System and method for automatic control of a cranial drill

Abstract

A system for MRI-guiding of a cranial drill for drilling a burr hole into a skull of a patient in vivo. The system comprises an MRl-compatible controller configured to send actuator commands and an MRI-compatible cranial drill system adapted to be secured to, or proximate to, the head of the patient. The cranial drill system includes a pressure sensor and is adapted to receive the actuator commands and send position data and force feedback from the pressure sensor to the controller. A fiber optic cable is connected between the controller and navigation software. The navigation software is configured for transmitting scanner control signals to the MRI scanner and receiving images generated by the MRI scanner for transmission to a display output for receiving electrical signals and for displaying corresponding images. The navigation software is adapted to receive commands based on the images.

Description

[0001] SYSTEM AND METHOD FOR AUTOMATIC CONTROL

[0002] OF A CRANIAL DRILL

[0003] Cross-References

[0004] This application claims the benefit of U.S. Provisional patent application no. 63 / 690,722, filed September 4, 2024, entitled System and Method for Automatic Control of a Cranial Drill, the contents of which are incorporated herein in their entirety.

[0005] Background

[0006] This application relates to a cranial drill for making openings in the skull and, more particularly, a system and method for automatic control of the cranial drill for positioning and operating the drill bit.

[0007] The creation of openings in the skull, such as burr holes, is a critical and important step for most of therapeutic and diagnostic interventions if the brain region, including delivery of treatment / therapy. This includes stereotactic neurosurgery procedures, where typically an instrument is delivered through a hole in the skull to a specific target in the brain. The precision and safety of creating that opening is paramount to maximizing patient outcomes and minimizing negative side effects.

[0008] Burr hole creation, which for the purpose of this application is the creation of a hole in bone such as the skull, is a critical step for many different therapeutic procedures which require a clear path to deliver treatment or perform diagnostics into underlying tissue, such as the brain. A cranial drill is the common tool that surgeons use to create the burr hole. The performance of current cranial drills highly depends on the performance of the surgeon instead of the tool itself. There are hundreds of failed cases as the cranial drilling process failed or the surgeon happened to drill through the meningitis in which case the brain is damaged. The FDA has already sent out an alert that perforators which are commonly used might fail under certain conditions. There are thousands of people each year undergoing burr hole creation as a part of surgeries including for deep brain stimulation (DBS) or other neuro stimulators, brain-computer interface (BC1) device, ablation for cancer or functional targets, evacuation of hematomas or draining other fluids such as CSF, targeted biopsy sample retrieval, stereoelectroencephalography (SEEG) electrode delivery, catheter-based imaging or sensing, local injection of therapeutics, and controlling localized release of therapeutics. All of these procedures require precise, safe creation of an opening into the skull to allow the instrument to pass to the intended target while avoiding damage to critical structures.

[0009] For the foregoing reasons, there is a need for a more reliable and accurate cranial drill and system, including control of the cranial drill for creating burr holes and improving outcomes. Ideally, the new system and method will minimize surgeon skill or other human intervention as a critical factor in safe and accurate drill placement and use.

[0010] Summary

[0011] An MRI-guided interventional system is provided for guiding placement of a drill bit of a cranial drill for drilling a burr hole into a skull of a patient in vivo. The cranial drill bit placement system comprises an MRI-compatible controller configured to send actuator commands. An MRI-compatible cranial drill system is adapted to be secured to, or proximate to, the head of the patient. The cranial drill system includes a pressure sensor, wherein the cranial drill system is adapted to receive the actuator commands and send position data and force feedback from the pressure sensor to the controller. A fiber optic cable is connected between the controller and navigation software. The navigation software is configured for transmitting scanner control signals to the MRI scanner and receiving images generated by the MRI scanner for transmission to a display output for receiving electrical signals and displaying corresponding images. The navigation software is adapted to receive commands based on the images.

[0012] The MRI-guided interventional system further comprises a control console, wherein the fiber optic cable is connected between the controller and the control console. The controller comprises the navigation software and provides images to the display output.

[0013] The controller may comprise a robot controller and a drill controller, and further comprise a robot assistive device for receiving and sending actuator commands from and to the controller.

[0014] The fiber optic cable extends through a barrier of an MRI suite between a control room and an MRI scanner room. The control console is in the control room. The controller is in the MRI scanner room.

[0015] A method is also provided for MRl-guided automated placement of a cranial drill bit for drilling a burr hole in a skull of a patient in vivo. The cranial drill bit placement method comprises the steps of providing an MRI-compatible cranial drill system including a pressure sensor. An MRI scanner is used for scanning at least a skull of the patient. A controller is provided along with a control console for communicating with the controller. Commands are sent and force feedback received from the cranial drill system for a surgical procedure on the patient. Further steps comprise providing a robot for moving the cranial drill system, sending commands from the controller to the robot, and receiving controller feedback from the robot for moving the cranial drill bit of the cranial drill system for performing a surgical procedure on the patient. Images may be provided from the controller, and emergency commands issued to the controller.

[0016] In another embodiment, the MRI-guided interventional system further comprises a cranial drill assembly, and a shell for housing the cranial drill assembly, the shell having an opening for passing the drill bit. The MRI-compatible cranial drill assembly comprises an axial translation subsystem movable relative to the shell for advancing and retracting the drill bit through the opening along the axis of the bit. A bit driver system and a an optical limit switch are also mounted on the axial translation subsystem. The optical limit switch comprises a sensory base, and a moving flag member. The axial translation subsystem comprises a rotary motor, at least one lead screw driven by the rotary motor, and a movable platform integral with the lead screw, the movable platform constrained to only linear movement such that actuation of the rotary motor drives the platform linearly in one direction or an opposite direction. In one embodiment, the rotary motor is a piezoelectrically actuated motor. The axial translation subsystem may comprise a second rotary motor for driving the drill bit.

