MEDICAL GUIDANCE SYSTEM AND METHOD USING LOCALIZED PLANE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. application 15/727978 filed Oct. 9, 2017, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present disclosure relates to medical devices including medical guidance devices implementing a medical guidance system and method using a localized plane for planning and/or executing percutaneous interventions.

Description of Related Art

[0003] In the medical field, accurate and precise positioning of medical instruments is critical. In the case of surgical procedures such as percutaneous intervention, exact placement of needle-like medical tools and instruments can mean the difference between success and failure of procedures. To aid in the positioning and to achieve an accurate and intuitive orientation of the medical tool, it has become common practice to track a medical tool such as a needle using different guiding type methods.

[0004] International application WO2010/096419 A2 discloses a needle-guiding device that provides tracking information of a needle-like medical tool by using tracking devices on the needle-like medical tools as well as on the patient. However, the device described does not provide information about cross-sectional images on an insertion plane when the physician makes a plan of insertion before bringing the needle to the patient. Therefore, the physician experiences difficulty planning the insertion, especially when the insertion is out of the axial imaging plane of the medical imaging device.

Moreover, the device in WO2010/096419 A2 needs multiple tracking sensors in the system to accomplish the desired task. Thus, the system requires calibration for multiple tracking sensors adding an increased level of complexity in operation.

[0005] Additionally, U.S. Patent No. 9,222,996 discloses a needle positioning system with an image guide system, a needle placement manipulator and a manipulator controller. The needle placement manipulator requires two rotatable ring structures with actuators, position sensors and fiducial markers, and directs a needle holder to a target position. Here, the image guide system acquires medical images, and can compute needle location and orientation in a medical image based on markers visible in the medical images, and can send the needle location and orientation to the manipulator controller. Then, the manipulator controller translates the needle location and orientation to command the actuators to direct the needle holder. The requirement for having two structures with actuators leads to a more complicated and bigger system to achieve proper medical device placement.

[0006] U.S. Patent 6487431 discloses a radiographic apparatus and method for monitoring the path of a thrust needle. According to this patent, a biopsy needle or a drug injection needle can be inserted into a patient accurately and quickly. To that end, a needle entry point on a body surface of the patient and a target point in the patient are designated and inputted on the screen of a display monitor. A radiographic apparatus automatically displays, on the display monitor, a guideline linking the two points, intersection marks indicative of intersections of the guideline and CT images, and angles and length serving as a reference for determining a direction and depth of running the needle. This patent discloses that where the points A and B of a needle trajectory are located in different slice planes, each slice plane imaged and the trajectory intersect only at one point, and different slice planes imaged have different points of intersection with the trajectory. It is therefore necessary to compute one position of intersection after another following movement of the needle. However, when user checks an out of plane insertion with sets of the axial images, it is difficult for user to understand the flipping direction of the images against an anatomy (e.g., tumor) of a patient to visualize needle insertion direction.

SUMMARY OF THE INVENTION

[0007] The various embodiments of the present medical guidance system and method present several novel features which address one or more deficiencies of the related art. Without limiting the scope of the present embodiments, some of the novel features will be discussed briefly to apprise the public, and more especially those interested in the particular art to which the invention relates, of the nature and scope of the present disclosure. After considering this discussion, and particularly after reading the section entitled "Detailed Description of the Embodiments," one will understand how the features of the present embodiments provide the advantages described herein.

[0008] In a first embodiment, a medical guidance system includes an orientation localizer including at least one fiducial marker and having a localized plane, wherein the orientation localizer is mountable at a skin entry point on a patient, a computer configured to receive at least one medical image on the localized plane, register a position and orientation of the orientation localizer with the at least one medical image using the at least one fiducial marker, determine at least one cross sectional image based on the at least one medical image on the localized plane, and determine an insertion plane perpendicular to the localized plane, and an image display connected to the computer, wherein the image display displays the at least one cross sectional image on the localized plane and/or on the insertion plane.

[0009] In another embodiment, a medical guidance system includes an orientation localizer including at least one fiducial marker and having a localized plane, wherein the orientation localizer is mountable at a skin entry point on a patient, a computer configured to, receive at least one medical image on the localized plane, register a position and orientation of the orientation localizer with the at least one medical image using the at least one fiducial marker, wherein the position is registered by transforming local coordinates to satisfy the following equation:

war

wherein, ^£ ' is a transformation to the coordinate for guidance of a medical tool based on the coordinate in the at least one medical image, wherein, ^{F 1} * is a transformation of the coordinate of the at least one fiducial marker from the coordinate of w ^m

the medical images, wherein, ¹ is a set of position vectors of all fiducial markers on the

T ^F (βΐ. )

coordinate of the at least one medical image, wherein, ^{:Sf s} * ^■ "' is a transformation of the coordinate of a movable ring, wherein, ^E is an angular position of a rotatable ring based on the coordinate of the at least one fiducial marker, wherein, " ^* ' ' is a transformation to a coordinate for guidance of the medical tool from the coordinate of the

QMS

movable ring, wherein, ^F is an insertion angle on an insertion-plane indicator based on the coordinate of the movable ring, and determine at least one cross sectional image based on the at least one medical image on the localized plane, and determine an insertion plane perpendicular to the localized plane, and an image display connected to the computer, wherein the image display displays the at least one cross sectional image on the localized plane and/or on the insertion plane.

[ooio] In yet another embodiment, a medical guidance system includes, a guidance device configured to guide a needle-like medical tool to an intended trajectory, and a computer configured to retrieve medical images and display the intended trajectory with the medical images, wherein the guidance device includes, a base plate including a base-plate opening, and a bottom surface configured to be mounted to a patient, a movable ring that attaches to the base plate, including a movable-ring opening aligned to the base-plate opening to form a main opening providing access to the patient, a guidance part mounting on the movable ring to guide the needle-like medical tool, and a rotary encoder including, a rotary scale mounted on the movable ring, a sensor head mounted on the base plate, a sensor circuit board connected to the sensor head, and configured to compute an angular position of the rotary scale by processing sensed signals from the sensor head, fiducial markers mounted on the base plate and configured to be visible in the medical images, and a circuit box including, a memory unit having device information to define geometrical relation between coordinates of the rotary encoder and of the fiducial markers, a microcontroller connected to the memory unit and the sensor circuit board, and configured to communicate with the computer, wherein the computer calculates geometry of the fiducial markers in the medical images with the coordinate of the medical images, and wherein the computer or the microcontroller computes a coordinate of the guidance device with the coordinate of the medical images by using the device information in the memory unit and the geometry of the fiducial markers calculated by the computer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. l is a functional block diagram illustrating a medical guidance system according to an exemplary embodiment of the present disclosure.

[0012] Fig. 2A is a top view of an orientation localizer in a medical guidance device according to a first embodiment of the present disclosure.

[0013] Fig. 2B is a bottom view of an orientation localizer in a medical guidance device according to a first embodiment of the present disclosure.

[0014] Fig. 3 is a flowchart illustrating a process relating to guidance of a needle using the medical guidance system according to a first embodiment of the present disclosure.

[0015] Fig. 4 is a plan view of an orientation localizer according to a second embodiment of the present disclosure.

[0016] Fig. 5 depicts a system of a medical device guidance system according to a second exemplary embodiment of the present disclosure.

[0017] Figs. 6A & 6B show captured axial medical images according to an exemplary embodiment of the present disclosure.

[0018] Fig. 7 is a plan view of an orientation localizer of yet another embodiment of the present disclosure.

[0019] Fig. 8 is a perspective view showing an insertion plane and localized plane according to an exemplary embodiment of the present disclosure.

[0020] Fig. 9 is a functional block diagram illustrating a medical guidance system according to another embodiment of the present disclosure.

[0021] Figs. 10A and 10B are plan views of the orientation localizer according to the embodiment as described in Fig. 9 of the present disclosure.

[0022] Figs. 11A and 11B are schematic illustrations of the orientation localizer focusing on a circuit box according to additional embodiments of the present disclosure.

