Patent Application
20120022357
The present invention relates to apparatuses and methods for imaging while performing medical procedures along a particular alignment. More specifically, the present invention relates to imaging systems that allow accurate imaging of a procedure as it is being performed when an alignment axis of an emitter is not orthogonal to a planar detector.
Imaging systems are utilized for various applications in the medical field as well as non-medical applications. For example, medical imaging systems include general radiological, mammography, X-ray C-arm, tomosynthesis, ultrasound and computed tomography imaging systems. These imaging systems, with their different respective topologies, are used to create images or views of a region of a patient.
Modern medical imaging systems have become a valuable tool in the healthcare profession. Many imaging systems which were once found only in major medical facilities have become more commonplace due to their affordable cost and compact size. Mobile imaging systems are utilized outside of imaging-specific rooms because of their ability to be transported to operating rooms or other areas serving multiple purposes, thus providing instant on-the-spot imaging.
As a result, real-time imaging is increasingly being required by medical procedures. For example, many electro-physiologic cardiac procedures, peripheral vascular procedures, percutaneous transluminal catheter angioplasty procedures, urological procedures, and orthopedic procedures utilize real-time imaging. In addition, modern medical procedures often require the use of instruments that are inserted into the human body. These medical procedures often require the ability to discern the exact location of instruments that are inserted within the human body, often in conjunction with an accurate image of the surrounding body through the use of imaging.
It would be desirable to provide a directed imaging system designed to replace existing methods for imaging during medical procedures with a faster and more accurate system in situations where an alignment axis of an emitter is not orthogonal to a planar detector.
Improved methods and apparatuses for imaging during medical procedures in accordance with various embodiments of the present invention include use of an image correction algorithm. In various embodiments, an original image of a region of interest where a medical procedure occurring along a particular axis will be performed is created with a beam emitter and a generally planar detector. Due to the emitter not being aligned orthogonal to the detector, the original image will be skewed. Using a known location and orientation of the detector, a location and orientation of the emitter provided by a position monitoring system, and the original image, a processing system can execute the image correction algorithm to provide a corrected image to allow a surgeon to perform the medical procedure while viewing an accurate corrected image in real-time.
In one embodiment, a system for performing a medical procedure on a patient utilizes an image correction algorithm. The system can include a manually positionable beam emitter including an actuator for performing the medical procedure along a particular axis. A generally planar detector can detect the beam from the emitter and generate an original image of a region of interest between the emitter and detector. A position monitoring system can monitor a position and orientation of the emitter. A processor operably connected to the position monitoring system and the detector can execute an image correction algorithm operable to provide a corrected image from the original image due to the original image being skewed as a result of the emitter being aligned along the axis of operation rather than perpendicular to the detector. A video display can display the corrected image in real-time to a surgeon performing the medical procedure on the patient.
In another embodiment, a method includes providing a system for performing a medical procedure on a patient. The system can include a manually positionable beam emitter including an actuator, a generally planar detector that detects the beam from the emitter, a position monitoring system that monitors a position and orientation of the emitter, a processor that executes an image correction algorithm and a video display. The method can further include instructions for performing the medical procedure on the patient. The instructions can include manually positioning the emitter in more than three degrees of freedom along an axis of operation of the actuator at an angle that is not perpendicular to the detector to obtain an original image of a region of interest, which results in the original image being skewed. The instructions further comprise viewing a corrected image of the region of interest on the video display that results from application of the image-correction algorithm to the skewed original image and performing the medical procedure with the actuator while utilizing the corrected image in real-time to assist during the medical procedure.
The above summary of the various embodiments of the invention is not intended to describe each illustrated embodiment or every implementation of the invention. This summary represents a simplified overview of certain aspects of the invention to facilitate a basic understanding of the invention and is not intended to identify key or critical elements of the invention or delineate the scope of the invention.
The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
In the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, one skilled in the art will recognize that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as to not unnecessarily obscure aspects of the present invention.
Referring to
The detector 102 is placed beneath/opposite the patient in the area of interest, i.e., the area where the medical procedure is performed. In one embodiment, detector 102 is a flat-panel detector mounted beneath a patient table and on an X/Y movable stage allowing it to be positioned under the area of interest of the patient as needed. Such modern flat-panel detectors are advantageous in that they are light weight, can run high frame-rates, use fewer parts and can provide an immediate digital image. Various flat-panel detectors that can be used with embodiments of the present invention are manufactured by Varian Medical Systems of Palo Alto, Calif.
