U.S. patent application number 12/429546 was filed with the patent office on 2009-11-12 for system and method for a medical procedure using computed tomography.
Invention is credited to Marcus Pfister, Norbert Strobel.
Application Number | 20090281452 12/429546 |
Document ID | / |
Family ID | 41257080 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090281452 |
Kind Code |
A1 |
Pfister; Marcus ; et
al. |
November 12, 2009 |
SYSTEM AND METHOD FOR A MEDICAL PROCEDURE USING COMPUTED
TOMOGRAPHY
Abstract
A system and method for planning and performing a percutaneous
medical procedure is described. A three dimensional data set of a
patient is registered with respect to a patient position and an
interventional apparatus, which may be a C-arm X-ray device. A
target within the patient is identified in the image data, and a
skin entry point chosen for planning the procedure. The image data
set is processed so as to compute a two dimensional fluoroscopic
overlay image upon which the target and the skin entry point are
displayed. The angulation of the volumetric representation of the
C-arm is controlled so as to plan the guiding path for an
interventional device, and the planning attempts to achieve one of
a bull's eye orientation or a generalized bull's orientation. The
interventional device is aligned with the guiding axis to perform
the procedure, which may be monitored using X-ray progression
views.
Inventors: |
Pfister; Marcus;
(Bubenreuth, DE) ; Strobel; Norbert; (Heroldsbach,
DE) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Family ID: |
41257080 |
Appl. No.: |
12/429546 |
Filed: |
April 24, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61049803 |
May 2, 2008 |
|
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|
Current U.S.
Class: |
600/567 ;
378/206 |
Current CPC
Class: |
A61B 2090/364 20160201;
A61B 2090/376 20160201; A61B 90/11 20160201; A61B 90/13 20160201;
A61N 2005/1061 20130101; A61B 6/5229 20130101; A61B 6/12 20130101;
A61B 2034/107 20160201; A61B 6/4441 20130101 |
Class at
Publication: |
600/567 ;
378/206 |
International
Class: |
A61B 10/02 20060101
A61B010/02; A61B 6/08 20060101 A61B006/08 |
Claims
1. A method for planning a percutaneous medical procedure, the
method comprising: obtaining three-dimensional image data of a
patient; orienting a representation of the patient, or the patient,
with respect to a trackable patient support table of an
interventional apparatus; registering the three-dimensional image
data with respect to the patient; and planning the percutaneous
medical procedure using the three dimensional image data, wherein
an intervention path is planned so that an intervention device is
alignable along a guiding axis passing through a skin entry point
and a target and one of a bull's eye or a generalized bull's eye
image is obtained in an X-ray projection image view.
2. The method of claim 1 wherein the interventional apparatus is a
C-arm X-ray apparatus.
3. The method of claim 1, wherein the interventional device is a
biopsy needle.
4. The method of claim 1, wherein a bull's eye view is obtained
when the skin entry point and the target are aligned along the
central axis of the interventional apparatus.
5. The method of claim 4, wherein the interventional device is
aligned with the optical axis using one of a laser pointer or a
plurality of laser fan beams.
6. The method of claim 5, wherein the aligned device is maintained
in position using a mechanical fixture.
7. The method of claim 1, wherein a generalized bull's eye view is
obtained when the interventional path does not lie along an optical
axis of the interventional apparatus.
8. The method of claim 7, wherein, when a generalized bull's eye
view is obtained, re-reorienting the patient to plan an
intervention path lying closer to the interventional apparatus
optical axis.
9. The method of claim 8, wherein the step of re-orienting includes
re-positioning the patient support table.
10. The method of claim 1, wherein a first planned angulation of
the interventional apparatus is associated with the interventional
path.
11. The method of claim 1, further comprising: comparing a
volumetric location of the interventional apparatus for a first
planned angulation of the interventional apparatus with a
volumetric location of the patient, and the patient table and
determining that a collision does not result.
12. The method of claim 1, wherein a second planned angulation of
the interventional apparatus is associated with a progression view
of the interventional path.
13. The method of claim 1, wherein a second planned angulation of
the interventional axis is associated with a progression view of
the interventional path and the target.
14. The method of claim 1, wherein orienting a representation of
the patient comprises: generating two-dimensional image data from
the three dimensional image data of the patient and registering the
coordinates of the patient with respect to coordinates of
interventional apparatus.
15. The method of claim 14, further comprising: positioning the
patient so that the patient coincides with a registered skin
surface image, at least within the field of view of an image to be
obtained by the interventional apparatus.
16. The method of claim 1, further comprising: positioning a tip of
the interventional device such that a skin penetration is made at
the skin entry point, and an axis of the interventional device
passes through the target.
17. The method of claim 1, further comprising: performing the
planned medical procedure.
18. The method of claim 17, wherein the step of performing the
planned interventional procedure further comprises: advancing the
intervention device along the guiding axis through the skin entry
point; adjusting an angulation of the interventional apparatus so
as to obtain a progression image of the interventional device; and
determining that the interventional device is aligned along the
guiding axis; or, determining that the interventional device is not
aligned along the guiding axis and correcting an alignment of the
interventional device.
19. The method of claim 18, further comprising: repeating the steps
of advancing, adjusting and determining until a tip of the
interventional device is positioned in a planned position with
respect to the target.
20. The method of claim 18, further comprising: using the
interventional device to perform a procedure on the target.
21. The method of claim 1, wherein the target is identified in the
three-dimensional image data.
22. The method of claim 21, wherein the target is displayed as a
synthetic image in a two-dimensional image derived from the
three-dimensional image data.
23. The method of claim 21, wherein the target is displayed as a
synthetic image in a fluoroscopic image obtained by the
interventional apparatus.
24. The method of claim 1, wherein an endoscopic view along the
guiding path is produced from the three-dimensional image data.
25. A computer program product for planning a medical procedure,
the product being stored on a computer readable medium, comprising:
instructions for configuring a computer to: accept
three-dimensional image data of a patient; register the three
dimensional data image with respect to the patient; produce images
suitable for planning a guiding path between a skin entry point and
a target in the patient; determine the axis of the guiding path and
a corresponding angulation of an interventional apparatus having
imaging capability; determine the volumetric relationship between
the interventional apparatus when oriented at the angulation with
respect to a patient support; determine whether there is an
collision between the interventional apparatus and the patient
support.
