Patent Publication Number: US-2021161601-A1

Title: Affected region display associated with a medical device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/882,709, filed Jan. 29, 2018, entitled AFFECTED REGION DISPLAY BASED ON A VARIANCE PARAMETER ASSOCIATED WITH A MEDICAL DEVICE, which is a continuation of U.S. patent application Ser. No. 14/872,930, filed Oct. 1, 2015, entitled AFFECTED REGION DISPLAY ASSOCIATED WITH A MEDICAL DEVICE, which claims priority benefit to U.S. Provisional Application No. 62/059,077, filed Oct. 2, 2014, entitled ABLATION AREA VISUALIZATIONS, each of which is hereby incorporated herein by reference in its entirety. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are incorporated by reference under 37 CFR 1.57 and made a part of this specification. 
    
    
     TECHNICAL FIELD 
     The systems and methods disclosed herein relate generally to computer systems facilitating medical device guidance through tissue by a medical practitioner. 
     BACKGROUND 
     Various medical device systems are available to aid a healthcare provider to guide a medical device in a patient. The medical device systems can provide various image guidance cues to aid the healthcare provider, and can also provide views of images of an imaged area and of virtual medical devices corresponding to physical medical devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an embodiment of a system for image-guided medical procedures. 
         FIG. 2  is a diagram of an embodiment of a rendering of image guidance cues and medical display objects on a display. 
         FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I, and 3J  are diagrams illustrating embodiments of displayed affected regions. 
         FIGS. 4A, 4B, and 4C  are diagrams illustrating embodiments of surface display regions. 
         FIGS. 5A, 5B, and 5C  are diagrams illustrating embodiments of displayed affected regions, including surface display regions. 
         FIG. 6  is a flow diagram illustrative of an embodiment of a routine implemented by the system to display a displayed affected region. 
         FIG. 7  is a flow diagram illustrative of an embodiment of a routine implemented by the system to display displayed affected regions. 
     
    
    
     DETAILED DESCRIPTION 
     Implementations disclosed herein provide systems, methods, and apparatus for generating images facilitating medical device insertion into tissue by an operator. Certain embodiments pertain to a free-hand medical device guidance system. The system can provide the healthcare provider manual control over the medical device, while making the spatial relationships between the target, medical device and U/S image more intuitive via a visual display. Using this visual feedback, the operator can adjust the medical device&#39;s position, orientation, or trajectory. Certain of the contemplated embodiments can be used in conjunction with systems described in greater detail in U.S. patent application Ser. No. 13/014,587, filed Jan. 26, 2011, entitled SYSTEMS, METHODS, APPARATUSES, AND COMPUTER-READABLE MEDIA FOR IMAGE MANAGEMENT IN IMAGE-GUIDED MEDICAL PROCEDURES and U.S. patent application Ser. No. 13/753,274, filed Jan. 29, 2013, entitled MULTIPLE MEDICAL DEVICE GUIDANCE (the &#39;274 Application), and U.S. patent application Ser. No. 14/212,933, filed Mar. 14, 2014, entitled MEDICAL DEVICE GUIDANCE, each of which is hereby incorporated by reference in its entirety. 
     The system can aid the healthcare provider in guiding one or more medical devices through the tissue of the patient and/or placing the medical devices, and can be used for treatment of tumors, fibroids or cysts, with bipolar radiofrequency medical device ablation, multiple microwave medical devices, electroporation, and/or electrochemotherapy systems. It can also be used for nerve or muscle stimulation or sensing (electrodes in the spine, brain). The system can be used during open surgery, laparoscopic surgery, endoscopic procedures, biopsies, and/or interventional radiology procedures. 
     The system can be used in conjunction with live intraoperative ultrasound (U/S), pre-operative CT, or any cross-sectional medical imaging modality (e.g. MRI, OCT, etc.). In addition, the system can use a variety of techniques to determine the position and/or orientation of one or more medical devices. For example, the system can use the NDI Aurora magnetic system, NDI Polaris optical system, etc. In some embodiments, a position sensor can be embedded inside, or affixed to each medical device, at the tip, along the shaft, and/or on the handle. Sensors can be built into the medical devices or attached after manufacturing, as described in greater detail in U.S. application Ser. No. 14/212,184, filed Mar. 14, 2014, entitled SENSOR MOUNT, incorporated herein in its entirety. 
     Each medical device can be associated with one or more sensors, which can continually, or repeatedly, report position and/or orientation, or a single sensor can be used for all the medical devices. In embodiments where one sensor is used, the healthcare provider can attach the sensor to the particular medical device that she is intentionally repositioning, and then, once she has placed that medical device, she can remove the sensor and attach it to the next medical device she is repositioning. In some embodiments, the medical devices can be manipulated by the healthcare provider. In certain embodiments, the system can be used with a robotic manipulator, where the robot controls the medical devices. 
     In some embodiments, the handles of medical devices can have push-button switches, to allow the user to select a medical device, indicate a tissue target, etc. The handle can also have an indicator light to indicate to the users which medical device is selected. Finally, the handle can have an encoder to detect how much length of electrode has been exposed by the user, and report this information to the guidance system and therapeutic generator 
     Image Guidance Systems 
       FIG. 1  is a diagram illustrating an embodiment of a system for image management in image-guided medical procedures. In some embodiments, the position sensing unit  140  can track surgical instruments, also referred to herein as medical devices, within a tracking area and provide data to the image guidance unit  130 . The medical devices can include invasive medical devices, such as, but not limited to, biopsy needles, ablation needles, surgical needles, nerve-block needles, or other needles, electrocautery device, catheters, stents, laparoscopes or laparoscopic cameras, ultrasound transducers, or other instruments that enter a part of the body, and non-invasive medical devices that do not enter the body, such as, but not limited to, ultrasound transducers, probes, or other external imaging devices, etc. The medical devices can also include medical imaging devices that provide or aid in the selection of medical images for display. In some embodiments, the medical imaging device can be any device that is used to select a particular medical image for display. The medical imaging devices can include invasive medical devices, such as laparoscopic cameras, and non-invasive medical devices, such as external ultrasound transducers. 
     Although only two surgical instruments  145  and  155  are shown in  FIG. 1 , it will be understood that additional surgical instruments can be tracked and associated data can be provided to the image guidance unit  130 . The image guidance unit  130  can process or combine the data and show image guidance data on display  120 . This image guidance data can be used by a healthcare provider to guide a procedure and improve care. There are numerous other possible embodiments of system  100 . For example, many of the depicted components can be joined together to form a single component and can be implemented in a single computer or machine. Further, additional position sensing units can be used in conjunction with position sensing unit  140  to track all relevant surgical instruments  145  and  155 , as discussed in more detail below. Additional imaging units  150  can be included, and combined imaging data from the multiple imaging units  150  can be processed by image guidance unit  130  and shown on display unit  120 . Additionally, two or more surgical systems  149  can also be included. 
     Information about and from multiple surgical systems  149  and attached surgical instruments  145  (and additional surgical instruments not shown) can be processed by image guidance unit  130  and shown on display  120 . These and other possible embodiments are discussed in more detail below. It will be understood that any combination of the display objects, image guidance cues, etc., described herein can be displayed concurrently, or simultaneously. Further, reference to displaying objects “concurrently” and/or “simultaneously” is to be interpreted broadly and may refer to displaying objects in such a way that to a human observer the objects are visible at the same time. 
     Imaging unit  150  can be coupled to image guidance unit  130 . In some embodiments, imaging unit  150  can be coupled to a second display unit (not shown). The second display unit can display imaging data from imaging unit  150 . The imaging data displayed on display unit  120  and displayed on second display unit can be the same or different. In some embodiments, the imaging unit  150  is an ultrasound machine  150 , the movable imaging device  155  is an ultrasound transducer  155  or ultrasound probe  155 , and the second display unit is a display associated with the ultrasound machine  150  that displays the ultrasound images from the ultrasound machine  150 . In some embodiments, a movable imaging unit  155  can be connected to image guidance unit  130 . The movable imaging unit  155  can be useful for allowing a user to indicate what portions of a first set of imaging data are to be displayed. For example, the movable imaging unit  155  can be an ultrasound transducer  155 , a needle or other medical device, for example, and can be used by a user to indicate what portions of imaging data, such as a pre-operative CT scan, to show on a display unit  120  as image  125 . Further, in some embodiments, there can be a third set of pre-operative imaging data that can be displayed with the first set of imaging data. 