[0023] Fig. 12 is a flowchart illustrating a process for guidance of a needle using a medical guidance system according to an exemplary embodiment of the present disclosure.

[0024] Fig. 13 is a schematic illustration of the transformation of local coordinates in device-to-image registration according an embodiment of the present disclosure.

[0025] Fig. 14 is an extracted flowchart of Fig. 12 detailing the sub steps for device set up according an embodiment of the present disclosure. [0026] Figs. 15 and 16 show an exemplary embodiment for interactively displaying and evaluating a planned and/or an actual insertion trajectory of a needle-like instrument.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Example medical devices, methods and systems are described herein. Any example embodiment or feature described herein is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example

embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0028] Furthermore, the particular arrangements shown in the figures should not be viewed as limiting. It should be understood that other embodiments might include more or less of each element shown in a given figure. Further, some of the illustrated elements may be combined or omitted. Yet further, an example embodiment may include elements that are not illustrated in the figures.

[0029] Exemplary embodiments of the present disclosure provide for accurately guiding and inserting a medical needle into a medical patient. Pursuant to these exemplary embodiments, a medical practitioner can utilize interactive navigation indicators and cross-sectional images on an insertion plane of the medical patient to plan safe and accurate insertion trajectories before delivery of the medical needle to the medical patient.

< guidance system and orientation localizer >

[0030] According to a first embodiment, a medical guidance device comprises: an orientation localizer including at least one fiducial marker and a localized plane; a computer that receives axial medical images of a patient; and an image display connected to the computer. The orientation localizer is a ring-shaped device mounted around a skin entry point on the patient. The computer registers the position and the orientation of the orientation localizer by using the axial medical images with an anatomy of the patient and the fiducial marker(s). The computer computes a cross sectional image of the anatomy on the localized plane and an insertion plane perpendicular to the localized plane. The image display displays at least one of the cross sectional images of the anatomy on the localized plane and/or the axial image on the insertion plane.

[0031] The medical guidance device further comprises angular scales that are arrayed on the orientation localizer and indicate the angular position of the insertion plane on the localized plane. The computer computes a target angular scale

corresponding to the insertion plane displayed on the image display, and provides feedback information (the target angular scale) to an operator.

[0032] In one embodiment, the orientation localizer includes a fixed base body with the fiducial markers and a rotatable body with an insertion-plane indicator and a rotary encoder. The orientation localizer is connected to the computer and configured to provide the encoder data of the angular position of the insertion-plane indicator to the computer. The computer computes the cross sectional image of the anatomy on the insertion plane corresponding to the angular position of the insertion-plane indicator.

[0033] In one embodiment, the computer computes a planned insertion angle of medical tools from the localized plane on the insertion plane and feeds back the information to the operator. The operator can interactively modify and/or confirm the planned insertion angle.

[0034] Fig. 1 depicts a system of a medical device guidance system 100 according to an exemplary embodiment of the present disclosure. The medical guidance device system 100 includes an orientation localizer 1, computer 15, image server 16, and image display 14. The computer 15 and the image display 14 are communicatively-coupled via a bus or local area network (LAN) to transmit/receive data between each other. The orientation localizer 1 and the computer 15 may be equipped with wireless equipment to transmit/ receive data between each other via wireless fidelity (WiFi) communication. Moreover, the computer 15 uses a wide area network (WAN) to connect and communicate with an image server 16 that is external of the medical guidance device system 100.

Specifically, the medical device guidance system 100 may be located in a sterile environment such as an operating room (OR), and the image server 16 may be located in a remote location which is a non-sterile environment. The image server 16 includes but is not limited to a PACS (picture archiving and communication system) server connected to a medical imaging device using the DICOM (Digital Imaging and Communications in Medicine) protocol. The medical imaging device can be a computer tomography (CT) modality, a magnetic resonance imaging (MRI) modality, a positron emission

tomography (PET) modality, single-photon emission computed tomography (SPECT) modality, a fluoroscopy modality, or any combination thereof. The computer 15 processes data provided by the orientation localizer 1 and data provided by images stored on the image server 16 in order to display images in the image display 14. Figs. 2A & 2B describe and show in detail the orientation localizer 1, which can be but is not limited to a disk- shaped or ring-shaped guidance device having adhesive sticker with markings thereon.

[0035] Figs. 2A and 2B show a top view and bottom view, respectively, of the orientation localizer 1 included in the medical device guidance system 100 according to an embodiment of the present disclosure. The orientation localizer 1 is a ring-shaped article of manufacture, such a needle guidance device having an adhesive part (e.g., sticker or patch) able to adhere to a patient's skin. The orientation localizer 1 includes a major angular scale 2, a minor angular scale 3, templates 4 (including templates 4A and 4B), an opening 5, a plurality of fiducial markers 6, and a reference marker 7. The major angular scale 2 and the minor angular scale 3 are ring-shaped scales arrayed concentric to each other around a center M. A first template 4A and a second template 4B are printed with visually identifiable indicia (e.g., numbers 1-9) over adjacent sections of the angular minor scale 3. Major angular scale 2 and minor angular scale 3 are reflections of each other and symmetrical as are template 4A and template 4B. On the backside of angular major scale 2, fiducial markers 6 are arrayed in a circular layout around center M. The fiducial markers 6 are asymmetrically distributed in a circle of rotation around the center M. The orientation localizer 1 is part of, or is used with, a medical instrument guiding device, such as a needle guidance device described in U.S. Patent No. 9,222,996.

< guidance process>

[0036] Fig. 3 is a flowchart illustrating a process for guidance of a needle according to an exemplary embodiment of the present disclosure. Initially, in Step Sooi a medical image is captured, for example a CT scan image, using a medical imaging modality.

[0037] Then, in Step S002 the medical image is sent to the image server 16, which is communicatively-coupled to the medical imaging device, where the medical image is stored. Here, the timing of when the medical image is captured and stored is irrelevant. The steps Sooi and S002 can occur during an ongoing medical intervention where needle insertion is required. Alternatively, the imaging and storing steps can occur prior to a medical intervention where needle insertion is required, and the images can be obtained by computer 15 from image server 16 during a needle insertion procedure.

[0038] Using the medical image stored in the medical imaging server 16, in Step S003 a physician determines the entry point on a patient where a needle will be inserted. This entry point is where the orientation localizer 1 will be mounted to the skin of the patient.

[0039] Upon mounting, in Step S004, the orientation localizer 1 is positioned so that center M of the orientation localizer is at a position 0 marking the needle entry point on the patient.

[0040] Next, in step S005 the physician performs image registration using the medical imaging device to obtain a set of medical images (scout scan). Figs. 6A & 6B show exemplary captured and/or reconstructed medical images. In the image registration process, the medical imaging device captures axial medical images 17 along an axial direction D, as shown in Fig. 6A. The axial direction D is in the longitudinal direction of the patient's bed. With the orientation localizer 1 mounted on the patient, during the capturing of the set of axial medical image, the orientation localizer 1 appears in the captured axial medical images 17, as seen in Fig.6A. Fig. 6A also shows the medical image set including the fiducial markers (dots) in the orientation localizer 1.

[0041] In Step S006 the fiducial markers 6 are automatically identified by the computer 15 by using an appropriate image processing algorithm (e.g., Hough transformation) to detect a circular shape.

[0042] Next, in Step S007 the computer 15 identifies the position and the orientation of the orientation localizer 1 by matching a known fiducial layout with the fiducial layout that the computer 15 identifies from the axial medical images 17. In this embodiment, since the fiducial markers 6 are asymmetric along a circumference of the circular array of the fiducial markers 6, the computer 15 can determine the orientation along the circumference of the fiducial layout while the center of the circumference of the identified fiducial layout is regarded as center M.

[0043] In Step S008, after the computer 15 determines the position and the orientation of the orientation localizer 1, the computer 15 automatically determines cross sectional medical images of the patient's anatomy on a localized plane 18 as shown in Fig. 6B.

