Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FILTER SYSTEM AND METHOD FOR IMAGING A SUBJECT
FIELD
[0001]
The present disclosure relates to imaging a subject, and particularly to
a system to acquire image data with a duel energy imaging system.
BACKGROUND
[0002]
This section provides background information related to the present
disclosure which is not necessarily prior art.
[0003] A
subject, such as a human patient, may select or be required to
undergo a surgical procedure to correct or augment an anatomy of the subject.
The
augmentation of the anatomy can include various procedures, such as movement
or
augmentation of bone, insertion of an implant (i.e. an implantable device), or
other
appropriate procedures. A surgeon can perform the procedure on the subject
with
images of the subject that can be acquired using imaging systems such as a
magnetic
resonance imaging (MRI) system, computed tomography (CT) system, fluoroscopy
(e.g. C-Arm imaging systems), or other appropriate imaging systems.
[0004]
Images of a subject can assist a surgeon in performing a procedure
including planning the procedure and performing the procedure. A surgeon may
select
a two dimensional image or a three dimensional image representation of the
subject.
The images can assist the surgeon in performing a procedure with a less
invasive
technique by allowing the surgeon to view the anatomy of the subject without
removing
the overlying tissue (including dermal and muscular tissue) when performing a
procedure.
SUMMARY
[0005]
This section provides a general summary of the disclosure, and is not
a comprehensive disclosure of its full scope or all of its features.
[0006]
According to various embodiments, a system to acquire image data of
a subject, such as a living patient (e.g. a human patient), with an imaging
system may
use a plurality of energies. Further, enhanced contrast imaging can include a
contrast
agent with the plurality of energies or without. An imaging system having the
plurality of
energies may include a first energy source with a first energy parameters and
a second
energy source with a second energy parameters to energize a source. Further,
the
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imaging system may include a plurality of sources (each source may have the
same
trajectory or path), wherein each source includes one or more different energy
characteristics.
[0007]
The imaging system can also include a pump operable to inject a
contrast agent into the subject based on an instruction. A controller can be
in
communication with both the imaging system and the pump to provide the
instruction to
the pump to inject the contrast agent. The imaging system can communicate with
the
pump through the controller regarding timing of the injection of a contrast
agent into the
patient and is further operable to acquire image data based upon the timing of
the
injection of the contrast agent and/or the clinical procedure.
[0008]
The imaging system may further include one or more filters to ensure,
and/or assist in ensuring, appropriate or selected separation between the
first energy
characteristics and the second energy characteristics. The first energy
characteristics
may be selected to provide a first x-ray energy spectra with the first energy
characteristics and a second x-ray energy spectra at the second energy
characteristics.
The filter may be provided at a selected time to assist in ensuring
appropriate or
selected spectra for imaging the subject, such as eliminating possible or
actual overlap
of the x-ray energy spectra.
[0009] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples in this
summary are
intended for purposes of illustration only and are not intended to limit the
scope of the
present disclosure.
DRAWINGS
[0010] The
drawings described herein are for illustrative purposes only of
selected embodiments and not all possible implementations, and are not
intended to
limit the scope of the present disclosure.
[0011]
Fig. 1 is an environmental view of an imaging system in an operating
theatre;
[0012] Fig. 2
is a detailed schematic view of an imaging system with a dual
energy source system;
[0013]
Fig. 3 is a detailed view of a filter assembly according to various
embodiments;
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[0014] Fig. 4 is a detailed view of a filter assembly, according
to various
embodiments;
[0015] Fig. 5 is a detailed view of a filter assembly, according
to various
embodiments;
[0016] Fig. 6 is a perspective view of a drive assembly for the filter
assembly
illustrated in Fig. 5;
[0017] Fig. 7 is a flowchart of a synchronization method;
[0018] Fig. 8 is a detailed view of a filter assembly, according
to various
embodiments;
[0019] Fig. 9 is a view of a multiple-axis collimator assembly, according
to
various embodiments;
[0020] Fig. 10A is a first perspective view of a X and Y axis
selection
assembly for the multiple-axis collimator assembly, according to various
embodiments;
[0021] Fig. 10B is a second perspective view of the X and Y axis
selection
assembly of Fig. 10A for the multiple-axis collimator assembly, according to
various
embodiments;
[0022] Fig. 11 is a plan view of a X and Y axis selection assembly
for the
multiple-axis collimator assembly, according to various embodiments;
[0023] Fig. 12 is a perspective view of a X and Y axis selection
assembly for
the multiple-axis collimator assembly, according to various embodiments;
[0024] Fig. 13 a detailed view of a multiple filter filter-
assembly, according to
various embodiments; and
[0025] Fig. 14 a detailed view of a multiple filter filter-
assembly, according to
various embodiments.
[0026] Corresponding reference numerals indicate corresponding parts
throughout the several views of the drawings.
DETAILED DESCRIPTION
[0027] Example embodiments will now be described more fully with
reference
to the accompanying drawings.
[0028] With reference to Fig. 1, in an operating theatre or
operating room 10,
a user, such as a surgeon 12, can perform a procedure on a subject, such as a
patient,
14. In performing the procedure, the user 12 can use an imaging system 16 to
acquire
image data of the patient 14 to allow a selected system to generate or create
images to
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assist in performing a procedure. A model (such as a three-dimensional (3D)
image)
can be generated using the image data and displayed as an image 18 on a
display
device 20. The display device 20 can be part of and/or connected to a
processor
system 22 that includes an input device 24, such as a keyboard, and a
processor 26
which can include one or more processors or microprocessors incorporated with
the
processing system 22 along with selected types of non-transitory and/or
transitory
memory. A connection 28 can be provided between the processor 26 and the
display
device 20 for data communication to allow driving the display device 20 to
display or
illustrate the image 18.
[0029] The
imaging system 16 can include an 0-Arm imaging system sold
by Medtronic Navigation, Inc. having a place of business in Louisville, CO,
USA. The
imaging system 16, including the 0-Arm imaging system, or other appropriate
imaging
systems may be in use during a selected procedure, such as the imaging system
described in U.S. Patent App. Pubs. 2012/0250822, 2012/0099772, and
2010/0290690,
all incorporated herein by reference.
[0030]
The imaging system 16, when, for example, including the 0-Arm
imaging system, may include a mobile cart 30 that includes a controller and/or
control
system 32. The control system may include a processor 33a and a memory 33b
(e.g. a
non-transitory memory). The memory 33b may include various instructions that
are
executed by the processor 33a to control the imaging system, including various
portions
of the imaging system 16. An imaging gantry 34 in which is positioned a source
unit 36
and a detector 38 may be connected to the mobile cart 30. The gantry may be 0-
shaped or toroid shaped, wherein the gantry is substantially annular and
includes walls
that form a volume in which the source unit 36 and detector 38 may move. The
mobile
cart 30 can be moved from one operating theater to another and the gantry 34
can
move relative to the cart 30, as discussed further herein. This allows the
imaging
system 16 to be mobile and moveable relative to the subject 14 thus allowing
it to be
used in multiple locations and with multiple procedures without requiring a
capital
expenditure or space dedicated to a fixed imaging system. The control system
may
include a processor such as a general purpose processor or a specific
application
processor and a memory system (e.g. a non-transitory memory such as a spinning
disk
or solid state non-volatile memory). For example, the memory system may
include
instructions to be executed by the processor to perform functions and
determine
results, as discussed herein.
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[0031]
The source unit 36 may be an x-ray emitter that can emit x-rays
through the patient 14 to be detected by the detector 38. As is understood by
one
skilled in the art, the x-rays emitted by the source 36 can be emitted in a
cone and
detected by the detector 38. The source/detector unit 36/38 is generally
diametrically
opposed within the gantry 34. The detector 38 can move in a 3600 motion around
the
patient 14 within the gantry 34 with the source 36 remaining generally 180
opposed
(such as with a fixed inner gantry or moving system) to the detector 38. Also,
the
gantry 34 can move isometrically relative to the subject 14, which can be
placed on a
patient support or table 15, generally in the direction of arrow 40 as
illustrated in Fig. 1.
The gantry 34 can also tilt relative to the patient 14 illustrated by arrows
42, move
longitudinally along the line 44 relative to a longitudinal axis 14L of the
patient 14 and
the cart 30, can move up and down generally along the line 46 relative to the
cart 30
and transversely to the patient 14, to allow for positioning of the
source/detector 36/38
relative to the patient 14. The imaging device 16 can be precisely controlled
to move
the source/detector 36/38 relative to the patient 14 to generate precise image
data of
the patient 14. The imaging device 16 can be connected with the processor 26
via
connection 50 which can include a wired or wireless connection or physical
media
transfer from the imaging system 16 to the processor 26. Thus, image data
collected
with the imaging system 16 can be transferred to the processing system 22 for
navigation, display, reconstruction, etc.
[0032]
The source 36, as discussed herein, may include one or more sources
of x-rays for imaging the subject 14. In various embodiments the source 36 may
include a single source that may be powered by more than one power source to
generate and/or emit x-rays at different energy characteristics. Further, more
than one
x-ray source may be the source 36 that may be powered to emit x-rays with
differing
energy characteristics at selected times.
[0033]
According to various embodiments, the imaging system 16 can be
used with an un-navigated or navigated procedure. In a navigated procedure, a
localizer and/or digitizer, including either or both of an optical localizer
60 and an
electromagnetic localizer 62 can be used to generate a field and/or receive
and/or send
a signal within a navigation domain relative to the patient 14. The navigated
space or
navigational domain relative to the patient 14 can be registered to the image
18.
Correlation, as understood in the art, is to allow registration of a
navigation space
defined within the navigational domain and an image space defined by the image
18. A
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patient tracker or dynamic reference frame 64 can be connected to the patient
14 to
allow for a dynamic registration and maintenance of registration of the
patient 14 to the
image 18.
[0034] The patient
tracking device or dynamic registration device 64 and an
instrument 66 can then be tracked relative to the patient 14 to allow for a
navigated
procedure. The instrument 66 can include a tracking device, such as an optical
tracking device 68 and/or an electromagnetic tracking device 70 to allow for
tracking of
the instrument 66 with either or both of the optical localizer 60 or the
electromagnetic
localizer 62. The
instrument 66 can include a communication line 72 with a
navigation/probe interface device 74 such as the electromagnetic localizer 62
with
communication line 76 and/or the optical localizer 60 with communication line
78.
Using the communication lines 74, 78 respectively, the interface 74 can then
communicate with the processor 26 with a communication line 80. It will be
understood
that any of the communication lines 28, 50, 76, 78, or 80 can be wired,
wireless,
physical media transmission or movement, or any other appropriate
communication.
Nevertheless, the appropriate communication systems can be provided with the
respective localizers to allow for tracking of the instrument 66 relative to
the patient 14
to allow for illustration of a tracked location of the instrument 66 relative
to the image 18
for performing a procedure.
[0035] One skilled
in the art will understand that the instrument 66 may be
any appropriate instrument, such as a ventricular or vascular stent, spinal
implant,
neurological stent or stimulator, ablation device, or the like. The instrument
66 can be
an interventional instrument or can include or be an implantable device.
Tracking the
instrument 66 allows for viewing a location (including x,y,z position and
orientation) of
the instrument 66 relative to the patient 14 with use of the registered image
18 without
direct viewing of the instrument 66 within the patient 14.
[0036] Further, the
gantry 34 can include an optical tracking device 82 or an
electromagnetic tracking device 84 to be tracked with the respective optical
localizer 60
or electromagnetic localizer 62. Accordingly, the imaging device 16 can be
tracked
relative to the patient 14 as can the instrument 66 to allow for initial
registration,
automatic registration, or continued registration of the patient 14 relative
to the image
18. Registration and navigated procedures are discussed in the above
incorporated
U.S. Patent No. 8,238,631, incorporated herein by reference. Upon registration
and
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tracking of the instrument 66, an icon 174 may be displayed relative to,
including
superimposed on, the image 18.
[0037]
Turning reference to Fig. 2, according to various embodiments, the
source 36 can include a single x-ray tube 100 that can be connected to a
switch 102
that can interconnect a first power source A 104 and a second power source B
106 with
the x-ray tube 100. X-rays can be emitted from the x-ray tube 100 generally in
a cone
shape 108 towards the detector 38 and generally in the direction from the
source 100
as indicated by arrow, beam arrow, beam or vector 110. The switch 102 can
switch
between the power source A 104 and the power source B 106 to power the x-ray
tube
100 at different voltages and/or amperages to emit x-rays at different energy
characteristics generally in the direction of the vector 110 towards the
detector 38. The
vector 110 may be a central vector or ray within the cone 108 of x-rays. An x-
ray beam
may be emitted as the cone 108 or other appropriate geometry. The vector 110
may
include a selected line or axis relevant for further interaction with the
beam, such as
with a filter member, as discussed further herein.
[0038]
It will be understood, however, that the switch 102 can also be
connected to a single variable power source that is able to provide power
characteristics at different voltages and/or amperages rather than the switch
102 that
connects to two different power sources A 104 and B 106. Also, the switch 102
can be
a switch that operates to switch a single power source between different
voltages and
amperages. Further, the source 36 may include more than one source that is
configured or operable to emit x-rays at more than one energy characteristic.
The
switch, or selected system, may operate to power the two or more x-rays tubes
to
generate x-rays at selected times.
