Patent Publication Number: US-2016228095-A1

Title: Image guidance system with uer definable regions of interest

Description:
BACKGROUND 
     1. Technical Field 
     This disclosure relates to medical instruments and more particularly to bidirectional data transfer and visualization of real-time interventional information in an ultrasound system. 
     2. Description of the Related Art 
     Ultrasound-guided image interventions allow clinicians to view a patient&#39;s anatomy and interventional devices inserted into the tissue in real time. Image-guided interventional procedures using three-dimensional ultrasound can range from interventions in cardiology, oncology, radiology, etc. In these interventional procedures, two-dimensional or three-dimensional ultrasound images are visualized on the screen of the ultrasound system to guide the clinician in accurately placing interventional devices at target locations in the patient&#39;s anatomy and making intra-procedural real time measurements with sensors embedded on devices, such as catheters, guidewires, etc. While these images can be captured by the ultrasound system and displayed on the ultrasound system screen, the measurements are usually displayed on separate consoles provided by the device manufacturers. 
     SUMMARY 
     In accordance with the present principles, an image guidance system includes an imaging system configured to generate images, the imaging system including a display to permit user selection of areas of interest in the images. One or more objects are visible in the images. A computation engine is configured to combine coordinate systems of the imaging system, the areas of interest, and the one or more objects to provide measurement and/or location information. A bidirectional communication channel is configured to couple the imaging system and the computation engine to permit transmission of the images and the areas of interest to the computation engine and transmission of the measurement and/or location information to the imaging system. 
     A workstation includes a processor and memory coupled to the processor. An imaging system is coupled to the processor and configured to generate images, the imaging system including a display to permit user selection of areas of interest in the images. The memory includes a computation engine configured to combine coordinate systems of the imaging system, the areas of interest, and one or more objects visible in the images to provide measurement and/or location information. The imaging system and computation engine are coupled by a bidirectional communication channel and are configured to permit transmission of the images and the areas of interest to the computation engine and transmission of the measurement and/or location information to the imaging system. 
     A method for image guidance includes generating images of a subject using an imaging system. Areas of interest are selected in the images using a display of the imaging system. Coordinate systems of the imaging system, the areas of interest, and one or more objects visible in the images are combined to provide measurement and/or location information. The images and the areas of interest are transmitted to the computation engine and the measurement and/or location information are transmitted to the imaging system using a bidirectional communication channel coupling the imaging system and the computation engine. 
     These and other objects, features and advantages of the present disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       This disclosure will present in detail the following description of preferred embodiments with reference to the following figures wherein: 
         FIG. 1  is a block/flow diagram showing an image guidance system which employs a bidirectional communication channel to couple an imaging system with computation engine, in accordance with one illustrative embodiment; 
         FIG. 2  is a display of an imaging system showing a critical structure selected by a user, in accordance with one illustrative embodiment; 
         FIG. 3  shows ultrasound images in a multi-planar format, in accordance with one illustrative embodiment; 
         FIG. 4  is a display of an imaging system showing real time sensor data, in accordance with one illustrative embodiment; 
         FIG. 5  shows a spatial bounding box constructed around a region of interest, in accordance with one illustrative embodiment; and 
         FIG. 6  is a block/flow diagram showing a method for image guidance, in accordance with one illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In accordance with the present principles, systems, workstations and methods are provided for image guided interventions. An ultrasound system may be employed to generate three-dimensional ultrasound image streaming in the context of image-guided interventional procedures using a medical device, e.g., needle, catheter, guidewire etc. The interventional procedure may also employ one or more sensors measuring attributes of the tissue, such as, e.g., temperature, contact force, etc. A computation engine registers the imaging coordinate system of the images and the tracking coordinate system of the tracked medical device and tracked sensors into a global coordinate system. The computation engine may construct one or more two-dimensional (2D) planes. Each plane includes an intersection of at least two of: the tracked medical device, sensors, areas of interest (e.g., critical structures), etc. Multiple planes may be generated for each intersection. 
