U.S. patent application number 17/562051 was filed with the patent office on 2022-04-21 for weight-based registration of location sensors.
The applicant listed for this patent is Auris Health, Inc.. Invention is credited to Yuriy Malinin, Hedyeh Rafii-Tari, Subashini Srinivasan, Ritwik Ummalaneni, Menglong Ye.
Application Number | 20220117677 17/562051 |
Document ID | / |
Family ID | 1000006054331 |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220117677 |
Kind Code |
A1 |
Rafii-Tari; Hedyeh ; et
al. |
April 21, 2022 |
WEIGHT-BASED REGISTRATION OF LOCATION SENSORS
Abstract
Provided are systems and methods for weight-based registration
of location sensors. In one aspect, a system includes an instrument
and a processor configured to provide a first set of commands to
drive the instrument along a first branch of the luminal network,
the first branch being outside a path to a target within a model.
The processor is also configured to track a set of one or more
registration parameters during the driving of the instrument along
the first branch and determine that the set of registration
parameters satisfy a registration criterion. The processor is
further configured to determine a registration between a location
sensor coordinate system and a model coordinate system based on
location data received from a set of location sensors during the
driving of the instrument along the first branch and a second
branch.
Inventors: |
Rafii-Tari; Hedyeh;
(Mountain View, CA) ; Ye; Menglong; (Mountain
View, CA) ; Ummalaneni; Ritwik; (San Mateo, CA)
; Srinivasan; Subashini; (San Carlos, CA) ;
Malinin; Yuriy; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Auris Health, Inc. |
Redwood City |
CA |
US |
|
|
Family ID: |
1000006054331 |
Appl. No.: |
17/562051 |
Filed: |
December 27, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
17003374 |
Aug 26, 2020 |
11207141 |
|
|
17562051 |
|
|
|
|
62894639 |
Aug 30, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2034/2072 20160201;
A61B 34/20 20160201; A61B 1/04 20130101; A61B 2034/105 20160201;
A61B 2034/2065 20160201; A61B 2034/302 20160201; A61B 2034/303
20160201 |
International
Class: |
A61B 34/20 20060101
A61B034/20 |
Claims
1. A method of determining a registration between a sensor
coordinate system and a model coordinate system, the method
comprising: generating a set of sensor location points in the
sensor coordinate system based on location data generated by
location sensors of an instrument, the location data indicative of
a position of a distal end of the instrument in the sensor
coordinate system; determining a set of model location points in
the model coordinate system, determining an initial registration
between the sensor coordinate system and the model coordinate
system based on the set of sensor location points and the set of
model location points; determining a set of weight values
corresponding to the set of sensor location points; and determining
an updated registration between the sensor coordinate system and
the model coordinate system based on the set of sensor location
points, the set of model location points, and the set of weight
values.
2. The method of claim 1, wherein: the model comprises a skeleton
defined by midpoints along lumens of the luminal network, the
method further comprises: transforming the sensor location points
from the sensor coordinate system to the model coordinate system
using the initial registration; and determining a distance between
each of the transformed sensor location points in the model
coordinate system and the skeleton, and the determination of the
weight values is further based on distances between the transformed
sensor location points and the skeleton.
3. The method of claim 2, wherein the set of weight values are
binary.
4. The method of claim 3, further comprising: comparing each
distance between each of the transformed sensor location points and
the skeleton to a distance threshold, and assigning each of the
transformed sensor location points on of the binary weight values
based on the comparison.
5. The method of claim 1, wherein: the model further comprises
diameter values for the lumens of the luminal network, and the
determination of the weight values is further based on the diameter
values of the lumens.
6. The method of claim 1, wherein: the instrument further comprises
a camera configured to capture images of an interior of the luminal
network, the method further comprises, for each of the sensor
location points, determining a distance between the distal end of
the instrument and a centerline of a lumen in which the distal end
of the instrument is located based on the captured images, and the
determination of the weight values for the sensor location points
is further based on distances between the distal end of the
instrument and corresponding centerlines of the lumens.
7. The method of claim 1, wherein: the model comprises a skeleton
defined by midpoints along lumens of the luminal network, the
method further comprises: sorting the sensor location points based
on a distance from each of the sensor location points to the
skeleton for a given lumen, and assigning the weights to the sensor
location points based on the sorted sensor location points.
8. The method of claim 7, wherein the sorting of the sensor
location points includes: sorting a defined percentage of the
sensor location points having a smallest distance into a first
group and remaining sensor location points into a second group.
9. The method of claim 8, wherein: the set of weight values are
binary, and the method further comprises: assigning the sensor
location points in the first group a weight of 1, and assigning the
sensor location point in the second group a weight of 0.
10. The method of claim 1, wherein: the set of weight values are
binary, a subset of the set of sensor location points correspond to
the distal end of the instrument located in a second generation
lumen, and the subset of the set of model location points are
assigned a value of 1.
11. The method of claim 1, wherein: the method further comprises:
determining an error associated with the initial registration for a
first one the sensor location points; and in response to the error
being greater than a threshold error, locking the initial
registration.
12. The method of claim 11, wherein the determining of the updated
registration is further the first sensor location point in response
to the error being less than or equal to the threshold error.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a division of U.S. application Ser. No.
17/003,374, filed Aug. 26, 2020, which claims the benefit of U.S.
Provisional Application No. 62/894,639, filed Aug. 30, 2019, each
of which is hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The systems and methods disclosed herein are directed to
systems and methods for registration of location sensors, and more
particularly to weighting the registration of a location sensor
coordinate system to another coordinate system.
BACKGROUND
[0003] Medical procedures such as endoscopy (e.g., bronchoscopy)
may involve the insertion of a medical tool into a patient's
luminal network (e.g., airways) for diagnostic and/or therapeutic
purposes. Surgical robotic systems may be used to control the
insertion and/or manipulation of the medical tool during a medical
procedure. The surgical robotic system may comprise at least one
robotic arm including a manipulator assembly which may be used to
control the positioning of the medical tool prior to and during the
medical procedure. The surgical robotic system may further comprise
location sensor(s) configured to generate location data indicative
of a position of the distal end of the medical tool with respect to
a location sensor coordinate system.
[0004] The surgical robotic system may further utilize a model of a
luminal network of a patient, which may be defined with respect to
a model coordinate system. The location sensor coordinate system
may not be registered to the model coordinate system, and thus the
system may perform a process to achieve registration between the
location sensor coordinate system and the model coordinate system
such that location data received from the location sensor(s) can be
used to determine the position of the distal end of the medical
tool with respect to the model.
SUMMARY
[0005] The systems, methods and devices of this disclosure each
have several innovative aspects, no single one of which is solely
responsible for the desirable attributes disclosed herein.
[0006] In one aspect, there is provided a system, comprising: an
instrument comprising a set of one or more location sensors, the
set of location sensors configured to generate location data
indicative of a position of the set of location sensors in a
location sensor coordinate system; a set of instrument manipulators
configured to control movement of the distal end of the instrument;
a set of processors; and at least one computer-readable memory in
communication with the set of processors and having stored thereon
a model of a luminal network of a patient, the model comprising a
target within a model coordinate system and a path to the target.
The memory may further have stored thereon computer-executable
instructions to cause the set of processors to: provide a first set
of commands to the set of instrument manipulators to drive the
instrument along a first branch of the luminal network, the first
branch being outside the path to the target, track a set of one or
more registration parameters during the driving of the instrument
along the first branch; determine that the set of registration
parameters satisfy a registration criterion, provide a second set
of commands to the set of instrument manipulators to return the
instrument back to the path and to drive the instrument along a
second branch, the second branch being part of the path to the
target; and determine a registration between the location sensor
coordinate system and the model coordinate system based on the
location data received from the set of location sensors during the
driving of the instrument along the first branch and the second
branch.
[0007] In another aspect, there is provided a non-transitory
computer readable storage medium having stored thereon instructions
that, when executed, cause at least one computing device to:
provide a first set of commands to a set of instrument manipulators
to drive an instrument along a first branch of a luminal network,
the instrument comprising a set of one or more location sensors,
the set of location sensors configured to generate location data
indicative of a position of the set of location sensors in a
location sensor coordinate system, the set of instrument
manipulators configured to control movement of the distal end of
the instrument, a memory having stored thereon a model of a luminal
network of a patient, the model comprising a target within a model
coordinate system and a path to the target, the first branch being
outside the path to the target; track a set of one or more
registration parameters during the driving of the instrument along
the first branch; determine that the set of registration parameters
satisfy a registration criterion; provide a second set of commands
to the set of instrument manipulators to return the instrument back
to the path and to drive the instrument along a second branch, the
second branch being part of the path to the target; and determine a
registration between the location sensor coordinate system and the
model coordinate system based on the location data received from
the set of location sensors during the driving of the instrument
along the first branch and the second branch.
[0008] In yet another aspect, there is provided a method of
registering a set of one or more location sensors, comprising:
providing a first set of commands to a set of instrument
manipulators to drive an instrument along a first branch of a
luminal network, the instrument comprising the set of location
sensors, the set of location sensors configured to generate
location data indicative of a position of the set of location
sensors in a location sensor coordinate system, the set of
instrument manipulators configured to control movement of the
distal end of the instrument, a memory having stored thereon a
model of a luminal network of a patient, the model comprising a
target within a model coordinate system and a path to the target,
the first branch being outside the path to the target; tracking a
set of one or more registration parameters during the driving of
the instrument along the first branch; determining that the set of
registration parameters satisfy a registration criterion, providing
a second set of commands to the set of instrument manipulators to
return the instrument back to the path and to drive the instrument
along a second branch, the second branch being part of the path to
the target; and determining a registration between the location
sensor coordinate system and the model coordinate system based on
the location data received from the set of location sensors during
the driving of the instrument along the first branch and the second
branch.
[0009] In still yet another aspect, there is provided a system
comprising a set of one or more processors and at least one
computer-readable memory in communication with the set of
processors and having stored thereon a model of a luminal network
of a patient, the model comprising a target within a model
coordinate system and a path to the target, the memory further
having stored thereon computer-executable instructions to cause the
set of processors to: provide instructions to display the luminal
network via a display device, receive an indication of a location
of a target within the model coordinate system; identify a first
branch and a second branch in the luminal network, the first branch
being outside the path to the target, the second branch being a
part of the path to the target, generate a set of instructions for
driving the distal end of the instrument along the first branch,
back to the path from the first branch, and along the second
branch, wherein location data received from a set of one or more
locations sensors during the driving of the instrument according to
the instructions facilitates a registration between the a location
coordinate system of the location data and the model coordinate
system; and determine a registration criterion for one or more
registration parameters tracked during the driving of the
instrument along the first branch.
[0010] In yet another aspect there is provided a non-transitory
computer readable storage medium having stored thereon instructions
that, when executed, cause at least one computing device to:
provide instructions to display a luminal network via a display
device, the luminal network being stored on the non-transitory
computer readable storage medium, and the model comprising a target
within a model coordinate system and a path to the target; receive
an indication of a location of a target within the model coordinate
system; identify a first branch and a second branch in the luminal
network, the first branch being outside the path to the target, the
second branch being a part of the path to the target; generate a
set of instructions for driving the distal end of the instrument
along the first branch, back to the path from the first branch, and
along the second branch, wherein location data received from a set
of one or more locations sensors during the driving of the
instrument according to the instructions facilitates a registration
between the a location coordinate system of the location data and
the model coordinate system; and determine a registration criterion
for one or more registration parameters tracked during the driving
of the instrument along the first branch.
[0011] In another aspect, there is provided a method of
pre-operative planning, comprising: providing instructions to
display a luminal network via a display device, the luminal network
being stored on the non-transitory computer readable storage
medium, and the model comprising a target within a model coordinate
system and a path to the target; receiving an indication of a
location of a target within the model coordinate system;
identifying a first branch and a second branch in the luminal
network, the first branch being outside the path to the target, the
second branch being a part of the path to the target; generating a
set of instructions for driving the distal end of the instrument
along the first branch, back to the path from the first branch, and
along the second branch, wherein location data received from a set
of one or more locations sensors during the driving of the
instrument according to the instructions facilitates a registration
between the a location coordinate system of the location data and
the model coordinate system; and determining a registration
criterion for one or more registration parameters tracked during
the driving of the instrument along the first branch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The disclosed aspects will hereinafter be described in
conjunction with the appended drawings, provided to illustrate and
not to limit the disclosed aspects, wherein like designations
denote like elements.
[0013] FIG. 1 illustrates an embodiment of a cart-based robotic
system arranged for diagnostic and/or therapeutic bronchoscopy
procedure(s).
[0014] FIG. 2 depicts further aspects of the robotic system of FIG.
1.
[0015] FIG. 3 illustrates an embodiment of the robotic system of
FIG. 1 arranged for ureteroscopy.
[0016] FIG. 4 illustrates an embodiment of the robotic system of
FIG. 1 arranged for a vascular procedure.
[0017] FIG. 5 illustrates an embodiment of a table-based robotic
system arranged for a bronchoscopy procedure.
[0018] FIG. 6 provides an alternative view of the robotic system of
FIG. 5.
[0019] FIG. 7 illustrates an example system configured to stow
robotic arm(s).
[0020] FIG. 8 illustrates an embodiment of a table-based robotic
system configured for a ureteroscopy procedure.
[0021] FIG. 9 illustrates an embodiment of a table-based robotic
system configured for a laparoscopic procedure.
[0022] FIG. 10 illustrates an embodiment of the table-based robotic
system of FIGS. 5-9 with pitch or tilt adjustment.
[0023] FIG. 11 provides a detailed illustration of the interface
between the table and the column of the table-based robotic system
of FIGS. 5-10.
[0024] FIG. 12 illustrates an exemplary instrument driver.
[0025] FIG. 13 illustrates an exemplary medical instrument with a
paired instrument driver.
[0026] FIG. 14 illustrates an alternative design for an instrument
driver and instrument where the axes of the drive units are
parallel to the axis of the elongated shaft of the instrument.
[0027] FIG. 15 depicts a block diagram illustrating a localization
system that estimates a location of one or more elements of the
robotic systems of FIGS. 1-10, such as the location of the
instrument of FIGS. 13 and 14, in accordance to an example
embodiment.
[0028] FIG. 16A illustrates an example operating environment
implementing one or more aspects of the disclosed navigation
systems and techniques.
[0029] FIG. 16B illustrates an example luminal network that can be
navigated in the operating environment of FIG. 16A.
[0030] FIG. 16C illustrates an example robotic arm of a robotic
system for guiding instrument movement in through the luminal
network of FIG. 16B.
[0031] FIG. 17 illustrates an example command console that can be
used, for example, as the command console in the example operating
environment.
[0032] FIG. 18 illustrates the distal end of an example instrument
having imaging and EM sensing capabilities as described herein, for
example, the instrument of FIGS. 16A-16C.
[0033] FIG. 19 illustrates an example luminal network in which
location sensor registration can be performed in accordance with
aspects of this disclosure.
