|
| 
Custom CD of patents similar to US5230338 : Interactive image-guided surgical system for displaying images
corresponding to the placement of a surgical tool or the like - $19.95 |
| United States Patent | 5230338 |
| Link to this page | http://www.wikipatents.com/5230338.html |
| Inventor(s) | Allen; George S. (628 Westview Ave., Nashville, TN 37205);
Galloway, Jr.; Robert L. (7736 Indian Springs Dr., Nashville, TN 37221);
Maciunas; Robert J. (6320 Chickering Woods La., Nashville, TN 37215);
Edwards, II; Charles A. (2316 Erin La., Nashville, TN 37221);
Zink; Martin R. (1044 Berwick Trail, Madison, TN 37195) |
| Abstract | An interactive system for guiding the use of a surgical tool uses at least
one imaging technique, such as CT scanning. A mechanical arm has a fixed
base at a first end and a tool holder that holds the surgical tool at a
second end. A display displays one or more images from the image space of
a patient's anatomy. A computer is coupled to the display and the
mechanical arm. The computer tracks the location of the surgical tool
through physical space, performs a transforming rotation of the physical
space to the image space, and causes the display to display the location
of the surgical tool within the image space. |
| |
 |
Title Information  |
|
|
| Inventor |
Allen; George S. (628 Westview Ave., Nashville, TN 37205);
Galloway, Jr.; Robert L. (7736 Indian Springs Dr., Nashville, TN 37221);
Maciunas; Robert J. (6320 Chickering Woods La., Nashville, TN 37215);
Edwards, II; Charles A. (2316 Erin La., Nashville, TN 37221);
Zink; Martin R. (1044 Berwick Trail, Madison, TN 37195) |
|
|
|
| Publication Date |
July 27, 1993 |
|
|
|
|
|
| Filing Date |
April 22, 1992 |
|
|
|
|
|
|
|
|
|
|
|
| Parent Case |
This application is a continuation of application Ser. No. 07/433,347,
filed on Nov. 8, 1989, now abandoned, which is a continuation-in-part of
U.S. Ser. No. 07/119,353 of Nov. 10, 1987, now U.S. Pat. No. 4,881,579. |
|
|
|
|
|
|
|
|
|
|
 |
|
 |
Title Information |
|
|
|
Description |
|
|
FIELD OF THE INVENTION
The present invention relates to a system for guiding a surgeon
interactively through a surgical procedure, and more particularly to an
integrated system of hardware and software which allows for the intuitive
use of imaging-derived data regarding a patient's anatomy in order to
guide a surgeon through a surgical procedure.
BACKGROUND OF THE INVENTION
There are a number of well-known diagnostic imaging techniques that allow a
physician to obtain high fidelity views of the human body. Imaging systems
which provide cross-sectional (tomographic) views of anatomical structure
without invasive procedures include computed tomography (CT) x-ray imagers
and magnetic resonance (MR) imagers.
A problem associated with the scanning techniques is that each imaging
process is sensitive to the patient's position within the imaging device.
Therefore, each set of images has a discrete, unique orientation. Thus,
images formed from the same modality at different times and images formed
at essentially the same time, but from different imaging modalities (for
example, CT and MRI) cannot be compared on a point-by-point basis. This
prevents accurate comparison of regions within the images.
A surgeon also deals with orientation differences to the imaging space. For
example, although a neurosurgeon will know where his surgical tool is with
regards to certain anatomic landmarks he may not know with the desired
precision where the tool is with regards to the lesion visible on the
images. There have been attempts to solve this problem by temporary
attachment of a relatively large brace-like structure surgically attached
to portions of the body, such as the head. By orienting a surgical tool
with respect to this structure, and by knowing the location of internal
anatomical areas of interest with relation to this attached structure, the
position of the surgical tool with respect to the anatomical areas of
interest will be known.
A problem with these structures is their size and their interference with
normal daily activities, such as sleeping. The structures are therefore
not used over a long period of time (e.g. for more than 12 hours) so that
a comparison of images, or the location of a specific point within the
anatomy, taken over a substantial time period is not practical.
There is therefore a need for an interactive system which will guide a
surgeon in the manipulation of a surgical tool to an exact location that
is specified by an imaging system.