In one embodiment, detector 102 should provide at least near real-time feedback to the surgeon. In this embodiment, detector 102 can acquire images at a frame rate of at least 15 frames per second. It has been observed that at rates of higher than 25 frames per second it is difficult to discern meaningful differences in detected images as a result of such higher rates, so a range of frame rates of 15 frames per second to 25 frames per second is preferred. Ideally, the system 100 uses the largest flat-panel detector 102 that can provide such a response time in the desired range of frame rates. In one embodiment, such response times can be provided by a 16″ by 12″ detector 102.
The emitter 104 can be a handheld emitter gun that can include an imaging source located behind an actuator for performing a medical procedure on a patient. Actuator can include, for example, a drill bit and drive assembly, a cutting tool or cutting blade, a needle or syringe or any other device for performing a medical procedure. In one embodiment, some or all of the elements of the actuator are translucent to the beam of the imaging source so as not to interfere with the emitted beam. In this embodiment, at least the portion of the actuator that is coaxial with an axis of emission of the emitter is translucent. This provides an unobstructed image as the procedure is performed, which allows the surgeon to image the target at the same time as performing the procedure without the need for a separate device. One embodiment of an X-ray translucent drill mechanism, aspects of which can be used in embodiments of the present invention, is disclosed in U.S. Pat. No. 5,013,317 to Cole et al., which is incorporated herein by reference. In another embodiment, the imaging source can be aligned along a parallel axis to the axis of operation of the medical procedure so that the actuator does not interfere with the emitted beam while still being aligned at the same angle.
An emitter 104 in the form of a handheld gun according to an embodiment of the present invention is depicted in
A position monitoring system 106 is used in system 100 because proper visualization of the procedure requires knowing where the emitter 104 is positioned and oriented in space. In some embodiments, the detector 102 does not need to be tracked by the position monitoring system 106 because it maintains a fixed orientation in space after initially being set for the procedure, so its location and orientation are known. In other embodiments, the surgeon can adjust the detector 102 during the procedure, so the location and orientation of the detector 102 can also be monitored.
Position monitoring system 106 must be compatible with the nearby imaging source, tolerant of significant metal in the environment, and have high reliability and accuracy. In some embodiments, position monitoring system 106 can be an optical tracking system, such as manufactured by Ascension Technology Corporation of Milton, Vt. In other embodiments, position monitoring system 106 can be a kinematic/mechanical tracking via an arm or linkage. In such an embodiment, the emitter/gun can be attached to a manually positionable arm anchored to a ceiling, wall or floor of an operating room or a movable base in the operating room. In other embodiments, position monitoring system can use radio-frequency identification, image analysis using infrared light or other wireless tracking/sensing. In some embodiments, some or all of position monitoring system 106 can be incorporated into emitter 104 rather than being a separate system. In such embodiments, position monitoring system 106 can use one or more of accelerometers, gravitometers, magnetometers, and global positioning systems to track and/or sense the location and orientation of emitter 104. Position monitoring system 106 can allow the emitter to be positionable, and track the positioning of the emitter, in at least three degrees of freedom. In some embodiments, the emitter can be positionable in five or six degrees of freedom. In one embodiment, emitter can be lockable to prevent movement in one or more degrees of freedom for all or part of the procedure, such as only allowing the emitter to be moved along the axis of operation once proper alignment has been obtained.
Tracking the emitter's 104 location and orientation relative to the detector 102 and imaged area allows the use of a perspective image correction algorithm to eliminate the need to keep the gun 104 perpendicular to the detector 102, giving the surgeon a great deal of freedom of movement in performing the procedure. This is desirable because often a required axis or alignment of the procedure relative to the patient's body is not aligned perpendicular to the detector. If the procedure requires the emitter 104 to be aligned relative to the patient in a way that causes it to be at angle to the detector 102, a skewed image is detected and generated by the detector. Use of an image correction algorithm allows the surgeon to align the gun 104 at an angle to the detector 102 that is properly aligned with the patient for performing the procedure while visualizing an accurate image of the target area of the patient.