[0017] An MRI-guided surgical method for using a cranial drill system for automatically controlling the drill bit is provided. The cranial drill system control method comprises the steps of mounting a cranial drill system to, or proximate, to a skull of the patient. The patient is preoperatively scanned with the MRI scanner for obtaining a medical image of a target area. A surgical process is planned, including a trajectory of the drill bit based on the images generated by the scan. The position of the cranial drill system and trajectory of the drill bit are verified with a second scanning of the patient for obtaining a medical image of the patient and the cranial drill system. The rotation of the drill bit begins. Real time scanning continues during the procedure with a focus on the target area for a view of the advancing drill bit. The drill bit is automatically advanced to a desired location along a planned trajectory based on tracking of the drill bit. Real time force sensing of the drilling process occurs. Rotation of the drill bit stops upon significant reduction in sensed force. The drill bit is retracted leaving a burr hole in the skull of the patient.

[0018] In one embodiment, the step of mounting the cranial system comprises mounting the cranial drill system to a robot assistive device, and the step of planning a surgical process based on the images generated by the scanning comprises sending the image signals to the robot for moving the cranial drill system to the targeted region.

[0019] Navigation software may be provided for determining if the target area is penetrated by the drill bit.

[0020] Brief Description of the Drawings

[0021] For a more complete understanding of the system and method for automatic control of a cranial drill, reference should now be had to the embodiments shown in the accompanying drawings and described below. In the drawings:

[0022] Fig.l is a schematic illustration depicting one embodiment of a system architecture with a cranial drill system and a controller inside an MRI scanner room and a control console and operator outside the MRI scanner room.

[0023] Fig.2 is a schematic illustration depicting the embodiment of the system architecture with the cranial drill system as shown in Fig. 1 with an operator another operator outside the scanner room.

[0024] Fig.3 is a schematic illustration depicting the embodiment of the system architecture with the cranial drill system as shown in Fig. 1 including an assistive robot device and the corresponding controller inside the MRI scanner room.

[0025] Fig.4 is a schematic illustration depicting the embodiment of the system architecture with the cranial drill system as shown in Fig. 1 including an assistive robot device and corresponding controlleran with a human operator inside the MRI scanner room and a control console and another human operator outside the scanner room.

[0026] Fig. 5A is a schematic illustration depicting one embodiment of a teleoperation framework of acranial drill system only one human operator operating outside an MRI scanner room.

[0027] Fig. 5B is a schematic illustration depicting the embodiment of a teleoperation framework of a cranial drill system as shown in Fig. 5A including an assistive robot and controller.

[0028] Fig. 6A is a schematic illustration depicting one embodiment of a teleoperation framework of a cranial drill system with one human operator in control.

[0029] Fig. 6B is a schematic illustration depicting one embodiment of a teleoperation framework of the cranial drill system as shown in Fig. 6A with a second human operator.

[0030] Fig.7 is a bottom perspective view of an entire cranial drill system with a drill bit extending outwardly of a shell.

[0031] Fig.8 is a front perspective view of an embodiment of the mechanical structure of the cranial drill when a side shell is removed and major subsystems in place.

[0032] Fig.9 is a front perspective view of one embodiment of a limit switch.

[0033] Fig.10 is a front perspective view of one embodiment of mechanical structure of a vertical translation subsystem of the cranial drill system.

[0034] Fig.11 is an exploded perspective view of one embodiment of mechanical structure of a rotational subsystem for driving a drill bit of the cranial drill system.

[0035] Fig.12 is a perspective view of one embodiment of mechanical structure of a skull clamp with pressure sensor embedded.

[0036] Fig.13 is a block diagram of an embodiment of a method of use for the cranial drill system directly mounted onto the patient’s head.

[0037] Fig.14 is a block diagram of an embodiment of a method of use for the drill system mounted onto an assistive robot.

[0038] Fig.15 is a side elevation view of an embodiment of a method for using the cranial drill system directly mounted onto a human skull using a skull clamp when inside an MRI scanner.

[0039] Fig.16A is a perspective view of an embodiment of a method of use when the cranial drill system is mounted on an assistive robot with the human skull inside an MRI scanner.

[0040] Fig.16B is a perspective view of another embodiment of a method of use when the cranial drill system is mounted on an assistive robot with the human skull inside an MRI scanner.

[0041] Fig. 17 is a front perspective view of an embodiment of the mechanical system design of a cranial drill system with a drill bit is extended out from a shell.

[0042] Fig.18 is a a perspective view of an embodiment of mechanical structure of a cranial drill when a curved panel and a side panel are removed with major subsystems in place.

[0043] Description

[0044] Certain terminology is used herein for convenience only and is not to be taken as limiting. For example, words such as "upper," "lower," "left," "right," "horizontal," "vertical," "upward," "downward," “top” and “bottom” merely describe the configurations shown in the drawings. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. The words “interior” and “exterior” refer to directions toward and away from, respectively, the geometric center of the core and designated parts thereof. The terminology includes the words specifically mentioned above, derivatives thereof and words of similar import.

[0045] In one embodiment, a cranial drill system consists of a mechanical structure, a control box, a navigation software, a communication structure, and a dedicated workflow for corresponding setup. The mechanical structure can be enclosed within a shell or other enclosure. It may be attached to various types of assistive devices, including fixed to the skull, manually movable, and robotically actuated, and is not limited to the embodiment presented. The cranial drill system can work with various types of drill bits, including but not limited to, standard twisting drill bits, cranial drill bits, perforators and the like.

