Abstract:
A foldable biplane G-arm for use with x-ray imaging and fluoroscopic imaging. The system includes a gantry that supports imaging machinery to allow two bi-planar imaging beams to be taken simultaneously or without movement of the equipment and/or patient. Additionally, the system provides a G-arm gantry with a folding arm configuration that can solve prominent problems with traditional C-arm and G-arm gantries. In particular, the folding arm enables the G-arm of the present invention to reduce or eliminate obstacles between surgeons and nurses and more easily adapt for insertion of surgical tables into the system for imaging procedures by pivoting out and away from a center focus point of the support gantry to provide improved access for moving patient tables into and out of position for imaging the patient.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority to, and the benefit of, co-pending U.S. Provisional Application No. 62/392,321, filed May 27, 2016, for all subject matter common to both applications. The disclosure of said provisional application is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a medical instrument suitable for use with bi-plane imaging (e.g., X-ray). In particular, the present invention relates to a mobile biplane G-arm configured with a folding arm enabling flexibly in the setup and operation of the G-arm in imaging applications. 
       BACKGROUND 
       [0003]    Generally, it is desirable to take X-rays of a patient from a number of different positions, preferably without the need for frequent repositioning of the patient. It is preferable that the X-ray apparatus not unduly encumber the space surrounding the patient to enable a physician to treat or otherwise attend to the patient without the need to repeatedly remove and replace the X-ray apparatus. 
         [0004]    C-arm X-ray equipment has been developed to meet these needs and has become well known in the medical arts of surgical and other interventional procedures. An example of conventional C-arm equipment is shown in  FIG. 1 . A description of the C-arm equipment depicted in  FIG. 1  is provided in U.S. Pat. No. 8,992,082, which is incorporated herein by reference. Generally, C-arm X-ray equipment is smart and flexible in operation, and in its positioning process, which can be deduced from the degrees of freedom of movement inherent in such a structure. Additionally, the C-arm gantry is typically mounted so as to enable rotational movement of the arm in two degrees of freedom. For example, a conventional C-arm gantry can be slidably mounted to the support structure to enable orbiting rotational movement of the C-arm about its center of curvature, represented in  FIG. 1  as direction A. The C-arm equipment can also provide lateral rotation which is a motion rotating along the horizontal axis, represented in  FIG. 1  as direction B. In addition, the C-arm equipment can also have an up-down motion along the vertical axis, represented in  FIG. 1  as direction C, a cross-arm motion along the horizontal axis, represented in  FIG. 1  as direction D, and a wig-wag motion along the vertical axis, represented in  FIG. 1  as direction E. 
         [0005]    However, this (technology, device, system, methodology, etc.) experiences some shortcomings. In particular, although the C-arm X-ray equipment is smart and flexible in its positioning capabilities, it is often desirable to take X-rays of a patient from multiple positions (e.g., bi-planar imaging), which can be difficult in such conventional setups. For example, when taking images from both the anteroposterior (AP) &amp; lateral (LT) positions (two perpendicular angles), the operators have to reposition the C-arm because C-arm configurations do not allow for such perpendicular bi-planar imaging. In particular, C-arm systems are configured to capture a single plane image at a time, such that to get images from two different planes, the C-arm must capture an image in one plane, then be repositioned to capture an image in another plane. 
         [0006]    In view of the shortcomings related to capturing bi-planar images with a traditional C-arm device, it is common for practitioners to utilize G-arm or G-shape arm equipment for taking images from different angles at the same time, without repositioning the imaging apparatus. In operation, when utilizing a G-arm or G-shaped arm, the two imaging beams (e.g., X-Rays) emitted from the two imaging sources (e.g., X-ray tubes) may cross at an iso-center. However, operation of the G-arm has its own shortcomings. Specifically, the bi-planar design of conventional G-arm equipment unduly encumbers a space surrounding the patient due to the 270 degree of mechanical angle of gantry coverage. This configuration creates obstacle between surgeon and nurses. Additionally, the G-arm can only adapt to a few surgical tables by slipping the gantry from their front, as reflected in the table positioning depicted in  FIG. 1 . 
