antenna structure. Therefore, altering the active length may alter the resonant frequency of the antenna assembly, altering the delivery of ablation energy, and thus altering the ablation zone size during treatment. As another example, the number of repetitions of the pattern for the patterned cylindrical structure describes the spacing between portions of the antenna body. This may be referred to generally as a pitch between the antenna body elements, namely the cutout space between the material of the antenna body (resulting in a total number of antenna body elements within the overall active length). Further, the wall thickness refers to a thickness of the first and second materials of the patterned cylindrical structure together as seen from a cross sectional end view.

For example, referring to the double bar ring embodiments as illustrated in <FIG>, as the length of a bar <NUM> increases (e.g., length D1 increases), a center frequency is reduced. Further, as the rings <NUM> get longer (i.e., length D2 increases) the center frequency is again reduced. The span of a bar <NUM> is the circumferential length of the bar. For example, a bar with a span of <NUM> degrees would span a quarter of the distance around the axis A1 if the bar is viewed in a cross section perpendicular to the axis A1. As the span of each bar is increased, the center frequency is reduced. Finally, decreasing the thickness of the walls of the antenna body decreases the center frequency. The converse would result in increasing the center frequency for each parameter. More generally, changing the different parameters of the antenna assembly may have a varying impact depending on the particular antenna structure, i.e. double bar ring, single bar ring, helical, etc..

Thus, according to embodiments of the present disclosure, the pitch, effective current path length, wall thickness, and cut pattern are different inter-related dimensions of the antenna body that provide extra degrees of freedom from which to control one or more parameters including resonant frequency, maximum allowable strain seen on the antenna assembly, and the ablation size. For example, in the case of the helical antenna body of <FIG>, an effective current path length <NUM> is determined directly by the chosen center frequency; usually it is chosen as a quarterwave length. A structure length SL will define the size of the ablation zone. In so far as they affect the effective current path length <NUM>, the pitch P and the cut pattern also affect the center frequency and should be chosen to produce the necessary current path length and the appropriate structure length. For instance, in a helical antenna of <FIG>, the pitch P, number of turns, and radius R of the turns can be used to adjust the maximum strain on the antenna when at a bend and also set so that the ablation zone is the desired size.

For example, the maximum strain on the antenna may be adjusted by increasing the diameter of the patterned cylindrical structure. There is often a practical limit to how much the diameter may be increased due to the size limitations of a delivery device working channel, e.g. a delivery device such as a flexible and/or steerable elongate device, such as a flexible catheter, inserted into anatomic passageways and navigated toward a region of interest within the patient anatomy. Alternatively, the maximum strain may be reduced by decreasing the pitch between turns of an antenna body. This impacts the ablation zone size as well, which may be mitigated by, for example, increasing the effective current path length by increments of λ/<NUM> while also adjusting the pitch.

Some exemplary effects of patterns and their parameters that may affect ablation zone size are illustrated in <FIG>. In <FIG>, a flexible antenna system <NUM> includes a cable <NUM>, an antenna body <NUM> (e.g., substantially similar to the antenna body <NUM> or any of the other antenna bodies described herein). An antenna base <NUM> of the antenna body <NUM> is coupled to the distal end <NUM> of the cable <NUM>. The illustration further shows the antenna tip portion <NUM>, and identifies the varying pitch <NUM> (referring generally to a spacing between elements of the antenna body <NUM>).

Several different radiation patterns <NUM>, <NUM>, and <NUM> are illustrated for purposes of discussion. Looking at a variety of different parameters relating to the antenna assembly, the current path length of the antenna body <NUM> has a relatively large influence on the resonant frequency and bandwidth for the antenna's radiation pattern compared to other parameters. in the case of the helical configuration, the current path length is the length of the unwrapped spiral and has the largest influence on the resonant frequency.

The structure length, i.e. the overall length of patterned portion of the antenna body <NUM>, (i.e. in the case of the helix, the helix length) has a relatively smaller influence on the resonant frequency as compared to the effective current path length. By adjusting the pitch of the repeated elements (i.e. the spirals), we can achieve different effective current path length of antenna with the same resonant frequency.

Generally, the longer the length of the antenna body <NUM>, the longer the ablation lesion length (e.g., in a length parallel to the axis along which the antenna assembly extends from proximal to distal end) in the target tissue, while the ablation lesion width (in a plane transverse to that running parallel to the antenna assembly) remains generally the same. Thus, by increasing the pitch <NUM>, the length of the ablation zone size changes. For example, at a given starting pitch <NUM>, the radiation pattern <NUM> results (and, therefore, ablation zone size corresponding to the radiation pattern <NUM>. By increasing the pitch <NUM> (making it larger), the radiation pattern changes to radiation pattern <NUM>, which is longer in the parallel axis and generally the same width in the transverse axis. In contrast, by decreasing the pitch <NUM> (making it smaller), the radiation pattern changes to radiation pattern <NUM> which is shorter in the parallel axis as compared to the radiation pattern <NUM> (but still generally the same width in the transverse axis).

With the configurations of the flexible antenna system discussed herein, embodiments of the present disclosure therefore provide the ability to tailor the ablation zone size in target tissue during ablation. This is in contrast to monopole antennas, where the length of the wire, and the corresponding ablation size in tissue, are both set by the operating frequency.

Several different examples are discussed in further detail below that provide for adjusting one or more parameters of the antennas in order to affect ablation zone size (i.e., tailor the size), maximum strain on the antenna, a combination of both, and/or other parameters.

<FIG> is a simplified diagram of a flexible and adjustable antenna system <NUM> according to some embodiments. The adjustable antenna system <NUM> illustrated in <FIG> includes many substantially similar elements to those discussed above with respect to the flexible antenna system <NUM> or other embodiments disclosed herein with the differences as explained. In <FIG> a cable <NUM> is a coaxial cable with a jacket <NUM>, outer conductor <NUM>, dielectric insulator <NUM>, and inner conductor <NUM>. The antenna system <NUM> includes an antenna base <NUM>, antenna body <NUM>, and antenna tip portion <NUM>.

A push/pull element <NUM> extends through the cable <NUM>, for example through a passage created in the dielectric insulator <NUM> that runs approximately parallel to the inner conductor <NUM> (but which is not in contact with the inner conductor <NUM>). The cable may be a hollow coaxial cable to accommodate the push/pull element <NUM>, or alternatively the push/pull element <NUM> may be located off-center from the inner conductor <NUM>.

In the illustrated embodiment, the antenna assembly comprising antenna body <NUM> and antenna tip portion <NUM> may be electrically (and mechanically) attached to either the inner conductor <NUM> or the outer conductor <NUM>, while the push/pull element <NUM> extends through the center of the antenna body <NUM> and connects with the antenna tip <NUM> at the distal end of the antenna assembly. This mechanical connection at the antenna tip <NUM> allows the push/pull element <NUM> to exert a push and/or pull force on the antenna tip <NUM>, for example provided by a user of the flexible antenna system according to embodiments of the present disclosure.

In some embodiments, the push/pull element <NUM> extends along the entire length of the cable and is mechanically controlled at the proximal end of the cable along with other aspects of the flexible and/or steerable elongate device (e.g., a manual control or a robotic control using a motor or other actuator). Thus, when a user pushes on the push/pull element <NUM> at the proximal end, e.g. by physically pushing or pulling on the proximal end of the push/pull element 806at a location outside of the proximal end of the cable, this is mechanically transferred along the length of the cable to a distal portion of the antenna assembly and the connection to the antenna tip <NUM>.