[0034] FIG. 20A is a flowchart illustrating an example method
operable by a surgical robotic system, or component(s) thereof, for
contra-laterally registering a location sensor coordinate system in
accordance with aspects of this disclosure.
[0035] FIG. 20B is a flowchart illustrating an example method
operable by a surgical robotic system, or component(s) thereof, for
determining whether sufficient location data has been received to
facilitate contra-lateral registration in accordance with aspects
of this disclosure.
[0036] FIG. 21 is a diagram illustrating location data with respect
to a model of a luminal network in accordance with aspects of this
disclosure.
[0037] FIG. 22 is a diagram illustrating an example of registration
of location data without preforming a contra-lateral registration
process in accordance with aspects of this disclosure.
[0038] FIG. 23 is a flowchart illustrating an example method
operable by a surgical robotic system, or component(s) thereof, for
pre-operative planning in accordance with aspects of this
disclosure.
[0039] FIG. 24 is flowchart illustrating an example method for
determining a registration between the sensor coordinate system and
the model coordinate system.
[0040] FIG. 25 illustrates an example in which sensor location
points and model location points are overlaid on the model in the
model coordinate system.
[0041] FIG. 26 illustrates one example for determining weights
proportional to distance.
[0042] FIG. 27 illustrates another example for determining binary
weights based on distance.
[0043] FIG. 28 illustrates yet another example for determining
binary weights based on distance.
DETAILED DESCRIPTION
1. Overview
[0044] Aspects of the present disclosure may be integrated into a
robotically-enabled medical system capable of performing a variety
of medical procedures, including both minimally invasive, such as
laparoscopy, and non-invasive, such as endoscopy, procedures. Among
endoscopy procedures, the system may be capable of performing
bronchoscopy, ureteroscopy, gastroscopy, etc.
[0045] In addition to performing the breadth of procedures, the
system may provide additional benefits, such as enhanced imaging
and guidance to assist the physician. Additionally, the system may
provide the physician with the ability to perform the procedure
from an ergonomic position without the need for awkward arm motions
and positions. Still further, the system may provide the physician
with the ability to perform the procedure with improved ease of use
such that one or more of the instruments of the system can be
controlled by a single user.
[0046] Various embodiments will be described below in conjunction
with the drawings for purposes of illustration. It should be
appreciated that many other implementations of the disclosed
concepts are possible, and various advantages can be achieved with
the disclosed implementations. Headings are included herein for
reference and to aid in locating various sections. These headings
are not intended to limit the scope of the concepts described with
respect thereto. Such concepts may have applicability throughout
the entire specification.
A. Robotic System--Cart.
[0047] The robotically-enabled medical system may be configured in
a variety of ways depending on the particular procedure. FIG. 1
illustrates an embodiment of a cart-based robotically-enabled
system 10 arranged for a diagnostic and/or therapeutic bronchoscopy
procedure. During a bronchoscopy, the system 10 may comprise a cart
11 having one or more robotic arms 12 to deliver a medical
instrument, such as a steerable endoscope 13, which may be a
procedure-specific bronchoscope for bronchoscopy, to a natural
orifice access point (i.e., the mouth of the patient positioned on
a table in the present example) to deliver diagnostic and/or
therapeutic tools. As shown, the cart 11 may be positioned
proximate to the patient's upper torso in order to provide access
to the access point. Similarly, the robotic arms 12 may be actuated
to position the bronchoscope relative to the access point. The
arrangement in FIG. 1 may also be utilized when performing a
gastro-intestinal (GI) procedure with a gastroscope, a specialized
endoscope for GI procedures. FIG. 2 depicts an example embodiment
of the cart in greater detail.
[0048] With continued reference to FIG. 1, once the cart 11 is
properly positioned, the robotic arms 12 may insert the steerable
endoscope 13 into the patient robotically, manually, or a
combination thereof. As shown, the steerable endoscope 13 may
comprise at least two telescoping parts, such as an inner leader
portion and an outer sheath portion, each portion coupled to a
separate instrument driver from the set of instrument drivers 28,
each instrument driver coupled to the distal end of an individual
robotic arm. This linear arrangement of the instrument drivers 28,
which facilitates coaxially aligning the leader portion with the
sheath portion, creates a "virtual rail" 29 that may be
repositioned in space by manipulating the one or more robotic arms
12 into different angles and/or positions. The virtual rails
described herein are depicted in the Figures using dashed lines,
and accordingly the dashed lines do not depict any physical
structure of the system. Translation of the instrument drivers 28
along the virtual rail 29 telescopes the inner leader portion
relative to the outer sheath portion or advances or retracts the
endoscope 13 from the patient. The angle of the virtual rail 29 may
be adjusted, translated, and pivoted based on clinical application
or physician preference. For example, in bronchoscopy, the angle
and position of the virtual rail 29 as shown represents a
compromise between providing physician access to the endoscope 13
while minimizing friction that results from bending the endoscope
13 into the patient's mouth.
[0049] The endoscope 13 may be directed down the patient's trachea
and lungs after insertion using precise commands from the robotic
system until reaching the target destination or operative site. In
order to enhance navigation through the patient's lung network
and/or reach the desired target, the endoscope 13 may be
manipulated to telescopically extend the inner leader portion from
the outer sheath portion to obtain enhanced articulation and
greater bend radius. The use of separate instrument drivers 28 also
allows the leader portion and sheath portion to be driven
independent of each other.
[0050] For example, the endoscope 13 may be directed to deliver a
biopsy needle to a target, such as, for example, a lesion or nodule
within the lungs of a patient. The needle may be deployed down a
working channel that runs the length of the endoscope to obtain a
tissue sample to be analyzed by a pathologist. Depending on the
pathology results, additional tools may be deployed down the
working channel of the endoscope for additional biopsies. After
identifying a nodule to be malignant, the endoscope 13 may
endoscopically deliver tools to resect the potentially cancerous
tissue. In some instances, diagnostic and therapeutic treatments
may need to be delivered in separate procedures. In those
circumstances, the endoscope 13 may also be used to deliver a
fiducial to "mark" the location of the target nodule as well. In
other instances, diagnostic and therapeutic treatments may be
delivered during the same procedure.
[0051] The system 10 may also include a movable tower 30, which may
be connected via support cables to the cart 11 to provide support
for controls, electronics, fluidics, optics, sensors, and/or power
to the cart 11. Placing such functionality in the tower 30 allows
for a smaller form factor cart 11 that may be more easily adjusted
and/or re-positioned by an operating physician and his/her staff.
Additionally, the division of functionality between the cart/table
and the support tower 30 reduces operating room clutter and
facilitates improving clinical workflow. While the cart 11 may be
positioned close to the patient, the tower 30 may be stowed in a
remote location to stay out of the way during a procedure.
[0052] In support of the robotic systems described above, the tower
30 may include component(s) of a computer-based control system that
stores computer program instructions, for example, within a
non-transitory computer-readable storage medium such as a
persistent magnetic storage drive, solid state drive, etc. The
execution of those instructions, whether the execution occurs in
the tower 30 or the cart 11, may control the entire system or
sub-system(s) thereof. For example, when executed by a processor of
the computer system, the instructions may cause the components of
the robotics system to actuate the relevant carriages and arm
mounts, actuate the robotics arms, and control the medical
instruments. For example, in response to receiving the control
signal, the motors in the joints of the robotics arms may position
the arms into a certain posture.
[0053] The tower 30 may also include a pump, flow meter, valve
control, and/or fluid access in order to provide controlled
irrigation and aspiration capabilities to system that may be
deployed through the endoscope 13. These components may also be
controlled using the computer system of tower 30. In some
embodiments, irrigation and aspiration capabilities may be
delivered directly to the endoscope 13 through separate
cable(s).
[0054] The tower 30 may include a voltage and surge protector
designed to provide filtered and protected electrical power to the
cart 11, thereby avoiding placement of a power transformer and
other auxiliary power components in the cart 11, resulting in a
smaller, more moveable cart 11.
[0055] The tower 30 may also include support equipment for the
sensors deployed throughout the robotic system 10. For example, the
tower 30 may include opto-electronics equipment for detecting,
receiving, and processing data received from the optical sensors or
cameras throughout the robotic system 10. In combination with the
control system, such opto-electronics equipment may be used to
generate real-time images for display in any number of consoles
deployed throughout the system, including in the tower 30.
Similarly, the tower 30 may also include an electronic subsystem
for receiving and processing signals received from deployed
electromagnetic (EM) sensors. The tower 30 may also be used to
house and position an EM field generator for detection by EM
sensors in or on the medical instrument.
[0056] The tower 30 may also include a console 31 in addition to
other consoles available in the rest of the system, e.g., console
mounted on top of the cart. The console 31 may include a user
interface and a display screen, such as a touchscreen, for the
physician operator. Consoles in system 10 are generally designed to
provide both robotic controls as well as pre-operative and
real-time information of the procedure, such as navigational and
localization information of the endoscope 13. When the console 31
is not the only console available to the physician, it may be used
by a second operator, such as a nurse, to monitor the health or
vitals of the patient and the operation of system, as well as
provide procedure-specific data, such as navigational and
localization information.
[0057] The tower 30 may be coupled to the cart 11 and endoscope 13
through one or more cables or connections (not shown). In some
embodiments, the support functionality from the tower 30 may be
provided through a single cable to the cart 11, simplifying and
de-cluttering the operating room. In other embodiments, specific
functionality may be coupled in separate cabling and connections.
For example, while power may be provided through a single power
cable to the cart, the support for controls, optics, fluidics,
and/or navigation may be provided through a separate cable.
[0058] FIG. 2 provides a detailed illustration of an embodiment of
the cart from the cart-based robotically-enabled system shown in
FIG. 1. The cart 11 generally includes an elongated support
structure 14 (often referred to as a "column"), a cart base 15, and
a console 16 at the top of the column 14. The column 14 may include
one or more carriages, such as a carriage 17 (alternatively "arm
support") for supporting the deployment of one or more robotic arms
12 (three shown in FIG. 2). The carriage 17 may include
individually configurable arm mounts that rotate along a
perpendicular axis to adjust the base of the robotic arms 12 for
better positioning relative to the patient. The carriage 17 also
includes a carriage interface 19 that allows the carriage 17 to
vertically translate along the column 14.
[0059] The carriage interface 19 is connected to the column 14
through slots, such as slot 20, that are positioned on opposite
sides of the column 14 to guide the vertical translation of the
carriage 17. The slot 20 contains a vertical translation interface
to position and hold the carriage at various vertical heights
relative to the cart base 15. Vertical translation of the carriage
17 allows the cart 11 to adjust the reach of the robotic arms 12 to
meet a variety of table heights, patient sizes, and physician
preferences. Similarly, the individually configurable arm mounts on
the carriage 17 allow the robotic arm base 21 of robotic arms 12 to
be angled in a variety of configurations.
[0060] In some embodiments, the slot 20 may be supplemented with
slot covers that are flush and parallel to the slot surface to
prevent dirt and fluid ingress into the internal chambers of the
column 14 and the vertical translation interface as the carriage 17
vertically translates. The slot covers may be deployed through
pairs of spring spools positioned near the vertical top and bottom
of the slot 20. The covers are coiled within the spools until
deployed to extend and retract from their coiled state as the
carriage 17 vertically translates up and down. The spring-loading
of the spools provides force to retract the cover into a spool when
carriage 17 translates towards the spool, while also maintaining a
tight seal when the carriage 17 translates away from the spool. The
covers may be connected to the carriage 17 using, for example,
brackets in the carriage interface 19 to ensure proper extension
and retraction of the cover as the carriage 17 translates.
[0061] The column 14 may internally comprise mechanisms, such as
gears and motors, that are designed to use a vertically aligned
lead screw to translate the carriage 17 in a mechanized fashion in
response to control signals generated in response to user inputs,
e.g., inputs from the console 16.
[0062] The robotic arms 12 may generally comprise robotic arm bases
21 and end effectors 22, separated by a series of linkages 23 that
are connected by a series of joints 24, each joint comprising an
independent actuator, each actuator comprising an independently
controllable motor. Each independently controllable joint
represents an independent degree of freedom available to the
robotic arm. Each of the arms 12 have seven joints, and thus
provide seven degrees of freedom. A multitude of joints result in a
multitude of degrees of freedom, allowing for "redundant" degrees
of freedom. Redundant degrees of freedom allow the robotic arms 12
to position their respective end effectors 22 at a specific
position, orientation, and trajectory in space using different
linkage positions and joint angles. This allows for the system to
position and direct a medical instrument from a desired point in
space while allowing the physician to move the arm joints into a
clinically advantageous position away from the patient to create
greater access, while avoiding arm collisions.
[0063] The cart base 15 balances the weight of the column 14,
carriage 17, and arms 12 over the floor. Accordingly, the cart base
15 houses heavier components, such as electronics, motors, power
supply, as well as components that either enable movement and/or
immobilize the cart. For example, the cart base 15 includes
rollable wheel-shaped casters 25 that allow for the cart to easily
move around the room prior to a procedure. After reaching the
appropriate position, the casters 25 may be immobilized using wheel
locks to hold the cart 11 in place during the procedure.
[0064] Positioned at the vertical end of column 14, the console 16
allows for both a user interface for receiving user input and a
display screen (or a dual-purpose device such as, for example, a
touchscreen 26) to provide the physician user with both
pre-operative and intra-operative data. Potential pre-operative
data on the touchscreen 26 may include pre-operative plans,
navigation and mapping data derived from pre-operative computerized
tomography (CT) scans, and/or notes from pre-operative patient
interviews. Intra-operative data on display may include optical
information provided from the tool, sensor and coordinate
information from sensors, as well as vital patient statistics, such
as respiration, heart rate, and/or pulse. The console 16 may be
positioned and tilted to allow a physician to access the console
from the side of the column 14 opposite carriage 17. From this
position, the physician may view the console 16, robotic arms 12,
and patient while operating the console 16 from behind the cart 11.
As shown, the console 16 also includes a handle 27 to assist with
maneuvering and stabilizing cart 11.
[0065] FIG. 3 illustrates an embodiment of a robotically-enabled
system 10 arranged for ureteroscopy. In a ureteroscopic procedure,
the cart 11 may be positioned to deliver a ureteroscope 32, a
procedure-specific endoscope designed to traverse a patient's
urethra and ureter, to the lower abdominal area of the patient. In
a ureteroscopy, it may be desirable for the ureteroscope 32 to be
directly aligned with the patient's urethra to reduce friction and
forces on the sensitive anatomy in the area. As shown, the cart 11
may be aligned at the foot of the table to allow the robotic arms
12 to position the ureteroscope 32 for direct linear access to the
patient's urethra. From the foot of the table, the robotic arms 12
may insert the ureteroscope 32 along the virtual rail 33 directly
into the patient's lower abdomen through the urethra.