[0044] The localized plane 18 is defined perpendicular to the Z-axis, and has an origin 0 where the Z-axis crosses the X and Y axes in a three-dimensional space. Fig. 8 is a perspective view of the three-dimensional space showing an insertion plane 19 and localized plane 18 according to an exemplary embodiment of the present disclosure. Local coordinates of origin 0 of the orientation localizer 1 is a vector F normal to the localized plane 18. The cross sectional medical images on the localized plane 18 can be defined on any plane parallel to the X-Y plane of the local coordinate 0. For example, in Fig. 6B the localized plane 18 is shown at a plane which shows an image of the orientation localizer 1 and the fiducial markers 6. Since the zero position or reference marker (13 in Fig. 4) can be aligned with the X-axis, the computer 15 then concurrently determines medical images of the patient's anatomy on insertion plane 19 as shown in Fig. 8. The insertion plane 19 is perpendicular to the localized plane 18 and includes an origin 0 of the local coordinate of the orientation localizer 1. The insertion plane 19 can be defined at any point along rotational direction G around the Z-axis of the local coordinate 0 of the orientation localizer 1. For example, an angular position of the insertion plane 19 is defined as angle φ, which is an angle between the insertion plane 19 and the X-axis of the local coordinate 0.

[0045] In Step S009 the computer 15 displays the cross sectional images of the patient's anatomy on the localized plane 18 and/or on the insertion plane 19 on the image display 14. The computer 15 can also display the angular portion of the templates 4 corresponding to the angular position of insertion plane 19, i.e. the angle φ. In Fig. 2, the image display 14 shows B-6 as the angular position of the templates 4.

[0046] In Step S010, the physician can visually confirm the cross sectional images on the localized plane 18 or on the insertion plane 19 and can make an insertion plan by defining a target position of the tip of the medical tool.

[0047] Upon confirmation, in Step Son the physician can determine an appropriate insertion plane 19 and mark the templates 4 with the selected insertion plane 19, for example templates 4A and 4B are shown in Fig. 2A. Also, the physician can confirm orientation of the line connected template 4A and 4B in relation to the reference marker 7 (the zero position). The reference marker 7 directs to the X-axis of the local coordinate 0. Therefore, the physician can easily find the template 4A by using both the template position (B-6 in Fig. 1) and angle φ (35 deg in Fig. 1).

[0048] After marking on the templates 4A & 4B, the physician can use the marked templates 4A & 4B as landmarks of the insertion plane 19 where the physician plans to insert a medical tool. Since the orientation localizer 1 is mounted on the patient, the orientation localizer 1 can provide an insertion landmark even when the patient moves accidentally.

[0049] During the procedure, the medical guidance system 100 can update the image registration of the orientation localizer 1 in every image acquisition by performing automatic image re-registration.

[0050] Fig. 4 is a plan view of an orientation localizer 1 according to another embodiment of the present disclosure. Here, orientation localizer 1 includes a rotatable body 9 and a stable body 10. The rotatable body 9 is a ring that can rotate against the stable body 10 and has an insertion-plane indicator 8. The stable body 10 includes a plurality of fiducial markers 6, connection socket 11, and communication cable 12.

Moreover, the socket 11 has a zero position marker 13.

[0051] In the orientation localizer 1, a rotary encoder (not shown) is located in the stable body 10. Also, the rotary encoder scales are located in the rotatable body 9. The rotary encoder measures the rotation angle from the zero position marker 13. The communication cable 12 powers the rotary encoder and allows for two-way

communication to send and receive the rotary encoder signals to/from the computer 15.

[0052] Fig. 5 depicts a system of a medical device guidance system according to yet another embodiment of the present disclosure and will be described with reference to Figs. 4 and 8. The computer 15 determines the cross-sectional images on the insertion plane 19. Since the insertion plane 19 corresponds to the rotation of the rotatable body 9, the computer 15 determines the cross-sectional images on the insertion plane 19 by using the rotary encoder signals received via the communication cable 12. The computer 15 also updates the cross-sectional images in real time while synchronizing to movement of the rotatable body 9. This allows a physician to confirm different images by rotating the rotatable body 9 without having to refer back and forth between the image display 14 and the patient. Once the physician finds an optimal insertion plane 19, the physician can use the insertion-plane indicator 8 as a landmark for the optimal insertion plane 19.

[0053] Upon determining the optimal insertion plane 19, the physician then determines the target position for the tip of the medical tool on the insertion plane 19. Since the skin entry point is already determined, a needle trajectory 20 is defined by connecting the skin entry point and the target position for the tip of the medical tool. Afterwards, the computer 15 determines an insertion angle Θ between a needle trajectory 20 and the Z-axis of the local coordinates, as shown in Fig. 8. This allows the computer 15 to display, on the display 14, the insertion angle Θ as well as the angle φ of the insertion plane with respect to the X-axis direction. As discussed elsewhere in this application, the zero position is aligned with the X-axis.

[0054] The physician can then use these angles (the insertion angle Θ as well as the angle φ of the insertion plane) to guide the medical tool along the planed needle trajectory 20 by using the orientation localizer 1. In this manner, the orientation localizer 1 mounted on the patient serves as a landmark for both the insertion angle Θ as well as the angle φ of the insertion plane 19. As an option, the insertion angle Θ can be replaced by different notation of the insertion angle Θ. For example, the computer 15 can provide calculations based on the height of the medical tool on the circumference of the rotatable body 9.

[0055] Fig. 7 is a plan view of an orientation localizer 1 of yet another embodiment of the present disclosure. Here, the orientation localizer 1 is integrated within the rotatable body 9 and the orientation localizer 1 has a touch screen 21 (for tactile input) with LEDs (light emitting diodes) arrayed along the circumference of the rotatable body 9. The touch screen 21 with LEDs can detect the touch (tactile input) of a user, and, in response to the touch, the computer 15 will change the position of the insertion plane and will change the lit LEDs (e.g. 21A & 21B) to indicate the orientation of the insertion plane 19.

[0056] Since the rotatable body 9 of Fig. 7 has the touch screen 21 which covers the rotatable part, the orientation localizer 1 is able to be packaged with a sterile cover without pinching the packaging between the rotating and stable parts thus reducing the presence of a narrow gap between parts. Accordingly, the orientation localizer l of this embodiment can reduce difficulty in sterilization and make management of sterilization easier.

[0057] According to a second embodiment, a medical guidance system to guide a needle-like medical tool comprises: a guidance device configured to guide the needle-like medical tool to an intended trajectory; and a computer to retrieve at least one of medical images among CT, MRI and Fluoroscopy images, and to display the intended trajectory with the medical images. The guidance device comprises: a base plate including an baseplate opening, and a bottom surface configured to be mounted to a patient; a rotatable ring that is attached to the base plate and aligned with the base-plate opening; the rotatable ring includes a movable-ring opening aligned to the base-plate opening to form an main opening to access to the patient; and a guidance part mounted on the rotatable ring to guide the needle-like medical tool along the intended trajectory.

[0058] The guidance device further comprises a rotary encoder. The rotary encoder includes a rotary scale mounted on the movable ring; a sensor head mounted on the base plate; a sensor circuit board connected to the sensor head and configured to compute an angular position of the rotary scale by processing sensed signals from the sensor head.

[0059] The guidance device further comprises fiducial markers mounted on the base plate and configured to be visible in the medical images. The guidance device further comprises a circuit box comprising: a memory unit having guidance device information to define a geometrical relation between coordinates of the rotary encoder and coordinates of the fiducial markers; and a microcontroller connected to the memory unit and to the sensor circuit board, and configured to communicate with the computer.

[0060] The computer is configured to calculate a geometry of the fiducial markers in the medical images with relation to the coordinate of the medical images.

[0061] In the medical guidance system, either the computer or the microcontroller is configured to compute a relation of the coordinates of the guidance device with the coordinate of the medical images by using the device information in the memory unit and the geometry of the fiducial markers calculated by the computer

[0062] In the medical guidance device according to one embodiment, the rotary encoder is configured to measure absolute angular position of the rotary scale.

[0063] In the medical guidance device, the microcontroller is configured to send the device information to the computer, and the computer computes a relation of the coordinate of the guidance device to the coordinate of the medical images by using the device information in the memory unit and the geometry of the fiducial markers.