In an alternative embodiment, the push/pull element <NUM> does not extend along the entire length of the cable. Instead, a small motor or other actuator or electric interface may be placed at a location in or on the cable closer to the distal end of the antenna assembly, at which point the push/pull element <NUM> extends the rest of the way to the antenna tip <NUM>. For example, the small interface may be electrically coupled to a controller at the proximal end of the cable, and actuate in response to command signals sent from the controller to push the push/pull element <NUM> or pull it, depending on the command signals received. In other embodiments, the push/pull element <NUM> may be formed from a shape memory allow, such as nitinol, such that the shape may be altered when a current is applied (such as per a command signal from a controller).

By actuating the push/pull element <NUM>, the length of the antenna body <NUM> may be altered, either by elongating the antenna body <NUM> (when pushing the push/pull element <NUM> in the distal direction) or compressing the antenna body <NUM> (when pulling the push/pull element <NUM> in the proximal direction). This changes the pitch between turns of the antenna body <NUM> as well as the overall length of the patterned cylindrical structure. This, in turn, dynamically changes delivery of energy and accordingly changes ablation zone size. In the process of changing the pitch length, the center frequency of operation also changes. That change in the center frequency of operation may be addressed by shifting the operating frequency to reduce reflected power due to impedance mismatches.

<FIG> is a simplified diagram of a flexible and adjustable antenna system <NUM> according to some alternative embodiments. The adjustable antenna system illustrated in <FIG> includes many substantially similar elements to those discussed above with respect to the flexible antenna system generally. For example, in <FIG> the coaxial cable <NUM> is used. The antenna assembly system <NUM> includes the antenna base <NUM>,the antenna body <NUM>, and an antenna tip portion <NUM>.

This embodiment also includes an outer sheath <NUM>. The outer sheath <NUM> surrounds the rest of the cable as well as the antenna assembly, and is able to slide longitudinally relative to the cable (generally parallel to the axis of the cable) and the antenna assembly. As can be seen from <FIG>, the antenna assembly has a blunt antenna tip portion <NUM> (e.g., a square end, an elliptically shaped end, etc. with our without rounded edges), with a sufficient area to come in contact with a sheath tip <NUM> at the distal end of the assembly.

The outer sheath <NUM> may encapsulate the full length of the cable, and thus extend from the proximal end of the cable to the distal end where the antenna assembly is located along with other aspects of the flexible and/or steerable elongate device. The outer sheath <NUM> may be controllable to move in response to a push or pull action. The push or pull action may, in such embodiments, be applied at the proximal end and translated along the length of the cable until it is applied to the antenna tip portion <NUM> by the sheath tip <NUM>.

In some alternative embodiments, the outer sheath <NUM> does not extend the full length of the cable, but rather instead may be controlled by a small motor or other electric interface placed at a location on or in the cable closer to the distal end of the antenna assembly. For example, the small interface may be electrically coupled to a controller at the proximal end of the cable, and actuate in response to command signals sent from the controller to push the outer sheath <NUM> away from the antenna tip portion <NUM>, or pull the outer sheath <NUM> against the antenna tip portion <NUM>, depending on the command signals received.

In operation, pulling the outer sheath <NUM> towards the proximal direction causes the sheath tip <NUM> to press against some or most of the surface of the antenna tip portion <NUM>. This, in turn, applies a compressive force against the antenna tip portion <NUM> (e.g., since the movement of the outer sheath <NUM> does not occur with any corresponding movement of the cable within the outer sheath <NUM>), which decreases the pitch of the helical antenna body <NUM> and, therefore, the ablation zone size (e.g., a smaller length).

In another example, pushing the outer sheath <NUM> towards the distal direction away from the antenna tip portion <NUM> causes the sheath tip <NUM> to relax the force applied against the antenna tip portion <NUM>. In some embodiments, the sheath tip <NUM> and the antenna tip distal end <NUM> are not mechanically joined together, but rather are only in physical contact with each other depending on the amount of force applied by the sheath tip <NUM>. Thus, as the sheath tip <NUM> is extended distally, this reduced the amount of force applied by the sheath tip <NUM> against the antenna tip portion <NUM>, which may allow the antenna body <NUM> to expand, therefore increasing the pitch <NUM> between cutouts and correspondingly altering energy delivery to increase ablation size.

In some other embodiments, the sheath tip <NUM> and the antenna tip portion <NUM> are mechanically joined together, such as by adhesive. Thus, when the sheath tip <NUM> is extended distally, instead of just releasing some of the force previously applied against the antenna tip portion <NUM>, the movement of the sheath tip <NUM> exerts a force in the distal direction that pulls the antenna tip portion <NUM> towards the distal direction. This again increases the pitch <NUM> to change the pitch length, modify the center frequency of operation, and thus modifying the ablation zone size. That change in the center frequency of operation may be addressed by shifting the operating frequency should too much power be reflected at the interface between the conductor (inner or outer) electrically connected to the antenna assembly.

In some embodiments, movement of the outer sheath <NUM> may be tele-operationally controlled by coupling the sheath to an actuator located along the length of the antenna system or at a proximal end of the antenna system.

<FIG> illustrate simplified diagram of a flexible and adjustable antenna system <NUM> according to some embodiments. As illustrated in <FIG>, the antenna assembly <NUM> includes a distal end <NUM> and an antenna body <NUM> formed from two distinct portions, inner tube <NUM> and outer tube <NUM>. These tubes <NUM>, <NUM> are slidable with respect to each other as will be discussed in more detail below. Each of the inner and outer tubes <NUM>, <NUM> may be formed from a nonconductive, flexible, elastic material that has a plastic deformation limit greater than the amount of strain placed on the material when traversing, e.g., a <NUM> bend in a tortuous pathway. For example, one or both of the inner and outer tubes <NUM>, <NUM> may be formed from a material such as BeCu, NiTi, or steel as just a few examples. The inner tube <NUM> may include conductive traces along an outer surface of the inner tube <NUM>, while the outer tube <NUM> may include corresponding conductive traces along an inner surface of the outer tube <NUM>. Accordingly, electrical connections between the inner and outer tubes <NUM>, <NUM> may occur when the relative positioning of the inner tube to the outer tube aligns the conductive traces.

The conductive traces are illustrated as a first pattern 908a on the outer surface of the inner tube <NUM> - in particular, etched, engraved, printed on, adhered to, or otherwise secured to the outer surface of the inner tube <NUM>. The first pattern 908a is illustrated as being a spiral around the outer surface of the inner tube <NUM> extending from a first inner contact 906a at a distal end of the inner tube <NUM> to a second inner contact 906b at a proximal end of the inner tube <NUM>.

Likewise with respect to the outer tube <NUM>, conductive traces are etched/engraved/printed/adhered/etc. as a second pattern 908b on the inner surface of the outer tube <NUM>. The second pattern 908b is illustrated as being a spiral around the inner surface of the outer tube <NUM> extending from a first outer contact 910a at a distal end of the outer tube <NUM> to a second outer contact 910b at a proximal end of the outer tube <NUM>, where the flexible and adjustable antenna system <NUM> connects to the cable <NUM>.

According to some embodiments, either the first pattern 908a or the second pattern 908b is electrically connected by default to a conductor of the cable to receive electrical energy to generate radiation patterns (<FIG>) for tissue ablation. Thus, the connected pattern receives the electrical energy and generates the radiation pattern to cause the ablation zone size, as set by the pitch of the pattern. For example, if the second pattern 908b on the outer tube <NUM> is the one connected by default, then the radiation pattern is generated according to the parameters of the second pattern 908b.

