U.S. patent application number 11/646994 was filed with the patent office on 2007-08-02 for method and system for calibrating a surgical tool and adapter therefor.
This patent application is currently assigned to Stryker Leibinger GmbH & Co. KG. Invention is credited to Jose Luis MOCTEZUMA DE LA BARRERA, Amir Sarvestini.
Application Number | 20070175489 11/646994 |
Document ID | / |
Family ID | 31977775 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070175489 |
Kind Code |
A1 |
MOCTEZUMA DE LA BARRERA; Jose Luis
; et al. |
August 2, 2007 |
Method and system for calibrating a surgical tool and adapter
therefor
Abstract
A method for easily calibrating both the position of the tip of
a surgical tool and the orientation of that tool includes attaching
a tracking device capable of communication with the surgical
navigation system to the surgical tool using an adapter, where the
adapter has a known relation between the tracking device and the
axis of the surgical tool. The method then performs a calibration
process to calculate the position of the tip of the surgical tool
and the position of the tracking device and orientation data for
the surgical tool from the known relation between the tracking
device and the axis of the surgical tool and from the tool tip
position. Lastly, the method stores the position of the tool tip
for the surgical tool and the orientation data within memory of the
surgical navigation system so the position and the orientation of
the surgical tool can be tracked by the surgical navigation system.
The adapter has a body with an interior surface that defines an
opening through which a surgical tool can be inserted, the opening
having an axis. The adapter also has a docking structure for a
tracking device such that there is a known relation between the
tracking device and the axis of the opening and the axis of a tool
that is inserted in the opening.
Inventors: |
MOCTEZUMA DE LA BARRERA; Jose
Luis; (Freiburg, DE) ; Sarvestini; Amir;
(Freiburg, DE) |
Correspondence
Address: |
MCCRACKEN & FRANK LLP
200 W. ADAMS STREET
SUITE 2150
CHICAGO
IL
60606
US
|
Assignee: |
Stryker Leibinger GmbH & Co.
KG
|
Family ID: |
31977775 |
Appl. No.: |
11/646994 |
Filed: |
December 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10246599 |
Sep 18, 2002 |
7166114 |
|
|
11646994 |
Dec 28, 2006 |
|
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|
Current U.S.
Class: |
128/898 ;
606/1 |
Current CPC
Class: |
G16H 40/20 20180101;
A61B 2034/252 20160201; A61B 2034/207 20160201; A61B 2017/00477
20130101; A61B 2034/256 20160201; A61B 2034/2068 20160201; G06F
19/00 20130101; G16H 40/40 20180101; A61B 34/20 20160201; A61B
2034/2072 20160201; A61B 2034/2055 20160201; A61B 2090/3983
20160201; A61B 2017/00725 20130101 |
Class at
Publication: |
128/898 ;
606/001 |
International
Class: |
A61B 19/00 20060101
A61B019/00; A61B 17/00 20060101 A61B017/00 |
Claims
1-10. (canceled)
11. An adapter to attach a tracking device to a surgical tool
having an axis comprising: a body having an exterior surface, and
an interior surface; a docking structure for the tracking device
attached to the exterior surface; and the interior surface defining
an opening having an axis, the opening having a shape to engage the
surgical tool such that there is identity between the axis of the
opening and the axis of the surgical tool.
12. The adapter of claim 11 wherein the docking structure locks the
tracking device into a specified position with respect to the
body.
13. The adapter of claim 11 wherein the tracking device is an
optical tracking device.
14. The adapter of claim 13 wherein the optical tracking device
includes infrared LED's.
15. The adapter of claim 11 wherein the body slides onto the
surgical tool.
16. The adapter of claim 11 wherein the body fits into an
attachment device on the surgical tool.
17. The adapter of claim 11 wherein the body snaps into an
attachment device on the surgical tool.
18. The adapter of claim 11 wherein the adapter includes a
proximity detecting device to determine the presence of a surgical
tool.
19. The adapter of claim 11 wherein the adapter includes a
communication transceiver.
20. The adapter of claim 11 wherein there are two docking
structures attached to the exterior surface.
21.-62. (canceled)
Description
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/246,599, filed Sep. 18, 2002.
FIELD OF THE INVENTION
[0002] This invention generally relates to calibrating surgical
tools for use with a surgical navigation system. More particularly
this invention relates to the calibration of a combination of a
universal tracking device and the surgical tool so that the
position and orientation of the surgical tool can be determined by
the surgical navigation system.
BACKGROUND OF THE INVENTION
[0003] The use of image guided surgical navigation systems for
assisting surgeons in performing delicate surgery has become more
common. Typical surgical navigation systems utilize specially
developed tools that include built in tracking devices so that the
surgeon can see the position of the surgical tool overlaid on a
monitor that shows a preoperative image or an intraoperative image.