26. The computer program product of claim 25, wherein, when the
guiding path does not lie on an optical axis of the interventional
apparatus, re-determining re-planning the procedure by changing at
least one of the angulation or the position of the patient support
table to bring the guiding path into closer angular alignment with
the optical axis.
27. The computer program of claim 25, wherein a synthetic image of
the target is superimposed on an image of the images used for
planning.
28. The computer program of claim 25, wherein an icon representing
a skin entry point is superimposed on the image.
29. The computer program of claim 28, wherein when the planned
angulation of the interventional apparatus is adjusted, a relative
position of the icon and the synthetic image of the target is
compared so as to determine whether a bull's eye or generalized
bull's eye alignment has been achieved.
30. The computer program of claim 29, wherein an operator input
device controls the computed angulation of the interventional
apparatus, and the corresponding image.
Description
[0001] This application claims the benefit of U.S. provisional
application Ser. No. 61/049,803, filed on May 2, 2008, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present application may relate to a system and method
for performing percutaneous medical procedures using imaging
modalities for instrument alignment and guidance.
BACKGROUND
[0003] With modern angiography X-ray systems (such as Axiom Artis
made by Siemens, Munich, Germany), not only can 2-dimensional
radiographic images be obtained but also, by rotation of the C-arm
around the patient, 3-dimensional (3D), computed tomographic
(CT)-like images can also be attained. These 3D data sets can be
registered anatomically correctly to the 2D radiographic images
(2D/3D registration) for purposes of, for example, intervention
planning or intervention navigation. In particular, percutaneous
punctures, for obtaining biopsies or administering treatment can be
planned on these data sets. For all systems involving the exposure
of patients and personnel to ionizing radiation, the total
radiation dosage is a concern and should be held to the lowest
value consistent with the medical benefit.
[0004] German Patent application DE 10200729119, filed on Jul. 25,
2007, and published as DE 10 2007 029 199 on Jan. 2, 2009, having a
common inventor, entitled "Method for Aligning a Target Guidance
System for a Puncture, and an X-ray Angiographic System" describes
a method of orienting a biopsy needle using a laser aligned along
the planned puncture path. This application is incorporated herein
by reference. The aiming of the laser includes manual alignments
(such as the table position), in order to achieve a match between
the needle and the planned path. This is attained by moving the
C-arm and/or the patient support table, or both, so that certain
markings on a display screen match. The needle can be aligned
without further irradiation of the patient (and doctor); however,
the approach is limited to the positions that are feasible for
orientation of the C-arm or the patient support table, which may
also limit the orientation of the central (optical) axis of the
radiation beam with respect to the patient.
[0005] U.S. patent application Ser. No. 12/329,657, filed on Dec.
8, 2008, having a common inventor, and entitled "X-ray device and
Workflow for Guiding Percutaneous Procedures," describes a method
which permits a general alignment of the needle with a planned
puncture path (virtual path). This application is incorporated
herein by reference. The C-arm is positioned in such a way that the
puncture target and the primary penetration point of the body,
which together define a puncture path, are projected onto the X-ray
detector so as to coincide (known as a "generalized bulls-eye
view"). This method generally results in fewer limitations on the
orientations of the radiation beam, and manual movement of the
patient support table is not needed. However the method requires
the alignment under X-radiation of the patient (and the
doctor).
SUMMARY
[0006] A method planning or performing a percutaneous medical
procedure is disclosed, the method including the steps of obtaining
three-dimensional image data of a patient; and orienting a
representation of the patient, or the patient, on a patient support
table of an interventional apparatus. The three-dimensional image
data is registered with respect to the coordinate system of the
oriented patient and a percutaneous medical procedure is planned
using the three dimensional image data. The planned path is such
that a guiding axis for an interventional device passes through a
skin entry point and a target. The computed angulation of the
interventional apparatus is adjusted such that one of a bull's eye
or a generalized bull's eye image is obtained in a projection
view.
[0007] In an aspect, a computer program product includes
instructions for configuring a computer to accept three-dimensional
image data of a patient and register the three dimensional data
image with respect to the patient. Images suitable for planning a
guiding path between a skin entry point and a target in the patient
are produced, and a planned path is one whose axis passes through
the skin entry point and the target. The selected angulation of the
planned path is one which meets one of a bull's eye or generalized
bull's eye criterion. For the selected angulation, relation between
a volumetric representation of the interventional apparatus and the
patient support table is computed so as to determine whether there
would be a collision between the interventional apparatus and the
patient support table.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram showing the component equipment of
a treatment unit for planning and performing a percutaneous medical
procedure;
[0009] FIG. 2 illustrates schematically the orientation of a skin
entry point and a target in a patient body on a radiograph for (A)
a bull's eye view; (B) a generalized bull's eye view; and, (C) no
alignment, where the representations of the skin entry point and
the target are shown in a relative size for clarity in
illustration; and
[0010] FIG. 3 is a workflow for a method of planning and performing
the percutaneous procedure
DETAILED DESCRIPTION
[0011] Exemplary embodiments may be better understood with
reference to the drawings. In the interest of clarity, not all the
routine features of the implementations described herein are
described. It will of course be appreciated that in the development
of any such actual implementation, numerous implementation-specific
decisions must be made to achieve a developer's specific goals,
such as compliance with system and business related constraints,
medical protocols and regulatory requirements, and that these
constraints will vary from one implementation to another.
[0012] A system for planning or performing a percutaneous procedure
is disclosed. The system may comprise an imaging system having a
movable arm, an X-ray source and an X-ray detector; and, a display
and a system controller connected to and in communication with the
imaging system and display, and include a machine-readable storage
medium encoded with a computer program code such that, when the
computer program code is executed by a processor, the processor
performs a method as described herein.
[0013] The examples of diseases, syndromes, conditions, and the
like, and the types of examination and treatment protocols
described herein are by way of example, and are not meant to
suggest that the method and apparatus is limited to those named, or
the equivalents thereof. As the medical arts are continually
advancing, the use of the methods and apparatus described herein
may be expected to encompass a broader scope in the diagnosis and
treatment of patients.
[0014] The following terms are used herein: A "patient
3-dimensional image data set" is a three dimensional numerical
array whose elements hold the values of specific physical
properties at small volumes in space inside the patient's body;
each volume is known as a "voxel" and may be considered to be
comparable to a "pixel" in a 2-dimensional image.
[0015] A "multiplanar reformation image (MPR)" is a planar
cross-section of the patient 3-dimensional image data set generated
by cutting through the three-dimensional data set at some
orientation (e.g., axial, coronal, sagittal, or oblique), which may
be a slice of CT or CT-like data.