As illustrated in <FIG>, the flexible and adjustable antenna system <NUM> is in a first configuration 900a according to some embodiments. The inner tube <NUM> is shown positioned within the hollow outer tube <NUM>, but in a configuration such that the first inner contact 906a is not in electrical contact with the first outer contact 910a, and likewise the second inner contact 906b and the second outer contact 910b. Thus, only the tube that is electrically connected by default to an energy source generates a radiation pattern, and therefore an ablation zone size, via the pattern. The default connection is with the second pattern 908b on the outer tube <NUM>. Thus, the radiation pattern generated is from the parameters, such as pitch, length, etc. of the second pattern 908b.

If it is desired to control/adjust the ablation zone size, then a user may adjust the flexible and adjustable antenna system <NUM> to a second configuration 900b, as illustrated in <FIG>. According to the example illustrated in <FIG>, the inner tube <NUM> has been rotated relative to the outer tube <NUM> so that the contacts are now over each other to some degree, providing an electrical connection between respective contacts on the inner and outer tubes <NUM>, <NUM>. In alternative embodiments, the relative position of the inner tube <NUM> to the outer tube <NUM> may be altered by altering a relative longitudinal position of the inner tube <NUM> to the outer tube <NUM> or a combination of altering the relative longitudinal position and relative rotational positions of inner tube <NUM> to outer tube <NUM>.

When adjusted to the second configuration 900b, the first inner contact 906a is now overlapping at least part of the first outer contact 910a, and the contacts are sufficiently close to each other so as to be in electrical and physical contact with the other. Likewise, the second inner contact 906b is now overlapping at least part of the second outer contact 910b, with the contacts sufficiently close to each other so as to be in electrical and physical contact with the other. Therefore, the first pattern 908a, which was not in electrical contact with the energy source previously as was the second pattern 908b's default connection, is now also in contact with that energy source.

As a result, the first pattern 908a is now conducting energy via the first and second inner contacts 906a, 906b being in connection with the corresponding first and second outer contacts 910a, 910b. Thus, electrical energy may now flow between the first and second inner contacts 906a, 906b via the first pattern 908a. As can be seen, since both the inner and outer patterns 908a, 908b are now conducting, both are contributing to the radiation pattern of the antenna assembly. This effectively reduces the pitch and increases the length of the radiating antenna, as both first and second patterns 908a, 908b contribute to the radiation pattern.

Although illustrated as just two patterns on the inner and outer tubes, embodiments of the present disclosure are also applicable to any number of different patterns and configurations, such that the tubes may move relative to each other to more than two different configurations to achieve more unique parameter combinations to change the radiation pattern contributing to the tissue ablation zone size.

The inner tube <NUM> is adjusted relative to the outer tube <NUM>, the outer tube <NUM> is adjusted relative to the inner tube <NUM>, or both tubes are adjusted relative to one another. The tubes may be manually adjusted from a proximal end or robotically actuated. For example, the tubes may have a set track on which they may twist between the first and second positions, with guides to indicate (e.g., via some form of tactile or electronic feedback) that the first or second positions have been reached.

The above examples, e.g. with respect to <FIG>, describe dynamic control/adjustment of the parameters contributing to the tissue ablation zone size for ablation. In other embodiments, this control/adjustment may be done statically, e.g. a set of antennas with varying parameters, e.g. antenna body length, pattern, pitch, radius, wire diameter, and material may be available and delivered for ablation depending on a desired ablation zone size.

<FIG> illustrates a method <NUM> for adjusting parameters for ablation size and location according to some embodiments. It is understood that additional processes can be provided before, during, and after the processes of method <NUM> and that some of the processes described can be replaced or eliminated from the method <NUM>. The method <NUM> may be manual or may be controlled by a processor of a control system (e.g., a control system <NUM>). At a process <NUM>, a desired ablation zone size and/or shape is determined, for example, by using external imaging techniques such as MRI, CT, ultrasound, or fluoroscopy; internal imaging techniques such as endobronchial ultrasonography (EBUS), intravascular ultrasonography (IVUS), optical coherence tomography (OCT); or a user input. At a process <NUM>, an adjustment of a configuration of the antenna system to treat tissue based on the desired ablation zone size and/or shape may be directed manually by a user or tele-operationally by the control system <NUM> of an adjustment mechanism. The configuration of the antenna system may be adjusted by adjusting one or more antenna parameters including antenna body length, pattern, pitch, radius, wire diameter, and material; and/or system parameters including cooling flow rate, ablation time, power, duty cycle, frequency, max temperature, and other energy characteristics; and/or position/orientation of the antenna. In some embodiments, the adjustment may be tele-operationally controlled by the control system <NUM>. In other embodiments, the control system <NUM> may provide instructions (e.g., via a display system or audio system) to instruct a user on making adjustments to the antenna system, including replacing antenna system components. At a process <NUM>, ablation energy is delivered to the tissue with the antenna system having the adjusted configuration. At a process <NUM>, an ablation zone size and/or shape, resulting from the delivered ablation energy, is evaluated. The evaluation may be conducted using external imaging techniques such as MRI, CT, ultrasound, or fluoroscopy; internal imaging techniques such as EBUS, IVUS, or OCT. Alternatively, the evaluation maybe conducted using measured impedance or other electrical properties of the tissue. At a process <NUM>, based on the evaluation a determination is made regarding whether further tissue ablation is needed. If further ablation is needed, processes <NUM>-<NUM> may be repeated with the antenna system repositioned or re-oriented, as needed. If no further ablation is needed, no further ablation energy may be provided at process <NUM>.

In some embodiments, an impedance mismatch and unwanted reflections at an interface between the cable and the antenna assembly may occur. To avoid these issues, a matching network may be applied. For example, a quarter wave transformer may be formed by changing the diameters of the inner conductor or dielectric. For instance, <NUM> Ohm cable could be used to impedance match. The quarter wave section may be formed by thinning the inner conductor <NUM> by ablation, necking, or joining another section of coaxial cable with a corresponding inner conductor <NUM> of a different size. Alternatively, the outer diameter of the cable may be increased or decreased to create the quarter wave transformer, though this also reaches size limitations due to the size limitations of the working channel.

In some embodiments, given possible challenges in thinning the inner conductor <NUM> to the appropriate diameter at the interface, the quarter wave transformer may be created by instead using a high dielectric constant material such as highly doped titanium dioxide (TiO2) in the polymer (e.g., polytetrafluoroethylene, or PTFE) of the sheath.

With respect to unwanted current propagation down the outside of the coax shaft, a choke or balun can be used to attenuate the electric field and not burn unnecessary tissue. Such chokes include bazooka baluns, or other sections of conductive tubing concentric to the outer conductor of the cable that are either floating or connected to the outer conductor in the proximal or distal ends. A double balun or choke can also be used; this structure is formed from two of the previously described structures for more current suppression. The dielectric between the choke/baluna nd the outer conductor can be plastics, water, ceramics, or any insulating material.

A second choice for attenuating unwanted currents is to utilize a highly resistive surface coating on the surface of the outer conductor. This can be painted, deposited, or otherwise applied to various sections of the outer conductor. Additionally, materials of lower conductivity could be spliced in the right places to the outer conductor to achieve a similar effect, such as graphene or aquadag for example.

Turning now to <FIG>, a method diagram 1000a is illustrated for designing a flexible helical antenna system according to some embodiments. In particular, the method 1000a illustrates aspects of configuring (e.g., including optimizing) the flexible antenna system <NUM> according to embodiments of the present disclosure. The discussion is also applicable to the various antenna body configurations. It is understood that additional steps can be provided before, during, and after the steps of method 1000a, and that some of the steps described can be replaced or eliminated from the method 1000a.

At block 1002a, the ablation zone size is identified or chosen that is desired for tissue ablation. With the ablation zone size identified/chosen, the structure length that creates radiation patterns to achieve just under the identified ablation zone size is selected.

