Note: Descriptions are shown in the official language in which they were submitted.
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SOFT BODY AUTOMATIC REGISTRATION AND
SURGICAL LOCATION MONITORING SYSTEM AND METHOD WITH SKIN
APPLIED FIDUCIAL REFERENCE
TECHNICAL FIELD
[0001] The invention relates to location monitoring hardware and software
systems. More
specifically, the field of the invention is that of surgical equipment and
software for
monitoring surgical conditions.
BACKGROUND ART
[0002] Visual and other sensory systems are known, with such systems being
capable of both
observing and monitoring surgical procedures. With such observation and
monitoring
systems, computer aided surgeries are now possible, and in fact are being
routinely
performed. In such procedures, the computer software interacts with both
clinical images of
the patient and observed surgical images from the current surgical procedure
to provide
guidance to the physician in conducting the surgery. For example, in one known
system a
carrier assembly bears at least one fiducial marker onto an attachment element
in a precisely
repeatable position with respect to a patient's jaw bone, employing the
carrier assembly for
providing registration between the fiducial marker and the patient's jaw bone
and implanting
the tooth implant by employing a tracking system which uses the registration
to guide a
drilling assembly. With this relatively new computer implemented technology,
further
improvements may further advance the effectiveness of surgical procedures.
SUMMARY OF THE INVENTION
[0003] Embodiments of the present invention involves a surgical monitoring
system
comprising a fiducial reference comprising radio-opaque elements, the fiducial
reference
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adherable to a location on skin proximate a surgical site; a tracker arranged
for obtaining
image information about the surgical site; and a controller having access to
pre-existing scan
data of the surgical site with the fiducial reference adhered to the skin, the
controller in
communication with the tracker and comprising a processor with memory and a
software
program having a series of instructions that when executed by the processor
determines the
position and orientation of the fiducial reference based on the image
information and the scan
data.
[0004] The radio opaque elements may comprise a plurality of pattern segments,
each
segment configured for having a segmental three-dimensional location and
orientation
determinable based on the image information and the scan data. The plurality
of pattern
segments may be borne on a surgical incise film configured for application to
the skin. The
plurality of pattern segments may comprise at least one of radio-opaque ink
and radio-opaque
paint.
[0005] The plurality of pattern segments may have an adhesive property and is
configured to
be adhered directly to the skin.
[0006] The plurality of pattern segments may comprise a transfer film and the
plurality of
pattern segments is configured to be transferable from the transfer film to
the skin. The
plurality of pattern segments may comprise one of a radio-opaque ink pattern
and a radio-
opaque paint pattern applied directly to the skin.
[0007] Each segment may be configured in at least one of marked and shaped to
allow the
segment to be uniquely identified from the scan data and from the image
information. At
least one of the plurality of pattern segments may have a unique
differentiable shape that
allows unique identification by the controller from at least one of the scan
data and the image
information.
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[0008] The controller may be configured for determining the locations and
orientations of at
least a selection of the pattern segments based on the image information and
the scan data.
The controller may be configured to calculate the locations and orientations
of anatomical
features in the proximity of the plurality of pattern segments.
[0009] The surgical monitoring system may further comprise tracking markers
attached to at
least a selection of the pattern segments, the tracking markers having at
least one of
identifying marks and orientation marks that allow their three-dimensional
orientations to be
determined by the controller from the image information. The surgical
monitoring system
may yet further comprise at least one tracking marker attached to at least one
implement
proximate the surgery site, wherein the controller is configured for
determining a location
and an orientation of the at least one implement based on the image
information and
information about the at least one tracking marker.
[00010] In another embodiment the fiducial reference may comprise a
plurality of non-
unique elements configured in a spatially arbitrary arrangement. The plurality
of non-unique
elements may comprise one of a plurality of radio-opaque ink marks and a
plurality of radio-
opaque paint marks, which marks may be dots.
[00011] Another aspect of the invention involves a method for tracking
in real time
changes in a surgical site of a patient, the method comprising the steps of:
removably
adhering a fiducial reference to a fiducial location on the patient body
proximate the surgical
site, the fiducial reference comprising a plurality of pattern segments
individually locatable
based on scan data; performing a scan with the fiducial reference attached to
the fiducial
location to obtain the scan data; determining the three-dimensional locations
and orientations
of at least a selection of the pattern segments based on the scan data;
obtaining real time
image information of the surgical site; determining in real time the three-
dimensional
locations and orientations of the at least a selection of the pattern segments
from the image
information; and deriving in real time the spatial distortion of the surgical
site by comparing
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in real time the three-dimensional locations and orientations of the at least
a selection of the
pattern segments as determined from the image information with the three-
dimensional
locations and orientations of the at least a selection of the pattern segments
as determined
from the scan data.
[00012] Yet another aspect of the invention involves a method for relating
in real time
a three-dimensional location and orientation of a surgical site to a location
and orientation of
the surgical site in a scan of the surgical site, the method comprising the
steps of: applying a
fiducial reference in the form of a radio-opaque marker on skin proximate the
surgical site;
performing the scan to obtain scan data; determining three-dimensional
location and
orientation of the fiducial reference from the scan data; obtaining real time
image
information of the surgical site; determining in real time three-dimensional
location and
orientation information of the fiducial reference from the image information;
and deriving a
spatial transformation matrix for expressing in real time the three-
dimensional location and
orientation of the fiducial reference as determined from the image information
in terms of the
three-dimensional location and orientation of the fiducial reference as
determined from the
scan data. The fiducial reference may include a plurality of pattern segments
individually
locatable based on the scan data; the step of determining the three-
dimensional location and
orientation of the fiducial reference from the scan data comprises determining
the three-
dimensional location and orientation of at least one of the plurality of
pattern segments from
the scan data; and the step of determining in real time the three-dimensional
location and
orientation of the fiducial reference from the image information comprises
determining the
three-dimensional location and orientation of the at least one of the
plurality of pattern
segments from the image information.
[00013] The step of applying the fiducial reference to the skin
proximate the surgical
site may comprise applying a surgical incise film bearing the fiducial
reference. The step of
applying the fiducial reference on the skin proximate the surgical site may
comprise:
applying a surgical incise film to the skin over the surgical site; and
applying the fiducial
reference pattern to the surgical incise film proximate the surgical site
before surgery.
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[00014] The step of applying a fiducial reference on the skin
proximate the surgical
site may comprise applying one of radio-opaque ink and radio-opaque paint
directly to the
skin proximate the surgical site. In a further embodiment the step of applying
the fiducial
reference may comprise transferring the plurality of pattern segments from a
transfer tape. In
yet a further embodiment the step of applying the plurality of pattern
segments can comprise
applying one of radio-opaque ink and radio-opaque paint directly to the skin
using one of a
mask and a stencil bearing the plurality of pattern segments.
[00015] A further aspect of the invention involves a method for
tracking in real time
changes in a surgical site, the method comprising the steps of: applying a
multi-element
fiducial reference to skin proximate the surgical site, the multi-element
fiducial reference
comprising a plurality of pattern segments individually locatable based on
scan data;
performing a scan of the surgical site to obtain the scan data; determining
three-dimensional
locations and orientations of at least a selection of the pattern segments
based on the scan
data; obtaining real time image information of the surgical site; determining
in real time
three-dimensional locations and orientations of the at least one of the
pattern segments from
the image information; and deriving in real time the spatial distortion of the
surgical site by
comparing in real time the three-dimensional locations and orientations of the
at least one of
the pattern segments as determined from the image information with the three-
dimensional
locations and orientations of the at least one of the pattern segments as
determined from the
scan data.
[00016] The step of applying the fiducial reference on the skin
proximate the surgical
site may comprise applying a surgical incise film bearing the plurality of
pattern segments. In
other embodiments the step of applying the fiducial reference on the skin
proximate the
surgical site may comprise: applying a surgical incise film to the skin over
the surgical site;
and transferring the plurality of pattern segments to the surgical incise film
proximate the
surgical site before surgery.
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[00017] In yet further embodiments the step of applying the fiducial
reference on the
skin proximate the surgical site may comprise applying the plurality of
pattern segments in
the form of one of radio-opaque ink and radio-opaque paint directly to the
skin proximate the
surgical site. The step of applying the fiducial reference may comprise
transferring the
plurality of pattern segments from a transfer tape.In an alternative
embodiment the step of
applying the plurality of pattern segments may comprise applying one of radio-
opaque ink
and radio-opaque paint directly to the skin using one of a mask and a stencil
bearing the
plurality of pattern segments.