     In some embodiments, system  100  comprises a display unit  120  and a position sensing unit  140  communicatively coupled to image guidance unit  130 . In some embodiments, position sensing unit  140 , display unit  120 , and image guidance unit  130  are coupled to the stand  170 . Image guidance unit  130  can be used to produce images  125  that are displayed on display unit  120 . The images  125  produced on display unit  120  by the image guidance unit  130  can be determined based on ultrasound or other visual images from the first surgical instrument  145  and second surgical instrument  155 . In the illustrated embodiment, the images  125  includes a 2D viewing area and a 3D viewing area. The 2D viewing area includes a 2D view of each of an ultrasound slice  121 , a virtual medical device  122  corresponding to the first surgical instrument  145 , a virtual imaging device  123  corresponding to the second surgical instrument  155 , surface display regions  124   a,    124   b,  intersection indicator  126 , and trajectory and other image guidance cues  127 . In the illustrated embodiment, the 3D viewing area includes perspective views of each of the image slice  121 , the virtual medical device  122 , a displayed affected region  129  including the surface display regions  124   a,    124   b,  the virtual imaging device  123 , intersection indicator  126 , trajectory and other image guidance cues  127 , and a patient orientation indicator  128 . It will be understood that any combination of the aforementioned display objects can be displayed in the 2D view and/or 3D view as desired. 
     As a non-limiting example, if the first surgical instrument  145  is an ablation needle  145  and the second surgical instrument  155  is an ultrasound probe  155 , then images  125  produced on display  120  can include the images, or video, from the ultrasound probe  155  (e.g., image slice  121 ) combined with other medical display objects and image guidance cues, such as projected medical device drive (e.g., trajectory indicators  127 ) or projected ablation volume (e.g., displayed affected region  129 ), determined based on the emplacement of ablation needle  145 . If the first surgical instrument  145  is an ultrasound probe  145  and the second surgical instrument  155  is a laparoscopic camera  155 , then images  125  produced on display  120  can include the video from the laparoscopic camera  155  combined with ultrasound data superimposed on the laparoscopic image. More surgical instruments can be added to the system. For example, the system can include an ultrasound probe, ablation needle, laparoscopic camera, stapler, cauterizer, scalpel and/or any other surgical instrument or medical device. The system can also process and/or display collected data, such as preoperative CT scans, X-Rays, MRIs, laser scanned 3D surfaces etc. 
     The term “emplacement” as used herein is a broad term and may refer to, without limitation, position and/or orientation or any other appropriate location information. The term “pose” as used herein is a broad term encompassing its plain and ordinary meaning and may refer to, without limitation, position and orientation or any other appropriate location information. In some embodiments, the imaging data obtained from one or both of surgical instruments  145  and  155  can include other modalities such as a CT scan, MRI, open-magnet MRI, optical coherence tomography (“OCT”), positron emission tomography (“PET”) scans, fluoroscopy, ultrasound, or other preoperative, or intraoperative 2D or 3D anatomical imaging data. In some embodiments, surgical instruments  145  and  155  can also be scalpels, implantable hardware, or any other device used in surgery. Any appropriate surgical system  149  or imaging unit  150  can be attached to the corresponding medical instruments  145  and  155 . 
     As noted above, images  125  produced can also be generated based on live, intraoperative, or real-time data obtained using the second surgical instrument  155 , which is coupled to second imaging unit  150 . The term “real time” as used herein is a broad term and has its ordinary and customary meaning, including without limitation instantaneously or nearly instantaneously. The use of the term real time can also mean that actions are performed or data is obtained with the intention to be used immediately, upon the next cycle of a system or control loop, or any other appropriate meaning. Additionally, as used herein, real-time data can be data that is obtained at a frequency that would allow a healthcare provider to meaningfully interact with the data during surgery. For example, in some embodiments, real-time data can be a medical image of a patient that is updated one time per second. In some embodiments, real-time data can be ultrasound data that is updated multiple times per second. 
     The surgical instruments  145 ,  155  can be communicatively coupled to the position sensing unit  140  (e.g., sensors embedded or coupled to the surgical instruments  145 ,  155  can be communicatively coupled with the position sensing unit  140 ). The position sensing unit  140  can be part of imaging unit  150  or it can be separate. The position sensing unit  140  can be used to determine the emplacement of first surgical instrument  145  and/or the second surgical instrument  155 . In some embodiments, the position sensing unit  140  can include a magnetic tracker and/or one or more magnetic coils can be coupled to surgical instruments  145  and/or  155 . In some embodiments, the position sensing unit  140  can include an optical tracker and/or one or more visually-detectable fiducials can be coupled to surgical instruments  145  and/or  155 . In some embodiments, the position sensing unit  140  can be located below the patient. In such embodiments, the position sensing unit  140  can be located on or below the table  180 . For example, in embodiments where the position sensing unit  140  is a magnetic tracker, it can be mounted below the surgical table  180 . Such an arrangement can be useful when the tracking volume of the position sensing unit  140  is dependent on the location of the position sensing unit  140 , as with many magnetic trackers. In some embodiments, magnetic tracking coils can be mounted in or on the medical devices  145  and  155 . 
     In some embodiments, the position sensing unit  140  can be an electromagnetic measurement system (e.g., NDI Aurora system) using sensor coils for tracking units attached to the first and/or second surgical devices  145  and  155 . In some embodiments, the second position sensing unit  140  can be an optical 3D tracking system using fiducials. Such optical 3D tracking systems can include the NDI Polaris Spectra, Vicra, Certus, PhaseSpace IMPULSE, Vicon MX, InterSense IS-900, NaturalPoint OptiTrack, Polhemus FastTrak, IsoTrak, or Claron MicronTracker2. In some embodiments, the position sensing unit  140  can each be an inertial 3D tracking system comprising a compass, accelerometer, tilt sensor, and/or gyro, such as the InterSense InertiaCube or the Nintendo Wii controller. In some embodiments, the position sensing unit  140  can be attached to or affixed on the corresponding surgical device  145  and  155 . 
     In some embodiments, the position sensing units  140 , can include sensing devices such as the HiBall tracking system, a GPS device, or signal emitting device that would allow for tracking of the position and/or orientation (e.g., emplacement) of the tracking unit (also referred to as an emplacement sensor). In some embodiments, a position sensing unit  140  can be affixed to either or both of the surgical devices  145  and  155 . The surgical devices  145  or  155  can be tracked by the position sensing unit  140 . A room coordinate system reference, such as the display  120  can also be tracked by the position sensing unit  140  in order to determine the emplacements of the surgical devices  145  and  155  with respect to the room coordinate system. Devices  145  and  155  can also include or have coupled thereto one or more accelerometers, which can be used to estimate movement, position, and location of the devices. 
     In some embodiments, the position sensing unit  140  can be an Ascension Flock of Birds, Nest of Birds, driveBAY, medSAFE, trakSTAR, miniBIRD, MotionSTAR, pciBIRD, or Calypso 2D Localization System and tracking units attached to the first and/or second medical devices  145  and  155  can be magnetic tracking coils. 
     The term “tracking unit” (also referred to as an emplacement sensor), as used herein, is a broad term encompassing its plain and ordinary meaning and includes without limitation all types of magnetic coils or other magnetic field sensing devices for use with magnetic trackers, fiducials or other optically detectable markers for use with optical trackers, such as those discussed above and below. In some embodiments, the tracking units can be implemented using optical position sensing devices, such as the HiBall tracking system and the position sensing unit  140  can form part of the HiBall tracking system. Tracking units can also include a GPS device or signal emitting device that allows for tracking of the position and/or orientation of the tracking unit. In some embodiments, a signal emitting device might include a radio-frequency identifier (RFID). In such embodiments, the position sensing unit  140  can use the GPS coordinates of the tracking units or can, for example, triangulate the radio frequency signal being emitted by the RFID associated with tracking units. The tracking systems can also include one or more 3D mice. 
     Images  125  can be produced based on intraoperative or real-time data obtained using first surgical instrument  145 , which is coupled to first surgical system  149 . In the illustrated embodiment of  FIG. 1 , the first surgical system  149  is shown as coupled to image guidance unit  130 . The coupling between the first surgical system  149  and image guidance unit  130  may not be present in all embodiments. In some embodiments, the coupling between first surgical system  149  and image guidance unit  130  can be included where information about first surgical instrument  145  available to first surgical system  149  is useful for the processing performed by image guidance unit  130 . For example, in some embodiments, the first surgical instrument  145  is an ablation needle  145  and first surgical system  149  is an ablation system  149 . In some embodiments, it can be useful to send a signal about the relative strength of planned ablation from ablation system  149  to image guidance unit  130  in order that image guidance unit  130  can show a predicted ablation volume. In other embodiments, the first surgical system  149  is not coupled to image guidance unit  130 . Example embodiments including images and graphics that can be displayed are included below. 
