US20110118597A1 - System and method for surgical instrument disablement via image-guided position feedback - Google Patents

Abstract

A system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject. In one embodiment, the system includes means for noninvasively placing a number of fiducial markers in an anatomic space of the region of interest of the living subject, means for pre-operatively measuring a location of each fiducial marker in the anatomic space, an imaging acquisition device for pre-operatively acquiring an image volume from the region of interest of the living subject, a probe for intra-operatively monitoring a location of the surgical instrument in the anatomic space, and a controller configured to perform the steps of identifying a centroid of each fiducial marker in the image volume, registering the identified centroid of each fiducial marker in the image volume to the measured location of the corresponding fiducial marker in the anatomic space to determine a registration transformation, mapping the monitored location of the surgical instrument in the anatomic space onto a corresponding location in the image volume by an inverse of the registration transformation, and generating a signal to disable the surgical instrument when the mapped location of the surgical instrument is substantially close to a boundary of the surgical site of the region of interest in the image volume.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION
• This application claims the benefit, pursuant to 35 U.S.C. §119(e), of provisional U.S. patent application Ser. No. 60/555,377, filed Mar. 22, 2004, entitled “SURGICAL INSTRUMENT DISABLEMENT VIA IMAGE-GUIDED POSITION FEEDBACK,” by Robert F. Labadie, and J. Michael Fitzpatrick, which is incorporated herein by reference in its entirety.
• Some references, which may include patents, patent applications and various publications, are cited and discussed in the description of this invention. The citation and/or discussion of such references is provided merely to clarify the description of the present invention and is not an admission that any such reference is “prior art” to the invention described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference. In terms of notation, hereinafter, “[n]” represents the nth reference cited in the reference list. For example, [7] represents the 7th reference cited in the reference list, namely, West J B, Fitzpatrick J M, Toms S, Maurer, Jr, and Maciunas R J. Fiducial point placement and the accuracy of point-based, rigid-body registration.Neurosurgery48: 810-817, 2001.
STATEMENT OF FEDERALLY-SPONSORED RESEARCH
• The present invention was made with Government support under a contract R21 EB02886-02 awarded by National Institutes of Health. The United States Government may have certain rights to this invention pursuant to these grants.
FIELD OF THE INVENTION
• The present invention generally relates to a computer-assisted surgery and in particular to the utilization of a feedback trigger during a surgery to selectively disable a surgical instrument operating in a region of interest of a living subject.
BACKGROUND OF THE INVENTION
• Radiographic imaging is often imperative for the pre-operative planning of surgical treatments for patients. Plain X-rays, computed tomography (hereinafter “CT”) images, and magnetic resonance (hereinafter “MR”) images facilitate surgical navigations. Because on their usefulness, surgeons have sought innovative ways to further incorporate radiographic imaging into the surgical suite. For years, orthopedic and vascular surgeons have relied upon intra-operative, real-time fluoroscopy, such as plain X-rays, to assess surgical treatments. More recently, real-time MR [1] and CT imaging surgical suites have been constructed where intra-operative MR or CT image is continuously updated displaying anatomic changes due to surgical treatment. These systems have found limited use due to logistic difficulties including the exorbitant cost of a dedicated CT or MR imaging system in an operative suite and the physically confined environment in which a surgeon operates.
• A more feasible option has been the use of pre-operative CT and/or MR images in an image-guided surgery (hereinafter “IGS”) where anatomic locations are continuously updated on the per-operative CT and/or MR images as specified by a surgical probe. The concept of the image-guided surgery dated back to the 1940's [3]. However, widespread acceptance of the concept did not occur until radiographic advances in the 1970's that made CT and MR images routinely available. Image-guided surgical systems, which are analogous to global-positioning systems (hereinafter “GPS”), have since found widespread use in neurosurgery [4] and sinus surgery [5]. In general, An IGS system includes a pre-operative radiographic image (CT or MR image) that is acquired from a patient and digitized and stored on a computer. Within the operating room (hereinafter “OR”), the pre-operative radiographic image are registered to the anesthetized patient by correlating landmarks found on the pre-operative radiographic image with the landmarks on the anesthetized patient. Typical landmarks used for registration are anatomic points and/or fiducial markers attached to the skin or implanted in bone of a patient. Registration creates a transformation matrix that allows a direct mapping of the patient's current anatomy to the corresponding pre-operative radiographic image. Once registration has taken place, for example, using an electronically visible probe, such as infrared optical system and/or electromagnetic system, to detect a location of each fiducial marker in the patient, i.e., the physical space, that is registered to in a radiographic image space. The probe can be used as a pointer to identify surgical anatomy on CT or MR images.
• Crucial to limiting error in IGS systems is registration of the pre-operative radiographic image to the surgical field of interest in the anesthetized patient.
• Registration landmarks, for example, anatomic landmarks and/or fiducial markers, need to be immobile relative to the anatomy and arranged such that they surround the surgical field of interest. While multiple anatomic landmarks would initially appear useful, soft tissue, for instance, skin and muscle, relaxes and distorts under general anesthesia making boney landmarks necessary for accurate registration. A solution has been to implant markers into bone of a patient. This is routinely used in neurosurgery where screws are placed into the cranium prior to pre-operative radiographic imaging and these screws serve as landmarks for registration. While accuracy with such systems is impressive [6, 7], it does involve the invasive placement of bone screws with small, yet real, risk of infection and cosmetic deformity. Another solution is to use skin markers or skin contours. Such systems have shown decreased accuracy that is unacceptable in otologic applications [8].
• The most common ear disorders of human being that require surgical treatments are chronic serous otitis media (hereinafter “CSOM”) and cholesteatoma. The CSOM is characterized by inflammation of the mucous membrane lining the middle ear that does not respond to medical therapy. The cholesteatoma contains keratinizing squamous epithelium (skin) trapped within the middle ear cavity and leads to chronic infection, hearing loss, facial nerve paralysis, and vertigo. Both the CSOM and cholesteatoma are usually treated by an otologic surgery, for example, through a mastoidectomy, to remove diseased tissues from the temporal bone encasing the ear using a surgical drill and/or knife. As a result, adjacent structures surrounding the surgical site of the temporal bone, such as the facial nerve, the inner ear, the floor of the cranial vault, the internal jugular vein and the carotid artery, are at great risk during the surgical treatment.
