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BACKGROUND AND SUMMARY OF THE INVENTION
The use of stereotactic instrumentation based on tomographic imaging is now
common place in surgery, especially in neurosurgery of the brain. Such
methods typically involve attaching a headring apparatus to the patient's
skull and acquiring imaging data that is space related to the headring,
for example, by the utilization of indexing devices, localizer structure
or other fiducial apparatus. Thus, quantitative coordinates of targets
within the patient's head can be specified relative to the fiducial
apparatus. An arc system or other pointing device then can be used to
guide probes or other instruments selectively into the brain
quantitatively based on the imaging data.
Also common place in prior techniques is the acquisition and use of large,
three-dimensional data sets of imaging data that is stored in computer
graphics workstations and visualized on computer graphics screens, such as
cathode ray tube (CRT) screens in an operating room. Computer graphics
data has been used in conjunction with other apparatus. For example,
computer graphics images, based on imaging data have been placed in the
direct view field of a surgical microscope. Specifically, see U.S. Pat.
No. 4,722,056 granted Jan. 26, 1988 to Roberts et al. Also, to some
extent, computer graphic methods have been used with stereotactic arc
systems. For example, the work of Dr. Patrick Kelly (Tumor Stereotaxis)
referred to in the referenced patent to Roberts et al is pertinent in that
regard. Accordingly, a graphic representation of a surgical approach into
the head is displayed on a computer screen based on reconstructed images
of tomographic scan data. Thus, by knowing the quantitative stereotactic
direction into the surgical area, a corresponding graphics display image
can be displayed on a computer screen. Consequently, a surgeon can view a
reconstructed picture of the image he will see upon looking directly into
an actual surgical field, either with a naked eye or through a microscope.
Quantitative maneuvers, such as volumetric resection, can thus be made by
measurements in the actual surgical field, compared to measurements
extracted from the graphic display.
Generally, computer-assisted stereotactic surgery is becoming popular in
neurosurgery. In that regard, examples of various available computer
graphic systems for use in surgery are produced by Radionics/RSI,
Burlington, Mass. A system known as the Compass System is a commercial
product embodying Dr. Kelly's technique as mentioned above. Another
specific implementation of Dr. Kelly's technique involves importing a
reconstructed graphics image into a "heads-up" display, which the surgeon
can see as he views the surgical field directly or through a surgical
microscope. Forms of heads-up displays, using goggles, are common place in
military aircraft applications. Accordingly, a small display can indicate
a computer-reconstructed image of what should be seen in a surgical field.
Thus, the surgeon can view directly the surgical field and make decisions
and quantitative maneuvers in the surgery, based on comparison with the
heads-up display.
Generally, these prior computer-assisted surgical methods have certain
disadvantages. In the screen display apparatus, the surgeon must view the
computer graphics screen, then change his view to the surgical opening.
Accordingly, an inconvenient two-step operation is involved requiring
alternate viewing. In the case of the heads-up displays, (as for example
through a microscope as described by Kelly, stated below) the surgeon is
encumbered by having to wear goggles or visualize only a rudimentary
outline of the target volume.
The Kelly technique imparting an image, based on a computer-generated
target, into visualization of a surgical field, ordinarily involves a
microscope. The technique restricts the target image to a rudimentary
outline and restricts the view line to the target volume. It is also
noteworthy that surgery, while looking at a graphic display (video) is
commonly performed in other fields employing endoscopic techniques,
however, those techniques do not relate a video image to a computer
graphics display.
Generally, the present invention involves stereotactically mounting a video
camera to provide image data. Thus, plural surgical images can be
provided, as for comparison, in a single (or plural) computer graphics
display, one, the surgical view image, the other, a reconstructed image
from graphics data. The surgical view image for the single display may be
accomplished using a minimally invasive, extracorporeal camera located
outside the body near the surgical opening. Thus, in accordance herewith,
the camera structure providing the video (actual image) related to
stereotactic space, in one embodiment, may be minimally obtrusive so that
the surgeon can view into the surgical field directly by naked eye, or by
microscopic view. The surgical view or actual current image is combined in
accordance with one embodiment in a common unitary display with the
reconstructed or reference image processed from computer graphics data.
The comparable images in a single display are enabled by tracking and
correlating the position of the camera to the patient (camera subject).
Thus, for example, by the utilization of stereotactic placement or
registration of camera positions and patient anatomy, effective dual
images (current actual and reference) may be provided in a single display.