At block 1004a, a working frequency is selected, which informs what the appropriate current path length. In the example of a helix, this corresponds to the unwrapped length of the helix. The length will be, for example, some multiple of a quarter or half wavelength depending on whether operation is at the first resonant frequency or the second resonant frequency (either of which is allowed according to embodiments of the present disclosure).

At block 1006a, the diameter of the antenna body <NUM> (e.g., <FIG>) is fixed based on the determined mechanical size of the working channel through which the antenna body <NUM> will traverse in use. For example, the working channel may be through a flexible and/or steerable elongate device, such as a flexible catheter, inserted into anatomic passageways and navigated toward a region of interest within the patient anatomy.

At block 1008a, the other parameters of the device and the pitch and number of repetitions is selected to correspond to the selected ablation length. For example, in the case of the helix, there will be confirmation that the windings for the selected helix length would not be too short for convenient regular operation as an antenna for tissue ablation).

At decision block 1010a, if the pitch is available and meets the necessary mechanical strain requirements, then the method 1000a proceeds to block 1014a.

At block 1014a, the pitch is set to the value determined at block 1008a and all parameters are fixed.

Returning to decision block 1010a, if the pitch is not available (e.g., too short for practical purposes), then the method 1000a instead proceeds to block 1012a. At block 1012a, the length used at block 1004a is changed to a multiple of the wavelength of the working frequency selected previously at block 1004a.

From there, the method 1000a returns to block 1006a and proceeds again as laid out above. Accordingly, the antenna may be optimized according to embodiments of the present disclosure, including by selection of the flexible material for the coil substrate (plated over with a conductive material), and including adjustability of the parameters of the flexible antenna system <NUM> to achieve different radiation patterns (<FIG>).

<FIG> illustrates a method diagram 1000b for designing a flexible antenna system. Method 1000b may be similar to method 1000a but is used for designing a different patterned antenna body, such as a ring and bar antenna body. In particular, the method 1000b illustrates aspects of configuring (e.g., including optimizing) the flexible antenna system <NUM> according to embodiments of the present disclosure. The discussion is also applicable to the various antenna body configurations. It is understood that additional steps can be provided before, during, and after the steps of method 1000b, and that some of the steps described can be replaced or eliminated from the method 1000b.

At block 1002b, the ablation zone size is identified or chosen that is desired for tissue ablation. With the ablation zone size identified/chosen, the structure length that creates radiation patterns to achieve just under the identified ablation zone size is selected.

At block 1004b, a working frequency is selected, which informs what the appropriate current path length.

At block 1006b, the maximum diameter of the antenna body is fixed based on the determined mechanical size of the working channel through which the antenna body will traverse in use. For example, the working channel may be through a flexible and/or steerable elongate device, such as a flexible catheter, inserted into anatomic passageways and navigated toward a region of interest within the patient anatomy.

At block 1008b, a ring height, radius, bar height, and bar width, and tube thickness are chosen to meet resonance at the working frequency.

At decision block 1010b, if the ring and bar dimensions are available and meet the necessary mechanical strain requirements, then the method 1000b proceeds to block 1014b. For example, if the strain remains lower than the plastic deformation, the method <NUM> proceeds to block 1014b; otherwise the parameters of the antenna are tweaked and the process is repeated.

At block 1014b, the dimensions are set to the value determined at block 1008b and all parameters are fixed.

Returning to decision block 1010b, if the dimensions are not available, then the method 1000b instead returns to block 1010b.

Accordingly, the antenna may be optimized according to embodiments of the present disclosure, including by selection of the flexible material for the substrate (plated over with a conductive material), and including adjustability of the parameters of the flexible antenna system <NUM> to achieve different radiation patterns (<FIG>).

Turning now to <FIG>, a method diagram is illustrated for configuring a flexible antenna system according to some embodiments. In particular, the method <NUM> illustrates aspects of manufacturing (e.g., assembling) the flexible antenna system <NUM> according to embodiments of the present disclosure. The discussion is applicable to the various antenna body configurations. It is understood that additional steps can be provided before, during, and after the steps of method <NUM>, and that some of the steps described can be replaced or eliminated from the method <NUM>.

At block <NUM>, a pattern is cut, such as laser cut, into a hollow cylinder. This creates a patterned cylindrical structure, such as the ones introduced above. The hollow cylinder may be composed of a material that has a relatively low conductive property, for example a beryllium-copper alloy (BeCu), nickel titanium (NiTi), or some other similarly plastic material such as steel.

At block <NUM>, the patterned cylindrical structure is plated with a conductive material to enable the operation of the antenna assembly <NUM> as a radiating antenna for ablation of tissue. The plating may be, for example, a silver plating or a gold plating. The relative thickness of the plating may depend on the frequency or frequencies of operation for the flexible antenna system <NUM>. Although discussed as occurring after the pattern is cut, in some embodiments the cylinder is plated and then the pattern is cut.

At block <NUM>, a tip is shaped (optional) for the distal end of the patterned cylindrical structure. For example, the tip may be formed from the material at the end of the patterned cylindrical structure, such as by cutting the end of the open tube into multiple tip sections that are then crimped (e.g., bent at their interface with the remaining material of the flexible antenna system <NUM> such as that of the antenna body <NUM>), so that the distal portion of each tip section is substantially in contact with the distal portion of the other tip sections to form a cone as the antenna tip, such as discussed with respect to <FIG>. Alternatively, the tip may be a separate component welded to the distal end of the patterned cylindrical structure (<FIG>), held in place by tabs (<FIG>) or screwed into each other (<FIG>). These are just some examples. Block <NUM> may be an optional one in method <NUM>.

At block <NUM>, the proximal end of the patterned cylindrical structure, which since it is plated may also be referred to as the antenna assembly <NUM> according to the embodiments introduced with <FIG> herein, is coupled to the distal end of the cable. As part of that coupling, the base of the antenna may be electrically coupled to either the inner or the outer conductor of the cable (in examples where the cable <NUM> is a coaxial cable). In some embodiments, only one of the conductors is coupled to the antenna; in other embodiments, one of the conductors is coupled to the proximal end of the antenna while the other conductor (e.g., the inner) is coupled to the distal end as well.

In some embodiments, block <NUM> then occurs (i.e., this is an optional part of method <NUM>). At block <NUM>, an adjustment device is coupled to the patterned cylindrical structure (which is used in operation to change the ablation size of the device by adjusting pitch and/or other parameters of the antenna). This is illustrated as optional in <FIG> to recognize that some devices may include this element while others might not. The adjustment device may assume a variety of forms/approaches, such as the examples illustrated in <FIG>. As a result of the above manufacturing method, a flexible antenna system is provided as discussed with respect to embodiments of the present disclosure. The blocks <NUM>, <NUM>, and <NUM> and the processes described therein may occur in different sequences.

<FIG> illustrates a method <NUM> for antenna component selection according to some embodiments. It is understood that additional processes can be provided before, during, and after the processes of method <NUM> and that some of the processes described can be replaced or eliminated from the method <NUM>. The method <NUM> may be controlled by a processor of a control system (e.g., a control system <NUM>).

At a process <NUM>, a desired ablation zone size and/or shape is determined, for example, by using external imaging techniques such as MRI, CT, ultrasound, or fluoroscopy; internal imaging techniques such as endobronchial ultrasonography (EBUS), intravascular ultrasonography (IVUS), optical coherence tomography (OCT); or a user input. This process may include receiving information about a location of lesion, such as by user input or by imaging technology. Additionally or alternatively, this process may include receiving information about surrounding anatomical structures such as blood vessels, by user input or by imaging technology. At a process <NUM>, information about a type of tissue to be ablated is received. The tissue type may include, for example, lung, stomach, intestine, liver, kidney, kidney stone, bladder, prostate, uterus, ovary, or other types of anatomical tissue. Tissue type may be provided as an input by a user (e.g. by inputting a target organ or intended medical procedure) or automatically identified using imaging techniques (e.g. automatic identification of organs within scans from MRI, CT, ultrasound, fluoroscopy, OCT, etc.).