[0064] In the medical guidance device, a circuit box includes a wireless communication unit and a battery to power the guidance device. The circuit box wirelessly communicates with the computer by using the wireless communication unit.

[0065] Fig. 9 is a functional block diagram illustrating a medical guidance system 100 according to another embodiment of the present disclosure. In this embodiment, the medical guidance system 100 transmits and receives data to/from an image server 113 that receives image information from a medical imaging device 114. The medical guidance system 100 includes a computer 15 and an orientation localizer 1 that are communicatively-coupled via a bus 117. The image server 113 includes, but is not limited to, a PACS and/or DICOM server or equivalents thereof that receives and stores image information from the medical imaging device 114. The medical imaging device 114 includes, but is not limited to, a computed tomography (CT) scanner, magnetic resonance imaging (MRI) scanner, positron emission tomography (PET) scanner, single-photon emission computed tomography (SPECT) scanner and/or fluoroscopy scanner.

[0066] The computer 15 of the medical guidance system 100 includes a user interface 115 allowing a user to access and control the computer 15 and navigation software 116 to determine proper insertion angles of a needle-like medical instrument into a patient based on image data received from the medical imaging device 114 and stored in the image server 113. Additionally, the navigation software 116 provides a medical professional with information including, but not limited to, protocols involving the use of the orientation localizer 1 and visual orientation and location information of the orientation localizer 1.

[0067] The orientation localizer 1 includes a guidance part 109, a rotatable ring 9, a stable (non-rotating) ring 10, and a circuit box 103. The rotatable ring 9 includes a rotary scale 106. The stable ring 10 has a sensor head 105 and a sensor circuit board 107. The circuit box 103 includes a microcontroller 110 and a memory unit 111. Portions of the rotatable ring 9 and the stable ring 10 make up a rotary encoder 4. The rotary encoder 4 includes the rotary scale 106 of the rotatable ring 9 and the sensor head 105 and sensor circuit board 107 of the stable ring 10.

[0068] In yet another embodiment of the present disclosure, the medical guidance system 100 operates very similarly with the orientation localizer 1 instead being replaced by a guidance device. The guidance device includes the elements of the orientation localizer 1 with the small difference of the stable ring 10 being replaced by a base plate and the rotatable ring 9 being replaced by a moveable ring. All other elements of the system remain the same as those shown in Fig. 9.

[0069] Figs. 10A and 10B are two views of the orientation localizer 1 according to the embodiment as described in Fig. 9 of the present disclosure. Fig. 10A is a top view of the orientation localizer 1 and Fig. 10B is a cross sectional view at an A-A line viewed in the direction of arrows A, as shown in Fig. 10A. The A-A line bends at point C at a right angle to see two cross sectional views in the one figure shown in Fig. 10B. In the present embodiment, all features disclosed in Figs. 10A and 10B are similar with and correspond to the orientation localizer 1, the stable ring 10, and the rotatable ring 9 (shown in Figs. 4 and 7) being replaced by a guidance device, a base plate and a moveable ring, respectively.

[0070] In Fig. 10B the stable ring 10 has a mounting surface 120 situated on the bottom. The mounting surface 120 is mounted on the skin surface of a patient and the stable ring 10 adheres to the skin of the patient via the mounting surface 120.

[0071] In Fig. 10A the stable ring 10 includes fiducial markers 121A, 121B, 121C and 121D at four corners. The fiducial markers 121A, 121B, 121C and 121D are visible optically as well as in CT and X-ray images utilizing radio-opaque material. The radio-opaque material can be, but are not limited to, plastic including fillers of Barium Sulfate, bismuth subcarbonate, bismuth oxychloride, tungsten.

[0072] At each corner, the fiducial markers form a cluster of markers with different numbers of fiducial markers than each other. Therefore, the position and the orientation of the stable ring 10 can be geometrically distinguished using only one or more the fiducial markers 121A, 121B, 121C and 121D in the CT and X-ray images.

[0073] Moreover, as shown in Fig. 9, the stable ring 10 includes portions of the rotary encoder 4, which includes a sensor head 105 and the sensor circuit board 107. The sensor head 105 faces the rotary scale 106, which is mounted on the rotatable ring 9, and is electrically connected to the sensor circuit board 107. The sensor circuit board 107 processes measurement signals of the angular position of the rotary scale 106 by the sensor head 105, and outputs the angular position to the microcontroller 110.

[0074] The stable ring 10 is ring-shaped and engages with the rotatable ring 9. Referring to Fig. 10B, the rotatable ring 9 is rotatable around the axis E with a rail on the stable ring 10. The axis E passes through point C on the mounting surface 120. Also, stable ring 10 and rotatable ring 9 have seal structures to protect the sensor head 105 and rotary scale 106 from contamination in an external environment.

[0075] The rotatable ring 9 has the rotary scale 106 where the rotary scale 106 is fixed onto the rotatable ring 9 and can rotate together with rotatable ring 9. The sensor head 105, rotary scale 106, and sensor circuit board 107 form the rotary encoder 4.

Rotary encoder 4 measures an angular position of the rotatable ring 9 against a zero position of the stable ring 10.

[0076] As shown in Fig. 9A, the rotatable ring 9 mechanically connects to a guide part 109. The guide part 109 is detachable from rotatable ring 9 with a mechanical coupling between the rotatable ring 9 and the guide part 109. As shown in Fig. 10B, the guide part 109 includes a ring frame 1091 and an arc shape guide 1092. The ring frame 1091 is monolithically made with the arc shape guide 1092; the ring frame 1091 includes a slotted portion (space) 18 to release a needle-like medical tool (not shown). The arc shape guide 1092 bridges on the ring frame 1091 over the main opening 119. The arc shape guide 1092 also includes an insertion-plane indicator 8 and angular reference marks 30. The insertion-plane indicator 8 includes an axis E and has thickness D to create a guidance area toward arrow G as shown in Fig. 8 and FIG. 10A.

[0077] The angular reference marks 30 are line marks to signify an angle around point C on the insertion-plane indicator 8. By rotating the rotatable ring 9 around axis E, the angular reference marks 30 also rotate around axis E with the insertion-plane indicator 8. By using the angular reference marks 30 and the rotatable ring 9, the orientation localizer 1 localizes the insertion plane and further localizes fine grids of a remote center of motion with point C. The grids are cone-shaped grids with generator B along the point C as a pivot.

[0078] The remote center of motion models a physician's maneuver of a needlelike medical tool. Thus, point C is aligned to a skin entry point of the medical tool, which is defined by considering obstacles close to the patient's skin. With the fixed point C, the physician can select an intended trajectory to the target by using an appropriate position of the rotatable ring 9 and the angular reference marks 30.

[0079] After determining the position of rotatable ring 9 and the angular reference marks 30, the physician can insert the needle-like medical tool with guidance from the insertion-plane indicator 8 at the target angular reference marks 30.

[0080] Fig. 11A is a schematic illustration of the orientation localizer 1 according to yet another embodiment of the present disclosure. More specifically, the configuration of the circuit box 103 with the rest of the guidance system 100 (shown in Fig. 9) is described in more detail. In Fig. nA the circuit box 103 as described in Fig. 9, includes a microcontroller 110, a memory unit 111, a battery (not shown), and a wired or wireless communication unit (not shown).

[0081] The microcontroller 110 processes information from the computer 15 and the sensor circuit board 107 and the microcontroller 110 communicates with the computer 15 and the sensor circuit board 107 to exchange commands and target information between them. Specifically, the microcontroller 110 initiates and sends the angular position of the rotatable ring 9 measured by the rotary encoder 4 to the computer 15, as needed.

[0082] The microcontroller 110 is also electrically-connected to the memory unit 111. The memory unit 111 stores at least transformation matrices of the orientation localizer 1 based on local coordinates of the orientation localizer 1, which is determined as design. The microcontroller 110 then retrieves and sends these transformation matrices in the memory unit 111 to the computer 115, when the navigation software 116 requires them.