The preoperative images are typically prepared using well-known
preoperative scanning techniques, such as MRI or CT scans. The
intraoperative images can be prepared using flouroscope, low level
x-ray and similar devices. The tracking devices typically include
multiple optical emitters, such as LED's, that can be detected by
the surgical navigation system. From the position of the emitters,
the surgical navigation system can determine the position and/or
orientation of the surgical tool.
[0004] As used in this specification, the term position means the
coordinates of the tip of the surgical tool in three-dimensional
space, the x, y, z or Cartesian coordinates, relative to the
surgical navigation system. The term orientation means the pitch,
roll, and yaw of the surgical tool. When both the position and the
orientation of a surgical tool are defined, the absolute position
of that surgical tool is known to the surgical navigation
system.
[0005] In order for a surgeon to use a surgical tool without a
built in tracking device with a surgical navigation system, a
universal tracking device must be attached to the surgical tool.
The universal tracking device and the surgical tool combination
must be calibrated so that the surgical navigation system knows the
relation between tip of the surgical tool and the position of the
tracking device. Surgical tools with the attached universal
tracking device can be calibrated and then tracked. If the tracking
device and surgical tool have been calibrated relative to the
surgical navigation system so that only the position of the tip of
the surgical tool is known to the surgical navigation system, then
only the position of the tip but not the orientation of the
surgical tool can be tracked by the system. Because the exact path
the surgeon will take during a particular surgical procedure is
very important, it is preferable to know both the position and
orientation of the surgical tools used during that procedure so
that the surgical tools can be completely represented on the
monitor of typical surgical navigation systems.
[0006] In order to provide both position and orientation data for
the combination of the surgical tool and the attached universal
tracking device, both the position and orientation for each
surgical tool and tracking device combination must be calibrated.
Typical prior calibration devices have been described in U.S. Pat.
Nos. 5,987,960, 5,921,992 and 6,306,126. Each of these calibration
devices utilizes the principal of constraining the axis of the
surgical tool in a plane perpendicular to a base of the calibration
device. Because the position of the base of the calibration device
and the position of the axis of the surgical tool are known
relative to optical tracking elements contained on the calibration
device, the surgical navigation system can calculate the position
and the orientation for the particular surgical tool and the
tracking device combination. Thereafter, that surgical tool and
tracking device combination can be completely tracked by the
surgical navigation system.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to an improved method of
calibrating both the position and orientation of a surgical tool
for use with a surgical navigation system. This method includes the
steps of attaching a tracking device capable of communicating with
the surgical navigation system to the surgical tool using an
adapter, wherein the surgical tool has both a tool axis and a tool
tip and the adapter has a known relation between the tracking
device and the tool axis. The method further includes the step of
touching the tool tip to a calibration device capable of
communicating with the surgical navigation system and capable of
determining the position of the tool tip relative to the position
of the tracking device. The method further includes the step of
calculating the position of the tool tip and then calculating
orientation data for the surgical tool from the known relation
between the tracking device and the tool axis. Lastly, the method
includes the step of storing the position of the tool tip and the
orientation data for the surgical tool within memory of the
surgical navigation system so that when the surgical tool is used
with the surgical navigation system, the position and the
orientation of the surgical tool can be tracked by the surgical
navigation system.
[0008] A further method of the present invention for calibrating
the position and the orientation of the surgical tool for use with
the surgical navigation system comprises the following steps. The
first step is attaching a tracking device capable of communicating
with the surgical navigation system to the surgical tool using an
adapter wherein the surgical tool has a tool axis and a tool tip
and the adapter has a known relation between the tracking device
and the tool axis. The second step in the method is touching the
tool tip to a calibration device capable of communicating with the
surgical navigation system and capable of determining a position of
the tip of the surgical tool relative to a position of the tracking
device. The method further includes the step of calculating the
position of tool tip and the step of storing the position of the
tool tip within memory of the surgical navigation system. Lastly,
the method includes the step of determining orientation data for
the surgical tool from the position of the tool tip and from a
database of stored relations of the tracking device to the tool
axis and from the position of the tool tip such that the position
of the tool tip intersects an axis of the surgical tool from the
database so that when the surgical tool is used with the surgical
navigation system, the position and orientation of the surgical
tool can be tracked by the surgical navigation system.
[0009] The present invention also is directed to an adapter to
attach a tracking device to a surgical tool having axis, which
comprises a body having an exterior surface, and an interior
surface. The adapter also includes a docking structure for the
tracking device attached to the exterior surface. Lastly, the
adapter includes the interior surface that defines an opening
extending through the body, the opening having an axis and the
opening having a shape to engage the surgical tool such that there
is identity between the axis of the opening and the tool axis.