SUMMARY OF THE INVENTION
This and other needs are satisfied by the present invention which provides
an arrangement for an interactive image-guided surgical system. The system
according to the present invention defines an internal coordinate system
within the anatomy of a patient. The internal coordinate system is located
with respect to an external coordinate system, for example, by locating
the end tip of a surgical tool with a known reference point in the
internal coordinate system. Once the position of the internal coordinate
system is known with respect to the external coordinate system, the
surgical tool can be moved anywhere within either the external or internal
coordinate systems and its location will be known with a high amount of
precision.
The present invention also relates to an arm that a surgical tool is
attached to for use in an image-guided system. The arm carries position
encoders so that as the arm is moved, the location of the surgical tool
that is attached to the arm will always be known with respect to the
internal coordinate system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B illustrate different views of a head having fiducial
implants located in the head.
FIG. 2 shows an operating arrangement in accordance with an embodiment of
the present invention.
FIG. 3 shows a mechanical arm constructed in accordance with an embodiment
of the present invention.
FIG. 4 shows an enlarged view of gear engagement for an optical encoder
used with the arm of FIG. 3.
FIG. 5 is a flow chart for an interactive, image-guided surgical system in
accordance with an embodiment of the present invention.
FIG. 6 is a flow chart of the pre-operative software.
FIG. 7 is a flow chart of the first function of the pre-operative software.
FIG. 8 is a flow chart of the second function of the pre-operative
software.
FIG. 9 is a flow chart of a third function of the pre-operative software.
FIG. 10 is a flow chart of the fourth and fifth functions of the
pre-operative software.
FIG. 11 is a flow chart of the sixth function of the pre-operative
software.
FIG. 12 is a flow chart showing the selection of functions in the
intra-operative software.
FIG. 13 is a flow chart of the first function in the intra-operative
software.
FIG. 14 is a flow chart of the second function of the intra-operative
software.
FIG. 15 is a flow chart of the fourth function of the intra-operative
software.
FIG. 16 is a flow chart of the fifth function of the intra-operative
software.
DETAILED DESCRIPTION
The present invention defines a three-dimensional internal coordinate
system that is fixed within a human anatomy. The internal coordinate
system is established within the anatomy using the present invention by
affixing three or more fiducial implants to portions of the anatomy. The
fiducial implants are affixed to points which will not change their
spatial relationship to one another over a relatively long period of time,
such as a few months.
An example of placement of fiducial implants in the anatomy are shown in
FIGS. 1A and 1B. In these drawings, fiducial implants 10A,10B,10C are
implanted in three separate, spaced locations within a skull 18.
Since these three fiducial implants 10A-C are arranged in a noncollinear
manner, a plane is formed which contains these fiducial implants 10A-C.
Once a plane is defined, a three-dimensional coordinate system is defined.
Any point within the body will be within the internal coordinate system.
Although fiducial implants are shown, any three points that are affixed
with respect to the region of interest can comprise the three points used
to define the internal coordinate system. However, fiducial implants 10A-C
that are identifiable and measurable by different imaging systems, such as
CT imagers and MRI imagers, are preferred. The fiducial implants 10A-C can
be relatively small and unobtrusive so that no discomfort or
self-consciousness will be experienced by the patient even though the
patient may carry the implants 10A-C for a relatively long period of time.
A scan, using a known imaging technique, is performed once a patient has
the three fiducial implants 10A-C implanted. An internal coordinate system
will then be defined with respect to these three fiducial implants 10A-C.
During subsequent scans, whether after a few minutes or a few months, the
patient's orientation may change relative to the imaging apparatus.
However, using the present invention, this new orientation can be measured
by locating the fiducial implants 10A-C in relation to the imaging
apparatus and comparing their locations to the previously recorded
locations. This comparison technique permits re-orienting images of
subsequent scans to a position corresponding to the earlier recorded scan
so that equivalent image slices can be compared.
Regardless of the reason why the patient is oriented differently, by taking
advantage of the fixed, fully-defined internal coordinate system in the
anatomy, the location and direction of the plane defined by the three
fiducial implants 10A-C in the first imaging session can be compared with
the location and direction of the same plane defined by the three fiducial
implants at the time of the second imaging session. The cartesian systems
are aligned by three independent rotations. The translation of one
cartesian coordinate system to another is a well-known technique and
readily performable by modern computers. An example of an arrangement
which defines an internal coordinate system for the anatomy and performs a
transformation with respect to rotation from one cartesian coordinate
system to another is described in U.S. patent application 119,353 filed on
Nov. 10, 1987 for a "Method and Apparatus for Imaging the Anatomy", and is
herein expressly incorporated by reference.