     The ultrasound system may be coupled to a computation engine through a bidirectional communication channel. The bidirectional communication channel permits communication of the images and user selected points and areas of interest from the ultrasound system to the computation engine. The bidirectional communication channel also permits communication of the 2D planes from the computation engine to the ultrasound system, as well as any sensor data. The display of the ultrasound system may visualize imaging data in any of the 2D planes as specified by the data communicated from the computation engine. The sensor data may also be displayed on a display of the ultrasound system. 
     Advantageously, the bidirectional communication channel permits the transmission of data relating to the intervention back into the ultrasound system. In addition, the bidirectional communication channel allows other sources of information, such as, e.g., real time positions of one or more medical devices, distances between real-time positions of medical devices and one or more sensors, distances between real-time positions of interventional devices and user-specified areas of interest (e.g., critical structures in the imaging data), and real-time measurement data from sensors to be displayed back on the screen of the ultrasound system. 
     It should be understood that the present invention will be described in terms of medical instruments; however, the teachings of the present invention are much broader and are applicable to any fiber optic instruments. In some embodiments, the present principles are employed in tracking or analyzing complex biological or mechanical systems. In particular, the present principles are applicable to imaging procedures of biological systems, procedures in all areas of the body such as the lungs, liver, kidney, abdominal region, gastro-intestinal tract, excretory organs, blood vessels, etc. The elements depicted in the FIGS. may be implemented in various combinations of hardware and software and provide functions which may be combined in a single element or multiple elements. 
     The functions of the various elements shown in the FIGS. can be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor (“DSP”) hardware, read-only memory (“ROM”) for storing software, random access memory (“RAM”), non-volatile storage, etc. 
     Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of illustrative system components and/or circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams and the like represent various processes which may be substantially represented in computer readable storage media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. 
     Furthermore, embodiments of the present invention can take the form of a computer program product accessible from a computer-usable or computer-readable storage medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable storage medium can be any apparatus that may include, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), Blu-Ray™ and DVD. 
     Referring now to the drawings in which like numerals represent the same or similar elements and initially to  FIG. 1 , a system  100  for spatial tracking and sensing data integration is illustratively shown in accordance with one embodiment. The system  100  may include a workstation or console  102  from which a procedure is supervised and/or managed. The workstation  102  preferably includes one or more processors  104  and memory  110  for storing programs, applications and other data. 
     The workstation  102  includes a display  106  for viewing, e.g., images or data relating to the procedure. The display  106  may also permit a user to interact with the workstation  102  and its components and functions, or any other element within the system  100 . This is further facilitated by an interface  108  which may include a keyboard, mouse, a joystick, a haptic device, or any other peripheral or control to permit user feedback from and interaction with the workstation  102 . It should be understood that the components and functions of the system  100  may be integrated into one or more systems or workstations, or may be part of a larger system or workstation. 
     The imaging system  124  preferably includes an ultrasound (US) system having a tracked probe or transducer  130  to provide a live stream of two-dimensional (2D) or three-dimensional (3D) volumetric images  114 . It should be understood that imaging system  124  is not limited to an ultrasound system, but rather may include any imaging system, particularly those suitable for real time imaging, such as, e.g., fluoroscopy, etc. The probe  130  is preferably tracked using a tracking device (not shown), such as, e.g., an electromagnetic (EM) tracking device, optical tracking device, etc. The tracking device allows real time spatial tracking of the probe  130  in an imaging tracking system. The imaging tracking system also enables the real time tracking of the position and pose (i.e., orientation) of the medical device  134  in the imaging coordinate system. Spatial tracking information of the probe  130  is stored as probe tracker  118 . 