• It has been shown that IGS systems can improve overall standards of surgical treatments in both neurosurgery and sinus surgery. Specifically, IGS systems have improved surgical accuracy and reduce the risk of major complications in sinus surgery [9], and decreased operative time for neurosurgical procedures thus cutting costs [10]. In addition, patients treated with an IGS have more complete resection of diseased tissues with less collateral damage to healthy tissues [11] than that treated with a traditional surgery. It is anticipated that such advantages of the IGS systems would be also applicable to an otologic surgery. Epidemiologic and economic data supports the usefulness of an IGS in otologic procedures. However, applications have been limited by the need for millimeter and sub-millimeter accuracies to prevent injury to adjacent structures, such as the facial nerve and the inner ear. Therefore, a heretofore unaddressed need still exists in the art to address the aforementioned deficiencies and inadequacies.
SUMMARY OF THE INVENTION
• The present invention, in one aspect, relates to a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion. The present invention can be practiced with respect to several surgical instruments and any combinations of them. As non-limiting examples, the surgical instrument can be a drill, and the distal end portion of the surgical instrument is the tip of the drill. The surgical instrument can be a surgical scalpel, and the distal end portion of the surgical instrument is the cutting portion of the surgical scalpel. The surgical instrument can also be a suction device, and the distal end portion of the surgical instrument is the sucking portion of the suction device. The region of interest of the living subject may correspond to an ear portion, a mouth portion, a head portion, or other body portions of the living subject.
• In one embodiment, the system includes means for noninvasively placing a number, M, of fiducial markers in an anatomic space of the region of interest of the living subject. The placing means has a locking dental acrylic resin splint (hereinafter “LADS”) mountable to a maxilla of the living subject, where the LADS includes a central portion with an extension at a predetermined position, and two lateral portions attached to the central portion. The placing means further has a fiducial frame attachable to the LADS by the extension for receiving the number M of fiducial markers. The fiducial frame comprises a frame structure, a first panel and an opposite, second panel extending upwardly from the frame structure, each of the first panel and the second panel defining a number of holes for receiving a corresponding number of fiducial markers. The fiducial frame is configured such that when the number M of fiducial markers are received therein, the centroid of each fiducial marker approximates the surgical site of the ear portion of the living subject and distance between at least one pair of two corresponding fiducial markers is maximized so as to minimize a target registration error.
• The system further includes means for pre-operatively measuring a location of each fiducial marker in the anatomic space of the region of interest of the living subject, an imaging acquisition device for pre-operatively acquiring an image volume from the region of interest of the living subject, where the pre-operatively acquired image volume includes the image of at least two of M fiducial markers, and a probe operatively coupled with the surgical instrument for intra-operatively monitoring a location of the distal end portion of the surgical instrument in the anatomic space of the region of interest of the living subject. Moreover, the system includes a controller operatively coupled with the measuring means, the imaging acquisition device, the probe, and the surgical instrument, respectively. The controller is configured to perform the steps of identifying a centroid of each fiducial marker in the pre-operatively acquired image volume, registering the identified centroid of each fiducial marker in the pre-operatively acquired image volume to the pre-operatively measured location of the corresponding fiducial marker in the anatomic space so as to determine a registration transformation, mapping the intra-operatively monitored location of the distal end portion of the surgical instrument in the anatomic space onto a corresponding location in the pre-operatively acquired image volume by an inverse of the registration transformation, and generating a signal to disable the surgical instrument when the mapped location of the distal end portion of the surgical instrument is substantially close to a boundary of the surgical site of the region of interest in the pre-operatively acquired image volume. Furthermore, the system includes a number, N, of surgical markers, each placed in a surgically significant anatomic location serving as a registration target.
• Moreover, the system has an alarm device communicating with the controller for generating an alarm when the mapped location of the distal end portion of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the region of interest in the pre-operatively acquired image volume. Additionally, the system includes an interlock device operatively associated with the surgical instrument and communicating with the controller, where the interlock device disables the surgical instrument when the mapped location of the distal end portion of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the region of interest in the pre-operatively acquired image volume.
• In another aspect, the present invention relates to a method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion, the region of interest of the living subject is surrounded with a plurality of markers. The plurality of markers includes a number, M, of fiducial markers determining an image registration and a number, N, of surgical markers with each surgical marker placed in a surgically significant anatomic location serving as a registration target. The region of interest of the living subject corresponds to an ear portion of the living subject.
• In one embodiment, the method includes the step of pre-operatively acquiring an image volume from the region of interest of the living subject, where the pre-operatively acquired image volume contains the image of at least two of M fiducial markers. Furthermore, the method has the steps of identifying a centroid of each fiducial marker from the pre-operatively acquired image volume, pre-operatively measuring a location of each fiducial marker in an anatomic space of the region of interest of the living subject, registering the identified centroid of each fiducial marker in the pre-operatively acquired image volume to the pre-operatively measured location of the corresponding fiducial marker in the anatomic space so as to determine a registration transformation, intra-operatively monitoring a location of the distal end portion of the surgical instrument in the anatomic space of the region of interest of the living subject, and mapping the intra-operatively monitored location of the distal end portion of the surgical instrument in the anatomic space onto a corresponding location in the pre-operatively acquired image volume by an inverse of the registration transformation. Moreover, the method includes the step of generating a signal to disable the surgical instrument when the mapped location of the distal end portion of the surgical instrument is substantially close to a boundary of the surgical site of the region of interest of the living subject in the pre-operatively acquired image volume.