The image correction algorithm 108 therefore allows the emitter 104 to be used in alignments that are not orthogonal to the detector 102 when the emitter 104 is being used to image the area of interest 112 of a patient on a patient table 114, as depicted in
In one embodiment as shown in
Standard texture coordinates ranging from 0 to 1 can then be assigned to the four corner points at step 142. Texture coordinates (or UV coordinates) are a tool used to linearly map a two-dimensional image onto a three-dimensional object in space. These coordinates, usually represented as u and v, are assigned across an image, ranging from 0 to 1 in each direction. Each vertex of the three-dimensional object is assigned a u and v coordinate indicating which part of the two-dimensional image is associated with that vertex. Since the detector plate is rectangular and is covered by the detected image, the four corners (or vertices) of the detector map correspond to the four corners of the detected image. These four texture coordinates are packed into a texture matrix T.
By treating the emitter 104 as something of an imaginary camera, a perspective transformation for the field of view (“fov”) onto the detector 102 can be defined using a standard perspective transform matrix at step 144. Preferably, the fov is computed to be just large enough to view the whole detector plate from the emitter's location. In most applications, a field of view of 45 degrees is sufficient. A perspective transform matrix alters the shape of a given geometry to match the view of that geometry from a defined location. It adds perspective to the resulting image, such as by causing portions of the geometry that are further away to be smaller. This mimics the view as would be seen by the human eye from the defined location.
Where h=tan(fov/2) and far and near are the distances to the far and near view planes. For optimal viewing, near is set at 1 and far is the distance between the emitter 104 and the furthest corner of the detector 102. Next, the gun/emitter transform matrix G (obtained from the position monitoring system) can be used to bring the detector 102 corners into the image of the imaginary camera, C*, at step 146.
C*=PGC
Finally, the corrected image is obtained at step 148 by rasterizing the image space corners C* as a quadrilateral textured with the original detector image, by interpolating according to the texture coordinates. Rasterization is a standard computer graphics algorithm, which is known to those skilled in the art. Rasterization, also known as scan conversion, is the process of rendering a three-dimensional shape or scene onto a flat two-dimensional surface, usually so it can be viewed on a monitor. Rasterization is used as part of the image correction algorithm 108 to render the transformed detector plate object (textured with its detected image) into the view space of the imaginary camera located at the gun/emitter. This yields the corrected image. In one embodiment, the image correction algorithm is performed by a desktop or laptop computer. In other embodiments, the algorithm can be performed by a processor within the emitter 104 or detector 102 or associated with the monitor or display 110. In one embodiment, the algorithm continuously runs during the operation to provide a continuous real-time corrected image that continually adjusts for movements of the emitter 104, detector 102 or region of interest to show the actual appearance of the region in real-time.
CorrectedImage=Rasterize(C*,T,OriginalImage)
By defining the field of view and near/far planes as described herein, a minimum of information is lost during the image correction process. No scaling is required to obtain a properly sized corrected image. The entire process can also be implemented using modern graphics hardware. Corrected images can therefore be processed at extremely high frame rates on the order of hundreds of times per second even for large images.
Referring now to
The monitor 110 need only be safe for use in an operating room and large enough to be easily observed by a surgeon while performing an operation. The monitor must be sterile if located within the sterile field of the procedure. If the monitor is not within the sterile field, it will not have to be sterile but will have to be larger than a monitor within the sterile field in order to be viewable from within the sterile field. In one embodiment, the display can be part of the emitter gun, such as a video screen located on a proximal end of the gun.
Beam emitter 104 and detector 102 can incorporate various imaging systems that can be employed in embodiments of the above described system 100. Beam emitter 104 and detector 102 can relate to any type of imaging system that emits a beam that is captured by a detector to generate an image. In one embodiment, imaging system is an X-ray imaging system with an emitter 104 including an X-ray source having an X-ray tube having an anode, a cathode and a power source, and an X-ray detector. In another embodiment, imaging system is a terahertz imaging system having a source emitting electromagnetic waves in the terahertz range and a cooperating detector. In a further embodiment, the source can provide ultrasonic waves for an ultrasound-based imaging system. In another embodiment, system can utilize magnetic resonance imaging, wherein the magnetic source is located inside the emitter gun.