[0039] The
patient 14 can be positioned within the x-ray cone 108 to allow for
acquiring image data of the patient 14 based upon the emission of x-rays in
the
direction of vector 110 towards the detector 38.
[0040]
The two power sources A and B 104, 106 can be provided within the
source housing 36 or can be separate from the source 36 and simply be
connected with
the switch 102 via appropriate electric connections such as a first cable or
wire 112 and
a second cable or wire 114. The switch 102 can switch between the power source
A
104 and the power source B 106 at an appropriate rate to allow for emission of
x-rays
at two different energies through the patient 14 for various imaging
procedures, as
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discussed further herein. The differing energies can be used for material
separation
and/or material enhanced reconstruction or imaging of the patient 14.
[0041]
The switching rate of the switch 102 can include about 1 millisecond
(ms) to about 1 second, further including about 10 ms to 500 ms, and further
including
about 50 ms. According to various embodiments, the power may be switched at a
rate
of about 30 Hz. Thus, x-rays may be emitted with energy characteristics
according to
each power source A and B for about 33 ms.
[0042]
Further, the power source A 104 and the power source B 106 can be
provided to include different power characteristics, including different
voltages and
different amperages, based upon selected contrast enhancement requirements.
The
different power characteristics allow the x-rays to include different energy
characteristics. The differing energy characteristics of two or more different
x-rays
emissions interact and are attenuated (e.g. absorbed, blocked, deflected,
etc.) by the
same material differently. For example, as discussed further herein, different
energy
characteristics can be selected to allow for contrast enhancement (e.g.
enhanced
viewing and identification) between soft tissue (e.g. muscle or vasculature)
and hard
tissue (e.g. bone) in the patient 14, that may be done without any contrast
agent
present. Also, differing energy characteristics may assist in increasing
contrast
between a contrast agent injected in the patient 14 and an area without a
contrast
agent injected in the patient 14.
[0043]
As discussed further herein, each emission of x-rays at a selected
energy characteristic may include a x-ray energy spectral range. The x-ray
energy
spectral range for any given powering level, however, may be generally broad.
Broad,
for example, may include a range of energies at which x-rays are emitted and
not only
at a specific and/or single energy level. Thus, even if two different
powering
characteristics are used, emitted x-rays may overlap between two emissions of
x-rays
generated with the two power sources A and B. A filter assembly 200 may
include a
filter member of a filter material, as discussed herein, which may be used to
attenuate
some of the spectra of one or more of an emission of x-rays. In attenuating
part of a
spectrum of an emission of x-rays, differentiation between two emissions may
be
greater and spectral overlap may be minimized. For example, the filter member
may
attenuate lower energy x-rays from when the x-ray tube is powered by the
higher
powered power source A or B.
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[0044] As an example, the power source A 104 can have a voltage of about
75 kV and can have an amperage of about 50 mA, which can differ from the power
source B which can have a voltage of 150 kV and 20 mA. The selected voltages
and
amperages can then be switched with the switch 102 to power the x-ray tube 100
to
emit the x-rays with selected energy characteristics generally in the
direction of the
vector 110 at and/or through the patient 14 to the detector 38. It will be
understood that
the range of voltages for the power source A may be about 40 kV to about 80 kV
and
the amperages can be about 10 mA to about 500 mA. Generally, the power
characteristic differences between the first power source A 104 and the second
power
source B 106 can be about 40 kV to about 60 kV and about 20 mA to about 150
mA. In
other words, for example, the power source B may power the x-ray tube 100 at a
voltage that is about 40 kV to about 60 k V and an amperage that is about 20
mA to
about 150 mA greater than power source A. In addition to the energy and mA
difference, the pulse width of the exposure may be varied as well from 1 ms to
50ms.
[0045] The
dual power sources allow for dual energy x-rays to be emitted by
the x-ray tube 100. As discussed above, the two or dual energy x-rays can
allow for
enhanced and/or dynamic contrast reconstruction of models of the subject 14
based
upon the image data acquired of the patient 14. It is understood, however,
that more
than two power sources may be provided or they may be altered during operation
to
provide x-rays at more than two energy characteristics. The discussion herein
of two or
duel energy is merely exemplary and not intended to limit the scope of the
present
disclosure, unless specifically so stated.
[0046]
Generally, an iterative or algebraic process can be used to reconstruct
the model (such as for the image 18) of at least a portion of the patient 14
based upon
the acquired image data. It is understood that the model may include a three-
dimensional (3D) rendering of the imaged portion of the patient 14 based on
the image
data. The rendering may be formed or generated based on selected techniques,
such
as those discussed herein.
[0047] The power sources can power the x-ray tube 100 to generate two
dimension (2D) x-ray projections of the patient 14, selected portion of the
patient 14, or
any area, region or volume of interest. The 2D x-ray projections can be
reconstructed,
as discussed herein, to generate and/or display three-dimensional (3D)
volumetric
models of the patient 14, selected portion of the patient 14, or any area,
region or
volume of interest. As discussed herein, the 2D x-ray projections can be image
data
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acquired with the imaging system 16, while the 3D volumetric models can be
generated
or model image data.
[0048]
For reconstructing or forming the 3D volumetric image, appropriate
algebraic techniques include Expectation maximization (EM), Ordered Subsets EM
(OS-EM), Simultaneous Algebraic Reconstruction Technique (SART) and Total
Variation Minimization (TVM), as generally understood by those skilled in the
art. The
application to perform a 3D volumetric reconstruction based on the 2D
projections
allows for efficient and complete volumetric reconstruction. Generally, an
algebraic
technique can include an iterative process to perform a reconstruction of the
patient 14
for display as the image 18. For example, a pure or theoretical image data
projection,
such as those based on or generated from an atlas or stylized model of a
"theoretical"
patient, can be iteratively changed until the theoretical projection images
match the
acquired 2D projection image data of the patient 14. Then, the stylized model
can be
appropriately altered as the 3D volumetric reconstruction model of the
acquired 2D
projection image data of the selected patient 14 and can be used in a surgical
intervention, such as navigation, diagnosis, or planning. The theoretical
model can be
associated with theoretical image data to construct the theoretical model. In
this way,
the model or the image data 18 can be built based upon image data acquired of
the
patient 14 with the imaging device 16.
[0049] The 2D
projection image data can be acquired by substantially annular
or 360 orientation movement of the source/detector 36/38 around the patient
14 due to
positioning of the source/detector 36/38 moving around the patient 14 in the
optimal
movement. An optimal movement may be a predetermined movement of the
source/detector 36/38 in a circle alone or with movement of the gantry 34, as
discussed
above. An optimal movement may be one that allows for acquisition of enough
image
data to reconstruct a select quality of the image 18. This optimal movement
may allow
for minimizing or attempting to minimize exposure of the patient 14 and/or the
user 12
to x-rays by moving the source/detector 36/38 along a path to acquire a
selected
amount of image data without more or substantially more x-ray exposure.
[0050] Also,
due to movements of the gantry 34, the detector need never
move in a pure circle, but rather can move in a spiral helix, or other rotary
movement
about or relative to the patient 14. Also, the path can be substantially non-
symmetrical
and/or non-linear based on movements of the imaging system 16, including the
gantry
34 and the detector 38 together. In other words, the path need not be
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that the detector 38 and the gantry 34 can stop, move back the direction from
which it
just came (e.g. oscillate), etc. in following the optimal path. Thus, the
detector 38 need
never travel a full 3600 around the patient 14 as the gantry 34 may tilt or
otherwise
move and the detector 38 may stop and move back in the direction it has
already
passed.
[0051]
In acquiring image data at the detector 38, the dual energy x-rays
generally interact with a tissue and/or a contrast agent in the patient 14
differently
based upon the characteristics of the tissue or the contrast agent in the
patient 14 and
the energies of the two x-rays emitted by the x-ray tube 100. For example, the
soft
tissue of the patient 14 can absorb or scatter x-rays having an energy
produced by the
power source A 104 differently than the x-rays having energy produced by the
power
source B 106. Similarly, a contrast agent, such as iodine, can absorb or
scatter the x-
rays generated by the power source A 104 differently from those generated by
the
power source B 106. Switching between the power source A 104 and the power
source
B 106 can allow for determination of different types of material properties
(e.g. hard or
soft anatomy or between two types of soft anatomy (e.g. vessels and
surrounding
tissue)), contrast agent, implants (e.g. metal implants) and surrounding
natural anatomy
(e.g. bone), or etc. within the patient 14. By switching between the two power
sources
104, 106 and knowing the time when the power source A 104 is used to generate
the x-
rays as opposed to the power source B 106 to generate the x-rays the
information
detected at the detector 38 can be used to identify or segregate the different
types of
anatomy or contrast agent being imaged.
[0052]
A timer can be used to determine the time when the first power source
A 104 is being used and when the second power source B 106 is being used. This
can
allow the images to be indexed and separated for generating different models
of the
patient 14. Also, as discussed herein, the timer, which can be a separate
system or
included with the imaging system 16 or the processor system 26, can be used to
index
image data generated with the contrast agent injected into the patient 14.
[0053]
At least because the x-ray tube 100 is in a moveable imaging system,
such as the imaging system 16, it can be moved relative to the patient 14.
Thus, the x-
ray tube 100 may move relative to the patient 14 while the energy for the x-
ray tube 100
is being switched between the power source A 104 and the power source B 106.
Accordingly, an image acquired with the power source A 104 may not be at the
same
pose or position relative to the patient 14 as the power source B 106. If the
model is
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desired or selected to be formed of a single location in the patient 14,
however, various
interpolation techniques can be used to generate the model. Interpolation may
between image data acquired at a first time and image data acquired at a
second time.
The image data at the first and second times may be generated with the two
different
energies. Thus, the model may be formed including image data from both
energies
using interpolation between the acquired image data. Further, the
interpolation may be
to account for an amount of movement (e.g. linear, rotational, etc.) of the x-
ray tube 100
between when the projection with the power source A 104 and the projection
with the
power source B 106 was acquired.
[0054] The
dual energy of the x-rays emitted by the x-ray tube 100 due to the
two power sources 104, 106 can allow for substantially efficient and enhanced
contrast
discrimination determination between the vasculature and the musculature of
the
patient 14. Moreover, the switching by a switch 102 between the power source A
104
and the power source B 106 allows for an efficient construction of the source
36 where
the single x-ray tube 100 can allow for the generation of x-rays at two
different energies
to allow for enhanced or dynamic contrast modeling of the patient 14, such as
modeling
the vasculature of the patient 14 including a contrast agent therein.
[0055]
The patient 14 can also be imaged with the injected contrast agent by
gating the acquisition of the image data of the patient 14 based upon the
injection of the
contrast agent. According to various embodiments, a contrast agent, such as
iodine,
can be injected into the patient 14 to provide additional contrast in the
image data
acquired of the patient 14 with the imaging system 16. During the image
acquisition,
however, the contrast agent flows through the vasculature of the patient 14
from an
artery phase to a venous phase. For example, the contrast agent can be
injected into
the patient 14 into an artery where the contrast agent can flow through the
vasculature
of the patient 14 to the heart, through the heart, to the lungs through the
venous
system, back through the heart, and out into the arterial portion of the
vasculature of the
patient 14.
[0056]
When acquiring image data of the patient 14 to identify or reconstruct
the vasculature of the patient 14, knowing the timing of when image data is
acquired
relative to the timing of the injection of the contrast agent can allow for a
reconstruction
of the various phases based on the known movement of the contrast agent
through
structures of the patient 14. In other words, it is generally understood that
the contrast
agent will flow through the patient 14 as described above at a known or
generally
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known rate. The dual energy x-rays, generated with the x-ray tube 100 based
upon the
power source A 104 and the power source B 106, can be used to generate image
data
of any portion of the vasculature of the patient 14.
[0057]
The acquisition of the image data, therefore, can be gated relative to
the injection of the contrast agent into the patient 14. For example, the
controls 32 of
the imaging system 16 can be associated or communicate with a control of a
pump 170
(illustrated in Fig. 1) through a communication line 172 (illustrated in Fig.
1) that pumps
or injects the contrast agent into the patient 14. The communication 172
between the
pump 170 and the imaging device control 32 can be any appropriate
communication
such as a wired, wireless, or other data communication system. Also, the
control for
the pump 170 can be incorporated into the controls 32 of the imaging system 16
or the
processor system 26.
[0058]
Duel energy imaging systems may include those disclosed in U.S. Pat.
App. Pub. Nos. 2012/0099768 and 2012/0097178, both incorporated herein by
reference.
[0059]
In addition to the generation of x-rays of different energies, including
dual energy x-rays as discussed above, the filter assembly 200 can be used to
assist in
insuring or creating a select differentiation between x-ray spectras of x-rays
of the two
different energies. The filter assembly 200 can also be timed in conjunction
with the
pump 170 and the acquisition of the image data to assist in gating image data
acquired
of the patient 14. Therefore the filter assembly 200 can be operated to image
the
patient 14 to achieve the differentiation between the dual energies of the x-
rays.
[0060]
Turning reference to FIG. 3 a filter assembly 200a is illustrated. The
filter assembly 200a may be provided in the imaging system 16 such that the x-
rays
emitted from the x-ray tube will selectively pass through a filter member 210
of the filter
assembly 200a. The filter assembly 200a may include a motor assembly 220. The
motor assembly 220 may be any appropriate motor assembly that is assembled
into the
imaging system 16 while not interfering with operation of the imaging system
16.