[00018] Another aspect of the invention involves a method for real
time monitoring
three-dimensional location and orientation of an object in relation to a
surgical site of a
patient, the method comprising: applying a fiducial reference on the skin
proximate the
surgical site; performing a scan of the surgical site to obtain scan data;
determining three-
dimensional location and orientation of the fiducial reference from the scan
data; obtaining
real time image information of the surgical site; determining in real time
three-dimensional
location and orientation of the fiducial reference from the image information;
deriving a
spatial transformation matrix for expressing in real time the three-
dimensional location and
orientation of the fiducial reference as determined from the image information
in terms of the
three-dimensional location and orientation of the fiducial reference as
determined from the
scan data; determining in real time three-dimensional location and orientation
of the object
from the image information; and relating the three-dimensional location and
orientation of
the object to the three-dimensional location and orientation of the fiducial
reference as
determined from the image information. The step of determining in real time
the three-
dimensional location and orientation of the object from the image information
may comprise
attaching to the object a tracking marker.
[00019] In another aspect there is provided a method for determining the
position and
orientation of a tracker with respect to a surgical site, the method
comprising the steps of:
applying proximate the surgical site an arbirtrarily arranged a plurality of
non-unique
elements, each element including one of radio-opaque ink and radio-opaque
paint, at least a
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portion of said plurality of elements defining a constellation; obtaining scan
data of the
surgical site; obtaining image information about the surgical site from a
tracker;determining a
postion and orientation of at least one of the plurality of elements in the
scan data and;
determining a postion and orientation of the constellation in the image
information; deriving
a three-dimensional transformation matrix to relate the multi-element fiducial
pattern to a
coordinate system of the surgical site based on the position and orientation
of the
constellation in the scan data and the position and orientation of the
constellation in the
image information; and determining the position and orientation of a tracker
with respect to
the surgical site. The step of applying the fiducial pattern may include
depositing one of a
radio-opaque ink and a radio-opaque paint in an arbitrary arrangement of
elements. The step
of depositing may comprise applying a surgical incise film to the skin over
the surgical site;
and depositing the one of radio-opaque ink and radio-opaque paint on the
surgical incise
film.
BRIEF DESCRIPTION OF THE DRAWINGS
[00020] The above mentioned and other features and objects of this
invention, and the
manner of attaining them, will become more apparent and the invention itself
will be better
understood by reference to the following description of an embodiment of the
invention
taken in conjunction with the accompanying drawings, wherein:
[00021] Figure 1 is a schematic diagrammatic view of a network system
in which
embodiments of the present invention may be utilized.
[00022] Figure 2 is a block diagram of a computing system (either a
server or client, or
both, as appropriate), with optional input devices (e.g., keyboard, mouse,
touch screen, etc.)
and output devices, hardware, network connections, one or more processors, and
memory/storage for data and modules, etc. which may be utilized as controller
and display in
conjunction with embodiments of the present invention.
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[00023] Figures 3A-J are drawings of hardware components of the
surgical monitoring
system according to embodiments of the invention.
[00024] Figures 4A-C is a flow chart diagram illustrating one
embodiment of the
registering method of the present invention.
[00025] Figure 5 is a drawing of a dental fiducial key with a tracking pole
and a dental
drill according to one embodiment of the present invention.
[00026] Figure 6 is a drawing of an endoscopic surgical site showing
the fiducial key,
endoscope, and biopsy needle according to another embodiment of the invention.
[00027] Figures 7A, 7B , 7C, 7D , 7E, and 7F are drawings of a multi-
element fiducial
pattern comprising a plurality of pattern segments in respectively a default
condition and a
condition in which the body of a patient has moved to change the mutual
spatial relation of
the pattern segments.
[00028] Figures 8A-C is a flow chart diagram illustrating one
embodiment of the
registering method of the present invention as applied to the multi-element
fiducial pattern of
Figures 7A and 7B.
[00029] Figures 9A, 9B, 9C and 9D are drawings of a multi-element
arbitrary pattern
comprising a plurality of pattern points in respectively a default condition
and a condition in
which the surgical site has changed thereby changing the mutual spatial
relation of pattern
segments.
[00030] Figure 10 is a flow chart diagram illustrating one embodiment of a
registering
method as applied to the arbitrary marker arrangement of Figures 9A and 9B
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[00031] Corresponding reference characters indicate corresponding
parts throughout
the several views. Although the drawings represent embodiments of the present
invention,
the drawings are not necessarily to scale and certain features may be
exaggerated in order to
better illustrate and explain the present invention. The flow charts and
screen shots are also
representative in nature, and actual embodiments of the invention may include
further
features or steps not shown in the drawings. The exemplification set out
herein illustrates an
embodiment of the invention, in one form, and such exemplifications are not to
be construed
as limiting the scope of the invention in any manner.
DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION
[00032] The embodiments disclosed below are not intended to be exhaustive
or limit
the invention to the precise form disclosed in the following detailed
description. Rather, the
embodiments are chosen and described so that others skilled in the art may
utilize their
teachings.
[00033] The detailed descriptions that follow are presented in part in
terms of
algorithms and symbolic representations of operations on data bits within a
computer
memory representing alphanumeric characters or other information. The hardware
components are shown with particular shapes and relative orientations and
sizes using
particular scanning techniques, although in the general case one of ordinary
skill recognizes
that a variety of particular shapes and orientations and scanning
methodologies may be used
within the teaching of the present disclosure. A computer generally includes a
processor for
executing instructions and memory for storing instructions and data, including
interfaces to
obtain and process imaging data. When a general-purpose computer has a series
of machine
encoded instructions stored in its memory, the computer operating on such
encoded
instructions may become a specific type of machine, namely a computer
particularly
configured to perform the operations embodied by the series of instructions.
Some of the
instructions may be adapted to produce signals that control operation of other
machines and
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thus may operate through those control signals to transform materials far
removed from the
computer itself. These descriptions and representations are the means used by
those skilled
in the art of data processing arts to most effectively convey the substance of
their work to
others skilled in the art.
[00034] An algorithm is here, and generally, conceived to be a self-
consistent
sequence of steps leading to a desired result. These steps are those requiring
physical
manipulations of physical quantities, observing and measuring scanned data
representative of
matter around the surgical site. Usually, though not necessarily, these
quantities take the
form of electrical or magnetic pulses or signals capable of being stored,
transferred,
transformed, combined, compared, and otherwise manipulated. It proves
convenient at
times, principally for reasons of common usage, to refer to these signals as
bits, values,
symbols, characters, display data, terms, numbers, or the like as a reference
to the physical
items or manifestations in which such signals are embodied or expressed to
capture the
underlying data of an image. It should be borne in mind, however, that all of
these and
similar terms are to be associated with the appropriate physical quantities
and are merely
used here as convenient labels applied to these quantities.
[00035] Some algorithms may use data structures for both inputting
information and
producing the desired result. Data structures greatly facilitate data
management by data
processing systems, and are not accessible except through sophisticated
software systems.
Data structures are not the information content of a memory, rather they
represent specific
electronic structural elements that impart or manifest a physical organization
on the
information stored in memory. More than mere abstraction, the data structures
are specific
electrical or magnetic structural elements in memory, which simultaneously
represent
complex data accurately, often data modeling physical characteristics of
related items, and
provide increased efficiency in computer operation.
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[00036] Further, the manipulations performed are often referred to in terms,
such as
comparing or adding, commonly associated with mental operations performed by a
human
operator. No such capability of a human operator is necessary, or desirable in
most cases, in
any of the operations described herein that form part of embodiments of the
present
invention; the operations are machine operations. Useful machines for
performing the
operations of embodiments of the present invention include general-purpose
digital
computers or other similar devices. In all cases the distinction between the
method
operations in operating a computer and the method of computation itself should
be
recognized. Some embodiments of the present invention relate to a method and
apparatus for
operating a computer in processing electrical or other (e.g., mechanical,
chemical) physical
signals to generate other desired physical manifestations or signals. The
computer operates
on software modules, which are collections of signals stored on a media that
represents a
series of machine instructions that enable the computer processor to perform
the machine
instructions that implement the algorithmic steps. Such machine instructions
may be the
actual computer code the processor interprets to implement the instructions,
or alternatively
may be a higher level coding of the instructions that is interpreted to obtain
the actual
computer code. The software module may also include a hardware component,
wherein
some aspects of the algorithm are performed by the circuitry itself rather as
a result of an
instruction.