[0016] A "fluoroscopic image" or "radiographic image" is a
two-dimensional x-ray projection image showing internal tissues of
a region of the body. This image may be either live or synthesized
(rendered) from previously obtained three dimensional voxel data.
Two-dimensional representations of the 3D volume data set generated
using volume rendering techniques may also be referred to as
fluoroscopy overlay images. Fluoroscopy overlay images may include
graphical representations of instrument trajectories or of
instruments together with the surrounding anatomy.
[0017] A "live fluoroscopic image" is a sequence of x-ray images
taken successively showing live movement of internal tissues of a
region of the body. A "combined image" is an image in which an
X-ray image is combined with a 2D representation of a 3D data set
computed using volume rendering techniques. Such images may also be
overlaid with icons or other representations of a target, a skin
entry point, or a planned or estimated position of an
interventional device.
[0018] "Registering" or "co-registration" means aligning an X-ray
image, such as a fluoroscopic image, with the patient 3-dimensional
image data set such that associated features of the X-ray image and
a two-dimensional overlay image generated from the previously
obtained patient 3-dimensional image data set appear at the same
location on a display when the X-ray image and the overlay image
are shown together. Registration can be point-based or gray-level
based. In point-based registration, a transform is applied to the
3-dimensional image data set such that points in the resulting
overlay image line up with their counterparts in the x-ray image
and meeting a metric, which may be analytic or visual. Gray-level
based registration techniques determine the transform not by
minimizing the distance between associated points in the overlay
image and X-ray image, but by minimizing an error metric based on
the resulting overlay image gray levels and the X-ray image gray
levels.
[0019] "Interventional device" or "Interventional Instrument"
refers to any object which may pierce tissue of a patient, a
non-limiting listing of which include needles and other biopsy
devices, screws, implants, cannula, endoscopes, and anything else
that can be inserted into a patient's body percutaneously.
[0020] An "Interventional apparatus refers to an imaging modality
such as a C-arm X-ray device for obtaining internal image data of a
patient, or other device performing a similar function.
[0021] A "skin entry point" is the position on a patient's skin at
which an interventional device is inserted. "Skin entry point data"
is data representative of the skin entry point within the patient
3-dimensional image data set or within two X-ray views taken under
different view orientations using a triangulation technique.
[0022] A "target" or "target point" is a point within the body of a
patient that is the object of a percutaneous procedure.
[0023] An "interventional path" is a line between the skin entry
point and the target point and the "target."
[0024] "Instrument trajectory" is a desired motion of the
instrument along the interventional path.
[0025] A "progression view" is an x-ray image taken at an oblique
angle with respect to a line joining the skin entry point and the
target.
[0026] A "collimator" is a device used to narrow the radiation
field to a size needed for the examination at hand. For this
purpose, the collimator may have sets of lead plates providing
either a round or a square-shaped radiation field. The aperture of
the collimator may be adjusted either automatically or manually,
depending on the system. Many collimators are axially symmetric and
are oriented so that the axis of symmetry of the collimator is
aligned with the optical axis of the X-ray system.
[0027] An "optical axis" (or "central axis") of a C-arm X-ray
device is defined by a line orthogonal to a detector and passing
through the center of radiation of an X-ray source. The optical
axis is usually positioned so as to pass through a central point of
the detector, and is aligned with the C-arm X-ray device's central
ray of the X-ray radiation cone.
[0028] A "Bull's Eye View" is an x-ray view under which a target
point and another point along the instrument trajectory are
projected onto each other. The other point along the instrument
trajectory may be the skin entry point. The view direction of the
imaging modality can be visualized using a graphical overlay in
which the target point and skin entry point, forward-projected from
3-dimensions to 2-dimensions, are displayed as individual circles.
If the Bull's Eye View has been reached, these two circles are
projected at the same 2-dimensional position (i.e., they appear
concentrically aligned). Further the image skin entry point and the
target point lie on the optical axis of the X-ray device.
[0029] A "Generalized Bull's Eye View" has the same properties as a
"Bulls Eye View"; however, a ray different from the central ray of
the x-ray cone is used to project target and another point along
the instrument trajectory onto each other. As a consequence, the
concentrically aligned circles are not located on the optical axis
of the X-ray device. In an aspect, where a central point of a flat
panel display may be considered to represent the optical axis of
the X-ray device, the bull's eye view places the aligned circles at
the central point, whereas the generalized bulls-eye view places
the aligned circles at any other point on the flat panel
detector.
[0030] The terms "bulls-eye" view and "generalized bulls-eye" view
are conceptually adopted from the sport of target shooting, where a
target having concentric rings is placed at a distance and a
firearm aimed at the central ring and discharged. The central,
smallest ring, which is typically a solid circle, is known as the
"bull's eye". Aiming the firearm, whether using "iron sights" or a
telescopic sight, includes the steps of generally pointing the
firearm at the target, and aligning longitudinally displaced front
and rear sights of the firearm so that the sights and the bulls eye
of the target coincide. This is considered to be the alignment that
will place the bullet in the central ring. Where a telescopic sight
is used, a reticle or crosshair is provided to be aligned with the
target bulls eye. It might also be visualized as a
"down-the-gunbarrel view," or "down-the-barrel view".
[0031] The analogy is not so stretched, as the system and method
described herein may be used, for example, with a biopsy gun. In
the present context, aiming refers to an angulation of the C-arm of
the X-ray device such that where a needle appears as a circle in a
radiographic image, rather than as a line. That is, a near end of
an object such as a needle, and the far end of the object of the
object appear to be collapsed into a circle when projected onto the
flat panel detector using the radiated X-rays, or in a computer
simulation of the same orientation. Where a target, such as a
bodily structure or organ to be treated or investigated, such as by
biopsy, also coincides with the circle, bulls eye aiming has been
performed. When planning is performed on a C-arm X-ray device, for
example, this also means that a long axis of the needle is aligned
along the optical axis of the C-arm device, else the bulls-eye
circle will not be obtained. This circumstance also places the
bull's eye in the center of the flat panel detector, providing that
the flat-panel detector is disposed so as to be orthogonal to the
optical axis and symmetrically arranged with respect thereto.
[0032] The bull's eye situation may be optimum from the viewpoint
of minimizing the radiation exposure of the patient, as the
fluoroscopic images that may be needed during an alignment
procedure for the needle may be obtained with the optimum
adjustment of the collimator. Such collimator devices are typically
axially symmetric with the X-ray beam axis.