Once the internal coordinate system is established, an external coordinate
system is also thereby established by the three noncollinear fiducial
implants 10A-C. In order to keep track of a moving point in both the
internal and the external coordinate systems, it is merely necessary for
the system to initially establish the location of that point with respect
to a point in the internal coordinate system and then continuously follow
the movement of the point in the external coordinate system. As an
example, assume that the point in the external coordinate system is the
end tip of a laser. In order to keep track of the location of that end tip
in both the external and internal coordinate systems, the end tip of the
laser is first brought into a known relationship with one of the fiducial
implants 10A-C, for example touching the implant, and the computer notes
this initialization. The computer used with the imaging system then
follows the location of the end tip as the laser is moved anywhere within
the internal and external coordinate systems. A positioning encoder tracks
the position of the end tip and feeds signals relating the movement of the
end tip within the coordinate systems to the computer. Since the original
position of the end tip (i.e. against the fiducial implant 10A-C) is
known, and its movements have been continuously tracked and fed to the
computer since the original position of the end tip was entered into the
computer, the position of the end tip in either the internal or external
coordinate systems will be known at all times.
FIG. 2 shows a schematic illustration of an operating environment according
to an embodiment of the present invention. In this figure, a patient has
fiducial implants 10 A-C implanted in the skull 18. An imager 102 operates
as described earlier in conjunction with a programmable computer 104. An
operator control panel 11? is coupled to the programmable computer 104, as
is a display 108 which includes a target display 112 that displays the
coordinates of a target (used in radiation therapy applications).
An external arm 34 is fixed to a base 36. The arm 34 carries a tool 38
which is changeable, and can be for example, a laser or any of a number of
surgical tools, such as a pointer, ultrasound unit, biopsy probe,
radiation beam collimator, etc. The arm 34 has a number of joints 42,
although only one is shown for purposes of illustration in FIG. 2. The
movement of the arm 34 is tracked by computer 104 so that the position of
the tool 38 relative to the base 36 of the arm 34 will always be known.
The movement of the tool 38 through the external and internal coordinate
systems (with reference to the base 36 of the external coordinate system)
will be known precisely using the following method.
At the end tip 39 of the tool 38 a sensor 40 may be located. The sensor 40
can be a metal detector or an ultrasonic detector, or any instrument that
can sense the position of a fiducial implant 10 A-C in the patient. If the
fiducial implants 10 A-C are placed in the skull 18, the sensor 40 at the
end tip 39 of the tool 38 is moved by the arm 34, under the guidance of
the surgeon, until it contacts a fiducial implant 10 in the skull 18. This
contact of the end tip 39 with the fiducial implant 10 is noted by the
computer so that the initial position of the end tip 39 relative to the
internal coordinate system is known. Furthermore, since the position of
the end tip 39 relative to the base 36 in the external coordinate system
is also always tracked and known, the position of the end tip 39 can be
followed through both external and internal coordinate systems following
the initialization of placing the end tip 39 into contact with the
fiducial implant 10.
The means to track the arm 34 is well known and is accomplished by sensors
(not shown in FIG. 2) in various locations of the arm 34, detecting either
rotation or movement of the joints 42 of the arm 34.
In surgery, the internal coordinate system defined by the three fiducial
implants 10A-C allow, for example, a laser to be followed as it cuts
through tissue to a tumor. The imaging system 102 used in the imaging
procedure is positioned to continually take imaging data that is provided
to the computer 104 and the display 108 to guide the surgeon who
manipulates the arm 34 and the laser used as the surgical tool 38. As the
laser cuts through the tissue, the change in the tissue will be apparent
in the display 10 of imaging system and can be followed with respect to
the fixed internal coordinate system.
An example of a mechanical arm whose movements can be tracked and which can
hold a variety of surgical tools 38 is shown in FIG. 3. The base 36 of the
arm 34 is movably fixed to some location. The arm 34 has two arm links
40A,40B. The first arm link 40A is coupled to the base by two gimbal
joints 42. The first arm link 40A therefore has two degrees of motion, as
provided by the two gimbal joints 42.
A second arm link 40B is coupled to the first arm link 40A by a second pair
of gimbal joints 42. This second pair of gimbal joints 42 provides the
second arm link 40B with two additional degrees of motion. Relative to the
base 36 of the arm 34, the second arm link 40B therefore has four degrees
of motion.