[00037] Further embodiments of the present invention also relate to an
apparatus for
performing these operations. This apparatus may be specifically constructed
for the required
purposes or it may comprise a general-purpose computer as selectively
activated or
reconfigured by a computer program stored in the computer. The algorithms
presented
herein are not inherently related to any particular computer or other
apparatus unless
explicitly indicated as requiring particular hardware. In some cases, the
computer programs
may communicate or relate to other programs or equipments through signals
configured to
particular protocols, which may or may not require specific hardware or
programming to
interact. In particular, various general-purpose machines may be used with
programs written
in accordance with the teachings herein, or it may prove more convenient to
construct more
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specialized apparatus to perform the required method steps. The required
structure for a
variety of these machines will appear from the description below.
[00038] Embodiments of the present invention may deal with "object-
oriented"
software, and particularly with an "object-oriented" operating system. The
"object-oriented"
software is organized into "objects", each comprising a block of computer
instructions
describing various procedures ("methods") to be performed in response to
"messages" sent to
the object or "events" which occur with the object. Such operations include,
for example, the
manipulation of variables, the activation of an object by an external event,
and the
transmission of one or more messages to other objects. Often, but not
necessarily, a physical
object has a corresponding software object that may collect and transmit
observed data from
the physical device to the software system. Such observed data may be accessed
from the
physical object and/or the software object merely as an item of convenience;
therefore where
"actual data" is used in the following description, such "actual data" may be
from the
instrument itself or from the corresponding software object or module.
[00039] Messages are sent and received between objects having certain
functions and
knowledge to carry out processes. Messages are generated in response to user
instructions,
for example, by a user activating an icon with a "mouse" pointer generating an
event. Also,
messages may be generated by an object in response to the receipt of a
message. When one
of the objects receives a message, the object carries out an operation (a
message procedure)
corresponding to the message and, if necessary, returns a result of the
operation. Each object
has a region where internal states (instance variables) of the object itself
are stored and where
the other objects are not allowed to access. One feature of the object-
oriented system is
inheritance. For example, an object for drawing a "circle" on a display may
inherit functions
and knowledge from another object for drawing a "shape" on a display.
[00040] A programmer "programs" in an object-oriented programming language
by
writing individual blocks of code each of which creates an object by defining
its methods. A
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collection of such objects adapted to communicate with one another by means of
messages
comprises an object-oriented program. Object-oriented computer programming
facilitates
the modeling of interactive systems in that each component of the system may
be modeled
with an object, the behavior of each component being simulated by the methods
of its
corresponding object, and the interactions between components being simulated
by messages
transmitted between objects.
[00041] An operator may stimulate a collection of interrelated objects
comprising an
object-oriented program by sending a message to one of the objects. The
receipt of the
message may cause the object to respond by carrying out predetermined
functions, which
may include sending additional messages to one or more other objects. The
other objects
may in turn carry out additional functions in response to the messages they
receive, including
sending still more messages. In this manner, sequences of message and response
may
continue indefinitely or may come to an end when all messages have been
responded to and
no new messages are being sent. When modeling systems utilizing an object-
oriented
language, a programmer need only think in terms of how each component of a
modeled
system responds to a stimulus and not in terms of the sequence of operations
to be performed
in response to some stimulus. Such sequence of operations naturally flows out
of the
interactions between the objects in response to the stimulus and need not be
preordained by
the programmer.
[00042] Although object-oriented programming makes simulation of systems of
interrelated components more intuitive, the operation of an object-oriented
program is often
difficult to understand because the sequence of operations carried out by an
object-oriented
program is usually not immediately apparent from a software listing as in the
case for
sequentially organized programs. Nor is it easy to determine how an object-
oriented program
works through observation of the readily apparent manifestations of its
operation. Most of
the operations carried out by a computer in response to a program are
"invisible" to an
observer since only a relatively few steps in a program typically produce an
observable
computer output.
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[00043] In the following description, several terms that are used
frequently have
specialized meanings in the present context. The term "object" relates to a
set of computer
instructions and associated data, which may be activated directly or
indirectly by the user.
The terms "windowing environment", "running in windows", and "object oriented
operating
system" are used to denote a computer user interface in which information is
manipulated
and displayed on a video display such as within bounded regions on a raster
scanned video
display. The terms "network", "local area network", "LAN", "wide area
network", or
"WAN" mean two or more computers that are connected in such a manner that
messages may
be transmitted between the computers. In such computer networks, typically one
or more
computers operate as a "server", a computer with large storage devices such as
hard disk
drives and communication hardware to operate peripheral devices such as
printers or
modems. Other computers, termed "workstations", provide a user interface so
that users of
computer networks may access the network resources, such as shared data files,
common
peripheral devices, and inter-workstation communication. Users activate
computer programs
or network resources to create "processes" which include both the general
operation of the
computer program along with specific operating characteristics determined by
input variables
and its environment. Similar to a process is an agent (sometimes called an
intelligent agent),
which is a process that gathers information or performs some other service
without user
intervention and on some regular schedule. Typically, an agent, using
parameters typically
provided by the user, searches locations either on the host machine or at some
other point on
a network, gathers the information relevant to the purpose of the agent, and
presents it to the
user on a periodic basis.
[00044] The term "desktop" means a specific user interface which
presents a menu or
display of objects with associated settings for the user associated with the
desktop. When the
desktop accesses a network resource, which typically requires an application
program to
execute on the remote server, the desktop calls an Application Program
Interface, or "API",
to allow the user to provide commands to the network resource and observe any
output. The
term "Browser" refers to a program which is not necessarily apparent to the
user, but which is
responsible for transmitting messages between the desktop and the network
server and for
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displaying and interacting with the network user. Browsers are designed to
utilize a
communications protocol for transmission of text and graphic information over
a worldwide
network of computers, namely the "World Wide Web" or simply the "Web".
Examples of
Browsers compatible with embodiments of the present invention include the
Internet
Explorer program sold by Microsoft Corporation (Internet Explorer is a
trademark of
Microsoft Corporation), the Opera Browser program created by Opera Software
ASA, or the
Firefox browser program distributed by the Mozilla Foundation (Firefox is a
registered
trademark of the Mozilla Foundation). Although the following description
details such
operations in terms of a graphic user interface of a Browser, embodiments of
the present
invention may be practiced with text based interfaces, or even with voice or
visually
activated interfaces, that have many of the functions of a graphic based
Browser.
[00045] Browsers display information, which is formatted in a Standard
Generalized
Markup Language ("SGML") or a HyperText Markup Language ("HTML"), both being
scripting languages, which embed non-visual codes in a text document through
the use of
special ASCII text codes. Files in these formats may be easily transmitted
across computer
networks, including global information networks like the Internet, and allow
the Browsers to
display text, images, and play audio and video recordings. The Web utilizes
these data file
formats to conjunction with its communication protocol to transmit such
information
between servers and workstations. Browsers may also be programmed to display
information provided in an eXtensible Markup Language ("XML") file, with XML
files
being capable of use with several Document Type Definitions ("DTD") and thus
more
general in nature than SGML or HTML. The XML file may be analogized to an
object, as
the data and the stylesheet formatting are separately contained (formatting
may be thought of
as methods of displaying information, thus an XML file has data and an
associated method).
[00046] The terms "personal digital assistant" or "PDA", as defined above,
means any
handheld, mobile device that combines computing, telephone, fax, e-mail and
networking
features. The terms "wireless wide area network" or "WWAN" mean a wireless
network that
serves as the medium for the transmission of data between a handheld device
and a computer.
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The term "synchronization" means the exchanging of information between a first
device, e.g.
a handheld device, and a second device, e.g. a desktop computer, either via
wires or
wirelessly. Synchronization ensures that the data on both devices are
identical (at least at the
time of synchronization).
[00047] In wireless wide area networks, communication primarily occurs
through the
transmission of radio signals over analog, digital cellular, or personal
communications
service ("PCS") networks. Signals may also be transmitted through microwaves
and other
electromagnetic waves. At the present time, most wireless data communication
takes place
across cellular systems using second generation technology such as code-
division multiple
access ("CDMA"), time division multiple access ("TDMA"), the Global System for
Mobile
Communications ("GSM"), Third Generation (wideband or "3G"), Fourth Generation
(broadband or "4G"), personal digital cellular ("PDC"), or through packet-data
technology
over analog systems such as cellular digital packet data (CDPD") used on the
Advance
Mobile Phone Service ("AMPS").