• In one embodiment, the method further has the step of mounting an LADS with an attached fiducial frame onto a maxilla of the living subject, where the fiducial frame is configured such that when the number M of fiducial markers are received therein, the centroid of each fiducial marker approximates the surgical site of the ear portion of the living subject and distance between at least one pair of two corresponding fiducial markers is maximized so as to minimize a target registration error. Additionally, the method has the step of generating an alarm when the mapped location of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the pre-operatively acquired image volume.
• In yet another aspect, the present invention relates to a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion and is operable by a surgeon during a surgery. In one embodiment, the system has an eye-tracking device operatively coupled with the surgical instrument for intra-operatively tracking the visual line of sight of the surgeon and a location of the distal end portion of the surgical instrument in the region of interest of the living subject, respectively, and a controller operatively coupled with the surgical instrument and the eye-tracking device, respectively. The controller is configured to perform during the surgery the steps of determining an angle between a visual path connecting a predetermined point of the eye-tracking device and the distal end portion of the surgical instrument in the region of interest of the living subject and the line of sight of the surgeon, and generating a signal to disable the surgical instrument when the angle is larger than a predetermined angle. In one embodiment, the eye-tracking device includes a head-hold device and has a sensor.
• The system, in one embodiment, has a display communicating with the controller and the eye-tracking device for displaying the tracked line of sight of the surgeon and the tracked location of the distal end portion of the surgical instrument in the region of interest of the living subject, respectively.
• In a further aspect, the present invention relates to a method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion and is operable by a surgeon during a surgery. In one embodiment, the method includes the steps of intra-operatively tracking the visual line of sight of the surgeon and a location of the distal end portion of the surgical instrument in the region of interest of the living subject, respectively, determining an angle between a visual path connecting a predetermined point of the eye-tracking device and the distal end portion of the surgical instrument in the region of interest of the living subject and the line of sight of the surgeon, and generating a signal to disable the surgical instrument when the angle is larger than a predetermined angle.
• In yet a further aspect, the present invention relates to a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion and is operable by a surgeon during a surgery. In one embodiment, the system has a probe for intra-operatively monitoring an electrophysiological condition of the living subject in the region of interest, and a controller operatively coupled with the surgical instrument and the probe, respectively. The controller is configured to perform during the surgery the steps of determining a variation of the electrophysiological condition of the living subject from an initial state of the living subject in the region of interest, and generating a signal to disable the surgical instrument when the variation of the electrophysiological condition is greater then a predetermined value.
• The system further has at least one of a display and an audio device for visually and/or audibly displaying the intra-operatively monitored electrophysiological condition of the living subject in the region of interest, respectively.
• In one embodiment, the probe comprises at least one needle electrode placed in the region of interest of the living subject, and the electrophysiological condition comprises an electromyogram of electrical activities of muscles of the region of interest of the living subject. In another embodiment, the probe comprises a Doppler vascular probe, and the electrophysiological condition includes a flow rate of blood vessels of the region of interest of the living subject. In an alternative embodiment, the probe has a temperature-sensing device, and the electrophysiological condition includes a temperature of tissues of the region of interest of the living subject. In one embodiment, the probe has an oxygenation detector, and the electrophysiological condition comprises a venous oxygenation saturation and an arterial oxygenation saturation of the region of interest of the living subject. In another embodiment, the probe includes a tissue boundary detector, where the tissue boundary detector comprises at least one of an ultrasound sensing device, an infrared radiation sensing device, an ultraviolet radiation sensing device, a fluorescent radiation sensing device, and a video frame device. The electrophysiological condition includes a tissue type identification of tissues at the distal end portion of the surgical instrument in the region of interest of the living subject. The electrophysiological condition may also relate to a volume of suction from the region of interest of the living subject.
• In one aspect, the present invention relates to a method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, where the surgical instrument has a distal end portion and is operable by a surgeon during a surgery. In one embodiment, the method includes the steps of intra-operatively monitoring the electrophysiological condition of the living subject in the region of interest, determining a variation of the electrophysiological condition of the living subject from an initial state of the living subject in the region of interest, and generating a signal to disable the surgical instrument when the variation of the electrophysiological condition is greater than a predetermined value.
• These and other aspects of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 shows a perspective view of a LADS according to one embodiment of the present invention: (A) the LADS dismissed, and (B) the LADS mounted to a maxilla of a human anatomy.
• FIG. 2 shows a perspective view of a fiducial frame: (A) the fiducial frame according to one embodiment of the present invention, (B) the fiducial frame according to another embodiment, and (C) the fiducial frame according to an alternative embodiment.
• FIG. 3 shows a perspective view of placing means including a LADS and a fiducial frame mounted to a skull of a human anatomy according to one embodiment of the present invention: (A) a side perspective view, and (B) a front perspective view.
• FIG. 4 shows a flowchart for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject according to one embodiment of the present invention.
• FIG. 5 shows schematically a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject according to one embodiment of the present invention.