[0010] The present invention further includes a system for the
calibration of a surgical tool for use with a surgical navigation
system. The system comprises a memory unit, an adapter that can be
attached to a surgical tool having a tool tip and a tool axis, and
a tracking device attached to the adapter, the tracking device
capable of being tracked by the surgical navigation system, wherein
the adapter has a known relation between the tracking device and
the tool axis. The system further includes a calibration device
capable of determining the position of the tool tip relative to the
position of the tracking device and capable of communicating with
the surgical navigation system. The system also includes a first
circuit operative to calculate the position of the tool tip
relative to a position of the tracking device and an orientation of
the surgical tool from the known relation between the tracking
device and the tool axis and from the position of the tool tip, and
a second circuit operative to store the position of the tool tip
and the orientation of the tool in the memory unit.
[0011] A further system of the present invention for calibrating a
position and an orientation of a surgical tool for use with a
surgical navigation system comprises means for attaching a tracking
device capable of communication with the surgical navigation system
to the surgical tool using an adapter, the surgical tool having a
tool axis and a tool tip, and the adapter having a known relation
between the tracking device and the tool axis. The system also
includes means for calculating a position of the tool tip by
touching the tool tip to a calibration device capable of
communication with the surgical navigation system and capable of
determining the position of the tool tip relative to a position of
the tracking device and means for calculating orientation data for
the surgical tool from the known relation between the tracking
device and the tool axis and from the position of the tool tip. In
addition, the system includes means for storing the position of the
tool tip for the surgical tool and the orientation data for the
surgical tool within memory of the surgical navigation system so
that when the surgical tool is used with the surgical navigation
system, the position and the orientation of the surgical tool can
be tracked by the surgical navigation system.
[0012] A still further system of the present invention for
calibrating a surgical tool for use with a surgical navigation
system comprises a memory unit and means for attaching an adapter
to a surgical tool having a tool tip and a tool axis. The system
also includes means for tracking the surgical tool attached to the
adapter, the tracking means capable of being tracked by the
surgical navigation system, wherein the adapter has a known
relation between the tracking device and the tool axis and means
for calibrating capable of determining a position of the tool tip
relative to the position of the tracking means and capable of
communicating with the surgical navigation system. The system
further includes means for calculating the position of the tool
tip; and an orientation of the surgical tool from the known
relation between the tracking device and the tool axis and from the
position of the tool tip, and means for storing the position of the
tool tip and the orientation of the surgical tool in the memory
unit.
[0013] Another system of the present invention for calibrating a
position and an orientation of a surgical tool for use with a
surgical navigation system comprises means for attaching a tracking
device capable of communication with the surgical navigation system
to the surgical tool using an adapter, the surgical tool having a
tool axis and a tool tip, and the adapter having a known relation
between the tracking device and the tool axis. The system also
includes means for calculating a position of the tool tip by
touching the tool tip to a calibration device capable of
communicating with the surgical navigation system and capable of
determining the position of the tool tip relative to a position of
the tracking device, and means for storing the position of tool tip
within memory of the surgical navigation system. In addition the
system has means for determining orientation data for the surgical
tool from the position of the tool tip and from a database of
stored relations of the tracking device to the tool axis and from
the position of the tool tip, such that the position of the tool
tip intersects an axis of the surgical tool from the database, so
that when the surgical tool is used with the surgical navigation
system the position and the orientation of the surgical tool can be
tracked by the surgical navigation system.
[0014] Other aspects and advantages of the present invention will
become apparent upon consideration of the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic view of the surgical navigation
system;
[0016] FIG. 1a is a block diagram of the surgical navigation system
of FIG. 1;
[0017] FIG. 2 is an isometric view of the adapter according to the
present invention;
[0018] FIG. 3 is a side elevational view of the adapter of FIG.
2;
[0019] FIG. 4 is an end elevational view of the adapter of FIG.
2;
[0020] FIG. 5 is an end elevational view of the adapter of FIG. 2
from the end opposite FIG. 4;
[0021] FIG. 6 is a sectional view of the adapter of FIG. 2 taken
generally along the line 6-6;
[0022] FIG. 7 is an isometric view of the surgical tool with the
adapter in place;
[0023] FIG. 8 is an isometric view of an alternative embodiment of
the adapter of the present invention;
[0024] FIG. 9 is a side view of the adapter of FIG. 8;
[0025] FIG. 10 is an end view of the adapter of FIG. 8;
[0026] FIG. 11 is an end view of the adapter of FIG. 8 from the end
opposite FIG. 10;
[0027] FIG. 12 is a sectional view the adapter of FIG. 8 taken
generally along the lines 11-11;
[0028] FIG. 13 is an isometric view of a surgical tool to be used
with the adapter of FIG. 8;
[0029] FIG. 14 is an isometric view of a universal tracking
device;
[0030] FIG. 15 is exploded view of the adapter of FIG. 8, the
surgical tool of FIG. 14, and the universal tracking device of FIG.