     In some embodiments, the display unit  120  displays 3D images to a user, such as a healthcare provider. Stereoscopic 3D displays separate the imagery shown to each of the user&#39;s eyes. This can be accomplished by a stereoscopic display, a lenticular auto-stereoscopic display, or any other appropriate type of display. The display  120  can be an alternating row or alternating column display. Example alternating row displays include the Miracube G240S, as well as Zalman Trimon Monitors. Alternating column displays include devices manufactured by Sharp, as well as many “auto-stereoscopic” displays (e.g., Philips). In some embodiments, Sony Panasonic 3D passive displays and LG, Samsung, and/or Vizio 3D TVs can be used as well. Display  120  can also be a cathode ray tube. Cathode Ray Tube (CRT) based devices, can use temporal sequencing, showing imagery for the left and right eye in temporal sequential alternation. This method can also be used projection-based devices, as well as by liquid crystal display (LCD) devices, light emitting diode (LED) devices, and/or organic LED (OLED) devices. 
     In certain embodiments, the display unit  120  can be a head mounted display worn by the user in order to receive 3D images from the image guidance unit  130 . In such embodiments, a separate display, such as the pictured display unit  120 , can be omitted. The 3D graphics can be produced using underlying data models, stored in the image guidance unit  130  and projected onto one or more 2D planes in order to create left and right eye images for a head mount, lenticular, or other 3D display. The underlying 3D model can be updated based on the relative emplacements of the various devices  145  and  155 , as determined by the position sensing unit(s)  140 , and/or based on new data associated with the devices  145  and  155 . For example, if the second medical device  155  is an ultrasound probe, then the underlying data model can be updated to reflect the most recent ultrasound image. If the first medical device  145  is an ablation needle, then the underlying model can be updated to reflect any changes related to the needle, such as power or duration information. Any appropriate 3D graphics processing can be used for rendering including processing based on OpenGL, Direct3D, Java 3D, etc. Whole, partial, or modified 3D graphics packages can also be used, such packages including 3DS Max, SolidWorks, Maya, Form Z, Cybermotion 3D, VTK, Slicer, or any others. In some embodiments, various parts of the needed rendering can occur on traditional or specialized graphics hardware. The rendering can also occur on the general CPU, on programmable hardware, on a separate processor, be distributed over multiple processors, over multiple dedicated graphics cards, or using any other appropriate combination of hardware or technique. 
     One or more components, units, devices, or elements of various embodiments can be packaged and/or distributed as part of a kit. For example, in one embodiment, an ablation needle, one or more tracking units, 3D viewing glasses, and/or a portion of an ultrasound wand can form a kit. Other embodiments can have different elements or combinations of elements grouped and/or packaged together. Kits can be sold or distributed separately from or with the other portions of the system. 
     One will readily recognize that there are numerous other examples of image guidance systems which can use, incorporate, support, or provide for the techniques, methods, processes, and systems described herein. 
     Depicting Surgical Instruments 
     It can often be difficult to discern the content of a 3D scene from a 2D depiction of it, or even from a 3D depiction of it. Therefore, various embodiments herein provide image guidance that can help the healthcare provider better understand the scene, relative emplacements or poses of object in the scene and thereby provide improved image guidance. 
       FIG. 2  illustrates a perspective view of a virtual rendering  202  of a surgical instrument  242  being displayed on a screen  220  with a perspective view of a medical image  204 . In some embodiments, the screen  220  can correspond to the screen of a display unit  120 , which can be implemented using a TV, computer screen, head-mounted display, projector, etc. In the illustrated embodiment, the rendered surgical instrument  202  displayed on the screen  220  corresponds to the ablation needle  242 . A wire  246  connecting the ablation needle  242  to an ablation system is also depicted in  FIG. 2 . 
     Although only one virtual surgical instrument  202  is displayed, it will be understood that multiple medical devices can be tracked and displayed concurrently, or simultaneously, on screen  220 , as described in greater detail in the &#39;274 Application, previously incorporated by reference. For example, a virtual rendering of the medical imaging device  222  can be displayed. 
     The virtual surgical instrument  202  can be displayed in a virtual 3D space with the screen  220  acting as a window into the virtual 3D space. Thus, as the surgical instrument  242  is moved to the right with respect to a point-of-view location (e.g., the location of the point-of-view for viewing the 3D space), the virtual surgical instrument  202  also moves to the right. Similarly, if the surgical instrument  242  is rotated 90 degrees so that the tip of the surgical instrument is pointing away from the point-of-view location (e.g., at the screen  220 ), the virtual surgical instrument  201  will likewise show the change in orientation, and show the tip of the virtual surgical instrument  202  in the background and the other end of the virtual surgical instrument  202  in the foreground. In some embodiments, as described in greater detail in U.S. application Ser. No. 14/212,933, incorporated herein by reference in its entirety, the point-of-view location can be a fixed location, such as a predetermined distance/angle from the screen  220  or stand  170  and or a location configured by the user; or the point-of-view location can by dynamic. For example, the system can track a user in real-time and determine the point-of-view location based at least in part on the tracked location of the user. 
     Some models of medical devices have markings such as bands around the shaft (to indicate distance along the shaft), and a colored region  203  near the tip to indicate from where the radio frequency or microwave energy is emitted in the case of an ablation probe. Healthcare providers performing medical device procedures are often familiar with these markings and can use them to help understand the spatial relationship between the medical device and anatomy. In some embodiments, the make and model of the medical device  242  is known to the image guidance system and the virtual medical device  202  displayed in display  220  can resemble medical device  242 . The features of medical devices that can be rendered in the scene include the overall shape (diameter, cross sectional shape, curvature, etc.), color, distance markers, visuals or echogenic fiduciary markers, the state of deployable elements such as tines, paddles, anchors, resection loops, stiffening or steerable sleeves, temperature, radiation, light or magnetic field sensors, lens, waveguides, fluid transfer channels, and the like. 
     The type of medical device being used can be input into the image guidance system  100 , can be a system default, can be detected by a camera or other device, can be received as data from an attached medical device, such as surgical system  149  in  FIG. 1 , or the information can be received in any other appropriate manner. Displaying on display  220 , a virtual surgical instrument that resembled the surgical instrument  242  can help healthcare providers associate the image guidance data with the real world and can provide more familiar guidance information to a healthcare provider, thereby further aiding the healthcare provider in the guidance task. For example, the healthcare provider can see the familiar markings on the medical device being displayed on the display  220  and therefore be familiar with the distance and relative placement of the displayed medical device with respect to other data, such as a tumor  212  seen in a rendered ultrasound image  204 ,  205 . This knowledge of relative placement of items being displayed can help the healthcare provider move the medical device into place. 
     Consider an embodiment in which the virtual surgical instrument  202  in the display  220  is an ablation needle depicting the portion of the needle that will perform the ablation, for example, the portion that emits the radio or microwave energy. If the display  220  also includes ultrasound data, then the doctor can be able to find the tumor  212  she wishes to ablate by moving the ultrasound probe around until she spots the tumor  212 . In various embodiments, she will be able to see the displayed ultrasound data and its location relative to the displayed medical device with the markings. She can then drive the medical device until she sees, on display  220 , that the emitter-portion of the medical device encompasses the tumor in the ultrasound, also seen on display  220 . When she activates the ablation, she can then be much more certain that she has ablated the correct portion of the tissue. Various embodiments of this are discussed below. 
     As another example, consider the physical markings that can be on the instruments themselves. These markings can help orient a healthcare provider during use of the instrument. In some embodiments, the image guidance unit can represent these markings in the images displayed in the display. For example, certain ultrasound transducers are built with an orientation mark (e.g., a small bump) on one side of the transducing array. That mark can also be shown in the ultrasound image on the scanner&#39;s display, to help the healthcare provider understand where the scanned anatomical structures shown on screen are located under the transducer, inside the patient. In some embodiments, the image guidance system can display a symbolic 3D representation of the orientation mark both next to the motion-tracked ultrasound slice (e.g., moving with the displayed ultrasound slice) and next to the 2D view of the ultrasound slice also displayed by the system. An example of this is displayed in  FIG. 2 , where a small rectilinear volume  214  corresponding to a feature on an ultrasound probe is shown both in proximity to the ultrasound slice displayed in the 3D view and the ultrasound slice displayed in a 2D view. 
     It will be understood that an image slice can correspond to image data received from an imaging device, such as an ultrasound transponder. In some embodiments, the image data can correspond to a cross-section of tissue having a certain thickness. In some instances, the imaging device can compact the image data, and/or treat the image data as 2D data, such that there is no perceived thickness. In certain embodiments, when the image slice is displayed in a 3D view, the system can treat the image slice as a 2D or quasi 2D object. In such embodiments, the system can cause the image slice to have little to no perceptible thickness. Accordingly, in certain embodiments, when the image slice is oriented orthogonally or perpendicularly with respect to the point-of-view location, the system can cause the display to display nothing or a line having a relatively small thickness, such as a few pixels, etc. In some cases, the number of pixels used to display the relatively small thickness of the image slice can correspond to the size of the display. For example, more pixels can be used for a larger display and fewer pixels can be used for a smaller display, etc. 