[0046] The present invention is not limited in the type if instrument that it can hold. One embodiment of the drill system allows interchanging multiple instruments including, but not limited to, drills. The drill system may also be used to support the insertion and / or rotation of other instruments including, but not limited to, ablation devices, biopsy needles, injection catheters, neurostimulator leads, and evacuation cannulas. In one embodiment of the present invention, the drill system controls insertion and rotation of a drill to create a burr hole in the skull, and then the drill bit is exchanged for another therapeutic or diagnostic instrument for placement into the brain through the crated burr hole. This enables rapid, precise, and safe delivery of instruments, such as those previously noted in the application, through the hole created by the drill system. In one example, the drill system creates a burr hole and then is used to control the depth and rotation angle of a directional ablation applicator placed through that burr hole.

[0047] The cranial drill system is compatible with various types of actuators including, but not limited to, rotary motors and linear motors. In one embodiment shown and described herein, two rotary motors are deployed to provide a source of motion.

[0048] An embodiment of the present invention is designed to operate within an MRI environment, and is actuated using piezoelectric actuators. In other embodiments, brushed or brushless DC motors, pneumatics, hydraulics, or other actuation means may be utilized. The drill system may operate within the room of a traditional diagnostic MRI room or a specialized interventional MRI suite, and may be operated within the bore of the MRI scanner during imaging without material degradation of image quality. The drill system may be used with closed bore high field scanners such as, but not limited to, 1.5 tesla, 3.0 tesla, and 7 tesla. It may also be used in lower field strength scanners such as 0.5 tesla and ultra low field scanner. The drill system may also be used in a traditional operating room (OR) setting with or without supplemental medical imaging. The drill system can also be utilized with intraoperative computer tomography (CT) imaging. The proposed embodiments are intended as examples and the invention is not limited to only the specific embodiments described. One skilled in the art will recognize that aspects of the disclosed embodiments may be combined in other ways.

[0049] Referring now to the drawings, wherein like reference numerals designate corresponding or similar elements throughout the several views, an embodiment of a cranial drill system and method for automatic control of a cranial drill is shown in FIG. 1 and generally designated at 100. The system setup comprises a controller 101, which includes a sensor interface 106, and a fiber-optic interface 102 located inside a magnetic resonance imaging (MRI) scanner room. While shown in an MRI environment, this system is not limited to only operating within an MRI environment. The controller 101 sends actuator commands 105 to a cranial drill system, unit or subsystem 114, and the cranial drill system 114 sends position feedback 110 to the controller 101. The actuator commands 105 may be motor drive signals to control motors within the cranial drill. In one embodiment, they represent waveforms intended to drive piezoelectric motors in the cranial drill system (114). A sensor 112 integrated in the cranial drill system 114 provides force feedback 111 to the sensor interface 106 inside the controller 101. Further, an actuation driver system within the controller 101 that is providing the actuation signals 105 may also provide feedback related to the force applied by the drill system 114.

[0050] In an embodiment, the sensor 112 is a single axis pressure or force sensor. In other embodiments, the sensor 112 may comprise sensing of force, pressure, vibration, displacement, strain, or other means in one or more axes. The sensing may be done via electrical means, optical means, pneumatic means, hydraulic means, or other techniques for detecting interactions with the cranial drill system. In another embodiment, interaction force, torque, pressure sensing is achieved through monitoring the control signals to the actuator. In one configuration, electrical current to drive motors is used to assess the interaction load on the motor, and in turn, the drill. In another configuration, the resonant frequency, electrical current, or other characteristics of a piezoelectric motor being used to rotate the drill and or insert the drill along its axis are able to assess the interaction force, torque, or pressure on the tip of the drill. These noted sensor types or means are described in this embodiment, but apply to all other described embodiments of the system and sensor 112 in this description.

[0051] The controller 101 communicates with a navigation software 103 through the fiberoptic interface 102 with an optical fiber 117 which goes through an MRI patch panel 115, also referred to as a penetration panel. The navigation software 103 sends scanner control commands 104 to an MRI interface 109, such as the console computer of the MRI scanner, and receives images 108 back from the MRI interface 109. Upon receiving the images 108, the navigation software 103 visualizes 113 to a human operator 116. The human operator 116 sends commands 107 through navigation software 103 to the controller 101 inside the scanner room. It should be noted that, while described embodiments show configurations wherein the cranial drill system operates within an MRI scanner room, this invention is not constrained only to that environment. Embodiments of the cranial drill system may be used in traditional operating rooms or other surgical spaces, and the system may integrate with other imaging modalities including x-ray, computer tomography, positron emission tomography, ultrasound, photoacoustic imaging, optical imaging, or other means. This approach is also not restricted to only cranial application in the head of a human patient. The present invention may be used in other anatomy and for other clinical applications all over the body, such as spinal or orthopedic applications. The present invention may be used in human clinical procedures, on cadavers, and in veterinary practice. The present invention may also be used in non-medical applications for precision control of drilling operations.

[0052] Fig. 2 represents another embodiment of a cranial drill system setup for automatic control of a cranial drill and is generally designated at 200. The cranial drill system 200 comprises a controller 201 which includes a sensor interface 202, a navigation software 203, and a fiber-optic interface 204 located inside an MRI scanner room. The controller 201 sends actuator commands 209 to a cranial drill system 218, and the cranial drill system 218 sends position feedback 215 to the controller 201. A pressure sensor 219 integrated in the cranial drill system 218 provides force feedback 210 to the sensor interface 202 inside the controller 201. The controller 201 communicates with a control console 206 through the fiber-optic interface 204 with an optical fiber 211 which goes through an MRI patch panel 221. The control console 206 sends scanner control commands 207 to an MRI interface 208 and receives images 213 back from the MRI interface 208. Upon receiving the images 213, the control console 206 visualizes 217 to a first human operator 1 222. The human operator 1 222 sends commands 212 through control console 206 with images 213 to the navigation system 203 inside the scanner room. The navigation software 203 illustrates images 216 to a second human operator 2 220. The second human operator 2 220 sends command 214 to the controller 201 in case of emergency.