For example, a video image may be displayed on a single display means
along with a reconstructed computer graphics image provided from
prescanned or imaged data. Alternatively, the surgical view or actual
current image and the reconstructed or reference image may be provided in
plural displays.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures, which constitute a part of this specification, exemplary
embodiments exhibiting various subjectives and features hereof are set
forth, specifically:
FIG. 1 is a combined perspective and block diagram view showing an
embodiment of the present invention;
FIG. 2 is another combined perspective and block diagram view showing
another embodiment of the present invention; and
FIG. 3 is still another combined perspective and block diagram view showing
still another embodiment of the present invention.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
FIG. 1 shows a patient's head H with a surgical platform or headring
apparatus R fixed to the patient's skull. In such an environment, an
imaging system I receives video and position data to drive a display
apparatus D depicting two surgical views as illustrated. As disclosed in
detail below, an actual current image is displayed along with a reference
view provided from computer graphics data.
Considering the structure of the imaging system I in greater detail, the
headring apparatus R is fixed to the patient's head H by headposts 1
extending upward and somewhat axially parallel from a ring 2 and
terminating at headscrews 3. Generally, the headring apparatus R typifies
well known stereotactic structures involving the utilization of well known
stereotactic reference methods. The headring 2 also carries an adjustable
holder 4 (sometimes referred to as a localizer) which includes an adaptor
5 fitted to receive a small video camera 6. Note that the video camera 6
is positioned to view into the depths of a surgical opening 7 in the
patient's head H.
The video camera 6 is connected by a cable 8 to a video signal processor 9,
which functions in cooperation with the camera 6 to produce a video signal
as well known in the art. The processor 9 is in turn coupled to a video
controller 10 which also receives signals representative of a second
image. However, at this point it is to be understood that as one
component, the controller 10 provides a signal to the display device D for
picturing the camera view, e.g., the image 11 (left).
The video controller 10 may take various forms as well known in the prior
art, for example, as disclosed in the book COMPUTER GRAPHICS: PRINCIPLES
AND PRACTICE, Second Edition, Foley et al., Published by Addison-Wesley
Publishing Company, 1991. Specifically see the description at section 4.4
(page 184). Functionally, the video controller 10 is capable of mixing
signals representative of different images in accordance with desired
formats. In that regard, as indicated above, the video controller 10 also
is connected to receive signals representative of another image from a
frame buffer 12 driven by a display processor 13 utilizing data from a
scan data memory 14. Such elements are well known as described in the
above referenced text on computer graphics. As described in greater detail
below, the computer graphics elements provide a reference image 15 (right)
on the screen 16 of the display device D.
Recapitulating, the screen 16 of the display device displays two images
representative respectively of the tissue currently viewed by the camera 6
(image 11, left) and a stored scan data image (reference image 15, right)
provided from the memory 14. Note that the reference image 15 (scan data)
may be from CT, MRI or other imaging systems and can be provided in
stereotactic space relative to the headring structure R by localizer means
or other techniques as well known in the art. In that regard, functional
apparatus embodying such techniques is available from Radionics,
Burlington, Mass. The imaging data from the memory 14 may take the form of
raw slice data or angiographic planar images that may be put into
stereotactic space relative to the head or ring structure R and the holder
4 and may involve the utilization of "frameless indexing methods" as
reported by Drs. B. Guthrie and J. Adler. For example, such registration
may involve a digitizing arm or other optical or electromechanical
mechanism, as known in the art to register the patient's head H in
relation to the ring structure 2 or land marks on the surface of the
patient's head. Once such referencing has been done, the imaging data from
the memory 14 can be related in space to the patient's head H and any
associated nearby apparatus as the headring 2. Thus, the camera 6 can be
adjusted in space to point at a view that has been visualized
quantitatively or stereotactically in the image scanner database (memory
14). Such is also a form of stereotactic localization.
With the stereotactic data available from the position of the stereotactic
localizer, a computer graphics reference image may be provided indicating
the view expected in the surgical opening 7. Specifically, the image may
take the form of the image 15 as shown in FIG. 1. That reference image,
along with its various visualized structures, would then correspond to
what the surgeon should see at a given depth of penetration into the
surgical opening 7. Thus, by having a direct comparison of the camera
vision view image 11 (current actual) next to the reconstructed surgical
view image 15 (reference), the surgeon is able to make quantitative and
predetermined maneuvers within the opening 7, using instruments that are
placed into the opening knowing what critical structures or target
structures can be anticipated.
Returning to the imaging system I, the scan data memory 14 provides image
data through the display processor 13 to be stored in the frame buffer 12
preliminary to display operations. In that regard, as indicated above,
forms of such structures are well known in the graphics art, specifically,
see the above-referenced text, COMPUTER GRAPHICS: PRINCIPLES AND PRACTICE.
Note that graphic data stored by the memory 14 also may include data for
index marks 17, e.g. azimuthal angle registration designations "0" and
"180" provided for both images 11 and 15.
It may be necessary to exactly register the dimensions of both images so
that they appropriately correspond in size. In that regard, the display
processor 13 along with the video controller 10 afford such capabilities.
Thus, the system hereof affords a view of the combined, simultaneous
images of a camera view with a reconstructed view of the same surgical
opening on a common display device.