• FIG. 6 shows schematically a block diagram for a system for selectively disabling a surgical instrument operating in a surgical target of a living subject according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• The present invention is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Various embodiments of the invention are now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
• The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings1-6. In accordance with the purposes of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject. The living subject can be a human patient or an animal. In one embodiment, a human patient is employed to practice the current invention, a region of interest of the patient corresponds to an ear portion of the patient, and the surgical instrument having a distal end portion and is operable by a surgeon during a surgery.
• Referring first toFIG. 6, a block diagram for asystem600 is schematically shown. In general, thesystem600 can be utilized by at least one surgical professional610 for operating a surgery on a surgical target, which may includes pre-operatively surgery planning, intra-operatively surgery operation and post-operatively surgery evaluation. Thesystem600 includes asurgical instrument620 operable by the at least one surgical professional610 for operating the surgery with respect to thesurgical target630. Thesystem600 further has adetector640 communicatable with the at least one surgical professional610, thesurgical instrument620 and thesurgical target630, for intra-operatively detecting a visual condition of the surgical professional610, a location of thesurgical instrument620, and an electrophysiological condition of thesurgical target630, respectively. Moreover, thesystem600 has acontroller650 communicating with thedetector640, and thesurgical instrument620, respectively, for receiving data from thedetector640, processing them therein and generating a signal to disable thesurgical instrument620 when a predetermined condition in the processed data is identified, as further described below. Thecontroller650 is programmable by the surgical professional610 or other authorized users such as surgical assistants. Furthermore, thesystem600 includes adisplay660 communicatable with thecontroller650 for intra-operatively displaying the detected visual condition of sight of the at least one surgical professional610, the location of thesurgical instrument620, and the electrophysiological condition of the living subject in thesurgical target630, respectively. The information on thedisplay660 is available to the at least one surgical professional610 or surgical assistants.
• Specifically, the system, in one embodiment, includes means for noninvasively placing a number, M, of fiducial markers in an anatomic space of the ear portion of a patient. Referring in general toFIGS. 1-3, and in particular toFIG. 1, the placing means includes a LADS100 (Peterman Dental Lab, Nashville, Tenn.) that is mounted onto amaxilla180 of the patient. TheLADS100 is in the form of a dental bite-block that may be customizedly molded for individual maxillary dental patterns. TheLADS100 has acentral portion110 that imprints the lingual and occlusal surfaces of the maxillary teeth with anextension120 at apredetermined position130 and twolateral portions140aand140bthat imprint the buccal surfaces and are attached to thecentral portion110, respectively. Theextension120 has mounting means125, which in this embodiment has one or more mounting holes formed on theextension120. Thecentral portion110 andlateral portions140aand140bare secured onto themaxilla180 using one ormore screws150 that hold thelateral portions140aand140bsecurely with thecentral portion110 in cooperation with corresponding mounting holes125. The geometry of the teeth, being narrower at the insertion into the gums, ensures a tight, reliable fit.
• The placing means further includes a fiducial frame that is attached to the LADS by the extension for receiving the number M of fiducial markers. Referring now toFIG. 2A, in one embodiment, afiducial frame200aincludes aU-shaped frame structure210 having afirst end portion216aand asecond end portion216b,afirst panel220aextending upwardly from thefirst end portion216aof theframe structure210, and an opposite,second panel220bextending upwardly from thesecond end portion216bof theframe structure210. Each of thefirst panel220aand thesecond panel220bhas one or more holes formed therein for receiving corresponding marker(s)225. In one embodiment, commercially available markers225 (Acustar®, Z-Kat, Inc., Hollywood, Fla.) are received into the holes and mounted on thefirst panel220aand thesecond panel220bof thefiducial frame200a,respectively. Thefiducial frame200afurther has anengagement projection215 located at a predetermined position in theframe structure210 for engaging thefiducial frame200ato theLADS100 through corresponding mounting means125.
• Referring toFIG. 2B, afiducial frame200bis shown according to another embodiment of the present invention. Thefiducial frame200bhas aframe structure240. Theframe structure240 includes afirst arm244a,asecond arm244b,ashoulder242 connecting thefirst arm244aand thesecond arm244b,a first adjusting means243alocated in the junction of theshoulder242 and thefirst arm244a,and a second adjusting means243blocated in the junction of theshoulder242 and thesecond arm243b.Thefirst arm244ahas anend portion246a,and thesecond arm244bhas anend portion246b.Thefiducial frame200bfurther has afirst panel250aand an opposite,second panels250brespectively extending upwardly from theend portions246aand246bof thefirst arm244aand thesecond arm244bof theframe structure240. Each of thefirst panel250aand thesecond panel250bis structured to receive several correspondingfiducial markers255. Thefiducial frame200bfurther has anengagement projection245 located at a predetermined position in theshoulder242 of theframe structure210 for engaging thefiducial frame200bto theLADS100 through corresponding mounting means125. In this embodiment, the size of thefiducial frame200bcan be adjusted by the adjusting means243aand243bto accommodate skulls of varying dimensions of a living subject.
• FIG. 2C shows afiducial frame200caccording to an alternative embodiment of the present invention. Thefiducial frame200cincludes aframe structure270 that has ashoulder272, afirst arm274aand asecond arm274bextending from theshoulder272, respectively. Thefirst arm274ahas anend portion276a,and thesecond arm274bhas anend portion276b.Thefiducial frame200cfurther has afirst panel280aand an opposite,second panels280brespectively extending upwardly from theend portions276aand276bof thefirst arm274aand thesecond arm274bof theframe structure270. Each of thefirst panel280aand thesecond panel280bis structured to receive several correspondingfiducial markers285. Thefiducial frame200cfurther has anengagement projection275 located at a predetermined position in theshoulder272 of theframe structure270 for engaging thefiducial frame200cto theLADS100 through corresponding mounting means125. Thefiducial frame200cis featured at minimizing weight and optimizing the number of fiducial markers necessary to achieve sub-millimeter accuracy.
• A fiducial frame is made of materials such that the fiducial frame is considered as a rigid-body, i.e., no appreciable deformity under normal use, and has a weight minimized so as to prevent excess torques that may injure dentition. In one embodiment, spun carbon fibers are used to construct the fiducial frame, which minimize weight while maximizing rigidity of the fiducial frame.
• Referring toFIGS. 3A and 3B, a placing means300 is secured to askull390 of a human by mounting aLADS350 onto the maxilla. In this embodiment, afiducial frame310 shown inFIG. 2C is attached to theLADS350 by mountingmeans355.