[00048] The terms "wireless application protocol" or "WAP" mean a universal
specification to facilitate the delivery and presentation of web-based data on
handheld and
mobile devices with small user interfaces. "Mobile Software" refers to the
software
operating system, which allows for application programs to be implemented on a
mobile
device such as a mobile telephone or PDA. Examples of Mobile Software are Java
and Java
ME (Java and JavaME are trademarks of Sun Microsystems, Inc. of Santa Clara,
California),
BREW (BREW is a registered trademark of Qualcomm Incorporated of San Diego,
California), Windows Mobile (Windows is a registered trademark of Microsoft
Corporation
of Redmond, Washington), Palm OS (Palm is a registered trademark of Palm, Inc.
of
Sunnyvale, California), Symbian OS (Symbian is a registered trademark of
Symbian
Software Limited Corporation of London, United Kingdom), ANDROID OS (ANDROID
is
a registered trademark of Google, Inc. of Mountain View, California), and
iPhone OS
(iPhone is a registered trademark of Apple, Inc. of Cupertino, California) ,
and Windows
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Phone 7. "Mobile Apps" refers to software programs written for execution with
Mobile
Software.
[00049] The terms "scan," "fiducial reference", "fiducial location",
"marker,"
"tracker" and "image information" have particular meanings in the present
disclosure. For
purposes of the present disclosure, "scan" or derivatives thereof refer to x-
ray, magnetic
resonance imaging (MRI), computerized tomography (CT), sonography, cone beam
computerized tomography (CBCT), or any system that produces a quantitative
spatial
representation of a patient. The term "fiducial reference" or simply
"fiducial" refers to an
object or reference on the image of a scan that is uniquely identifiable as a
fixed recognizable
point. In the present specification the term "fiducial location" refers to a
useful location to
which a fiducial reference is attached. A "fiducial location" will typically
be proximate a
surgical site. The term "marker" or "tracking marker" refers to an object or
reference that
may be perceived by a sensor proximate to the location of the surgical or
dental procedure,
where the sensor may be an optical sensor, a radio frequency identifier
(RFID), a sonic
motion detector, an ultra-violet or infrared sensor. The term "tracker" refers
to a device or
system of devices able to determine the location of the markers and their
orientation and
movement continually in 'real time' during a procedure. As an example of a
possible
implementation, if the markers are composed of printed targets then the
tracker may include
a stereo camera pair. The term "image information" is used in the present
specification to
describe information obtained by the tracker, whether optical or otherwise,
and usable for
determining the location of the markers and their orientation and movement
continually in
'real time' during a procedure.
[00050] Figure 1 is a high-level block diagram of a computing
environment 100
according to one embodiment. Figure 1 illustrates server 110 and three clients
112 connected
by network 114. Only three clients 112 are shown in Figure 1 in order to
simplify and clarify
the description. Embodiments of the computing environment 100 may have
thousands or
millions of clients 112 connected to network 114, for example the Internet.
Users (not
shown) may operate software 116 on one of clients 112 to both send and receive
messages
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network 114 via server 110 and its associated communications equipment and
software (not
shown).
[00051] Figure 2 depicts a block diagram of computer system 210
suitable for
implementing server 110 or client 112. Computer system 210 includes bus 212
which
interconnects major subsystems of computer system 210, such as central
processor 214,
system memory 217 (typically RAM, but which may also include ROM, flash RAM,
or the
like), input/output controller 218, external audio device, such as speaker
system 220 via
audio output interface 222, external device, such as display screen 224 via
display adapter
226, serial ports 228 and 230, keyboard 232 (interfaced with keyboard
controller 233),
storage interface 234, disk drive 237 operative to receive floppy disk 238,
host bus adapter
(HBA) interface card 235A operative to connect with Fibre Channel network 290,
host bus
adapter (HBA) interface card 235B operative to connect to SCSI bus 239, and
optical disk
drive 240 operative to receive optical disk 242. Also included are mouse 246
(or other point-
and-click device, coupled to bus 212 via serial port 228), modem 247 (coupled
to bus 212 via
serial port 230), and network interface 248 (coupled directly to bus 212).
[00052] Bus 212 allows data communication between central processor
214 and
system memory 217, which may include read-only memory (ROM) or flash memory
(neither
shown), and random access memory (RAM) (not shown), as previously noted. RAM
is
generally the main memory into which operating system and application programs
are
loaded. ROM or flash memory may contain, among other software code, Basic
Input-Output
system (BIOS), which controls basic hardware operation such as interaction
with peripheral
components. Applications resident with computer system 210 are generally
stored on and
accessed via computer readable media, such as hard disk drives (e.g., fixed
disk 244), optical
drives (e.g., optical drive 240), floppy disk unit 237, or other storage
medium. Additionally,
applications may be in the form of electronic signals modulated in accordance
with the
application and data communication technology when accessed via network modem
247 or
interface 248 or other telecommunications equipment (not shown).
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[00053] Storage interface 234, as with other storage interfaces of
computer system
210, may connect to standard computer readable media for storage and/or
retrieval of
information, such as fixed disk drive 244. Fixed disk drive 244 may be part of
computer
system 210 or may be separate and accessed through other interface systems.
Modem 247
may provide direct connection to remote servers via telephone link or the
Internet via an
Internet service provider (ISP) (not shown). Network interface 248 may provide
direct
connection to remote servers via direct network link to the Internet via a POP
(point of
presence). Network interface 248 may provide such connection using wireless
techniques,
including digital cellular telephone connection, Cellular Digital Packet Data
(CDPD)
connection, digital satellite data connection or the like.
[00054] Many other devices or subsystems (not shown) may be connected
in a similar
manner (e.g., document scanners, digital cameras and so on), including the
hardware
components of Figures 3A-I, which alternatively may be in communication with
associated
computational resources through local, wide-area, or wireless networks or
communications
systems. Thus, while the disclosure may generally discuss an embodiment where
the
hardware components are directly connected to computing resources, one of
ordinary skill in
this area recognizes that such hardware may be remotely connected with
computing
resources. Conversely, all of the devices shown in Figure 2 need not be
present to practice
the present disclosure. Devices and subsystems may be interconnected in
different ways
from that shown in Figure 2. Operation of a computer system such as that shown
in Fig. 2 is
readily known in the art and is not discussed in detail in this application.
Software source
and/or object codes to implement the present disclosure may be stored in
computer-readable
storage media such as one or more of system memory 217, fixed disk 244,
optical disk 242,
or floppy disk 238. The operating system provided on computer system 210 may
be a variety
or version of either MS-DOS (MS-DOS is a registered trademark of Microsoft
Corporation
of Redmond, Washington), WINDOWS (WINDOWS is a registered trademark of
Microsoft Corporation of Redmond, Washington), OS/20 (0S/2 is a registered
trademark of
International Business Machines Corporation of Armonk, New York), UNIX (UNIX
is a
registered trademark of X/Open Company Limited of Reading, United Kingdom),
Linux
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(Linux is a registered trademark of Linus Torvalds of Portland, Oregon), or
other known or
developed operating system.
[00055] Moreover, regarding the signals described herein, those
skilled in the art
recognize that a signal may be directly transmitted from a first block to a
second block, or a
signal may be modified (e.g., amplified, attenuated, delayed, latched,
buffered, inverted,
filtered, or otherwise modified) between blocks. Although the signals of the
above-described
embodiments are characterized as transmitted from one block to the next, other
embodiments
of the present disclosure may include modified signals in place of such
directly transmitted
signals as long as the informational and/or functional aspect of the signal is
transmitted
between blocks. To some extent, a signal input at a second block may be
conceptualized as a
second signal derived from a first signal output from a first block due to
physical limitations
of the circuitry involved (e.g., there will inevitably be some attenuation and
delay).
Therefore, as used herein, a second signal derived from a first signal
includes the first signal
or any modifications to the first signal, whether due to circuit limitations
or due to passage
through other circuit elements which do not change the informational and/or
final functional
aspect of the first signal.
