U.S. patent application number 10/955616 was filed with the patent office on 2006-03-30 for linear array detector system and inspection method.
This patent application is currently assigned to General Electric Company. Invention is credited to Andrew Joseph Galish, Forrest Frank Hopkins, William Robert Ross.
Application Number | 20060067471 10/955616 |
Document ID | / |
Family ID | 35883793 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060067471 |
Kind Code |
A1 |
Hopkins; Forrest Frank ; et
al. |
March 30, 2006 |
Linear array detector system and inspection method
Abstract
A linear array detector (LAD) for scanning an object is
provided. The detector includes a scintillator layer configured for
generating a number of optical signals representative of a fraction
of an incident X-ray beam passing through the object. The plane of
the scintillator is parallel to the X-ray beam. The LAD further
includes a two dimensional array of photo-conversion elements
configured to receive several X-rays of the X-ray beams and
configured to generate corresponding electrical signals. An
arrangement of the photo-conversion elements is independent of the
X-ray paths.
Inventors: |
Hopkins; Forrest Frank;
(Scotia, NY) ; Galish; Andrew Joseph; (West
Chester, OH) ; Ross; William Robert; (Scotia,
NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY;GLOBAL RESEARCH
PATENT DOCKET RM. BLDG. K1-4A59
NISKAYUNA
NY
12309
US
|
Assignee: |
General Electric Company
|
Family ID: |
35883793 |
Appl. No.: |
10/955616 |
Filed: |
September 30, 2004 |
Current U.S.
Class: |
378/98.8 |
Current CPC
Class: |
G01T 1/2018
20130101 |
Class at
Publication: |
378/098.8 |
International
Class: |
H05G 1/64 20060101
H05G001/64 |
Claims
1. A linear array detector (LAD) for scanning an object, the
detector comprising: a scintillator layer configured for generating
a plurality of optical signals representative of a fraction of an
incident X-ray beam passing through the object, wherein the plane
of the scintillator is parallel to the X-ray beam; and a two
dimensional array of photo-conversion elements configured to
receive a plurality of X-rays of the X-ray beams and configured to
generate a corresponding plurality of electrical signals; wherein
an arrangement of the photo-conversion elements is independent of
the plurality of X-ray paths.
2. The LAD of claim 1, further comprising a light delivery means
configured for transporting the optical signals to the
two-dimensional array.
3. The LAD of claim 2, wherein the light delivery means comprises a
fiber optic plate.
4. The LAD of claim 2, wherein the light delivery means comprises a
fiber optic taper.
5. The LAD of claim 2, wherein the light delivery means comprises
an optical lens.
6. The LAD of claim 1, wherein the photo-conversion elements are
arranged in an orthogonal geometry with a plurality of rows and a
plurality of columns.
7. The LAD of claim 1, wherein the incident X-ray beam has an
energy spectrum with an end point energy in a range of about 30 keV
to about 16 MeV.
8. The LAD of claim 1, wherein the two-dimensional array comprises
at least one of an amorphous silicon flat panel or a charge coupled
device array.
9. The LAD of claim 1, wherein a thickness of the scintillator
layer is in a range of about 50 microns to about 5 centimeters.
10. The LAD of claim 1, wherein the LAD is configured to
accommodate a photon count rate of up to about 100 GHz
11. The LAD of claim 1, wherein the LAD is configured to scan with
a plurality of geometries.
12. The LAD of claim 1, wherein the LAD is adapted for use in an
energy-integrating digital radiography system.
13. The LAD of claim 1, wherein the LAD is adapted for use in an
energy-integrating computed tomography system.
14. The LAD of claim 1, wherein the photo-conversion elements
comprise photodiodes.
15. A system for scanning an object having an arbitrary geometry,
the system comprising: at least one detector configured for
generating electrical signals representative of an incident X-ray
beam passing through the object, wherein the detector comprises a
scintillator and a two dimensional array of photo-conversion
elements; and a processor coupled to the detector and configured
to: determine an X-ray path geometry from the two dimensional
array, wherein the X-ray path geometry comprises at least one X-ray
path, and wherein the X-ray path passes through at least one of the
photo-conversion elements, determine an energy deposition profile
for at least one segment of the X-ray paths, and generate an image
of the object based on the energy deposition profile and the X-ray
paths.