[0066] After insertion into the urethra, using similar control
techniques as in bronchoscopy, the ureteroscope 32 may be navigated
into the bladder, ureters, and/or kidneys for diagnostic and/or
therapeutic applications. For example, the ureteroscope 32 may be
directed into the ureter and kidneys to break up kidney stone build
up using laser or ultrasonic lithotripsy device deployed down the
working channel of the ureteroscope 32. After lithotripsy is
complete, the resulting stone fragments may be removed using
baskets deployed down the ureteroscope 32.
[0067] FIG. 4 illustrates an embodiment of a robotically-enabled
system similarly arranged for a vascular procedure. In a vascular
procedure, the system 10 may be configured such the cart 11 may
deliver a medical instrument 34, such as a steerable catheter, to
an access point in the femoral artery in the patient's leg. The
femoral artery presents both a larger diameter for navigation as
well as relatively less circuitous and tortuous path to the
patient's heart, which simplifies navigation. As in a ureteroscopic
procedure, the cart 11 may be positioned towards the patient's legs
and lower abdomen to allow the robotic arms 12 to provide a virtual
rail 35 with direct linear access to the femoral artery access
point in the patient's thigh/hip region. After insertion into the
artery, the medical instrument 34 may be directed and inserted by
translating the instrument drivers 28. Alternatively, the cart may
be positioned around the patient's upper abdomen in order to reach
alternative vascular access points, such as, for example, the
carotid and brachial arteries near the shoulder and wrist.
B. Robotic System--Table.
[0068] Embodiments of the robotically-enabled medical system may
also incorporate the patient's table. Incorporation of the table
reduces the amount of capital equipment within the operating room
by removing the cart, which allows greater access to the patient.
FIG. 5 illustrates an embodiment of such a robotically-enabled
system arranged for a bronchoscopy procedure. System 36 includes a
support structure or column 37 for supporting platform 38 (shown as
a "table" or "bed") over the floor. Much like in the cart-based
systems, the end effectors of the robotic arms 39 of the system 36
comprise instrument drivers 42 that are designed to manipulate an
elongated medical instrument, such as a bronchoscope 40 in FIG. 5,
through or along a virtual rail 41 formed from the linear alignment
of the instrument drivers 42. In practice, a C-arm for providing
fluoroscopic imaging may be positioned over the patient's upper
abdominal area by placing the emitter and detector around table
38.
[0069] FIG. 6 provides an alternative view of the system 36 without
the patient and medical instrument for discussion purposes. As
shown, the column 37 may include one or more carriages 43 shown as
ring-shaped in the system 36, from which the one or more robotic
arms 39 may be based. The carriages 43 may translate along a
vertical column interface 44 that runs the length of the column 37
to provide different vantage points from which the robotic arms 39
may be positioned to reach the patient. The carriage(s) 43 may
rotate around the column 37 using a mechanical motor positioned
within the column 37 to allow the robotic arms 39 to have access to
multiples sides of the table 38, such as, for example, both sides
of the patient. In embodiments with multiple carriages, the
carriages may be individually positioned on the column and may
translate and/or rotate independent of the other carriages. While
carriages 43 need not surround the column 37 or even be circular,
the ring-shape as shown facilitates rotation of the carriages 43
around the column 37 while maintaining structural balance. Rotation
and translation of the carriages 43 allows the system to align the
medical instruments, such as endoscopes and laparoscopes, into
different access points on the patient.
[0070] The arms 39 may be mounted on the carriages through a set of
arm mounts 45 comprising a series of joints that may individually
rotate and/or telescopically extend to provide additional
configurability to the robotic arms 39. Additionally, the arm
mounts 45 may be positioned on the carriages 43 such that, when the
carriages 43 are appropriately rotated, the arm mounts 45 may be
positioned on either the same side of table 38 (as shown in FIG.
6), on opposite sides of table 38 (as shown in FIG. 9), or on
adjacent sides of the table 38 (not shown).
[0071] The column 37 structurally provides support for the table
38, and a path for vertical translation of the carriages.
Internally, the column 37 may be equipped with lead screws for
guiding vertical translation of the carriages, and motors to
mechanize the translation of said carriages based the lead screws.
The column 37 may also convey power and control signals to the
carriage 43 and robotic arms 39 mounted thereon.
[0072] The table base 46 serves a similar function as the cart base
15 in cart 11 shown in FIG. 2, housing heavier components to
balance the table/bed 38, the column 37, the carriages 43, and the
robotic arms 39. The table base 46 may also incorporate rigid
casters to provide stability during procedures. Deployed from the
bottom of the table base 46, the casters may extend in opposite
directions on both sides of the base 46 and retract when the system
36 needs to be moved.
[0073] Continuing with FIG. 6, the system 36 may also include a
tower (not shown) that divides the functionality of system 36
between table and tower to reduce the form factor and bulk of the
table. As in earlier disclosed embodiments, the tower may provide a
variety of support functionalities to table, such as processing,
computing, and control capabilities, power, fluidics, and/or
optical and sensor processing. The tower may also be movable to be
positioned away from the patient to improve physician access and
de-clutter the operating room. Additionally, placing components in
the tower allows for more storage space in the table base for
potential stowage of the robotic arms. The tower may also include a
console that provides both a user interface for user input, such as
keyboard and/or pendant, as well as a display screen (or
touchscreen) for pre-operative and intra-operative information,
such as real-time imaging, navigation, and tracking
information.
[0074] In some embodiments, a table base may stow and store the
robotic arms when not in use. FIG. 7 illustrates a system 47 that
stows robotic arms in an embodiment of the table-based system. In
system 47, carriages 48 may be vertically translated into base 49
to stow robotic arms 50, arm mounts 51, and the carriages 48 within
the base 49. Base covers 52 may be translated and retracted open to
deploy the carriages 48, arm mounts 51, and arms 50 around column
53, and closed to stow to protect them when not in use. The base
covers 52 may be sealed with a membrane 54 along the edges of its
opening to prevent dirt and fluid ingress when closed.
[0075] FIG. 8 illustrates an embodiment of a robotically-enabled
table-based system configured for a ureteroscopy procedure. In a
ureteroscopy, the table 38 may include a swivel portion 55 for
positioning a patient off-angle from the column 37 and table base
46. The swivel portion 55 may rotate or pivot around a pivot point
(e.g., located below the patient's head) in order to position the
bottom portion of the swivel portion 55 away from the column 37.
For example, the pivoting of the swivel portion 55 allows a C-arm
(not shown) to be positioned over the patient's lower abdomen
without competing for space with the column (not shown) below table
38. By rotating the carriage 35 (not shown) around the column 37,
the robotic arms 39 may directly insert a ureteroscope 56 along a
virtual rail 57 into the patient's groin area to reach the urethra.
In a ureteroscopy, stirrups 58 may also be fixed to the swivel
portion 55 of the table 38 to support the position of the patient's
legs during the procedure and allow clear access to the patient's
groin area.
[0076] In a laparoscopic procedure, through small incision(s) in
the patient's abdominal wall, minimally invasive instruments
(elongated in shape to accommodate the size of the one or more
incisions) may be inserted into the patient's anatomy. After
inflation of the patient's abdominal cavity, the instruments, often
referred to as laparoscopes, may be directed to perform surgical
tasks, such as grasping, cutting, ablating, suturing, etc. FIG. 9
illustrates an embodiment of a robotically-enabled table-based
system configured for a laparoscopic procedure. As shown in FIG. 9,
the carriages 43 of the system 36 may be rotated and vertically
adjusted to position pairs of the robotic arms 39 on opposite sides
of the table 38, such that laparoscopes 59 may be positioned using
the arm mounts 45 to be passed through minimal incisions on both
sides of the patient to reach his/her abdominal cavity.
[0077] To accommodate laparoscopic procedures, the
robotically-enabled table system may also tilt the platform to a
desired angle. FIG. 10 illustrates an embodiment of the
robotically-enabled medical system with pitch or tilt adjustment.
As shown in FIG. 10, the system 36 may accommodate tilt of the
table 38 to position one portion of the table at a greater distance
from the floor than the other. Additionally, the arm mounts 45 may
rotate to match the tilt such that the arms 39 maintain the same
planar relationship with table 38. To accommodate steeper angles,
the column 37 may also include telescoping portions 60 that allow
vertical extension of column 37 to keep the table 38 from touching
the floor or colliding with base 46.
[0078] FIG. 11 provides a detailed illustration of the interface
between the table 38 and the column 37. Pitch rotation mechanism 61
may be configured to alter the pitch angle of the table 38 relative
to the column 37 in multiple degrees of freedom. The pitch rotation
mechanism 61 may be enabled by the positioning of orthogonal axes
1, 2 at the column-table interface, each axis actuated by a
separate motor 3, 4 responsive to an electrical pitch angle
command. Rotation along one screw 5 would enable tilt adjustments
in one axis 1, while rotation along the other screw 6 would enable
tilt adjustments along the other axis 2.
[0079] For example, pitch adjustments are particularly useful when
trying to position the table in a Trendelenburg position, i.e.,
position the patient's lower abdomen at a higher position from the
floor than the patient's lower abdomen, for lower abdominal
surgery. The Trendelenburg position causes the patient's internal
organs to slide towards his/her upper abdomen through the force of
gravity, clearing out the abdominal cavity for minimally invasive
tools to enter and perform lower abdominal surgical procedures,
such as laparoscopic prostatectomy.
C. Instrument Driver & Interface.
[0080] The end effectors of the system's robotic arms comprise (i)
an instrument driver (alternatively referred to as "instrument
drive mechanism" or "instrument device manipulator") that
incorporate electro-mechanical means for actuating the medical
instrument and (ii) a removable or detachable medical instrument
which may be devoid of any electro-mechanical components, such as
motors. This dichotomy may be driven by the need to sterilize
medical instruments used in medical procedures, and the inability
to adequately sterilize expensive capital equipment due to their
intricate mechanical assemblies and sensitive electronics.
Accordingly, the medical instruments may be designed to be
detached, removed, and interchanged from the instrument driver (and
thus the system) for individual sterilization or disposal by the
physician or the physician's staff. In contrast, the instrument
drivers need not be changed or sterilized, and may be draped for
protection.
[0081] FIG. 12 illustrates an example instrument driver. Positioned
at the distal end of a robotic arm, instrument driver 62 comprises
of one or more drive units 63 arranged with parallel axes to
provide controlled torque to a medical instrument via drive shafts
64. Each drive unit 63 comprises an individual drive shaft 64 for
interacting with the instrument, a gear head 65 for converting the
motor shaft rotation to a desired torque, a motor 66 for generating
the drive torque, an encoder 67 to measure the speed of the motor
shaft and provide feedback to the control circuitry, and control
circuitry 68 for receiving control signals and actuating the drive
unit. Each drive unit 63 being independent controlled and
motorized, the instrument driver 62 may provide multiple (four as
shown in FIG. 12) independent drive outputs to the medical
instrument. In operation, the control circuitry 68 would receive a
control signal, transmit a motor signal to the motor 66, compare
the resulting motor speed as measured by the encoder 67 with the
desired speed, and modulate the motor signal to generate the
desired torque.
[0082] For procedures that require a sterile environment, the
robotic system may incorporate a drive interface, such as a sterile
adapter connected to a sterile drape, that sits between the
instrument driver and the medical instrument. The chief purpose of
the sterile adapter is to transfer angular motion from the drive
shafts of the instrument driver to the drive inputs of the
instrument while maintaining physical separation, and thus
sterility, between the drive shafts and drive inputs. Accordingly,
an example sterile adapter may comprise of a series of rotational
inputs and outputs intended to be mated with the drive shafts of
the instrument driver and drive inputs on the instrument. Connected
to the sterile adapter, the sterile drape, comprised of a thin,
flexible material such as transparent or translucent plastic, is
designed to cover the capital equipment, such as the instrument
driver, robotic arm, and cart (in a cart-based system) or table (in
a table-based system). Use of the drape would allow the capital
equipment to be positioned proximate to the patient while still
being located in an area not requiring sterilization (i.e.,
non-sterile field). On the other side of the sterile drape, the
medical instrument may interface with the patient in an area
requiring sterilization (i.e., sterile field).
D. Medical Instrument.
[0083] FIG. 13 illustrates an example medical instrument with a
paired instrument driver. Like other instruments designed for use
with a robotic system, medical instrument 70 comprises an elongated
shaft 71 (or elongate body) and an instrument base 72. The
instrument base 72, also referred to as an "instrument handle" due
to its intended design for manual interaction by the physician, may
generally comprise rotatable drive inputs 73, e.g., receptacles,
pulleys or spools, that are designed to be mated with drive outputs
74 that extend through a drive interface on instrument driver 75 at
the distal end of robotic arm 76. When physically connected,
latched, and/or coupled, the mated drive inputs 73 of instrument
base 72 may share axes of rotation with the drive outputs 74 in the
instrument driver 75 to allow the transfer of torque from drive
outputs 74 to drive inputs 73. In some embodiments, the drive
outputs 74 may comprise splines that are designed to mate with
receptacles on the drive inputs 73.
[0084] The elongated shaft 71 is designed to be delivered through
either an anatomical opening or lumen, e.g., as in endoscopy, or a
minimally invasive incision, e.g., as in laparoscopy. The elongated
shaft 66 may be either flexible (e.g., having properties similar to
an endoscope) or rigid (e.g., having properties similar to a
laparoscope) or contain a customized combination of both flexible
and rigid portions. When designed for laparoscopy, the distal end
of a rigid elongated shaft may be connected to an end effector
comprising a jointed wrist formed from a clevis with an axis of
rotation and a surgical tool, such as, for example, a grasper or
scissors, that may be actuated based on force from the tendons as
the drive inputs rotate in response to torque received from the
drive outputs 74 of the instrument driver 75. When designed for
endoscopy, the distal end of a flexible elongated shaft may include
a steerable or controllable bending section that may be articulated
and bent based on torque received from the drive outputs 74 of the
instrument driver 75.
[0085] Torque from the instrument driver 75 is transmitted down the
elongated shaft 71 using tendons within the shaft 71. These
individual tendons, such as pull wires, may be individually
anchored to individual drive inputs 73 within the instrument handle
72. From the handle 72, the tendons are directed down one or more
pull lumens within the elongated shaft 71 and anchored at the
distal portion of the elongated shaft 71. In laparoscopy, these
tendons may be coupled to a distally mounted end effector, such as
a wrist, grasper, or scissor. Under such an arrangement, torque
exerted on drive inputs 73 would transfer tension to the tendon,
thereby causing the end effector to actuate in some way. In
laparoscopy, the tendon may cause a joint to rotate about an axis,
thereby causing the end effector to move in one direction or
another. Alternatively, the tendon may be connected to one or more
jaws of a grasper at distal end of the elongated shaft 71, where
tension from the tendon cause the grasper to close.