[0083] Specifically, the circuit box 103 in Fig. 11A is electrically-connected to the rotary encoder 104 at the sensor circuit board 107 in the stable ring 10 via the electric cable 122, as a separate part from the stable ring 10. Consequently, the circuit box 103 in Fig. 11A can be placed bedside or near the patient close to an area of intervention, but at a separated place from the stable ring 10. With the circuit box 103 in Fig. 11A, the stable ring 10 can reduce the footprint and reduce the area needed for the intervention. Also, the circuit box 103 in Fig. 11A includes an indicator 123 (such as a LCD or LED display). The indicator 123 displays the real-time angular position of the rotatable ring 9 with a digital indicator. Moreover, the indicator 123 displays different information about the orientation localizer 1, for instance the target angular position of the rotatable ring 9, the target angular reference mark (zero position), comparison between the target and current angular position of the rotatable ring 9, and the remaining battery power. With the indicator 123 on the circuit box 103, as shown in Fig. 9A and Fig. 11A, the physician can confirm the information on the orientation localizer 1 on the spot without having to leave the patient and the area of the intervention.

[0084] Fig. 11B shows a schematic illustration of the orientation localizer 1 according to another embodiment of the present disclosure. More specifically, Fig. 11B shows an alternate configuration of the circuit box 103 with the rest of the components in the guidance system 100. In Fig. 11B the circuit box 103 includes a microcontroller 110, a memory unit 111, a battery (not shown), and a wireless communication unit (not shown). This is similar to the embodiment described in Fig. 11A, however the circuit box 103 in Fig. 11B is monolithically fixed on the stable ring 10. Therefore, the risk of tangling cables with other objects in the surgical field are reduced. Nevertheless, in this case too, the circuit box 103 includes an indicator 123.

[0085] Fig. 12 is a flowchart illustrating a process for guidance of a needle using the medical guidance system 100 of the present disclosure. In step S1201 a physician takes medical images using a medical imaging device 114 (medical imaging modality). The medical device 114 is a CT scanner in this particular embodiment. The medical device 114 sends the CT images to the navigation software 116 in the computer 15 via the image server 113. Alternatively, the computer 15 actively obtains the CT images from the CT scanner or the image server 113.

[0086] At step S1202, with the CT images, the physician defines targets for percutaneous intervention with a needle-like medical tool and the skin entry point. At the same time, by virtually connecting the target to the skin entry point in the image, the physician can determine the plane for the trajectory of insertion of the needle-like medical tool using the navigation software 116. Also, in this step, the physician marks the skin entry point on the patient which is standard practice using for example, grid visible markers on the patient.

[0087] In step S1203 the physician sets up the needle guidance device to calibrate it and sets a proper initial state of the orientation localizer 1. More specifically, device setting-up at S1203 includes setting up the rotary encoder 104 to establish an original zero position properly; this will be explained in more detail in Fig. 14.

[0088] After setting up the device, in Step S1204 the physician mounts the orientation localizer 1 onto the patient and aligns the point C in Figs. 10A & 10B to the skin entry point, and then affixes the orientation localizer 1 onto the patient with adhesive tape or the like.

[0089] In Step S1205, after the device mounting, the physician takes CT images including the orientation localizer 1 and sends the CT images to the navigation software 116. Using the CT images with the orientation localizer 1 showing, in Step S1206, the physician conducts device-to-image registration. In this step S1206, the navigation software 116 recognizes the position and orientation of the orientation localizer 1 on the patient in the CT images, i.e. in the coordinate of the CT image, by using fiducial markers 121A, 121B, 121C and 121D as described in Figs. 10A and 10B. This fiducial marker detection can be manually performed by physician instruction with user interface 115 or, can be fully automated by using a computer algorithm. The navigation software 116 can also reflect the plan of the trajectory with two device parameters, which are the angular position of the rotatable ring 9 (θ| ) and the insertion angle on the insertion-plane indicator 8 (flff ^s ) at this step. Device-to-image registration will be discussed further with respect to Fig. 13.

[0090] In step S1207, the physician can be prompted by the computer 15 to confirm whether the device-to-image registration is appropriate or not, by executing the navigation software 116. If the device-to-image registration is not appropriate a need for re-registration is reached (YES is Step S1207). In the case that re-registration is required, the physician can conduct Step S1206 the device-to-image registration again.

[0091] If the device-to-image registration is appropriate, re-registration is not required (NO in Step S1207), then the flow proceeds to Step S1208 where the physician can send the target device parameters fif , 6ff ^H to the microcontroller no.

[0092] Afterwards in Step S1209, the physician manually rotates the rotatable ring 9 while the navigation software interactively updates the cross sectional image on the guide surface by using the real-time angular position of the rotatable ring 9 from the microcontroller 110. Also, the microcontroller 110 compares the real-time angular position of the rotatable ring 9 with the target angular position received from computer 15 at S1208. Once the rotatable ring 9 reaches the target angular position (parameters θ _$ , Sp ^S ), the microcontroller informs the navigation software 116 and indicator 123 of the end of targeting of the rotatable ring 9. Then, the navigation software 116 and/or indicator 123 informs the physician of the end of targeting.

[0093] Upon establishing the target angular position of the rotatable ring 9, in Step S1210 the physician picks the specific angular reference mark 30 indicated by the target insertion angle on the insertion-plane indicator 8 and with the specific angular reference mark 30, the physician inserts the needle-like medical tool from the skin entry point to the target using the guidance system 100.

[0094] In Step 1211 after the first attempt of the insertion, the physician takes CT images of the inserted needle-like medical tool, the orientation localizer 1, and sends the CT images to the navigation software 116. With the CT images of the inserted needle-like medical tool, the physician evaluates the position and orientation of the inserted needlelike medical tool.

[0095] In step S1212, the position of the inserted needle-like medical tool is evaluated. Specifically, if the physician determines the position is suboptimal, the position is determined to be not proper (No in Step S1212), flow proceeds back to Step S1207 where a decision is made as to whether re-registration should be performed. If registration is not necessary, at Step S1208, the physician can update the trajectory to improve the position of the needle-like medical tool with navigation software 116. At the same time (in real time), with the latest CT image, the physician finds the dislocation or displacement of the target, skin entry point and the orientation localizer 1, and updates the registered position and orientation of the orientation localizer 1. Thus, the physician can conduct the device-to-image registration with the latest CT images. By updating the device-to-image registration, the physician can reduce discrepancy of the actual geometrical relationship between the orientation localizer 1 and the target. Specifically, since the orientation localizer 1 is mounted on the patient and can move with the patient body together, the update of the device-to-image registration can effectively compensate rigid dislocation of the patient from the older (initial) CT images.

[0096] With updated plane of the trajectory and the device-to-image registration, the physician can perform another attempt of the insertion with the same steps S1208- S1211 as in the first attempt.

[0097] In step S1212, if the position of the inserted needle-like medical tool is checked and the physician is satisfied with the results (Yes in Step S1212), flow continues to Step S1213. In Step S1213, a determination is made as to whether insertion of another needle-like medical tool is needed. If insertion of another needle-like medical tool is needed (Yes in Step S1213) flow returns back to Step S1208. At step S1208, the process continues as described above, so that an additional needle is inserted. Optionally, in some instances where high-accuracy is required or where the patient accidentally moves, the flow returns to step S1205, so that new CT images and new device-to-image registration are performed. If insertion of another needle-like medical tool is not needed (No in Step S1213) flow is complete and therefore ended.

< device-to-image registration mathematical model >

[0098] Fig. 13 is a schematic illustration of the transformation of local coordinates for explaining the device-to-image registration as described in Step S1206 of Fig. 12. A computation process to obtain a relative transformation matrix for device-to-image registration can be computed by the transformation process shown in FIG. 13. To that end, the navigation software 16 is programmed to reflect the plan of the trajectory with two device parameters, which are angular position of the moving ring 9 (θζ) and insertion angle on the insertion plane 19 (8f ^E ).