At a process <NUM>, information about a type of delivery device (e.g. a flexible elongate delivery device) may be received by the control system for use in determining a size (e.g. a maximum size) of a customizable component of an antenna system to be delivered within a working channel of the delivery device. In one embodiment, the delivery device information can determined by the control system based the determination of tissue type (e.g. organ and passageway access to the organ) to be ablated. For example, the control system may identify a maximum size of a delivery device based on a type of target organ (e.g. lung, liver, kidney, etc.) to be accessed and size of passageways (e.g. airways, rectum, esophagus, etc.) providing access to the target organ. The control system may then determine the maximum size of an antenna system that can be received within the working channel of the delivery device. At a process <NUM>, a determination may be made regarding the selection of an antenna component from a plurality of available antenna components. The determination may be made by the control system (e.g., control system <NUM>). The antenna components may include, for example a plurality of antenna bodies <NUM> that vary based on physical parameters, for example, helical pitch, wire length, and pattern (e.g., bar height, bar width, ring height, and cut-out pattern). In some embodiments, a visual or audible indicator may provide a user with instructions for selecting the determined antenna component. In some embodiments, as with a robotic system, the antenna component may be automatically chosen. At a process <NUM>, a determination is made regarding treatment parameters such as ablation power, time, and/or frequency needed to generate the desired ablation zone size and/or shape with the selected antenna component. The determination may be made by the control system (e.g., control system <NUM>) and may be based on any of the received or determined information including the tissue type and the selected antenna component. At a process <NUM>, optionally, a size of a predicted or actual ablation zone may be stored. This process may be performed after a delivery of ablation energy to the anatomical tissue. The stored ablation zone may be used to guide a secondary ablation.

In alternative embodiments, after delivering power using the selected antenna, the ablation may be evaluated and the processes <NUM>, <NUM>, <NUM> may be repeated and further ablation may be conducted at the target anatomical site.

The flexible antenna system according to embodiments of the present disclosure (including flexible and adjustable antenna systems) may be operated in any number of ways, including manually as well as in automated fashion, to ablate target tissue (e.g., using microwave ablation as just one RF example to which these embodiments apply). For automated approaches, robotic systems may be employed for precision targeting of tissue and surgical operation.

To that end, this disclosure describes various instruments and portions of instruments in terms of their state in three-dimensional space. As used herein, the term "position" refers to the location of an object or a portion of an object in a three-dimensional space (e.g., three degrees of translational freedom along Cartesian x-, y-, and z-coordinates). As used herein, the term "orientation" refers to the rotational placement of an object or a portion of an object (three degrees of rotational freedom - e.g., roll, pitch, and yaw). As used herein, the term "pose" refers to the position of an object or a portion of an object in at least one degree of translational freedom and to the orientation of that object or portion of the object in at least one degree of rotational freedom (up to six total degrees of freedom). As used herein, the term "shape" refers to a set of poses, positions, or orientations measured along an object.

<FIG> is a simplified diagram of a teleoperated medical system <NUM> according to some embodiments. In some embodiments, teleoperated medical system <NUM> may be suitable for use in, for example, surgical, diagnostic, therapeutic, or biopsy procedures, including tissue ablation (such as tumor tissue ablation). While some embodiments are provided herein with respect to such procedures, any reference to medical or surgical instruments and medical or surgical methods is non-limiting. The systems, instruments, and methods described herein may be used for animals, human cadavers, animal cadavers, portions of human or animal anatomy, non-surgical diagnosis, as well as for industrial systems and general robotic or teleoperational systems.

As shown in <FIG>, medical system <NUM> generally includes a manipulator assembly <NUM> for operating a medical instrument <NUM> in performing various procedures on a patient P (e.g., tissue ablation with a flexible antenna system <NUM> according to embodiments of the present disclosure). The manipulator assembly <NUM> may be teleoperated, non-teleoperated, or a hybrid teleoperated and non-teleoperated assembly with select degrees of freedom of motion that may be motorized and/or teleoperated and select degrees of freedom of motion that may be non-motorized and/or non-teleoperated. Manipulator assembly <NUM> is mounted to or near an operating table T. A master assembly <NUM> allows an operator (e.g., a surgeon, a clinician, or a physician as illustrated in <FIG>) to view the interventional site and to control manipulator assembly <NUM>.

Master assembly <NUM> may be located at an operator console which is usually located in the same room as operating table T, such as at the side of a surgical table on which patient P is located. However, it should be understood that operator O can be located in a different room or a completely different building from patient P. Master assembly <NUM> generally includes one or more control devices for controlling manipulator assembly <NUM>. The control devices may include any number of a variety of input devices, such as joysticks, trackballs, data gloves, trigger-guns, hand-operated controllers, voice recognition devices, body motion or presence sensors, and/or the like. To provide operator O a strong sense of directly controlling instruments <NUM> the control devices may be provided with the same degrees of freedom as the associated medical instrument <NUM>. In this manner, the control devices provide operator O with telepresence or the perception that the control devices are integral with medical instruments <NUM>.

In some embodiments, the control devices may have more or fewer degrees of freedom than the associated medical instrument <NUM> and still provide operator O with telepresence. In some embodiments, the control devices may optionally be manual input devices which move with six degrees of freedom, and which may also include an actuatable handle for actuating instruments (for example, for closing grasping jaws, applying an electrical potential to an electrode and/or antenna, delivering a medicinal treatment, and/or the like).

Manipulator assembly <NUM> supports medical instrument <NUM> and may include a kinematic structure of one or more non-servo controlled links (e.g., one or more links that may be manually positioned and locked in place, generally referred to as a set-up structure), and/or one or more servo controlled links (e.g. one more links that may be controlled in response to commands from the control system), and a manipulator. Manipulator assembly <NUM> may optionally include a plurality of actuators or motors that drive inputs on medical instrument <NUM> in response to commands from the control system (e.g., a control system <NUM>). The actuators may optionally include drive systems that when coupled to medical instrument <NUM> may advance medical instrument <NUM> into a naturally or surgically created anatomic orifice. Other drive systems may move the distal end of medical instrument <NUM> in multiple degrees of freedom, which may include three degrees of linear motion (e.g., linear motion along the X, Y, Z Cartesian axes) and in three degrees of rotational motion (e.g., rotation about the X, Y, Z Cartesian axes). Additionally, the actuators can be used to actuate an articulable end effector of medical instrument <NUM> for grasping tissue in the jaws of a biopsy device and/or the like. Actuator position sensors such as resolvers, encoders, potentiometers, and other mechanisms may provide sensor data to medical system <NUM> describing the rotation and orientation of the motor shafts. This position sensor data may be used to determine motion of the objects manipulated by the actuators.

Teleoperated medical system <NUM> may include a sensor system <NUM> with one or more sub-systems for receiving information about the instruments of manipulator assembly <NUM>. Such sub-systems may include a position/location sensor system (e.g., an electromagnetic (EM) sensor system); a shape sensor system for determining the position, orientation, speed, velocity, pose, and/or shape of a distal end and/or of one or more segments along a flexible body that may make up medical instrument <NUM>; and/or a visualization system for capturing images from the distal end of medical instrument <NUM>.