     Other embodiments can track and display other types of instruments and their features. For example, a healthcare provider may want to track one or more of a scalpel, a biopsy, a cauterizer (including an electrocauterizer and Bovies), forceps, cutting loops on hysteroscopes, harmonic sheers, lasers (including CO 2  lasers), etc. For example, in various embodiments, the following devices can be tracked and various aspects of their design displayed on display  220 : Olympus™ OES Pro Hystero-Resectoscope, SonoSurg Ultrasonic Surgical System Olympus™ GF-UC 160 Endoscope Wallus™ Embryo Transfer Catheter AngioDynamics® NanoKnife™, VenaCure™ laser, StarBurst, Uniblade, Habib® Resector Bovie™ Electrodes, Covidien Evident™, Cool-tip™ Ablation Antennas, Opti4™ Electrodes Microsulis MEA (microwave endometrial ablation), Acculis Halt™ Medical System Optimed BigLumen Aspiration Catheter Optimed Optipure Stent Central venous catheterization introducer medical device (such as those made by Bard and Arrow). 
     Once tracked, a healthcare provider is able to see image guidance data on display  220  that will allow her to know the relative pose, location, or emplacement of the tracked instrument(s) with respect to one another or with respect to imaging data and will be able to see, on display  220 , the features of the instrument rendered in the scene. 
     Depicting Medical Device Placement, Trajectory, and Other Image Guidance Cues 
     In certain procedures, the system can provide image prediction information related to the surgical instruments as image guidance cues. In the context of scalpel movement, this can be the location that the scalpel will hit if a healthcare provider continues to move the scalpel in a particular direction. In the context of ablation or biopsies, this can be the projected medical device placement if it is driven along its central axis, which is also referred to herein as a longitudinal axis. 
       FIG. 2  further illustrates an embodiment of a projected needle drive  208  (also referred to as a trajectory indicator) as an image guidance cue. If a healthcare provider is driving an ablation needle  242  into tissue (not pictured), then she can know where the medical device will be driven. In some embodiments, the projected drive  208  of a medical device can be depicted on the display  220  and can show the healthcare provider the projected path  208  that the medical device  242  will take if it is driven along its central axis. Although the trajectory of only one medical device is displayed, it will be understood that the trajectory of multiple medical devices can be determined and displayed simultaneously on screen  220 , as described in greater detail in the &#39;274 Application. 
     In some embodiments, to implement the trajectory indicators  208 , the image guidance system can draw a number of rings about the axis of the medical device shaft, extrapolated beyond its tip, as depicted in  FIG. 4 . A healthcare provider can view and manipulate the emplacement of the medical device  242  and its expected drive projection (via its displayed projected trajectory) before it enters the patients tissue. In some embodiments, this is accomplished by the doctor positioning the virtual rings in the drive projection such that they are co-incident (or pass through) the ultrasound representation of a target, such as a tumor that the doctor has spotted in the ultrasound. This can allow the healthcare provider to verify that the medical device  242  is properly aimed at the target and can drive the medical device  242  forward into the tissue such that it reaches its desired target or destination. For example, if the doctor identifies a tumor  212  in the ultrasound image, she can align the ablation needle  242  such that the drive projection rings on display  220  intersect or otherwise indicate that the medical device, if driven straight, will reach the tumor  212 . 
     The rings can, in some embodiments, be spaced at regular (e.g., 0.5, 1, or 2 cm) intervals to provide the healthcare provider with visual or guidance cues regarding the distance from the medical device tip to the targeted anatomy. In some embodiments, the spacing of the rings can indicate other aspects of the data, such as the drive speed of the medical device, the density of the tissue, the distance to a landmark, such as the ultrasound data, or any other appropriate guidance data or property. In some embodiments, the rings or other trajectory indicators can extend beyond the medical device tip, by a distance equal to the length of the medical device-shaft. This way, the user knows if the medical device is long enough to reach the target--even before the tip enters the patient. That is, in some embodiments, if the rings do not reach the target with the tip still outside the body, then the tip will not reach the target even when the entire length shaft is inserted into the body. 
     Other display markers can be used to show trajectory, such as a dashed, dotted, or solid line, transparent medical device shaft, point cloud, wire frame, etc. In some embodiments, three-dimensional rings can be used and provide depth cues and obscure little of the ultrasound image. Virtual rings or other virtual markers can be displayed semi-transparently, so that they obscure less of the ultrasound image than an opaque marker would. 
     Other prediction information can also be displayed as image guidance cues. For example, if a scalpel is being tracked by the image guidance system, then a cutting plane corresponding to the scalpel can be displayed (not pictured). Such a cutting plan can be coplanar with the blade of the scalpel and can project from the blade of the scalpel. For example, the projected cutting plane can show where the scalpel would cut if the doctor were to advance the scalpel. Similar prediction information can be estimable or determinable for cauterizers, lasers, and numerous other surgical instruments. 
     Furthermore, the data from two or more devices can be combined and displayed based on their relative emplacements or poses. For example, the system  100  can determine the emplacement of an image plane based on the emplacement information of the ultrasound probe  222 . Further, the rendered ultrasound image  204  can be displayed on the image plane with respect to the virtual medical device  202  on the display  220  in a manner that estimates the relative emplacements or poses of an ultrasound probe  222  and the medical device  242 . As illustrated in  FIG. 2 , the image guidance cues associated with the virtual medical device  202 , including the affected region indicator  206  and trajectory indicators  208 , are shown spatially located with the rendered ultrasound image  204  on display  220 . 
     In addition, the display  220  can include another image guidance cue in the form of an intersection indicator  210  that indicates where the virtual ablation medical device  202  (and/or its trajectory) intersects the ultrasound image  204 . In some embodiments, the intersection indicator  210  can be displayed before the medical device is inserted, thereby allowing the healthcare provider to see where the medical device will intersect the image, or imaged area. 
     In the illustrated embodiment, a tumor  212  appears in the ultrasound image, or rendered ultrasound image  204 , and the virtual ablation needle  202  is shown driven through the tumor  212 . As will be described in greater detail below, the displayed affected region (or affected region indicator)  206  can indicate what region or volume would be affected when the medical device  242  is operated. In the illustrated embodiment, the displayed affected region  206  can estimate where ablation would occur if the tissue were ablated at that time. As can be seen, in the illustrated embodiment, the displayed affected region  206  appears to cover the tumor displayed in the ultrasound image. 
     Various embodiments can include any combinations of the graphics described above and/or other graphics or image guidance cues. For example, in some embodiments, data related to a single surgical instrument (such as an ablation needle, ultrasound probe, etc.) can be presented in more than one manner on a single display. Consider an embodiment in which device  242  is an ablation needle and device  222  is an ultrasound transducer. As mentioned previously, as the medical devices are displayed in a virtual 3D space, with the screen  220  acting as a window into the virtual 3D space, if a healthcare provider orients ultrasound transducer  222  such that it is perpendicular to the point-of-view or point-of-view location (e.g., perpendicular to the screen), the perspective view of the ultrasound image  204  would show only the edge and the contents of the ultrasound image  204  would not be visible. In some embodiments, the image guidance system can track the healthcare provider&#39;s head using an emplacement sensor and/or a position sensing unit. In some embodiments, such as, when the head of a user is tracked, the healthcare provider can then move her head to the side, so that she sees the ultrasound image from a different point of view location. 
     In some embodiments, the image guidance system can constantly display an additional 2D view  205  of the ultrasound image, simultaneous to the 3D depiction  204 , so that the ultrasound image is always visible, regardless of the emplacement in which the healthcare provider holds the transducer  222 . The 2D view  205  of the ultrasound data can be similar to what a healthcare provider is accustomed to seeing with traditional ultrasound displays. This can be useful to provide the healthcare provider with imaging to which she is accustomed and allows a healthcare provider to see the ultrasound data regardless of the then-current emplacement of the ultrasound probe with respect to the user. 