13;
[0031] FIG. 16 is an assembled view of the adapter of FIG. 8, the
surgical tool of FIG. 14, and the universal tracking device of FIG.
13;
[0032] FIG. 17 is a view of the calibration device showing the
surgical tool of FIG. 14 with the adapter of FIG. 8 and the
universal tracking device of FIG. 13 touching the calibration
point;
[0033] FIG. 18 is a block diagram of a computer program embodying
the method of the present invention;
[0034] FIGS. 18a, 18b, 18c, 18d and 18e are representative screen
shots of various messages boxes as depicted in FIG. 18;
[0035] FIG. 19 is a block diagram of a computer program of an
alternative method of the present invention; and
[0036] FIG. 20 is an isometric view of a further embodiment of the
adapter similar to that shown in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] FIGS. 1 and 1a are a schematic view and block diagram of a
surgical navigation system 50 adapted to track surgical tool 52
having a universal tracking device 54 associated therewith using an
adapter 56. The surgical navigation system 50 includes a computer
58, which can be any type of high-speed personal computer having a
CPU 58a, a memory unit 58b, and a storage unit 58c, such as a
laptop computer, as shown, or a desktop computer (not shown). If
the desktop computer is used, it can be housed inside a cart 62.
Mounted on the cart 62 is a monitor 60, which is attached to a
video output of the computer 58. Also associated with the computer
58 are a mouse 64 or another suitable input pointing device and a
keyboard 66. The surgical navigation system 50 includes a camera 68
which is comprised of three separate CCD cameras 70, 72 and 74,
which cameras are adapted to detect infrared signals (IR) generated
by the universal tracking device 54. The camera 68 is mounted on
cart 60 by a camera arm 76. While the camera 68 is shown mounted in
association with the cart 62 in FIG. 1, it is not necessary that
the camera actually be physically mounted on or attached to cart
62. The camera 68 can be mounted in any stationary position such
that the camera 68 has a good line of sight to the operating field
in the operating room. For instance, the camera 68 can be mounted
on a wall of the operating room (not shown) or can be mounted on
the operating room light (not shown). Camera arm 76 also can
include cable 86 from the camera 68 to a localizer 88 which is
located within cart 62. The localizer 88 cooperates with the camera
68 to identify the locations of the LED's 84 on the universal
tracking device 54 and any other tracking devices that may be
within the field of view of the camera 68. The CCD cameras 70, 72,
and 74 contain their own calibration information and transmit the
position data from the LED's 84 to the localizer 88. The localizer
88 then converts the raw position data into position and
orientation data using techniques that are to those of skill in the
art. The localizer 88 communicates the position and orientation
data to the computer 58 through cable 90. The camera 68 also
includes two transceivers 92 and 94 capable of communicating with
the universal tracking device 54 using techniques that are
well-known to those of skill in the art. The transceivers 92 and 94
are directly connected to computer 58 through a separate circuit in
cable 86. Also shown is a reference tracking device 78 attached to
operating room table 80 by a tracker mount 82. While it is
preferred that the reference tracking device 78 is stationary, the
reference tracking device 78 could be mounted to a patient (not
shown) or could be a second hand held tracking device. Both the
reference tracking device 78 and the universal tracking device 54
have multiple LED's 84 that emit light in the infrared region that
can be detected by CCD cameras 70, 72 and 74. A more detailed
description of surgical navigation system 50 is contained in U.S.
patent application Ser. No. 09/764,609 filed Oct. 21, 2001, the
disclosure of which is hereby incorporated by reference.
[0038] With reference to FIGS. 2-7, the adapter 56 includes a body
102 having a docking pin bridge 104. The body 102 has an exterior
surface 106 and an interior surface 108. An opening 112 is defined
by the interior surface 108 and passes through the body 102. The
opening 112 has an axis 110, as shown in FIG. 2. The axis 110 must
have a known relation to the interior surface 108 of the adapter
56.
[0039] Multiple docking pins 114 are mounted on docking pin bridge
104. In the embodiment as shown in FIGS. 2-7, four docking pins 114
are shown. The multiple docking pins 114 are provided to enable a
surgeon to mount the universal tracking device 54 on the most
appropriate docking pin 114 so that during the surgical procedure
to be performed the LED's 84 in the universal tracking device 54
can readily maintain a line of sight to the camera 68. While four
docking pins 114 are shown in the embodiment of FIGS. 2-7, any
suitable number of docking pins can be included. The docking pins
114 include a base 115, which is firmly secured to docking bridge
104 in such a manner that the docking pin 114 does not move once it
has been secured to docking bridge 104. The docking pin 114 also
includes two pins 116 and an undercut 118, which interact with the
docking surface of the universal tracking device 54 as will be
discussed in more detail hereafter to hold the universal tracking
device 54 firmly to the adapter 56.