       SUMMARY 
       [0007]    There is a need for a piece of equipment to enable bi-planar imaging without the shortcomings of traditional C-arm and G-arm configurations. The present invention is directed toward further solutions to address this need, in addition to having other desirable characteristics. Specifically, the present invention provides a mobile imaging apparatus that enables the advantages of both C-shaped, G-shaped, and ring-shaped arm configurations, without the shortcomings. The device of the present invention includes a gantry that supports imaging machinery (e.g., imaging energy emitters, imaging receptor, processing units, etc.). The gantry is formed to allow two bi-planar imaging beams to be taken simultaneously or without movement of the equipment and/or patient. Additionally, the present invention provides a G-arm gantry with a folding arm configuration can solve prominent problems with traditional C-arm and G-arm gantries. In particular, the folding arm enables to the G-arm of the present invention to reduce or eliminate obstacles between surgeons and nurses, more easily adapt for insertion of surgical tables, etc. 
         [0008]    In accordance with example embodiments of the present invention, a foldable G-arm bi-planar imaging apparatus is provided. The apparatus includes a support gantry having a generally arc shape about an interior center focus point with a first terminal end and a second terminal end, the first terminal end being at a distal end of a folding arm coupled in an articulating manner with the support gantry at a pivot point. The apparatus also includes a first imaging assembly positioned on the support gantry, the first imaging assembly comprising a first imaging energy emitter positioned opposite a first imaging receptor, wherein one of the first imaging energy emitter and the first imaging receptor is positioned at the first terminal end of the support gantry on the folding arm. The apparatus further includes a second imaging assembly positioned on the support gantry, the second imaging assembly includes a second imaging energy emitter positioned opposite a second imaging receptor, wherein one of the second imaging energy emitter or the second imaging receptor is positioned at the second terminal end of the support gantry. The apparatus also includes a control unit that moves and positions the support gantry. The action of the folding arm articulating about the pivot point results in whichever of the first imaging energy emitter or the first imaging receptor that is positioned at the first terminal end of the support gantry on the folding arm articulating in a first direction out and away from, or in a second direction in and toward, the center focus point of the generally arc shape support gantry, commensurate with an articulating direction of the folding arm about the pivot point. 
         [0009]    In accordance with aspects of the present invention, the first imaging assembly is positioned and oriented to emit imaging energy in an LT plane and the second imaging assembly is positioned and oriented to emit imaging energy in an AP plane, perpendicular to the LT plane. The first imaging assembly can be positioned and oriented to emit imaging energy in an AP plane and the second imaging assembly is positioned and oriented to emit imaging energy in an LT plane, perpendicular to the AP plane. 
         [0010]    In accordance with aspects of the present invention, the action of the folding arm articulating about the pivot point in the direction out and away from the center focus point of the generally arc shape of the support gantry achieves a sufficiently low position to coincide with a height of a surgical table, wherein the first terminal end of the support gantry is foldable to enable rotation of the first terminal end low enough to adapt to a height of a surgical table. A pivot angle of the folding arm can ranges between an angle of 0 degrees to 180 degrees. 
         [0011]    In accordance with aspects of the present invention, the first imaging receptor and the second imaging receptor are one of an image intensifier or a flat panel detector. The first imaging energy emitter and the second imaging energy emitter can be X-ray sources configured to produce X-ray beams. 
         [0012]    In accordance with example embodiments of the present invention, a foldable G-arm bi-planar imaging system is provided. The system includes a support gantry having a generally arc shape about an interior center focus point with a first terminal end and a second terminal end, the first terminal end being at a distal end of a folding arm coupled in an articulating manner with the support gantry at a pivot point. The system also includes a first imaging assembly positioned on the support gantry, the first imaging assembly including a first imaging energy emitter positioned opposite a first imaging receptor, wherein one of the first imaging energy emitter and the first imaging receptor is positioned at the first terminal end of the support gantry on the folding arm. The system further includes a second imaging assembly positioned on the support gantry, the second imaging assembly including a second imaging energy emitter positioned opposite a second imaging receptor, wherein one of the second imaging energy emitter or the second imaging receptor is positioned at the second terminal end of the support gantry. The system The system includes a control unit that moves and positions the support gantry and a processing and display device in communication with the first imaging assembly and the second imaging assembly, the processing and display device configured to receive raw image data and display an image on a display device. The action of the folding arm articulating about the pivot point results in whichever of the first imaging energy emitter or the first imaging receptor that is positioned at the first terminal end of the support gantry on the folding arm articulating in a first direction out and away from, or in a second direction in and toward, the center focus point of the generally arc shape support gantry, commensurate with an articulating direction of the folding arm about the pivot point. 