[0099] Sigma∑ signifies an overall consideration of all local coordinates according to each of the subscripts. In the device-to-image registration, the local coordinates of each element (fiducials, movable ring, guide, obtained image) need to be handled individually in consideration of an overall transformation. The first aspect to consider is the local coordinates of the patient in world-space when taking the medical images vimage> This is a fundamental coordinate to express the plane of the trajectory for the instrument, the target's location (e.g., the center location of an anatomy in the patient), and the skin entry point in computing the transformation with the navigation software 116.

Specifically, the physician correlates the coordinates of the patient with the physical world. The second aspect to consider is the coordinate of the fiducial markers 121, e.g., when the guide device shown in Figs. 10A-10B is used, the coordinates of the stable ring 10 is considered. The third aspect to consider is the coordinate of the rotatable ring 9, which rotates with the rotatable ring 9 against the stable ring 10 by the angular position of the rotatable ring 9 (θζ). The fourth aspect to consider is the coordinate for guidance of the needle-like medical tool. In an exemplary embodiment of the present disclosure, one axis (a first axis) of the coordinate system passes along the target trajectory. One of the other axes (a second axis) is on the insertion-plane indicator 8 (see Fig. 10A). And a third axis is perpendicular to the second axis and parallel to the localized plane 18. Therefore, this insertion plane can rotate along the angular reference marks 30 depending on the target insertion angle of B^ ^R on the insertion-plane indicator 8.

[00100] T signifies a coordinate transformation, which is a 4 by 4 homogeneous transformation matrix. The superscript on T signifies a base coordinate, and the subscript on T signifies an objective (or destination) coordinate for the transformation. That is, the transformation T relates the base coordinate defined by the superscript of T to the destination or objective coordinate defined by the subscript of T. The coordinate transformation can be expressed with a homogeneous transformation matrix for the three-dimensional space, which includes a four-by-four matrix to define the geometrical relationship between two coordinate systems (e.g., the transformation from a Cartesian coordinate system to an angular or polar coordinate system).

[00101] The four transformations 126, 127, 128 and 129 can be defined among the four local coordinates. The goal of the device-to-image registration is to establish the following equation (1) among the four transformations 126, 127, 128 and 129.

■IM

G rJ?(pi ^M ) ¾ _H (e¾ i**(ej ^« ) eq. (1)

[00102] Where, transformation 126 is a transformation that relates the coordinates (position and orientation) for guidance (subscript G) of the needle-like medical tool based on the coordinates (position and orientation) of the acquired medical images (IM) of the patient. This transformation 126 is given by, or is equal to, a combined or correlated result of transformation 127 which is a transformation to the coordinate of the fiducial markers (F) from the coordinate of the medical images (IM), where p{ is a set of position vectors of all fiducial markers on the coordinate of the medical image, transformation 128 r^ _s (e ) which is a transformation to the coordinate of the movable ring (MR) from the coordinate of the fiducial markers (F), where θζ is an angular position of the rotatable ring 9 based on the coordinate of the fiducial markers, and transformation 129 ^& 0f ^s ) which is a transformation to the coordinate for guidance (G) of the needle-like medical tool from the coordinate of the movable ring (MR), where B^ ^R is the insertion angle on the Insertion-plane indicator 8 (P) based on the coordinate of the movable ring (MR).

[00103] In equation 1, the navigation software 116 can determine the target values of the device parameters of the angular position of the rotatable ring 9 (£? ) and insertion angle on the insertion-plane indicator 8 (0f ^s ) with the specific position of the base plate, i.e. the position vectors of the fiducial markers at the actual position of the i-th image (pf ^&T ), from the target trajectory.

[00104] The transformation to the coordinate for guidance (G) of the needle-like medical tool based on the coordinates of the medical images (IM) of transformation 126 Τ¾ ^Μ of equation 1 is determined by the navigation software 116 using two position vectors; a first vector is that of the skin entry point and the second vector is that of the target based on the coordinates of the real-time medical images. In Step S1202 of Fig. 12, when the physician defines the skin entry point and the target in the CT image, the navigation software 116 can compute this transformation with the initially defined positions in the CT image. However, as the processing flow of FIG. 12 progresses, at step S1206, the navigation software 116 uses real-time images (images taken at S1205) for device-to- image registration.

[00105] Specifically, the parameters p[ ^M are determined, when the navigation software 116 gets the positions of fiducial markers 121A, 121B, 121C and 121D in the CT images taken at step S1205. Therefore, if the navigation software 116 knows the matrix forms of Ί¥*( Ι ^Μ ), Tf _m (βζ), Τ * the navigation software 116 can derive the parameters $g,and 6p ^S from the plan of the trajectory.

[00106] The matrix forms for coordinates transformation 127 T _F jy * ), transformation 128 T _R (#f ), and transformation 129 T^ ^R [&f ^s ) are defined by the geometrical design of the orientation localizer (including the fiducial markers, the movable ring, and the guide part), and the actual assembling errors and/or

manufacturing tolerances. The matrix form of transformation is dependent on the design and configuration of the fiducial markers 121. The matrix form design, for example the size of each component, and position of the movable ring on the base plate or stable ring and so on. The matrix form F _: ^ε ($ f ^R ) is defined by the design of the guide part 109. When the orientation localizer 1 undergoes a design change, the forms of the transformation matrices also need to be updated. Therefore, the navigation software 116 always needs to apply the matrix forms of these transformations corresponding to the actual design parameters of the orientation localizer that the physician is using for the given intervention.

[00107] In order to keep and guarantee correspondence between the forms of transformations 127, 128, 129 and the actual design of the orientation localizer that the physician is using, the orientation localizer 1 includes the device information on the forms of transformations 127, 128, 129 stored in the memory unit 111. In this manner, during an interventional procedure, the computer 15 executing the navigation software 116 asks the microcontroller 110 for the device information on the forms of the transformations 127, 128, 129, and establishes the equation 1 with the parameters.

[00108] Since the correspondence between the transformations 127, 128, 129 and the actual orientation localizer is established only on the orientation localizer side, the navigation software 116 does not need to be updated and prepare dedicated device tables for every possible orientation localizer. The navigation software 116 can ask the microcontroller 110 for the device information as one universal action for different designs and individual parameters of the orientation localizer.

[00109] Also, with equation 1, the navigation software 116 can display the cross sectional images on the real-time position of the insertion-plane indicator 8. The navigation software 116 can apply the real-time angular position of the rotatable ring 9 measured by the rotary encoder 104 to #§ in the transformation 128, and synthesize the cross sectional images on the insertion-plane indicator 8. The real-time cross sectional images can help the physician intuitively confirm whether a critical anatomy surrounding the target exists, or whether the targets themselves and the treatment area around the target, for example an ablation area, are in the planned insertion trajectory.

[00110] Fig. 14 is an extracted flowchart of Fig. 12 detailing the sub-steps for device set up described in Step S1203 for embodiments with the rotary encoder 4 measuring incremental angular position and absolute angular position respectively. [00111] The device setting-up in Step S1203 of Fig. 12 includes the sub-steps of device powering on at sub-step S1401, device calibration at sub-step S1402, and confirmation of calibration at sub-step S1403, as shown in Fig. 14. First, in sub-step S1401 of Fig. 14, the physician powers ON the orientation localizer 1. Upon powering the device ON, the rotary encoder 104 with the incremental angle measurement does not yet define the correct angular position of zero. As such, in sub-step S1402 the physician needs to perform device calibration to establish the correct angular position of zero. That is, the device calibration sub-step S1402 includes calibrating the orientation localizer 1 to a zero position. The zero position can be a predetermined or predefined position, such as a position given by the zero position marker 13 shown in Fig. 7, or the zero position can be defined at any position (e.g., given by an absolute encoder position) along the

circumference of rotation of rotatable ring 9 with respect to which an angular

displacement can be measured. This can be done with manual or electronic alignment of the rotatable ring 9 to the mechanical reference for the correct zero position. With the zero position established, the physician can teach the correct angular position of zero to the medical guidance system 100.

[00112] After the device calibration, in sub-step S1403 the physician confirms whether a re-calibration is required, and decides whether to proceed to mounting the device on the patient in Step S1204 of Fig. 12. If re-calibration is necessary (Yes in sub- step S1403) the flow returns to sub-step S1402 to calibrate. If no re-calibration is needed (No in sub-step S1403) the flow proceeds to Step S1204 and the device in mounted on the patient.