[0040] The opening 112 passes completely through the body 102 and
is formed such that when a surgical tool 52 is placed through the
opening 112, a tool axis 120 of the surgical tool 52 will be
identical to the axis 110 of opening 112. This identity of the axis
110 and the tool axis 120 is an important aspect of the adapter 56.
It enables the adapter 56 to be used with the reference tracking
device 78 to calibrate not only the position of a tool tip 126 of
surgical tool 52 but also calibrate the tool axis 120 such that
surgical navigation system 50 can track both the position and the
orientation of the surgical tool 52. The opening 112 and its axis
110 can be off set from the center of the body 102 if the surgical
tool 52 is to be nonrotably held by the adapter 56.
[0041] Once the adapter 56 is placed on the surgical tool 52, it is
important that the position of the adapter 56 relative to the tool
tip 126 and the tool axis 120 remain undisturbed. While it is
possible that the adapter 56 may be configured to rotate in place
about the tool axis 120, so long as the distance from the tool tip
126 to the location of the universal tracking device 54 remains
unchanged and so as long as the relation between the universal
tracking device 54 and the tool axis 120 of the tool remains
unchained, the position and orientation of the surgical tool 52 can
be calibrated and tracked by the surgical navigation system 50.
[0042] In order to maintain the adapter 56 in a fixed location
relative to the tool tip 126, spring-loaded balls 122 are provided
within the interior of opening 112 and the interior surface 108 of
body 102. These balls 122 are biased outwardly by springs 124 and
cooperate to firmly engage the surgical tool 52 so that the
relationship between the adapter 56 and the surgical tool 52 is
maintained. For instance, the surgical tool 52 may have a small
channel (not shown) within which balls 122 rest thereby holding the
adapter 56 in a fixed relation with regard to the tool tip 126.
Other means of firmly attaching the adapter 56 to the surgical tool
52 can also be used.
[0043] As shown in FIGS. 8-13, a second embodiment of the adapter
56 is shown. In describing FIGS. 8-13 similar structure will be
described using the same reference number as above. An adapter 150
includes the docking pin bridge 104 and has the exterior surface
106 and the interior surface 108. As shown in FIG. 8, an axis 168
passes through an opening 152 defined by the interior surface 108.
The opening 152 in the adapter 150 is larger than the opening 112
of the adapter 56. The reason for this larger opening is to
interact with an attachment device 154 mounted on a surgical tool
156. On the exterior surface 106 of the adapter 150 are a series of
detents 158. Detents 158 interact with a series of balls 160 held
within an interior surface 162 of the attachment device 154. These
balls 160 are held in place by a locking ring 164 that encircles
the exterior of the attachment device 154. The attachment device
154 also includes a smooth protrusion 166 that is shaped so that it
closely interfits with the opening 152 of the adapter 150. The
shape of the smooth protrusion 166 is such that the axis 168 of the
opening 152 is in identity with a tool axis 170 of the surgical
tool 156. In addition, a series of grooves 172 are shown on the
exterior surface 106 of the adapter 150. These grooves are arranged
around the end of the adapter 150 opposite the docking pin bridge
104. These grooves 172 interact with one or more pins 174 in a back
surface 176 of the attachment device 154. The grooves 172 and the
pins 174 keep the adapter 150 from rotating about the axis 168.
Either or both of grooves 172 or pins 174 can be omitted if it is
desired that the adapter 156 be able to rotate freely about the
axis 168.
[0044] As shown in FIGS. 6 and 12, the adapters 56 and 150 of the
present invention be made from any suitable material that is
dimensionally stable and capable of being sterilized at least one
time. Though it may be desirable that the adapter be capable of
being repeatedly sterilized, it is also possible that the adapters
of the present invention are designed as disposable single use
items, which are sterilized upon manufacture, maintained in a
sterile condition until use and then discarded. As shown in FIG. 6,
suitable plastics, which are dimensionally stable and surgically
acceptable, such as polyetheretherketone (PEEK), carbon fiber
reinforced PEEK, polysulfone, polycarbonate, nylon and mixtures
thereof, can be used. In addition, as shown in FIG. 12, suitable
metals that are acceptable for use in surgery such as surgical
stainless steel, titanium, tungsten carbide and other similar
surgically suitable metals can be used.