A tool holder 44 is coupled to the second arm link 40B through a pair of
gimbal joints 42. The tool holder 44 can hold any of a number of different
tools, including a pointer, an ultrasound unit, a surgical laser, a biopsy
probe, a radiation beam collimator, etc. The third pair of gimbal joints
42 provides the tool 38 with two additional degrees of motion, so that
relative to the base 36, the tool 38 has six degrees of motion.
The exact positioning of the tool 38 relative to the base 36 is kept track
of by optical encoders 46. One optical encoder 46 is assigned to each
gimbal joint 42. As an individual gimbal joint 42 is rotated around its
pivot, the optical encoder 46 determines the precise amount of rotation of
the gimbal joint 42 around its pivot. The information from each of the six
optical encoders 46 is provided to the programmable computer 104, which
can therefore precisely track the movement of the tool 38 relative to the
base 36 by keeping track of the individual rotations of the gimbal joints
42 around their pivots.
As can be seen in the embodiment of FIG. 3, the optical encoders 46 are of
a size such that they can be arranged within the gimbal joint 42. This
makes for a very compact arm structure and accurate encoding of the
position of the gimbal joint 42. The entire arm structure 34 is
sterilizable and can be made out of stainless steel, for example.
Furthermore, in order to make the arm 34 easy to manipulate and use, the
arm 34 is counterbalanced in a conventional manner.
Although other means of measuring and feeding back information as to the
pivoting or tilting of the gimbal joints 42 can be used, an optical
encoder such as commercially available and produced by Heidenhain or by
ITEK are suitable. As mentioned before, it is advantageous that the
optical encoders 46 are of a size that fits within the gimbal joints.
A detail of the mounting of an optical encoder 46 is shown in FIG. 4. A
gear 50 that is coupled to the gimbal joint 42 meshes at an angle of
approximate 6.degree. to the gear 52 that drives the optical encoder 46.
This angled meshing prevents backlash of the gears so that the accuracy of
the readout of the optical encoder is ensured.
During an operation, three separate raster images and a graphic image are
displayed on the video display 108 simultaneously to assure the surgeon of
accurate spatial orientation. Each different raster image can be supplied
by a different type of imaging technology. For example, the three
different raster images supplied simultaneously on the video display
screen 108 can be from three different imaging modalities such as CT, MRI,
etc. Alternatively, multiple slices from a single imaging modality can be
displayed simultaneously instead of the same slice from different imaging
modalities. A feature of the present invention provides that the
displaying of the images is performed in real-time, so that the image
slices change as the surgeon moves the arm 34 during surgery.
Although the arm 34 has been described as being usable with the fiducial
implants 10A-C, the arm 34 also can be used with other existing
stereotactic localization systems and frames, as long as an internal
reference point is identifiable. As mentioned earlier, an identifiable
internal reference point is used in order to orient the arm 34 in the
internal and external coordinate systems.
FIGS. 5-16 show various flow charts of the software used in the system of
the present invention. The first software flowchart is shown in FIG. 5 and
depicts an interactive, image-guided surgical system's main program. The
main program begins at start 200 and the graphics board is initialized in
step 201. The mouse is initialized in step 202 and the system defaults are
set in step 203. The patient information is displayed on a screen in step
204 and inputs are provided relating to the patient including the patient
name, and ID number in step 205.
In the decision step 206, it is determined whether the patient is in the
local database. If the patient is in the local database, the patient
information and available image sets are displayed in step 207. At that
point, it is determined (step 208) whether the procedure is the
preoperative of intraoperative procedure. If it is an intraoperative
procedure, the intraoperative software is utilized in step 209.
If the patient is not in the local database, it is determined in decision
step 210 whether this is a new session or not. If it is a new session, the
patient information is collected (step 211) and the preoperative software
is utilized in step 212. If the session is an old session, archival
information is input (step 213) and the archival information is copied
into a local database. The program proceeds from step 207 in which the
patient information and available image sets are displayed. From the
preoperative software 212 and the intraoperative software 209 a decision
step 214 is entered in which it is decided whether or not to process
another patient. If this session is to be ended, step 215 is entered to
end the session. If another patient is to be processed, the procedure
loops back to set system defaults step 203.
