Surgery – Instruments – Stereotaxic device
Reexamination Certificate
1999-10-27
2001-02-13
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Stereotaxic device
C606S129000, C604S116000, C600S426000, C600S427000
Reexamination Certificate
active
06187018
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the medical diagnostic imaging and surgical arts. It finds particular application in conjunction with image guided surgery (IGS), and will be described with particular reference thereto. However, it is to be appreciated that the present invention is also amenable to other like applications.
Medical diagnostic imaging is a valuable tool for obtaining accurate visualization of a particular patient's internal anatomy and/or pathology in a minimally invasive manner. Prior to a medical procedure, three-dimensional (3D) diagnostic image data of the brain, spinal cord, and/or other anatomy of interest is often generated by computed tomography (CT) scanners, magnetic resonance imaging (MRI) scanners, gamma cameras, and other medical diagnostic imaging equipment. Typically, these imaging modalities provide structural detail with a resolution of a millimeter or better. Reconstructed images of the patients anatomy are then used by medical personnel to aid in navigating through and/or around various anatomical structures during surgery.
Commonly, an IGS system includes a computer, active and/or passive tools carrying infra-red (IR) emitting diodes, a stereoscopic optical tracking system, and a tool interface device. The IR rays emitted by the active tool (or reflected in the case of a passive tool) are detected by charge-coupled device (CCD) cameras mounted on an optical unit. Using the detected IR rays, the system tracks and/or localizes the position and orientation of the tool in a 3D coordinate space which is registered with that of the 3D image data. In this manner, the position and trajectory of a tool relative to imaged anatomy is determined and used to aid in the maneuvering of the tool and/or the placement of a tool guide.
Various frameless stereotactic IGS procedures have been developed which take advantage of the 3D image data of the patient. These procedures include guided-needle biopsies, shunt placements, craniotomies for lesion or tumor resection, total hip replacement (THR) surgery, and the like. Another area of frameless stereotaxy procedures which requires extreme accuracy is spinal surgery, including screw fixation, fracture decompression, and spinal tumor removal.
In spinal screw fixation procedures, for example, surgeons or other medical personnel tap and drill a hole in spinal vertebra into which a screw is to be placed. The surgeon often relies heavily on his own skill in placing and orienting the bit of the surgical drill prior to forming the hole in the vertebra. Success depends largely upon the surgeon's estimation of anatomical location and orientation in the operative field. Unaided, this approach can lead to less than optimal placement of screws which in turn may injure nerves, blood vessels, or the spinal cord.
In THP surgery, the surgeon aligns an implant cup in a pre-planned orientation suing the assistance of the navigation system. The cup is optimally oriented so as to allow a maximum range of motion for the leg (i.e., femur) without impinging on the pelvic bone.
Nevertheless, use of a stereotactic IGS procedure presents certain problems and/or complications of its own. For example, one problem is obtaining the correct positioning of the CCD cameras such that their focus and/or finite field of view (FOV) are optimally located relative to a patient's anatomy of interest. This can be extremely important for some procedures such as, for example, THR wherein the navigation system has to track the movements of two objects (i.e., the pelvis and the femur) with respect to each other. Trackers used to localize these two objects may be as far apart as 1-2 feet, and the navigation system has to be optimally positioned so that both trackers are within the FOV of the system.
Previously developed techniques aimed at achieving a solution to this problem involved complicated software design, and indirect feedback. In turn, only specially trained personnel were qualified to set up the system.
The present invention contemplates a new and improved auto-positioning device which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a detector unit for an image guided surgery system is provided. It includes an adjustable stand having a plurality of receivers mounted thereto such that the detector unit has a defined finite field of view in which it detects radiant energy. It further includes at least one source of radiant energy mounted to the adjustable stand in fixed relation to the receivers. The source projects radiant energy in a pattern to mark a location of the defined field of view.
In accordance with a more limited aspect of the present invention, the at least one source is a light source.
In accordance with a more limited aspect of the present invention, the light source is a laser.
In accordance with a more limited aspect of the present invention, the at least one source of radiant energy includes a plurality of sources.
In accordance with a more limited aspect of the present invention, the sources of radiant energy are arranged such that projected radiant energy therefrom is concentrated at a point in space which coincides with a location in the defined field of view.
In accordance with a more limited aspect of the present invention, the location in the defined field of view is selected from a group consisting of its center and one of its outer boundaries.
In accordance with a more limited aspect of the present invention, the pattern marks at least one dimension of the defined field of view.
In accordance with a more limited aspect of the present invention, the light source includes first and second light sources. The first light source projects a ring of light at a defined distance which marks the location of the defined field of view. The second light source projects a beam of light which intersects the ring of light at the defined distance. At the defined distance, the ring of light has a diameter substantially equal to that of the defined field of view.
In accordance with a more limited aspect of the present invention, the first and second light sources are lasers and the first light source has a refractive element affixed to an output end thereof. The refractive element forms light emitted from the first light source into a substantially conically shaped beam.
In accordance with another aspect of the present invention, a method of positioning a finite field of view of a detector unit for an image guided surgery system is provided. The method includes holding a light reflecting surface at a point in space and projecting a pattern of light from the detector unit toward the light reflecting surface. The pattern of light has a fixed spatial relationship with respect to the detector unit's field of view. Thereafter, the light reflecting surface is viewed, and the detector unit and light reflecting surface are adjusted relative to one another until a desired pattern of light is depicted on the light reflecting surface.
In accordance with a more limited aspect of the present invention, the method further includes determining spatial coordinates for the field of view based upon the light reflecting surface's position.
In accordance with a more limited aspect of the present invention, the step of projecting includes projecting at least two laser beams of light which intersect at a predetermined location relative to the field of view.
In accordance with a more limited aspect of the present invention, the detector unit is adjusted until the intersection coincides with where the light reflecting surface is being held such that a single dot is viewed thereon.
In accordance with a more limited aspect of the present invention, the desired pattern of light viewed on the light reflecting surface coincides with the field of view and has at least one dimension in common therewith.
In accordance with a more limited aspect of the present invention, the light reflecting surface has indicia thereon which correspond to th
Czarkowski Bernard J.
Messner Dale A.
Sanjay-Gopal Sethumadavan
Fay Sharpe Fagan Minnich & McKee LLP
Philogene Pedro
Z-Kat, Inc.
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