Exemplary motor assemblies include various stepper and/or brushless servo
motors,
such as the Maxon EC-max 30 DC brushless motor sold by Maxon Motor Ag, having
a place of business in Switzerland.
[0061]
Generally the motor assembly 220 may be a motor assembly to
rotationally drive an axle or shaft 224. Mounted to the shaft 224 may be a
filter member
holding member 226. The holding member 226 may be fixed to the axle 224 with a
set
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screw in a bore 228. The shaft 224 may be received within a bore 230 of an
shaft
connection portion 232 of the holding assembly 226. Extending from the shaft
mounting portion 232 may be a filter holding portion 236. The filter member
210 may
be positioned on the holding portion 236 in a selected manner. For example,
the filter
portion 210 may be mounted with a fixative material, such as an adhesive, or
with a
mounting hardware, such as rivets or bolts. According to various embodiments
the filter
member 210 may be a metallic material that is brazed or welded to the holding
portion
236. The holding portion may be formed as a frame, such that x-rays passing
through
the subject will pass only through the filter member 210 and not a portion of
the holding
portion 236.
[0062]
The motor assembly 220 may be driven or controlled with a controller
that is internal to the motor assembly 220. Further, the motor assembly 220
may be
controlled with the imaging controller 32. The imaging system controller 32
may control
the imaging system 16 including the filter assembly 200a to image the patient
14
according to a selected imaging modality. The filter assembly 200a may be
driven or
operated to assist in acquiring dual energy image data of the patient 14, as
discussed
further herein. The imaging sensing controller 32 may control the movement and
position of the source 36 and the operation of the filter assembly 200a. As
discussed
above, the controller 32 may include a memory with a predetermined imaging
protocol
(including timing of imaging, number of image projections, etc.) and a related
timing for
operating the motor assembly 220 to move the filter.
[0063]
The motor assembly 220 may include a motor assembly that is able to
rotate the filter member 210 or the filter holding portion 236 substantially
in either or
both directions of double headed arrow 240 at a selected velocity and stopping
the filter
member 210 at a selected time. Generally, the motor assembly 220 may operate
to
move the filter member 210 in a first direction and then stop and move the
filter member
in a second, such as opposite, direction. For example, during operation the
filter
member 210 may move generally 90 into and out of the beam of x-rays, such as
along
vector 110. As discussed above, the x-ray beam may switch energy
characteristics
depending upon which power source A or B 104, 106 is powering the x-ray tube
100.
The rate of switching may be about 30 Hz. Therefore, the filter member 210 may
need
to accelerate at about 900,000 degrees/s2 to move into the beam path 110 so
that the
filter member 210 is appropriately positioned in about 23 milliseconds.
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[0064]
As schematically illustrated in FIG. 3, the x-ray tube 100 may emit to
the x-rays generally in the direction of the vector 110. The x-rays will then
impinge and
pass through or be blocked by the filter member 210 to be filtered before
reaching the
patient 14 and the detector 38. When the filter 210 is selected to be
filtering the x-rays
from the x-ray tube 100, the filter member 210 may be moved in a first
direction and
positioned as illustrated in FIG. 3 such that the filter member 210 is in a
first position in
the path of the x-rays along ray 110. The filter member 210 may then be moved
in a
second direction and positioned in a second position as illustrated in phantom
at 236' in
FIG. 3 that is out of the x-rays path and not in the ray 110. The movement
from the first
position to the second position by the filter member 210 may be substantially
90 as
illustrated between the carrier 236 and the carrier 236', shown in phantom.
[0065]
The motor assembly 220 may, therefore, be any appropriate motor
that is able to move at a selected speed. The selected speed may include time
for
moving the carrier 236 and emitting x-rays for acquiring image data. In
various
embodiments, therefore, a selected speed may include about 4500 RPM so as to
move
the carrier or filter holding portion 236 at a speed of about 90 about every
20
milliseconds (ms). This would allow the filter 210 to move into and out of the
x-beam
110 about every 33 ms and allow about 10 ms to about 13 ms to be allocated for
acquiring the image data with the x-ray beam 110. Appropriate motors may
include DC
servo motors, AC servo motors, stepper motors, or other appropriate motors.
The
motor assembly 220 may include direct drive or geared assemblies. As
illustrated in
FIG. 3 the shaft 224 may extend directly from the motor and engage directly in
the filter
holding portion 226. It is understood that the motor assembly 220, however,
may also
be provided to operate or move the filter holding portion 236 via a
transmission or other
appropriate non-direct drive system.
[0066]
One or more encoders may be provided in the motor assembly 220 to
determine a position of the motor including the shaft 224. For example, an
encoder 242
may attach to the shaft 224 and a housing 243 of the motor assembly 220 and/or
be
incorporated into the motor assembly 220. The encoder 242 may include
incremental
or absolute encoders that may be optical, magnetic, or inductive. The encoder
242
may track or determine that the position of the shaft 224 and, therefore, the
filter
holding portion 226 fixedly attached to the shaft 224. For example, the
encoder 242
may include a reader or a sensor at both the "in" position and "out" of beam
position
(illustrated in phantom 236'). The encoder 242 may then provide a signal to
the
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controller 32 regarding the sensed location. The encoder 242 may then provide
the
position of the filter holding portion 226 to the image controller 32. The
image controller
32 may operate the motor assembly 220 appropriately to move the filter member
210
into or out of the path 110 of the x-rays from the x-ray tube 100 based on the
timing of
the emission of x-rays at the selected energy and the position of the filter
member 210.
Thus, the movement of the filter member 210 may be timed and selected based on
the
timing and/or emission signal of the x-rays at the selected first or second
energy.
[0067]
Accordingly, during an operation the two power sources A and B 104,
106 may selectively and alternatively power the x-ray tube 100. During a
selected
operation, such as powering the x-ray tube with the power source B 106 the
filter
member 210 may be positioned in the path 110 of the x-rays in the first
position. As the
imaging control system 32 is able to determine and power the x-ray tube 100
with the
power source B 104 the control system 32 may also operate the filter assembly
200a to
move the filter member 210 into the path when powering the x-ray tube 100 with
the set
power source B 104. The encoder 242 may be used to determine that the filter
member 210 is in the appropriate position relative to the path of the x-rays
110 to
ensure the filter 210 is positioned for acquiring image data of the patient
14. When the
power source A is powered to emit x-rays along ray 110, the filter member 210
may be
moved by the motor assembly 220 to the second position (shown in phantom 236'
in
.. Fig. 3) out of the path of the x-rays along ray 110.
[0068]
It is understood, however, that the filter holder may continuously spin
on the shaft 224 in a single direction, such as in a rotation of at least 360
. The
encoder 242 may then provide a signal as to when the filter member is in the
in-beam
position, as illustrated in solid lines in Fig. 3. The movement of the filter
member 210
and the carrier 236 may then be synchronized to the emission of x-rays at a
selected
energy parameter with one of the selected power sources A, B 104, 106.
Synchronization may occur, as discussed herein.
[0069]
Moreover, it is understood that the filter carrier portion 226 may
include more than one filter carrier portion 236 with more than one of the
filter members
210. For example, two filter members may be provided substantially 180 degrees
from
each other. Such that at one speed of rotation, a filter will be in the beam
path 110
twice as often. Further, any appropriate number of filter members may be
provided.
[0070]
As discussed above the filter material may be selected to selectively
eliminate a certain portion of an x-ray spectra. As the x-rays from the x-ray
tube 100
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may be powered with the power source B 104 the x-rays, however, may still
include a
spectra that is greater than selected. Accordingly, the filter member 210 may
filter the
x-rays with the second energy to include a spectra that is narrower or has a
higher or
lower mean energy than may be provided by only powering the x-ray tube 100
with the
power source B 106. Further, the filter material 210 may be selected to
achieve a
selected x-ray spectra, such that its average energy if approximates 60-80 kV
different
than its unfiltered spectrum. Accordingly, selected filter materials may
include copper,
aluminum, or other high-z materials. It is also understood, however, that the
filter
member 210 may be used to filter x-rays powered at the power source A 104.
Furthermore, the filter member 210 may be used to filter x-rays powered with
both
power sources A and B 104, 106. And further, more than one filter member may
be
provided such that a first filter member will filter x-rays powered with the
power source
A 104 and a second filter will filter x-rays with the power source B 106.
[0071]
Turning reference to FIG. 4, a filter assembly 200b is illustrated. The
filter assembly 200b may be incorporated into the imaging system 16 either
with or
alternative to the filter assembly 200a, discussed above. The filter assembly
200b may
include a filter member or portion 260 that may be moved substantially
linearly
generally in two directions in a plane, such as a plane defined by the filter
member 260
and/or parallel thereto, in the direction of double headed arrow 262. The
filter assembly
200b may be positioned so that the filter member 260 may be moved in a first
direction
to a first position to intersect the beam of x-rays along vector 110 emitted
from the x-ray
tube 100, as schematically illustrated in FIG. 4. The filter member 260 on the
filter
carrier 264 may then be moved in a second, such as an opposite or different
direction,
to a second position such that the filter member 260 is out of the x-ray path
along
vector 110. The filter member 260 may be carried on a filter carrier 264 that
is driven
by a linear motor or actuator 270.
[0072]
The linear motor 270 may include a linear motor according to various
embodiments. For example, the linear motor 270 may include appropriate linear
motors that include moveable or fixed magnets and moveable or fixed motor
coils.
Exemplary linear motors include slotless linear motors, balanced linear
motors, etc.
Exemplary commercially available linear motors include the Javelin TM Series
Motors
including models 1486 and 1487 and/or the flatbody JukeTM Series Motors sold
by
Celera Motion having a place of business in Loomis, CA. The linear motor 270
may
move the filter carrier 264 in the plane relative to the ray 110 of the x-rays
at a selected
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rate and/or at a selected time. As discussed above, x-rays at the different
energy
characteristics may be emitted from the x-ray tube 100 at a frequency of about
30 Hz.
Therefore the filter member 260 generally would need to move into the ray 110
within
about 23 milliseconds to allow for an exposure of about 10 milliseconds of the
patient
14 to the x-ray. Thus, the filter member 260 may be timed to move into and out
of the
x-ray beam to affect only the selected beam of x-rays at a selected energy
characteristic, such as to have the effect of eliminating a portion of the
emitted x-ray
spectra.
[0073]
According to various embodiments, the linear motor 270 may include a
stationary linear motor coil 274 and a moving magnet 276. The stationary coil
274 may
be fixed to a structure, such as a base plate or member 278 and/or one or more
linear
bearings 280. The moving magnet 276 positioned over the or relative to the
stationary
linear motor coil 274 may move generally in the direction of the double headed
arrow
262. The filter carrier 264 may be mounted to the moving magnet 276 using an
appropriate mechanism, such as an adhesive, screws, rivets, or the like. For
example,
one or more bores 282 may be provide in the filter carrier 264 to allow for a
fixation
member, such as a screw, to fix the filter carrier 264 to the moving magnet
276.
[0074]
In operation, the moving magnet 276 may be driven in the directions of
arrow 262 by the stationary motor coil 274. The operation of the linear motor
in such a
configuration is generally understood by one skilled in the art, and will not
be described
herein in detail. Nevertheless, the stationary motor coil 274 may be operated
to
sequentially power coils within the stationary motor coil 274 to move the
moveable
magnet 276 via magnetic field interactions with the moveable magnet 276. The
moveable magnet 276 may include permanent and/or electromagnets that interact
with
coils in the stationary coil 274 to move the moveable magnet 276. As the
filter carrier
264 is fixed to moveable magnet 276, the filter carrier 264 carrying the
filter 260 may
move with the moveable magnet 276. The linear bearings 280 may hold and guide
the
filter carrier 264 connected to the moveable magnet 276 in a selected manner.
The
linear bearings 280 may ensure that the filter carrier 264 and the moveable
magnet 276
move generally in the direction of arrow 262.
[0075]
The driving motor coil 274 may be connected to the image controller
32 to operate the motor 270 according to a predetermined timing or gating of
positioning the filter 260 in the x-rays. As discussed above in relation to
the filter
assembly 200a, the image controller 32 controls and determines the timing of
imaging
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with the x-rays. The image controller 32 includes a predetermined timing for
powering
x-rays at selected energies to acquire image data of the patient 14.
Therefore, the
image controller 32 may control the linear motor 270 to move the filter member
260 into
and out of the vector 110 of x-rays from the x-ray tube 100 according to a
determined or
predetermined x-ray imaging plan. As discussed above, the controller 32 may
include a
memory with a predetermined imaging protocol (including timing of imaging,
number of
image projections, etc.) and a related timing for operating the motor assembly
270 to
move the filter.
[0076]
For example, the imaging controller 32 may include a selecting time
and/or frequency of emitting x-rays powered by either or both of the power
source A
104 and the power source B 106. The movement of the filter member 260 into the
x-
ray beam along vector 110 may be selected and timed relative to the emission
of x-
rays. The movement of the filter member 260 with the linear motor 270 may be
synchronized to the emission of the x-rays. In various embodiments, the
movement of
the filter 260 with the linear motor 270 controlled by the controller 32 may
be cyclic
according to a predetermined cycle or may be infrequent according to a
selected
imaging protocol. Nevertheless, the controller 32 may control the motor 270 to
move
the filter member 260 in the direction of the double headed arrow 262 to
position the
filter member 260 in the ray 110 of the x-rays or to move it out of the way.