[0086] In endoscopy, the tendons may be coupled to a bending or
articulating section positioned along the elongated shaft 71 (e.g.,
at the distal end) via adhesive, control ring, or other mechanical
fixation. When fixedly attached to the distal end of a bending
section, torque exerted on drive inputs 73 would be transmitted
down the tendons, causing the softer, bending section (sometimes
referred to as the articulable section or region) to bend or
articulate. Along the non-bending sections, it may be advantageous
to spiral or helix the individual pull lumens that direct the
individual tendons along (or inside) the walls of the endoscope
shaft to balance the radial forces that result from tension in the
pull wires. The angle of the spiraling and/or spacing there between
may be altered or engineered for specific purposes, wherein tighter
spiraling exhibits lesser shaft compression under load forces,
while lower amounts of spiraling results in greater shaft
compression under load forces, but also exhibits limits bending. On
the other end of the spectrum, the pull lumens may be directed
parallel to the longitudinal axis of the elongated shaft 71 to
allow for controlled articulation in the desired bending or
articulable sections.
[0087] In endoscopy, the elongated shaft 71 houses a number of
components to assist with the robotic procedure. The shaft may
comprise of a working channel for deploying surgical tools,
irrigation, and/or aspiration to the operative region at the distal
end of the shaft 71. The shaft 71 may also accommodate wires and/or
optical fibers to transfer signals to/from an optical assembly at
the distal tip, which may include of an optical camera. The shaft
71 may also accommodate optical fibers to carry light from
proximally-located light sources, such as light emitting diodes, to
the distal end of the shaft.
[0088] At the distal end of the instrument 70, the distal tip may
also comprise the opening of a working channel for delivering tools
for diagnostic and/or therapy, irrigation, and aspiration to an
operative site. The distal tip may also include a port for a
camera, such as a fiberscope or a digital camera, to capture images
of an internal anatomical space. Relatedly, the distal tip may also
include ports for light sources for illuminating the anatomical
space when using the camera.
[0089] In the example of FIG. 13, the drive shaft axes, and thus
the drive input axes, are orthogonal to the axis of the elongated
shaft. This arrangement, however, complicates roll capabilities for
the elongated shaft 71. Rolling the elongated shaft 71 along its
axis while keeping the drive inputs 73 static results in
undesirable tangling of the tendons as they extend off the drive
inputs 73 and enter pull lumens within the elongate shaft 71. The
resulting entanglement of such tendons may disrupt any control
algorithms intended to predict movement of the flexible elongate
shaft during an endoscopic procedure.
[0090] FIG. 14 illustrates an alternative design for an instrument
driver and instrument where the axes of the drive units are
parallel to the axis of the elongated shaft of the instrument. As
shown, a circular instrument driver 80 comprises four drive units
with their drive outputs 81 aligned in parallel at the end of a
robotic arm 82. The drive units, and their respective drive outputs
81, are housed in a rotational assembly 83 of the instrument driver
80 that is driven by one of the drive units within the assembly 83.
In response to torque provided by the rotational drive unit, the
rotational assembly 83 rotates along a circular bearing that
connects the rotational assembly 83 to the non-rotational portion
84 of the instrument driver. Power and controls signals may be
communicated from the non-rotational portion 84 of the instrument
driver 80 to the rotational assembly 83 through electrical contacts
may be maintained through rotation by a brushed slip ring
connection (not shown). In other embodiments, the rotational
assembly 83 may be responsive to a separate drive unit that is
integrated into the non-rotatable portion 84, and thus not in
parallel to the other drive units. The rotational mechanism 83
allows the instrument driver 80 to rotate the drive units, and
their respective drive outputs 81, as a single unit around an
instrument driver axis 85.
[0091] Like earlier disclosed embodiments, an instrument 86 may
comprise of an elongated shaft portion 88 and an instrument base 87
(shown with a transparent external skin for discussion purposes)
comprising a plurality of drive inputs 89 (such as receptacles,
pulleys, and spools) that are configured to receive the drive
outputs 81 in the instrument driver 80. Unlike prior disclosed
embodiments, instrument shaft 88 extends from the center of
instrument base 87 with an axis substantially parallel to the axes
of the drive inputs 89, rather than orthogonal as in the design of
FIG. 13.
[0092] When coupled to the rotational assembly 83 of the instrument
driver 80, the medical instrument 86, comprising instrument base 87
and instrument shaft 88, rotates in combination with the rotational
assembly 83 about the instrument driver axis 85. Since the
instrument shaft 88 is positioned at the center of instrument base
87, the instrument shaft 88 is coaxial with instrument driver axis
85 when attached. Thus, rotation of the rotational assembly 83
causes the instrument shaft 88 to rotate about its own longitudinal
axis. Moreover, as the instrument base 87 rotates with the
instrument shaft 88, any tendons connected to the drive inputs 89
in the instrument base 87 are not tangled during rotation.
Accordingly, the parallelism of the axes of the drive outputs 81,
drive inputs 89, and instrument shaft 88 allows for the shaft
rotation without tangling any control tendons.
E. Navigation and Control.
[0093] Traditional endoscopy may involve the use of fluoroscopy
(e.g., as may be delivered through a C-arm) and other forms of
radiation-based imaging modalities to provide endoluminal guidance
to an operator physician. In contrast, the robotic systems
contemplated by this disclosure can provide for non-radiation-based
navigational and localization means to reduce physician exposure to
radiation and reduce the amount of equipment within the operating
room. As used herein, the term "localization" may refer to
determining and/or monitoring the position of objects in a
reference coordinate system. Technologies such as pre-operative
mapping, computer vision, real-time EM tracking, and robot command
data may be used individually or in combination to achieve a
radiation-free operating environment. In other cases, where
radiation-based imaging modalities are still used, the
pre-operative mapping, computer vision, real-time EM tracking, and
robot command data may be used individually or in combination to
improve upon the information obtained solely through
radiation-based imaging modalities.
[0094] FIG. 15 is a block diagram illustrating a localization
system 90 that estimates a location of one or more elements of the
robotic system, such as the location of the instrument, in
accordance to an example embodiment. The localization system 90 may
be a set of one or more computer devices configured to execute one
or more instructions. The computer devices may be embodied by a
processor (or processors) and computer-readable memory in one or
more components discussed above. By way of example and not
limitation, the computer devices may be in the tower 30 shown in
FIG. 1, the cart shown in FIGS. 1-4, the beds shown in FIGS. 5-10,
etc.
[0095] As shown in FIG. 15, the localization system 90 may include
a localization module 95 that processes input data 91-94 to
generate location data 96 for the distal tip of a medical
instrument. The location data 96 may be data or logic that
represents a location and/or orientation of the distal end of the
instrument relative to a frame of reference. The frame of reference
can be a frame of reference relative to the anatomy of the patient
or to a known object, such as an EM field generator (see discussion
below for the EM field generator). The location data 96 may also be
referred to herein as "state data" which describes a current state
of the distal tip of the medical instrument with respect to a model
(e.g., a skeletal model) of the anatomy of the patient. The state
data may include information such as a position and orientation of
the distal tip of the medical instrument for a given sample period.
For example, when the patient's anatomy is modeled using a skeletal
model based on a midpoint of the luminal network, the position may
take the form of a segment ID and a depth along the segment.
[0096] The various input data 91-94 are now described in greater
detail. Pre-operative mapping may be accomplished through the use
of the collection of low dose CT scans. Pre-operative CT scans are
reconstructed into three-dimensional (3D) images, which are
visualized, e.g., as "slices" of a cutaway view of the patient's
internal anatomy. When analyzed in the aggregate, image-based
models for anatomical cavities, spaces and structures of the
patient's anatomy, such as a patient lung network, may be
generated. Techniques such as center-line geometry may be
determined and approximated from the CT images to develop a 3D
volume of the patient's anatomy, referred to as preoperative model
data 91. The use of center-line geometry is discussed in U.S.
patent application Ser. No. 14/523,760, the contents of which are
herein incorporated in its entirety. Network topological models may
also be derived from the CT-images, and are particularly
appropriate for bronchoscopy.
[0097] In some embodiments, the instrument may be equipped with a
camera to provide vision data 92. The localization module 95 may
process the vision data to enable one or more vision-based location
tracking. For example, the preoperative model data may be used in
conjunction with the vision data 92 to enable computer vision-based
tracking of the medical instrument (e.g., an endoscope or an
instrument advance through a working channel of the endoscope). For
example, using the preoperative model data 91, the robotic system
may generate a library of expected endoscopic images from the model
based on the expected path of travel of the endoscope, each image
linked to a location within the model. Intra-operatively, this
library may be referenced by the robotic system in order to compare
real-time images captured at the camera (e.g., a camera at a distal
end of the endoscope) to those in the image library to assist
localization.
[0098] Other computer vision-based tracking techniques use feature
tracking to determine motion of the camera, and thus the endoscope.
Some feature of the localization module 95 may identify circular
geometries in the preoperative model data 91 that correspond to
anatomical lumens and track the change of those geometries to
determine which anatomical lumen was selected, as well as the
relative rotational and/or translational motion of the camera. Use
of a topological map may further enhance vision-based algorithms or
techniques.
[0099] Optical flow, another computer vision-based technique, may
analyze the displacement and translation of image pixels in a video
sequence in the vision data 92 to infer camera movement. Examples
of optical flow techniques may include motion detection, object
segmentation calculations, luminance, motion compensated encoding,
stereo disparity measurement, etc. Through the comparison of
multiple frames over multiple iterations, movement and location of
the camera (and thus the endoscope) may be determined.
[0100] The localization module 95 may use real-time EM tracking to
generate a real-time location of the endoscope in a global
coordinate system that may be registered to the patient's anatomy,
represented by the preoperative model. In EM tracking, an EM sensor
(or tracker) comprising of one or more sensor coils embedded in one
or more locations and orientations in a medical instrument (e.g.,
an endoscopic tool) measures the variation in the EM field created
by one or more static EM field generators positioned at a known
location. The location information detected by the EM sensors is
stored as EM data 93. The EM field generator (or transmitter), may
be placed close to the patient to create a low intensity magnetic
field that the embedded sensor may detect. The magnetic field
induces small currents in the sensor coils of the EM sensor, which
may be analyzed to determine the distance and angle between the EM
sensor and the EM field generator. These distances and orientations
may be intra-operatively "registered" to the patient anatomy (e.g.,
the preoperative model) in order to determine the geometric
transformation that aligns a single location in the coordinate
system with a position in the pre-operative model of the patient's
anatomy. Once registered, an embedded EM tracker in one or more
positions of the medical instrument (e.g., the distal tip of an
endoscope) may provide real-time indications of the progression of
the medical instrument through the patient's anatomy.
[0101] Robotic command and kinematics data 94 may also be used by
the localization module 95 to provide localization data 96 for the
robotic system. Device pitch and yaw resulting from articulation
commands may be determined during pre-operative calibration.
Intra-operatively, these calibration measurements may be used in
combination with known insertion depth information to estimate the
position of the instrument. Alternatively, these calculations may
be analyzed in combination with EM, vision, and/or topological
modeling to estimate the position of the medical instrument within
the network.
[0102] As FIG. 15 shows, a number of other input data can be used
by the localization module 95. For example, although not shown in
FIG. 15, an instrument utilizing shape-sensing fiber can provide
shape data that the localization module 95 can use to determine the
location and shape of the instrument.
[0103] The localization module 95 may use the input data 91-94 in
combination(s). In some cases, such a combination may use a
probabilistic approach where the localization module 95 assigns a
confidence weight to the location determined from each of the input
data 91-94. Thus, where the EM data may not be reliable (as may be
the case where there is EM interference) the confidence of the
location determined by the EM data 93 can be decrease and the
localization module 95 may rely more heavily on the vision data 92
and/or the robotic command and kinematics data 94.
[0104] As discussed above, the robotic systems discussed herein may
be designed to incorporate a combination of one or more of the
technologies above. The robotic system's computer-based control
system, based in the tower, bed and/or cart, may store computer
program instructions, for example, within a non-transitory
computer-readable storage medium such as a persistent magnetic
storage drive, solid state drive, or the like, that, upon
execution, cause the system to receive and analyze sensor data and
user commands, generate control signals throughout the system, and
display the navigational and localization data, such as the
position of the instrument within the global coordinate system,
anatomical map, etc.
2. Introduction to Registration of Location Sensors
[0105] Embodiments of the disclosure relate to systems and
techniques for registering a coordinate system used by one or more
location sensors with another coordinate system, such as a
coordinate system used by an anatomical model. Registration may
refer to a transformation which can be applied to location sensor
data to map the location sensor data into the coordinate system of
the anatomical model. Thus, registration can be used by a system to
determine the location of one or more location sensor(s) with
respect to the anatomical model based on the location sensor data.
Location sensor(s) may be used to localize the distal end of an
instrument to an anatomical location during a medical procedure.
The location sensor(s) may be positioned at or near the distal end
of the instrument or may be positioned remote from the distal end
of the instrument. Examples of location sensors which may be
positioned at or near the distal end of the instrument include: EM
sensors, vision-based location sensors (e.g., a camera), shape
sensing fibers, etc. Examples of location sensors which may be
positioned remote from the distal end of the instrument include
fluoroscopic imaging devices, robotic data used to control the
position of the instrument via one or more instrument manipulators,
etc.
[0106] The location sensors may be configured to generate location
data indicative of the location of the distal end of the instrument
with respect to a location sensor coordinate system. When the
location sensors are collocated with the distal end of the
instrument, the location data may be representative of the location
of the location sensors themselves, which can then be used to
determine the location of the distal end of the instrument. In
certain embodiments, the location sensor coordinate system may
comprise a set of axes and an origin, which may be defined based on
the particular technology used to implement the location
sensors.
[0107] For example, EM sensors located in or on the instrument may
be configured to measure an EM field generated by an EM field
generator. The properties of the EM field, and thus, the EM values
measured by the EM sensors, may be defined with respect to the
location and orientation of the EM field generator. Thus, the
positioning of the EM field generator may affect the values
measured by the EM sensors and may also define the location and
orientation of the EM coordinate system.
[0108] As described above, a patient's luminal network may be
pre-operatively mapped using, for example, low dose CT scans to
produce a model of the luminal network. Since the model may be
produced via a different technique than used to locate the distal
end of the instrument, the model coordinate system may not be
aligned with the location sensor coordinate system. Accordingly, in
order to use the location sensor coordinate system to track the
location of the instrument with respect to the model, certain
aspects of this disclosure relate to "registering" the location
sensor coordinate system to the model coordinate system. This
registration may include, for example, a translation and/or a
rotation, which can be applied to the location data in order to map
the location data from the location sensor coordinate system into
the model coordinate system.
[0109] Since the model of the luminal network provides a mapping of
the patient's luminal network, the model coordinate system is
"anchored" or defined with respect to the patient. That is, the
frame of reference for the model coordinate system is based on the
location and/or orientation of the patient during the procedure.