         [0013]    In accordance with aspects of the present invention, the first imaging assembly is positioned and oriented to emit imaging energy in an LT plane and the second imaging assembly is positioned and oriented to emit imaging energy in an AP plane, perpendicular to the LT plane. The first imaging assembly is positioned and oriented to emit imaging energy in an AP plane and the second imaging assembly can be positioned and oriented to emit imaging energy in an LT plane, perpendicular to the AP plane. 
         [0014]    In accordance with aspects of the present invention, the action of the folding arm articulating about the pivot point in the direction out and away from the center focus point of the generally arc shape of the support gantry achieves a sufficiently low position to coincide with a height of a surgical table, wherein the first terminal end of the support gantry is foldable to enable rotation of the first terminal end low enough to adapt to a height of a surgical table. A pivot angle of the folding arm can range between an angle of 0 degrees to 180 degrees. 
         [0015]    In accordance with aspects of the present invention, the first imaging receptor and the second imaging receptor are one of an image intensifier or a flat panel detector. The first imaging energy emitter and the second imaging energy emitter can be X-ray sources configured to produce X-ray beams. 
         [0016]    In accordance with example embodiments of the present invention, a method for utilizing a foldable G-arm bi-planar imaging apparatus is provided. The method includes positioning, via a control unit, a support gantry. The apparatus includes a support gantry having a generally arc shape about an interior center focus point with a first terminal end and a second terminal end, the first terminal end being at a distal end of a folding arm coupled in an articulating manner with the support gantry at a pivot point. The apparatus also includes a first imaging assembly positioned on the support gantry, the first imaging assembly having a first imaging energy emitter positioned opposite a first imaging receptor, wherein one of the first imaging energy emitter and the first imaging receptor is positioned at the first terminal end of the support gantry on the folding arm. The apparatus further includes a second imaging assembly positioned on the support gantry, the second imaging assembly having a second imaging energy emitter positioned opposite a second imaging receptor, wherein one of the second imaging energy emitter or the second imaging receptor is positioned at the second terminal end of the support gantry. The method also includes disengaging a locking mechanism securing the folding arm. The method further includes articulating the folding arm about the pivot point such that whichever of the first imaging energy emitter or the first imaging receptor that is positioned at the first terminal end of the support gantry on the folding arm is articulated in a first direction out and away from, or in a second direction in and toward, the center focus point of the generally arc shape support gantry, commensurate with an articulating direction of the folding arm about the pivot point. 
         [0017]    In accordance with aspects of the present invention, the articulation of the folding arm ranges between an angle of 0 degrees to 180 degrees. The articulation of the folding arm about the pivot point in the direction out and away from the center focus point of the generally arc shape of the support gantry can achieve a sufficiently low position to coincide with a height of a surgical table, such that the first terminal end of the support gantry is foldable to enable rotation of the first terminal end low enough to adapt to a height of a surgical table. 
         [0018]    In accordance with aspects of the present invention, the method can include articulating the folding arm in the second direction in and toward the center focus point of the generally arc shape support gantry and engaging the locking mechanism securing the folding arm in preparation for operation of the apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0019]    These and other characteristics of the present invention will be more fully understood by reference to the following detailed description in conjunction with the attached drawings, in which: 
           [0020]      FIG. 1  is an illustration of an example structure for a conventional C-arm as known in the art; and 
           [0021]      FIGS. 2A, 2B, and 2C  are diagrammatic illustrations of a G-arm apparatus, in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    An illustrative embodiment of the present invention relates to a G-arm imaging device with a folding arm configured to rotate a portion of the G-arm gantry down and away from the center of the G-arm gantry, enabling better access. In particular, the present invention relates to a G-arm imaging device with a folding arm located between the six o&#39;clock and the nine o&#39;clock position of the G-arm gantry. The folding arm is configured to fold/rotate an end portion of the gantry, enabling improved access and imaging functionality. The folding arm is configured such that the energy emitter or imaging receptor attached to the gantry at the nine o&#39;clock position is rotatable down and away from the central point of the gantry about the axis of the folding arm. 