Teleoperated medical system <NUM> also includes a display system <NUM> for displaying an image or representation of the surgical site and medical instrument <NUM> generated by sub-systems of sensor system <NUM>. Display system <NUM> and master assembly <NUM> may be oriented so operator O can control medical instrument <NUM> (e.g., including tissue ablation via RF, such as microwave frequencies) and master assembly <NUM> with the perception of telepresence.

In some embodiments, medical instrument <NUM> may have a visualization system (discussed in more detail below), which may include a viewing scope assembly that records a concurrent or real-time image of a surgical site and provides the image to the operator or operator O through one or more displays of medical system <NUM>, such as one or more displays of display system <NUM>. The concurrent image may be, for example, a two or three dimensional image captured by an endoscope positioned within the surgical site. In some embodiments, the visualization system includes endoscopic components that may be integrally or removably coupled to medical instrument <NUM>. However in some embodiments, a separate endoscope, attached to a separate manipulator assembly may be used with medical instrument <NUM> to image the surgical site. The visualization system may be implemented as hardware, firmware, software or a combination thereof which interact with or are otherwise executed by one or more computer processors, which may include the processors of a control system <NUM>.

Display system <NUM> may also display an image of the surgical site and medical instruments captured by the visualization system. In some examples, teleoperated medical system <NUM> may configure medical instrument <NUM> and controls of master assembly <NUM> such that the relative positions of the medical instruments are similar to the relative positions of the eyes and hands of operator O. In this manner operator O can manipulate medical instrument <NUM> and the hand control as if viewing the workspace in substantially true presence. By true presence, it is meant that the presentation of an image is a true perspective image simulating the viewpoint of a physician that is physically manipulating medical instrument <NUM>.

In some examples, display system <NUM> may present images of a surgical site recorded pre-operatively or intra-operatively using image data from imaging technology such as, computed tomography (CT), magnetic resonance imaging (MRI), fluoroscopy, thermography, ultrasound, optical coherence tomography (OCT), thermal imaging, impedance imaging, laser imaging, nanotube X-ray imaging, and/or the like. The pre-operative or intra-operative image data may be presented as two-dimensional, three-dimensional, or four-dimensional (including e.g., time based or velocity based information) images and/or as images from models created from the pre-operative or intra-operative image data sets.

In some embodiments, often for purposes of imaged guided surgical procedures, display system <NUM> may display a virtual navigational image in which the actual location of medical instrument <NUM> is registered (i.e., dynamically referenced) with the preoperative or concurrent images/model. This may be done to present the operator O with a virtual image of the internal surgical site from a viewpoint of medical instrument <NUM>. In some examples, the viewpoint may be from a tip of medical instrument <NUM>. An image of the tip of medical instrument <NUM> and/or other graphical or alphanumeric indicators may be superimposed on the virtual image to assist operator O controlling medical instrument <NUM>. In some examples, medical instrument <NUM> may not be visible in the virtual image.

In some embodiments, display system <NUM> may display a virtual navigational image in which the actual location of medical instrument <NUM> is registered with preoperative or concurrent images to present the operator O with a virtual image of medical instrument <NUM> within the surgical site from an external viewpoint. An image of a portion of medical instrument <NUM> or other graphical or alphanumeric indicators may be superimposed on the virtual image to assist operator O in the control of medical instrument <NUM>. As described herein, visual representations of data points may be rendered to display system <NUM>. For example, measured data points, moved data points, registered data points, and other data points described herein may be displayed on display system <NUM> in a visual representation. The data points may be visually represented in a user interface by a plurality of points or dots on display system <NUM> or as a rendered model, such as a mesh or wire model created based on the set of data points. In some examples, the data points may be color coded according to the data they represent. In some embodiments, a visual representation may be refreshed in display system <NUM> after each processing operation has been implemented to alter data points.

Teleoperated medical system <NUM> also includes control system <NUM>. Control system <NUM> may include at least one memory and at least one computer processor (not shown) for effecting control between medical instrument <NUM>, master assembly <NUM>, sensor system <NUM>, and display system <NUM>. Control system <NUM> also includes programmed instructions (e.g., a non-transitory machine-readable medium storing the instructions) to implement some or all of the methods described in accordance with aspects disclosed herein, including instructions for providing information to display system <NUM>. While control system <NUM> is shown as a single block in the simplified schematic of <FIG>, the system may include two or more data processing circuits with one portion of the processing optionally being performed on or adjacent to manipulator assembly <NUM>, another portion of the processing being performed at master assembly <NUM>, and/or the like. The processors of control system <NUM> may execute instructions comprising instruction corresponding to processes disclosed herein, such as controlling the dynamically adjusting antenna parameters according embodiments discussed above. Any of a wide variety of centralized or distributed data processing architectures may be employed. Similarly, the programmed instructions may be implemented as a number of separate programs or subroutines, or they may be integrated into a number of other aspects of the teleoperational systems described herein. In one embodiment, control system <NUM> supports wireless communication protocols such as Bluetooth, IrDA, HomeRF, IEEE <NUM>, DECT, and Wireless Telemetry.

In some embodiments, control system <NUM> may receive force and/or torque feedback from medical instrument <NUM>. Responsive to the feedback, control system <NUM> may transmit signals to master assembly <NUM>. In some examples, control system <NUM> may transmit signals instructing one or more actuators of manipulator assembly <NUM> to move medical instrument <NUM>. Medical instrument <NUM> may extend into an internal surgical site within the body of patient P via openings in the body of patient P. Any suitable conventional and/or specialized actuators may be used. In some examples, the one or more actuators may be separate from, or integrated with, manipulator assembly <NUM>. In some embodiments, the one or more actuators and manipulator assembly <NUM> are provided as part of a teleoperational cart positioned adjacent to patient P and operating table T.

Control system <NUM> may optionally further include a virtual visualization system to provide navigation assistance to operator O when controlling medical instrument <NUM> during an image-guided surgical procedure. Virtual navigation using the virtual visualization system may be based upon reference to an acquired preoperative or intraoperative dataset of anatomic passageways. The virtual visualization system processes images of the surgical site imaged using imaging technology such as computerized tomography (CT), magnetic resonance imaging (MRI), fluoroscopy, thermography, ultrasound, optical coherence tomography (OCT), thermal imaging, impedance imaging, laser imaging, nanotube X-ray imaging, and/or the like. Software, which may be used in combination with manual inputs, is used to convert the recorded images into segmented two dimensional or three dimensional composite representation of a partial or an entire anatomic organ or anatomic region. An image data set is associated with the composite representation. The composite representation and the image data set describe the various locations and shapes of the passageways and their connectivity. The images used to generate the composite representation may be recorded preoperatively or intra-operatively during a clinical procedure. In some embodiments, a virtual visualization system may use standard representations (i.e., not patient specific) or hybrids of a standard representation and patient specific data. The composite representation and any virtual images generated by the composite representation may represent the static posture of a deformable anatomic region during one or more phases of motion (e.g., during an inspiration/ expiration cycle of a lung).

During a virtual navigation procedure, sensor system <NUM> may be used to compute an approximate location of medical instrument <NUM> with respect to the anatomy of patient P. The location can be used to produce both macro-level (external) tracking images of the anatomy of patient P and virtual internal images of the anatomy of patient P. The system may implement one or more electromagnetic (EM) sensor, fiber optic sensors, and/or other sensors to register and display a medical implement together with preoperatively recorded surgical images, such as those from a virtual visualization system, are known. For example <CIT>) (disclosing "Medical System Providing Dynamic Registration of a Model of an Anatomic Structure for Image-Guided Surgery"), discloses one such system. Teleoperated medical system <NUM> may further include optional operations and support systems (not shown) such as illumination systems, steering control systems, irrigation systems, and/or suction systems. In some embodiments, teleoperated medical system <NUM> may include more than one manipulator assembly and/or more than one master assembly. The exact number of teleoperational manipulator assemblies will depend on the surgical procedure and the space constraints within the operating room, among other factors. Master assembly <NUM> may be collocated or they may be positioned in separate locations. Multiple master assemblies allow more than one operator to control one or more teleoperational manipulator assemblies in various combinations.