[0045] Turning now to FIG. 14, the universal tracking device 54 is
shown in more detail. The universal tracking device 54 as shown in
FIG. 14 includes five LED's 84, which are arranged such that no
three LED's lie in a single line. This arrangement enables the
surgical navigation system 50 to determine both the position and
the orientation of the universal tracking device 54. As stated
previously, these LED's 84 typically emit light in the infrared
region as is well known to those of ordinary skill in the art. The
universal tracking device 54 has a button 98. This button 98
activates the LED's 84 so that the camera 68 of the surgical
navigation system 50 can locate the universal tracking device. The
universal tracking device 54 also includes a status light 190 which
can be programmed to operate in a variety of ways. For instance,
the status light 190 can be programmed so it is illuminated for a
short period of time after a power source such as a battery 194 is
inserted into a suitable battery holder in the universal tracking
device 54. The universal tracking device 54 also includes a zero
tolerance adapter interface 195, which includes an opening 196
through which one of the docking pins 114 can be inserted. The
structure of the opening 196 and the docking pins 114 are such that
when the docking pin 114 is inserted through the opening 196, an
internal lock (not shown) snaps around undercut 118. The internal
lock can be released by pressing a button 198 to remove the
universal tracking device 54 from the docking pin 114. The
importance of the zero tolerance nature of the adapter interface is
that once that the universal tracking device 54 is placed upon the
docking pin 114, the relative position of the universal tracking
device 54 and the docking pin 114 must not be disturbed. Once the
composite universal tracking device 54, adapter 150 and surgical
tool 156 is calibrated, the surgical tool 156 can be tracked by the
surgical navigation system 50. However, if the relation among these
components is disturbed, the composite unit must be
recalibrated.
[0046] In addition, the universal tracking device 54 also includes
a calibration point 200. The calibration point 200 is in a known
relation to LED's 84 and has a center point that is easily
identified so that the universal tracking device 54 can be used
also as a reference tracking device 78, as shown in FIG. 1. In
addition, the universal tracking device 54 includes a communication
transceiver 202 that enables the universal tracking device to
communicate directly with the surgical navigation system 50 through
the transceivers 92 and 94.
[0047] FIG. 15 shows an exploded view of the universal tracking
device 54, the adapter 150, and the surgical tool 156. In use, the
adapter 150 is slid along the length of the surgical tool 156 until
the adapter 150 firmly engages attachment device 154, which is
firmly attached to the surgical tool 156. Typically the attachment
device 154 is formed along with the surgical tool 156 during the
manufacture but it is also possible to retrofit the attachment
device 154 onto the surgical tool 156 by means of a suitable
attachment means (not shown). In FIG. 16, a view of the surgical
tool 156, the adapter 150, and the universal tracking device 54 in
an assembled configuration is shown. As noted previously, the
surgical tool 156 and the attached universal tracking device 54
must be calibrated before it can be used with the surgical
navigation system 50.
[0048] As shown in FIG. 17, the tool tip 126 is placed against the
calibration point 200 of the reference tracking device 78. Both the
location of the calibration point 200 on the reference tracker
device 78 and the position of universal tracking device 54 are
known to the surgical navigation system 50. Because of this known
relation, the surgical navigation system 50 can determine the
location of tool tip 126 relative to the universal tracking device
54 as the tool tip 126 is held against the calibration point 200.
The surgical navigation system 50 then stores the tool tip location
and the relation of the tool tip location to the universal tracking
device 54 within the memory 58b of the computer 58. In addition,
the surgical navigation system 50 is able to calibrate the
orientation of the surgical tool 156 because the adapter 150 is
used to attach the universal tracker device 54 to the surgical tool
156. The adapter 150 has a known and previously defined
relationship among the various docking pins 114 to the axis 168 of
the opening 152 and to the tool axis 170. Also, the relationship
between each docking pin 114 and the universal tracking device 54
is also known and previously defined. These relationships are
stored within a database maintained in the memory 586 of the
computer 58 for each adapter that can be used with the surgical
navigation system 50.
[0049] FIG. 18 is a block diagram of a computer program embodying
the method of the present invention. The program begins at a block
300 which determines if a calibration device, such as the reference
tracking device 78, is active. If the device is not active, the
program branches to a block 301, which displays a message, as shown
in FIG. 18a, that the calibration device should be switched on. The
program returns to the block 300 and waits until the surgical
navigation system 50 receives a signal that the calibration device
has been turned on. Once the calibration device has been activated,
the program then branches to a block 302, which displays a message,
as shown in FIG. 18b, instructing the user first to touch the point
of the tool, such as tool tip 126, to the calibration point on the
calibration device, such as calibration point 200, and second to
press the button on the tracking device, such as the button 98.