One challenge to registering the location sensor coordinate system
to the model coordinate system is that the frame of reference for
the location sensor coordinate system may not be "anchored" or
predefined with respect to the patient. For example, when the
location sensor is embodied as an EM sensor, the frame of reference
for the EM coordinate system may be the EM field generator.
However, in certain implementations, the EM field generator may be
freely positioned within a certain area so that the EM field
generator can be positioned out of the path of other elements of
the robotic surgical system (e.g., robotic arms, C-arm, etc.).
Since the position of the EM field generator, and thus the frame of
reference of the EM coordinate system is not predefined, the system
may be configured to perform a process to register the EM
coordinate system to the model coordinate system.
[0110] One technique for registering the EM coordinate system to
the model coordinate system may include a preoperative step of
identifying a plurality of locations within the preoperative model
and an intraoperative step of providing instructions to a user to
drive the instrument to each of these locations. The system may
instruct the user to drive the instrument to each of the locations,
relying on other forms of navigation (e.g., camera feedback), and
the system may further be configured to receive input from the user
confirming when the instrument is located at each of the identified
locations. Using the confirmations received from the user, the EM
data, and the identified locations within the model, the system may
determine a registration that maps the EM data to the identified
locations. This registration can then be used to map the EM data
representing the location of the distal end of the instrument to
the model for the remainder of the procedure.
[0111] However, the above-described registration process may be
complicated and time consuming for the user. For example, in order
to provide a sufficiently robust registration, the system may be
required to identify a relatively large number of locations (e.g.,
6 or more locations) which are spatially diverse (e.g., the
identified locations may be required to be at least a certain
distance apart from each other). Accordingly, certain aspects of
this disclosure relate to systems and techniques which may provide
a registration between a location sensor coordinate system and a
model coordinate system via a simplified process.
A. EM Navigation-Guided Bronchoscopy.
[0112] Hereinafter, the registration of location sensors will be
described with respect to the embodiment of the registration of EM
sensors for use in an EM navigation-guided bronchoscopic procedure.
However, aspects of this disclosure may also apply to other
location sensors which can produce location data within a
corresponding location sensor coordinate system, as well as to
other medical types of medical procedures.
[0113] A bronchoscope can include a light source and a small camera
that allows a physician to inspect a patient's windpipe and
airways. Patient trauma can occur if the precise location of the
bronchoscope within the patient airways is not known. To ascertain
the location of the bronchoscope, image-based bronchoscopy guidance
systems can use data from the bronchoscope camera to perform local
registrations (e.g., registrations at a particular location within
a luminal network) at bifurcations of patient airways and so
beneficially can be less susceptible to position errors due to
patient breathing motion. However, as image-based guidance methods
rely on the bronchoscope video, they can be affected by artifacts
in bronchoscope video caused by patient coughing or mucous
obstruction, etc.
[0114] EM navigation-guided bronchoscopy is a type of bronchoscopic
procedure that implements EM technology to localize and guide
endoscopic tools or catheters through the bronchial pathways of the
lung. EM navigation-guided bronchoscopy systems can use an EM field
generator that emits a low-intensity, varying EM field and
establishes the position of the tracking volume around the luminal
network of the patient. The EM field is a physical field produced
by electrically charged objects that affects the behavior of
charged objects in the vicinity of the field. EM sensors attached
to the instrument when positioned within the generated field can be
used to track locations and orientations of the instrument within
the EM field. Small currents are induced in the EM sensors by the
varying EM field. The characteristics of these electrical signals
are dependent on the distance and angle between a sensor and the EM
field generator. Accordingly, an EM navigation-guided bronchoscopy
system can include an EM field generator, a steerable instrument
having one or more EM sensors at or near its distal tip, and a
guidance computing system. The EM field generator generates an EM
field around the luminal network of the patient to be navigated,
for example, airways, gastrointestinal tract, or a circulatory
pathway. The steerable channel is inserted through the working
channel of the bronchoscope and tracked in the EM field via the EM
sensor.
[0115] Prior to the start of an EM navigation-guided bronchoscopy
procedure, a virtual, 3D bronchial model can be obtained for the
patient's specific airway structure, for example, from a
preoperative CT chest scan. Using the model and an EM
navigation-guided bronchoscopy system, physicians can navigate to a
desired location within the lung to biopsy lesions, stage lymph
nodes, insert markers to guide radiotherapy or guide brachytherapy
catheters. For example, a registration can be performed at the
beginning of a procedure to generate a mapping between the EM
coordinate system and the model coordinate system. Thus, as the
instrument is tracked during bronchoscopy, the instrument's
position in the model coordinate system becomes nominally known
based on position data from the EM sensor.
[0116] FIG. 16A illustrates an example operating environment 100
implementing one or more aspects of the disclosed navigation
systems and techniques. The operating environment 100 includes
patient 101, a platform 102 supporting the patient 101, a surgical
or medical robotic system 110 guiding movement of an instrument
115, command center 105 for controlling operations of the robotic
system 110, EM controller 135, EM field generator 120, and EM
sensors 125, 130. FIG. 16A also illustrates an outline of a region
of a luminal network 140 within the patient 101, shown in more
detail in FIG. 16B.
[0117] The system 110 can include one or more robotic arms for
positioning and guiding movement of instrument 115 through the
luminal network 140 of the patient 101. Command center 105 can be
communicatively coupled to the robotic system 110 for receiving
position data and/or providing control signals from a user. As used
herein, "communicatively coupled" refers to any wired and/or
wireless data transfer mediums, including but not limited to a
wireless wide area network (WWAN) (e.g., one or more cellular
networks), a wireless local area network (WLAN) (e.g., configured
for one or more standards, such as the IEEE 802.11 (Wi-Fi)),
Bluetooth, data transfer cables, and/or the like. The robotic
system 110 can be any of the systems described above with respect
to FIGS. 1-15. An embodiment of the system 110 is discussed in more
detail with respect to FIG. 16C, and the command center 105 is
discussed in more detail with respect to FIG. 17.
[0118] The instrument 115 may be a tubular and flexible surgical
instrument that is inserted into the anatomy of a patient to
capture images of the anatomy (e.g., body tissue) and provide a
working channel for insertion of other medical instruments to a
target tissue site. As described above, the instrument 115 can be a
procedure-specific endoscope, for example a bronchoscope,
gastroscope, or ureteroscope, or may be a laparoscope or vascular
steerable catheter. The instrument 115 can include one or more
imaging devices (e.g., cameras or other types of optical sensors)
at its distal end. The imaging devices may include one or more
optical components such as an optical fiber, fiber array,
photosensitive substrate, and/or lens(es). The optical components
move along with the tip of the instrument 115 such that movement of
the tip of the instrument 115 results in corresponding changes to
the field of view of the images captured by the imaging devices.
The distal end of the instrument 115 can be provided with one or
more EM sensors 125 for tracking the position of the distal end
within an EM field generated around the luminal network 140. The
distal end of the instrument 115 is further described with
reference to FIG. 18 below.
[0119] EM controller 135 can control EM field generator 120 to
produce a varying EM field. The EM field can be time-varying and/or
spatially varying, depending upon the embodiment. The EM field
generator 120 can be an EM field generating board in some
embodiments. Some embodiments of the disclosed patient navigation
systems can use an EM field generator board positioned between the
patient and the platform 102 supporting the patient, and the EM
field generator board can incorporate a thin barrier that minimizes
any tracking distortions caused by conductive or magnetic materials
located below it. In other embodiments, an EM field generator board
can be mounted on a robotic arm, for example, similar to those
shown in the robotic system 110, which can offer flexible setup
options around the patient.
[0120] FIG. 16B illustrates an example luminal network 140 that can
be navigated in the operating environment 100 of FIG. 16A. The
luminal network 140 includes the branched structure of the airways
150 of the patient 101, the trachea 154 leading to the main carina
156 (typically the first bifurcation encountered during
bronchoscopy navigation), and a nodule (or lesion) 155 that can be
accessed as described herein for diagnosis and/or treatment. As
illustrated, the nodule 155 is located at the periphery of the
airways 150. The instrument 115 may comprise a sheath 141 having a
first diameter and thus the distal end of the sheath 141 may not
able to be positioned through the smaller-diameter airways around
the nodule 155. Accordingly, a scope 145 extends from the working
channel of the instrument 115 and across the remaining distance to
the nodule 155. The scope 145 may have a lumen through which
instruments, for example, biopsy needles, cytology brushes, and/or
tissue sampling forceps, can be passed to the target tissue site of
nodule 155. In such implementations, both the distal end of the
sheath 141 and the distal end of the scope 145 can be provided with
EM sensors for tracking their respective positions within the
airways 150.
[0121] In some embodiments, a 2D display of the 3D luminal network
model as described herein, or a cross-section of a 3D model, can
resemble FIG. 16B. Estimated position information can be overlaid
onto such a representation.
[0122] FIG. 16C illustrates an example robotic arm 175 of the
robotic system 110 for guiding instrument movement in through the
luminal network 140 of FIG. 16B. The robotic arm 175 can include
robotic arms 12, 39 described above in some embodiments, and is
coupled to base 180, which can include a cart base 15, column 37 of
patient platform 38, or a ceiling-based mount in various
embodiments. As described above, the robotic arm 175 includes
multiple arm segments 170 coupled at joints 165, which provides the
robotic arm 175 multiple degrees of freedom.
[0123] The robotic arm 175 may be coupled to an instrument
manipulator 190, for example instrument manipulator 62 described
above, e.g., using a mechanism changer interface (MCI) 160. The
instrument manipulator 190 can be removed and replaced with a
different type of instrument manipulator, for example, a first type
of instrument manipulator configured to manipulate an endoscope or
a second type of instrument manipulator configured to manipulate a
laparoscope. The MCI 160 includes connectors to transfer pneumatic
pressure, electrical power, electrical signals, and optical signals
from the robotic arm 175 to the instrument driver 190. The MCI 160
can be a set screw or base plate connector. The instrument
manipulator 190 manipulates instruments, for example, the
instrument 115 using techniques including direct drive, harmonic
drive, geared drives, belts and pulleys, magnetic drives, and the
like. The MCI 160 is interchangeable based on the type of
instrument manipulator 190 and can be customized for a certain type
of surgical procedure. The robotic 175 arm can include a joint
level torque sensing and a wrist at a distal end.
[0124] Robotic arm 175 of the robotic system 110 can manipulate the
instrument 115 using tendons as described above to deflect the tip
of the instrument 115. The instrument 115 may exhibit nonlinear
behavior in response to forces applied by the elongate movement
members. The nonlinear behavior may be based on stiffness and
compressibility of the instrument 115, as well as variability in
slack or stiffness between different elongate movement members.
[0125] The base 180 can be positioned such that the robotic arm 175
has access to perform or assist with a surgical procedure on a
patient, while a user such as a physician may control the robotic
system 110 from the comfort of the command console. The base 180
can be communicatively coupled to the command console 105 shown in
FIG. 16A.
[0126] The base 180 can include a source of power 182, pneumatic
pressure 186, and control and sensor electronics 184--including
components such as a central processing unit, data bus, control
circuitry, and memory--and related actuators such as motors to move
the robotic arm 175. The electronics 184 can implement the
navigation control techniques described herein. The electronics 184
in the base 180 may also process and transmit control signals
communicated from the command console. In some embodiments, the
base 180 includes wheels 188 to transport the robotic system 110
and wheel locks/brakes (not shown) for the wheels 188. Mobility of
the robotic system 110 helps accommodate space constraints in a
surgical operating room as well as facilitate appropriate
positioning and movement of surgical equipment. Further, the
mobility allows the robotic arm 175 to be configured such that the
robotic arm 175 does not interfere with the patient, physician,
anesthesiologist, or any other equipment. During procedures, a user
may control the robotic arm 175 using control devices, for example,
the command console.
[0127] FIG. 17 illustrates an example command console 200 that can
be used, for example, as the command console 105 in the example
operating environment 100. The command console 200 may include a
console base 201, one or more displays 202 (e.g., monitors), and
one or more control modules (e.g., a keyboard 203 and joystick
204). In some embodiments, one or more of the command console 200
functionality may be integrated into a base 180 of the robotic
system 110 or another system communicatively coupled to the robotic
system 110. A user 205, e.g., a physician, remotely controls the
robotic system 110 from an ergonomic position using the command
console 200.
[0128] The console base 201 may include a central processing unit,
a memory unit, a data bus, and associated data communication ports
that are responsible for interpreting and processing signals such
as camera imagery and tracking sensor data, e.g., from the
instrument 115 shown in FIGS. 16A-16C. In some embodiments, both
the console base 201 and the base 180 perform signal processing for
load-balancing. The console base 201 may also process commands and
instructions provided by the user 205 through the control modules
203 and 204. In addition to the keyboard 203 and joystick 204 shown
in FIG. 17, the control modules may include other devices, for
example, computer mice, trackpads, trackballs, control pads,
controllers such as handheld remote controllers, and sensors (e.g.,
motion sensors or cameras) that capture hand gestures and finger
gestures. A controller can include a set of user inputs (e.g.,
buttons, joysticks, directional pads, etc.) mapped or linked to an
operation of the instrument (e.g., articulation, driving, water
irrigation, etc.).
[0129] The displays 202 may include electronic monitors (e.g., LCD
displays, LED displays, touch-sensitive displays), virtual reality
viewing devices, e.g., goggles or glasses, and/or other display
devices. In some embodiments, the display modules 202 are
integrated with the control modules, for example, as a tablet
device with a touchscreen. In some embodiments, one of the displays
202 can display a 3D model of the patient's luminal network and
virtual navigation information (e.g., a virtual representation of
the end of the endoscope within the model based on EM sensor
position) while the other of the displays 202 can display image
information received from the camera or another sensing device at
the end of the instrument 115. In some implementations, the user
205 can both view data and input commands to the system 110 using
the integrated displays 202 and control modules. The displays 202
can display 2D renderings of 3D images and/or 3D images using a
stereoscopic device, e.g., a visor or goggles. The 3D images
provide an "endo view" (i.e., endoscopic view), which is a computer
3D model illustrating the anatomy of a patient. The "endo view"
provides a virtual environment of the patient's interior and an
expected location of an instrument 115 inside the patient. A user
205 compares the "endo view" model to actual images captured by a
camera to help mentally orient and confirm that the instrument 115
is in the correct--or approximately correct--location within the
patient. The "endo view" provides information about anatomical
structures, e.g., the shape of airways, circulatory vessels, or an
intestine or colon of the patient, around the distal end of the
instrument 115. The display modules 202 can simultaneously display
the 3D model and CT scans of the anatomy the around distal end of
the instrument 115. Further, the display modules 202 may overlay
the already determined navigation paths of the instrument 115 on
the 3D model and CT scans.