Imaging and alignment systems as described herein can be used with a number of medical procedures. Various procedures that can advantageously utilize such a system will be described below. However, the procedures described herein are illustrative and are not limiting. System can be used with any medical procedure that would benefit from the use of imaging. In addition, imaging/alignment systems as described herein can be employed in non-medical applications. System can be utilized in any non-medical application that utilizes imaging, such as, for example, airport screening. In such embodiments, system can optionally be provided with various safety features to prevent human exposure to the beam, such as not allowing the emitter to emit a beam when it is not aimed at the detector and ceasing emission if it is detected that human tissue or bone is within the imaging field. In one embodiment, image recognition can be employed to detect whether safety features should be invoked.
In one embodiment, imaging system is used to insert pedicle screws into a spine of a patient. Emitter gun can be equipped with a drill bit and drive assembly for inserting the screws into the pedicle and optionally drilling pilot holes into the pedicles prior to insertion. In pedicle screw insertion, it is key to align the screws axially down the pedicle. However, the pedicles are often not aligned perpendicular to the detector and each pedicle may have a different alignment. Use of imaging system allows an accurate image of each pedicle to allow the screws to be properly placed axially along the pedicles.
In another embodiment, imaging system can be used to aid in performing needle biopsies. The actuator in such a system can be be a needle, which can be translucent. Imaging system allows the surgeon to view an accurate real-time image of where the needle is positioned to ensure that the biopsy is taken in the proper area. In one embodiment, the biopsy procedure can be a bone biopsy.
In a further embodiment, imaging system can assist vertebroplasty and kyphoplasty procedures. Vertebroplasty uses a hollow needle to inject bone cement into fractured, crushed or otherwise weakened vertebrae to provide support and treat pain. In kyphoplasty, a balloon is first inserted into the area through a needle and expanded in the fracture and then bone cement is inserted into the balloon with the needle. Imaging system can be used to properly guide the process with a needle as the actuator for inserting the bone cement and/or balloon.
A number of bones in the body can have fractures repaired using intramedullary rods. A hole is drilled down the long axis of the bone and a rod is then driven into the cavity to align the bones and promote healing. The rods can then be locked by drilling screws orthogonally into the rod to prevent collapse or rotation. An imaging system as described herein can aid in proper alignment and placement of one or more of the rod or the locking screws.
In another embodiment, imaging system can be used with a pelvic fixation procedure. Pelvic fixation is a difficult procedure involving the placement of plates and/or screws to hold together portions of a fractured pelvis. The enhanced imaging of imaging system could be advantageously used to drill holes in the proper locations and insert the screws to ensure that the screws properly engage the complicated structure of the pelvic bones.
In a further embodiment, imaging system can be used to aid in resecting bones, such as knee bones. Emitter could be equipped with a saw blade, milling tool, or other device for removing bone. The system could then be used to enhance the visualization of a minimally invasive procedure to ensure that the bone is resected at the proper angle and depth.
In one embodiment, a second emitter and detector plate can be utilized in the system, which can be positioned at a known offset from those already present in the system. By using this second imaging set to image the same target area, a three-dimensional stereoscopic image of the procedure can be generated. Such an imaging system can provide a sense of depth to the procedure that can allow a surgeon to see, for example, how far a drill has penetrated into a bone or how far a biopsy needle has been inserted. In one embodiment, the separate emitter and detector can be provided by a traditional c-arm device. Alternatively, the second emitter can be a second manually positionable detector as described herein.
In another embodiment, structured infrared light combined with computer scanning can be incorporated into system to provide a topological view of the body's surface. This technology can be incorporated into the emitter gun to produce a combined image that shows transparent surface detail overlaid onto the image of the underlying bone. This also can be used to provide a sense of drill, needle, or other actuator depth to the surgeon.
In a further embodiment, a dye injection or spatter mechanism can be integrated with the emitter gun. The surgeon can then use the gun to inject radiopaque dye ahead of the actuator, allowing a clearer image of the target area where the operation is performed. In one embodiment, this procedure can be used in a target area having soft-tissue that does not normally image well under imaging beam, such as in various biopsy types.
Various embodiments of systems, devices and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the present invention. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, implantation locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the invention.
The present application claims the benefit of U.S. Provisional Application No. 61/328,062, filed Apr. 26, 2010, the disclosure of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61328062 | Apr 2010 | US |