[00056] Embodiments of the present invention relate to a surgical
hardware and
software monitoring system and method which allows for surgical planning while
the patient
is available for surgery, for example while the patient is being prepared for
surgery so that
the system may model the surgical site. In one implementation the system uses
a particularly
configured piece of hardware, represented as fiducial key 10 in Figure 3A, to
orient tracking
marker 12 of the monitoring system with regard to the critical area of the
surgery. Fiducial
key 10 is attached to a location near the intended surgical area, in the
exemplary embodiment
of the dental surgical area of Figure 3A, fiducial key 10 is attached to a
dental splint 14.
Tracking marker 12 may be connected to fiducial key 10 by tracking pole 11. In
embodiments in which the fiducial reference is directly visible to a suitable
tracker (see for
example Figure 5 and Figure 6) that acquires image information about the
surgical site, a
tracking marker may be attached directly to the fiducial reference. For
example a dental
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surgery, the dental tracking marker 14 may be used to securely locate the
fiducial 10 near the
surgical area. The fiducial key 10 may be used as a point of reference, or a
fiducial, for the
further image processing of data acquired from tracking marker 12 by the
tracker.
[00057] In other embodiments additional tracking markers 12 may be
attached to items
independent of the fiducial key 10 and any of its associated tracking poles 11
or tracking
markers 12. This allows the independent items to be tracked by the tracker.
[00058] In a further embodiment at least one of the items or
instruments near the
surgical site may optionally have a tracker attached to function as tracker
for the monitoring
system of embodiments of the invention and to thereby sense the orientation
and the position
of the tracking marker 12 and of any other additional tracking markers
relative to the scan
data of the surgical area. By way of example, the tracker attached to an
instrument may be a
miniature digital camera and it may be attached, for example, to a dentist's
drill. Any other
markers to be tracked by the tracker attached to the item or instrument must
be within the
field of view of the tracker.
[00059] Using the dental surgery example, the patient is scanned to obtain
an initial
scan of the surgical site. The particular configuration of fiducial key 10
allows computer
software stored in memory and executed in a suitable controller, for example
processor 214
and memory 217 of computer 210 of Figure 2, to recognize its relative position
within the
surgical site from the scan data, so that further observations may be made
with reference to
both the location and orientation of fiducial key 10. In some embodiments, the
fiducial
reference includes a marking that is apparent as a recognizable identifying
symbol when
scanned. In other embodiments, the fiducial reference includes a shape that is
distinct in the
sense that the body apparent on the scan has an asymmetrical form allowing the
front, rear,
upper, and lower, and left/right defined surfaces that may be unambiguously
determined from
the analysis of the scan, thereby to allow the determination not only of the
location of the
fiducial reference, but also of its orientation.
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[00060] In addition, the computer software may create a coordinate
system for
organizing objects in the scan, such as teeth, jaw bone, skin and gum tissue,
other surgical
instruments, etc. The coordinate system relates the images on the scan to the
space around
the fiducial and locates the instruments bearing markers both by orientation
and position.
The model generated by the monitoring system may then be used to check
boundary
conditions, and in conjunction with the tracker display the arrangement in
real time on a
suitable display, for example display 224 of Figure 2.
[00061] In one embodiment, the computer system has a predetermined
knowledge of
the physical configuration of fiducial key 10 and examines slices/sections of
the scan to
locate fiducial key 10. Locating of fiducial key 10 may be on its distinct
shape, or on the
basis of distinctive identifying and orienting markings upon the fiducial key
or on
attachments to the fiducial key 10 as tracking marker 12. Fiducial key 10 may
be rendered
distinctly visible in the scans through higher imaging contrast by the employ
of radio-opaque
materials or high-density materials in the construction of the fiducial key
10. In other
embodiments the material of the distinctive identifying and orienting markings
may be
created using suitable high density or radio-opaque inks or materials.
[00062] Once fiducial key 10 is identified, the location and
orientation of the fiducial
key 10 is determined from the scan segments, and a point within fiducial key
10 is assigned
as the center of the coordinate system. The point so chosen may be chosen
arbitrarily, or the
choice may be based on some useful criterion. A model is then derived in the
form of a
transformation matrix to relate the fiducial system, being fiducial key 10 in
one particular
embodiment, to the coordinate system of the surgical site. The resulting
virtual construct may
be used by surgical procedure planning software for virtual modeling of the
contemplated
procedure, and may alternatively be used by instrumentation software for the
configuration
of the instrument, for providing imaging assistance for surgical software,
and/or for plotting
trajectories for the conduct of the surgical procedure.
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[00063] In some embodiments, the monitoring hardware includes a
tracking
attachment to the fiducial reference. In the embodiment pertaining to dental
surgery the
tracking attachment to fiducial key 10 is tracking marker 12, which is
attached to fiducial key
via tracking pole 11. Tracking marker 12 may have a particular identifying
pattern. The
5 trackable attachment, for example tracking marker 12, and even associated
tracking pole 11
may have known configurations so that observational data from tracking pole 11
and/or
tracking marker 12 may be precisely mapped to the coordinate system, and thus
progress of
the surgical procedure may be monitored and recorded. For example, as
particularly shown
in Figure 3J, fiducial key 10 may have hole 15 in a predetermined location
specially adapted
10 for engagement with insert 17 of tracking pole 11. In such an
arrangement, for example,
tracking poles 11 may be attached with a low force push into hole 15 of
fiducial key 10, and
an audible haptic notification may thus be given upon successful completion of
the
attachment.
[00064] It is further possible to reorient the tracking pole during a
surgical procedure.
Such reorientation may be in order to change the location of the procedure,
for example
where a dental surgery deals with teeth on the opposite side of the mouth,
where a surgeon
switches hands, and/or where a second surgeon performs a portion of the
procedure. For
example, the movement of the tracking pole may trigger a re-registration of
the tracking pole
with relation to the coordinate system, so that the locations may be
accordingly adjusted.
Such a re-registration may be automatically initiated when, for example in the
case of the
dental surgery embodiment, tracking pole 11 with its attached tracking marker
12 are
removed from hole 15 of fiducial key 10 and another tracking marker with its
associated
tracking pole is connected to an alternative hole on fiducial key 10.
Additionally, boundary
conditions may be implemented in the software so that the user is notified
when
observational data approaches and /or enters the boundary areas.
[00065] In a further embodiment, a surgical instrument or implement,
herein termed a
"hand piece" (see Figures 5 and 6), may also have a particular configuration
that may be
located and tracked in the coordinate system and may have suitable tracking
markers as
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described herein. A boundary condition may be set up to indicate a potential
collision with
virtual material, so that when the hand piece is sensed to approach the
boundary condition an
indication may appear on a screen, or an alarm sound. Further, target boundary
conditions
may be set up to indicate the desired surgical area, so that when the
trajectory of the hand
piece is trending outside the target area an indication may appear on screen
or an alarm sound
indicating that the hand piece is deviating from its desired path.
[00066] An alternative embodiment of some hardware components are
shown in
Figures 3G-I. Fiducial key 10' has connection elements with suitable
connecting portions to
allow a tracking pole 11' to position a tracking marker 12' relative to the
surgical site.
Conceptually, fiducial key 10' serves as an anchor for pole 11' and tracking
marker 12' in
much the same way as the earlier embodiment, although it has a distinct shape.
The software
of the monitoring system is pre-programmed with the configuration of each
particularly
identified fiducial key, tracking pole, and tracking marker, so that the
location calculations
are only changed according to the changed configuration parameters.
[00067] The materials of the hardware components may vary according to
regulatory
requirements and practical considerations. Generally, the key or fiducial
component is made
of generally radio opaque material such that it does not produce noise for the
scan, yet
creates recognizable contrast on the scanned image so that any identifying
pattern associated
with it may be recognized. In addition, because it is generally located on the
patient, the
material should be lightweight and suitable for connection to an apparatus on
the patient. For
example, in the dental surgery example, the materials of the fiducial key must
be suitable for
connection to a plastic splint and suitable for connection to a tracking pole.
In the surgical
example the materials of the fiducial key may be suitable for attachment to
the skin or other
particular tissue of a patient.
[00068] The tracking markers are clearly identified by employing, for
example without
limitation, high contrast pattern engraving. The materials of the tracking
markers are chosen
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to be capable of resisting damage in autoclave processes and are compatible
with rigid,
repeatable, and quick connection to a connector structure. The tracking
markers and
associated tracking poles have the ability to be accommodated at different
locations for
different surgery locations, and, like the fiducial keys, they should also be
relatively
lightweight as they will often be resting on or against the patient. The
tracking poles must
similarly be compatible with autoclave processes and have connectors of a form
shared
among tracking poles.