<FIG> is a simplified diagram of a medical instrument system <NUM> according to some embodiments. In some embodiments, medical instrument system <NUM> may be used as medical instrument <NUM> in an image-guided medical procedure performed with teleoperated medical system <NUM>. In some examples, medical instrument system <NUM> may be used for non-teleoperational exploratory procedures or in procedures involving traditional manually operated medical instruments, such as endoscopy as well as RF tissue ablation. Optionally medical instrument system <NUM> may be used to gather (i.e., measure) a set of data points corresponding to locations within anatomic passageways of a patient, such as patient P.

Medical instrument system <NUM> includes elongate device <NUM>, such as a flexible catheter, coupled to a drive unit <NUM>. Elongate device <NUM> includes a flexible body <NUM> having proximal end <NUM> and distal end or tip portion <NUM>. In some embodiments, flexible body <NUM> has an approximately <NUM> outer diameter. Other flexible body outer diameters may be larger or smaller.

Medical instrument system <NUM> further includes a tracking system <NUM> for determining the position, orientation, speed, velocity, pose, and/or shape of distal end <NUM> and/or of one or more segments <NUM> along flexible body <NUM> using one or more sensors and/or imaging devices as described in further detail below. The entire length of flexible body <NUM>, between distal end <NUM> and proximal end <NUM>, may be effectively divided into segments <NUM>. Tracking system <NUM> may optionally be implemented as hardware, firmware, software or a combination thereof which interact with or are otherwise executed by one or more computer processors, which may include the processors of control system <NUM> in <FIG>.

Tracking system <NUM> may optionally track distal end <NUM> and/or one or more of the segments <NUM> using a shape sensor <NUM>. Shape sensor <NUM> may optionally include an optical fiber aligned with flexible body <NUM> (e.g., provided within an interior channel (not shown) or mounted externally). In one embodiment, the optical fiber has a diameter of approximately <NUM>. In other embodiments, the dimensions may be larger or smaller. The optical fiber of shape sensor <NUM> forms a fiber optic bend sensor for determining the shape of flexible body <NUM>. In one alternative, optical fibers including Fiber Bragg Gratings (FBGs) are used to provide strain measurements in structures in one or more dimensions. Various systems and methods for monitoring the shape and relative position of an optical fiber in three dimensions are described in <CIT>) (disclosing "Fiber optic position and shape sensing device and method relating thereto"); <CIT>) (disclosing "Fiber-optic shape and relative position sensing"); and <CIT>) (disclosing "Optical Fibre Bend Sensor"). Sensors in some embodiments may employ other suitable strain sensing techniques, such as Rayleigh scattering, Raman scattering, Brillouin scattering, and Fluorescence scattering. In some embodiments, the shape of the elongate device may be determined using other techniques. For example, a history of the distal end pose of flexible body <NUM> can be used to reconstruct the shape of flexible body <NUM> over the interval of time. In some embodiments, tracking system <NUM> may optionally and/or additionally track distal end <NUM> using a position sensor system <NUM>. Position sensor system <NUM> may be a component of an EM sensor system with position sensor system <NUM> including one or more conductive coils that may be subjected to an externally generated electromagnetic field. Each coil of the EM sensor system then produces an induced electrical signal having characteristics that depend on the position and orientation of the coil relative to the externally generated electromagnetic field. In some embodiments, position sensor system <NUM> may be configured and positioned to measure six degrees of freedom, e.g., three position coordinates X, Y, Z and three orientation angles indicating pitch, yaw, and roll of a base point or five degrees of freedom, e.g., three position coordinates X, Y, Z and two orientation angles indicating pitch and yaw of a base point. Further description of a position sensor system is provided in <CIT>) (disclosing "Six-Degree of Freedom Tracking System Having a Passive Transponder on the Object Being Tracked").

In some embodiments, tracking system <NUM> may alternately and/or additionally rely on historical pose, position, or orientation data stored for a known point of an instrument system along a cycle of alternating motion, such as breathing. This stored data may be used to develop shape information about flexible body <NUM>. In some examples, a series of positional sensors (not shown), such as electromagnetic (EM) sensors similar to the sensors in position sensor <NUM> may be positioned along flexible body <NUM> and then used for shape sensing, in some embodiments with sufficient distance from the medical instrument <NUM> (e.g., a flexible antenna system <NUM> according to embodiments). In some examples, a history of data from one or more of these sensors taken during a procedure may be used to represent the shape of elongate device <NUM>, particularly if an anatomic passageway is generally static.

Flexible body <NUM> includes a channel <NUM> sized and shaped to receive a medical instrument <NUM>. <FIG> is a simplified diagram of flexible body <NUM> with medical instrument <NUM>, such as an ablation tool (such as microwave ablation) extended according to some embodiments. In some embodiments, medical instrument <NUM> may be used for procedures such as surgery, biopsy, ablation, illumination, irrigation, or suction. Medical instrument <NUM> can be deployed through channel <NUM> of flexible body <NUM> and used at a target location within the anatomy. Medical instrument <NUM> may include, for example, image capture probes, biopsy instruments, laser ablation fibers, and/or other surgical, diagnostic, or therapeutic tools. Medical tools may include, in addition to ablation antennae such as the flexible antenna system <NUM>, end effectors having a single working member such as a scalpel, a blunt blade, an optical fiber, an electrode, and/or the like. Medical instrument <NUM> may also be used with an image capture probe also within flexible body <NUM>. In various embodiments, medical instrument <NUM> may be an image capture probe that includes a distal portion with a stereoscopic or monoscopic camera at or near distal end <NUM> of flexible body <NUM> for capturing images (including video images) that are processed by a visualization system <NUM> for display and/or provided to tracking system <NUM> to support tracking of distal end <NUM> and/or one or more of the segments <NUM>. The image capture probe may include a cable coupled to the camera for transmitting the captured image data. In some examples, the image capture instrument may be a fiber-optic bundle, such as a fiberscope, that couples to visualization system <NUM>. The image capture instrument may be single or multispectral, for example capturing image data in one or more of the visible, infrared, and/or ultraviolet spectrums. Alternatively, medical instrument <NUM> may itself be the image capture probe. Medical instrument <NUM> may be advanced from the opening of channel <NUM> to perform the procedure and then retracted back into the channel when the procedure is complete. Medical instrument <NUM> may be removed from proximal end <NUM> of flexible body <NUM> or from another optional instrument port (not shown) along flexible body <NUM>.

Medical instrument <NUM> may additionally house cables, linkages, or other actuation controls (not shown) that extend between its proximal and distal ends to controllably bend the distal end of medical instrument <NUM>. Steerable instruments are described in detail in <CIT>) (disclosing "Articulated Surgical Instrument for Performing Minimally Invasive Surgery with Enhanced Dexterity and Sensitivity") and <CIT>) (disclosing "Passive Preload and Capstan Drive for Surgical Instruments").