• Thefiducial frame310 is configured such that when a number offiducial markers325 are received in thefirst panel320aand thesecond panel320b,respectively, the centroid of eachfiducial marker325 approximates a predeterminedsurgical site380 in theear portion370 of the human and the distance between the correspondingfiducial markers325 positioned in each of thefirst panel320aand thesecond panel320bis maximized so as to minimize a TRE. Rigid fixation of fiducial markers to thefirst panel320aand thesecond panel320bis advantageous because it avoids drilling into the skull. In one embodiment, nine fiducial markers, such as Acustar® of Z-Kat, Inc., are received in each of thefirst panel320aand thesecond panel320bof thefiducial frame310. The eighteen markers are served as fiducial markers for registration.
• Furthermore, the system includes an image acquisition device (not shown), such as a CT imaging scanner or a MR imaging scanner, for pre-operatively acquiring an image volume, i.e., a three-dimensional (hereinafter “3D”) radiographic image, which contains the eighteen fiducial markers from the ear portion of the patient. In one embodiment, the image volume, such a CT image, is acquired using clinically applicable, temporal-bone algorithms with scan thickness of about 0.5 mm. Moreover, the system includes means for pre-operatively measuring a location of each fiducial marker in the anatomic space of the ear potion of the patient. In one embodiment, a commercially available infrared optical tracking system (Polaris®, Northern Digital Corp., Waterloo, Canada) is employed to measure the location of each fiducial marker in the anatomic space of the ear potion of the patient. Other tracking systems can also be used to practice the current invention. The system further includes a surgical probe operatively coupled with the surgical instrument to detect a location of the distal end portion of the surgical instrument in anatomic space of the ear portion of the patient during the surgical treatment. In one embodiment, the surgical probe comprises an infrared optical tracking system, and the surgical instrument includes a high-speed surgical drill fitted with infrared emitters that is visible to the infrared optical tracking system.
• Additionally, the system includes a controller operatively coupled with the image acquisition device, the measuring means and the surgical probe, respectively.
• The controller in one embodiment includes a computer and is configured to (i) identify a centroid of each fiducial marker in the pre-operatively acquired 3D radiographic image, for example, a CT image volume, (ii) register the identified centroid of each fiducial marker in the pre-operatively acquired 3D radiographic image to the pre-operatively measured location of the corresponding fiducial marker in the anatomic space so as to determine a registration transformation, (iii) map the intra-operatively monitored location of the distal end portion of the surgical instrument in the anatomic space onto a corresponding location in the pre-operatively acquired 3D radiographic image by an inverse of the registration transformation, and (iv) generate a signal to disable the surgical instrument when the mapped location of the distal end portion of the surgical instrument is substantially close to a boundary of the surgical site of the region of interest in the pre-operatively acquired 3D radiographic image.
• In one embodiment, the system also includes an interlock device operatively associated with the surgical instrument and communicating with the controller. The interlock device in one embodiment includes an articulated/robotic arm that is programmed to control the surgical instrument to perform mastoidectomies based on pre-operative CT scans which have contoured to indicate desired surgical excavation, and disable the surgical instrument when the mapped location of the distal end portion of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the region of interest in the pre-operatively acquired image volume. In one embodiment, the predetermined distance to the boundary of the surgical site is about 0.5 mm.
• The system further includes an audio alarm coupled with the controller for generating an alarm when the mapped location of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the acquired 3D radiographic image and a video frame coupled with the controller for displaying the precise anatomic location of the transgression as feedback to the operator.
• Additionally, the system in one embodiment has two markers placed at surgically significant anatomic locations: the internal auditory canal and stylomastoid foramen of the ear portion of the patient, respectively. These two markers served as surgical targets for the purpose of estimating target registration error. Other anatomic landmarks which are stable and repeatably identifiable both on CT imaging scans and within the OR can also serve as surgical targets. They are any and/or all of the following: (i) the spine of Henle—a small outcrop of bone in the lateral external auditory canal, (ii) the lambda suture—a junction of three boney plates visible on the surface on the skull behind the ear, (iii) the capitulum of the stapes—the top portion of the third ear bone, (iv) the cochleaform process—a small outcropping of bone into which a tendon, the tensor tympani, attaches, (v) the pyramidal process—another small outcropping of bone into which a tendon, the stapedial, tendon attaches, (vi) the midpoint of the subiculum—a boney ridge which separates the oval window and the round window, and (vii) the neck of the malleus, a relatively constant position of the first ear bone.
• The registration between the anatomic space and the CT image space is performed using various subsets of the fiducial markers. Each resulting transformation is applied to each surgical target marker in the anatomic space. The disparity between the transformed position and the measured position in the CT image space serves as a measure of registration error. Geometric arrangement of fiducial markers and their relation to target position affects error as expected from previous theoretical predictions [12]. Specifically, target registration errors are minimized with arrangement of the fiducial markers surrounding the surgical site of interest such that the centroid of the fiducial markers approximates the surgical site of interest. Also, registration accuracy is improved with the number of fiducial markers but with diminishing returns over a critical number. This becomes important in high-resolution CT scanning with the scannable volume is finite thus limiting the feasible number of markers. In one embodiment, with all 18 fiducial markers used for registration, that is each side of the ear portion of the patent has 9 fiducial markers, which are received in a first panel and a second panel of a fiducial frame, respectively, TRE for the surgically significant anatomic locations including an internal auditory canal and a stylomastoid foramen are TRE1=0.41 mm and TRE2=0.90 mm, respectively. In another embodiment, surrounding the side of interest, where a surgical site is located, of the ear portion of the patent with 9 markers and balancing this with a single, centrally placed marker on the contralateral side of the ear portion of the patient produces similar results with TRE1=0.52 mm and TRE2=0.90 mm. However, for an inverse situation, that is, surrounding the contralateral side of the surgical site of the ear portion of the patient with 9 fiducial markers and balancing the side of the surgical site of the ear portion of the patient with a single marker, it produces worse results with TRE1=1.26 mm and TRE2=1.80 mm for the internal auditory canal and stylomastoid foramen targets, respectively. These are the largest registration target errors occurred among 17 different configurations of 18 fiducial markers. TREs with a sub-millimeter accuracy (<1 mm) are reproducibly achievable using 5 fiducial markers surrounding the side of the surgical site of the ear portion of the patient and a single, centrally located fiducial marker balancing on the contralateral side of the ear potion of the patient for a critical number of6 total fiducial markers. This makes image guided otologic surgery with submillimeter accuracy achievable with a minimally invasive fiducial frame.