[0053] Fig. 3 represents yet another embodiment of a cranial drill system setup, wherein the drill system is coupled to an actuated assistive device, such as a robot, for automatic control of a cranial drill and is generally designated at 300. The drill system 300 comprises a controller box 301 which contains a controller for an assistive robot device 302 and a controller for a drill system 303. The controllers for the drill system and the assistive robot device may be coupled within the same controller box 301 or as separate distinct units. The controller box also includes an interface for a pressure and / or force sensor, which in one embodiment is a fiber-optic interface 304. The controller box 301 is located inside an MRI scanner room. The controller for assistive robot device 302 sends actuator commands 312 to an assistive robot device 318, and the assistive robot device 318 sends position feedback 308 to the assistive robot controller 302. A controller for a cranial drill system 303 sends actuator commands 315 to a cranial drill system 319. One or more pressure sensors 316 (pressure and / or force sensors may be used and either may be used in the embodiment described in this disclosure, further they may reflect readings along one axis or multiple axes) integrated in the cranial drill unit 319 provides force feedback (pressure, force, and / or other tactile feedback may be used and either may be used in the embodiment described in this disclosure, and that feedback may be based on actual current or time- averaged or otherwise filtered values, changes in values (e.g. derivatives), power spectrum such as measuring variation or vibration, or other measure generated at least in part from the signals from the sensors) to a sensor interface 309 inside the cranial drill controller 303. The controller box 301 communicates with the navigation software 305 through the fiber-optic interface 304 with an optical fiber 310 which goes through an MRI patch panel 320. The navigation software 305 sends scanner control commands 306 to an MRI interface 307 and receives images 311 back from the MRI interface 307. Upon receiving the images 311, the navigation software 305 visualizes 317 to a human operator 321. The human operator 321 sends commands 313 through the navigation software 305 to the controller box 301 inside the scanner room.

[0054] Fig.4 represents still another embodiment of a cranial drill system setup for automatic control of a cranial drill and is generally designated at 400. The drill system 400 comprises a controller box 401 which contains a controller for assistive robot 402, a controller for the cranial drill system 403, a navigation software 404, and a fiber-optic interface 405. The controller box 401 is located inside an MRI scanner room. The controller for assistive robot 402 sends actuator commands 409 to an assistive robot device 420, and the assistive robot device 420 sends position feedback 416 to the assistive robot controller 402. The controller for the cranial drill system 403 sends actuator commands 410 to a cranial drill system 421. A pressure sensor 422 integrated in the cranial drill system 421 provides force feedback 417 to a sensor interface 411 inside the cranial drill controller 403. The controller 401 communicates with the control console 406 through the fiber-optic interface 405 with an optical fiber 413 which goes through an MRI patch panel 424. The control console 406 sends scanner control commands 407 to an MRI interface 408 and receives images 414 back from the MRI interface 408. Upon receiving the images 414, the control console 406 visualizes 419 to a first human operator 1 425. The human operator 1 425 sends commands 415 through the control console 406 with the images 414 to the controller 401 inside the scanner room. The navigation software 404 illustrates the images 418 to a second human operator 2 423. The human operator 2423 sends command 412 to the controller 401 in case of emergency.

[0055] Fig.5A represents one embodiment of the system setup for automatic control of a cranial drill and is generally designated at 500. The system comprises a human operator 501 who controls a control console 502, which communicates with a controller 503. The controller 503 sends commands and receives feedback from a cranial drill system 504, which is applied in a procedure onto a patient 505. Fig.5B represents a human operator 506 controlling a control console 507, which communicates with a controller 508. The controller 508 sends commands and receives feedback from an assistive robot device 509 and moves a cranial drill system 510. With commands from the controller 508, the cranial drill system 510 applies a procedure onto a patient 511. A similar approach is utilized in one embodiment where the drill is exchanged for another instrument and that instrument is controlled by the assistive robot device 509. In one embodiment, force feedback is utilized for assessing the tissue interaction force of the instrument as it is delivered into the tissue through the created burr hole, such as an injection cannula, biopsy needle, ablation applicator, or other instrument such as those described earlier.

[0056] FIG. 6A represents one embodiment of the system control setup for automatic control of a cranial drill and is generally designated at 600. The system comprises a first human operator 1 601 controlling a control console 602, which communicates with a controller 603. The controller 603 sends commands and receives feedback from a cranial drill system 604, which is applied in a procedure onto a patient 605. A second human operator 2 606 receives image illustrations from the controller 603 and sends emergency commands to the controller 603. Fig.6B represents one embodiment of the system control setup where a first human operator 1 607 controls the control console 608, which communicates with the controller 609. The controller 609 sends commands and receives feedback from an assistive robot device 612 and moves the cranial drill system 610. With the commands from the controller 609, the cranial drill system applies a procedure onto the patient 611. The second human operator 2 613 receives image illustrations from controller 609 and sends emergency commands to the controller 609.

[0057] Fig.7 shows one representative embodiment of a shell housing a cranial drill system and is generally designated at 700. The shell 700 comprises an outer shell 701 for encapsulating the mechanical structure of the cranial drill system. A hole 704 at a bottom side of the outer shell 701 allows a drill bit 703 to protrude through. A side 702 of the shell 700 is removable to allow the opening and sterilizing of the cranial drill system. In one embodiment, the entire cranial drill system is configured as a disposable single-patient sterile kit, and may be configured with pre-installed drill bits. As noted, in one configuration the drill bit may be swapped for a different surgical instrument so as to perform an intervention through the drilled hole.