Flexible body <NUM> may also house cables, linkages, or other steering controls (not shown) that extend between drive unit <NUM> and distal end <NUM> to controllably bend distal end <NUM> as shown, for example, by broken dashed line depictions <NUM> of distal end <NUM>. In some examples, at least four cables are used to provide independent "up-down" steering to control a pitch of distal end <NUM> and "left-right" steering to control a yaw of distal end <NUM>. Steerable elongate devices are described in detail in <CIT>) (disclosing "Catheter with Removable Vision Probe"). In embodiments in which medical instrument system <NUM> is actuated by a teleoperational assembly, drive unit <NUM> may include drive inputs that removably couple to and receive power from drive elements, such as actuators, of the teleoperational assembly. In some embodiments, medical instrument system <NUM> may include gripping features, manual actuators, or other components for manually controlling the motion of medical instrument system <NUM>. Elongate device <NUM> may be steerable or, alternatively, the system may be non-steerable with no integrated mechanism for operator control of the bending of distal end <NUM>. In some examples, one or more lumens, through which medical instruments can be deployed and used at a target surgical location, are defined in the walls of flexible body <NUM>.

In some embodiments, medical instrument system <NUM> may include a flexible bronchial instrument, such as a bronchoscope or bronchial catheter, for use in examination, diagnosis, biopsy, or treatment of a lung. Medical instrument system <NUM> is also suited for navigation and treatment of other tissues, via natural or surgically created connected passageways, in any of a variety of anatomic systems, including the colon, the intestines, the kidneys and kidney calices, the brain, the heart, the circulatory system including vasculature, and/or the like. Medical instrument system <NUM> may provide a working lumen to delivery tools such as diagnostic devices and/or or treatment tools including biopsy needles, ablation tools including antenna systems such as flexible antenna system <NUM>, and/or the like. Alternatively, medical instrument system <NUM> may include integrated biopsy and/or treatment tools including an integrated antenna system such as flexible antenna system <NUM>.

The information from tracking system <NUM> may be sent to a navigation system <NUM> where it is combined with information from visualization system <NUM> and/or the preoperatively obtained models to provide the physician or other operator with real-time position information. In some examples, the real-time position information may be displayed on display system <NUM> of <FIG> for use in the control of medical instrument system <NUM>. In some examples, control system <NUM> of <FIG> may utilize the position information as feedback for positioning medical instrument system <NUM>. Various systems for using fiber optic sensors to register and display a surgical instrument with surgical images are provided in <CIT>, disclosing, "Medical System Providing Dynamic Registration of a Model of an Anatomic Structure for Image-Guided Surgery,".

In some examples, medical instrument system <NUM> may be teleoperated within medical system <NUM> of <FIG>. In some embodiments, manipulator assembly <NUM> of <FIG> may be replaced by direct operator control. In some examples, the direct operator control may include various handles and operator interfaces for hand-held operation of the instrument.

<FIG> are simplified diagrams of side views of a patient coordinate space including a medical instrument mounted on an insertion assembly according to some embodiments. As shown in <FIG>, a surgical environment <NUM> includes a patient P is positioned on the table T of <FIG>. Patient P may be stationary within the surgical environment in the sense that gross patient movement is limited by sedation, restraint, and/or other means. Cyclic anatomic motion including respiration and cardiac motion of patient P may continue, unless patient is asked to hold his or her breath to temporarily suspend respiratory motion. Accordingly, in some embodiments, data may be gathered at a specific phase in respiration, and tagged and identified with that phase. In some embodiments, the phase during which data is collected may be inferred from physiological information collected from patient P. Within surgical environment <NUM>, a point gathering instrument <NUM> is coupled to an instrument carriage <NUM>. In some embodiments, point gathering instrument <NUM> may use EM sensors, shape-sensors, and/or other sensor modalities. Instrument carriage <NUM> is mounted to an insertion stage <NUM> fixed within surgical environment <NUM>. Alternatively, insertion stage <NUM> may be movable but have a known location (e.g., via a tracking sensor or other tracking device) within surgical environment <NUM>. Instrument carriage <NUM> may be a component of a manipulator assembly (e.g., manipulator assembly <NUM>) that couples to point gathering instrument <NUM> to control insertion motion (i.e., motion along the A axis) and, optionally, motion of a distal end <NUM> of an elongate device <NUM> in multiple directions including yaw, pitch, and roll. Instrument carriage <NUM> or insertion stage <NUM> may include actuators, such as servomotors, (not shown) that control motion of instrument carriage <NUM> along insertion stage <NUM>.

Elongate device <NUM> is coupled to an instrument body <NUM>. Instrument body <NUM> is coupled and fixed relative to instrument carriage <NUM>. In some embodiments, an optical fiber shape sensor <NUM> is fixed at a proximal point <NUM> on instrument body <NUM>. In some embodiments, proximal point <NUM> of optical fiber shape sensor <NUM> may be movable along with instrument body <NUM> but the location of proximal point <NUM> may be known (e.g., via a tracking sensor or other tracking device). Shape sensor <NUM> measures a shape from proximal point <NUM> to another point such as distal end <NUM> of elongate device <NUM>. Point gathering instrument <NUM> may be substantially similar to medical instrument system <NUM>.

A position measuring device <NUM> provides information about the position of instrument body <NUM> as it moves on insertion stage <NUM> along an insertion axis A. Position measuring device <NUM> may include resolvers, encoders, potentiometers, and/or other sensors that determine the rotation and/or orientation of the actuators controlling the motion of instrument carriage <NUM> and consequently the motion of instrument body <NUM>. In some embodiments, insertion stage <NUM> is linear. In some embodiments, insertion stage <NUM> may be curved or have a combination of curved and linear sections.

<FIG> shows instrument body <NUM> and instrument carriage <NUM> in a retracted position along insertion stage <NUM>. In this retracted position, proximal point <NUM> is at a position L<NUM> on axis A. In this position along insertion stage <NUM> an A component of the location of proximal point <NUM> may be set to a zero and/or another reference value to provide a base reference to describe the position of instrument carriage <NUM>, and thus proximal point <NUM>, on insertion stage <NUM>. With this retracted position of instrument body <NUM> and instrument carriage <NUM>, distal end <NUM> of elongate device <NUM> may be positioned just inside an entry orifice of patient P. Also in this position, position measuring device <NUM> may be set to a zero and/or another reference value (e.g., I=<NUM>). In <FIG>, instrument body <NUM> and instrument carriage <NUM> have advanced along the linear track of insertion stage <NUM> and distal end <NUM> of elongate device <NUM> has advanced into patient P. In this advanced position, the proximal point <NUM> is at a position L<NUM> on the axis A. In some examples, encoder and/or other position data from one or more actuators controlling movement of instrument carriage <NUM> along insertion stage <NUM> and/or one or more position sensors associated with instrument carriage <NUM> and/or insertion stage <NUM> is used to determine the position Lx of proximal point <NUM> relative to position L<NUM>. In some examples, position Lx may further be used as an indicator of the distance or insertion depth to which distal end <NUM> of elongate device <NUM> is inserted into the passageways of the anatomy of patient P.

Claim 1:
A system comprising:
a flexible instrument (<NUM>), comprising:
an antenna (<NUM>) having a distal tip portion (<NUM>), a proximal base (<NUM>), and an antenna body (<NUM>) therebetween,
wherein the antenna body comprises a patterned cylindrical structure having antenna body elements that are spatially separated from each other, the antenna body having a proximal end coupled to the proximal base and a distal end coupled to the distal tip portion; and
an adjustment device (<NUM>) coupled to the patterned cylindrical structure and configured to adjust pitch lengths between adjacent antenna body elements,
wherein the flexible instrument is configured to generate a radiation pattern (<NUM>, <NUM>, <NUM>) from the antenna that varies based on the pitch lengths between the adjacent antenna body elements to ablate tissue; and
a control system (<NUM>) configured to shift an operating frequency of power applied to the antenna to adjust for a change of a center frequency of operation of the antenna caused by adjusting the pitch lengths between the adjacent antenna body elements.