[00069] The tracker employed in tracking the fiducial keys, tracking
poles and
tracking markers should be capable of tracking with suitable accuracy objects
of a size of the
order of 1.5 square centimeters. The tracker may be, by way of example without
limitation, a
stereo camera or stereo camera pair. While the tracker is generally connected
by wire to a
computing device to read the sensory input, it may optionally have wireless
connectivity to
transmit the sensory data to a computing device.
[00070] In embodiments that additionally employ a trackable piece of
instrumentation,
such as a hand piece, tracking markers attached to such a trackable piece of
instrumentation
may also be light-weight; capable of operating in a 3D object array with 90
degrees
relationship; optionally having a high contrast pattern engraving and a rigid,
quick mounting
mechanism to a standard hand piece.
[00071] In another aspect there is presented an automatic registration
method for
tracking surgical activity, as illustrated in Figures 4A-C. Figure 4A and
Figure 4B together
present, without limitation, a flowchart of one method for determining the
three-dimensional
location and orientation of the fiducial reference from scan data. Figure 4C
presents a flow
chart of a method for confirming the presence of a suitable tracking marker in
image
information obtained by the tracker and determining the three-dimensional
location and
orientation of the fiducial reference based on the image information.
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[00072] Once the process starts [402], as described in Figures 4A and
4B, the system
obtains a scan data set [404] from, for example, a CT scanner and checks for a
default CT
scan Hounsfield unit (HU) value [at 406] for the fiducial which may or may not
have been
provided with the scan based on a knowledge of the fiducial and the particular
scanner
model, and if such a threshold value is not present, then a generalized
predetermined default
value is employed [408]. Next the data is processed by removing scan segments
with
Hounsfield data values outside expected values associated with the fiducial
key values [at
410], following the collection of the remaining points [at 412]. If the data
is empty [at 414],
the CT value threshold is adjusted [at 416], the original value restored [at
418], and the
segmenting processing scan segments continues [at 410]. Otherwise, with the
existing data a
center of mass is calculated [at 420], along with calculating the X, Y, and Z
axes [at 422]. If
the center of mass is not at the cross point of the XYZ axes [at 424], then
the user is notified
[at 426] and the process stopped [at 428]. If the center of mass is at the XYZ
cross point
then the data points are compared with the designed fiducial data [430]. If
the cumulative
error is larger than the maximum allowed error [432] then the user is notified
[at 434] and
the process ends [at 436]. If not, then the coordinate system is defined at
the XYZ cross
point [at 438], and the scan profile is updated for the HU units [at 440].
[00073] Turning now to Figure 4C, an image is obtained from the
tracker, being a
suitable camera or other sensor [442]. The image information is analyzed to
determine
whether a tracking marker is present in the image information [444]. If not,
then the user is
queried [446] as to whether the process should continue or not. If not, then
the process is
ended [448]. If the process is to continue, then the user can be notified that
no tracking
marker has been found in the image information [450], and the process returns
to obtaining
image information [442]. If a tracking marker has been found based on the
image
information, or one has been attached by the user upon the above notification
[450], the
offset and relative orientation of the tracking marker to the fiducial
reference is obtained
from a suitable database [452]. The term "database" is used in this
specification to describe
any source, amount or arrangement of such information, whether organized into
a formal
multi-element or multi-dimensional database or not. A single data set
comprising offset value
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and relative orientation may suffice in a simple implementation of this
embodiment and may
be provided, for example, by the user or may be within a memory unit of the
controller or in
a separate database or memory.
[00074] The offset and relative orientation of the tracking marker is
used to define the
origin of a coordinate system at the fiducial reference and to determine the
three-dimensional
orientation of the fiducial reference based on the image information [454] and
the registration
process ends [458]. In order to monitor the location and orientation of the
fiducial reference
in real time, the process may be looped back from step [454] to obtain new
image
information from the camera [442]. A suitable query point may be included to
allow the user
to terminate the process. Detailed methods for determining orientations and
locations of
predetermined shapes or marked tracking markers from image data are known to
practitioners of the art and will not be dwelt upon here. The coordinate
system so derived is
then used for tracking the motion of any items bearing tracking markers in the
proximity of
the surgical site. Other registration systems are also contemplated, for
example using current
other sensory data rather than the predetermined offset, or having a fiducial
with a
transmission capacity.
[00075] One exemplary embodiment is shown in Figure 5. In addition to
fiducial key
502 mounted at a predetermined tooth and having a rigidly mounted tracking
marker 504, an
additional instrument or implement 506, for example a hand piece which may be
a dental
drill, may be observed by a camera 508 serving as tracker of the monitoring
system.
[00076] Another exemplary embodiment is shown in Figure 6. Surgery
site 600, for
example a human stomach or chest, may have fiducial key 602 fixed to a
predetermined
position to support tracking marker 604. Endoscope 606 may have further
tracking markers,
and biopsy needle 608 may also be present bearing a tracking marker at surgery
site 600.
Sensor 610 may be for example a camera, infrared sensing device, or RADAR.
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[00077] In another embodiment, shown schematically in Figure 7A, the
fiducial key
may comprise a multi-element fiducial pattern 710. In one implementation the
multi-element
fiducial pattern 710 may be a dissociable pattern. The term "dissociable
pattern" is used in
this specification to describe a pattern comprising a plurality of pattern
segments 720 that
topologically fit together to form a contiguous whole pattern, and which may
temporarily be
separated from one another, either in whole or in part. The term "breakable
pattern" is used
as an alternative term to describe such a dissociable pattern. In other
implementations the
segments of the multi-element fiducial pattern 710 do not form a contiguous
pattern, but
instead their positions and orientations with respect to one another are known
when the
multi-element fiducial pattern 710 is applied on the body of the patient near
a critical area of
a surgical site. Each pattern segment 720 is individually locatable based on
scan data of a
surgical site to which multi-element fiducial pattern 710 may be attached.
[00078] Pattern segments 720 are uniquely identifiable by tracker 730,
being
differentiated from one another in one or more of a variety of ways. Pattern
segments 720
may be mutually differentiable shapes that also allow the identification of
their orientations.
Pattern segments 720 may be uniquely marked in one or more of a variety of
ways, including
but not limited to barcoding or orientation-defining symbols. The marking may
be directly
on the pattern segments 720, or may be on tracking markers 740 attached to
pattern segments
720. The marking may be accomplished by a variety of methods, including but
not limited to
engraving and printing. In the embodiment shown in Figures 7A and 7B, by way
of non-
limiting example, the letters F, G, J, L, P, Q and R have been used.
[00079] The materials of the multi-element fiducial pattern 710 and
pattern segments
720, and of any tracking markers 740 attached to them, may vary according to
regulatory
requirements and practical considerations. Generally, the key or fiducial
component is made
of generally radio opaque material such that it does not produce noise for the
scan, yet
creates recognizable contrast on the scanned image so that any identifying
pattern associated
with it may be recognized. The multi-element fiducial pattern 710 and pattern
segments 720
may have a distinct coloration difference from human skin in order to be more
clearly
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differentiable by tracker 730. In addition, because it is generally located on
the patient, the
material should be lightweight. The materials should also be capable of
resisting damage in
autoclave processes.
[00080] A suitable tracker of any of the types already described is
used to locate and
image multi-element fiducial pattern 710 within the surgical area. Multi-
element fiducial
pattern 710 may be rendered distinctly visible in scans of the surgical area
through higher
imaging contrast by the employ of radio-opaque materials or high-density
materials in the
construction of the multi-element fiducial pattern 710. In other embodiments
the distinctive
identifying and orienting markings on the pattern segments 720 or on the
tracking markers
740 may be created using suitable high-density materials or radio-opaque inks,
thereby
allowing the orientations of pattern segments 720 to be determined based on
scan data.
[00081] During surgery the surgical area may undergo changes in
position and
orientation. This may occur, for example, as a result of the breathing or
movement of the
patient. In this process, as shown in Figure 7B, pattern segments 720 of multi-
element
fiducial pattern 710 change their relative locations and also, in general,
their relative
orientations. Information on these changes may be used to gain information on
the
subcutaneous motion of the body of the patient in the general vicinity of the
surgical site by
relating the changed positions and orientations of pattern segments 720 to
their locations and
orientations in a scan done before surgery.