[00113] The device setting-up steps of Fig. 14 are required for every device for every intervention. In addition, if the physician needs to turn the guidance device off for some reasons, and then re-start the medical guidance system, these steps are also required. For example, in instances where an interventional procedure is stopped and the medical guidance system is re-started, these device setting-up steps are required to ensure that the orientation localizer remains aligned to the correct zero position. In this case, since the device is already mounted on the patient, and if a determination for re-calibration is not required (No in Step S1403), the duration of the intervention can be reduced. Also, if the navigation software 116 determines that recalibration is not required, the medical guidance system with the rotary encoder 104 to measure absolute angles, can

advantageously reduce a risk of human-factor errors and lower the mental load of the operator to use the system.

[00114] As described above, in step S1212, the position of the inserted needle-like medical tool needs to be evaluated for proper positioning. Then, if the physician determines the position is suboptimal, the position is determined to be not proper and a decision is made as to whether re-registration should be performed. In order to evaluate the needle position, computer 15 is programmed to execute the navigation software 116 and display one or more images of the planned trajectory and/or the inserted instrument.

< interactive display and evaluation of medical guidance by interlocking display of axial image and reconstructed image of device plane >

[00115] When a user needs to evaluate an out of plane needle insertion with a set of the axial images, it is difficult for the user to understand the direction of flipping the axial images against the anatomy (e.g., tumor) of a patient to confirm the needle insertion direction. Since the medical instrument (needle or probe) is inserted according to the device parameters ^θ ε ^e P ^S , it would be easier to evaluate the needle insertion trajectory by observing a reconstructed image along the device plane. However, reconstructed images (along the device plane) are also difficult to understand due to unclear relationship to the axial images, and its slice orientation against the patient.

[00116] Figs. 15 and 16 show an exemplary embodiment for interactively displaying and evaluating a planned trajectory and/or an actual trajectory of an inserted instrument. According to this embodiment, it is advantageous to interactively display and evaluate medical guidance effectiveness by interlocking the display of an axial image and the reconstructed image of device plane. Each of Figs. 15 and 16 shows a set of axial images 17, an insertion plane image 190, and an image of orientation localizer 1. In this embodiment, the navigation software 116 displays the axial scan images 17, the insertion plane image 190, and (optionally) the image of orientation localizer 1, on the image display 14. These images may be displayed simultaneously side-by-side in a single or multiple display screens, or the images may be alternately displayed, as desired. As understood from Fig. 12, the orientation localizer 1 is already mapped to the CT image coordinates with its position and orientation established during the device-to-image registration.

[00117] The navigation software 116 has reconstructed the insertion plane image 190 based on the insertion plane indicator 8. Therefore, when the user (a physician) needs to evaluate proper positioning, the user rotates the insertion plane indicator 8 along rotational direction G around the rotation axis E, and the insertion plane image 190 will be updated consistently. The rotation of the insertion plane indicator 8 and the updating of insertion plane image 190 are synchronized with each other in real-time.

[00118] When CT images include a patient anatomy 1002 and a needle trajectory 1006, the needle trajectory 1006 can be a planned needle trajectory and/or a trajectory of an inserted needle. However, in the axial scan images 17, if the insertion orientation is not perpendicular to the axial scan direction, the needle trajectory 1006 is delineated only partially in the observed axial image 17. This observation of the partial image of the needle trajectory 1006 would cause physicians to understand the needle orientation in the real three-dimensional space. However, to observe the entire length of the needle trajectory 1006, multiple axial scan images 17 are necessary. Therefore, physicians will check multiple axial scan images and reconstruct the needle orientation with multiple partial images of the needle trajectory 1006 from different axial scan images.

[00119] In this embodiment, to facilitate users' understanding and to expedite the evaluation process, the axial scan image 17 is linked (interlocked) to an axial plane indicator 1005 on the insertion plane image 190. The axial plane indicator 1005 represents at least one axial scan image 17 at crossing line between the axial scan image 17 and insertion plane image 190. In this manner, when the user moves the axial scan image 17 to orientation in the D direction, the axial plane indicator 1005 will simultaneously move (translate) to orientation B on the insertion plane image 190. The user also can move the axial plane indicator 1005 in the B direction to move the axial scan image 17 in the D direction.

[00120] With this embodiment, the physician can intuitively find the desired needle trajectory 1006 on the insertion plane image 190 by rotating the insertion plane indicator 8 around the axis E in a rotational direction G. Since the rotational direction G is also interlocked with the axial plane indicator 1005, the user can easily map the axial scan image 17 to the insertion plane images 190 with the axial scan indicator 1005. Especially, since the axial scan indicator 1005 is synchronized with the axial scan image 17 and with the rotational direction G of the insertion plane indicator 8, physicians can intuitively understand where the partial needle trajectory 1006 on the axial scan image 17 stems from. In this manner, the physician can easily comprehend the flipping direction of the axial scan images 17 along the needle trajectory 1006, when the physician is checking the partial needle trajectory 1006 on the axial scan images 17 by flipping multiple axial scan images 17.

[00121] The embodiment of Fig. 15 is particularly beneficial to reduce the duration of operation, and to minimize human factor errors when the physician plans or executes multiple needle trajectories 1006.

[00122] Fig. 16 explains further features based on the aforementioned embodiment of Fig. 15. In the embodiment according to FIG. 16, trajectory indicators or limiters 1008 and 1007 are displayed on the insertion plane image 190. Here, two pointers in the reconstructed image along the insertion plane image 190 are used to select sets of the axial images between those pointers.

[00123] The user can interactively define these limiters 1008 and 1007 on the insertion plane image 190 by touch or point-and-click operations. The image limiters 1008 and 1007 can be slide-able along the needle trajectory 1006, and define a range 1010 for the set of axial scan images 17.

[00124] With the image limiters 1008 and 1007, the user can easily limit the range 1010 of the axial scan images 17 to a set to investigate the needle trajectory 1006. In one embodiment, the navigation software 116 can be configured to automatically set the image limiters 1008 and 1007 based on the skin insertion point of the needle trajectory and the target of the planned or actual needle trajectory. In other embodiments, the trajectory indicators or image limiters 1008 and 1007 an also be defined by the size and shape of an anatomy (organ or tumor) of the patient. When the image limiters 1008 and 1007 are defined by the size and shape of an anatomy, the user can more closely evaluate if the insertion trajectory is effective to avoid undesired damage to critical organs.

[00125] Advantageously, by interlocking the display of axial image and

reconstructed image of the device plane, the reconstructed image on the device plane is updated in real-time, in response to actual device motion. One or more axial images can be displayed on the same screen as the reconstructed image on the device plane, and all images can be interactively updated in real-time. The reconstructed image is superposed with a line symbol of the axial image on the location to cross to the reconstructed image. The line symbol interlocks with the axial image when the user changes the display of axial image.

[00126] The medical guidance device using an orientation localizer as described herein provides a tangential plane of the image around the skin entry point on the patient that the medical tools is planned to be inserted as a localized plane. Therefore, the physicians can easily plan the target insertion point in the lesion by using the plane close to the plane perpendicular to the medical needle, and can confirm a critical anatomy that the physician needs to exclude from the trajectory of the medical tools only by using the localized plane as a representative plane even when multiple medical tools are planned to be inserted. Moreover, since this localized plane is consistent between the image in the computer and the orientation localizer against the patient, the physicians can use the orientation localizer as a landmark of the insertion angle for the medical tools.

[00127] The medical guidance device disclosed herein also provides the insertion plane perpendicular to the localized plane. Advantageously, physicians can plan the insertion trajectory of medical tools out of the axial imaging of the medical imaging device without complex maneuver to define the insertion plane and an insertion trajectory in 3D images.