[0077] The
position of the motor 270 may be determined with an encoder,
such as a linear encoder 290. The linear encoder 290 may include an inductive
encoder having a fixed read head 292 and a rail 294 connected to and moveable
with
the filter carrier 264. It is understood, however, that this may be vice-versa
so that the
read head 292 moves with the moveable with the filter carrier 264 while the
rail 294 is
fixed relative thereto. Nevertheless, the read head 292 may also be connected
to the
controller 32 so that the read head 292 is operable to transmit a signal (e.g.
a position
signal) to the controller 32 regarding a position of the filter carrier 264.
Based on the
signal, the controller 32 may determine an absolute or an incremental position
of the
filter carrier 264. The controller 32 may therefore determine the position of
the filter
member 260 by determining a position of the filter carrier 264 via the encoder
290. It is
understood, however, that the encoder 290 may be any appropriate encoder such
as
an optical encoder, rotary encoder, or alternative linear encoder. Further,
optical and
magnetic technology may be used as an alternative or in addition to an
inductive
encoder.
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[0078]
Moving the filter member 260 in a linear manner via an appropriate
filter carrier 264 may also be performed with other linear motors such as a
lead screw
or ball screw, a balanced linear motor, a worm screw, or other appropriate
drive
mechanism. Further, it will be understood that a linear motor, according to
various
embodiments, may include the drive coil 274 which moves and the magnet 276
that is
fixed. In a moving coil assembly, the filter carrier 264 may be mounted on the
drive coil
274 and the magnetic 276 be fixed to a mounting portion such as the mounting
plate
278 or the bearings 280.
[0079]
With reference to FIG. 5 a filter assembly 200c is illustrated. The filter
assembly 200c may include a filter member 300 that is carried by a filter
carrier 310,
wherein the filter carrier 310 may rotate around an axis on a shaft. The
filter member
300 may be formed of a selected material, including those discussed above, and
fixed
to the filter carrier 310. For example, bores may be formed in the filter
member 300
and one or more screws 312 fix the filter member 300 to the filter carrier 310
by passing
through or engaging the filter member 300 and the filter carrier 310. It is
understood
that other fixation mechanisms may be provided, such as welding, adhesives,
brazing,
or the like, to fix the filter member 300 to the filter carrier 310. The
carrier 310 may
further be provided as a frame such that x-rays that pass through the filter
member 300
and reach the detector pass through the filter member 300, but not the
material of the
filter carrier 310.
[0080]
As illustrated in FIG. 5 the filter carrier 310 may have a curved outer
edge 314 such that the filter carrier 310 includes a radius 316 and has an
outer arcuate
edge 314. The filter carrier 310, therefore, may form at least a part of a
circle or round
member. The combination of the filter carrier 310 and the filter member 300
may have
a selected mass that defines or forms only a portion of a circle. Therefore, a
counterbalance 320 may be fixed to the filter carrier 310 to counter balance
the mass of
the filter member 300 and the filter carrier 310.
[0081]
The counter balance may have an arcuate outer edge 322 and a
substantially similar radius 324 to the radius 316. The counter balance 320,
therefore,
may form with the filter carrier 310 a circle. The counterbalance 320 and the
filter
carrier 310 form a filter carrier assembly 350 to move the filter member 300
relative to
the x-ray to be positioned into or out of the x-rays generally travelling
along the direction
110, as schematically illustrated in FIG. 5.
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[0082]
The filter carrier 310 may rotate around a shaft that has or forms a
central axis 330. The filter carrier 310 may be operated to rotate in two
directions or in
a single direction, such as in the direction of arrow 340 around the axis 330.
In various
embodiments, the filter carrier 310 may be moved to carry the filter member
300 in
substantially one rotational directional.
[0083]
According to various embodiments the filter carrier 310 may be
operated to rotate around the axis 330 at a substantially constant speed and
rotation
per minute (RPM). Therefore, whether the filter member 300 is in the beam path
110 or
an open area of the filter carrier assembly 350 in the beam path 110. As the
filter
carrier 310 rotates around the axis 330 in the direction of arrow 340 in open
air or void
region 344, formed at least in part by the counter balance 320, may also be
spaced or
positioned in the beam path 110. Therefore, the rotation of the filter carrier
310 around
the axis 330 can alternately place the filter member 300 in the beam path 110
or the
void 344 in the beam path 110. It is understood, however, that the filter
member 300
may have a size and moving the filter member 300 cause a void to be in the
beam path,
thus forming a void with a counter balance 320 is not required.
[0084]
The filter carrier 310 on the assembly may need to rotate, such in the
direction of arrow 340, at a selected rate to ensure that the filter member
300 is in the
beam path 110 at a selected time. In this manner, the imaging with a filter
and without
a filter may be gated and controlled by the controller 32. Gating may be based
upon
various and/or predetermined factors such as energy selection of the x-rays,
contrast
agent injection, patient physiological motion (e.g. respiration or heart
beat). As
discussed above the filter member 300 may be positioned in a selected position
in the
beam path 110 to filter a selected portion of x-ray spectra of at least one of
the
emissions of x-rays at one of the energies of the dual x-ray imaging system at
a
selected time. As discussed above, it may be selected to switch the energies
for
generating x-rays of the imaging system at a frequency of about 30 Hz.
Therefore,
moving the filter member into and out of the beam may occur at about 33
milliseconds.
[0085]
As illustrated in FIG. 5, the filter member 300 may be on one side of
the filter carrier assembly 350 and may form about one-half of the
circumference of a
disk, therefore a one-half revolution of the filter carrier assembly 350 may
be required to
ensure movement of the filter member 300 into a first position in the x-ray
beam along
the vector 110 and movement to a second position that is out of the beam of
the x-rays
along the vector 110. Therefore, approximately 900 rotations per minute may be
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selected to achieve movement into and out of the beam at a rate to match the
switching
of the x-ray tube 100.
[0086]
With continuing reference to Fig. 5 and additional reference to Fig. 6,
the filter carrier assembly 350 may be connected to a carry gear 360, where
the filter
carrier assembly 350 is removed in Fig. 6 for clarity of the following
discussion. The
carry gear 360, in various embodiments, is driven by a belt 364 that is driven
by a drive
gear 366 that is connected to a shaft 370 powered by a motor assembly 374. The
motor assembly 374 may include a housing 376 and a powered motor (not
specifically
illustrated) within the housing 376. The motor assembly 374 may be powered by
various power mechanisms, such as electrical power, pneumatic power, or the
like.
The motor assembly 374 may be any appropriate motor assembly that can drive
the
filter carrier assembly 350 at the selected speed and be powered by the
imaging
system 16 and controlled by the controller 32. The motor assembly 374 may
include an
appropriate stepper and/or servo motors, for example the Maxon EC-I-40
brushless
DC servo motor sold by Maxon Motor Ag having a place of business in
Switzerland.
[0087]
Control connection 380 may be provided and interconnected with the
imaging system controller 32. As discussed above, the positioning of the
filter member
300 may be controlled by the imaging system controller 32 to filter x-ray
spectra, as
discussed above. The filter member carrier assembly 350 may be mounted to the
carry
gear 360 through the appropriate mechanism, such as one or more screws, bolts,
adhesives, rivets, or other appropriate mechanical or chemical adhesions of
the carrier
assembly 350 to the carry gear 360. Therefore, upon rotation of the drive gear
366 the
belt 364 may drive the carry gear 366 to spin the filter carrier assembly 350,
including
the filter member 300, at a selected rotation rate. It is understood, however,
that the
motor assembly 374 may be directly connected to the carry gear 360 without
requiring
the belt 364. In a direct connection, for example, the carry gear 360 may be
mounted
directly to the shaft 370 (e.g. replacing the drive gear 366) and/or the carry
gear 360
may directly engage the drive gear 366 without the belt 364 and/or other
transmission
system. Alternatively, other appropriate drive or transmission mechanisms may
be
provided between the drive gear 366 and the carry gear 360 such as a worm
drive, a
geared transmission, or other appropriate connection systems.
[0088]
During operation, the position of the filter member 300 may be synced
with the location of the beam 110 in time with the emission of the x-rays at
the selected
power that are intended or selected to pass through the filter member 300
before
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reaching the patient 14. According to various embodiments the filter assembly
200c
may include an encoder assembly 388. The encoder assembly 388 may include a
magnetic encoder that may include a sensing magnet portion 390 and a
transmitting
magnetic portion 392. The encoder assembly 388 may be positioned near or at
the
carrying gear 360 such that it is positioned at the location of the filter
member 300. For
example, the sending magnet portion 392 can be positioned at a location that
is
adjacent or near the filter member 300. Therefore, when the magnetic portion
392
passes the reading portion 390 an index signal may be transmitted that the
filter
member 300 is the location of the beam 110.
[0089] The
encoder assembly 388 may additionally and/or alternatively
include a magnetic encoder such as the RMB20 magnetic encoder module and
magnet sold by Renishaw having a place of business in West Dundee, Illinois,
U.S.A.
In such a system the magnetic encoder 388 may include a magnet 391 that is
incorporated into or in place of an axle to which the magnet 390 may be
otherwise
connected. The magnet 391 may rotate with the carrier gear 360 as the filter
member
300 rotates. As the magnet 391 rotates a magnetic field produced by the magnet
391
moves relative to an integrated circuit encoder assembly that may be included
on an
integrated circuit or printed circuit board assembly system 393 that is fixed
relative to
the carrier gear 360 and the magnet 391. As is understood by one skilled in
the art, the
integrated circuit system 393 can sense the moving magnetic field of the
magnet 391 to
determine the index signal as discussed herein. Therefore, the encoder
assembly 393
may act as the sending portion 392 or alternatively thereto. Accordingly, it
is
understood by one skilled in the art that the encoder assembly 388 may be
provided in
any appropriate format including the magnet 391 and encoder assembly 393 as a
noncontact magnetic encoder.
[0090]
During operation, the filter assembly 200c may be operated or
controlled such that the movement of the filter carrying member 310 is
constant and
synced in time to the emission of the selected x-rays along the x-ray beam
110. Direct
control of the motor assembly 374 with the image controller 32 can ensure that
the filter
member 300 is positioned in the beam of the selected time to filter the x-rays
emitted
from the x-ray tube 100.
[0091]
In an alternative and/or additional synchronizing method, the motor
assembly 374 may be powered to turn the filter carrier assembly 350 at a
nominal
speed such that the filter carrier assembly 350 may rotate at about 900 RPMs,
as
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discussed above. In various embodiments, a gear ratio between the motor
assembly
374 and the carrier gear 360 is 3:1, thus the motor may rotate at about 2700
RPMs to
cause rotation of the filter carrier assembly at about 900 RPMs.
[0092]
The encoder assembly 388 can be positioned and incorporated such
that a single pulse signal is provided as the carrier assembly 350 rotates on
the carrier
gear 360. The index impulse may be aligned with the position of the beam 110
in the
imaging system 16. Therefore, an indication or signal of when the filter
member 300 is
positioned in the beam 110 may be determined based upon an index pulse. To
ensure
that the filter member 300 is positioned at the beam 110 at the selected time,
a
synchronization process 400, as illustrated in Fig. 7, may occur once at start-
up of the
imaging system 16 or at a selected rate during imaging to ensure constant
synchronization. As discussed above, the controller 32 may include a memory
with a
predetermined imaging protocol (including timing of imaging, number of image
projections, etc.) and a related timing for operating the motor assembly 370
to move the
filter carrier assembly 350. Further, the synchronization process 400 may be
encoded
as instructions to be recalled from the memory and executed by the processor.
[0093]
Initially, the motor may be started in block 402 to initiate rotation of
the
filter carrier assembly 350 at the selected constant speed, such as about 900
RPMs.
After starting the motor and rotating the filter carrier assembly 350, an in-
position or
index pulse can be received by the controller 32 in block 404. The in-position
or index
pulse, as noted above, can occur as the sending portion 392 passes the
receiver
portion 390 at the location of the beam 110, thus signaling that the filter
member 300 is
in position relative to the beam 110 and would filter x-rays, if x-rays were
being emitted.
The signal from block 404 can then be compared with a selected x-ray exposure
signal
in block 408. As noted above, the x-ray exposure may switch between at least
two
energies in a dual energy system at a selected rate, such as about 30 Hz.
Therefore,
the in-position signal when the filter member 300 is in position relative to
the x-ray
beam 110 can be compared to the appropriate timing or frequency of the
selected x-ray
emission.
[0094] A
decision block of in sync" 410 can be used to determine whether
the filter member 300 is in sync with the selected x-ray emission timing and
signal by
the comparison in block 408. If it is determined in block 410 that the filter
member 300
is in sync, then a YES path 420 may be passed to end the synchronization
procedure in
END block 426. The speed of the movement, including rotation, of the filer
carrier
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assembly 350 may not change, therefore. Following the ending of the
synchronization
procedure 400, imaging may occur according to the selected imaging procedure,
such
as controlled by the controller 32, at the selected constant speed.
[0095]
If synchronization is determined to not have occurred, a NOT path 440
may be followed to a synchronization procedure 446. The synchronization
procedure
446 may include various steps such as determining a position offset in block
450. After
determining a position offset, a send command to change velocity in block 456
may be
made. The send command to change velocity in block 456 may be sent by the
imaging
system controller 32.