When the button 98 is activated, the LED's 84 on the universal
tracking device 54 activate and are detected by the camera 68. The
portion data for the LED's 84 is sent to the localizer 88 which
transmits the position and orientation of universal tracking device
54 to computer 68. This is data stored in memory 58b and is shown
as a data block 303. In a similar manner, the surgical navigation
system 50 determines the position and orientation of the
calibration device, such as reference tracking device 78. This data
is also stored in memory 58b and is shown as a data block 304. The
program then proceeds to a calculation block 305. In the block 305,
the program calculates the tool tip position from the stored data
position of the tracking device from the data block 303 and the
stored position of the calibration device in the data block 304.
The calculation of the tool tip position, is done in a conventional
fashion using algorithms that are well known and recognized by
those of skill in the art.
[0050] The tool tip position from the calculation block 305 is then
stored and the stored tool tip position is passed to a calculation
block 306 that calculates the orientation data for the surgical
tool 156. In addition to the tool tip position from the block 305,
surgical navigation system 50 has the database 96 of possible axes
for the opening 152 relative to location of the universal tracking
device 54 stored in memory 58b in the database 96. The database 96
is shown as a data block 306 and contains data previously stored in
memory 58b relative to the relative position of the universal
tracking device 54 relative to the possible axes of the opening for
various adapters, such as axis 110 or axis 168. Since the adapter
56 and the adapter 150 can have a number of different docking pins
114, each of these docking pins is in a different position and
orientation relative to the axis 110 and axis 168, respectively.
The relative position of the universal tracking device 54 to either
the axis 110 or the axis 168 for each docking pin 114 can be
calculated by methods well known in the art. The result of this
calculation for the location each docking pin 114 for each possible
adapter that can be used with the surgical navigation system 50 is
stored in the database 96 which has been previously loaded into in
the memory of computer 58b on initialization of the program.
[0051] As there can be number of different adapter configurations,
the distance from the universal tracking device 54 to the axis of
each particular adapter will vary. Each type of adapter can be
encoded with a specific identifier that can be entered into the
surgical navigation system 50. This can be done manually using the
keyboard 66 or the mouse 64 to indicate which adapter is being used
or automatically using a smart adapter 500 as shown in FIG. 20. The
adapter 500 has a communication transceiver 502 which is capable of
transmitting information stored in the adapter 500, such as a
particular model number and/or style number, to the surgical
navigation system 50 through communication transceivers 92 and
94.
[0052] Once the surgical navigation system 50 knows the identity of
the particular adapter, the database 96 is queried for the
potential axis for the particular adapter being used, such as the
adapter 150, and the subset of the data is placed in memory as
indicated by the data block 306 along with the tool tip position
from the block 305. The subset of data stored in the data block 306
from database 96 is then used to calculate the orientation data.
The program proceeds to a block 307, which calculates the
orientation data by comparing the tool tip position with the data
subset that has been taken from database 96 stored in the data
block 306 for that particular adapter. If the tool tip position is
located along any of the potential axes from the data block 306 and
if the deviation of the tool tip position from the chosen potential
axis is within acceptable limits, then the program branches, as
shown in a block 308, to the validation process. If the position of
the tool tip is not on one of the axes within acceptable limits,
the program branches to block 309 that displays an error message as
shown in FIG. 18d. Control then loops back to the block 302 to
repeat the calibration process.
[0053] At the beginning of the validation process, a block 310
displays a message as shown in FIG. 18c. The message instructs the
user to touch the tool tip to the calibration point 200 of the
calibration device, and then to press the button 98. Once the
button 98 is pressed, the surgical navigation system 50 determines
the position of the universal tracking device 54 as described above
and stores the position in a data block 312. Also, the position of
the calibration device is determined in the same manner as above
and a data block 311 stores the position of the calibration device.
A block 313 then compares the position stored in the data block 311
with the stored tool tip position from the block 305. If the
comparison by the block 313 is within acceptable error limits, a
block 314 determines whether the calibration has been validated and
the axis data and the tool tip position data are then written into
memory 58b as indicated by block 318. If the validation process
does not succeed, i.e., if the comparison is greater than the
acceptable error, then the program branches and a block 315
displays the message as shown in FIG. 18e that instructs the user
to repeat the calibration step. At any time during either the
calibration or validation step, the user has the option to cancel
the entire process and either begin calibration again or return to
another task.
[0054] FIG. 19 shows a block diagram for an alternative method of
the present invention. The program begins at a block 400 that
determes if a calibration device is active. If the calibration
device is not active, a block 401 displays a message and the
program waits until a calibration device is activated. The message
displayed in the block 401 is similar to that shown in FIG. 18a.