     In some embodiments, the 2D view  205  of an ultrasound image is depicted in the upper right corner of the monitor (though it can be placed in any location). In some embodiments, the guidance system can automatically (and continually) choose a corner in which to render the 2D view  205  of the ultrasound image, based on the 3D position of the surgical instruments in the rendered scene. For example, in  FIG. 2 , ablation needle  242  can be held in the healthcare provider&#39;s left hand and the medical device shaft is to the left of the 3D view of the ultrasound image slice, so that the 2D view  202  of the ultrasound image in the upper right corner of display  220  does not cover any of the 3D features of the medical device (or vice-versa). If the medical device were held in the healthcare provider&#39;s right hand, the virtual medical device shaft would appear on the right side. To prevent the 2D view  205  in the corner of display  220  from covering the medical device shaft, the system can automatically move it to a corner that would not otherwise be occupied by graphics or data. 
     In some embodiments, the system attempts to avoid having the 2D view  205  of the ultrasound image quickly moving among corners of the display in order to avoid overlapping with graphics and data in the display. For example, a function f can be used to determine which corner is most suitable for the 2D ultrasound image to be drawn in. The inputs to f can include the locations, in the screen coordinate system, of the displayed medical device tip, the corners of the 3D view of the ultrasound image, etc. In some embodiments, f&#39;s output for any given point in time is independent of f&#39;s output in the previous frames, which can cause the ultrasound image to move among corners of the display rapidly. In some embodiments, the image guidance system will filter f&#39;s output over time. For example, the output of a filter g, for any given frame, could be the corner, which has been output by f the most number of times over the last n frames, possibly weighting the most recent values for f most heavily. The output of the filter g can be used to determine in which corner of display  220  to display the 2D ultrasound image and the temporal filtering provided by g can allow the 2D view  205  of the ultrasound image display to move more smoothly among the corners of the display  220 . 
     In some embodiments, other appropriate virtual information and/or image guidance cues can be overlaid on the 2D view  205  of the ultrasound image as well as the 3D view  204 . Examples include: orientation indicator  214 , an indication of the distance between the medical device&#39;s tip and the point in the plane of the ultrasound image that is closest to the medical device tip; the cross section or outline of the ablation volume that intersects with the ultrasound slice; and/or the intersection point, box, outline, etc. between the medical device&#39;s axis and the ultrasound image plane. 
     Furthermore, it will be understood that other image guidance cues can be generated and displayed on the display as described in greater detail in the &#39;274 Application, previously incorporated herein by reference. For example, the system  100  can generate and/or display graphical indicators that help indicate the spatial relationship between a medical device and an ultrasound image plane (e.g., graphical image plane indicators) or other plane (e.g., graphical plane indicators), indicators to indicate the relative positions of the medical device(s) and ultrasound image, features of interest, annotations, foundational plane indicators, foundational plane intersection indicators, other graphical indicators, approximate medical device location indicators, etc. As described in greater detail above and in the &#39;274 Application, the various image guidance cues can be generated based at least in part on the emplacement information of the medical devices used with the system  100 . 
     Depicting Affected Region and Other Information 
     Embodiments of the system can include image guidance cues as part of the image guidance data to depict information related to the region or regions that will be affected by the use of surgical instruments. For example, in some embodiments, an image guidance cue displayed by the image guidance system can include affected region information. The illustrated embodiment of  FIG. 2  shows a virtual ablation needle  202 , which has a darkened portion  203  that indicates where the radio frequency or microwave energy for ablation will be emitted, and a displayed affected region  206  showing the volume that will be, or is being, ablated. 
     In some embodiments, the system can use the operating parameters of the medical device  242  and/or measured parameters to determine the affected region (and display the displayed affected region  206 ). For example, in some cases, the affected region&#39;s approximate size (e.g., girth and length) can be either specified by the healthcare provider, or automatically computed by the guidance system based on or more operating parameters, such as, but not limited to, the medical device make and model, power and duration settings of the medical device (e.g., microwave or radio frequency generator for ablation needles, etc.), and the like. Similarly, the system can use measured parameters to determine the affected region, such as, but not limited to, measured or estimated temperature, impedance of surrounding tissue. In some embodiments, the measured parameters can be received in real-time as real-time data. In either case, the system can use one or more a formulas, a look-up-tables, fixed or default values, or any other appropriate available information, etc. to determine the affected region. 
     In addition, the system can determine affected regions prior to operating the medical device and/or during operation of the medical device. For example, prior to operating the medical device, the system can determine one or more predicted affected regions and/or during operation of the medical device, the system can determine one or more dynamic affected regions. In some embodiments, the predicted affected regions can be static during operation of the medical device and the dynamic affected regions can change over time. In certain embodiments, the system may rely more on operating parameters of the medical device to determine the predicted affected regions and measured parameters to determine the dynamic affected regions. However, it will be understood that operating parameters and/or measured parameters can be used to determine the predicted affected regions and/or the dynamic affected regions 
     In some circumstances, the operating parameters, measured parameters, formulas, a look-up-tables, fixed or default values, or other information used to determine the affected regions may include some amount of error or variance. The variance may be due to uncertainty regarding the tissue that will be presented for ablation, a manufacturers indication that impedance, temperature, power, etc., can vary between tissue and/or medical devices, etc. 
     As such, it can be difficult to determine the affected region with certainty. Thus, the operating parameters or other data can include one or more variance parameters indicating the amount of variance that a healthcare provider can expect when using a particular medical device. The variance parameter may account for all possible outcomes or a significant portion of possible outcomes (non-limiting examples: 95% or 99%). For example, the variance parameter can indicate that a medical device operates within a certain range, or that a healthcare provider can expect a certain volume to be affected with a particular standard deviation and/or +/− some percent. For example, the variance parameter may indicate that, when operating for a particular amount of time, an ablation needle will ablate a certain range of tissue, or that a certain amount of tissue will be ablated with a particular standard deviation and/or +/− some percent. 
     Accordingly, in such scenarios, the system can determine multiple affected regions based at least in part on the variance parameter. For example, the system can determine two affected regions using the extrema of the variance parameter. In some cases, such as when the variance parameter includes a lower threshold and a higher threshold, the system can determine two affected regions using the lower threshold and the higher threshold, respectively. The affected regions can be predicted affected regions and/or dynamic affected regions depending on when and how the system determines them. In some cases, a third affected regions can be determined. The third affected region can be determined using a third point in the range, such as the midpoint, average, or other point. 
     The system can also determine the emplacement of the affected region. In some cases, the emplacement of the affected region can be based at least in part on the emplacement of some or all of the corresponding medical device (or virtual medical device) , such as medical device  242  in  FIG. 2 . For example, the system can receive emplacement data from one or more emplacement sensors associated with the medical device  242  (non-limiting examples: coupled to or integrated with the medical device  242 , within an optical path of the medical device, etc.). The system can use the emplacement data to determine the emplacement of the tracked medical device and/or the emplacement of the virtual medical device  202  corresponding to the medical device  242 . In some instances, the system can determine the emplacement of the medical device  242  and/or virtual medical device  202  with respect to a point-of-view location. 
     As yet another example, if the medical device is an ablation needle and the affected region is an ablation volume, the emplacement of the ablation volume can be based at least in part on the emplacement of the ablation needle (or its rendered version) or at least a portion of it, such as the location on the ablation needle where the ablation energy will be emitted. Specifically, in some embodiments, the affected region can be centered at a location on the medical device, such as the location on the medical device that affects the surrounding tissue (non-limiting examples: microwave emitter, laser source output, etc.). Similarly, if multiple medical devices are used, the posed can be based at least in part on the emplacement of the medical devices. 
     The system can display the affected region in a variety of ways. Furthermore, although the illustrated embodiment of  FIG. 2  includes only one displayed affected region  206 , it will be understood that one or more affected regions can be displayed corresponding to each medical device  242  that is displayed on the screen  220  and/or multiple affected regions can be displayed corresponding to a single medical device  242 . In some embodiments, the system can display a perspective view of the affected region and/or non-perspective view, such as by displaying the affected region on or with the ultrasound image displayed in the 2D view. Some or all of the affected regions can be displayed as desired. In some embodiments, the portion of the affected region that is displayed can be referred to as the displayed affected region and/or the surface display region. 
     For some medical devices, the expected volume of ablated tissue is neither spherical nor centered at the tip of the medical device. Accordingly, in such embodiments, the affected regions can match expected volumes. For example, a Covidien surgical microwave medical device has an ellipsoidal ablation volume; a Covidien Evident transcutaneous microwave medical device has a teardrop-like ablation volume; RFA Medical&#39;s bipolar ablation system uses two medical devices simultaneously, where each medical device has paddles that deploy after the medical device is inserted inside the tissue (which one can equate to a canoe&#39;s oar). In some embodiments, the affected region for such a medical device corresponds to a volume that lies directly between the paddles of the two medical devices. 