The preoperative software of step 212 comprises six major functions. Image
slices that depict a surgical volume of interest are transferred to the
system hard disk. This involves either directly reading them from the
storage media or by transfer from software. Another function is the
displaying of the raster images on the display 108. The third function is
the reviewing of the raster data by position to set separate threshold and
contrast values for all raster images. Once the raster data is in place, a
graphic representation of the raster data is generated in the fourth
function. This representation can be wire-framed or shaded surface or
both. The fifth function of the preoperative software is the editing of
the graphic representation of the raster region. Finally, the physician in
the sixth function may chose to mark regions of interest on the raster
images. These regions are then transferred into the graphic image set. The
flow charts relating to these six functions are shown in FIGS. 6-11.
FIG. 6 shows the overall flow chart of the preoperative software 212. The
first step of the preoperative software 212 is the displaying of the
preoperative menu. The I/O source is selected between using a mouse or
keys in step 215. From the menu, one of the six functions 216-221 are
chosen and performed, or the exit 222 is selected from the menu. From the
exit 222 of the menu, it is determined in decision step 223 whether a
graphic model has been made. If so, there is a return 224 to the patient
information screen on the display 108. If no graphic model has been made,
it is next determined in decision step 225 whether actual scans are on the
disk. If they are not, the image set is transferred in step 226. If the
actual scans are on the disk, a graphic model is made in step 227 and the
patient information screen is returned to.
FIG. 7 illustrates the flow chart for the first function, the step of
adding image sets 216. In step 228, the image data is transferred. In
decision step 230, it is determined whether the images are registered. If
they are not registered, a storage tape is loaded (step 232) and if the
images are registered, a network transfer is performed in step 234. From
either step 232 or 234, an image header is scanned in step 236 to
determine the image type, the number, the orientation etc. The header
information is displayed on display 108 in step 238. In step 239, the I/O
source is selected between mouse or keys. In step 240, the scanned data
for the new header is extracted. Scan sets are extracted in step 241,
these scanned sets being ordered in step 242. The scanned sets are
compressed to byte width in step 243 and are stored in a local database in
step 244. In step 245 a decision is made whether to operate on another
image set at which time the first function 216 is either exited 246 or
returned back to step 228.
FIG. 8 shows the second function in the preoperative software, the display
image set function 217. The first step of this second function is the
provision of the menu to display images in step 248. The I/O source is
selected in step 249. The entire image set can be displayed in step 250
and with input 251, the number of images and size of the images is
determined in step 252. A display with a 256.times.256 image is displayed
in step 253. Alternatively, instead of displaying the entire image set in
step 250, the image set can be displayed in a window in step 254. Based
upon input in step 255, the size of the images is determined in step 256
and the display can be a 512.times.512 in a requested window in step 257.
The second function of displaying image sets 217 is exited in step 258.
FIG. 9 shows a flow chart of the third function, the adjust image display
function 218. Step 260 displays the adjust image menu and step 261 selects
the I/O source. From the menu, the level, width, minimum and maximum of
the gray scale can be adjusted in steps 262-265. After adjustment, gauges
are updated in step 266 and the screen is updated in step 267 with a
return to the menu. Also from the menu, there is a reset step 268 that can
be chosen to restore default values in step 269. Finally, from the menu,
there is an exit 270 from the adjust image display function 218.
FIG. 10 illustrates a flow chart for the fourth and fifth functions, the
making and editing of the graphic model. In step 280, an image set is
input. It is determined in step 281 whether the image set is axial or not.
If it is not, there is a loop until the image set is axial. When the image
set is axial, the gradient difference is used to determine the boundary of
the anatomy of interest, for example the patient's head. In decision step
283, it is determined whether to accept vertices for the image N. If the
vertices are not accepted, a vertex is selected and modified in step 284,
otherwise, this step 284 is skipped to decision step 285 in which all the
images are checked. The image is then incremented to N=N+1 and the flow
loops back to the input of decision step 283 if all the images are not
checked. Otherwise, when all the images are checked as determined in
decision step 285, the fourth and fifth functions 219, 220 are exited in
step 286.
The sixth function, the marking of the region 221 is shown as a flow chart
in FIG. 11. In 290, a target solid is started. Step 291 involves the
selection of a window as an input to the software. The process is binded
to the selected window in step 292 and a line is drawn with the mouse in
step 293. The line is encoded in step 294 with all the windows having
equivalent slices. The input mouse button status is determined in step
295. If the left button is selected, there is a loop back to decision step
293. If the middle button is selected the process loops back to the input
step 292. Finally, if the right button is selected, the outline is closed
in step 297 and the target solid is included in step 298. It is determined
in step 299 whet | | |