With the camera 6 placed as shown in FIG. 1, a surgeon can simply view one
object, namely the screen 16, without being required to look back at the
surgical opening 7 to perform manipulations. For example, a surgeon could
place instruments into the surgical opening 7 while viewing the computer
screen 16 to view the instruments as they appeared in the image 11. By
knowing the depth at which the tools are being manipulated in the surgical
opening, the surgeon could compare image 11 with image 15 for reference. A
full operation could be performed with such a graphics display view. Thus,
the system enables the importation of the surgical field image 11
concurrently with the computer reconstructed image 15.
Turning now to the embodiment of FIG. 2, reference numerals similar to
those above are used for similar components. In that regard, note that the
imaging system I is shown as a combined structure, that is, simply a
single block for processing the signals to drive the display device D.
Generally, the embodiment of FIG. 2 presents a system in accordance
herewith that incorporates a more elaborate head frame R1 and is minimally
obstructive in directly viewing the surgical opening 7. Again, the
headframe R1 is secured to the patient's head H by posts 1 and screws 3.
The unit may comprise a stereotactic arc system as for example in the form
of a commercially available CRW Stereotactic Instrument produced by
Radionics of Burlington, Mass.
An arc 22 of the frame R1 incorporates a probe carrier 23 with the
capability to hold instruments or camera devices aligned with a
predetermined trajectory 24. Mounted on the probe carrier 23 is a tubular
optical system 25 such as is commonly found in endoscopes and which
commonly involve either fiber optic or glass lens carriers. The optical
system 25 is connected to a camera 26 and in that regard, the optical
system 25 can be made of very small diameter so that the degree of
obstruction along the line of sight or trajectory 24 is minimal. A
connection is provided via a cable 27 from the camera 26 to the
computer-graphics and video system I.
An advantage of the embodiment of FIG. 2 is that a surgeon S can view into
the surgical opening 7 via the camera 26 or view directly into the
opening. Thus, the surgeon S has the option of performing machine/vision
procedures exclusively using the visualization images of the display
device D, or alternatively he may look directly into the opening 7.
Optical systems such as the system 25 are common in minimally invasive
surgery inside the body. Such devices are generally known as endoscopes,
and are commonly coupled to cameras. In that regard, endoscopes are always
placed into the body through a surgical wound or orifice. However, the
embodiment of FIG. 2 differs in that the optical system 25 is external to
the body and approximates the opening of the surgical wound 7 so as to
view into the surgical opening 7. Thus, the system could be referred to as
an extracorporeal analog of an endoscope.
There are many structures and devices for viewing the comparative images of
the computer reconstructed data and the video camera. For example, as
depicted in FIG. 2, the computer graphics and video system I mixes the two
sources of image data to provide superimposed or overlapping images.
Specifically, a solid line image 30 represents the actual current image
from the camera 26. A dashed line image 31 represents the computer
graphics image of the same field provided from scanned memory data.
In addition to superimposition, methods of color transparency and wire
frame displays also are well known in computer graphics and could be
utilized to enhance images in various formats. Thus, in accordance with
various techniques of the art, the two images (images 11 and 15, FIG. 1
and images 30 an 31, FIG. 2) might be variously implemented and displayed.
Specifically, for example, liquid crystal displays may be employed.
Turning now to FIG. 3, it will be noted that similar reference numerals are
again utilized to identify similar components and, again, the computer
graphics and video system I (FIG. 1) is represented by a single block.
Generally, in the system of FIG. 3, a surgical microscope is incorporated
with camera structure in a composite microscope structure M. The composite
structure M is utilized and positionally tracked so as to provide both a
camera view and a microscopic view by the surgeon S into the surgical
opening 7.
Considering the system of FIG. 3 in somewhat greater detail, the microscope
structure M may be variously supported with or without direct reference to
the patient's head H. In that regard, a support structure is represented
by a block S with dashed lines 33 and 34 extending respectively to the
patient's head H and the microscope structure M.
In the system of FIG. 3, the position of the microscope structure M is
tracked without the requirement of a physical connection to the patient's
head H; however, various devices may be employed as the support structure
S and in that regard, the mounting could be on the patient's head H as
described with respect to FIGS. 1 and 2. However, in the embodiment of
FIG. 3, the position of the microscope structure M is tracked by optical
sensing as generally known in the art.
Considering the microscope structure M in greater detail, a housing 34
contains optical elements and supports external apparatus. Specifically, a
pair of light emitting diodes 38 and 40 (as shown mounted at the upper end
of the housing 34 in FIG. 3) are externally mounted to be viewed by
stationary cameras 42, 43, and 44. Consequently, as generally indicated by
ray lines 46, each of the cameras 42, 43 and 44 receives infrared
radiation from which a determination is made as to the position and
orientation of the light emitting diodes 38 and 40, and accordingly, the
position and orientation of the microscope structure M. Each of the
stationary cameras 42, 43 and 44 is connected to a tracking unit 48, which
provides a reference signal to the computer graphics and video system I.