• The present invention, in another aspect, relates to a method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a patient thereof responsive to a position feedback of the surgical instrument that has a distal end portion. For example, the surgical instrument can be a surgical drill, a surgical scalpel and/or a suction device operable by a surgeon during surgery such as an otologic surgery to a human patient, and the region of interest of the patient corresponds to an ear portion of the patient. Prior to the otologic surgery, an Institutional Review Board (Vanderbilt University, Nashville, Tenn.) approval for surgical procedures of the otologic surgery for human patients is obtained and patient consent for the otologic surgery is acquired. A patient-specified LADS is constructed in a dental lab, for example, Peterman Dental Lab, after maxillary impressions are taken from the patient. The patient-specified LADS is then attached to a fiducial frame and mounted onto the maxilla of the patient, where the fiducial frame is configured such that when the number M of fiducial markers are received therein, the centroid of each fiducial marker approximates the surgical site of the ear portion of the patient and distance between two corresponding fiducial markers is maximized so as to minimize a target registration error. In one embodiment, each side of the ear portion of the patient is surrounded with nine fiducial markers. In addition, two surgical markers are placed in close proximity to 2 anatomically important structures, such as an internal auditory canal and a stylomastoid foramen of the ear portion of the patient.
• In one embodiment, the method, as shown inFIG. 4, includes the following steps: atstep410, an image volume is acquired pre-operatively from the ear portion of the patient, where the pre-operatively acquired image volume contains the image of at least two of M fiducial markers. In one embodiment, three sequential CT imaging scans from the ear portion of the patient wearing the LADS and fiducial frame are taken. Other numbers of sequential CT imaging scans can also be taken. The fiducial frame is removed from and reattached to the LADS between two CT imaging scans. Multiple CT imaging scans are necessary in determining fiducial registration error (hereinafter “FRE”) of the image space, which is employed to determine TRE. These FREs are averaged using sum of squares to determine an average FRE. Atstep420, a centroid of each fiducial marker is identified from the pre-operatively acquired image volume. In one embodiment, the image volumes (3D CT images) are reconstructed from the CT imaging scans by utilizing a high-performance computer. On these reconstructed image volumes, voxels (i.e., a surgical site) that lie within the ear portion of the patient are selected by the surgeon. In other words, a surgical excavation, i.e., a mastoidectomy, is pre-operatively planned based on the radiographic images.
• After pre-operatively acquiring image volumes of the patient, the LADS and the fiducial frame are removed and saved for the patient. In the OR, after performing a general anesthesia, the patient is re-fitted with his/her customized LADS and the fiducial frame. A location of each fiducial marker in an anatomic space of the ear portion of the patient is measured using an infrared optical tracking system, such as Polaris®, atstep430. The identified centroid of each fiducial marker in the pre-operatively acquired image volume is registered to the pre-operatively measured location of the corresponding fiducial marker in the anatomic space atstep440. The image registration determines a registration transformation and is performed by a computer in conjunction with the infrared optical tracking system and customized software. The registration transformation, in one embodiment, includes a rigid-body transformation. During the surgery, a location of the distal end portion of the surgical instrument in the anatomic space of the ear portion of the patient is monitored atstep450. In one embodiment, a high-speed surgical drill fitted with IR emitters is employed for the otologic surgery, and its tip location of the surgical drill is monitored by the infrared optical tracking system. Atstep460, the intra-operatively monitored location of the distal end portion of the surgical instrument in the anatomic space is mapped onto a corresponding location in the pre-operatively acquired image volume by an inverse of the registration transformation. The mapping step in one embodiment is performed with the computer. When the mapped location of the surgical instrument is within a predetermined distance to the boundary of the surgical site in the pre-operatively acquired image volume, a controller, such as a computer coupled with the surgical instrument, generates a signal to disable the surgical instrument atstep470. In one embodiment, the predetermined distance is about 0.5 mm. Software codes and electric circuits for controlling the surgical instrument in the present invention are custom-designed. In the present invention, among other things, unique to the otologic surgery is that the surgical instrument, a high-speed surgical drill, can be quickly disabled to prevent collateral damage to healthy tissues. The disablement includes simply turning off the rotation of the bit using active braking when the surgical instrument leaves the surgeon-identified surgical site.
• According to one embodiment of the current invention, anatomically significant landmarks, as described above, are intra-operatively and post-operatively acquired, respectively, in a blinded fashion, i.e., the surgeon points to a structure and an assistant acquires its position and label it. These data points are used to analyze the TRE of these anatomically significant points.
• In addition, three endpoints of the surgery including (i) number of surgical transgressions beyond the safe surgical field, (ii) volume of tissues removed, and (iii) time of the surgery, are measured. Endpoint (i) is corresponding to an index of safety of the surgery and measured during the otologic surgery. Endpoint (ii) is assessed by obtaining post-surgical CT imaging scans to determine what percentage of the original planned excavation occurred. And endpoint (iii) corresponds to the operating time of the surgery from the start to the end of the surgery. Endpoints (i) and (iii) are corresponding to indices of efficiency of the surgery. Statistically appropriate comparisons are made after determining the distribution of the indices of efficiency of the surgery. Analysis of the endpoint data is performed with SigmaStat® Statistical Software (SPSS Science, Inc., Chicago, Ill.).