     The imaging system  124  may include its own display  128  and interface  128  for user interactions. For example, the interface  128  may allow a user to select areas or points of interest on the images as user input  112 . The points of interest may include locations of sensors  138 , critical structures within the subject  132 , etc. as visualized in the images  114 . The user selected points are selected in the imaging tracking system and transmitted to workstation  102 . In one exemplary embodiment, the display  128  may show 3D images in a multi-planar format, i.e., multiple planes (typically 2, but may include more). The 3D images may be sliced along arbitrary, user selected planes. Advantageously, the imaging system  124  is coupled to the workstation  102  via bidirectional communication channel  122 , which is capable of conveying 3D images and metadata (e.g., image related attributes, user selected point coordinates, etc.) to the workstation  102  as images  114  and capable of receiving data in real time from the workstation  102 . 
     Critical structures are sites or regions in the subject  132  (e.g., tissue) that would be adversely affected by the intersection of either the medical device  132 ′s path or by the execution of the desired therapy with the medical device  132  as placed in the desired position. Critical structures may include, e.g., landmarks such as tumor target sites, blood vessel bifurcation points that are useful for the user to determine poisoning information, or other sites of interest. These locations are selected by the user (using interface  128 ) in the imaging coordinate system and communicated to the computation engine  116  for conversion into the global coordinate system. In some embodiments, the computation engine  116  constructs 2D planes representing the location of a tracked medical device  124  in real time in proximity to critical structures. Each plane includes, e.g., an intersection of the tip of the device  134  and the critical structures identified by the user. The 2D planes may be sent to the imaging system  124  over the bidirectional communication cable  122 . This allows the user to make a visual judgment of the suitability of the tracked device trajectory, closeness to targets or reference points like vessel bifurcations, or the degree to which the device  134  is maintained away from the critical structures. 
     Referring for a moment to  FIG. 2 , with continued reference to  FIG. 1 , an exemplary display  126  of the imaging system  124  is shown in accordance with one illustrative embodiment. The display  126  shows a medical device  134  having a tip portion  202 . The display  126  may be used for image guidance of an interventional procedure. A critical structure  204  is selected by a user in the imaging coordinate system. The coordinate information is sent to the computation engine  116 , which converts the coordinate information into the global coordinate system to construct at least one 2D plane showing the intersection of the selected critical structure  204  and tip portion  202 . The 2D plane may also show the intersection between other devices, sensors, areas of interest, etc. 
     Where the user has selected critical structures (e.g., targets, reference points, etc.) or sensors  138 , the display  126  of the imaging system  124  may provide real time distances between the medical device  134  (e.g., tip) and the selected critical structures. The distance may be either from the critical structures to the real time tip location of the medical device  134 , or from the critical structure to the closest point of the device  134 . For example, this allows the user to steer the medical device  134  safely away from critical structures by ensuring some minimal distance is maintained. 
     In some embodiments, the user may be notified if the medical device  134  comes within a predetermined threshold distance to a critical structure. In other embodiments, the user may be notified based on an analysis of the sensor data (e.g., temperature exceeds a user defined threshold, contact force is too small or too large, pressure/flow readings are normal/abnormal, etc.). The notification may include, e.g., an audible alarm, a colored light, a flashing light, a pop up message on a display, a haptic response, etc. 
     Referring back to  FIG. 1 , the computation engine  116  integrates data from probe tracker  118  and measurement tracker  120  with user input  112  and images  114  from the imaging system  124 . The imaging system  124  is coupled to workstation  102  by bidirectional communication channel  122 . The bidirectional communication channel  122  permits external devices to send and receive data relating to the intervention back into the imaging system  124 . Additionally, the bidirectional channel  122  allows other sources of information, such as, e.g., real time position and measurement data from interventional devices, to be displayed back on the display  126  of the imaging system  124 . 
     The imaging system  124  may provide image guidance for interventional procedures involving one or more objects visible in the images  114 . The one or more objects may include devices or instruments  134 , one or more sensors  138 , etc. The device  134  preferably includes a medical device, such as, e.g., a needle, a catheter, a guidewire, a probe, an endoscope, a robot, an electrode, a filter device, a balloon device, or other medical component, etc. The medical device  134  is coupled to the workstation  102  through cabling, which may include fiber optics, electrical connections, other instrumentation, etc. as needed. 