[0033] In a "Generalized Bulls Eye View" the C-arm has an
angulation direction such that the start point of an object, such
as a needle, is projected onto its end point on a 2D detector.
However, the position at which the X-ray through object start point
and object end point hits the detector can be anywhere on the
detector. In this circumstance, the entry point and the target are
not on the optical axis of the X-ray system.
[0034] A 3D (volumetric) image data set of a patient may be
acquired using a C-arm X-ray device, a computerized tomographic
unit (CT), a Magnetic Resonance Imager (MRI), or any other suitable
imaging modality. This 3D data may be obtained contemporaneously
with the planning and execution of a medical procedure, or at an
earlier time.
[0035] In an example, a C-arm X-ray device 10 as shown in FIG. 1
may be representative of imaging modalities which may be used in
the system and method described herein. Other imaging modalities
such a MRI, ultrasound (US), CT, and the like may be used for all
or part of the procedure.
[0036] A C-arm 26 has a radiation source 11 and a detector 14
attached thereto, and the C-arm may be moved in arcuate or other
three-dimensional paths, around, or partially around the patient
20. The patient may be positioned on a patient support table 25. A
collimator (not shown) may be associated with the radiation source
11 so as to limit the angular field and direction of the radiation
6.
[0037] The C-arm X-ray device 10 may be rotated such that a
sequence of projection X-ray images is obtained by an X-ray
detector 14, which may be a flat panel solid state two-dimensional
detector positioned on an opposite side of the patient 20 from the
X-ray source 11 so as to obtain data for 3-dimensional imaging and
produce CT-like data.
[0038] The X-ray detector 14 may be amorphous Silicon (a-Si),
amorphous Selenium (a-Se), PbI2, CdTe or HgI2 detectors, or the
like, using direct detection or TFT technology, or indirect
detectors as is known in the art, or may be subsequently developed,
to provide high resolution, high-dynamic-range essentially
real-time X-ray detection.
[0039] A C-arm X-ray device does not completely surround a patient,
as does a conventional CT apparatus. Thus, the C-arm X-ray device
may provide more convenient access to the patient during
interventional treatment, without moving the patient with respect
to the imaging modality, or disconnecting monitoring and therapy
equipment. The CT-like data and corresponding fluoroscopic data may
be obtained with the same device. Images can be reconstructed so as
to form CT-like voxel data sets, and segmented by any technique of
image or data processing for realizing computed tomographic (CT)
images and representations thereof.
[0040] The C-arm X-ray unit and the associated image processing may
be of the type described in US PG-Pub Application US2006/0120507,
entitled "Angiographic X-ray Diagnostic Device for Rotational
Angiography", filed on Nov. 21, 2005, which is incorporated herein
by reference.
[0041] A patient support table 25 may be used for some or all of
the examination steps and thus may transfer the patient 20 between
various sensors or otherwise position the patient 20. The patient
support table 25 is trackable, using motion or position sensors, so
that the table may be located and relocated with respect to the
coordinate system of the C-arm 10. The motion sensor 15 may
transmit data to the image processor 38 through a wired connection
or in wireless form. The function of eliminating motion artifacts
may include motions that are due to breathing. For example, a chest
belt using suitable sensors may be used to ascertain the breathing
amplitude and frequency, and initiate corrective calculations in
the image processor 38 or control the timing of the X-ray images
using the X-ray controller 28 so that that motion artifacts are
mitigated. A variety of video displays 33, which may be flat panel
displays, may be provided to present images and data for
manipulation and analysis.
[0042] A computer device 70 may be a notebook PC computer, or other
processing device with which the demographic, history, diagnosis or
therapy data of the patient can be recorded, called up and sent to
and from the medical information management system of the hospital
over a local area network (LAN) or the like. The computer device 70
may be provided with a data interface for retrieving data from an
HMO (health maintenance organization), health insurance smart card,
or other patient data base, and may be connected to the remainder
of the therapy suite by a wired or a wireless connection. A user
input device 71, such as a keyboard, computer display device, and
mouse, may be provided for manual input and control. The computer
device may also perform signal and data processing operations that
have been described herein as being performed by separate computer
devices, and the allocation of system functions to one or more
computers is a matter of design choice, which may be expected in
different embodiments.
[0043] Additional, different, or fewer devices may be provided in a
therapy suite. The devices and functions shown are representative,
but not inclusive. The individual units, devices, or functions may
communicate with each other over cables, wires, or in a wireless
manner.
[0044] FIG. 2A shows a schematic plan view of an radiographic image
that would be produced where a bull's eye view orientation of a
target 200 and an interventional instrument, which may be a needle
250 is achieved. The image area 300 produced by, for example X-ray
detector 14, receiving radiation emitted by radiation source 11 is
centered so that the central point 350 of the image area 300 lies
on, and is perpendicular to the optical axis of the C-arm device
10. That is, the radiation source 11 and the X-ray detector are
mounted to the C-arm 26 and disposed such that a central ray of the
emitted X-radiation is aligned with and passes through the needle
250 and the target 200. The target 200 is representative of the
internal location in the patient 20 towards which the needle 250
would be advanced during the interventional procedure. The target
may be visualized in the radiographic image taken by the X-ray
device, or be synthesized using the previously acquired voxel data
for the patient. Similarly, the position of the needle 250 on the
central axis may be computed and displayed on the synthesized image
without emitting radiation. Combinations of synthesis and real-time
radiographs (fluoroscopy) may also be used.
[0045] Where a bull's eye alignment is achieved, a symmetrical
collimator may be used to minimize the angular width of the
radiation field 6 needed to obtain further radiographic images. A
laser pointer, or fan beams whose sources may be mounted to the
detector 14 may be used to align the needle 250 with the
interventional apparatus optical axis.
[0046] FIG. 2B illustrates a situation where the alignment
synthetic image of the needle 250 with the target 200 (whether a
synthesized target image or real-time radiograph) is displaced from
the central point 350 of the image. This is a generalized bull's
eye view. That is, a synthesized image of a needle 250 may be
aligned so as to point towards the target 200; however the long
axis of the needle 250 does not coincide with the optical axis of
the C-arm device 10. In this circumstance the needle may be guided
or aligned by a mechanical fixture, as the laser pointer approach
was intended to be used along the optical axis of the imaging
modality. In order to position the needle 250 so that the skin
entry point and the target 200 are along the axis of the needle
250, X-ray radiation may be needed so that the long axis of the
needle can be aligned. So, for a generalized bull's eye view, the
final alignment of the needle 250 is generally done under X-ray
guidance. As the area to be imaged is off of the optical axis of
the X-ray device 10, a collimator may have to be adjusted to permit
a wider cone angle of emitted radiation, particularly if the
collimator is limited to symmetrical x-ray beams.