[0096] The
send command to change velocity may increase or otherwise
change the velocity of the carrier assembly 350 from the selected constant
speed. For
example, the speed may be increased from 900 RPMs to about 1000 RPMs, or about
2000 RPMs, or any selected speed. The velocity change may be for a selected
period
of time to correct for the position offset to achieve alignment or
synchronization of the
phase of the position of the filter member 300 with the timing of the emission
of the x-
rays. For example, the speed of the motor assembly 374 may be increased by a
selected amount to position the filter member 300 within the x-ray beam 110 at
the
timing signal or emission signal for the x-rays at the appropriate time.
[0097]
After a selected period of time, such as included in the send command
to change velocity command block 456, the velocity of the filter carrier
assembly 350
may be returned to the selected constant velocity, such as about 900 RPMs. The
method may then return to block 404 and an in position signal may again be
received
from block 404. A comparison to the emission timing signal in block 408 may
then
occur. Thus, the in sync determination of block 410 can be determined. If it
is
determined that the carrier assembly 350 remains out of sync, the NO path 440
can be
again used to attempt to achieve synchronization in block 446.
However, if
synchronization is determined, YES path 420 can be followed to the end block
426 and
the constant speed may be maintained. Thus, the synchronization process 400
may be
used in a loop to achieve synchronization of the position of the filter member
300 in the
beam 110 at the time of emission of x-rays.
[0098]
Accordingly, the motor assembly 374 may be operated to achieve
synchronized rotation of the carrier assembly 350 with timing of the x-ray
emission
without rigid and direct continuous control of the motor assembly via a
controller,
including the image controller 32. The motor assembly 374 may, therefore, be
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operated to position the filter member 300 and beam 110 at an appropriate time
using a
synchronization technique, including the synchronization method 400 discussed
above,
and rotating the filter carrier assembly 350 at a constant rate.
[0099]
Turning reference to FIG. 8, a filter assembly 200d may include a filter
carrier assembly 460. The filter carrier assembly 460 may be similar to the
filter carrier
assembly 350 of the filter assembly 200c illustrated in FIG. 5. Thus, the
filter carrier
assembly 460 may include a generally circular member having an outer curved
edge
464. The filter carrier assembly 460 may differ, however, by having a first
void 468
substantially opposed to a second void 472 at about 180 from each other
around an
axis of rotation 480. The filter carrier assembly 460 may also include two
filter
members including a first filter member 500 and a second filter member 504.
Each of
the filter members may be positioned about 180 apart around the axis of
rotation 480.
Further, the voids 468 and 472 may be positioned at generally 90 offset from
the filter
members 500 and 504 around the axis of rotation 480. The axis of rotation 480
may be
similar to the axis of rotation 330, as discussed above and illustrated in
FIG. 5, as the
carrier assembly 460 may be mounted on the carrier gear 360 of the drive
assembly
illustrated in FIG. 6. Accordingly, the filter carrier assembly 460 may
replace the filter
carrier assembly 350 discussed above.
[00100]
Accordingly, the filter carrier assembly 460 may alternatively include
a filter member and a void at 90 around the axis of rotation 480. The
operation of the
filter carrier assembly 460 may be similar to the filter carrier assembly 350,
as
discussed above. However, the positioning of two filter members about 180
from
another may allow the rotational speed of the filter carrier assembly 460 to
be about
one half that of filter carrier assembly 350. Accordingly the rotational speed
of the filter
carrier assembly 460 may be about 450 RPMs rather than about 900 RPMs. As one
skilled in the art will understand, the filter member 500 or 504 would be
positioned in
the beam line 110 at about twice the rate as a single filter member, such as a
single
filter member 300.
Therefore the filter member assembly 460 may rotate at
substantially half the speed of the filter member assembly 350.
[00101] However, the speed or frequency of operation of the filter carrier
assemblies 350 or 460 may be substantially constant during operation once a
selected
speed is reached. Therefore, as the carrier assemblies 350, 460 achieve the
appropriate operational speed the speed may be maintained and the filter
members will
be positioned into and out of the beam 110 at an appropriate time.
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[00102] Further, the synchronization of the filter carrier assembly 460 may
occur in a manner similar to that discussed above, such as by the
synchronization
method 400. An index signal may be received when one of the filter members
500, 504
is within or at an in position that intersects the beam vector 110. The
position of the
other filter member is substantially 180 from the indexed filter member,
therefore, the
synchronization will be achieved as the slower speed of the filter carrier 460
ensures
that the opposite filter member will reach the beam 110 at the appropriate
time even if
synchronization is made relative to only one of the filter members. Therefore,
the filter
carrier assembly 460 may be operated at a speed of substantially half that of
the filter
carrier assembly 350, while synchronization and a constant speed may still be
performed and maintained in the manner similar to that described above.
[00103] Accordingly, according to various embodiments, a filter member may
be positioned in the x-ray beam 110 to assist in achieving a selected spectra
to reach
the patient 14. Operation of the imaging system 16, therefore, may be used to
achieve
contrast enhancement of selected tissues or materials, such as two different
soft
tissues, hard tissue and soft tissue, contrast agent and other materials,
metal and bone,
or other selected differing materials. The filter member may be positioned
into and out
of the x-ray beam 110 according to various mechanisms, including those
discussed
above, to achieve further separation of the x-ray spectra at the differing
energies.
[00104] It will also be understood that the image data and/or model can be
used to plan or confirm a result of a procedure without requiring or using
navigation and
tracking. The image data can be acquired to assist in a procedure, such as an
implant
placement. Also, the image data can be used to identify blockages in the
vasculature
of the patient 14, such as with the contrast agent. Thus, navigation and
tracking are not
required to use the image data in a procedure.
[00105]
According to various embodiments, as discussed above, a filter
assembly may be included in a collimator 198 that may be positioned between
the x-ray
source 100 and the subject 14. As schematically illustrated in Fig. 2, and
discussed
above, the collimator 198 may include various features and portions, such as
the filter
200, according to various embodiments, as discussed above. With additional
reference
to Fig. 9, the collimator 198 may include filters, as discussed above, and
various other
portions or systems in addition to the filters, according to various
embodiments.
[00106]
As illustrated in Fig. 9, the collimator 198 may also include various
systems or features to selectively allow x-rays to pass through an exposure
opening
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600 of the collimator 198. The exposure opening 600 may be formed as a passage
through an exposure ring or exposure member 604. The exposure ring 604 may be
formed of a selected material, such a material that is opaque to x-rays.
Accordingly,
the exposure opening 600 may provide the only passage for x-rays out of the
collimator
198 towards the subject 14.
[00107]
The exposure ring 604 may be formed on a housing member 606
of the collimator 198. Generally, the housing member 606 may be part of a
housing
608 that encompasses moving portions of the collimator 198 and allows it to be
interconnected with various features, such as the x-ray source 100. The
collimator may
include the filter 200, such as the filter 200d, as discussed above. Further,
the
collimator 198 may be mounted on the housing 608 which, in turn, is mounted to
the x-
ray source 100.
[00108]
In various embodiments, the collimator 198 can include various
portions to allow altering a size or shape of the x-ray beam or cone 108. For
example,
the exposure opening 600 may include a maximum dimension of the x-rays that
may
exit the collimator 198, such as 3 cm x 3 cm. Various radio opaque leaves,
however,
that form an axis selection assembly may be moved relative to the exposure
opening
600 to alter the size of a cone of x-rays that will pass through the exposure
opening 600
and, also may position the x-ray beam relative to the exposure opening 600.
[00109] With
continuing reference to Fig. 9 and additional reference to Fig.
10A and Fig. 10B, an axis selection assembly (ASA) 626a, according to various
embodiments is illustrated. The ASA 626a is positioned within the housing 608
of the
collimator 198. The ASA 626a may include one or more leaves that are
configured to
move relative to the exposure opening 600 to select a size and/or location of
a selected
opening 630 to be formed relative to the exposure opening 600. The selected
opening
630 is an opening through which the x-rays from the x-ray beam 108 is allowed
to pass
before exposing the subject 14. The selected opening 630 may be formed before
or
after the x-ray beam has passed other selected filters or axes, such as the
high speed
filter 200c.
[00110] The
ASA 626a that includes a plurality of leaves that are able to
move relative to one another on respective X-axis and Y-axis of movement
relative to
the exposure opening 600. For example, as illustrated in Fig. 10A, a first
leaf 640a and
a second leaf 640b may move opposed to each other and move in an X-axis
generally
in the direction of the double-headed arrow 646. A further pair of leaves may
include a
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third leaf 650a and a fourth leaf 650b that may move in a Y-axis generally in
the
direction of the double-headed arrow 656. Accordingly, the leaves 640 and 650
may
move relative and/or perpendicular to one another to form the selected opening
630
relative to the collimator exposure opening 600.
[00111] The
selected opening 630 may be formed in substantially any
location relative to the exposure opening 600 by selectively moving the leaves
640, 650
relative to one another. Movement of the leaves, discussed further herein, may
be
based upon instructions that may be stored in a memory 33b that may
communicate
through various communication systems, such as wired, wireless, physical
media, or
the like, by the controller 32 to transmit instructions to move the leaves
640, 650. By
moving the leaves, it is understood that the selected opening 630 may be
formed in
selected shapes, selected sizes, and selected positions relative to the
exposure
opening 600. Therefore, it is understood that the selected opening 630, as
illustrated in
Figs. 10A and 10B, is merely exemplary and not intended to limit the possible
selected
openings.
[00112]
Each of the leaves 640, 650 may be formed of a selected material,
such as a high Z material (e.g. a material with a high effective Z number or
high atomic
number). For example, the leaves may be formed of lead of a selected
thickness. The
leaves may be formed so that the detector substantially only receives or
detects x-rays
that pass through the selected opening 630. Therefore, the leaves 640 and 650
may
be moved to selectively create the selected opening 630 at a selected size and
position
for exposing the subject 14 to x-rays from the source 100.
[00113]
The ASA 626a, including the leaves 640, 650, may include a frame
portion 660. The frame 660 may be formed as a single piece, or formed as a
plurality
of pieces. The frame 660, for example, may be formed as a single cast piece or
member onto which the selected portions of the leaves and other elements are
positioned. Alternatively, or in addition to a single member, various pieces
may be
interconnected such as with welding, raising, or other fasteners. Additional
brackets or
fixation points may be included with the frame 660, as discussed herein.
[00114]
Mounted to the frame 660 may be guide rails that assist in guiding
the leaves 640, 650. For example, the X-axis leaves 640 may be interconnected
with a
first rail 668 and a second rail 670. The rails 668, 670 may be fixed to the
frame 660 in
a selected manner, such as with rivets, threaded screws, or the like. Further,
the rails
668, 670 may be substantially parallel to one another. The rails 668, 670
allow the
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leaves 640 to move relative to one another substantially binding free and in a
single
plane. Further, the rails 668, 670 assist in maintaining straight and linear
movement of
the leaves 640.
[00115]
The two leaves 640a, 640b may be fixed or mounted to leaf
carriers 674a and 674b. Each of the carriers 674 may have fixed thereto one of
the
respective leaves 640a, 640b. Fixation of the leaves to the respective carrier
674 may
be with braising, rivets, or other appropriate fixation mechanisms. The
carriers 674a,
674b may extend to cars or sliding members 680a, 680b, 680c, 680d. Each of the
carriers 674a, 674b may be fixed to two of the cars that are able to move on
the rails
668, 670. As the carriers 674a, 674b move, the cars 680a-d may move along the
respective rails 668, 670 and the carried leaves 640a, 640b may move generally
in the
direction of the double-headed arrow 646. The parallel rails 668, 670 allow
for smooth
and binding free movement of the leaves 674a, 674b relative to one another,
and the
frame 660. Further, the parallel rails 668, 670 allow for a driving mechanism
690 on a
single end, and in various embodiments only the single end, of the carriers
674a, 674b
and/or leaves, as illustrated in Figs. 10A and 10B.
[00116]
The drive mechanism 690 may include various portions such as a
motor assembly 692, a sensor assembly, such as a position sensor 694, and a
double
lead screw assembly 700. The drive mechanism 690 may operate and be controlled
by
the controller 32 with a selected communication system 701 that may be
provided to
control the motor 692 of the drive mechanism 690 from the controller 32 and
the
communication system may receive sensed positions from the sensor 694.
Further, the
controller 32 may be operated by a user to selectively operate the motor 692
for various
purposes during imaging of the subject. Therefore, the drive mechanism 690 to
move
the leaves 640a and 640b may be operated in an automatic manner based upon
predetermined instructions, to form the selected opening 630, manually by a
user such
as during an imaging procedure, or a combination of both.
[00117]
The motor 692 may be any appropriate type of motor such as a
stepper motor, servo motor, or other appropriate type of motor. Generally, the
motor
692 provides rotary motion to a drive shaft 704 which is connected to the
screw
assembly 700. The motor 692 may be mounted to a bracket 706 that may be fixed
to
the frame 660 or may be directly fixed to the frame 660. A connection portion,
such as
a split nut 708 may be used to connect to the drive shaft 704 to the screw
assembly
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700. The screw assembly 700 may further include a second split nut 710 that
connects
a first screw portion 712 to a second screw portion 715.