     The medical device  134  may be tracked using tracking device  136  coupled to the medical device  134 . The tracking device  136  may include, e.g., an EM tracking device, optical tracking device, etc. The tracking device  136  enables real time spatial tracking of the medical device  134  when placed into, e.g., the tissue of subject  132  in the spatial tracking system based on the tracking coordinate system. Spatial tracking information of the medical device  134  is stored in measurement tracker  120 . 
     In some embodiments, there may be multiple medical devices  134  inserted into the subject  132 . For example, radiofrequency, cryoablation or microwave ablation proves may be simultaneously present in the tissue of interest. Signals from one or more such devices may provide real time spatial tracking data to the measurement tracker  120 . 
     One or more sensors  138  may be placed within the subject  132 . The sensors  138  may be directly coupled to the tracked medical device  134  or independently placed in the vicinity of the target area (e.g., tissue being treated) of the subject  132 . The sensors  138  are capable of measuring an attribute of the subject  132  (e.g., tissue of the subject  132 ) that may be used for treatment monitoring. The sensors  138  may include, e.g., a temperature sensor, a contact force sensor, flow sensor, etc. The sensors  138  may be capable of sending measurement data in real time to workstation  102  through a wired or wireless interface. If the sensor  138  is coupled to the tracked medical device  134 , sensor data associated with the measurement and spatial tracking information of the medical device  134  may be transmitted to the workstation  102  simultaneously. Sensor data from sensors  138  are also stored in measurement tracker  120 . 
     Sensor data from sensors  138  may be pre-processed by the computation engine  116  to produce a meaningful output for the user. For example, a temperature sensor data may be directly meaningful, whereas an optical spectrum sensor maps a response per wavelength; however, the meaningful output for the user is not the actual raw data of the spectrum but the signal processing of this response to make a tissue classification determination (e.g. tissue classified as healthy, diseased, treated, or untreated). The nature of the pre-processing may depend on the sensor type. The meaningful output is what is sent back to the imaging system  124 . 
     If there are multiple sensors  138  in the vicinity of the tracked medical device  134 , the sensors  138  need to be distinguishable by the user in the images  114  and the identity of each sensor  138  has to be uniquely determined in spatial position. The association of sensors identified in the 3D images  114  and the corresponding data measurement stream is known to the computation engine  116 . The computation engine  116  ensures that data for a sensor is presented in concordance with the 2D plane that includes that sensor. 
     The sensors  138  may or may not be tracked. Non-tracked sensors  138  may be selected by the user (e.g., using interface  128 ) to identify the sensor locations in the imaging data (in the imaging coordinate system). Tracked sensors  138  may involve, e.g., an EM tracking device, optical tracking device, etc. coupled to the sensors  138 . The position of the sensors  138  are tracked in the tracking coordinate system of the tracking device and are reported in real time to the measurement tracker  120 . In this manner, a user does not have to identify the sensor  138  in the images  112  and communicate its coordinates to the computation engine  116 . Tracked sensors  138  synchronously communicates sensor measurement data with the spatial tracking data to the as measurement tracker  120 . 
     The computation engine  116  receives the following signals. 1) 3D images from the imaging system  124 , having a coordinate system (i.e., imaging coordinate system) relative to an arbitrary but fixed point on the probe  130  (e.g., center of the surface of the probe  130 ). 2) Spatial locations of user selected (user identified) sensors  138  in the imaging coordinate system. 3) Real time spatial tracking information from medical device  134 , which are in the coordinate frame of the tracking system  136  (i.e., tracking coordinate system). 4) Real time data measurements from sensors  138 . 5) Optionally, real time spatial tracking information from other tracked devices or sensors  138  in or around the target area where the 3D images  114  and medical device  134  are located in the tracking coordinate system. 