[0058] Fig.8 shows another embodiment of a cranial drill system with a shell and is generally designated at 800. The shell comprises an outer shell 801 containing an axial (ie, along the drill or instrument axis, vertical as shown) translation subsystem 802, a drill bit driving subsystem 803, an optical limit switch subsystem 805, and a burr hole drill bit 804. The axial translation subsystem 802 moves within the outer shell 801, providing feeding motion to the drill bit driving subsystem 803. A travel limit sensor, such as the optical limit switch subsystem 805 is mounted on the vertical translation subsystem 802 to calibrate the translational motion of the drill bit 804. The combination of the axial translation subsystem 802 and the drill bit driving subsystem 803 provides the full 2-degrees of freedom (DOF) motion of the drill bit 804. The shell 801 may have an opening though its top and bottom, and the drill bit may be exchanged for another surgical instrument which may utilize the rotation and or axial translation to perform a diagnostic or therapeutic intervention through the drilled hole. In one example, the system creates a drill hole, and a directional ablation applicator is then placed into the 2- DOF cranial drilling unit so that the direction may be controlled by the instrument rotation, and the depth may be controlled by the axial translation (insertion and / or retraction). In a further embodiment, the drilling unit may be used for actuated retraction or pull-back of an instrument along the axial translation.

[0059] Fig.9 shows a sensory base 901 carried by the optical limit switch subsystem 805. The sensory base 901 includes a moving flag 902. The sensory base 901 is considered as “triggered” when the tip of the moving flag 902 reaches the center of the U-shape and blocks the IR in between. The optical limit switch subsystem may use sensors configured for a thru-beam or reflective optical sensing approaches. Other types of proximity and limit switch sensors may also be used. Alternatively, stall detection may be utilized wherein the system identifies when the actuation stops moving at the end of travel by monitoring the position feedback.

[0060] Fig.10 shows an embodiment of an axial (ie, vertical as shown) translation subsystem for providing the linear motion. The vertical translation subsystem comprises a rotary motor 1021 mounted on to a mount plate 1020. The rotary motor 1021 actuates a timing belt pulley 1013, and the motion of the pulley is transferred through a timing belt 1003 to another second timing belt pulley 1004. The second timing belt pulley 1004 drives a lead screw 1005. The lead screw 1005 is coupled with a lead screw nut 1008 is mounted on a moving platform 1006 with four sliders 1007, 1024 and another second lead screw nut 1023. The sliders 1007,1024 move linearly with respect to two rod guides 1001,1022, which are mounted to the outer shell with top mounts 1002 and bottom mounts 1009, 1025. The rotation of the lead screw 1005 drives a timing belt pulley 1011, and the motion is transferred to another second timing belt pulley 1016 on the other side of the vertical translation subsystem through a timing belt 1015. The timing belt 1015 drives a lead screw 1018 which couples with the second lead screw nut 1023. The motion of the two lead screw mechanisms 1005, 1008, 1018, 1022 and the rod guides 1001, 1007, 1022, 1024 provides linear vertical translation to the moving platform 1006. In one configuration for use with the various embodiments as described herein, the rotary motors are piezoelectrically actuated motors. In other configurations, other motor types may be used including traditional electric motors, pneumatic motors, hydraulic motors, or other means of creating rotary motion. In another configuration, linear actuators may be used to directly create linear motion. The linear actuators may be linear piezoelectric motors, or other actuation approaches as previously noted.

[0061] Fig.11 shows an embodiment of a rotary motor 1102 which may be mounted onto the moving platform 1101. The rotary motor 1102 drives a timing belt pulley 1106, which motion is transferred to another timing belt pulley 1108 through a timing belt 1107. The timing belt pulley 1108 is connected to a collet adapter 1112 with first and second bearings 1109,1110 in between to reduce the friction and keep proper spacing. A hollow pressure or force sensor 1111 is located between the collet adapter 1112 and the second bearing 1110. A collet 1103 and a cap 1104 are used to hold and align a drill bit 1105. As previously noted, drill bit 1105 may be exchanged for an alternative instrument, such as one intended for a therapeutic or diagnostic intervention through the hole drilled by drill bit 1105.

[0062] Fig.12 shows one embodiment of a skull clamp 1201 integrated with a strain gauge or pressure gauge 1202. As the drill presses down onto the skull, deformation of the skull clamp 1201 is created at the joint which will be detected by the strain gauge or pressure gauge.

[0063] Fig.13 shows a flow chart presenting one embodiment of a method for automatic control of a cranial drill. As a surgical procedure starts 1301, a preoperative medical imaging scan 1302 of a targeted area will be scanned. A preoperative surgical planning process 1303 takes place based on the result from the preoperative scan 1302. According to the surgical plan generated in the surgical planning process 1303, a device with a cranial drill system will be mounted 1304. A verification medical imaging scan 1305 will be taken to confirm the position of the device 1306. If the result from the verification scan 1305 does not match expectations, the cranial drill device 1304 will be mounted again or the position adjusted until there is a match. This alignment process may be performed with the assistive robot manipulator device, through a manual adjustment, or by other means. Once the device 1306 is in the intended correct position corresponding to the surgical plan, the drill bit starts to rotate 1307 and live, real-time medical imaging scan 1308 starts simultaneously. A force sensor tracks the live real-time measurement of interaction force 1309, filters out the noise on the sensor signal, and outputs a smooth signal to be used for data acquisition and analysis. As the drill bit presses down along its axis towards the target 1310, the force sensor 1309 will receive a constant high force value and images from the real-time scan 1308 will be processed, with a focus at the target region and a mask that covers redundant image. A navigation software will process the data, and check if the target gets penetrated 1311. If not, another real-time scan will take place 1308 with the drill bit continuing to press down along its axis 1310. Meanwhile, if there is a significant reduction in the sensed interaction force 1312 from the force sensor 1309, the system identifies puncture and the drill bit will be retracted to its shell 1313 to prevent damage to underlying tissue. The procedure ends 1314 after the retraction of the drill bit 1313.