         [0023]    The G-arm gantry configured with the folding arm of the present invention enables a user of the G-arm apparatus to have more flexibility and comfort when operating the G-arm. In particular, the folding arm enables a user to have more flexibility when moving the G-arm gantry by reducing obstacles and obstructions caused by convention G-arm constructions. Additionally, the folding arm provides users with the flexibility with respect positioning a surgical table in and around the G-arm gantry. For example, the folding arm can be articulated down and away from the center point of the G-arm gantry to enable surgical tables of varied sizes to be utilized with the G-arm apparatus. Similarly, the folding arm can also provide a user (e.g., a surgeon) with more measurable surgical space if needed. 
         [0024]      FIGS. 1 through 2C , wherein like parts are designated by like reference numerals throughout, illustrate an example embodiment or embodiments of an imaging device with a G-arm configuration and including a folding arm portion, according to the present invention. Although the present invention will be described with reference to the example embodiment or embodiments illustrated in the figures, it should be understood that many alternative forms can embody the present invention. One of skill in the art will additionally appreciate different ways to alter the parameters of the embodiment(s) disclosed, such as the size, shape, or type of elements or materials, in a manner still in keeping with the spirit and scope of the present invention. 
         [0025]    As utilized herein, the phrase “LT plane” refers to the mean or sagittal plane of a patient, and the phrase “AP plane” refers to the transverse or axial plane of a patient, which is perpendicular to the LT plane. Such terminology is utilized in compliance with conventional meanings in the field of medical imaging. 
         [0026]    Imaging systems are commonly utilized in the medical field and come in a variety of configurations for a variety of applications (e.g., C-arm single plane imager, G-arm bi-plane imager, etc.). An example of an imaging system configured for capturing bi-planar medical images (e.g., X-rays) of a patient is depicted in  FIG. 1 . In particular,  FIG. 1  depicts a conventional G-arm medical imaging system  100  and the main components that make up the G-arm medical imaging system  100 . The main components of the G-arm medical imaging system  100  system include a movable stand  102 , a imaging energy emitter  104  (e.g., an X-ray source, X-ray tube, etc.) and imaging receptor  106  (e.g., an image intensifier, flat panel detector, etc.) configured for a frontal view (or anteroposterior view), an imaging energy emitter  108  and imaging receptor  110  configured for a lateral view, and a patient table  112  configured to hold a patient between the imaging energy emitters  104 ,  108  and the imaging receptor  106 ,  110 . As would be appreciated by one skilled in the art, the imaging energy emitters  104 ,  108  can include any kind of suitable imaging energy emitters utilized for imaging a patient. For example, the imaging energy emitters  104 ,  108  can be electromagnetic radiation or x-imaging energy emitters configured to produce X-rays. The combination of elements in the G-arm medical imaging system  100  includes a gantry  114  that supports all of the components/machinery. The gantry  114  of the G-arm medical imaging system  100  is formed to allow two bi-planar images to be captured simultaneously or without movement of the equipment and/or the patient. In some instances, the gantry  114  is adjustable to change angles of the imaging machinery (e.g., the imaging energy emitters  104 ,  108  and imaging receptor  106 ,  110 ). Additionally, in some implementations, the imaging receptor  106 ,  110  portion of the G-arm medical imaging system  100  can be positioned on retractable and extendable arms, allowing the apparatus to have a larger access opening when not in operation, but to still provide bi-planar imaging capability during operation of the G-arm medical imaging system  100 . However, even with such retractable and extendable arms, the conventional G-arm system still requires patient tables  112  to enter the imaging area by longitudinally positioning the patient table  112  end-first along an axis normal to the center-point of the circular cross-sectional area having a perimeter of the G-arm gantry  114 , making access limited. More specifically, conventional G-arm systems are only configured to adapt to a surgical table with one end suspended; whereas the G-arm medical imaging system  100  of the present invention enables a patient table  112  to pass laterally over the G-arm gantry  114  (said differently, the G-arm gantry  114  can be pass through the patient table  112 , underneath the horizontal surface upon which the patient rests), without requiring positioning the patient table  112  longitudinally through the normal axis to the center-point of the circular cross-sectional area. 