After a calibration device is activated, a block 402 displays a
message similar to that shown in FIG. 18b. Once the user touches
the tool tip 126 to the calibration point 200 on the reference
tracking device 78 and presses the tracker button 98 on the
universal tracking device 54, a block 403 calculates the tool tip
position using the data generated from the position of the
universal tracking device 54 stored in a data block 404, and the
data on the position of the calibration device stored in a data
block 405. The tool tip position is calculated by the block 403 in
a manner similar to that described in reference to FIG. 18. Once
the tool tip position has been determined and stored, a block 406
determines whether or not the calibration step has been
successfully completed. If the calibration step did not succeed,
for instance, if one of the tracking devices was not visible to the
surgical navigation system 50, a block 416 displays an error
message indicating the nature of the error.
[0055] If the calibration is concluded, the block 406 stores the
tool tip position in memory, the program precedes to a block 407
that displays the validation message that is similar to that shown
in FIG. 18c. The message instructs user to touch the tool tip 126
to the calibration point 200 on reference tracker device 78 and
then press the activation button 98 on the universal tracking
device 54. As the tracking device is activated, a block 408
determines and stores the tracking device position and a block 409
determines and stores the calibration position in a manner similar
to that described above. A block 410 then compares the validation
tool tip location with the stored tool tip position. If a block 411
determines that the variation between the tool tip position stored
in the block 403 and the validation value determined by the block
410 is greater than an acceptable limit, the validation is not
successful and branches, as indicated in a decision, a block 421
displays an error message. This error message will be similar to
that shown in FIG. 18e. On the other hand, if the comparison in
block 410 is within acceptable error limits then the block 411
sends control to the axis calibration.
[0056] A block 412 determines axis calibration by taking the stored
validated tool tip position from the block 410 and determining
whether or not this tool tip position lies on any of the available
axes stored in a block 413 from the axis database. The axis
database is similar to that described relative to FIG. 18. The
block 412 compares the validated tool tip position with the
coordinates of any of the axes lines available to the system using
the appropriate adapter. If the tool tip position does lie on one
of the appropriate axes, that axis is chosen and a block 415
branches to a block 414 that writes the chosen axis and the tool
tip position data to memory 58b to provide a fully calibrated tool.
On the other hand, if the tool tip position does not lie on one of
the axes in the database within acceptable limits, the block 414
branches to a block 417 that writes only the tool tip position data
to the memory 58b, to create a point calibrated tool, i.e., a tool
that has only its tip position calibrated but the tool orientation
is not calibrated. After the appropriate data is written to memory,
the calibration task is finished and then the program exits and
proceeds to other tasks.
[0057] Turning now to FIG. 20, a third embodiment of the adapter of
the present invention is shown. In this embodiment, the adapter
500, which is similar to the adapter 150, is provided. This adapter
differs from the adapter 150 in that it has two additional
features. The first additional feature is the communication
transceiver 502 which enables the adapter 500 to communicate
information to the surgical navigation system 50. This information
may include the identity and type of the adapter so that the
appropriate data from the tool axis database can be chosen without
user intervention. Also, a switch 504 is shown on the interior
surface 108 of the adapter 500. This switch 504 will be depressed
or activated when the surgical tool 156 is inserted into the
opening 152 of adapter 500. Any suitable switch can be used as the
switch 504. For instance, the switch 504 could be one which when
depressed sends a signal through to the communication transceiver
502 to the surgical navigation system 50 indicating that one tool
156 has been inserted into adapter 500. Similarly, as one tool is
removed from opening 152 and a new device is placed into the
opening 152 of adapter 500, the switch is first opened as the tool
is removed and depressed as the new tool is inserted. This in turn
sends a signal through the communication transceiver 502 to the
surgical navigation system 50 indicating at a minimum that the
state of the adapter has changed and the tool needs to be
recalibrated. This may be important since the adapter could be used
for a wide variety of tools during a surgical procedure, each of
which would have a different length so that the distance from the
universal tracking device 54 to the tool tip be different. The
system then will prompt the user to recalibrate the new combination
of the universal tracking device 54, the adapter 500 and the
surgical tool 156 so that the correct data will be used and
displayed on the monitor 60. Similarly as a tool is removed, the
switch 504 will open and send a signal to the surgical navigation
system 50 informing the system that there is no tool associated
with that adapter and its associated universal tracking device.
This will make that particular tracking device, surgical tool and
adapter combination invalid for use with the system until
calibration is performed.
INDUSTRIAL APPLICABILITY
[0058] The present invention is useful to quickly and easily
calibrate both the position and orientation of a particular
surgical tool without the need for complicated calibration devices
that must be separately sterilized to be used within a surgical
environment.
[0059] Numerous modifications to the present invention will be
apparent to those skilled in the art in view of the foregoing
description. Accordingly, this description is to be construed as
illustrative only and is presented for the purpose of enabling
those skilled in the art to make and use the invention and to teach
the best mode of carrying out same. The exclusive rights to all
modifications which come within the scope of the appended claims
are reserved.
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