[00118]
The first screw portion 712 may threadably engage a carrier holder
714. The carrier holder 714 may be fixed to a bracket or extension 716 of the
leaf
carrier 674b. The carrier holder 714 may be fixed to the bracket 716 in the
appropriate
manner, such as with one or more screws 714a. The screws 714a, however, may
also
be provided or included as rivets, nuts, or other appropriate connection
mechanisms.
[00119]
The carrier holder 714 may include an internal thread that is
threaded in a first direction. Therefore, as the first screw portion 712
rotates within the
carrier holder 714 an external thread on the first screw portion 712 may
engage internal
threads on the carrier holder 714 to move the leaf carrier 674b generally in
the direction
of the double-headed arrow 646.
[00120]
The second screw section 715 may also include an external
thread. The second screw section 715, connected to the first screw portion 712
through the split nut 710, receives a rotational force from the motor 692 via
the first
screw section 712. A second carrier holder 720 may include an internal thread
that is in
an opposite direction of the internal thread of the first carrier holder 714.
Therefore, the
first leaf carrier 674a may move opposite the direction of the second leaf
carrier 674b,
although the screw portions 712, 715 are rotating in the same direction.
[00121] The
second carrier holder 720 may be fixed to a second extension
or bracket portion 722 that extends from the carrier 674a. The second carrier
holder
720 may be fixed to the extension 722 with one or more screws 724 similar to
the screw
714a. The sensor 694 may sense motion or rotation of the screw portion 712,
715 to
assist in determining the position of the leaves 640. The sensor 694 may be
connected
to the second screw portion 715 with a third split nut 728. The position
sensor 694 may
be any appropriate positions sensor, such as an optical shaft encoder
including the US
Digital 54T optical shaft encoder (Part No. 54T-300-125-D-B) sold by US
Digital,
having a place of business in Vancouver, WA, USA.
[00122]
With continued reference to Fig. 10A and additional reference to
Fig. 10B, the leaves 650a and 650b may be moved in the direction of the double-
headed arrow 656 on the Y-axis in a manner substantially similar to the leaves
640a
and 640b. The two leaves 650a, 650b may be connected, individually, to two
leaf
carriers 780a, 780b, in a manner similar to the leaves 640 connected to the
leaf carriers
674, as discussed above.
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[00123]
The leaves 650 may be driven with a drive mechanism 750 similar
to the drive mechanism 690, discussed above. A communication system 752 may
connect a motor 758 and a position sensor 760 of the drive mechanism 750 with
the
controller 32. The controller 32, therefore, may operate or control both the
motor 692 of
the drive mechanism 690 and the motor 758 of the drive mechanism 750.
Operation of
the drive mechanism 750 is similar to the operation of the drive mechanism
690,
therefore, its operation in part will not be discussed in detail, but
disclosed briefly here
with reference to Fig. 10B.
[00124]
The drive mechanism 750 may include the motor 758, a sensor
760, and a lead screw mechanism 764. Therefore, the motor 758 may be fixed to
a
bracket 766 which is fixed to the frame 660 and/or fixed directly to the frame
660. A
drive shaft 770 may be driven by the motor 758 which is connected to a first
screw
portion 774 by a split nut 776. The first screw portion 774 passes through a
third carrier
holder 778 to threadably engage the third carrier holder 778. The third
carrier holder
778 has internal threads in a first direction to move the leaf carrier 780a to
which the
leaf 650b is connected. The leaf carrier 780a may include an extension 780b to
which
the third carrier holder 778 is connected such as with one or more screws 784.
Further,
the leaf carrier 780a may extend and interconnect with a car 782 that rides on
a third
rail 786. The leaf carrier 780a also extends to a car 782b that rides on a
fourth rail 788.
The rails 786, 788 may be substantially parallel similar to the rails 668,
672, discussed
above, to allow for smooth and non-binding movement of the leaf 650b with the
drive
mechanism 750 at a single end, and in various embodiments only the single end,
of the
leaf 650b.
[00125]
The first screw portion 774 is connected to a second screw portion
794 with a split nut 796. Other connections, either in addition or
alternatively to the split
nut 796 may be used, such as welding, adhesive materials, brazing, etc.
Therefore,
rotational motion of the first screw portion 774 is transferred to the second
screw
portion 794. The second screw portion includes external threads which engage
internal
threads in a fourth carrier holder 800. The internal threads in the fourth
carrier holder
800 may be opposite those in the internal threads of the third carrier holder
778. The
first and second screw portions 774 and 794 may have similar threads and an
identical
rotational direction of the screw portions 774, 794 will move the respective
carrier
holders 778 and 800 in opposite directions.
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[00126]
The fourth carrier holder 800 may be fixed to the fourth leaf carrier
780b through an extension or projection 804 with one or more screws or other
fixation
members 806, similar to the fixation members discussed above. The leaf carrier
780b
may include portions that extend and connect to two cars 782c and 782d so that
the
leaf carrier 780b may ride along the rails 788 and 786 generally in the
direction of
double-headed arrow 656 in the Y axis. As discussed above, the rails 786, 788
assist
in allowing movement of the leaf 650a in a smoothing, straight, and non-
binding
manner.
[00127]
It is understood the drive mechanisms 690 and 750 may be
provided at the single ends, and in various embodiments only single ends, of
the
respective leaves 640, 650 and through the interaction of the leaf carriers
674, 780 with
the respective parallel rails 668, 670, 786 and 788, allow smooth and non-
binding
movement of the leaves 640, 650. It is further understood, however, that drive
mechanisms may be provided at both ends of the respective leaf carriers to
simultaneously drive both ends of the leaf carrier to assist in moving the
leaves 640,
650 to selected positions and at a selected rate. In either instance, the
leaves 640a,
640b may move at a similar or identical speed based on each other. Similarly,
the
leaves 650a, 650b may move at a similar or identical speed based on each
other.
Thus, the selected aperture 630 may be increased or decreased in size, but
have a
center 630a of the selected exposure be substantially unmoved regardless of
size or
shape of the selected aperture 630. Accordingly, the selected aperture 630 may
be a
square that is 1 inch by 1 inch that has the center 630a or the selected
aperture 630
may be a rectangle that is 1 inch by 2 inches and would still maintain the
center 630a.
[00128]
In various embodiments, individual drive mechanisms, similar to
the drive mechanism 690 or the drive mechanism 750, and may include drive
mechanisms 691 and 751 (shown in phantom) may be connected individually to
each of
the leaves 640a, 640b, 650a, and 650b. Thus, each drive mechanism 690, 691,
750,
751 may be used to drive the respective individually each leaf 640a, 640b,
650a, and
650b on the respective X-axis or Y-axis. Each drive mechanism may connect or
interact with a single leaf connector to engage and move the respective leaf.
As each
leaf 640a, 640b, 650a, and 650b moves independently, as operated by the
controller
32, the selected opening 630 may have an independent size and the center 630a
may
move relative to the frame 660. Thus, it is understood that each of the
individual leaves
640a, 640b, 650a, and 650b may be driven separately, in a manner similar to
that
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described above, with an appropriate drive mechanism to select all of a shape
and size
of the selected opening 630 and a location of the center 630a, such as an
alternative
center location 630a'.
[00129]
Accordingly, the ASA 626a may be positioned in the collimator 198
to form the selected exposure opening or aperture 630. The ASA 626a may be
incorporated into the collimator 198 in any appropriate manner, including as
illustrated
in Fig. 9 as discussed above. It is understood, however, that the leaves that
form the
ASA may be moved in an appropriate manner including those discussed further
herein.
[00130]
In various embodiments, with reference to Fig. 11, the collimator
198 may include an ASA 626b that may include a stage or platform member 1620
which may include a stage exposure opening or passage 1624. The stage exposure
opening 1624 may also be fixed in dimension by walls or edges through the
stage
1620. The stage exposure opening 1624 may be of a selected size relative to
the
exposure opening 600, such as larger, smaller, or the same size. The stage
exposure
opening 1624 may be larger than the exposure opening 600 in various
embodiments to
ensure that all of the exposure opening 600 may be exposed to x-rays, if
selected.
[00131]
The ASA 626b may be provided in various embodiments, as
discussed herein, to selectively size and position an opening formed by leaves
relative
to the stage exposure opening 1624. Thus, the stage exposure opening 1624 may
define a maximum and/or fixed opening through the stage 1620 that may be
altered by
the ASA 626b. It is understood, however, that the stage 1620 may not include a
small
opening, but may include only an open or external frame (similar to the frame
660
discussed above) to which other portions are connected, as discussed herein.
[00132]
In various embodiments, the ASA 626b includes a plurality of
leaves, including a first leaf 1630, a second leaf 1632, a third leaf 1634,
and a fourth
leaf 1636. Each pair of the leaves, such as a first pair of leaves 1630, 1632
and a
second pair of leaves 1634, 1636 may operate to adjust the beam of x-rays
passing
through the stage exposure 1624 in a X and/or Y axis. For example, the first
pair of
leaves 1630 and 1632 may move in an X-axis to change the beam of x-rays in the
X
axis while the second pair of leaves 1634, 1636 may move in a Y-axis to adjust
the
beam of x-rays through the exposure passage 1624 in a Y axis direction. As
discussed
further herein, the leaves 1630, 1632, 1634, 1636 may be operated to adjust a
size, a
position, or an orientation of a x-ray's beam passage through the exposure
passage
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1624, as selected by a user, programming of the x-ray exposure, selected
energy of the
x-ray beam, or the like.
[00133]
Each of the leaves 1630, 1632, 1634, 1636 may be moved by a
selected mechanism. For example, each leaf may be interconnected with a linear
motor, similar to the linear motor 270 discussed above. For example, the first
leaf 1630
may be interconnected with a first linear motor 1650, the second leaf 1632 may
be
interconnected with a second linear motor 1652, the third leaf 1634 may be
interconnected with a third linear motor 1654, and the fourth leaf 1636 may be
interconnected with a fourth linear motor 1656. Each of the linear motors
1650, 1652,
1654, and 1656 may be operated in a manner similar to the linear motor 270
discussed
above to move the respective leaves 1630-1636 relative to the stage exposure
passage
1624.
[00134]
The linear motors 1650-1654 may be controlled by the control
system 32 of the imaging system 16; the controller may include the processor
33a that
is designed and/or configured to operate the linear motors 1650-1654 and/or
execute
instruction, such instructions stored on the memory system 33b. Each of the
motors
1650-1656 may be individually connected through various communication lines,
such
as the respective communication lines 1658, 1660, 1662, and 1664. It is also
understood that a communication system may be incorporated into the collimator
198 to
communicate with the controller 32. The communication system may include
various
wireless communication protocols that may be used to wirelessly communicate
with the
controller 32 to operate the motors 1650-1656. As discussed herein, each of
the
motors 1650-1656 may be operated independently of one another to move the
respective leaves 1630-1636 relative to the platform exposure 1624. It is
further
understood, however, that the respective motors may be operated as motor
pairs. For
example, the first motor 1650 and second motor 1652 may be operated as a pair
to
move the respective leaves 1630, 1632 relative to the passage 1624 while the
third and
fourth motors 1654, 1656 may be operated as a pair to move the respective
leaves
1634, 1636 relative to the exposure passage 1624. When operated as a motor
pair, a
single signal may be sent to adjust a respective axis of the collimator (e.g.,
X axis or Y
axis). The single signal may be to adjust the position (e.g., +2mm). The motor
pair
may then operate both motors to achieve the adjustment. Generally, the motors
1650-
1656 are operated to move respective leaves to and away from one another as a
pair
or as the group of four leaves 1630-1636.
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[00135]
With brief discussion of the first leaf 1630 and the first motor 1650,
it is understood that the other leaves and motors may be configured
substantially
similar to the leaf 1630 and motor 1650 and will not be repeated in detail
below.
Generally, the leaf 1630 may be formed of a selected material that may be
substantially
radio opaque. That is, the leaf 1630 may be provided or formed of a material
that will
not allow x-rays to penetrate or substantially penetrate the leaf 1630 to
expose the x-
ray detector through the patient 14. For example, the leaf 1630 may be formed
of lead
having a selected thickness. Any appropriate high Z material, however, may be
selected to form the leaf 1630. The leaf 1630 may be formed of a material in a
selected
dimension such that its mass may be moved at a selected rate by the motor 1650
relative to the exposure opening 1624.
[00136]
The leaf 1630 may be positioned in a leaf carrier 1670 of the first
motor 1650. The leaf carrier 1670 may include a first finger 1672 and a second
finger
1674 that extend from a main carrier body 1676. The first and second fingers
1672,
1674 may define an opening or passage therethrough and the leaf 1630 may be
positioned between the two fingers 1672, 1674 in the passage. The leaf 1630
may be
fixed within the passage relative to the fingers 1672, 1674 in any appropriate
manner
such as with brazing, an adhesive, a mechanical fixator (e.g., a screw), or
other
appropriate mechanism.
[00137] The
leaf carrier 1670 may be mounted to a moving magnet 1680.
The moving magnet 1680 may be positioned over a stationary and/or linear motor
coil
1682. As discussed above, the stationary linear motor coil 1682 (similar to
the
stationary linear motor coil 274 discussed above) may be operated to move the
moving
magnet 1680 (similar to the magnet 276, discussed above). It is further
understood that
various other configurations may be provided, such as a stationary magnet and
moving
linear motor coil or the like. Thus, the leaf carrier 1670 may be mounted to a
moving
coil that is moved relative to a fixed magnet.