16. The system of claim 15, wherein the processor is configured to
determine the X-ray path geometry based on imaging at least one
fiducial.
17. The system of claim 16, wherein the processor is further
configured to bin the energy deposition profile into at least two
segments of deposition.
18. The system of claim 17, wherein the processor is further
configured to determine a plurality of optimal segments of energy
deposition for an application in a post-data acquisition
fashion.
19. The system of claim 18, wherein the processor is configured to
perform a search to determine a dependence of at least one of an
image quality and a material-specific detectability on the X-ray
path geometry.
20. The system of claim 19, wherein the application corresponds to
an object size, an object type, and a source energy.
21. The system of claim 15, wherein the system is used for
non-destructive evaluation.
22. The system of claim 15, wherein the system is an explosive
detection system.
23. The system of claim 15, wherein the system is a computed
tomography system.
24. The system of claim 15, wherein the system is a digital
radiography system.
25. An inspection method for inspecting an object, the method
comprising; impinging an incident X-ray beam on the object;
receiving the X-ray beam passing through the object with a
detector, the detector comprises a scintillator and a two
dimensional array of photo-conversion elements, wherein the
scintillator is aligned parallel to the X-ray beam; determining an
X-ray path geometry from the two dimensional array, wherein the
X-ray path geometry comprises at least one X-ray path; determining
an energy deposition profile for at least one segment of each of
the at least one X-ray path; and generating an image of the object
using the at least one X-ray path and the energy deposition
profile.
26. The inspection method of claim 22, wherein determining the
X-ray path geometry includes imaging at least one fiducial.
27. The inspection method of claim 22, further comprising binning
the energy deposition profile into at least two segments of
deposition, wherein each of the segments of deposition corresponds
to a respective x-ray energy level.
28. The inspection method of claim 24, wherein the segments
comprise contiguous segments of deposition
29. The inspection method of claim 24, wherein the segments
comprise non-contiguous segments of deposition.
30. The inspection method of claim 24, wherein the energy
deposition profile is binned into a first and a second segment of
deposition, the first segment corresponding to low-energy X-rays
and the second segment corresponding to high-energy X-rays.
31. The inspection method of claim 27, further comprising
processing the image using the energy deposition profile
corresponding to the high-energy X-rays and to the low-energy
X-rays to provide a material-specific detection capability.
32. The inspection method of claim 22, wherein the method is
adapted for use in non-destructive evaluation (NDE) of
materials.
33. The inspection method of claim 29, wherein the NDE of materials
include evaluation of turbine airfoils and turbine blades.
34. The inspection method of claim 29, wherein the NDE of materials
include the determination of corrosion and inclusions.
35. The inspection method of claim 29, wherein the NDE of materials
include the detection of debris inside a pipe.
36. The inspection method of claim 32, wherein the pipe is used for
transporting water, gas, or oil.
37. The inspection method of claim 22, wherein the method is
adapted for use in baggage inspection systems.
38. The inspection method of claim 22, wherein the method is
adapted for use in cargo inspection systems.
39. The inspection method of claim 22, wherein the method is
adapted for use in digital radiography systems.
40. The inspection method of claim 22, wherein the method is
adapted for use in computed tomography systems.
41. The inspection method of claim 22, wherein the method is
adapted for use in explosives detection systems.
Description
BACKGROUND
[0001] The invention relates generally to imaging systems and more
specifically to a method and system for acquiring images.
[0002] Many industrial inspection systems require very high
detection efficiency, excellent signal-to-noise performance and
coverage. In addition, it is desired that the overall cost of the
industrial system is reasonable.
[0003] Linear detection arrays may be used for various low energy
and high-energy x-ray inspection applications. Such detector arrays
receive X-rays emitted by a source and passing through an object
that is required to be scanned. Typically such arrays have limited
flexibility as the detectors generally involve fixed geometry
configurations.
[0004] Typically, such detectors include a scintillator layer and a
photoconversion device. The photoconversion device has many
photosensor elements. The photosensor elements are arranged based
on one or more pre-determined paths that the X-rays follow. FIG. 1
is a block diagram of a conventional X-ray inspection system. X-ray
source 10 generates an X-ray beam with X-ray paths 7, 8 and 9
respectively. The photosensor elements 6 are aligned with respect
to the respective X-ray paths. Thus, for a particular
source-to-detector distance (SDD), photosensor elements are focally
aligned with the respective X-ray path.