[0064] Fig.14 represents another embodiment of a flow chart for a method for automatic control of a cranial drill including an assistive robot device. As the procedure starts 1401, a preoperative scan 1402 of a targeted area or region is scanned. A pre-operative planning 1403 takes place based on the result from the preoperative scan 1402. According to the planning 1403, the result will be sent to a controller for an assistive robot device that is mechanically coupled to the cranial drill system mounted 1404. The assistive robot device will then move with the coupled drill system to align with the targeted region 1405. A verification scan 1406 will be taken to confirm the position (which includes the full pose including linear position and angular orientation) of the cranial drill device 1407. If the result from the verification scan 1406 does not match expectations, the device will be moved by the assistive robot device 1405 again until it matches. Once the cranial drill device is in correct position, the drill bit starts to rotate 1408 and real-time scanning 1409 starts simultaneously. A force sensor tracks the live real-time measurement of interaction force 1410, filters out the noise, and outputs a smooth line for data acquaintance. As the drill bit is actuated linearly along its axis and is continues pressing into the target tissue 1411, the force sensor will receive a substantially constant high value 1410, and images from real-time scanning 1409 will be processed, with a focus at the target region and a mask that covers redundant imaging. A navigation software will process the data and check if the target is penetrated 1412. This is intended as a visual means of identifying depth and break-through of the target structure (e.g. cranial bone) based on live or iteratively updated medical imaging of internal anatomy that can be performed via MRI, CT, or other means. If the drill has not yet penetrated, real-time scans will continue to take place 1409 with the drill bit continuing to rotate and press into the target tissue 1411. At the same time as the imagebased monitoring, there is also force / pressure sensor-based monitoring of the drilling pressure. If there is a significant reading drop (1413) from the force sensor, indicating break-through, the insertion axis of the assistive robot device will be retracted 1414 to clear the path. The drilling operation of the procedure reaches an end 1415 after the retraction of the drill bit 1414. The drill bit may then be swapped for another instrument to deliver through the hole, or another target may identified to drill another hole.

[0065] Fig.15 shows one embodiment of a system for automatic control of a cranial drill wherein the drill system is mounted on a patient or mechanically coupled to a skull clamp mounted onto the patient 1501. The patient 1501 is lying on a bed inside a MRI scanner 1502. A cranial drill system 1503 is mounted on a skull clamp 1504 or other alignment device rigidly attached to the skull 1504. The skull clamp 1504 is mounted on the skull of the patient 1501 with the guidance of the MRI scanner 1502 to navigate the cranial drill system 1503 to an ideal position to start the drilling process. The present invention comprises the configuration wherein the cranial drill system 1503 is attached directly to the skull (or other bony anatomy), the configuration wherein the cranial drill system is attached to a robotic manipulator or other active or actuated device, the configuration wherein the cranial drill system is handheld, and the configuration wherein the cranial drill system is coupled to a passive frame or other fixture, such as a standard 4-point stereotactic frame or a traditional 3-point head clamp. As previously noted, the invention is not limited to only MRI and the noted embodiments in this disclosure may be used in an MRI room, a CT room, an operating room, or other facility.

[0066] Fig.l6A shows an embodiment of a system for automatic control of a cranial drill wherein a cranial drill system is mechanically coupled on to an assistive robot device. A patient 1601 is lying on the bed inside a MRI scanner 1602. A cranial drill system 1603 is mounted on an assistive robot device 1604. The assistive robot device 1604 navigates the cranial drill system 1603 to an ideal position to start drilling process on the skull of the patient 1601 with the guidance of the MRI scanner 1602. Fig.l6B represents one embodiment where a cranial drill unit 1607 is mechanically coupled to an assistive robot device 1608. A patient 1605 is lying on the bed or table 1618 inside an MR1 scanner 1606 with their head position inside the tubular bore 1610 of the MRI scanner, near the isocenter of the MRI scanner. The patient’s 1605 skull 1614 is mechanically coupled into a head fixation system 1612, that is also mechanically coupled with the assistive robot device 1612 and the MRI scanner bed 1618. The assistive robot device positions the cranial drill 1607 to the defined position and orientation with respect to the patient prior to starting the drilling process on the skull 1614 of the patient 1605, with the guidance of image feedback from the MRI scanner 1606. The instrument 1616 is mechanically coupled to and manipulated by the cranial drill 1607. In one configuration, the instrument 1616 is a drill bit, burr, or other cutting instrument for the purpose of cutting an opening into the patient’s skull 1614. The instrument 1616 may be exchangeable for other instrumentation including, but not limited to, cannulas, needles, neurostimulation leads, ablation applicators, and the like. The instrument 1616 then may be manipulated in rotation and translation motion using the same cranial drill mechanism 1607. It should be noted that, while shown inside the bore 1610 of the MRI scanner, this system is configured to operate anywhere in an MRI room, or also may be used inside a CT room (either inside or outside the bore) or in an operating room (with or without medical imaging). In one embodiment, a CT scanner is utilized instead of the MRI for imaging the patient and the instrument. For the purpose of this disclosure, a CT scanner comprises a traditional computed tomography scanner, a cone beam CT system (CBCT), and O-arm type intraoperative CT scanner, or other tomographic imaging system based on x-rays. While the described system is performing cranial drilling, it should be appreciated that the present invention may be used in other anatomy, including but not limited to, cranial, spinal, abdominal, thoracic, pelvic, and limb / extremity procedures. In one embodiment, the approach described for cranial interventions is utilized for spinal interventions for drilling vertebrae.