         [0027]      FIGS. 2A-2C  depict example illustrations of an imaging apparatus  200  for use in accordance with the present invention. In particular,  FIGS. 2A-2C  depict different orientations of a G-arm bi-planar imaging apparatus  200  including a folding arm  202 . More specifically,  FIG. 2A  depicts the apparatus  200  with the folding arm  202  in an unfolded position,  FIG. 2B  depicts the apparatus  200  with the folding arm  202  in a partially folded position (e.g., between the unfolded position of  FIG. 2A  and the folded position in  FIG. 2C ), and  FIG. 2C  depicts the apparatus  200  with the folding arm  202  in a fully folded position. With respect to the particular type of operation for each of the configurations depicted in  FIGS. 2A-2C ,  FIG. 2A  depicts the apparatus  200  with the folding arm  202  in an imaging operational position (e.g., the positioning for operation of the apparatus  200  for performing imaging functions),  FIG. 2B  depicts the apparatus  200  with the folding arm transitioning between the operational position in  FIG. 2A  and a loading position in  FIG. 2C , and  FIG. 2C  depicts the apparatus  200  with the folding arm  202  folded down to a loading position (e.g., enabling a user to position a patent table  112  about a center focus point  206  of the apparatus  200 ). 
         [0028]      FIGS. 2A-2C  each depict the same apparatus  200  with the same components arranged in varied orientations for different modes of operation provided by the folding arm  202 . Accordingly, the components of the apparatus  200  are discussed with respect to each of the  FIGS. 2A-2C , unless otherwise specified. In accordance with an example embodiment of the present invention, the apparatus  200  includes a support gantry  204  having a generally arc shape, about an interior center focus point  206 , with a first terminal end  204   a  and a second terminal end  204   b , the first terminal end  204   a  being at a distal end of the folding arm  202 . The folding arm  202  is coupled in an articulating manner with the support gantry  204  at a pivot point  202   a . In accordance with an example embodiment of the present invention, the folding arm  202  is motorized to rotate from an operational state (as depicted in  FIG. 2A ) to an accessible state (as depicted in  FIG. 2C ). As would be appreciated by one skilled in the art, the folding arm  202  can be implemented utilizing any mechanism to enable the end portion of the gantry to rotate as depicted in  FIGS. 2A-2C . For example, the folding arm  202  can be implemented using a motorized pivotal axis implementing a flexible wiring connection to enable the foldable range of motion discussed herein. 
         [0029]    The apparatus  200  also includes a first imaging assembly positioned on the support gantry  204 , the first imaging assembly includes a first imaging energy emitter  208  positioned opposite a first imaging receptor  210 . In accordance with an example embodiment of the present invention, one of the first imaging energy emitter  208  and the first imaging receptor  210  is positioned at the first terminal end  204   a  of the support gantry on the folding arm  202 . The first imaging assembly is positioned and oriented, as depicted in  FIGS. 2A-2C , to emit imaging energy (e.g., from the energy emitter  208 ) in an LT plane.  FIGS. 2A-2C  depict the first imaging receptor  210  at the first terminal end  204   a  of the support gantry  204 , however as would be appreciated by one skilled in the art, the first imaging energy emitter  208  could be positioned at the first terminal end  204   a  with the first imaging receptor  210  positioned on the opposite side of the gantry  204  without influencing the imaging process. In other words, the imaging receptor  210  (shown in  FIGS. 2A-2C ) can be switched with the first imaging energy emitter  208  positionally (shown in  FIGS. 2A-2C ). Additionally, as would be appreciated by one skilled in the art, the first imaging assembly can alternatively be positioned and oriented to emit imaging energy (e.g., from the energy emitter  212 ) in an AP plane. 
         [0030]    Continuing with  FIGS. 2A-2C , the apparatus  200  further includes a second imaging assembly positioned on the support gantry  204 , the second imaging assembly including a second imaging energy emitter  212  positioned opposite a second imaging receptor  214 . In accordance with an example embodiment of the present invention, one of the second imaging energy emitter or the second imaging receptor is positioned at the second terminal end  204   b  of the support gantry  204 . The second imaging assembly is positioned and oriented, as depicted in  FIGS. 2A-2C , to emit imaging energy in an AP plane, perpendicular to the LT plane created by the first imaging assembly.  FIGS. 2A-2C  depicts the second imaging receptor  214  at the second terminal end  204   b  of the support gantry  204 , however as would be appreciated by one skilled in the art, the second imaging energy emitter  212  could be positioned at the second terminal end  204   b  with the second imaging receptor  214  positioned on the opposite side of the gantry  204  without influencing the imaging process. In other words, the second imaging receptor  214  (shown in  FIGS. 2A-2C ) can also be switched with the second imaging energy emitter  212  (shown in  FIGS. 2A-2C ) in an optional arrangement. Additionally, as would be appreciated by one skilled in the art, the second imaging assembly can be positioned and oriented to emit imaging energy in an LT plane, perpendicular to the AP plane from the first imaging assembly. 