[0005] Current X-ray inspection methods typically produce spectrum
dependent information by performing two or more different scans,
where each scan is achieved with a particular voltage setting of an
industrial x-ray tube, typically in conjunction with an
energy-integrating detector. Another method is to use a detector
with two or more separate distinct layers in succession of the same
or different, attenuating materials.
[0006] In a multi-layer approach, lower energy X-rays tend to be
attenuated in the first layer, and higher energy X rays tend to
penetrate through to and be attenuated by the second layer. Another
method is to use a photon counting detector which produces an
amplitude spectrum of absorbed energy and which can be binned in
energy to provide energy separation. All of these methods,
generally referred to as energy discrimination, allow the
extraction of information on material-specific constituents, rather
than information on electron density provided by energy-integrating
detectors.
[0007] It may also be required that inspection systems be
configured to identify and/or quantify specific materials in an
object, which is particularly useful in several nondestructive
testing and security inspection applications. However, a
conventional inspection image data set, produced with a single
source spectrum and an energy-integrating detector, permits only
the extraction of information on material density. Usually, little
information on the amounts of specific materials can be extracted
from these conventional image data sets.
[0008] Therefore, there is a need to design detectors that are
capable of scanning various arbitrary geometries for different
source to detector distances, while maintaining high x-ray
detection efficiency, spatial resolution and material-specific
detection capability.
BRIEF DESCRIPTION
[0009] Briefly, according to one embodiment of a linear array
detector (LAD) for scanning an object, the LAD includes a
scintillator layer configured for generating optical signals
representative of a fraction of an incident X-ray beam passing
through the object. The plane of the scintillator is parallel to
the X-ray beam. The LAD further includes a two dimensional array of
photo-conversion elements for receiving a number of X-rays and
configured to generate a corresponding number of electrical
signals. The arrangement of the photo-conversion elements is
independent of the X-ray paths.
[0010] In another embodiment, a system for scanning an object
having an arbitrary geometry is provided. The system includes at
least one detector configured for generating electrical signals
representative of an incident X-ray beam passing through the
object. The detector includes a scintillator and a two dimensional
array of photo-conversion elements. The system further includes a
processor coupled to the detector. The processor is configured to
determine an X-ray path geometry from the two dimensional array.
The X-ray path geometry includes at least one X-ray path, which
passes through at least one of the photo-conversion elements. The
processor is further configured to determine an energy deposition
profile for at least one segment of the X-ray paths and generate an
image of the object based on the energy deposition profile and the
X-ray paths.
[0011] In another embodiment, a method for inspecting an object is
provided. The inspection method includes impinging an incident
X-ray beam on the object and receiving the X-ray beam passing
through the object with a detector. The detector includes a
scintillator and a two dimensional array of photo-conversion
elements and the scintillator is aligned parallel to the x-rays.
The inspection method further includes determining an X-ray path
geometry from the two dimensional array, wherein the X-ray path
geometry includes at least one X-ray path. The inspection method
further includes determining an energy deposition profile for at
least one segment of each of the X-ray paths and generating an
image of the object using the X-ray paths and the energy deposition
profile.
DRAWINGS
[0012] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0013] FIG. 1 is a block diagram of an exemplary, conventional
X-ray inspection system;
[0014] FIG. 2 is a block diagram of a digital radiography system
for generating images implemented according to one aspect of the
invention;
[0015] FIG. 3 is side view of one embodiment of a linear array
detector;
[0016] FIG. 4 is side view of another embodiment of a linear array
detector;
[0017] FIG. 5 is a diagrammatic view of one embodiment of a two
dimensional array of photosensor elements;
[0018] FIG. 6 is a flow chart illustrating one method by which an
object can be imaged using a linear array detector;
[0019] FIG. 7 is one embodiment of a computed tomography system
configured for inspecting pipes;
[0020] FIG. 8 is a block diagram illustrating an embodiment of a
baggage or cargo scanning system; and
[0021] FIG. 9 is a block diagram illustrating an embodiment of a
turbine blade inspection system.