[0067] Fig.17 shows one embodiment, wherein an outer shell or enclosure comprises of a top panel 1701, a back panel 1702, a bottom panel 1703, a side panel 1706, and a curved panel 1707 which encapsulate the mechanical structure of the cranial drill system with a hole at the bottom panel to allow a drill shaft 1708 to protrude through. The encapsulation is secured with a set of mounting hardware 1704, 1705. A drill bit 1709 is attached to the drill shaft, which may also be exchanged for an alternate instrument. A curved panel 1707 is to allow the opening and sterilizing of the cranial drill system. In one embodiment, the cranial drill is configured as a disposable sterile kit, with preinstalled drill bits in different sizes.

[0068] Fig.18 shows another embodiment of the mechanical structure of the drill system, wherein two major subsystems are implemented to provide the axial (vertical as shown) translation and rotational motion to a drill bit 1816. A worm gear set 1810 is attached to a motor 1809 to translate motion to a lead screw 1811. The rotation of the lead screw translates into linear motion with the coupling of a lead screw nut 1808 which drives a moving platform 1805. Two linear guide rails 1803 are attached to the back panel and the side panel, respectively, coupling with linear slides 1813 on the moving platform to regulate motion. A linear encoder stripe 1807 is attached to the back panel, wherein an encoder reader 1806 that mounted on the moving platform tracks the linear movement of drill bit. A motor 1804 is mounted on the moving platform, with a timing belt pulley 1802 attached and translating motion to another pulley 1815 through a belt 1801, which drives the drill bit. A force sensor 1812 is attached on the back of the drill bit, which contacts by a small fixture 1814 to track the thrust force of the drill bit. The force sensor 1812 in one embodiment is a single-axis load cell made on non-ferrous components. In another embodiment the force sensor 1812 is an optical sensor such as one utilizing Fabry-Perot interferometry (FPI) or Fiber Bragg Grating (FBG). The feedback from the force (also referred to as pressure) sensor may be utilized to assess penetration of the drill bit and may also be used to provide haptic feedback for the drill and / or other instruments.

[0069] The benefits of the system and method for automatic control of a cranial drill, as described herein, include reducing the complexity for the procedure. The typical procedure requires the surgeons to move the patient out from the MRI scan room to perform the drilling process. The movement of the bed will lead to the loss of the landmark of the MRI scanner and the associated coordinate system. The procedure of moving the patient from the MRI scanner room to an operation room and drilling the burr hole with a non-MRI-compatible cranial drill will take more than 30 minutes. With a powered MRI-compatible drill, it would require roughly 15 minutes to set up the proper tools and pneumatic connectors, and more than 1 hour to detach the tool and process with aseptic procedures. A manual MRI-compatible drill has limitations related to its stability, convenience, and accuracy due to awkward means of supporting and maintaining alignment while drilling. One embodiment of the present cranial drill system is that it may only take 10 minutes to set up and can be immediately disposed of after the procedure. The present invention allows safe, precise, consistent, and rapid drilling of holes in the skull for stereotactic instrument delivery, as well as other applications. For cases with multiple holes required, the benefits become more significant by increasing the speed while also improving safety, accuracy and consistency. Procedures such as deep brain stimulation typically require 2 burr holes, many intracranial drug delivery cases require 6-10 injection sites, and SEEG often has 10-20 electrodes placed through unique holes. The present invention can drill the holes, and may also be used to screw in guide / fixation bolts and deliver instruments through the holes.

[0070] In addition to saving time, the present system and method for automatic control of a cranial drill is imaged-guided and semi- automatic. The typical procedure only uses a set of pre-op scan images, and the rest of the procedure is all up to the surgeon. Image-guided processes can certainly increase the accuracy of the burr hole creation and avoid misalignment. Also, force which is applied to the drill system is normally quite sensitive to successful use. The force feedback system as described herein provides a reading from an electronic sensor which is much more accurate than human feelings, especially when the human is holding a handle and pressing. Note that in this disclosure, both pressure and force are used and both refer to the loading of the instrument from interactions with the tissue.

[0071] There is a need and a hole in the market for an MRI-guided cranial drill system providing a quantitative reading as feedback. One embodiment of the present system is a single-patient disposable drilling unit so that it doesn’t require aseptic processing or resterilization for reuse. In one embodiment, components used are MRI-compatible (i.e. they are compatible with operating the the environment in and around an MRI scanner) and may also be used under most environments. The present inventions is not limited to only MRI-guided procedures nor to only cranial interventions. The technique of image-guided drilling coupled with interaction force sensing system is beneficial and unique. The use case of this technique includes but not limited to burr hole creation, needle-based intervention, implants, and other drilling operations. Conventional cranial drills do not provide a quantitative readings as feedback. Currently available products can be MRI- conditional, however cannot function as in-situ nor image-guided. Moreover, the entire cranial drill system can be disposable so does not require aseptic or re-sterilization for reuse. Other conventional motorized systems are mostly non-disposable, which requires additional clean-up after use. In fact, components that are MRI-compatible can be used under most environments. Overall, use of the image-guided drill system is beneficial and includes, but is not limited to burr hole creation, needle intervention, implant, and mine drilling.