In that regard, the cameras 42, 43, and 44 along with the tracking unit 48
may take the form of a commercial implementation known as Pixys' of
Nothern Digital tracking system, available from Pixys Inc., located at
Boulder, Colo., USA. Thus, the microscope structure M may be registered
with reference to the patient's head H. That is, by tracking the position
of the microscope structure M and referencing it to the patient's head H,
stereotactic operation is accomplished. Specifically, the microscope
structure M may be referenced to the patient's head by sequentially
focusing it on physical markers 50, 51, and 52 borne on the patient's head
H. Thus, by registering the microscope structure M with respect to the
patient's head H and tracking it, the resulting data, indicating position
and orientation relative to the patient's head, enables the formulation of
computer graphics data as described above.
As suggested above, independent of the displayed images, the surgeon S may
view the surgical opening 7 directly through the microscope M. In that
regard, gazing through the optical viewing ports 55 and 56, the surgeon's
lines of sight pass through a pair of beam splitters 58 and 60 to the
surgical opening 7. Alternative to such a direct view, consider now the
provision of the displayed images as described with reference to earlier
embodiments.
The housing 34 carries a pair of video cameras 61 and 62 mounted to view
the surgical opening 7 as a reflected image from the beam splitters 58 and
60. Accordingly, the beam splitters enable the cameras 61 and 62 to "look"
down the field of the microscope, just as the optical viewing ports 55 and
56 do for the visualization by the surgeon S. Thus, the same view that the
surgeon would observe is received by the video cameras 61 and 62 which may
provide representative signals for a stereoscopic (three dimensional) view
of the surgical scene, e.g., the surgical opening 7.
With the position of the microscope structure M known in relation to the
patient's head H, stereotactic coordination or mapping is accomplished as
explained above. In that regard, data signals from the cameras 61 and 62
are provided to the computer graphics and video system I for processing to
accomplish actual and reference images on the screen 16 of the display
unit D. In that regard, the resulting images 70 and 71 may be
substantially as previously described; however, in the embodiment of FIG.
3, the image 70 may be stereo optical as indicated above. That is, the
image 70 is a video representation of one or both of the camera views from
the cameras 61 and 62. Accordingly, various stereooptic techniques may be
employed. For example, an alternating flicker view between the cameras 61
and 62 may be provided in synchronism with a viewing device 77 worn by the
viewer V to perceive a three-dimensional image. That is, the viewer V
wears the viewing device 77 incorporating a pair of eye pieces 75
functioning as synchronized shutters to attain a three dimensional image
as well known in the art.
In the display of the screen 16, adjacent images (video image 70, the
graphic image 71) are presented. The display is provided by processed
signals from the computer graphics and video system I. Data for the
graphic image 71 may be developed from stored image information or taken
directly from an imaging machine by the utilization of a transfer device
as indicated above. Of course, the images 70 and 71 also may be viewed in
a non-3D fashion as well if desired and as explained above.
It will be apparent that the surgeon S may look at the computer screen 16
(viewer V) and see the same field of view or a similar field of view that
he could view through the microscope structure M. In that regard, as
explained above, alternatives include the possibility of utilizing tiny
cameras that view into the surgical opening 7 and enable the surgeon to
simultaneously view the surgical opening 7 by means of binocular eye
pieces or perhaps a standard surgical microscope.
As indicated in FIG. 3, image data also may be sent to separate display
units D2 and D3 for providing other displays of images 76a, 77b and 78.
Again, these images may be variously formed and constituted. In that
regard, the display units D2 and D3 may take the form of very large CRT
monitors near a surgical scene or could be smaller monitors mounted near
the surgeon or worn by a surgeon as the device 77 coupled to the display
unit.
The various displays could be imported even into the microscope itself and
viewed with beam splitter structures. Alternatively, the various displays
could be imported into commercially available heads-up displays or goggle
displays. To further indicate variations, combinations of microscopes,
optical viewers, cameras and multiplicities thereof of each of these can
be invoked to produce three-dimensional, single-dimensional, or
comparative views.
A variety of imaging devices and image scan apparatus can be used to
accumulate image data, including CT, MRI, ultrasound, PET scanning, 2-D
and/or dynamic angiographic or planar X-ray structures, rendered either in
two dimensions or three dimensions. A variety of graphics display
structure also may be used including cathode ray tube apparatus, along
with 2-D and 3-D viewing methodologies, eye pieces, glasses, etc. Many
other implementations of cameras, video mixing and assimilation and
three-dimensional computer graphics representation of anatomy may be
devised by those skilled in the art.
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