     Although the illustrated embodiment of  FIG. 2  refers to the affected region as an ablation volume, it will be understood that the affected region can correspond to a variety of medical procedures. For example, if a cauterizer is tracked as part of an image guidance system, then the affected region can correspond to a cauterization volume. If a laser is tracked as part of the image guidance system, then the affected region can correspond to the projected laser path. Similarly, the affected region can correspond to a biopsy volume, an electroporated volume, cryoablation volume, laser ablation volume, high-frequency focused ultrasound ablation (HIFU) volume, external beam radiation therapy volume, and drilling volume (where the display volume corresponds to the region of bone and other tissue that the manually operated, or computer-controlled drill would remove), depending on the type of medical instrument being used. 
     Example Displayed Affected Regions 
     As non-limiting examples and with reference to  FIGS. 3A-3J, 4A-4C, and 5A-5C , the system can display the affected regions as a transparent volume, a wireframe volume (as depicted in  FIG. 2 ), a volume with varying opacity, a point cloud of various densities, a surface, an outline, or any portion thereof. As mentioned above, the affected regions can correspond to predicted affected regions and/or dynamic affected regions, as desired. 
     When displaying a portion of a volume, the system can display the portions of the volume that are located in front of the image slice with respect to the point-of-view location (or display them differently than portions that are behind the image slice), alternating bands or tiles of the affected region, portions of the affected region that are co-located with or intersect the medical device and/or the image slice. In addition, when multiple affected regions are determined, the system can display them in any combination as described above. Further, in some embodiments, such as when the system determines a second affected region that includes a first affected region, the displayed affected region can include the portions of the second affected region that are unique second affected region with respect to the first affected region only, or in combination with other portions. In certain embodiments, such as when the system determines that portions of a second affected region and a first affected region overlap, the system can display the overlapping portions only, or in combination with other portions. 
     Furthermore, the system can display the affected regions and other displayed features differently. For example, in some embodiments, the system can vary the characteristics of the affected regions (non-limiting examples: portions closer to the outline or edge of the affected regions can be more/less opaque, bright or focused, distal portions of the affected regions can be more/less opaque, bright or focused). Similarly, the system can vary the characteristics of the other displayed features. In some embodiments, the system can use different display settings for different portions of an image slice. For example, the system can display portions of the image slice within a first affected region using a first setting, portions of the image slice within a second affected region using a second setting, and portions of the image slice outside the first and second affected regions using a third setting. The different settings can correspond to different opacity levels, brightness levels, contrast levels, and/or focus levels, etc. In some embodiments, portions of the image slice outside the first and second affected regions can be darkened, blurred, or otherwise adjusted to provide the healthcare provider with additional insight regarding the portions of the image slice that are within the affected region(s). 
       FIGS. 3A-3J  are diagrams illustrating various non-limiting embodiments for displaying a perspective view of at least a portion of the affected regions as a volume.  FIG. 3A  illustrates an embodiment in which two affected regions are displayed as two transparent volumes  302 ,  304  and/or outlines along with a virtual medical device  301 .  FIG. 3B  illustrates an embodiment in which two affected regions are displayed as two volumes  306 ,  308  with varying opacity (or as semi-transparent). In the illustrated embodiment, the volumes  306 ,  308 , are more opaque near the edges, however, it will be understood that the opacity can be varied throughout the volumes  306 ,  308  as desired. 
       FIG. 3C  illustrates an embodiment in which two affected regions are displayed as two volumes  310 ,  312  with a surface texture.  FIG. 3D  illustrates an embodiment in which a portion of the affected region that is located between the image slice  314  and the point-of-view location (or in front of the image slice  314 ) is displayed as a volume  316 . It will be understood that the portion of the affected region that is located between the image slice  314  and the point-of-view location can be displayed differently from portions of the affected region that is located distally from the point-of-view location with respect to the image slice  314 . For example, the different portions can be displayed with different colors, brightness, sharpness, etc. In some cases, the portions of the affected region located distally from the point-of-view location with respect to the image slice  314  can be displayed with lighter or more faded colors, etc. 
       FIG. 3E  illustrates an embodiment in which portions of a second affected region are displayed. The portions displayed correspond to the portions of the second affected region that are unique to the second affected region with respect to the first affected region. In the illustrated embodiment, the portions are displayed as spikes  318 . However, it will be understood that any shape or design can be used as desired. In some embodiments, the spikes  318  can be a predefined length and/or have marking as predefined lengths, such as 1 cm. As such, user can use the spikes to determine distances of object displayed on the screen. Although not illustrated in  FIG. 3E , it will be understood that the opacity of the spikes can vary  318  as desired. In some embodiments, such as when the second affected region is a predicted affected region, as a dynamic affected region grows, the system can cause the spikes  318  to become transparent, or otherwise adjust a display setting, based at least in part on the location of the dynamic affected region with respect to the spikes  318 .  FIG. 3F  illustrates an embodiment in which the embodiments from  FIGS. 3B and 3E  are combined. As mentioned previously, any combination of the described embodiments can be used as desired. 
       FIG. 3G  illustrates embodiments in which portions of three affected regions are displayed as outlines  320   a,    320   b,    322   a,    322   b,    324   a,    324   b.  In some embodiments, outlines  320   a,    320   b  correspond to vertical and horizontal edges, respectively, of a first affected region, outlines  322   a,    322   b  correspond to vertical and horizontal edges, respectively, of a second affected region, and outlines  324   a ,  324   b  correspond to vertical and horizontal edges, respectively, of a third affected region.  FIG. 3G  also illustrates embodiments in which the one or more outlines  320   a,    320   b,    322   a,    322   b,    324   a,    324   c  are associated with a particular affected region, such as portions of a second affected region that are unique to it with respect to a first affected region. 
       FIG. 3H  illustrates an embodiment in which the two affected regions are displayed as two volumes  326 ,  328 , in which the portions of the second affected region that are unique to the second affected region with respect to the first affected region are displayed differently (non-limiting examples: varying opacity, color, brightness, focus, etc.). 
       FIG. 3I  illustrates embodiments in which portions of an affected region are displayed using horizontal bands  330  with alternating display settings (e.g., transparency, brightness, etc.). It will be understood that bands with any orientation can be used. Bands with higher transparency levels can enable a healthcare provider to see into the affected region. In some embodiments, the width and/or the arc length of each band can be equal, and a top portion  332  and a bottom portion  334  can have a variable corresponding width/arc length. As such, user can use the bands to determine distances of object displayed on the screen. The variable width/arc length can be determined such that the bands  330  have an equal width/arc length. 
       FIG. 3J  illustrates an embodiment in which portions of an affected region are displayed using tiles  336  having alternating display settings (e.g., transparency, brightness, etc.). In some embodiments, each tile  336  can be displayed with a different display level. In certain embodiments, every other tile can be displayed with the same display level. Tiles with higher transparency levels can enable a healthcare provider to see into the affected region. In some embodiments, horizontal and/or vertical lengths and/or the arc length of each tile can be equal, and a top portion and a bottom portion can have a variable corresponding length. The variable length can be determined such that the tiles  336  have an equal length. 
     Surface Display Regions 
       FIGS. 4A-4C, and 5A-5C  are diagrams showing various embodiments for displaying at least a portion of the affected regions that intersect with or are co-located or level with at least a portion of a medical display object (non-limiting examples: the image slice  302  ( FIGS. 4A-4C ) or the virtual medical device ( FIGS. 5A and 5B )), which may also be referred to herein as surface display regions. 
     The surface display regions can correspond to predicted affected regions and/or dynamic affected regions, as desired. Accordingly, if the first and/or second affected regions are dynamic affected regions, the associated surface display regions can move, or grow, during operation of the medical device associated with the virtual medical device  401 ,  501 . 
     In addition, the surface display regions can correspond to affected regions that are co-located with the medical display object or only portions thereof, or the medical display object&#39;s trajectory. Accordingly, in some embodiments, the surface display region can be displayed as a volume, area, or line depending on which portions of the affected region and medical display object are used to determine the surface display region. 
     In some embodiments, to determine whether a portion of the affected region and a portion of the medical display object are co-located or level, the system  100  can compare the coordinates of the portion of the affected region with the portion of the medical display object. If the coordinates (e.g., the x, y, z coordinates) match (e.g., are equal) or satisfy a distance threshold, the system can determine that the portion of the medical display object and the portion of the affected region are co-located. In certain embodiments, the system  100  can determine that the portion of the affected region and the portion of the medical display object are co-located if the portion of the affected region and the portion of the medical display object can be mapped to the same pixel in a video or image output data buffer. 