[0072] An electric- powered semi-automatic cranial drill system, that is compatible with operating within the bore of a magnetic resonance imaging (MRI) system during imaging, is provided that can be used with image guidance and / or force feedback for the cranial drilling process to precisely, consistently, and safely create the opening in the skull. The new cranial drill system is much more efficient compared with currently available cranial drill systems and also provides for improved safety and precision. The present invention may be used in any anatomy where precise and safe drilling of hard tissue such as bone is required, including, but not limited to, neurosurgical procedures. It should be understood, that while embodiments may be described for one anatomy such as cranial drilling, the present invention is not limited to only that anatomy and also applies to other bony anatomy including, but not limited to, spine, pelvis, and limbs.

[0073] Although the present system and method for automatic control of a cranial drill has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the system and method to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages, particularly in light of the foregoing teachings. Accordingly, we intend to cover all such modifications, omission, additions and equivalents as may be included within the spirit and scope of the cmial drill system and method as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Claims

We claim:

1. An MRI-guided interventional system for guiding placement of a drill bit of a cranial drill for drilling a burr hole into a skull of a patient in vivo, the cranial drill bit placement system comprising: an MRI-compatible controller configured to send actuator commands; an MRI-compatible cranial drill system adapted to be secured to or proximate to the head of the patient, the cranial drill system including a pressure sensor, wherein the cranial drill system is adapted to receive the actuator commands and send position data and force feedback from the pressure sensor to the controller; navigation software; and a fiber optic cable connected between the controller and the navigation software; wherein the navigation software is configured for transmitting scanner control signals to the MRI scanner and receiving images generated by the MRI scanner for transmission to a display output for receiving electrical signals and for displaying corresponding images, and wherein the navigation software is adapted to receive commands based on the images.

2. The MRI-guided interventional system as recited in claim 1, further comprising a control console, wherein the fiber optic cable is connected between the controller and the control console, and wherein the controller comprises the navigation software and provides images to the display output.

3. The MRI-guided interventional system as recited in claim 1, wherein the controller comprises a robot controller and a drill controller, and further comprising a robot assistive device for receiving and sending actuator commands from and to the controller.

4. The MRI-guided interventional system as recited in claim 2, wherein the controller comprises a robot controller and a drill controller, and further comprising a robot assistive device for receiving and sending actuator commands from and to the controller.

5. The MRI-guided interventional system as recited in claim 1, wherein the fiber optic cable extends through a barrier of an MRI suite between a control room and an MRI scanner room.

6. The MRI-guided interventional system as recited in claim 2, wherein the control console is in a control room.

7. The MRI-guided interventional system as recited in claim 1, wherein the controller is in the MRI scanner room.

8. A method for MRI-guided automated placement of a cranial drill bit for drilling a burr hole in a skull of a patient in vivo, the cranial drill bit placement method comprising the steps of: providing an MRI-compatible cranial drill system including a pressure sensor; providing an MRI scanner for scanning at least a skull of the patient; providing a controller; providing a control console for communicating with the controller; and sending commands and receiving force feedback from the cranial drill system for a surgical procedure on the patient.

9. The cranial drill bit placement method as recited in claim 8, further comprising the steps of providing a robot for moving the cranial drill system; sending commands from the controller to the robot, and receiving controller feedback from the robot for moving the cranial drill bit of the cranial drill system for a performing a surgical procedure on the patient.

10. The cranial drill bit placement method as recited in claim 8, further comprising the steps of providing images from the controller, and sending emergency commands to the controller.

11. The cranial drill bit placement method as recited in claim 9, further comprising the steps of providing images from the controller, and sending emergency commands to the controller.

12. The MRI-guided interventional system as recited in claim 1, further comprising a cranial drill assembly; and a shell for housing the cranial drill assembly, the shell having an opening for passing the drill bit.

13. The MRI-guided interventional system as recited in claim 1, wherein the MRI- compatible cranial drill assembly comprisesAn axial translation subsystem movable relative to the shell for advancing and retracting the drill bit through the opening along the axis of the bit, a bit driver system, and an optical limit switch mounted on the axial translation subsystem.

14. The MRI-guided interventional system as recited in claim 13, wherein the optical limit switch comprises a sensory base, and a moving flag member.

15. The MRI-guided interventional system as recited in claim 13, wherein the axial translation subsystem comprises a rotary motor, at least one lead screw driven by the rotary motor, and a movable platform integral with the lead screw, the movable platform constrained to only linear movement such that actuation of the rotary motor drives the platform linearly in one direction or an opposite direction.

16. The MRI-guided interventional system as recited in claim 15, wherein the rotary motor is piezoelectrically actuated motor.

17. The MRI-guided interventional system as recited in claim 13, wherein the axial translation subsystem comprises a second rotary motor for driving the drill bit.

18. An MRI-guided surgical method for using a cranial drill system for automatically controlling the drill bit, the cranial drill system control method comprising the steps of: mounting a cranial drill system to or proximate to a skull of the patient; preoperatively scanning the patient with the MRI scanner for obtaining a medical image of a target area; planning a surgical process including a trajectory of the drill bit based on the images generated by the scan; verify the position of the cranial drill system and trajectory of the drill bit with a second scanning of the patient for obtaining a medical image of the patient and the cranial drill system; rotate the drill bit; provide real time scanning during the procedure with a focus on the target area for a view of the advancing drill bit; automatically advance the drill bit to a desired location along a planned trajectory based on tracking of the drill bit; provide real time force sensing of the drilling process; stop rotation of the drill bit upon significant reduction in sensed force; and retracting the drill bit leaving a burr hole in the skull of the patient.

19. The cranial drill system control method as recited in claim 18, wherein the step of mounting the cranial system comprises mounting the cranial drill system to a robot assistive device, and the step of planning a surgical process based on the images generated by the scanning comprises sending the image signals to the robot for moving the cranial drill system to the targeted region.

20. The cranial drill system control method as recited in claim 19, further comprising the steps of providing navigation software, and determining if the target area is penetrated by the drill bit.

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