[0130] In some embodiments, a model of the instrument 115 is
displayed with the 3D models to help indicate a status of a
surgical procedure. For example, the CT scans identify a lesion in
the anatomy where a biopsy may be necessary. During operation, the
display modules 202 may show a reference image captured by the
instrument 115 corresponding to the current location of the
instrument 115. The display modules 202 may automatically display
different views of the model of the instrument 115 depending on
user settings and a particular surgical procedure. For example, the
display modules 202 show an overhead fluoroscopic view of the
instrument 115 during a navigation step as the instrument 115
approaches an operative region of a patient.
[0131] FIG. 18 illustrates the distal end 300 of an example
instrument having imaging and EM sensing capabilities as described
herein, for example, the instrument 115 of FIGS. 16A-16C. In FIG.
18, the distal end 300 of the instrument includes an imaging device
315, illumination sources 310, and ends of EM sensor coils 305. The
distal end 300 further includes an opening to a working channel 320
of the endoscope through which surgical instruments, such as biopsy
needles, cytology brushes, and forceps, may be inserted along the
endoscope shaft, allowing access to the area near the endoscope
tip.
[0132] EM coils 305 located on the distal end 300 may be used with
an EM tracking system to detect the position and orientation of the
distal end 300 of the endoscope while it is disposed within an
anatomical system. In some embodiments, the coils 305 may be angled
to provide sensitivity to EM fields along different axes, giving
the disclosed navigational systems the ability to measure a full 6
degrees of freedom: three positional and three angular. In other
embodiments, only a single coil may be disposed on or within the
distal end 300 with its axis oriented along the endoscope shaft of
the instrument. Due to the rotational symmetry of such a system, it
is insensitive to roll about its axis, so only 5 degrees of freedom
may be detected in such an implementation.
B. Techniques for Location Sensor Registration.
[0133] As discussed above, location sensors may be used to track
the location of a portion of an instrument (e.g., the distal end of
the instrument) with respect to a model of an anatomy of a patient
through which the instrument is driven during a medical procedure.
It is to be appreciated that the model may be generated based on
pre-operative measurements and the location sensor may function
based on an independent coordinate system. In order to accurately
determine the location of the instrument using the location
sensors, the location sensor coordinate system is registered to the
model coordinate system, which provides a transformation that can
be applied to measurements from the location sensors to arrive at
corresponding positions within the model coordinate system. FIG. 17
illustrates an example command console 200 that can be used, for
example, as the command console 105 in the example operating
environment 100. The command console 200 may include a console base
201, one or more display 202 (e.g., monitors), and one or more
control modules (e.g., a keyboard 203 and joystick 204). In some
embodiments, one or more of the command console 200 functionality
may be integrated into a base 180 of the robotic system 110 or
another system communicatively coupled to the robotic system 110. A
user 205, e.g., a physician, remotely controls the robotic system
110 from an ergonomic position using the command console 200.
[0134] In certain implementations, the location sensor coordinate
system can be registered to the model coordinate system based on
location sensor data taken while the instrument is driven within
the patient's anatomy. The amount and type of data required for
registering the location sensor coordinate system to the coordinate
system of the model of the anatomy may depend on the shape of a
given anatomy. For example, one technique for registering a
location sensor coordinate system to a model coordinate system
involves maintaining a history of the data received from the
location sensor(s) and matching the shape formed by the location
data history to the candidate paths along which the instrument can
travel based on the model of the anatomy. This technique may be
more successful in finding a registration between the location
sensor coordinate system and the model coordinate system for
anatomies which have a certain amount of asymmetry.
[0135] FIG. 19 illustrates an example luminal network in which
location sensor registration can be performed in accordance with
aspects of this disclosure. In the embodiment of FIG. 19, the
illustrated luminal network 400 corresponds to a patient's airway
and includes a first-generation airway 405 (e.g., a trachea) which
branches into two second-generation airways 415 and 420 (e.g.,
primary bronchi) at a main carina 410. Also illustrated is a target
425 (e.g., a lesion or nodule within the luminal network 400) to
which the system may drive the instrument during a medical
procedure. A target path 430 provides a planned route along which
the instrument can be driven to reach the target 425. Depending on
the embodiment, the system may automatically generate the target
path 425 based on the pre-operatively scanned model of the luminal
network 400 and the location of the target 425. In other
embodiments, the target path 425 may be selected by a user during
pre-operative planning. The system may display an illustration of
the target path 430 with respect to the model on a display to
provide the user with an indication of the direction in which to
drive the instrument to reach the target 425. In certain
embodiments, the target path 430 may include only a direct path to
the target 425 which does not traverse the same portion of a
luminal network more than once (i.e., traversing the target path
425 does not involve advancing down a segment of the luminal
network and retracting the instrument back along the same
segment).
[0136] As should be appreciated the airways defined by the
second-generation branches 415 and 420 may not be symmetrical, but
instead have different lengths and form different angles with the
first-generation airway 405. In certain registration techniques in
accordance with this disclosure, so called contra-lateral
registration, leverage this asymmetry between the branches 415 and
420 to improve instrument registration. Embodiments can leverage
the asymmetry by driving the instrument along a contra-lateral
route 435, which may include driving the instrument into the
second-generation airway 415 that is contra-lateral to the airway
on the target path 430, retract back to the first-generation airway
405, and then drive to the second-generation airway on the path
430. As is discussed below, embodiments may additionally include
features to facilitate the contra-lateral registration, such as
automatically detecting the contra-lateral branch 415 and
automatically determining when the distance traversed by the
instrument along the contra-lateral branch 415 is sufficient.
[0137] To better explain the use of the contra-lateral route 435,
the route or trace defined by the data output from the location
sensors during the registration process (including the
contra-lateral route 435) can be compared to the various shapes
defined by the model of the luminal network 400. Due to the
asymmetrical shape formed by the luminal network 400, the route
defined by the location sensor data during the registration process
may uniquely correspond to a single portion of the model of the
luminal network 400, namely, the shape defined by the
first-generation airway 405 and each of the second-generation
airways 415 and 420. Thus, the registration between the location
sensor coordinate system and the model coordinate system may be
defined based on a transformation between the route or trace
defined by the location sensor data (e.g., the contra-lateral route
435) during the registration process and the shape defined by the
first-generation airway 405 and each of the second-generation
airways 415 and 420.
[0138] Although FIG. 19 provides an example of a patient's airway
as an embodiment of a luminal network, aspects of this disclosure
may also apply to registration of location sensors used to navigate
other luminal networks, and in particular, luminal networks which
are at least partially asymmetric. For example, aspects of this
disclosure may be applied to a gastro-intestinal network, a urinary
tract, a vascular network, etc. Thus, aspects of this disclosure
relate to the registration of location sensors based on location
data received while driving an instrument along at least a portion
of an asymmetrical route within a luminal network.
[0139] FIG. 20A is a flowchart illustrating an example method
operable by a surgical robotic system, or component(s) thereof, for
contra-laterally registering a location sensor coordinate system in
accordance with aspects of this disclosure. It is to be appreciated
that the steps of method 500 illustrated in FIG. 20A may be
performed by a processor of a surgical robotic system. For
convenience, the method 500 is described as performed by the
processor of the system. When relevant to the description of the
various steps of the method 500, reference will be made to the
luminal network 400 illustrated in FIG. 19 to describe one
embodiment of the method 500 below.
[0140] The processor may be included as a part of a system,
including an instrument having a set of one or more location
sensors. The set of location sensors may be configured to generate
location data indicative of a position of the set of location
sensors in a location sensor coordinate system. The location
sensors may be located at or near a distal end of the instrument
(e.g., see FIG. 18), and thus, the location data may be indicative
of the location of the distal end of the instrument. The system may
further include a set of instrument manipulators configured to
control movement of the distal end of the instrument and at least
one computer-readable memory in communication with the processor
and having stored thereon a model of a luminal network of a
patient. The model may include a target within a model coordinate
system and a path to the target. The memory may further have stored
thereon computer-executable instructions to cause the set of
processors to perform the method 500.
[0141] The method 500 begins at block 501. At block 505, the
processor provides a first set of commands to the set of instrument
manipulators to drive the instrument along a first branch (e.g., a
contra-lateral branch 415) of the luminal network. In some
embodiments, the first set of command may be generated based on
user input received from a set of one or more user input devices.
Thus, the processor may cause user instructions to be provided to a
user which include instructions to follow the set of movements
associated with the registration process (e.g., to drive the
instrument along a first portion of the contra-lateral registration
route 435). The system may then receive the user input
corresponding to the user instructions and generate the first set
of command for movement of the instrument along the first branch.
As illustrated in FIG. 19, first branch 415 is located outside of
the target path 430 to the target 430. Thus, the first set of
commands may cause the instrument manipulators to drive the
instrument along the first portion of the contra-lateral
registration route 435 down the contra-lateral branch 415.
[0142] At block 510, the processor tracks a set of one or more
registration parameters during the driving of the instrument along
the first branch. The registration parameters may be any data that
can be tracked by the system and used to determine whether
sufficient data has been collected by the system to perform
registration between the location sensor coordinate system and the
model coordinate system. At block 515, the processor determines
that the set of registration parameters satisfy a registration
criterion. The registration parameters satisfying the registration
criterion may be indicative of the instrument travelling a
sufficient distance along the contra-lateral branch 415 and the
registration process can continue with the instrument being
retracted back to the target path 430. A more detail embodiment for
tracking the registration parameters and determining whether the
registration parameters satisfy the registration criterion is
provided below in connection with FIG. 20B.
[0143] At block 520, the processor provides a second set of
commands to the set of instrument manipulators to return the
instrument back to the target path 430 and to drive the instrument
along a second branch (e.g., the lateral branch 420). As
illustrated in FIG. 19, the branch 420 is located along the target
path 430 to the target 425. The processor may drive the instrument
along the remainder of the contra-lateral registration route 435,
continuing down the lateral branch 420.
[0144] At block 525, the processor determines a registration
between the location sensor coordinate system and the model
coordinate system based on the location data received from the set
of location sensors during the driving of the instrument along the
first branch and the second branch (e.g., along the contra-lateral
registration route 435). By confirming that the registration
parameters satisfy the registration criterion in block 515 prior to
providing the commands to retract the instrument back to the
lateral branch 420, the processor can ensure that sufficient
location data is collected to determine the registration. The
method 500 ends at block 530.
[0145] In certain embodiments, the registration between the
location sensor coordinate system and the model coordinate system
may be further based on the first set of commands referenced in
step 505 and the second set of commands from step 520. That is, the
first and second sets of commands may be robot data which provided
to the instrument manipulator(s) to control the movement of the
instrument. Since the first and second sets of commands are used to
control the movement of the instrument, the processor may be able
to determine the location of the instrument when moved based on the
first and second sets of commands. Thus, the processor may be able
to determine the location of the distal end of the instrument with
respect to the model based on the robot data used to drive the
instrument. As an example, if the distal end of the instrument is
located at or near the carina (see the carina 410 illustrated in
FIG. 19) and positioned to drive down the first branch (e.g., the
contra-lateral branch 415), after providing an insertion command to
the instrument, the processor may determine that the distal end of
the instrument has been inserted into the first branch by the
amount instructed in the insertion command.
[0146] The processor may further be configured to generate the
first and second sets of commands, provided to the instrument
manipulator, based on user input received from a set of one or more
user input devices. Thus, the driving of the instrument may be
performed manually based on user input received by the system.
[0147] As discussed above, the registration may include a
transformation that can map data from the location sensor
coordinate system to the model coordinate system. The
transformation may include a translation and/or a rotation that can
be applied to location sensor data. To aid in determining the
registration which correctly maps data from the location sensor
coordinate system to the model coordinate system, the processor may
identify a known location in each of the two coordinate systems
which can be used as an anchor between the location sensor
coordinate system and the model coordinate system. With reference
to FIG. 19, the carina 410 can be automatically identified from the
model of the luminal network and the user can easily navigate the
instrument to the carina 410 and provide feedback to the processor
indicative of the location of the carina 410.
[0148] In certain embodiments, the system may also generate guiding
instructions to determine an anchor point at a known location in
each of the location sensor and model coordinate systems. The
guiding instructions may include instructions to the user to drive
the distal end of the instrument to touch the carina 410 and then
retract the instrument after touching the carina 410. Based on user
input, the processor may provide commands to drive the instrument
to the carina 410 and retract the instrument after reaching the
carina 410. Thus, by identifying the location of the instrument
just prior to the retraction, the processor can determine that the
identified location within the location sensor coordinate system
corresponds to the location of the carina 410. The location of the
carina 410 in each of the two coordinate systems can then be used
as once piece of data to determine the transformation mapping the
location sensor coordinate system to the model coordinate
system.
[0149] In another example embodiment, rather than requiring the
user to indicate the location of the carina 410 by retracting the
instrument, the processor may determine the location of the
instrument with respect to the model using a camera included on the
distal end of the instrument. The user may use images captured by
the camera and provided to the display to navigate through the
luminal network. In one embodiment, images obtained by the camera
may be displayed to the user in real-time. The processor may be
configured to determine a position of the distal end of the
instrument based on an analysis of an image received from the
camera. Any image processing technique that can determine the
features of the interior of the luminal network may be used to
determine the position of the distal end of the instrument with
respect to the model. The processor may further determine that the
distal end of the distal end of the instrument is within a
threshold distance from the first location (e.g., the carina 410)
based on determined position of the distal end of the
instrument.
[0150] FIG. 20B is a flowchart illustrating an example method
operable by a surgical robotic system, or component(s) thereof, for
determining whether sufficient location data has been received to
facilitate contra-lateral registration in accordance with aspects
of this disclosure. It is to be appreciated that the steps of
method 550 illustrated in FIG. 20B may be performed by a processor
of a surgical robotic system. For convenience, the method 550 is
described as performed by the processor of the system. The steps of
method 550 may be performed as an implementation of block(s) 510
and 515 of FIG. 20A.
[0151] The method 550 begins at block 551. At block 555, the
processor receives raw location data and state data. As used herein
"raw location data" may refer to location data indicative of a
location within the location sensor coordinate system. Thus, "raw
location data" may be location data that is representative of a
location within the instrument coordinate frame rather than the
model coordinate frame. Prior to performing the registration
process and determining a registration between the location sensor
coordinate system and the model coordinate system, the processor
cannot map the location sensor data to the model coordinate system.
Thus, it will be appreciated that the location data received prior
to the completion of the registration process is unregistered or
raw location data.
[0152] The state data may refer to data produced by the processor
which is indicative of the location of the instrument within the
model. For example, the localization system 90 illustrated in FIG.
15 may be used to produce location data 96 (also referred to as
state data), which can be used in the methods 500 and 550. The
state data may include depth information, such as the current depth
of the instrument in a given segment or an insertion depth within
the anatomical model. The state data may also include an
orientation of the distal end of the instrument in the model
coordinate frame. In certain embodiments, the processor may receive
the raw location data and state data throughout the registration
process 500 illustrated in FIG. 20A.