[00138]
The leaf carrier 1670 may be fixed to the moving magnet 1680 with
various mechanisms. For example, a screw or rivet may be positioned through a
fixation passage 1686 to fix the carrier 1670 to the magnet 1680. It is
further
understood that various pieces, welding, brazing, or the like may be used to
fix the leaf
carrier 1670 to the moving magnet 1680.
[00139]
Further, the linear motor 1650 may include linear bearings 1690 on
which the carrier 1670 moves. The linear bearings 1690 may bear the carrier
1670 and
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the attached moving magnet 1680 as they move. The bearings 1690 may also
assist in
directing movement of the linear motor 1650. Generally, the bearings 1690 may
limit a
movement of the moving magnet 1680, such as generally in the direction of the
double-
headed arrow 1694. The double-headed arrow 1694 may be along the X-axis, as
discussed above, to move the leaf 1630 on the X-axis. A position of the
carrier 1670
may be determined with a position determining system 1700 including a read
head
1702 and a rail 1704. The read head 1702 may read a relative or absolute
position of
the carrier 1670 relative to the rail 1704, similar to operation of the read
head 292 and
the rail 294, as discussed above.
[00140]
Accordingly, the operation of the linear motor 1650 to move the leaf
1630 may be similar to operation of movement of the linear motor 270 to move
the filter
260. In particular, the leaf 1630 may be moved to be positioned into or out of
at least a
portion of the x-ray beam 108 moving along the vector path 110. As discussed
further
herein, the leaf 1630 may be used or operated to block at least a portion of
the full
emission of x-rays from the x-ray source 100 to configure or shape the beam
passing
through the platform exposure passage 1624.
[00141]
As discussed above, each of the leaves 1630, 1632, 1634, and
1636 may be moved as respective pairs and/or moved independently to achieve a
selected opening position and/or shape to allow x-rays to pass through the
platform
exposure passage 1624. As illustrated in Fig. 11, the leaves 1632 and 1630 may
be
the leaves that define the X axis position of a selected opening 1720. The
leaves 1634,
1636 may be moved to change a Y axis position of the opening. As illustrated
in Fig.
11, a shape of the selected opening 1720 is defined by all of the leaves 1630,
1632,
1634, and 1636.
[00142] As
illustrated in Fig. 11, to allow for each one of the leaves 1630-
1634 to move relative to one another, the opposing sets of the leaves may be
offset a
height relative to the other leaves. As illustrated, the pair of leaves 1630
and 1632 that
move in the X-axis may be positioned further away from the stage 1620 than the
opposed leaves 1634 and 1636 that may be positioned closer to the stage 1620
than
the X axis leaves 1630, 1632. The positioning of the Y axis leaves 1634, 1636
closer to
the stage 1620 may include forming an offset in the leaf carrier 1670c, 1670d
to
position them closer to the stage 1620 than the X axis leaves 1630, 1632.
Alternatively,
the X axis carrier 1670a and 1670d may be offset relative to the Y axis leaf
carriers
1670c, 1670d. Regardless of the configuration, the leaves opposing one another
to
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form the X and Y axis may be configured to allow them to move and be
positioned
simultaneously over at least a portion of the stage axis exposure 1624, as
illustrated in
Fig. 11.
[00143]
Similar to the selected opening 630, discussed above, the selected
opening 1720 may be any selected shape that may be defined by the leaves 1630-
1636. Each of the leaves 1630-1636 may be moved independently and individual,
similar to the leaves 640a, 640b, 650a, and 650b discussed above, for the
selected
opening 1720 to be selected to be square, rectangular, or other shape
depending upon
the geometry of the respective leaves 1630-1636. Further, the size of the
selected
opening 1720 may be selected based upon the relative position of the leaves
1630-
1636.
[00144]
Moreover, the position of the selected opening 1720, or a center
1720a of the selected opening 1720, may be selected also based upon the
position of
the leaves 1630-1636 relative to the stage exposure openings 1624. For
example, the
stage exposure opening 1624 may be a square, and the selected opening 1720,
and/or
the center 1720a, may be selectively positioned in a quadrant of the stage
exposure
opening 1624 such as a lower right quadrant. Further, however, the selected
opening
may be positioned in an upper left quadrant, as illustrated in phantom 1720'
by moving
the leaves 1630-1636 to form the selected opening 1720'. Thus, the selected
opening
1720' may be a center 1720a' different than the center 1720a of the selected
opening
1720. Further, the positioning of the leaves 1630-1636 relative to the stage
exposure
opening 1624 may selectively make the selected opening 1720 equal to the
dimensions
of the stage exposure 1624 or less than the full opening dimensions of the
stage
exposure opening 1624.
[00145] As
discussed above, each of the leaves 1630-1636 may be moved
by respective motors 1650-1656. The position of the leaf carrier 1670, for
example
carrying the leaf 1630, may be determined with the read head 1702 relative to
the rail
1704. As discussed above, the position of the read head 1702 relative to the
rail 1704
may be used to determine the position of the lead carrier 1670 in the manner
similar to
the determining of the position of the linear letter with read head 292
relative to the rail
294, as discussed above.
[00146]
Each of the leaves may be held by respective leaf carriers
including a leaf carrier 1670b to carry leaf 1632, leaf carrier 1670c to carry
leaf 1634,
and leaf carrier 1670d to carry leaf 1636. Each of the leaf carriers 1670a-
1670d may
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have respective read heads 1702a ¨ 1702d that are fixed to the leaf carriers
1670a-
1670d and move relative to respective rails 1704a-1704d. Communication line or
system (e.g., either wired connections and/or wireless connections) 1658-1664
may
communicate with a controller 32 to provide instructions to the linear motor
1650-1656
based upon the determined position of the leaf carriers 1670a-1670d based upon
the
read positions of the read heads 1702a-1702d relative to the rails 1704a-
1704d.
[00147]
The movement of the leaf carriers 1670a-1670d to move the
respective leaves 1630-1636 may be based upon a predetermined program or set
of
instructions that are recalled from the memory 33b. It is further understood
that the
memory 33b may include instructions to determine a planned or selected
movements
for forming the selected exposure opening 1720 based upon instructions input
by a
user. Instructions input by a user may be selected or changed during a
procedure
based upon various aspects, such as experience of the user, expertise of the
user, or
other selected considerations. It is understood, however, that the movement of
the
selected opening 1720 may be predefined and varied relative to the stage
exposure
1624 based upon a preselected positioning of the selected opening 1720.
Further,
given the four separate motors, each of the leaves may be moved independently
(e.g.
regarding direction along the respective X- and Y- axes and amount of
movement) in
the ASA 626b.
[00148]
Further, as discussed above, the collimator 198 may be included in
the imaging system 16. The imaging system 16 may include the source unit 36
that is
able or configured to move relative to a selected gantry, such as the imaging
gantry 34.
Therefore, as the source unit 36 moves relative to the gantry 34 and/or
relative to the
subject 14, the size, shape, and position of the selected opening 1720
relative to the
stage 1620 may change. The instructions stored in the memory 33b may be used
to
move the selected opening 1720 relative to the stage 1620 as the source unit
36 moves
relative to the gantry 34. Moreover, the controller 32 may receive feedback
from the
respective read heads 1702a-1702d to determine the position of the leaves 1630-
1636
to determine further and/or appropriate movements of the motors 1650-1656 to
position
the respective leaves 1630-1636 to form the selected opening 1720 of a
selected size
and/or position.
[00149]
The leaves 1630-1636, as illustrated in Fig. 11, are positioned to
move from one side of the stage aperture 1624 and an edge of the stage 1620.
Each
of the motors 1650-1656 have portions (e.g. motor coils) fixed on a single
side of the
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stage aperture and move the respective leaf carriers 1670a-1670d from the one
side
towards and over the stage aperture. Generally, as illustrated in Fig. 11, the
leaves
1630-1636 may not extend across the stage 1620 from one side to another. It is
understood, however, that at least one of the leaves 1630-1636 may extend
across the
stage 1620.
[00150]
With reference to Fig. 12, an ASA 626c is illustrated. The ASA
626c may include components of both of the ASA 626a and the ASA 626b, as
discussed above and illustrated in Figs. 9-11. The ASA 626c includes the
leaves 640'
and 650', similar to the ASA 626a. In the ASA 626c, however, the leaves 640',
650' are
moved with linear motors (as discussed herein) similar to the linear motors
discussed in
the ASA 626b. Rather than providing the drive mechanisms 690 and 750, as
discussed
above in the ASA 626a, linear motors are provided to drive the leaves 640',
650'.
[00151]
The leaves 640', 650' may be on leaf carriers 674, 780 as
discussed above, or may be directly connected to respective pairs of parallel
rails.
Regardless, each one of the leaves may be interconnected with a separate
linear motor
to individually move each of the leaves. Each leaf may be interconnected with
a single
linear motor drive mechanism and the respective pairs of rails to allow for
non-binding
and smooth movement of the leaves.
[00152]
As noted above, the ASA 626c may include portions similar or
identical to the ASA 626a. With reference to Fig. 12, the ASA 626c may be
mounted to
the stage 1620. The ASA 626c may include the leaves 640'a and 640'b that may
move
generally in the direction of double headed arrow 646 along the X axis. As
illustrated in
Fig. 12, the leaves 640', at only one end or at both ends, may be directly
connected to a
linear motor drive mechanism 1760. It is understood, however, that the leaves
640'
may be connected to leaf carriers (not illustrated in Fig. 12) similar to leaf
carriers 674
discussed above. The ASA 626c further includes two leaves 650'a and 650'b. The
leaves 650' may be directly connected to a second linear drive mechanism 1766,
at
only one or at both ends, to move the leaves 650 generally in the direction of
double
headed arrow 656 in the Y axis. It is understood, however, that the leaves
650' may
also be connected to leaf carriers such, as the carriers 780, as discussed
above for the
ASA 626a. As illustrated in Fig. 12, and further discussed further herein,
however, it is
understood that leaf carriers are not required and that the leaves 640', 650'
may be
directly connected to the linear drive mechanisms 1760 and 1766.
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[00153]
As illustrated in Fig. 12, the leaves 640' and 650' may be moved
relative to the stage 1620 to form the selected opening 630. The leaves 640',
650' are
connected with the respective drive mechanisms 1760, 1766 at only one end or a
single
end of the respective leaves 640', 650'. In various embodiments, drive
mechanisms
may be provided at both ends, if selected. Various bearing and/or rail systems
assist in
ensuring smoothing and binding free movement of the leaves 640', 650',
particularly
with the linear motor drive mechanisms connected to only one end of the leaves
640',
650'. Similarly, the drive mechanisms 1760, 1766 may be connected to only one
end of
the leaves 640', 650', similar to the connection of the ASA 626a.
[00154] The
first leaf 640'a is connected to a first moving coil 1770. The
moving coil may be fixed to the leaf 640'a in any appropriate manner such as
with an
adhesive, welding, or fastener (e.g., rivet, screw, or the like) or other
appropriate
connection mechanism. The second leaf 640'b is connected to a second moving
coil
1772 in a manner similar to the moving coil 1770 connected to the leaf 640'a.
Both of
the moving coils 1770, 1772 move along a common magnet 1774. The common
magnet 1774 forms a common portion for the drive mechanism 1760 and forms a
linear
motor with respect to both of the moving coils 1770, 1772. The linear motor of
the
drive mechanism 1760 may operate in a manner similar to that of the linear
motors (e.g.
1650, 1652, 1654,1656 as discussed above. The moving coils 1770, 1772 of the
linear
motor drive mechanism 1760 may move each of the respective leaves 640'a and
640'b
in the direction of the double headed arrow 646. The respective moving coils
1770 and
1772 are connected with the controller 32 with an appropriate communication
system
1770a and 1772a, respectively. The controller 32 may operate the linear motor
drive
mechanism 1760 to move the leaves 640' in the X axis to position and size the
selected
opening 630 in the X axis. The controller 32 may be manually operated or may
execute
instructions using the processor 33a based on instructions saved and recalled
from the
memory 33b.
[00155]
The position of the leaves 640'a and 640'b may be determined with
a position sensor 1776, similar to the positions sensors 290 discussed above.
The
position sensor 1776 includes a linear or elongated sensor 1778 and a first
read head
1780 fixedly connected to the moving coil 1770 and/or the leaf 640'a to move
relative to
the sensor 1778. A second read head 1782 is fixedly connected to the second
moving
coil 1772 and/or the second leaf 640'b to move relative to the sensor 1778. As
discussed above, the respective read heads 1780, 1782 may be connected via the
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respective communication systems 1770a and 1772a with the controller 32 such
that a
position signal may be transmitted to the controller 32 and the controller 32
may be
operated to control the drive mechanism 1760 based upon the position signal
from the
position sensor 1776.
[00156]
Further, the leaves 640' may be interconnected with bearings or a
pair of parallel rails 1784a and 1784b. The leaves 640'a, 640'b may be
directly
connected to the rails 1784 and/or interconnected with respective cars or
bearing trucks
1786a, 1786b, 1786c, 1786d. Therefore, the leaves 640' may move in a path
defined
by the rails 1784 along the X-axis. Further, the interconnection of the leaves
640' with
the rails 1784 allows for substantially smooth and non-binding motion in the X-
axis.