         [0031]    The apparatus  200  also includes a control unit  216  configured to move and position the support gantry  204  at a desired location. In accordance with an example embodiment of the present invention, the support gantry  204  includes a plurality of wheels  218  to enable a user to push, pull, and pivot the apparatus  200  into a desired position via the control unit  216 . 
         [0032]    In operation, the folding arm  202  can be folded by rotating the folding arm  202  about an X-axis, about the pivot point  202   a , as depicted in  FIGS. 2A-2C . In accordance with an example embodiment of the present invention, the action of the folding arm  202  articulates about the pivot point  202   a  and results in whichever of the first imaging energy emitter  208  or the first imaging receptor  210  (as depicted in  FIGS. 2A-2C ) that is positioned at the first terminal end  204   a  of the support gantry  204  on the folding arm  202  articulating. The articulating motion occurs in a first direction out and away from, or in a second direction in and toward, the center focus point  206  of the generally arc shape support gantry  204 , commensurate with the articulating direction of the folding arm  202  about the pivot point  202   a , as depicted in  FIGS. 2A-2C . By articulating the folding arm  202  out and away from the center focus point  206  to the loading position depicted in  FIG. 2C , the folding arm  202  provides more operating space to eliminate the obstacles between surgeon and nurses under some circumstances and provides easy setup of a patient table to be inserted through the gap created by the articulated folding arm  202 . In particular, the action of the folding arm  202  articulating about the pivot point  202   a  in the direction out and away from the center focus point  206  of the arc shape of the support gantry  204  achieves a sufficiently low position to relative to a height of a surgical table, such that the end portion of the first terminal end  204   a  of the support gantry  204  is foldable to enable rotation of the end portion low enough to adapt to, meaning being just below, a height of an underside of conventional surgical tables. For example, when a user desires to move a surgical table into the G-Arm apparatus  200 , the user can rotate the folding arm  202  to partially or fully folded position, depending on the height of surgical tables, and insert the table above and across the folded down folding arm  202 . Additionally, the G-arm apparatus  200  with the folding arm  202  can adapt to a surgical table such that the G-arm can be positioned (e.g., pushed) underneath the table and is not limited to surgical tables that are only suspended from a single end. In accordance with an example embodiment of the present invention, folding arm  202  includes a rotational joint at the pivot point  206  with a pivot angle ranging between an angles of 0 degrees to 180 degrees. 
         [0033]    As utilized herein, the terms “comprises” and “comprising” are intended to be construed as being inclusive, not exclusive. As utilized herein, the terms “exemplary”, “example”, and “illustrative”, are intended to mean “serving as an example, instance, or illustration” and should not be construed as indicating, or not indicating, a preferred or advantageous configuration relative to other configurations. As utilized herein, the terms “about” and “approximately” are intended to cover variations that may existing in the upper and lower limits of the ranges of subjective or objective values, such as variations in properties, parameters, sizes, and dimensions. In one non-limiting example, the terms “about” and “approximately” mean at, or plus 10 percent or less, or minus 10 percent or less. In one non-limiting example, the terms “about” and “approximately” mean sufficiently close to be deemed by one of skill in the art in the relevant field to be included. As utilized herein, the term “substantially” refers to the complete or nearly complete extend or degree of an action, characteristic, property, state, structure, item, or result, as would be appreciated by one of skill in the art. For example, an object that is “substantially” circular would mean that the object is either completely a circle to mathematically determinable limits, or nearly a circle as would be recognized or understood by one of skill in the art. The exact allowable degree of deviation from absolute completeness may in some instances depend on the specific context. However, in general, the nearness of completion will be so as to have the same overall result as if absolute and total completion were achieved or obtained. The use of “substantially” is equally applicable when utilized in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result, as would be appreciated by one of skill in the art. 
         [0034]    Numerous modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure may vary substantially without departing from the spirit of the present invention, and exclusive use of all modifications that come within the scope of the appended claims is reserved. Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. It is intended that the present invention be limited only to the extent required by the appended claims and the applicable rules of law. 
         [0035]    It is also to be understood that the following claims are to cover all generic and specific features of the invention described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.