[0153] At block 560, the processor may store the location data and
state data collected during a registration process, such as the
registration process performed via the method 500. The registration
process may include a choreographed set of movements of the
instrument which may be related to the shape of the luminal
network. The set of movements may also be based on a defined target
path 430 to a target 425 within the model. The registration process
may involve providing a first set of commands to the set of
instrument manipulators to drive the instrument along a first
branch of the luminal network, where the first branch is on the
contra-lateral branch 415 and, thus, outside of the target path 430
to the target 425. The registration process may also involve
providing commands to bring the instrument back to and continue
along the target path 430 to the target site 425. The choreographed
set of movements may include the set(s) of commands required to
drive the distal end of the instrument along the path defined by
the contra-lateral registration route 435. The processor may track
a set of one or more registration parameters during the driving of
the instrument along the first branch, such as depth
information.
[0154] At block 565, the processor may determine whether sufficient
location sensor data has been collected as part of the
contra-lateral phase of the registration process based on the
registration parameters being tracked. In one embodiment, the
processor may use registration parameters such as depth information
(e.g., an insertion depth of the instrument) to determine whether
the instrument has been driven a sufficient distance along the
contra-lateral branch 415 of the contra-lateral route 435. In
certain embodiments, after one registration criterion is satisfied,
the processor may provide a second set of commands to the set of
instrument manipulators to return the instrument back to the target
path 430 and to drive the instrument towards the target site along
a second branch. As the instrument continues along the target site,
the processor may continue tracking the instrument location data
and state data for the registration process.
[0155] By determining whether the instrument has been driven a
sufficient distance along the contra-lateral branch 415, the system
may be able to reduce the amount of input required from the user,
thereby reducing the chances of user-error. For example, certain
registration processes may require the user to drive to a plurality
of defined locations and provide an input to the system indicating
that the instrument has been driven to the defined locations. By
eliminating this type of required user input, aspects of this
disclosure can improve the ease of the registration process and
reduce potential sources of user error.
[0156] At block 570, the processor may register the location
coordinate system to the model coordinate system using the location
data and state data tracked during the registration process (e.g.,
location data and state data tracked along the contra-lateral route
435 and the target path 430). As discussed above, this may include
matching the shape of the path taken by the instrument as tracked
using the location sensors to the shapes of the luminal network
defined by the skeletal structure of the model. In certain
embodiments, the shape of the model having the lowest difference
from the tracked path is selected and used to determine a
registration between the location sensor coordinate system and the
model coordinate system. It is to be appreciated that because the
tracked path includes the contra-lateral branch 415, embodiments
may reduce the likelihood that the tracked path matches to other
candidate paths in the model. The method 550 ends at block 575.
[0157] In determining the registration, the processor may be
further configured to match the shapes defined by histories of the
location sensor data and robot data. Thus, in certain
implementations, the processor may be configured to generate a set
of location data points representative of the location of the
distal end of the instrument with respect to the location
coordinate system while driving the instrument along the
contra-lateral registration route. The processor may further
generate a set of model points representative of the location of
the distal end of the instrument with respect to the model
coordinate system while driving the instrument along the
contra-lateral registration route. The processor may generate the
model points based on the history of robot data and the model. The
two sets of points may be used by the processor to determine the
registration between the location coordinate system and the model
coordinate system is based on determining a registration which maps
the set of location data points in the location coordinate system
to the second set of model points in the model coordinate
system.
[0158] FIG. 21 is a diagram illustrating location data with respect
to a model of a luminal network in accordance with aspects of this
disclosure. In the example of FIG. 21, the diagram 600 includes
model 602 of a pre-operative scan of the luminal network, which may
also include a skeleton 605 defined by the midpoints or
center-points along each of the airways defined by the model 602.
In particular, the skeleton 605 includes a series of segments, each
located at the midpoint of corresponding lumens in the luminal
network. Also illustrated is ground truth data 610 representing the
actual or true location of the distal end of the instrument during
a contra-lateral registration process relative to the anatomy. The
ground truth data 610 shown in FIG. 21 may have been generated by a
testing tool that is not normally used during a procedure to
highlight the accuracy of the contra-lateral registration process.
In the illustrated example, a target 625 may be located on the left
side of the figure. Accordingly, during a registration procedure,
the instrument may be driven from the first-generation airway 630
into the contra-lateral second-generation airway 635. Thereafter,
the instrument may be retracted back into the first-generation
airway 630 and advanced into the lateral second-generation airway
640 located along a path to the target 625.
[0159] The system may also track the state data 615 representing
the location of the instrument along the skeleton of the model 605.
As discuss above, the processor may determine the state data based
on data received from one or more different sources of data
indicative of the location of the distal end of the instrument
(e.g., via the localization module 95 of FIG. 15). Once sufficient
data is received during the registration process, a registration
transformation can be applied to the raw location data to generate
registered location data 620. As shown in FIG. 21, the registered
location data 620 may closely track the ground truth data 610.
After the location data has been registered, the processor may use
the registered location data 620 as an input in determining the
state data 615.
[0160] FIG. 22 is a diagram illustrating an example of registration
of location data without preforming a contra-lateral registration
process in accordance with aspects of this disclosure. In this
example, when a contra-lateral registration process is not
performed (e.g., the instrument is not driven down a contra-lateral
branch) the raw location data 705 may substantially match two
different candidate paths 710 and 715 within the model. That is,
each of the two candidate paths 710 and 715 may have a similar
shape such that a rotation and/or translation of the raw location
data 705 may substantially match both paths 710 and 715. However,
since the two paths 710 and 715 diverge, selecting the incorrect
path 715 for registration may cause the location data to provide an
incorrect indication of the location of the instrument when driven
past the divergence between the two paths 710 and 715. In contrast,
by performing a contra-lateral registration process in accordance
with aspects of this disclosure, the incorrect candidate
registration path 715 can be removed from the set of candidate
registrations since a registration based on the incorrect candidate
registration path 715 would not provide a match in shape along the
contra-lateral route taken by the instrument (see, e.g., FIG.
21).
[0161] As discussed above, the contra-lateral registration
procedure may provide a more accurate and more robust registration
when the first branch and the second branch are asymmetrical (e.g.,
the second-generational segments). Thus, in certain embodiments, a
processor may select an asymmetrical branching of the luminal
network for the contra-lateral registration procedure. This
selection of the location within the luminal network may also
reduce the number of possible solutions to the matching between the
location data and the model, leading to a more robust registration
procedure. In the bronchoscopy example, driving the instrument into
a contra-lateral branch before proceeding along the path to the
target may provide sufficient raw location data to facilitate the
registration of the location sensors to the model coordinate
system. Accordingly, in certain embodiments, the first branch is
located on a contra-lateral side of the luminal network with
respect to the target.
C. Location Sensor Registration Planning.
[0162] Aspects of this disclosure also relate to pre-operative
planning which may involve determining instructions and/or
criterion related to a location sensor registration procedure. FIG.
23 is a flowchart illustrating an example method operable by a
surgical robotic system, or component(s) thereof, for pre-operative
planning in accordance with aspects of this disclosure. The
procedure 800 for pre-operative planning may be operable by a
surgical robotic system, or component(s) thereof, for pre-operative
planning in accordance with aspects of this disclosure. For
example, aspects of the method 800 for pre-operative planning may
be performed by a command console, such as the command console 200
illustrated in FIG. 17 or may be performed by a processor (or a set
of processors) of a surgical robotic system, which may be included
as part of the command console. For convenience, the method for
pre-operative planning is described as performed by the processor
of the system. In certain embodiments, the system may also include
at least one computer-readable memory in communication with the set
of processors and having stored thereon a model of a luminal
network of a patient. The model comprises a target within a model
coordinate system and a path to the target. The memory may also
store computer-executable instructions to cause the set of
processors to perform the method 800.
[0163] The method 800 begins at block 801. At block 905, the
processor provides instructions to display the luminal network via
a display device. In particular, the processor may provide
instructions to display the luminal network via a display device.
This may involve, for example, the processor retrieving a model of
the luminal network from the memory and displaying the model to be
viewed by a user. The display of the model may involve displaying,
for example, the 3D model of the luminal network generated based on
preoperative scans of the luminal network. In other embodiments,
the display of the model may involve displaying the skeleton and/or
a more detailed segmented image generated based on preoperative
scans of the luminal network (as shown in FIGS. 19, 21 and 22).
[0164] At block 810, the processor receives an indication of a
location of a target within the model coordinate system. For
example, the processor may receive an indication from a user, via a
user input device, of a target portion of the model at which at
least a portion of a medical procedure is to be performed. The
target may be, for example, a desired location within the lung to
biopsy lesions, stage lymph nodes, insert markers to guide
radiotherapy or guide brachytherapy catheters. In other
embodiments, the system can automatically detect or otherwise
determine the target location 425 based on detecting features in
the preoperative scan that are indicative of a tumor.
[0165] At block 815, the processor identifies a first branch (e.g.,
a branch located on a contra-lateral side of the luminal network,
such as the contra-lateral branch 415 of FIG. 19) and a second
branch (a branch located on the lateral side of the luminal network
such as lateral branch 420 of FIG. 19) in the luminal network.
Since the identified first and second branches are respectively
located on the contra-lateral and lateral sides of the luminal
network with respect to the location of the target, the first
branch may be located outside of the path to the target and the
second branch may be located along the path to the target.
[0166] In certain embodiments, based on the model and the selected
target, the processor may automatically identify certain segments
of the model which may be traversed by the instrument to aid in
registration of the location sensors. This may include the
processor identifying the first branch as a branch located on a
contra-lateral side of the luminal network and the second branch as
a branch located on a lateral side of the luminal network. In
certain embodiments, the first and second branches may be
second-generation branches of the luminal network, such as branches
415 and 420 illustrated in FIG. 19. The processor may further be
configured to determine that the shape formed by the first and
second branches is sufficiently unique within the luminal network
such that, when the instrument is driven along a contra-lateral
registration route defined by the second-generation branches, no
other shape within the model will match the path taken by the
instrument during the contra-lateral registration process. This
determination may be performed by comparing the shape of the first
and second branches with other possible shapes in the model to
determine whether there exists any possible conflicts in
shapes.
[0167] As discussed above, certain registration processes may
require the user to drive the instrument to a plurality of defined
locations within the luminal network and provide an indication to
the system when the instrument is located at the defined locations.
This technique may also require the user to identify the defined
locations during a pre-operative planning stage. However, since the
processor may automatically identify a contra-lateral route which
can be used for the registration process, the necessary steps for
the user during the pre-operative planning stage can be
reduced.
[0168] At block 820, the processor generates a set of guiding
instructions for driving the distal end of the instrument along the
first branch, back to the path from the first branch, and along the
second branch. Thus, the set of instructions may define a
contra-lateral registration route, such as the contra-lateral
registration route 435 of FIG. 19. The guiding instructions may be
stored in memory to be provided to a user during the medical
procedure. During the medical procedure, location data received
from the set of one or more locations sensors during the driving of
the instrument according to the instructions may facilitate a
registration between the a location coordinate system of the
location data and the model coordinate system. The registration may
include at least one of a translation and a rotation between the
location coordinate system and the model coordinate system. At
block 825, the processor determines a registration criterion for
one or more registration parameters tracked during the driving of
the instrument along the first branch. The method 800 ends at block
830.
[0169] The registration criterion may relate to the amount of
location data required for registration of the location sensor
coordinate system to the model coordinate system. For example, the
criterion may specify a required distance of travel for the
instrument along the contra-lateral branch before the instrument
can be returned back to the path from the first branch. The
registration criterion may also depend on the specific shape of the
patient's anatomy. For example, airways for some patients may have
a larger discrepancy between the shapes and angles formed between
the first and second branches than for other patients. When the
differences between the first and second branches are more
pronounced, it may not be necessary for the instrument to travel as
far down the first branch to receive sufficient data for
registration. In other embodiments, the registration criterion may
be set based on a threshold determined to provide sufficient
location data for registration for the majority of patients for the
particular procedure which will be performed.
[0170] The registration parameters may include an insertion depth
of the instrument into the contra-lateral branch. In this
embodiment, the set of registration parameters satisfy the
registration criterion in response to the insertion depth into the
first branch being greater than a threshold insertion depth. For
example, the registration criterion may include instructions to
drive the instrument along at least 50% of the contra-lateral
branch before returning to the first-generation branch on the path.
The specific value may be different depending on the particular
anatomy involved in the medical procedure and/or based on an
analysis of the variation in the shapes of the anatomy in the
general population.
[0171] Depending on the particular medical procedure, the processor
may also determine whether the first branch and the second branch
are asymmetrical. The processor may identify the first and second
branches in response to determining that the first and second
branches are asymmetrical. As discussed above, the registration
process may be more accurate for asymmetrical paths and/or
asymmetrically shaped luminal networks. Thus, the processor may
select a bifurcation in the luminal network having an asymmetrical
shape for the location at which the registration process is to be
performed. In certain embodiments, such as for an airway, one
branch at which the registration process can be performed is the
branch from the trachea into the main bronchi. Thus, the processor
may identify the first branch is further in response to determining
that the first branch is located on a contra-lateral side of the
luminal network with respect to the target.
[0172] In certain embodiments, the set of instructions include
instructions to drive the instrument to a first location within the
luminal network. The first location may be a location identifiable
by the user during the medical procedure which can provide a known
location within each of the location sensor coordinate system and
the model coordinate system. For example, during a bronchoscopy
procedure, the first location may correspond to the patient's
carina. The carina may be identified within the model based on its
location at the branch between the main bronchi and the user may be
able to drive to the carina prior to the registration of the
location data. In this embodiment, the first and second branches
may correspond to main bronchi of the patient. The registration
between the location sensor coordinate system and the model
coordinate system may be further based on location data received
from the set of location sensors while the distal end of the
instrument is within a threshold distance from the first location.
By using the first location as a known point of reference between
the location coordinate system and the model coordinate system, the
number of permutations for the registration can be limited.
Additionally, the user instructions may include an instruction to
retract the instrument after touching the carina. This retraction
may be interpreted as an indication of the position of the carina,
which can be used as the first location during the registration
procedure.
D. Introduction to Weight-Based Registration of Location
Sensors.
[0173] As described above in connection with FIG. 15, certain
techniques for localization of a distal end of a medical instrument
may involve combining inputs from different sensors/sources to
determine the position of the distal end of the medical instrument.
These inputs can include a location sensor (e.g., an EM sensor) at
the distal end of the instrument, an image sensor (e.g., a camera)
at the distal end, and/or robot insertion data (e.g., robotic
command and kinematics data). In one example, three algorithm
modules (e.g., EM-based, robot-based, and image-based) can output
their respective estimated state data of the location of the distal
end of the instrument to a Sensor Fusion module (e.g., the
localization module 95 of FIG. 15) which combines the information
from the three algorithm modules and produces an output of the
navigation framework. In some implementations, the localization
algorithm can provide probabilities as to the current position of
the distal end of the medical instrument (e.g., which can be
defined by a segment ID and a depth/insertion within a
corresponding segment with reference to a model of a patient's
luminal network). One example of a model is a skeleton that can be
generated based on the centerlines of a luminal network. Model
location points may be defined along the skeleton, such that the
representation of the position of the distal end of the medical
instrument is along the centerline/skeleton of the corresponding
lumen. In addition, some implementations of a branch prediction
algorithm can provide probabilities as to which child lumen of the
current lumen the medical instrument is driving towards (e.g., a
probability for each child lumen that the medical instrument is
likely to enter the corresponding lumen).