• Referring now toFIG. 5, asystem500 has asurgical instrument520 operating in asurgical site530 of a region of interest of a patient. Thesurgical instrument520 has adistal end portion522 and is operable by asurgeon510 during a surgery. Thesurgical instrument520 may be a commercially available surgical drill, a surgical scalpel, a suction device such as a surgical pump or tube, or other surgical instruments and any combination of them. Thesystem500 further has an eye-trackingdevice540 for intra-operatively tracking the visual line ofsight570 of thesurgeon510 and a location of thedistal end portion522 of thesurgical instrument520 in the region of interest of the patient, respectively. In one embodiment, the eye-trackingdevice540 includes a head-hold device, such as EyeLink® II, (SR Research, Ltd., Osgoode, Canada). Other eye-tracking devices can also be employed to practice the current invention. Thesystem500 also includes acontroller550 that is operatively coupled with thesurgical instrument520 and the eye-trackingdevice540, respectively. Thecontroller550, such as a computer, is configured to perform during the surgery the step of processing the intra-operatively tracked visual line ofsight570 of thesurgeon510 and the location of thedistal end portion522 of thesurgical instrument520 in the region of interest of the patient to determine an angle, α, between avisual path580 connecting apredetermined point542 of the eye-trackingdevice540 and thedistal end portion522 of thesurgical instrument520 in the region of interest of the patient and the line ofsight570 of thesurgeon510. Thecontroller550 is further configured to perform the step of generating a signal to disable thesurgical instrument520 when the angle a is larger than a predetermined angle as a threshold. In one embodiment, thecontroller550 is associated with a computer.
• In one embodiment, thesystem500 has adisplay560 communicatable with thecontroller550 and the eye-trackingdevice540 for displaying the tracked line ofsight570 of thesurgeon510 and the tracked location of thedistal end portion522 of thesurgical instrument520 in the region of interest of the patient, respectively.
• The present invention, in one aspect, relates to a system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a patient, where the surgical instrument has a distal end portion and is operable by a surgeon during a surgery. In one embodiment, the system has a probe adapted for intra-operatively monitoring an electrophysiological condition of the patient in the region of interest, and a controller that is operatively coupled with the surgical instrument and the probe, respectively. The controller is further configured to perform during the surgery the steps of processing the intra-operatively monitored electrophysiological condition of the patient in the region of interest to identify a variation of the electrophysiological condition from an initial state of the patient in the region of interest, and generating a signal to disable the surgical instrument when the variation of the electrophysiological condition of the patient in the region of interest is greater than a predetermined value. The controller is associated with a computer.
• In one embodiment, the probe has at least one needle electrode placed in the region of interest of the patent adapted for intra-operatively recording an electromyogram of electrical activities of muscles of the region of interest of the patient. When a myogenic potential is recorded by the at least one needle electrode, the controller will generate a signal to disable the surgical instrument.
• The probe in another embodiment has a Doppler vascular probe adapted for intra-operatively monitoring a flow rate of blood vessels of the region of interest of the patient. When a variation of the flow rate of blood vessels of the region of interest of the patient is greater than a predetermined value, the controller will generate a signal to disable the surgical instrument.
• In yet another embodiment, the probe has a temperature-sensing device adapted for intra-operatively measuring a temperature of tissues of the region of interest of the patient. When a variation of the tissue temperature of the region of interest of the patient is greater than a predetermined value, the controller will generate a signal to disable the surgical instrument.
• In an alternative embodiment, the probe has an oxygenation detector adapted for intra-operatively detecting a venous oxygenation saturation and an arterial oxygenation saturation of the region of interest of the patient intra-operatively monitored by the oxygenation detector. When an alteration of the venous oxygenation saturation versus the arterial oxygenation saturation of the region of interest of the patient is identified, the controller will generate a signal to disable the surgical instrument.
• The probe, in one embodiment, has a tissue boundary detector, where the tissue boundary detector includes at least one of an ultrasound sensing device, an infrared radiation sensing device, an ultraviolet radiation sensing device, a fluorescent radiation sensing device, and a video frame device. The tissue boundary detector is adapted for intra-operatively identifying a tissue type of tissues at the distal end portion of the surgical instrument in the region of interest of the patient. When the tissue type of tissues at the distal end portion of the surgical instrument is changed, the controller will generate a signal to disable the surgical instrument.
• The present invention, among other things, discloses a system and method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, in response to a position feedback of the surgical instrument, an electrophysiological condition of the living subject in a region of interest, and a visual condition of sight of a surgeon who operates a surgery, respectively.
• The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.
• The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.
REFERENCE LIST
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• [2]. Lunsford L D, Kondziolka D, Bissonette D J, Intra-operative imaging of the brain,Stereotact Funct Neurosurg66(1-3):58-64, 1996.
• [3]. Spiegel E A, Wycis H T, and Marks M, Lee A. Stereotactic apparatus for operations on the human brain,Science106:349-50, 1947.
• [4]. Galloway R L, Maciunas R J and Edwards C A. Interactive, Image-Guided Neurosurgery,IEEE Transactions on BME39(12):1126-1231, 1992.
• [5]. Fried M P, Kleefield J, Gopal H, Reardon E, Ho B T, and Kuhn F A. Image-guided endoscopic surgery: results of accuracy and performance in a multi-center clinical study using an electromagnetic tracking system.Laryngoscope107:594-601, 1997.
• [6]. Maurer C R Jr, Fitzpatrick J M, Wang M Y, Galloway R L Jr, Maciunas R J and Allen, G S, Registration of head volume images using implantable fiducial markers,IEEE Trans Med Imaging16(4):447-62, 1997.
• [7]. West J B, Fitzpatrick J M, Toms S, Maurer, Jr, and Maciunas R J. Fiducial point placement and the accuracy of point-based, rigid-body registration.Neurosurgery48:810-817, 2001.
• [8]. West J, Fitzpatrick T M, Wang M Y, Dawant B M, Maurer C R Jr, Kessler R M, Maciunas R J, Barillot C, Lemoine D, Collignon A, Maes F, Suetens P, Vandermeulen D, van den Elsen P A, Napel S, Sumanaweera T S, Harkness B, Hemler P F, Hill D L, Hawkes D J, Studholme C, Maintz T B, Viergever M A, Malandain G, Woods R P, et al. Comparison and evaluation of retrospective intermodality brain image registration techniques.J of Computer Assisted Tomography21(4):554-66, 1997.
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Claims (17)