[00082] Using abdominal surgery as example, the patient is scanned, for
example by
an x-ray, magnetic resonance imaging (MRI), computerized tomography (CT), or
cone beam
computerized tomography (CBCT), to obtain an initial image of the surgical
site. The
particular configuration of multi-element fiducial pattern 710 allows computer
software to
recognize its relative position within the surgical site, so that further
observations may be
made with reference to both the location and orientation of multi-element
fiducial pattern
710. In fact, the computer software may create a coordinate system for
organizing objects in
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the scan, such as skin, organs, bones, and other tissue, other surgical
instruments bearing
suitable tracking markers, and segments 720 of multi-element fiducial pattern
710 etc.
[00083] In one embodiment, the computer system has a predetermined
knowledge of
the configuration of multi-element fiducial pattern 710 and examines slices of
a scan of the
surgical site to locate pattern segments 720 of multi-element fiducial pattern
710 based on
one or more of the radio-opacity density of the material of the pattern
segments 720, their
shapes and their unique tracking markers 740. Once the locations and
orientations of the
pattern segments 720 have been determined, a point within or near multi-
element fiducial
pattern 710 is assigned as the center of the coordinate system. The point so
chosen may be
chosen arbitrarily, or the choice may be based on some useful criterion. A
transformation
matrix is derived to relate multi-element fiducial pattern 710 to the
coordinate system of the
surgical site. The resulting virtual construct may then be used by surgical
procedure
planning software for virtual modeling of the contemplated procedure, and may
alternatively
be used by instrumentation software for the configuration of the instrument,
for providing
imaging assistance for surgical software, and/or for plotting trajectories for
the conduct of the
surgical procedure.
[00084] Multi-element fiducial pattern 710 changes its shape as the
body moves
during surgery. The relative locations and relative orientations of pattern
segments 720
change in the process (see Figure 7A relative to Figure 7B). In this process
the integrity of
individual pattern segments 720 is maintained and they may be tracked by
tracker 730,
including but not limited to a stereo video camera. The changed multi-element
fiducial
pattern 710' may be compared with initial multi-element fiducial pattern 710'
to create a
transformation matrix. The relocating and reorienting of pattern segments 720
may therefore
be mapped on a continuous basis within the coordinate system of the surgical
site. In the
exemplary embodiment of Figures 7A and 7B, a total of seven pattern segments
720 are
shown. In other embodiments multi-element fiducial pattern 710 may comprise
larger or
smaller numbers of pattern segments 720. During operation of the surgical
monitoring
system of this embodiment a selection of pattern segments 720 may be employed
and there is
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no limitation that all pattern segments 720 of multi-element fiducial pattern
710 have to be
employed. The decision as to how many pattern segments 720 to employ may, by
way of
example, be based on the resolution required for the surgery to be done or on
the processing
speed of the controller, which may be, for example, computer 210 of Figure 2.
[00085] For the sake of clarity, Figure 7A employs a dissociable multi-
element
fiducial pattern. In other embodiments the multi-element fiducial pattern may
have a
dissociated fiducial pattern, such as that of Figure 7B, as default. The
individual pattern
segments 720 then change position as the body of the patient changes shape
near the surgical
site during the surgery. In yet other embodiments, for example Figures 7C and
7D, multi-
element fiducial patterns 752 and 752' do not include tracking markers 740 and
the tracking
system, including tracker 758, may rely on tracking pattern segments 754
purely on the basis
of their unique shapes, which lend themselves to determining orientation due
to a lack of a
center of symmetry. As already pointed out, in other embodiments pattern
segments 720
may not be in general limited to being capable of being joined topologically
at their
perimeters to form a contiguous surface. Nor is there a particular limitation
on the general
shape of the multi-element fiducial pattern.
[00086] In a further embodiment, for example in Figures 7E and 7F,
multi-element
fiducial pattern 762 and 762' may comprise of individual pattern segments 764
composed of
a marking of a contrast material that produces suitable contrast in a scan of
the surgical site
and which may be applied to surgical incise film material 766. This embodiment
does not
require tracking markers 740 of Figures 7A and 7B. The contrast material may,
in one
embodiment, be an ink or paint having radio-opaque properties to produce the
suitable
contrast for scans, and be visible to tracker 768. The surgical incise film
may be, for
example without limitation, IobanTM 2 Antimicrobial Incise Film from 3M
Incorporated of
St. Paul, MN, or a similar surgical incise film capable of bearing an scan-
locatable ink
pattern. The ink or paint marking may be applied in the shape of the
individual pattern
segments 764 using a suitable stencil or may be pre-manufactured on the
surgical incise film.
The application of the fiducial reference to the fiducial location on the skin
proximate the
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surgical site may comprise applying surgical incise film 766 to the skin over
the surgical site
and then transferring the marking of a multi-element scan locatable ink
fiducial pattern to the
surgical incise film proximate the surgical site. This implementation
employing a surgical
incise film holds the benefit of placing fiducial pattern 762 in the closest
possible proximity
to the surgical site, as the first surgical incision during the surgery is
made through the
surgical incise film.
[00087] In yet a further embodiment, the radio-opaque ink or paint
marking may be
applied directly to the skin of the patient proximate the surgical site in
order to create multi-
element fiducial pattern 710 comprising individual pattern segments 720. The
suitable ink or
paint may have suitable radio-opaque properties to produce the suitable
contrast to render it
scan-locatable and conforms to regulatory requirements. The ink or paint may
be applied
directly to the skin in the shape of the individual pattern segments 720 using
a suitable
stencil.
[00088] In a further embodiment the ink or paint marking may be
applied as a transfer
pattern from an inked transfer tape applied to the skin, as described in
United States Patent.
No. 5,743,899 to Zinreich et al or Patent Cooperation Treaty application WO
2011/094833A1 by Aeos Biomedical Inc. of Vancouver, British Columbia, the
disclosures of
which are explicitly incorporated by reference herein.
[00089] The radio-opaque marking may be, for example without
limitation, the heavy
metal based ink described in general by United States Patent Application U.S.
2004/0127824A1 by Falahee et al. ("Falahee" hereinafter), the disclosure of
which is hereby
explicitly incorporated by reference herein. A suitable ink may, without
limitation, include
barium heavy metal. A suitable ink composition for both x-ray tomography and
nuclear
magnetic resonance imaging diagnostic purposes is disclosed in U.S. Pat. No.
4,916,170
issued to Nambu et al. ("Nambu" hereinafter), the disclosure of which is
hereby explicitly
incorporated by reference herein. As disclosed in Nambu, the skin marker
composition that
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may be employed in the present disclosed embodiments may be comprised of a
radioopaque
material for x-ray diagnostic purposes and/or a non-magnetic hydrogel for
magnetic
resonance imaging purposes.
[00090] In the cases of the transfer pattern and the surgical incise
film, pattern
segments 720, 754 and 764 may be incorporated on the transfer material or tape
and on the
incise film, respectively, during their manufacture. In these two distinct
implementations,
pattern segments 720, 754, and 764 are predetermined, but sufficient pattern
segments 720,
754, and 764 may be prepared during manufacture to allow the surgeon or system
operator a
choice of which pattern segments 720, 754, and 764 to employ during surgery,
as already
explained with regard to Figure 7.
[00091] Another aspect of embodiments of the present invention involve
an automatic
registration method for tracking surgical activity using multi-element
fiducial pattern 710, as
shown in the flow chart diagram of Figure 8, encompassing Figures 8A, 8B and
8C. Figure
8A and Figure 8B together present, without limitation, a flowchart
representation of one
method for determining the three-dimensional location and orientation of one
segment of
multi-element fiducial pattern 710 from scan data. Figure 8C presents a flow
chart
representation of a method for determining the spatial distortion of the
surgical site based on
the changed orientations and locations of pattern segments 720 of multi-
element fiducial
pattern 710, using as input the result of applying the method shown in Figure
8A and Figure
8B to every one of pattern segments 720 that is to be employed in determining
the spatial
distortion of the surgical site. In principle, not all pattern segments 720
need to be employed.