[0174] In some implementations, a location sensor registration
algorithm is used to calculate a transformation between a sensor
coordinate system (e.g., EM sensor space) and a model coordinate
system (e.g., CT/skeleton space). Each of the location sensor
localization algorithm module and location sensor branch prediction
algorithm module can determine the registered pose of the distal
end of the medical instrument in the model coordinate system, which
can be used by each of the location sensor algorithm modules for
determining the algorithm output values (e.g., the current position
of the distal end of the medical instrument and the probability
that the medical instrument is likely to enter each of the child
lumens).
[0175] FIG. 24 is flowchart which illustrates an example method 900
operable by a surgical robotic system, or component(s) thereof, for
determining a registration between the sensor coordinate system and
the model coordinate system in accordance with aspects of this
disclosure. It is to be appreciated that the steps of method 900
illustrated in FIG. 24 may be performed by a processor of a
surgical robotic system. For convenience, the method 900 is
described as performed by the processor of the system.
[0176] The processor may be included as a part of a system,
including an instrument having a set of one or more location
sensors. The set of location sensors may be configured to generate
location data indicative of a position of the set of location
sensors in a location sensor coordinate system. The location
sensors may be located at or near a distal end of the instrument
(e.g., see FIG. 18), and thus, the location data may be indicative
of the location of the distal end of the instrument. The system may
further include a set of instrument manipulators configured to
control movement of the distal end of the instrument and at least
one computer-readable memory in communication with the processor
and having stored thereon a model of a luminal network of a
patient. The model may include a target within a model coordinate
system and a path to the target. The memory may further have stored
thereon computer-executable instructions to cause the set of
processors to perform the method 900.
[0177] The method 900 may begin at block 901. At block 902, the
processor receives location data from the set of location sensors
and receives state data indicative of a current state of the distal
end of the instrument. In certain implementations, the state data
may be generated by a Sensor Fusion module (e.g., the localization
module 95 of FIG. 15) based on a combination of information from
different algorithm modules (e.g., EM-based, robot-based, and
image-based).
[0178] In some implementations, the method 900 may include a
registration algorithm which can be used to compute a rigid
transform (e.g., the registration) that represents the homogenous
transformation between the sensor coordinate system of the location
sensor (e.g., based on the position of a field generator when the
location sensor comprises an EM sensor) and the model coordinate
system. The transformation can then be used to transform any pose
for the distal end of the medical instrument from the location
sensor coordinate system to the model coordinate system.
[0179] At block 904, the processor performs contra-lateral
registration and maintains a skeleton position history (also
referred to as a model position history) and a location sensor
position history. For example, the processor may perform
contra-lateral registration in accordance with the methods 500 and
550 described in connection with FIGS. 20A and 20B. In addition,
the processor may maintain the skeleton position history by storing
the state data and maintain the location sensor position history by
storing the location data. In some implementations, the skeleton
position history and the location sensor position history may be
formatted as point clouds representative of the position of the
distal end of the instrument over time.
[0180] The location sensor history point cloud and the
corresponding model history point cloud can be used as inputs to
determine the registration transformation. Depending on the
implementation, different techniques for determining the
registration can be used. For example, the registration can be
determined using: a Singular Value Decomposition (SVD) technique,
an iterative closed point (ICP) technique, or any other technique
which can determine the registration between two coordinate
systems.
[0181] At block 906, the processor determines whether a
pre-registration condition has been met. In some implementations,
determining whether the pre-registration condition been met may
involve determining whether sufficient data has been collected in
each of the skeleton position history and the location sensor
position history for registration. In some implementations, the
processor can determine that sufficient data has been collected in
response to one or more of the following conditions being
satisfied: the instrument is positioned, e.g., in the second
generation segment (or the third generation segment, etc.), the
instrument has been advanced at least a threshold distance (or at a
threshold velocity) into the second generation segment, and/or the
size (e.g., number of data points) of the skeleton position and
location sensor position histories is greater than a threshold size
(e.g., the size/amount of data of the skeleton position history
meets/exceeds a first threshold value, the size/amount of the data
of the location sensor position history meets/exceeds a second
threshold value, and/or the size/amount of the skeleton position
histories and location sensor position histories meets/exceeds a
third threshold value).
[0182] At block 908, the processor determines an initial
registration based on the skeleton position history and the
location sensor position history. The determination of the
registration can be performed, for example, as described in
connection with block 525 of FIG. 20A and/or block 570 of FIG. 20B.
Using the determined registration, the system can determine the
registered pose of the distal end of the medical instrument by
applying the registration to the location sensor data.
[0183] At block 910, the processor determines whether the inclusion
of an additional point from the location sensor history point cloud
into the registration results in an error that is greater than a
threshold error. The determination in block 910 may be performed
for each point within the location sensor history point cloud as
the instrument is advanced through the luminal network. In response
to the error being greater than the threshold error, the method 900
involves locking or keeping the registration at block 912 and
continuing with the procedure at block 916.
[0184] However, in response to the error being less than or equal
to the threshold error, the method 900 involves updating the
registration (or re-determining the registration) at block 914
based on the additional point from the location sensor history
point cloud. In some implementations, the processor can update the
registration using the point from the location sensor history point
cloud which results in an error that is less than or equal to the
threshold error in block 910.
[0185] For example, some user driving behaviors or tendencies, such
as, for example, hugging the wall of a lumen (e.g., skewing a
medical instrument toward the wall, contacting the wall, driving
the medical instrument away or removed from a the centerline of a
luminal passageway, and/or otherwise driving the medical instrument
along a path offset from the centerline of the luminal passageway)
or buckling of the medical instrument can cause a level of mismatch
between the registered location sensor points and the corresponding
points on the model. FIG. 25 illustrates an example in which sensor
location points and model location points are overlaid on the model
in the model coordinate system in accordance with aspects of this
disclosure. Specifically, in the image of FIG. 25, the sensor
location points 1002 and the model location points 1004 are
illustrated with respect to the model (e.g., a skeleton) 1006. The
illustrated sensor location points 1002 are transformed into the
model coordinate system based on the initial registration
determined in block 908, which in some examples can be completed
after the contra-lateral registration in block 902.
[0186] In order to improve the accuracy of the registration and the
robustness to sub-optimal driving behaviors such as hugging to the
airway wall, certain aspect of this disclosure relate to the use of
a weight-based registration after the contra-lateral step is
complete and the initial registration is calculated. Thus, when the
error determined in block 912 is greater than the threshold error,
the method 900 involves, at block 914, the processor updating the
initial registration. In some implementations, updating the initial
registration involves using the weight-based registration
techniques described in further detail below. As discussed below,
the weight-based registration can involve determining and assigning
different weights for the location sensor point and model points
used during registration. At block 916, the processor continues
with the procedure using the registration determined by the method
900. The method 900 may end at block 918.
E. Example Techniques for Determining Weights for Use in
Registration.
[0187] In certain implementations, the initial registration can be
modified (e.g., at block 914 of the method 900) by determining and
assigning different weights to corresponding sensor location points
and model location points and re-determining the registration using
the weights.
[0188] In certain implementations, the weights can be calculated
based on the distance between: i) the location sensor points 1002
transformed into the model coordinate system after the initial
registration is determined, and ii) the model location points 1004.
FIG. 25 illustrates the distance between the transformed location
sensor points 1002 and the model location points 1004.
[0189] In one or more implementations, each of the weights can be
set to a value between 0 and 1. There are a number of different
techniques which can be used by the processor to determine the
weights. In one implementation, the processor can determine or
assign the weights proportionally to the distance between the
location sensor points 1002 and the model location points 1004. For
example, the n.sup.th weight can be determined using the following
equation: w.sub.n=1/a.sup.distance.sup.n, where a can be a constant
in some implementations. In other implementations, a can be
correlated to the radius of the corresponding lumen (e.g., the
trachea or the airway in which the n.sup.th points are located).
FIG. 26 illustrates one example for determining weights
proportional to distance. Specifically, FIG. 26 includes a first
plot 1102 of the distance between the transformed sensor location
points and the model location points (sometimes referred to as the
skeleton points) and a second plot 1104 of the corresponding
weights.
[0190] In another implementation, the weight can be binary (e.g., 0
or 1). For example, the processor can determine the weights based
on a comparison of the distance to a distance threshold (e.g. 5
mm), wherein a weighting factor of 0 is assigned to a given point
(e.g., a sensor location point) if the distance between the sensor
location point and the model location points is greater than or
equal to 0.5 mm or another distance threshold, and wherein a
weighting factor of 1 is assigned to the given point if the
distance between the sensor location point and the model location
points is less than the distance threshold. The distance threshold
corresponds to a tolerance level for disparities between the sensor
location points and the corresponding model location points, and
may be set based on clinical requirements and/or user preferences
as two what level of disparity is deemed acceptable. FIG. 27
illustrates another example for determining binary weights based on
distance. Specifically, FIG. 27 includes a first plot 1202 of the
distance between the transformed sensor location points and the
model location points and a second plot 1204 of the corresponding
weights.
[0191] FIG. 28 illustrates yet another example for determining
binary weights based on distance in accordance with aspects of this
disclosure. For example, the processor can assign the weights by
sorting the points in each lumen based on the distance. A
percentage of the points in each lumen with the smallest distance
can be assigned a weight of 1, while the remaining points can be
assigned a weight of 0. This implementation is illustrated in FIG.
28 with a first set of points 1302 having a weight of 1 and a
second set of points 1304 having a weight of 0.
[0192] In some implementations, the processor can calculate the
weights based on distance once for the contra-lateral registration
points after the initial registration is determined. These weights
can be applied to the same points in subsequent cycles of
registration (see FIG. 24), while the processor can assign the
remaining points accumulated for the registration in further
generations (e.g., second and greater generations) a weight of
1.
[0193] In other implementations, rather than determining the
weights only once for the contra-lateral points, the processor can
repeatedly or regularly determine and update the weights as the
distal end of the medical instrument is advance into further
generations and the registration is updated. The processor can
determine the weights for registration points accumulated in
further generations as well. The processor can maintain a history
of the weights/distance determined for earlier points in memory,
and set a constraint on how much the weights can change as a result
of registrations calculated later on in the procedure.
[0194] In some implementations, the processor can adaptively
increase the weights proportional to the diameter of the lumens as
the medical instrument is advanced into the luminal network. For
points in the initial generations (where the diameter of a given
lumen is larger) the weights can be smaller, and for points in
further generations where the diameter of a given lumen is smaller,
the weight can be larger since there is a smaller chance of the
scope diverging from centerline path in a smaller diameter
lumen.
[0195] In certain implementations, rather than using the initial
registration and distance of transformed sensor location points to
the centerline of the model for determining the weights, the
processor can determine the weights by using the vision algorithm
and assessing a metric for centerline driving by tracking the
contours of the airways visible from image captured by the camera
of the instrument. The processor can also use the robot
articulation data as another input for identifying centerline
driving of the medical instrument in order to determine the weights
based on the distance of the location sensor points from the
centerline. For example, corresponding points where the user is
driving the distal end of the medical instrument closer to the
centerline can be assigned a larger weight, and points where the
distal end of the medical instrument is not facing the centerline
(hugging closer to the luminal wall) can be assigned a smaller
weight.
[0196] Aspects of this disclosure can improve the robustness of the
registration algorithm related to continuously registering sensor
location points to model points throughout the procedure. For
example, by weighting the location sensor points used in
determining the registration, the processor can improve the
accuracy of the registration by more heavily weighting points that
are located closer to the skeleton model, while reducing the
influence or effect of points that are further away from the
skeleton when determining or performing registration.
[0197] Aspects of this disclosure can also be applicable to other
techniques for registering two sets of 3D point clouds (e.g. EM
points and skeleton model points), including shape-sensing-based
and/or other sensor-based solutions.
3. Implementing Systems and Terminology
[0198] Implementations disclosed herein provide systems, methods
and apparatuses for the registration of location sensors to a model
coordinate system.
[0199] It should be noted that the terms "couple," "coupling,"
"coupled" or other variations of the word couple as used herein may
indicate either an indirect connection or a direct connection. For
example, if a first component is "coupled" to a second component,
the first component may be either indirectly connected to the
second component via another component or directly connected to the
second component.
[0200] The functions described herein may be stored as one or more
instructions on a processor-readable or computer-readable medium.
The term "computer-readable medium" refers to any available medium
that can be accessed by a computer or processor. By way of example,
and not limitation, such a medium may comprise random access memory
(RAM), read-only memory (ROM), electrically erasable programmable
read-only memory (EEPROM), flash memory, compact disc read-only
memory (CD-ROM) or other optical disk storage, magnetic disk
storage or other magnetic storage devices, or any other medium that
can be used to store desired program code in the form of
instructions or data structures and that can be accessed by a
computer. It should be noted that a computer-readable medium may be
tangible and non-transitory. As used herein, the term "code" may
refer to software, instructions, code or data that is/are
executable by a computing device or processor.
[0201] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is required for proper operation of the method
that is being described, the order and/or use of specific steps
and/or actions may be modified without departing from the scope of
the claims.
[0202] As used herein, the term "plurality" denotes two or more.
For example, a plurality of components indicates two or more
components. The term "determining" encompasses a wide variety of
actions and, therefore, "determining" can include calculating,
computing, processing, deriving, investigating, looking up (e.g.,
looking up in a table, a database or another data structure),
ascertaining and the like. Also, "determining" can include
receiving (e.g., receiving information), accessing (e.g., accessing
data in a memory) and the like. Also, "determining" can include
resolving, selecting, choosing, establishing and the like.
[0203] The phrase "based on" does not mean "based only on," unless
expressly specified otherwise. In other words, the phrase "based
on" describes both "based only on" and "based at least on."
[0204] The previous description of the disclosed implementations is
provided to enable any person skilled in the art to make or use the
present invention. Various modifications to these implementations
will be readily apparent to those skilled in the art, and the
generic principles defined herein may be applied to other
implementations without departing from the scope of the invention.
For example, it will be appreciated that one of ordinary skill in
the art will be able to employ a number corresponding alternative
and equivalent structural details, such as equivalent ways of
fastening, mounting, coupling, or engaging tool components,
equivalent mechanisms for producing particular actuation motions,
and equivalent mechanisms for delivering electrical energy. Thus,
the present invention is not intended to be limited to the
implementations shown herein but is to be accorded the widest scope
consistent with the principles and novel features disclosed
herein.
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