[0047] FIG. 2C shows a situation where the needle position is
neither a bull's eye view nor a generalized bull's eye view. In
this situation, the planning process has not resulted in a
satisfactory solution. The planning process may be continued,
however other criteria may have to be changed, including, for
example, the position of the patient 20 on the patient support
table 25.
[0048] The adjustment of the needle 250 under radiation conditions
requires additional safety precautions, and the doctor may use
tongs or other holding devices to manipulate the needle 250 while
remaining outside of the direct radiation field.
[0049] The sensor portions of the therapy unit may be located in a
therapy room. Some of, or all of, the signal and data processing
and data display may also be located in the therapy room; however,
some of, or all of, the equipment and functionality not directly
associated with the sensing of the patient and the imaging modality
data sensors, may be remotely located. Such remote location of
portions of the equipment may be facilitated by high-speed data
communications on local-area networks, wide-area networks, or the
Internet. The therapy unit may thus be located remotely from the
specialists making the diagnosis and for determining the
appropriate course of treatment. Of course, the specialists may
also be present with the patient in the treatment room.
[0050] The 3-dimensional image data set used to identify the target
or to plan and monitor the procedure may be obtained using a
variety of known image generating systems in which typical targets
(e.g., tumors) can be seen clearly. Examples of such systems
include magnetic resonance imaging (MRI), Positron emission
tomography (PET), computer tomography (CT), and C-arm X-ray. If the
target is visible using 2D X-ray imaging, the target may be
localized using multiple x-ray views and triangulation techniques.
The 3-dimensional image data set may be obtained by taking a
plurality of X-ray images acquired under different view directions
by the C-arm X-ray device.
[0051] Where the 3D image data set is obtained by other than the
C-arm X-ray device, images obtained by the C-arm X-ray device and a
3D image data set obtained by another imaging modality may be
registered by any of the known registration methods, or by
registration methods which may be developed in the future. When the
C-arm X-ray device has been used to obtain the 3D data set, a 2D
radiographic image may be computed by, for example, by a maximum
projection intensity algorithm (MIP) or any other volume rendering
technique using the 3D data set as the source data. When the same
system has been used for both 2D and 3D imaging, the fluoroscopic
images and rendered projections are intrinsically registered. The
registration step ensures that the fluoroscopic (X-ray) images of
the patient obtained using the C-arm device to be used for the
procedure match the images of the patient constructed from the
3-dimensional data set. This enables instrument positioning using
information on target position obtained from the 3-dimensional data
set.
[0052] The C-arm X-ray apparatus may be fitted with a collision
control system so as to maintain a relationship of the physical
aspects of the C-arm X-ray device with respect to the patient, the
attending staff, ancillary equipment and the like. This collision
avoidance system may use any of a variety of sensors, which may be
acoustic, optical or electromagnetic, as well as motion and
distance sensors attached to or integrated with the X-ray
apparatus. Since the motion of the C-arm may be controlled
robotically, the C-arm may be fitted with sensors so that the
spatial location of the C-arm with respect to the laboratory
coordinate system, and to other devices located within the
laboratory coordinate system may be determined so as to plan or
execute a motion and to predict or avoid interference
("collisions").
[0053] The planned orientation of the X-ray apparatus and the
patient, including any motion of the patient support table may be
simulated by manipulating the reconstruction of the 3D and 2D image
data during the planning of the procedure. In this procedure, the
orientation of the C-arm is changed analytically and images are
reconstructed from the image data base so as to represent data
obtained from the particular angulation selected. Without moving
the actual equipment, the equipment motions may thus be simulated
within the known working environment so as to enable visualizing of
the procedure. In this manner, it may be determined if the
radiation (optical) axis of the C-arm X-ray device can be brought
into an orientation such that, based on a "bulls-eye" view, a laser
may be used to define the virtual path of the intervention device
(e.g., biopsy needle), without a collision occurring, or exceeding
any other equipment capability.
[0054] Alternatively, the same procedure and computer programs may
be used to determining whether the C-arm X-ray device may be
oriented so that the C-arm may be generally oriented so as to
project the virtual path onto the detector in a "generalized bulls
eye" view. This circumstance may be more efficient in terms of the
number of procedural steps required, but may expose the patient and
physician to higher radiation doses.
[0055] If the path cannot be planned so as achieve one of the
"bull's eye" or "generalized bull's eye" orientations as described
above, the path and angulation of the C-arm needs to be re-planned.
This re-planning may be so as to reorient the planned
interventional device path so as to use the laser orientation, or
the generalized bull's eye view. A generalized bull's eye view may
also be re-planned to bring the orientation of the interventional
path into better alignment with the optical axis, or to achieve a
bull's eye view. The re-planning can be performed as described
above, using a display of the 3D and 2D data and a graphical user
interface, or by the use of a device configured such that it may be
tracked on the skin surface of the patient by the
location/collision-avoidance system, or by a device specific
tracking system.
[0056] Once the procedure path has been planned, including
identifying the puncture location on the patient body, and the
orientation of the puncture needle, the doctor aligns the puncture
needle. Where the C-arm X-ray device can be aligned so that
radiation central axis (optical axis) may be such that the optical
axis passes through the puncture location and the internal target
location, a laser may be used to align the puncture needle with the
virtual path of the planned procedure. Using a laser alignment
apparatus and method may not require additional X-radiation during
the alignment step. Where the generalized bull's eye orientation is
used for the orientation, the alignment of the interventional
device may use X-radiation.
[0057] The progress of the procedure may be monitored by one of
virtual images, derived from the motion sensors and position
sensors previously described, or by obtaining progression view
X-ray images at periodic intervals. A combination of the two
techniques may be used so as, to conform to the doctor's experience
in obtaining the required level of precision in guidance of the
interventional device.