1-19. (canceled)

20. A system for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, wherein the surgical instrument has a distal end portion and is operable by a surgeon during a surgery, comprising:

(a) a probe for intra-operatively monitoring a physiological condition of the living subject in the region of interest during the surgery; and

(b) a controller operatively coupled with the surgical instrument and the probe, respectively, and configured to perform during the surgery the steps of:

(i) determining a variation of the physiological condition of the living subject from an initial state of the living subject in the region of interest; and

(ii) generating a signal to disable the surgical instrument when the variation of the physiological condition is greater then a predetermined value, wherein the probe comprises at least one of a needle electrode placed in the region of interest of the living subject, a Doppler vascular probe, a temperature sensing device, an oxygenation detector, and a tissue boundary detector.

21. The system ofclaim 20, further comprising at least one of a display and an audio device for visually and/or audibly displaying the intra-operatively monitored physiological condition of the living subject in the region of interest, respectively.

22. (canceled)

23. The system ofclaim 20, wherein the physiological condition comprises an electromyogram of electrical activities of muscles of the region of interest of the living subject.

24. (canceled)

25. The system ofclaim 20, wherein the physiological condition comprises a flow rate of blood vessels of the region of interest of the living subject.

26. (canceled)

27. The system ofclaim 20, wherein the physiological condition comprises a temperature of tissues of the region of interest of the living subject.

28. (canceled)

29. The system ofclaim 20, wherein the physiological condition comprises a venous oxygenation saturation and an arterial oxygenation saturation of the region of interest of the living subject.

30. (canceled)

31. The system ofclaim 20, wherein the tissue boundary detector comprises at least one of an ultrasound sensing device, an infrared radiation sensing device, an ultraviolet radiation sensing device, a fluorescent radiation sensing device, and a video frame device.

32. The system ofclaim 31, wherein the physiological condition comprises a tissue type identification of tissues at the distal end portion of the surgical instrument in the region of interest of the living subject.

33. The system ofclaim 32, wherein the physiological condition comprises a volume of suction from the region of interest of the living subject.

34. A method for selectively disabling a surgical instrument operating in a surgical site of a region of interest of a living subject, wherein the surgical instrument has a distal end portion and is operable by a surgeon during a surgery, comprising the steps of:

(a) intra-operatively monitoring a physiological condition of the living subject in the region of interest during the surgery;

(b) determining a variation of the physiological condition of the living subject from an initial state of the living subject in the region of interest, during the surgery; and

(c) generating a signal to disable the surgical instrument when the variation of the physiological condition is greater than a predetermined value, wherein the physiological condition comprises at least one of an electromyogram of electrical activities of muscles of the region of interest of the living subject, a flow rate of blood vessels of the region of interest of the living subject, a temperature of tissues of the region of interest of the living subject, a venous oxygenation saturation and an arterial oxygenation saturation of the region of interest of the living subject, a tissue type identification of tissues at the distal end portion of the surgical instrument in the region of interest of the living subject, and a volume of suction from the region of interest of the living subject.

35-40. (canceled)

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