[00157]
The leaves 640', configured to move in the X-axis, may be offset a
distance from a surface 1621 of the stage 1620 greater than a distance of the
leaves
650'. As discussed further herein, the leaves 650' may move in the Y-axis
which may
be substantially perpendicular to the X axis. Therefore, to have non-
interfering
movement of the leaves 640' in the X axis and the leaves 650' in the Y axis,
the leaves
may be positioned in different planes so as to not contact one another to
allow for ease
of movement of the respective leaves.
[00158]
The leaves 650' are connected with the drive mechanism 1766 at
one end of the leaves 650'. Similar to the leaves 640', the leaf 650'a is
fixedly
connected to a third moving coil 1790 and the fourth leaf 650'b is fixedly
connected to a
fourth moving coil 1792. The third and fourth moving coils 1790, 1792 move
along a
single and common magnet 1794 to form the linear motor drive mechanism 1766.
Again, each of the moving coils 1790, 1792 are connected with the controller
32 with
respective and appropriate communication systems 1792a and 1790a. Again, it is
understood that the communication systems 1770a, 1772a, 1790a, and 1792a may
be
wired communication systems, wireless communication systems, physical media
transmission systems, or other appropriate communication systems. The
controller 32
may operate the drive mechanism 1766 to move the leaves 650' in a manner
similar to
that described above to operate a linear motor.
[00159]
Further, the controller 32 may receive position signals from a
position sensor 1796 associated with the drive system 1766. The position
sensor 1796
may include a single scale sensor 1798. A third read head 1800 may be fixed to
the
moving coil 1790 and/or the third leaf 650'a. A fourth read head 1802 may be
fixed to
the fourth moving coil 1792 and/or the fourth leaf 650'b. Both of the read
heads 1800,
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1802 may move along the sensor 1798 to provide a common reference position
sense
and position signal for the drive system 1766. The position signal may be
transmitted
to the controller 32 with the respective communication systems 1790a and
1792a. The
controller 32, therefore, may know or determine the position of the leaves
650'a and
650'b with the position signal from the position sensor 1796.
[00160]
The drive mechanism 1766 is connected to one end of the leaves
650'. The leaves 650', however, may be interconnected with a bearing system
including a third rail 1804a and a fourth rail 1804b. The rails 1804a, 1804b
may form a
second pair of rails or bearings that is substantially perpendicular to the
bearing rails
1784a, 1784b. The leaves 650' may directly engage the rails 1804 and/or may be
connected with cars or moving bearings or trucks 1806a, 1806b, 1806, and
1806d.
Regardless, the rails 1804 allow for substantially smooth and non-binding
movement of
the leaves 650'.
[00161]
The ASA 626c, therefore, may include leaves substantially similar
or identical leaves to the 640, 650 of the ASA 626a and drive mechanisms
similar to the
drive mechanisms of the ASA 626b. The leaves 640', 650' of the ASA 626c may be
moved to form the selected opening 630 in a manner similar to the leaves 640,
650 of
the ASA 626a with the alternative motors or drive mechanisms 1760 and 1766.
The
leaves 640', 650' may, as illustrated in Fig. 12, extend from one side of the
stage 1620
to a second side of the stage 1620 and may cross the stage aperture 1624. For
example, the rails of the rail pairs 1784, 1804 are spaced across the stage
aperture
1624 from one another. Thus, the leaves 640', 650' may span or cross the stage
1620.
Further, the leaves 640', 650' may be interconnected with moving magnets
rather than
moving coils, as discussed above. Accordingly, it is understood, that the ASA
626c
may be controlled with instructions to form the selected opening 630 similar
to the
manner of the ASA 626a as discussed above. It is further understood, however,
that
the individual connections of the coils 1770, 1772 to the leaves 640', 650'
may allow for
independent movement (e.g. amount and/or direction) of each of the leaves
640'a,
640'b, 650'a, and 650'b relative to one another and the stage 1620.
[00162] The
collimator 198, as illustrated in Fig. 9 may also include filters in
addition to the high speed filter 200, according to various embodiments
including the
high speed filter 200c, as illustrated in Fig. 9. Additional filters may
include filtering
elements or portions for various features such as tailoring the beam spectrum
to
optimize imaging performance when acquiring the image data. The filters may be
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provided in a multiple element or position filter assembly 2000. The filter
assembly
2000 may include a plurality of filter positions or locations 2010, including
individual
positions 2010a, 2010b, 2010c, 2010d, 2010e, 2010f, 2010g, and 2010h. The
filter
locations 2010 may be formed as passages or openings in a filter carrier or
plate 2014.
At each of the filter positions 2010, a selected filter material may be
included. The filter
material may be placed in a void or opening formed in the filter carrier 2014.
The filter
material may be opaque or transparent to various wavelengths or energies. For
example, the filter position 2010a may include a filter material such as
copper, tin,
silver, aluminum, alloys thereof, layered materials, or other appropriate
material with a
selected Z reference value that limits or selected a type or energy level of x-
rays for
passing through the exposure opening 600 of the collimator 198. Further, one
or more
of the filter positions 2010 may not include any filter material, thus
providing a void, to
form an unfiltered passage through the filter carrier 2014 for x-rays or other
emissions.
Certain filter materials or materials may be provided that do not
substantially interact
with x-rays so that the filter position acts as a void even if a material is
within the path of
the x-rays.
[00163]
The filter plate 2014 may be formed as a substantially circular plate
member having exterior perimeter teeth 2020. The teeth 2020 allow the filter
carrier
2014 to be rotated around a central axis 2022 on an axle or spindle 2024 to
position
one of the filter positions 2010 relative to the exposure opening 600. The
external teeth
2020 may be engaged by a spindle gear 2030 having external teeth that is
driven by a
motor assembly 2032. The motor assembly 2032 may be controlled by the
controller
32 through a communication system 2034. The communication system may be any
appropriate communication system, such as a wired, wireless, or other
appropriate
communication system. The motor assembly 2032 may include any appropriate type
of
motor such as a servo motor or stepper motor. The motor assembly 2032 may
drive
the external gear 2030 to rotate the filter carrier 2014 according to a
selected plan or
instructions, such as instructions that may be stored on the memory 33b.
[00164]
The filter assembly 2000 may further include a position sensor
assembly 2040 that may communicate with a controller 32 through a
communication
line 2042. The position sensor 2040 may include a spindle gear 2044 that is
engaged
on the exterior teeth 2020 of the filter carrier 2014. As the filter carrier
2014 rotates, the
spindle gear 2044 may also rotate and the sensor 2040 may determine a relative
or
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absolute position of the filter carrier 2014 based upon movement of the
spindle gear
2044.
[00165]
The position sensor 2040 may include an optical or mechanical
encoder, such as the US Digital 54T optical shaft encoder. Based upon the
position
sensor 2040, the motor 2032 may be operated to position a selected one of the
filter
elements in a selected one of the filter positions 1020a-h relative to the
exposure
opening 600. The filter carrier 2014 may spin or rotate on the axis 2022 on
the axle
2024 that is selectively fixed to the frame 660. The frame 660 that may hold
the ASA
626a may be fixed relative to the exposure opening 600. It is understood,
however,
that the axle 2024 may be fixed to any appropriate portion of the collimator
198,
including the housing 608. Therefore, the position of the filter carrier 2014
may be
rotated relative to the exposure opening 600 by operating the motor 2032.
Similarly,
the high speed filter 200c may be mounted on the frame 660.
[00166]
With continued reference to Fig. 9 and additional reference to Fig.
13, a multiple element or position filter assembly 2100 is illustrated. The
filter assembly
2100 may include a filter carrier 2110. The filter carrier 2110 may include
the plurality
of filter positions 2010a-2010h, similar to the filter positions discussed
above of the filter
assembly 2000. Again, the filter carrier 2110 may be rotated around the axis
2022 on
an axle 2130 to position one of the filter positions 2010a-h relative to the
exposure
opening 600, to position the filter position 2010 relative to the exposure
opening 600.
[00167]
The filter assembly 2100, however, may be driven by a drive
assembly similar to the drive assembly of the high speed filter 200c, as
discussed
above and illustrated in Fig. 5 and Fig. 6. The drive assembly for the filter
assembly
2100, therefore, may include the carry gear 360 (not illustrated in Fig. 13)
which holds
or carries the filter carrier 2110, as discussed above. The carrier gear 360
may be
driven by the belt 364 that is driven by the drive gear 366 on the shaft 370.
The shaft
370 may be driven by the motor assembly 374. As discussed above, the motor
assembly 374 may include a motor within a housing 376 that may be controlled
by the
controller 32 with the communication or control line 380. The motor assembly
374 may
be controlled to position a selected one of the filter positions 2010 relative
to the
opening 600 in a manner similar to that discussed above. The different
positions 2010
may be identified with various sensors, such as index sensors and the like to
determine
the position of the filter plate 2110. The filter assembly 2000, however, may
be
operated in a non-continuous motion operation, therefore absolute position
sensors
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may be used to determine which of the filter positions 2010a-h are aligned
with the
exposure opening 600.
[00168]
The plurality of filter potions 2010a-h of the filter assembly 2000
and the filter assembly 2100 generally allows one of the filter positions
2010a-h to be
positioned relative to the exposure opening 600 for a selected period of time.
Therefore, the filter plate or carrier 2014 or 2110 generally may not rotate
continuously
during an imaging procedure. Accordingly, the motor assembly and sensors may
be
selected based upon the reduced amount of motion and may include absolute
position
sensors to determine a position of the filter carrier, including the filter
positions 2010
relative to the opening 600.
[00169]
With reference to Fig. 14, a filter assembly 2200 is illustrated. The
filter assembly 2200 is illustrated positioned relative to the stage 1620 of
the ASA 626b
illustrated in Fig. 11. It is understood, however, that the filter assembly
2200 may be
positioned relative to any appropriate portion of the collimator 198. The
filter assembly
2200 may include a grid or patterned filter carrier 2210 that includes a
plurality of filter
positions or openings 2220a-2220i. The filter carrier may move in a plane and
generally in two axes, e.g. X-axis and Y-axis.
[00170]
Each of the filter positions 2220 may include a different filter
material and/or be open to not filter any transmission through the exposure
opening
1624. The filter carrier 2210 may be moved relative to the exposure opening
1624
and/or the opening 600 of the collimator 198 by movement along parallel rails.
A first
set of parallel rails includes a first rail 2230a and 2230b. The first set of
parallel rails
2230 may be fixed to the stage 1620. A number of cars, including four cars
2232a-
2232d may move along the rails 2230 generally in the direction of the double-
headed
arrow 2236.
[00171]
Mounted to the first set of cars 2232 may be a plurality of additional
cars 2240a-2240d as the first set of cars 2230 move in the direction of double-
headed
arrow 2236, they move the second set of cars 2240 in the same direction.
Movable
relative to the second set of cars 2240 may be a second set of rails including
a third rail
2250a and fourth rail 2250b. The second set of rails 2250 may generally move
in a
direction of double-headed arrow 2254. The filter carrier 2210 may be fixed to
the
second set of rails 2250 in any appropriate manner, such as with welding,
adhesives, or
fasteners.
46
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[00172]
As the second set of rails 2250 moves in the direction of double-
headed arrow 2254, the filter carrier 2210 also moves in the direction of the
double-
headed arrow 2254. Further, because the rail members 2250 are interconnected
with
the first set of cars 2232, the frame carrier 2210 also moves in the direction
of double-
headed arrow 2236 in a selected manner. Therefore, the filter carrier 2210 may
be
moved relative to the exposure opening 1624 in the stage 1620 and/or the
exposure
opening 600 in the direction of either double-headed arrow 2236 or 2254, such
as x and
y directions.
[00173]
Movement of the cars 2232 or the rails 2250, relative to the cars
2240, may be formed in any appropriate manner. For example, as discussed
above,
lead screws driven by selected motors (e.g., servo motors or stepper motors),
linear
motors, or other appropriate motor drive mechanisms may be used to move the
respective cars 2232 and/or the rails 2250. In this way the filter carrier
2210 may be
moved relative to the exposure opening 1624.
[00174]
According to various embodiments, the frame carrier 2210 may
include only a single row of filter positions, rather than a grid.
In a single row, the
frame carrier need only move in a single axis, such as only translate along
the X-axis.
In such a configuration, the frame carrier may resemble a ladder where a
filter position
is between each rung of the ladder. The ladder filter carrier may also reduce
the
number of rails and/or cars riding on rails needed to move the ladder. For
example, the
ladder may be moved on a single pair of parallel rails in the X-axis. The
ladder frame
carrier may be moved in two directions, however, along the X-axis. The
movement of
the ladder filter carrier may be powered by any selected appropriate motor,
such as
linear motors as discussed above. The linear motor may be positioned to move
the
ladder filter carrier relative to the exposure opening 600. Further, the
ladder filter
carrier may be moved based on instructions or control from the controller 32.
[00175] The foregoing description of the embodiments has been provided for
purposes of illustration and description. It is not intended to be exhaustive
or to limit the
invention. Individual elements or features of a particular embodiment are
generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and
can be used in a selected embodiment, even if not specifically shown or
described.
The same may also be varied in many ways. Such variations are not to be
regarded as
a departure from the invention, and all such modifications are intended to be
included
within the scope of the invention.
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