[0058] In an aspect, the process of aligning a needle along the
interventional path selected for the procedure, or re-planning the
path, may track a skin entry point (puncture point) using a
position sensor which may be placed on the patient's skin. The
position sensor, which may be optical or electromagnetic, may be
secured to, or integrated into, a device that is capable of
determining both the location and the direction of a vector aligned
with the interventional instrument. If this position sensor is
moved on the surface of the skin, an entry point can identified
with the position of the position sensor, and the entry point
re-determined with respect to a previously established target
(usually within the body) until a satisfactory interventional plan
has been made. During the re-planning stage, the virtual needle
path may be plotted in the 3 D volume or with respect to a
fluoroscopic overlay image derived from the 3 D data set using
volume rendering techniques.
[0059] Once a suitable needle guidance path has been found and the
entry point thus determined then, for instance, one can make a
marking on the skin for use in making the puncture during the
procedure (such as a color marking, optionally combined with
contrast agent injection, a small puncture, or the like). If the
instrument is a puncture guide needle, that the needle can be
inserted into the skin surface (after local anesthesia) and thus
fixed in position.
[0060] A variety of positioning devices may be used such as a
SeeStar (available from RADI Medical Systems AB, Upplsala, Sweden),
a flexible securing arm with mounting provisions for instrument
guidance (a guide sleeve, instrument securing or fastening device),
or the like. These devices may be robotically controllable. With
such a robotic device, the puncture direction may be defined
without touching the patient. The SeeStar device is an instrument
guide that produces an elongated artifact in an X-ray image. This
elongated artifact indicates the trajectory of an instrument
inserted through the SeeStar, and thus one can determine whether
the selected trajectory will intersect the target as desired. An
elongated radio-opaque object may also be used to represent the
needle during planning, including the orientation of a locating
fixture.
[0061] Once the needle path direction is fixed, one can introduce
the instrument into the patient. During this process, care would be
taken so that the position of the patient did not change and that
the puncture is made during the same respiratory phase used to
determine the guidance path. In another aspect, radio-opaque
markers may be temporarily affixed to the patient throughout the
process, so that a radiograph can quickly confirm the correct
positioning.
[0062] In an alternative, a hand guided device such as a biopsy gun
may be tracked by devices similar to those previously described,
and the guidance path of the intervention displayed on the
previously obtained images. If the orientation of the biopsy gun is
determined to be sufficiently well positioned with respect to the
target, then the gun can be activated to obtain a biopsy sample.
Such hand guided devices may be designed and constructed so as to
be powered by batteries contained in the device so that power cords
may be avoided and the maneuvering of the device in a congested
area simplified
[0063] In another aspect, an ultrasound device, whose location and
orientation can be determined, e.g., by localizing a guide sleeve
attached to it, may be used to orient a needle or other
interventional device. In this case, the guidance path of the
needle and the skin entry point can also be displayed in the
ultrasound images. Moreover, the position and orientation of the
guide sleeve may be tracked during the procedure and an updated
virtual image may be displayed showing the progress of the needle
with respect to the planned needle path.
[0064] The planning process for determining the puncture location
and the orientation of the guidance path so as to reach the target
may use the 3D data previously obtained and projected in a
forward-looking ("endoscopic") view so as to enable visualization
of the internal bodily tissues along the path of the planned
intervention; that is, the view is along the virtual path to the
target. Further, other views from the 3D data set may involve
segmenting the image so as to, for example, remove the soft tissue,
while leaving other bodily parts such as bones and blood vessels in
place. This assists in determining if the planned interventional
path will encounter obstacles such as bone, or if the
interventional path intersects with blood vessels or the like.
[0065] An analogous 3D data set could be created with an ultrasound
head that is movably mounted and then tracked with respect to the
securing arm of a guiding device. In an aspect, a 2D ultrasonic
(US) transducer, producing a forward-looking view may also be used
as a planning tool. Both the target and the direction of the
percutaneous intervention can be determined. If the orientation of
the US transducer and the C-arm are recorded with reference to each
other, the US path planning information can be communicated to the
3D C-arm CT data set so as to facilitate aligning the C arm.
[0066] If the "generalized bulls-eye view" is used for instrument
guidance, the projection of the skin entry point and "target" may
not be in the central region of the detector but in some outer
region that cannot be shielded by a central collimator. This may be
mitigated by movement of the table on which the patient is
positioned. The table may be moved such that the "generalized
bulls-eye view" extends through the central collimation opening.
Further, if the table can be moved such that the "generalized bulls
eye view" coincides with the optical axis of the C-arch, then the
conventional "bulls-eye view" orientation will have been reached.
In this situation laser guidance can be used. However, where the
"generalized bulls-eye view" and the optical axis of the C-arch are
not in agreement, then the instrument may be aligned using
fluoroscopy; this results in additional X-ray exposure. The
"bulls-eye view" and the "generalized bulls-eye view" become the
same view when the C-arm and the table have been oriented such that
the planned instrument trajectory in the patient extends through
the isocenter of the C-arm.
[0067] The C-arm device may have a collimator capable of
automatic/dynamic collimation around the planned instrument path,
or the tracked path, where the instrument path is tracked so as to
reduce the area subject to radiation during each step of the
procedure. Depending on the specific equipment configuration, such
collimation may be restricted to symmetry about the optical axis of
the C-arm, and this may influence the planning of the intervention.
Collimators having asymmetrical properties may also be used. They
may be better suited for shielding when working under a
"generalized bulls-eye view".
[0068] As an additional aid to ascertain how precisely the planned
needle path agrees with (X-ray) optical axis of the C-arm system,
the optical axis may be considered to be defined by the direction
of the laser beam. The deviation from the target point (for example
in degrees or cm) the discrepancy (in degrees or cm) from the
target point at the user display of the C-arm system may be
displayed. This may also be represented as a "traffic light"
display where the color of an indicator changes as one gets closer
to the target.
[0069] Using such a feedback mechanism, the procedure may be
commenced by moving the C-arm into a "generalized bulls-eye view".
When using the laser, the table can be manually moved until the
patient is positioned in such a way that the C-arm can be moved
into a viewing direction in which the optical system axis
intersects the target point. Once the patient and the C-arm have
been moved to the correct relative location, the laser may turned
on. If the C-arm is moved manually, then a haptic controller may be
used to assure that the position can be approached in a controlled
way but without overshooting. The table in particular can be moved
automatically to a position favorable for the laser mode.
[0070] During the interventional procedure, the C-arm may be
reoriented so as to follow the progress of the intervention. At
first, the C-arm may have been oriented in the "bulls eye view;"
however, this orientation may not be suitable for visualizing the
internal location (the progress) of the interventional device, as
the distance into the patient body would be along the length of the
instrument, which may be a needle, which is visualized as a point
or small circle in the "bull's eye view". Oblique views would be
used rather than axial views to show the progression of the
device.