     The computation engine  116  combines the images  114  and real time spatially tracked data into a single global coordinate system using spatial registration techniques. The spatial registration combines the imaging coordinate system (from, e.g., imaging data, selected critical structures, selected sensors, etc.) and tracking coordinate system (from, e.g., tracked medical device  134 , tracked sensors  138 , etc.) into the global coordinate system. For example, images  114  of the imaging coordinate system may be mapped to the tracking coordinate system using a calibration transform (typically a 4×4 matrix), or vice versa. In another example, the location of the sensor  138  in the imaging coordinate system may be mapped to the tracking coordinate system. Other approaches to registration are also contemplated. 
     Once all images and device/sensor locations are defined in the global coordinate system, the computation engine  116  defines poses (i.e., positions and orientations) of the device  134  and sensors  138  in 2D planes from the 3D images. The computation engine  116  may use the tip location of the device  134 , its orientation, and one or more locations of the sensors  138  to define the poses. For example, a 2D plane can be constructed that shows the entire axis of the device  134  along with its tip in the 3D image. However, there is still one degree of freedom to define in this plane to allow a complete rotation around the axis. The plane can be locked to include a rotation angle around the axis of device  134  that also allows one sensor  138  position to be in-plane. This ensures the tip and shaft of device  134  and one sensor  138  are in one 2D plane. The pose of this plane may be updated with real time spatial tracked position of the device  134  and sensor  138 . The computation engine  116  may construct additional planes showing a coplanar intersection between additional devices, sensors, areas of interest, etc. In some embodiments, the computation engine  116  represents the tracked device  134  and/or sensors  138  as virtual objects fused shown on display  126  with or overlaid on the live imaging data, since these instruments and sensors may not be clearly visible in the imaging data itself. 
     The computation engine  116  uses the bidirectional communication channel  122  to communicate the 3D poses of the 2D planes to the imaging system  124  using the imaging coordinate system. The bidirectional communication channel  122  may be wireless, wired, or a part of a larger cable. If the poses were calculated in the tracking coordinate system, the appropriate conversion may be applied to the pose. The imaging system  124  receives the poses of the 2D planes and calculates the corresponding 2D image from the 3D images as intersected by the 2D plane. The one or more 2D images corresponding to the poses of the 2D planes are displayed on display  126  of the imaging system  124 . 
     Referring for a moment to  FIG. 3 , with continued reference to  FIG. 1 , ultrasound images  300  are shown in a multi-planar format, in accordance with one illustrative embodiment. Two 2D ultrasound images are simultaneously displayed on an ultrasound display, such as the display  126 . The ultrasound image includes a first 2D plane  302  and a second 2D plane  304 . A medical device  312  having a tip portion  306  may be positioned within a subject (e.g., patient). A sensor  308  and critical structure  310  are located within the vicinity of the target area. The sensor  308  and critical structure  310  may be selected by a user such that the two planes  302 ,  304  include a selection of the tip portion  306  and shaft of the device  304  with either a user selected sensor  308  or a critical structure  310 . 
     Referring back to  FIG. 1 , the bidirectional communication channel  122  is used to transmit real time (pre-processed) measurement data from sensors  138  to the imaging system  124 . The imaging system  124  may display the corresponding real time sensor measurement data in a graphical user interface appropriate to the measurement type being shown. This may involve display  126  and/or interface  128 . The measurement data may be displayed according to a selection of a sensor by the user or automatically depending on which sensors are relevant. Relevant sensors may be determined based on which user-identified critical structures or other structures of interest are present in the visualization at any moment. 
     Referring for a moment to  FIG. 4 , with continued reference to  FIG. 1 , an exemplary display  126  of the imaging system  124  is shown in accordance with one illustrative embodiment. The display  126  shows a medical device  134  having a tip portion  402 . A sensor  138  is selected by a user such that at least one 2D plane includes the sensor  138  with the tip portion  402 . The sensor&#39;s data can be communicated in real time and visualized on the display  126  as real time sensor value  404 . 
     Referring back to  FIG. 1 , in some embodiments, a spatial bounding box may be constructed. A spatial bounding box is a 3D volume containing a region of interest to the user. Typically, this region of interest includes the tip of device  134 , a portion of the shaft of the device  134  close to the tip, and one or more sensors  138  all within the bounding box. The coordinates of the spatial bounding box may be transmitted to the imaging system  124  through bidirectional communication channel  122 . 