     The distance threshold can be a predefined distance, such as one or more bits, one or more pixels, etc. In some embodiments, the distance threshold can be based at least in part on whether the distance between the coordinates is perceptible to a user, which may be based at least in part on the size of the display, the size of the display relative to the image and/or imaged area, and/or the distance between the point-of-view location and the display, etc. For example, in some cases, the distance threshold can be smaller for larger displays (or larger display:image ratios) and larger for smaller displays (or smaller display:image ratios), or vice versa. In certain cases, the distance threshold can be larger for larger distances between the point-of-view location and the display and smaller for smaller distances between the point-of-view location and the display, or vice versa. In certain embodiments, the distance threshold can be different for each coordinate. 
     In certain embodiments, the system  100  can perform the comparison for each location of the medical display objects and/or each location of the affected regions. In some cases, the system can determine that the portion of the medical display object and the portion of the affected region are co-located if the portion of the medical display object and the portion of the affected region are level and have the same depth. 
     Any coordinate system can be used to compare the coordinates of the portion of the affected region with the medical display object and/or to determine whether the portion of the affected region is co-located with the medical display object. For example, the coordinate system of the display and/or the coordinate system of device in the system  100  that is used to determine the emplacement of the medical devices can be used, as desired. 
     In some embodiments, the coordinate system of the display is used. The coordinate system of the display can be any emplacement as desired. In certain embodiments, the coordinates of the display are that the x-axis is the width of the display, the y-axis is the height of the display, and the z-axis is the depth (e.g., into and out of) the display. In such embodiments, the system  100  can determine that the portion of the affected region satisfies the location threshold and/or is level with the medical display object, based at least in part on the x and y coordinates of the affected region and the x and y coordinates of the medical display object. For example, if the x and y coordinates of the affected region and the x and y coordinates of the medical display object match (or satisfy a distance threshold); the system  100  can determine that the portion of the affected region satisfies the location threshold. 
     Although reference is made to the x and y coordinates, it will be understood that the coordinates used to determine whether the portion of the affected region satisfies the location threshold and/or is co-located with the medical display object can be based at least in part on the coordinate system used. For example, in some embodiments, the coordinate system used can include the x-axis as the depth (e.g., forward/backward), the y-axis as lateral movement (e.g., side-to-side), and the z-axis as elevation (e.g., up/down). In such embodiments, the system  100  can determine that portion of the affected region satisfies the location threshold if the y and z coordinates of the affected region match (or satisfy a distance threshold) the y and z coordinates of the medical display object. 
     In some embodiments, for each location on the display, the system can query whether a portion of the medical display object and/or a portion of the affected region have been (or will be) mapped to that location. If the system  100  determines that a portion of the medical display object and a portion of the affected region have been (or will be) mapped to that location, the system  100  can determine that the portion of the medical display object and the portion of the affected region are co-located. 
     In certain embodiments, the system  100  can determine that the portion of the affected region satisfies the location threshold, intersects, and/or is co-located with the medical display object if the portion of the affected region and the medical display object (or portion of the image corresponding to the medical display object) are co-located when mapped to a 2D plane. In some embodiments, the 2D plane can be based at least in part on the point-of-view location. For example, the 2D plane can be orthogonal to the point-of-view location. In certain embodiments, the system  100  can determine that the portion of the affected region satisfies the location threshold (or corresponding virtual affected region) if the portion of the affected region overlaps with the medical display object (or portion of the image corresponding to the medical display object) in a virtual image (e.g., one is directly in front of or behind the other in the virtual image). In certain embodiments, the system  100  can determine that the portion of the affected region satisfies the location threshold if the portion of the affected region and the medical display object (or portion of the image corresponding to the medical display object) map to the same location on a display, such as the same pixel or same array of pixels. 
     With continued reference to  FIGS. 4A-4C , various embodiments of surface display regions are shown. It will be understood that the embodiments illustrated in  FIGS. 4A-4C  are non-limiting in nature. Furthermore, any portion of any of the embodiments described above with reference to  FIGS. 3A-3J  can be displayed in conjunction with any portion of the embodiments described below with reference to  FIGS. 4A-4C . 
       FIG. 4A  illustrates various embodiments including embodiments showing two surface display regions as lines  402 ,  404 . The line  402  can correspond to an outline of a first affected region that is co-located with at least a portion of a virtual medical device (image slice  406 ) and the line  404  can correspond to an outline of a second affected region that is co-located at least a portion of the image slice  406 . In some embodiments, the area between the lines  402 ,  404  can be displayed differently (non-limiting examples: varying opacity, color, brightness, focus, etc.).  FIG. 4A  can also illustrate embodiments showing a surface display region displayed as area  405 . The area  405  can correspond to portions of a second affected region that are unique to it with respect to a first affected region and that are co-located with at least a portion of the image slice  406 . In certain embodiments, the portions of the area  405  can be displayed differently (non-limiting examples: varying opacity, color, brightness, focus, etc.).  FIG. 5A  is similar to  FIG. 4A  except that the medical display object is the virtual medical device  501 . Thus, lines  502 ,  504  correspond to lines  402 ,  404 , respectively, and area  505  corresponds to area  405 . In some embodiments lines  502 ,  505 , and/or area  505  can correspond to portions of a second affected region that are co-located with at least a portion of the virtual medical device  501  and/or its trajectory. 
       FIG. 4B  illustrates various embodiments showing multiple solid lines  408 ,  410  and dashed lines  412 ,  414 , which can form part of one or more surface display regions. For example, lines  408 ,  410  can correspond different portions of a first affected region (and form part of a first surface display region) and lines  412 ,  414  can correspond to different portions of a second affected region (and form part of a surface display region). In some embodiments, line  408  forms part of a first surface display region and lines  410 ,  412 ,  414  form part of a second surface display region, such as portions of the second affected region that are unique to it with respect to the first affected region. In certain embodiments, lines  408 ,  410 ,  412 ,  414  form part of four surface display regions.  FIG. 5A  is similar to  FIG. 4A  except that the medical display object is the virtual medical device  501 . Thus, lines  508 ,  510 ,  512 ,  514  correspond to lines  408 ,  410 ,  412 ,  414 , respectively, and area  505  corresponds to area  405 . 
       FIG. 4C  illustrates an embodiment in which an additional surface display region is displayed with the surface display regions illustrated in  FIG. 4B . In an embodiment, line  408  forms part of a first surface display region that corresponds to a first predicted affected region and lines  410 ,  412 ,  414  form part of a second surface display region that corresponds to a second predicted affected region. Indicators  416  form part of a third surface display region, which corresponds to a dynamic affected region. As such, during operation of the medical device that corresponds to the virtual medical device  401 , lines  408 ,  410 ,  412 , and  414  can remain static, while indicators  416  move outward. In this manner, a healthcare provider can determine at what point to terminate operation of the medical device. Although a corresponding  FIG. 5  is not provided, it will be understood that the medical display object can correspond to any object displayed by a display. 
     It will be understood that any of the aforementioned embodiments from  FIGS. 3A-3J, 4A-4C, 5A, and 5B  can be combined as desired. For example,  FIG. 5C  is a diagram illustrating an embodiment in which the embodiments described above with reference to  FIGS. 3D, 3G, 4C, and 5B  are combined. 
       FIG. 6  is a flow diagram illustrative of an embodiment of a routine  600  implemented by the system  100  to display at least a portion of an affected region, or displayed affected region. One skilled in the relevant art will appreciate that the elements outlined for routine  600  can be implemented by one or more computing devices/components that are associated with the system  100 , such as the position sensing unit  140 , the image guidance unit  130 , surgical system  149 , and/or imaging unit  150 . Accordingly, routine  600  has been logically associated as being generally performed by the system  100 . However, the following illustrative embodiment should not be construed as limiting. Furthermore, it will be understood that the various blocks described herein with reference to  FIG. 6  can be implemented in a variety of orders. For example, the system may implement some blocks concurrently or change the order, as desired. 
     At block  602 , the system  100  receives operating parameters of a medical device. As described in greater detail above, the operating parameters can include information regarding make and model, power and duration settings of the medical device, and/or variance parameters, etc. The operating parameters can be stored in a non-transitory, computer-readable medium associated with the system  100  and/or can be stored in the medical device. 
     At block  604 , the system  100  determines a first affected region. As described previously, affected regions can correspond to predicted affected regions and/or a dynamic affected regions. In some embodiments, the system determines the first affected region based at least in part on the operating parameters and/or measured parameters. In certain embodiments, the system  100  determines the first affected region based at least in part on a variance parameter of the medical device. 
     At block  606 , the system  100  causes one or more displays to display at least a portion of the first affected region, or first displayed affected region. As described previously, the first displayed affected region can be displayed in a 2D view or 3D view and/or as a perspective view. 