[0071] The C-arm angulation would need to be changed to obtain a
first progression view at an appropriate oblique angle. It would
perhaps also be changed again so as to obtain a second progression
view, and the like. During this reorientation of the angulation of
the C-arm, it may be possible for collisions to occur. That is, the
physical structure of the C-arm and attachments thereto may intrude
on the physical space of other equipment, personnel, or the
patient. Collision may be avoided by using the coordinate location
information of the overall system and component parts thereof, by
using collision sensors, or by limiting the motions of the C-arm
during the course of an intervention. For example, rotations about
the patient may be performed along the center plane (using a
CRAN/CAUD angle of 0 degrees). Thus, in moving from one orientation
to another, one may first retract the angulation of a C-arm (in the
CRAN/CAUD direction) and then approach a new rotation angle (in the
LAO/RAO direction), and then set the new angulation. This would
provide some certainty of the motions of the C-arm device that
could occur, particularly when the doctor is standing close to the
patient, but has to pivot the C-arm sharply so as to obtain the
desired angulation.
[0072] The use of the combination of the techniques for planning
and performing percutaneous interventions with the C-arm X-ray
device results in aligning the needle using the laser beam, without
exposing the doctor or patient to radiation, and facilitating the
planning and evaluating realizable needle paths when the C-arm or
the patient table cannot be positioned so as to use the laser, and
X-radiation is used to perform the alignment.
[0073] The combination of hardware and software to accomplish the
tasks described herein may be termed a platform or "therapy unit".
The instructions for implementing processes of the platform may be
provided on computer-readable storage media or memories, such as a
cache, buffer, RAM, FLASH, removable media, hard drive or other
computer readable storage media. Computer readable storage media
include various types of volatile and nonvolatile storage media.
The functions, acts or tasks illustrated or described herein may be
executed in response to one or more sets of instructions stored in
or on computer readable storage media. The functions, acts or tasks
may be independent of the particular type of instruction set,
storage media, processor or processing strategy and may be
performed by software, hardware, integrated circuits, firmware,
micro code and the like, operating alone or in combination. Some
aspects of the functions, acts, or tasks may be performed by
dedicated hardware, or manually by an operator.
[0074] In an embodiment, the instructions may be stored on a
removable media device for reading by local or remote systems. In
other embodiments, the instructions may be stored in a remote
location for transfer through a computer network, a local or wide
area network, by wireless techniques, or over telephone lines. In
yet other embodiments, the instructions are stored within a given
computer, system, or device.
[0075] Where the term "data network", "web" or "Internet" is used,
the intent is to describe an internetworking environment, including
both local and wide area networks, where defined transmission
protocols are used to facilitate communications between diverse,
possibly geographically dispersed, entities. An example of such an
environment is the world-wide-web (WWW) and the use of the TCP/IP
data packet protocol, and the use of Ethernet or other known or
later developed hardware and software protocols for some of the
data paths. Often the internetworking environment is provided, in
whole or in part, as an attribute of the facility in which the
platform is located.
[0076] Communications between the devices, systems and applications
may be by the use of either wired or wireless connections. Wireless
communication may include, audio, radio, lightwave or other
technique not requiring a physical connection between a
transmitting device and a corresponding receiving device. While the
communication may be described as being from a transmitter to a
receiver, this does not exclude the reverse path, and a wireless
communications device may include both transmitting and receiving
functions. Such wireless communication may be performed by
electronic devices capable of modulating data as signals on carrier
waves for transmission, and receiving and demodulating such signals
to recover the data. The devices may be compatible with an industry
standard protocol such as IEEE 802.11b/g, or other protocols that
exist, or may be developed.
[0077] Generally a medical workflow follows hospital routine
procedures prior to and subsequent to the performance of diagnostic
tests and treatment. The patient will have been admitted to the
hospital and assigned to a medical treatment specialty. The patient
demographic information may be entered into the hospital
information processing system as part of the admitting procedures,
and may be updated as needed.
[0078] In a workflow method example, the patient may be transported
to the treatment room and positioned on the treatment table. Such a
transportation step may be manual or may use robotic devices.
Herein, it would be understood by a person of skill in the art that
robotic devices may be generally substituted for a human activity,
or used to facilitate a human activity, as such robotic devices are
being introduced into the hospital environment. The use of such
robotic devices may be presumed as at least an optional part of the
workflow, unless specifically excluded.
[0079] Three dimensional imaging data (voxel data) may have been
previously obtained during diagnosis. Often this data is suitable
for at least the planning stage of the interventional treatment, as
the target will have been already identified. Providing that the
previously obtained data is satisfactory, the voxel data may be
processed to produce images that are registered with images of the
obtained by the C-arm X-ray device used during the interventional
phase. Such images may have been taken with a breathing monitor, if
the thoracic region is involved, using fixtures to position the
patient, or by applying radio-opaque markers to the skin of the
patient in the area of treatment.
[0080] To the extent that the previously obtained voxel data can be
co-registered with the present C-arm apparatus, the planning of
intervention may be performed using synthetic images formed from
the prior voxel data. Such planning may be performed entirely as a
synthetic (computational) process, using the voxel data and a
parameter set locating the various components of the treatment
apparatus, including the C-arm, patient table, the interventional
device (e.g., the needle), the target, and the patient. An
objective of the planning process is to determine if the patient
can be positioned such that the intervention can be performed with
the needle aligned with the optical axis of the C-arm. Success in
this planning would result in a "bull's eye view". Such planning
may need to be performed in an iterative manner, as a first plan
may result in a "generalized bull's eye view." The doctor may
decide that the generalized bull's eye view is a sufficient for the
procedure.
[0081] Alternatively, the positioning may be re-planned so that the
generalized bull's eye view lies closer to the optical axis of the
C-arm system so as to make more efficient use of the collimator.
This usually would result in re-positioning of the patient table.
In this circumstance, the skin penetration point may be identified
by the synthetic views and the radiation views used to align the
axis of the needle, while confirming the coincidence of the aligned
needle with the target. Both the active radiation view and
synthetic views may be used in the process.
[0082] In another alternative, the positioning may be re-planned so
that the "bull's eye view" is obtained. In this circumstance, the
skin entry point and the target lie along the optical axis of the
C-arm. This may be confirmed, if desired, by radiation with a
narrow collimation, or the alignment of the needle may be performed
using a laser guide defining the optical axis of the C-arm. The
laser guide is usually attached perpendicularly to the X-ray
detector, as the X-ray emitter is usually positioned beneath the
patient table so as to reduce the radiation dosage to the patient's
eyes when X-rays are being emitted.