[00092] Once the process starts [802], as described in Figures 8A and
8B, the system
obtains scan data set [404] from, for example, a CT scanner and checks for
default CT scan
Hounsfield unit (HU) value [806] for the fiducial, which may or may not have
been provided
with the scan based on a knowledge of the fiducial and the particular scanner
model. If such
a default value is not present, then a generalized predetermined system
default value is
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employed [808]. Next the data is processed by removing scan slices or segments
with
Hounsfield data values outside the expected values associated with the
fiducial key [810],
followed by the collecting of the remaining points [812]. If the data is empty
[814], the CT
value threshold is adjusted [816], the original data restored [818], and the
processing of scan
slices continues [810]. Otherwise, with the existing data a center of mass is
calculated [820],
as are the X, Y, and Z axes [822]. If the center of mass is not at the X, Y, Z
cross point
[824], then the user is notified [826] and the process ended [828]. If the
center of mass is at
the X, Y, Z cross point [824], then the pattern of the fiducial is compared to
the data [836],
and if the cumulative error is larger than the maximum allowed error [838] the
user is
notified [840] and the process is ended [842]. If the cumulative error is not
larger than the
maximum allowed error [838], then the coordinate system is defined at the XYZ
cross-point
[844] and the CT profile is updated for HU units [846]. This process of Figure
8A and
Figure 8B is repeated for each of pattern segments 720 that is to be employed
in determining
the spatial distortion of the surgical site. The information on the location
and orientation of
each of pattern segments 720 is then used as input to the method described
relating to Figure
8C.
[00093] Turning now to Figure 8C, image information is obtained from
camera [848]
and it is determined whether any particular segment 720 of multi-element
fiducial pattern
710 on the patient body is present in image information [850]. If no
particular pattern
segment 720 is present in the image information, then the user is queried as
to whether the
process should continue [852]. If not, then the process is ended [854]. If the
process is to
continue, the user is notified that no particular pattern segment 720 was
found in the image
information [856] and the process returns to obtaining image information from
camera [848].
If one of particular segments 720 is present in the image information at step
[850], then, other
ones of pattern segments 720 employed are identified and the three-dimensional
location and
orientation of all segments 720 employed are determined based on image
information [858].
The three-dimensional location and orientation of pattern segments 720
employed based on
the image information is compared with the three dimensional location and
orientation of the
same pattern segment as based on scan data [860]. Based on this comparison the
spatial
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distortion of the surgical site is determined [862]. In order to monitor such
distortions in real
time, the process may be looped back to obtain image information from camera
[848]. A
suitable query point [864] may be included to allow the user to terminate at
[866]. Detailed
methods for determining orientations and locations of predetermined shapes or
marked
tracking markers from image data are known to practitioners of the art and
will not be dwelt
upon here.
[00094] By the above method the software of the controller, for
example computer 210
of Figure 2, is capable of recognizing multi-element fiducial pattern 710 and
calculating a
model of the surgical site based on the identity of multi-element fiducial
pattern 710 and its
changes in shape based on observation data received from multi-element
fiducial pattern 710.
This allows the calculation in real time of the locations and orientations of
anatomical
features in the proximity of multi-element fiducial pattern 710.
[00095] In a further embodiment shown in Figures 9A and 9B, multi-
element fiducial
pattern 910 is deposited in a radio opaque ink in a spatially arbitrary
arrangement of elements
920 on the patient proximate patient skin at a surgical site. Figure 9A shows
pattern 910 as-
deposited and Figure 9B shows that pattern now changed to pattern 910' due to
variation of
the surgical site. The deposition of pattern 910 may be directly on the skin
or on a suitable
surgical incise film applied over the surgical site. Individual element 920
may be a single
point, or alternatively a small formless or defined shape. More generally,
individual element
920 may be a larger area, but having a locatable two-dimensional center-of-
mass. Individual
elements 920 of pattern 910 are not required to be individually directly
identifiable or unique
and may be placed in a non-predetermined spatial arrangement. The position of
each
individual element 920 may be determined directly from the three-dimensional
scan data of
the surgical site and this may be done in the coordinate system of the scan
data. The surgical
site and at least a portion of multi-element fiducial pattern 910 may be
imaged by tracker
930. The resulting image information may be supplied to a suitable controller,
for example
processor 214 and memory 217 of computer 210 of Figure 2. Such controller is
suitably
configured to determine a correspondence between the arrangement of a small
number of the
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individual elements in the image information and the corresponding individual
elements in
the scan data. In the present specification we refer to such a small number of
elements as a
"constellation of elements". Figures 9A and 9B show two constellations 940 and
950 of
individual elements. A constellation of elements with a minimum of three
points uniquely
identifies the particular constellation with the corresponding points in the
scan data.
Although it is possible that some constellations of points may become arranged
such that
they cannot be uniquely identified, for example if lying in a substantially
straight line, a large
number of points produced in a suitably random pattern should always allow a
suitable
choice of constellations to provide a sufficient number of correspondences,
thereby allowing
the identification of the position of any of elements 920. As the surgical
site changes,
constellations 940 and 950 may be repositioned and reoriented with repect to
each other, but
the local changes in their close vicinities are small. This allows individual
constellations 940
and 950 to remain uniquely identifiable.
[00096] Figures 9C and 9D illustrate a similar use of constellations,
wherein skin 912
of the surgical site receives transfer member 902, for example incise film or
transfer tape,
which bear elements 922. Elements 922, in addition to having radio-opaque
qualities, also
are visible to tracker 932 so that the location of elements 922, and their
corresponding
constellations 942 and 952, may be apparent on scans and image data. Certain
ones of
elements 922 form constellation 942, while other form constellation 952, which
during the
course of surgery may alter position as shown in Figure 9D with regards to
skin 912'.
[00097] Once a correspondence has been determined between
constellations of
elements in the image and the three dimensional element positions from the
scan data, then
the position and orientation of the tracker with respect to the surgical site
may be calculated
in the same way as with an arrangement of fiducial markers as described in the
previous
embodiments. The position and orientation of areas of the surgical site and
any other
implements with any other type of tracking markers may also be determined and
displayed in
the same way as in the earlier embodiments.
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[00098] As described with respect to another ink-based embodiments
above, the radio-
opaque ink may be, for example without limitation, the heavy metal based ink
described in
Falahee. A suitable ink may, without limitation, include barium heavy metal. A
suitable ink
composition for both x-ray tomography and nuclear magnetic resonance imaging
diagnostic
purposes is disclosed in Nambu. As disclosed in Nambu, the skin marker
composition that
may be employed in the disclosed embodiments may be comprised of a radioopaque
material
for x-ray diagnostic purposes and/or a non-magnetic hydrogel for magnetic
resonance
imaging purposes.
[00099] A further aspect of the present invention involves an
embodiment having an
automatic registration method for tracking surgical activity using a multi-
element fiducial
pattern 910, as shown in the flow chart diagram of Fig. 10. The method
comprises
depositing [1010] multi-element fiducial pattern 910 in a radio opaque ink in
an arbitrary
arrangement of elements 920 on the patient skin proximate surgical site 900;
obtaining
[1020] scan data about surgcal site 900; transferring [1030] image information
about surgical
site 900 from tracker 930; identifying [1040] within the image information
constellations
940, 950 of elements 920; identifying [1050] constellations 940, 950 of
elements 920 in the
scan data; deriving [1060] a three-dimensional transformation matrix to relate
multi-element
fiducial pattern 910 to a coordinate system of surgical site 900 based on the
position and
orientation of the constellation of elements 940, 950 in the scan data and the
position and
orientation of the constellation of elements 940, 950 in the image
information; and
determining [1070] the position and orientation of tracker 930 with respect to
surgical site
900. The depositing of the radio-opaque ink may comprise, in one embodiment
directly
applying such ink with or without the aid of a stencil (no shown), or in
alternative
embodiments applying a surgical incise film to the skin over surgical site 900
and then
depositing the radio-opaque ink on the surgical incise film.
[000100] If the surgical site is comparatively rigid, one constellation
of elements should
suffice for the disclosed method. If the surgical site is comparatively less
rigid, more than
one constellation of elements may be employed for enhancing the disclosed
method.
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[000101] With the position and orientation of the tracker now known in
the coordinate
system of the surgical site, the resulting virtual construct may then be used
by surgical
procedure planning software for virtual modeling of the contemplated
procedure. It may
alternatively be used to track changes in the surgical site as described in
one of foregoing
embodiments relating to real time tracking. It may also be used to track
surgical
instrumentation suitably marked with tracking markers or other three-
dimensionally
trackable markings that may be identified by the controller based on the image
information of
the surgical site obtained from tracker 930.
[000102] An advantage of these radio opaque ink embodiments involves
avoiding any
pre-manufactured markers to employ the apparatus and methods of the disclosed
invention,
as long as the instruments to be tracked are suitable marked for determining
their three-
dimensional position and orientation.
38