[00128] The medical guidance device described herein further provides physical angular scales to indicate the insertion plane that the physicians confirm as the image in the display. Therefore, the physician can easily determine the insertion plane out of the axial imaging plane and can reduce the insertion parameters and complexity of the insertion maneuver when the physicians need the insertion trajectory of the medical tools that are not on the axial imaging plan of the medical imaging device. Moreover, in some embodiments the orientation localizer includes angular scales that do not require electronics to maintain consistency of the angular position of the insertion plane.

Therefore, the medical guidance device can be developed with reduced number of the parts and can increase reliability of operation. Also, the orientation localizer can be easily sterilized with variety of material options, and/or can be disposable at a reasonable cost.

[00129] In some embodiments the medical guidance device includes a rotatable body (rotatable ring) and an encoder. The rotatable body and the encoder allow the physicians to rotate the insertion plane in the display by rotating the rotatable body of the orientation localizer mounted on the patient. Therefore, physicians can easily determine the insertion plane without changing their attention between operation of the images and operation of the orientation localizer. Also, the rotatable body and the encoder provide real-time update of the insertion plane in the display corresponding to the angular position of the insertion-plane indicator. Therefore, physicians can easily update the insertion plane when the need to change the planned trajectory arises.

[00130] -The medical guidance device provides the information of the insertion angle from the localized plane on the insertion plane that the physicians determine. Therefore, the physicians can use the information for accurate and quick targeting of the medical tools with the medical device by using the localized plane and the insertion plane as landmarks.

[00131] -The medical guidance system according to some embodiments includes a memory unit in the circuit box (controller) of the orientation localizer. Since the orientation localizer keeps the device information in itself instead of in the computer, the device information can be made consistent to the guidance device at a manufacturing side instead of at a user side. Therefore the device-to-image registration can be conducted with the correct device information while avoiding wrong information or missing information caused by the maintenance at the user side. Also, because the computer does not need to maintain or update the orientation localizer information, the guidance system can reduce the processing time for device-to-image registration during an intervention procedure. The guidance system can also reduce human-factor errors by users and a risk of using wrong device information for the device-to-image registration.

[00132] Moreover, the device information can include difference among individual devices, manufacturing lots and design generations without changing the computer configuration at the user side, and without the need to keep a list of device information in the computer. Therefore, the system can consistently provide high accuracy between an actual device configuration and the device information for the device-to-image registration with minimal processing time. Specifically, when the computer is reusable, and the guidance device is disposable, the system allows users and manufacturers to incorporate a variety of the guidance devices with minimal changes to the system.

[00133] In some embodiment, the orientation localizer includes a rotary scale and a rotary encoder to measure absolute angular position. By measuring absolute angular position of the rotary scale with the rotary encoder, the system does not need to ask users to perform calibration steps to establish a zero position of the rotary encoder. Therefore, the system can reduce human-factor errors about the calibration steps to conduct device- to-image registration. Also, using an absolute angular position, the system can reduce setting up steps to start using the guide device without the calibration steps and can reduce duration of the intervention.

[00134] In some embodiments, the computer obtains the design parameters of the microcontroller in the orientation localizer, and computes the coordinates of the guidance device. By assigning the computation of the coordinates of the guidance device to the computer, the system can minimize computation in the microcontroller. Therefore, the system can reduce heat generation in the guidance device, which is mounted close to the patient. Also, the system can reduce the cost and the footprint of the microcontroller with lesser computation power. The low cost is also an advantageous factor when the guidance device is made to be disposable. -Moreover, when the guidance device is powered by a battery, the system efficiently increases the device operation time by saving battery power with a low computation task in the microcontroller and high computation tasks in the computer.

[00135] -In some embodiments, the orientation localizer includes wireless communication. By having wireless communication between the guide device and the computer, the computer can locate in a different room from the room with the guidance device, i.e. the room with the patient, even if there are no physical electrical-connection ports between them. Therefore, by using the computer out of the room with patient, the physician can plan and discuss the intervention without the patient. Also, the physician frequently confirms the medical images for the intervention in out of the room with the medical imaging device like CT and MRI to minimize image degradation or to avoid unnecessary ionization to the physician. Therefore, by allowing using the computer in out of the room with the medical image device, the system can minimize change of the current workflow and minimize to add additional travel to inside of the room. Especially, the room with CT imaging device doesn't frequently equip the physical electrical -connection ports and the physical port to feed cables. Therefore, the system can become compatible to wider range of the room with the CT imaging device without any modification in the room side. Also, the system can reduce the risk of cable tangling and can make cable management easy, in particular in the surgical field.

< software implementations>

[00136] Embodiment(s) of the present disclosure can be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a 'non-transitory computer-readable storage medium') to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/ or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. An I/O interface can be used to provide

communication interfaces to input and output devices, which may include a keyboard, a display, a mouse, a touch screen, touchless interface (e.g., a gesture recognition device) a printing device, a light pen, an optical storage device, a scanner, a microphone, a camera, a drive, communication cable and a network (either wired or wireless).

< definitions >

[00137] In referring to the description, specific details are set forth in order to provide a thorough understanding of the examples disclosed. In other instances, well- known methods, procedures, components and circuits have not been described in detail as not to unnecessarily lengthen the present disclosure. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed.

[00138] The term "medical device" is a term that may include surgical and non surgical devices and those terms are intended to cover their plain and ordinary meaning, including without limitation, ablation probes, biopsy needles, scalpels, endoscopes, ultrasound wands, and the like. The term "needle" or "needle-like medical tool" refer to any rigid or non-rigid needle-like object, such as an ablation probe, biopsy needle, cannula, catheter, electro-cautery device, Bovie, stent guiding devices, and the like. The guide system and methods are not limited to be used with needle-like instruments. As long as a medical instrument can be image-guided under the principles described in the present disclosure, the guide system and methods may also be used with non-needle devices such as scalpels, forceps, cutting tools, sheers, and even lasers or laser waveguides.

[00139] It should be understood that if an element or part is referred herein as being "on", "against", "connected to", or "coupled to" another element or part, then it can be directly on, against, connected or coupled to the other element or part, or intervening elements or parts may be present. In contrast, if an element is referred to as being "directly on", "directly connected to", or "directly coupled to" another element or part, then there are no intervening elements or parts present. When used, term "and/or", may be abbreviated as "/", and it includes any and all combinations of one or more of the associated listed items, if so provided.

[00140] Spatially relative terms, such as "under" "beneath", "below", "lower", "above", "upper", "proximal", "distal", and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the various figures. It should be understood, however, that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, a relative spatial term such as "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein are to be interpreted accordingly.

Similarly, the relative spatial terms "proximal" and "distal" may also be interchangeable, where applicable.

[00141] The term "about" or "approximately" as used herein means, for example, within 10%, within 5%, or less. In some embodiments, the term "about" may mean within measurement error. In this regard, where described or claimed, all numbers may be read as if prefaced by the word "about" or "approximately," even if the term does not expressly appear. The phrase "about" or "approximately" may be used when describing magnitude and/or position to indicate that the value and/or position described is within a reasonable expected range of values and/or positions. For example, a numeric value may have a value that is +/-o.i% of the stated value (or range of values), +/-i% of the stated value (or range of values), +/-2% of the stated value (or range of values), +/-5% of the stated value (or range of values), +/-io% of the stated value (or range of values), etc. Any numerical range, if recited herein, is intended to include all sub-ranges subsumed therein.

[00142] The terms first, second, third, etc. may be used herein to describe various elements, components, regions, parts and/ or sections. It should be understood that these elements, components, regions, parts and/ or sections should not be limited by these terms. These terms have been used only to distinguish one element, component, region, part, or section from another region, part, or section. Thus, a first element, component, region, part, or section discussed below could be termed a second element, component, region, part, or section without departing from the teachings herein.

[00143] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an", "said" and "the", are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the terms "includes" and/or "including", when used in the present specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof not explicitly stated. It is further noted that some claims may be drafted to exclude any optional element; such claims may use exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements, or it may use of a "negative" limitation.

[00144] In describing example embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner.

[00145] While the present disclosure has been described with reference to exemplary embodiments, it is to be further understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest reasonable interpretation to encompass all modifications, equivalent structures and functions.