[0083] In another aspect, during the planning or re-planning
process, once an apparently satisfactory angulation and patient
table location has been obtained, the angulations that may be
desired for obtaining progression views may be explored. That is,
the oblique views which may be desired to confirm the progress of
the needle along its path, and the depth of penetration, and the
intersection of the needle with the target may be simulated. The
entire image may be reconstructed, or only the entry point and
target may be used. A synthetic path may be displayed so as to
assist in visualizing the expected result. In this manner, the
planning process also considers the possibility that satisfactory
progression views may not be obtainable due to interference between
the C-arm, other equipment, the patient, and the doctor. The
interventional path may be re-planned to determine if a more
satisfactory planned path for the needle may be determined.
[0084] If the patient is not already on the patient table, the step
moving the patient into position on the table is performed so that
the patient may be moved into a preplanned position. This may be
confirmed by taking X-ray images if deemed desirable.
[0085] Where a bull's eye view has been obtained, the needle or
other interventional device may be aligned by observing the laser
spot on the patient skin, placing the penetrating end on the spot,
and orienting the axis of the device along the laser beam.
Similarly, a fixture attached so that the interventional device may
be physically oriented may also be used. Once the interventional
device has been oriented, one of a number of known techniques may
be used to maintain the orientation prior to, during, or after
penetration.
[0086] Where a generalized bull's eye view has been obtained, the
C-arm is positioned using the planned angulation for penetration,
and using a real time fluoroscopic image. The penetrating point is
positioned at the determined penetration point by comparing the
real-time position with the synthetic bull's eye image, or by
orienting the needle so that a real-time generalized bull's eye is
obtained. Once the interventional device has been oriented such
that the penetration axis intersects the target, the interventional
device may be held in position mechanically, similarly to the
situation which obtains for the bull's eye case.
[0087] The procedure may now proceed using the aligned
interventional instrument. As the instrument is advanced into the
patient's body, the C-arm angulation may be changed to one of the
positions that may be suitable for progression views, and such
additional X-ray images obtained as are considered needed by the
doctor to verify or correct the path of the interventional
instrument towards the target, and to verify reaching the
target.
[0088] In an example, shown in FIG. 3, a method of planning or
performing an interventional procedure 500 may include positioning
a patient such that a three dimensional voxel image data set can be
obtained (step 510). The three dimensional voxel data set may be
used to identify a target area or target volume to be accessed
during the interventional procedure (step 520). Volume rendering
techniques may be used to plan the path of an interventional device
(step 530). For a position of the patient on the patient table, the
angulation of a C-arm X-ray device is preferably planned such that
skin entry point and target in the patient are projected onto each
other (step 540). In the event that a satisfactory "bull's eye" is
not obtained (but a generalized bull's eye" is obtained) the
positioning may be re-planned by, for example, repositioning the
patient table to bring the target area closer to the optical axis
of the C-arm (step 550). Step 550 may be performed iteratively
until a satisfactory result is obtained, although this may still
not be a bull's eye situation.
[0089] When the desired angulation and patient table positions have
been determined, an optional step (step 560) may be performed to
determine whether the C-arm may be positioned so as to obtain
satisfactory progressions views. This step is dependent on the
complexity of the procedure to be performed.
[0090] After planning the procedure, the patient (if not already
present) is placed on the patient table and the orientation of the
patient with respect to the C-arm adjusted so as to conform to the
planned location. This location may be confirmed by sensors, by
radiographic markers, or by the registration of fluoroscopic images
with the previously obtained voxel data set (step 570).
[0091] Where a bull's eye orientation has been obtained, the
penetrating end of the interventional device is positioned with
respect to the skin entry point using a laser, or a mechanical
device oriented along the optical axis of the C-arm (step 580), and
the long axis of the interventional device oriented so as to
coincide with the optical axis. Other laser configurations, such as
a fan beam, may be used. After alignment, the position may be
maintained or regained using known techniques.
[0092] Where a generalized bull's eye is the most satisfactory
orientation that is available for use in the circumstance, the
penetrating end of the interventional device is located with
respect to one of the target or a synthetic entry point on a
real-time radiographic image, and the axis of the interventional
device is oriented so as to lie along the path between the
determined skin entry point and the target (step 590). After
alignment, the position may be maintained or regained using known
techniques.
[0093] The interventional procedure may be then performed by
advancing the interventional device so as to penetrate the skin
(step 600). During the interventional procedure, the needle, for
example, having been aligned as previously described is advanced so
as to penetrate the patient skin along the pre-planned intervention
path (step 610).
[0094] At a juncture where the doctor may wish to confirm the
alignment or penetration depth of needle, the C-arm is re-angulated
so as to obtain a progression fluoroscopic view (step 620). To aid
the interpretation of the resultant radiograph, a synthetic line
may be overlaid on the radiograph indicating the projection of the
planned interventional path on the specific view. Intermediate
positions may be presented in synthesized views. The position of
the C-arm relative to the room coordinate system is known through
the previously preformed registration steps. Step 620 is performed
as many times as the doctor considers necessary to achieve a
satisfactory positioning of the needle with respect to the target,
which may be, for example, a suspected tumor to be biopsied.
[0095] The angulation may be returned to that of the bull's eye
view, or the generalized bull's eye view that was determined in
steps 540 and 550 so as to verify or adjust the axial alignment.
When the progression views or a "dead-reckoning" calculation shows
that the needle tip is in the proper relationship to the target
(angle and distance), the specific procedure may be performed (step
630). The procedure may include obtaining a biopsy, administering a
medication, applying cement, or the like, depending on the syndrome
being treated or diagnosed.
[0096] While the workflows and methods disclosed herein have been
described and shown with reference to particular steps performed in
a particular order, it will be understood that these steps may be
combined, sub-divided, or reordered to from an equivalent workflow
method without departing from the teachings of the present
invention. Accordingly, unless specifically indicated herein, the
order and grouping of steps is not a limitation of the present
invention.
[0097] Although only a few exemplary embodiments of this invention
have been described in detail above, those skilled in the art will
readily appreciate that many modifications are possible in the
exemplary embodiments without materially departing from the novel
teachings and advantages of the invention. Accordingly, all such
modifications are intended to be included within the scope of this
invention as set forth in the following claims.
* * * * *