     In addition, as described in greater detail above, the displayed affected region can be displayed as a volume, area, and/or line. The displayed affected region can be wire-framed, transparent, semi-transparent, have varied opacity, brightness, and/or focus, include alternating bands/tiles, be textured, include solid or dashed lines, include spikes, etc. In certain embodiments, the at least a portion of the first affected region corresponds to portions of the first affected region that are unique to it, with respect to other affected regions. In some embodiments, the displayed affected region corresponds to at least a portion of the first affected region that is co-located with at least a portion of a medical display object (non-limiting examples: a virtual medical device, image slice, etc.) or its trajectory, also referred to as the surface display region. 
     It will be understood that fewer, more, or different blocks can be used as part of the routine  600 . For example, any combination of blocks  608 ,  610 ,  612 , and  614  can be included as part of routine  600 . 
     At block  608 , the system  100  determines a second affected region. The second affected region can be determined in a manner similar to the first affected region. As described in greater detail above, in some embodiments, the variance parameter can be used to determine the first and second affected regions. For example, a first variance threshold can be used to determine the first affected region and a second variance threshold can be used to determine the second affected region. In certain cases, the first variance threshold can be less than the second variance threshold. In such embodiments, the second affected region can be larger than, and in some cases include, the first affected region. 
     At block  610 , the system  100  causes one or more displays to display at least a portion of the second affected region, or second displayed affected region. The system  100  can cause the one or more displays to display the second displayed affected region similar to the first displayed affected region. In some embodiments, the second displayed affected region can be displayed differently, such as by using a different color, transparency level, focus setting, shape, texture, etc. Furthermore, in some embodiments, the system can omit causing the display of the first displayed affected region in favor of the second displayed affected region. In such embodiments, the second displayed affected region can, in some instances, correspond to the portions of the second affected region that are unique to the second affected region, with respect to the first affected region. 
     In some instances the first affected region can be a predicted affected region and the second affected region can be a dynamic affected region. As such, in certain embodiments, during operation of the medical device, the second displayed affected region can change and/or grow with respect to the first displayed affected region. 
     At block  612 , the system  100  determines a third affected region. For example, in some embodiments, the first and second affected regions can be first and second predicted affected regions and the third affected region can be a dynamic affected region. However, in certain embodiments the three affected regions can be dynamic affected regions, predicted affected regions, or any combination thereof. 
     At block  614 , the system  100  causes one or more displays to display at least a portion of the third affected region, or third displayed affected region. The system  100  can cause the one or more displays to display the third displayed affected region similar to the first and second displayed affected regions. In some embodiments, the third displayed affected region can be displayed differently, such as by using a different color, transparency level, focus setting, shape, texture, etc. In embodiments, where the third affected region is a dynamic affected region and the first and second affected regions are predicted affected regions, the third displayed affected region can move with respect to the first and second displayed affected regions. 
     With continued reference to  FIG. 6 , it will be understood that fewer or more blocks can be included. For example, as described in greater detail above, the system  100  can receive emplacement data from one or more sensors corresponding to one or more medical devices, determine a emplacement of the medical devices and/or corresponding virtual medical devices (as a non-limiting example, the emplacement can be determined based at least in part on a point-of-view location), cause one or more displays to display the virtual medical devices and/or perspective views thereof, determine emplacement of the affected regions with respect to the virtual medical devices, determine emplacement of and display an image slice, alter the display of the image slice, display the medical display objects in a 2D view, a 3D view, and/or a perspective view, etc. 
       FIG. 7  is a flow diagram illustrative of an embodiment of a routine  700  implemented by the system  100  to display at least a portion of multiple affected regions, or multiple displayed affected regions. One skilled in the relevant art will appreciate that the elements outlined for routine  700  can be implemented by one or more computing devices/components that are associated with the system  100 , such as the position sensing unit  140 , the image guidance unit  130 , surgical system  149 , and/or imaging unit  150 . Accordingly, routine  700  has been logically associated as being generally performed by the system  100 . However, the following illustrative embodiment should not be construed as limiting. Furthermore, it will be understood that the various blocks described herein with reference to  FIG. 7  can be implemented in a variety of orders. For example, the system may implement some blocks concurrently or change the order, as desired. 
     At block  702 , the system  100  determines the emplacement of a virtual medical device. In some embodiments, as described above, the system  100  can determine the emplacement of the virtual medical device based at least in part on emplacement data corresponding to a medical device, such as medical device  242 . As described previously, the emplacement data can be received from one or more emplacement sensors associated with the medical device. 
     At block  704 , the system  100  obtains operating parameters of the medical device, as described in greater detail above with reference to block  602  of  FIG. 6 . At block  706 , the system  100  determines a first affected region. In some embodiments, the system  100  can determine the first affected region similar to the determination of the first affected region referenced above with respect to block  604  of  FIG. 6 . At block  708 , the system  100  determines a second affected region. In some embodiments, the system  100  can determine the second affected region similar to the determination of the second affected region referenced above with respect to block  608  of  FIG. 6 . As described in greater detail above the first and second affected regions can be predicted affected regions and/or dynamic affected regions, as desired. 
     At block  710 , the system  100  can determine the emplacement of the first and second affected regions. At block  712 , the system  100  can cause one or more displays to display at least a portion of the virtual medical device, at least a portion of the first affected region (second displayed affected region), and at least a portion of the second affected region (second displayed affected region). As described previously, the displayed affected regions can, in some embodiments, correspond to surface display regions. In some embodiments, the system  100  can cause the one or more displays to display at least a portion of the first and second affected regions similar to blocks  606  and  610  of  FIG. 6 , described previously. As described above, the first and second displayed affected regions can be displayed in a variety of ways. 
     It will be understood that fewer, more, or different blocks can be used as part of the routine  700 . For example, any combination of blocks  714 ,  716 ,  718 , and  720  can be included as part of routine  700 . 
     At block  714 , the system  100  can determine a third affected region, and at block  716 , the system  100  can cause the one or more displays to display at least a portion of the third affected region. In some embodiments, the system  100  can determine the third affected region and display a third displayed affected region similar to the first and second displayed affected regions as described in greater detail above with reference to blocks  612  and  616  of  FIG. 6 . In certain embodiments, the third displayed affected region can be a surface display region. 
     At block  718 , the system  100  can determine an emplacement of an image slice, and at block  720 , the system  100  can cause the one or more displays to display at least a portion of the image slice and/or perspective view thereof, as described in greater detail above. 
     With continued reference to  FIG. 7 , it will be understood that fewer or more blocks can be included. For example, as described in greater detail above, the system  100  can receive emplacement data from one or more sensors associated with one or more medical devices, display additional displayed affected regions, alter the display of the image slice, display image guidance cues, display the medical display objects in a 2D view, a 3D view, and/or a perspective view, etc. 
     Terminology 
     Those having skill in the art will further appreciate that the various illustrative logical blocks, modules, circuits, and process steps described in connection with the implementations disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. One skilled in the art will recognize that a portion, or a part, can comprise something less than, or equal to, a whole. For example, a portion of a collection of pixels can refer to a sub-collection of those pixels. 
     The various illustrative logical blocks, modules, and circuits described in connection with the implementations disclosed herein can be implemented or performed with a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or microcontroller. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     The steps of a method or process described in connection with the implementations disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of non-transitory computer-readable medium known in the art, as computer-executable instructions. An exemplary computer-readable storage medium is coupled to the processor such the processor can read information and/or computer-executable instructions from, and write information to, the computer-readable storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal, camera, or other device. In the alternative, the processor and the storage medium can reside as discrete components in a user terminal, camera, or other device. 
     Headings are included herein for reference and to aid in locating various sections. These headings are not intended to limit the scope of the concepts described with respect thereto. Such concepts can have applicability throughout the entire specification. 
     Conditional language such as, among others, “can,” “could,” “might” or “may,” unless specifically stated otherwise, are otherwise understood within the context as used in general to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. 
     Language such as the phrase “at least one of X, Y and Z,” and “at least one of X, Y or Z,” unless specifically stated otherwise, is understood with the context as used in general to convey that an item, term, etc. may be either X, Y or Z, or any combination thereof. Thus, such language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present or exclusively X or exclusively Y or exclusively Z. 
     Unless otherwise explicitly stated, articles such as ‘a’ or ‘an’ should generally be interpreted to include one or more described items. Accordingly, phrases such as “a device configured to” are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, “a processor configured to carry out recitations A, B and C” can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C. 
     The previous description of the disclosed implementations is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other implementations without departing from the spirit or scope of the invention. Furthermore, although described above with reference to medical devices and procedures, it will be understood that the embodiments described herein can be applied to other systems in which objects are tracked and virtual representations are displayed on a display and/or systems in which multiple objects are displayed on a display within a virtual space, such as within a virtual 3D space. Thus, the present invention is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.