     The imaging system  124  receives coordinates of the spatial bounding box and determines a 3D sub-volume of the 3D ultrasound image. This allows the ultrasound system to optimally render only the sub-volume view and 2D planes within the sub-volume. The signal processing attributes, such as, e.g., gain, focus, depth, time-gain-compensation (TGC), frame rate, visualization enhancement, etc., of the display  126  of the imaging system  124  can be dynamically optimized according to the sub-volume locations. Higher frame rates of 3D acquisition may be possible when the 3D region of interest is known to the imaging system. 
     Referring for a moment to  FIG. 5 , with continued reference to  FIG. 1 , areas of interest within a spatial bounding box  500  is shown in accordance with one illustrative embodiment. The spatial bounding box  502  is constructed around a region on interest. The region of interest includes a tip portion  504  of a medical device  514 , critical structure  508  and sensor  506  locations. The bounding box coordinates are communicated to the imaging system using the bidirectional communication channel  122  allowing the imaging system to optimize the view within the bounding box. The bounding box  502  includes a first 2D plane  510  and a second 2D plane  512 . The sensor  506  and critical structure  508  may be selected by a user such that the two planes  510 ,  512  include a selection of the tip portion  504  with either a user selected sensor  506  or a critical structure  508 . 
     Referring now to  FIG. 6 , a block/flow diagram showing a method for image guidance  600  is illustratively depicted in accordance with one embodiment. In block  602 , images (e.g., 3D) of a subject (e.g., patient, volume, etc.) are generated using an imaging system. The imaging system preferably includes an ultrasound system having a tracked probe. In block  604 , areas of interest in the images are selected using a display of the imaging system. Areas of interest may include (non-tracked) sensors, critical structures, etc. 
     In block  606 , coordinate systems of the imaging system, the areas of interest, and one or more objects visible in the images are combined to provide measurement and/or location information. The one or more objects may include one or more devices (e.g., medical instruments), one or more sensors, etc. Measurement and/or location information may include visualization information, data from a sensor, etc. The imaging data and areas of interest identified in the imaging data as selected by the user (e.g., non-tracked sensors, critical structures) are tracked in an imaging coordinate system. The spatial locations of the tracked device and tracked sensors are tracked in a tracking coordinate system. In block  608 , combining includes registering the coordinate systems of the imaging system, the areas of interest, and the one or more objects to a global coordinate system to provide the measurement and/or location information. 
     In block  610 , one or more 2D planes are constructed such that each 2D plane shows an intersection of at least two or more of: the one or more objects (e.g., devices, sensors, etc.) and the areas of interest (e.g., critical structures, points of interest, etc.). In some embodiments, a spatial bounding box is constructed for a target area in the 2D planes. The target area may include the tracked device, one or more sensors, areas of interest, etc. In block  612 , the one or more objects may be represented as virtual objects in the display of the imaging system. In block  614 , a notification is generated. The notification may be based on a distance between the one or more objects and areas of interest or based on the data of the one or more sensors. 
     In block  616 , the 3D images and the user selection are transmitted to the computation engine and the measurement and/or location information are transmitted to the imaging system using a bidirectional communication channel. The bidirectional communication channel couples the imaging system and the computation engine, allowing sources of information to be displayed on the imaging system. 
     In interpreting the appended claims, it should be understood that:
         a) the word “comprising” does not exclude the presence of other elements or acts than those listed in a given claim;   b) the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements;   c) any reference signs in the claims do not limit their scope;   d) several “means” may be represented by the same item or hardware or software implemented structure or function; and   e) no specific sequence of acts is intended to be required unless specifically indicated.       

     Having described preferred embodiments for bidirectional data transfer and visualization of real-time interventional information in an ultrasound system (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the disclosure disclosed which are within the scope of the embodiments disclosed herein as outlined by the appended claims. Having thus described the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.