DETAILED DESCRIPTION
[0022] FIG. 2 is a block diagram of an embodiment of a system 10,
which is an X-ray system designed both to acquire original image
data and to process the image data for display and analysis in
accordance with the present technique. Other imaging systems such
as computed tomography system and digital radiography systems,
which acquire image three dimensional data for a volume, also
benefit from the present techniques. The following discussion of
X-ray system 10 is merely an example of one such implementation and
is not intended to be limiting in terms of modality.
[0023] As used herein, "adapted to", "configured" and the like
refer to devices in a system to allow the elements of the system to
cooperate to provide a described effect; these terms also refer to
operation capabilities of electrical or optical elements such as
analog or digital computers or application specific devices (such
as an application specific integrated circuit (ASIC)), amplifiers
or the like that are programmed to provide an output in response to
given input signals, and to mechanical devices for optically or
electrically coupling components together.
[0024] As indicated in FIG. 2, X-ray system 10 includes an X-ray
source 13 configured to emit X-ray radiation through object 14.
Object 14 may include turbine blades, baggage, pipes and also the
human body, a portion of the human body and animals. X-ray source
13 may be a conventional x-ray tube producing x-rays having both
high energy and low energy x-rays. Typically, the end-point energy
of the X-rays varies from about 30 keV to about 16 MeV. The X-rays
continue through object 14 and, after being attenuated by the
object, impinge upon linear array detector 16. Linear array
detector (LAD) 16 is a scintillation based LAD is described in
further detail with reference to FIG. 5. The linear array detector,
with individual photoconversion elements operated in the energy
integration mode, is configured to accommodate photon count rates
up to the order of gigahertz levels.
[0025] Processor 20 receives signals from the linear array detector
16 and is configured to generate an image corresponding to the
object being scanned. The processor is configured to determine an
X-ray path geometry and determine an energy deposition profile for
at least one segment of each of the X-ray paths. The processor is
further configured to generate an image of the object based on the
energy deposition profile and the X-ray paths. The optimum segments
of energy deposition for a particular application, e.g., for a
specific object size and type and source energy, can be determined
in a post-data acquisition fashion by a search on the dependence of
image quality and material-specific detectability on X-ray path
geometry. The manner in which the image is generated based on the
X-ray path geometry and the energy deposition profile is described
in further detail with reference to FIG. 4
[0026] For the exemplary embodiment of FIG. 2, computer 24
communicates with processor 20 to enable an operator, using
operator console 26, to view the generated image. The operator may
view the image on display unit 28. The generated image may also be
stored in storage device 30 which may include hard drives, floppy
discs, compact discs, etc. The operator may also use computer 24 to
provide commands and instructions to source controller 22. Source
controller 22 provides power and timing signals to x-ray source
13.
[0027] The X-ray system can be used for various non-destructive
applications in digital radiography systems or computed tomography
systems, such as material identification, explosive detection,
baggage scanning and non-destructive inspection methods. For
example, the system can be used to determine corrosion in metallic
structures or ceramic cores in turbine blades. Additionally, the
system may be used to detect debris in pipes carrying, for example,
water, oil, or gas.
[0028] As shown for example in FIG. 2, linear array detector (LAD)
16 is configured to receive X-rays of varying intensities. FIG. 3
is a side view illustrating one embodiment of linear array detector
16. Each component is described in further detail below.
[0029] LAD 16 includes a scintillator layer 32 configured for
generating a number of optical signals representative of a fraction
of an incident X-ray beam 17 passing through the object 14. For
high resolution imaging applications, the thickness of the area
scintillator ranges between about 50 microns to about 1000 microns.
For medium resolution imaging applications, the thickness of the
area scintillator ranges between about 1 mm to about 5 cm. Examples
of scintillators include cesium iodide (fiberized and solid),
gadolium oxysulfide, and cadmium tungstate. The volume of the
scintillator receives the incident X-ray beam.
[0030] The LAD further includes a two-dimensional array 34 coupled
to the scintillator layer. The two dimensional array is configured
for converting optical signals to corresponding electrical signals
that may include pulse signals. Each pulse signals represents a
fraction of the energy deposited in the scintillator.
[0031] The two dimensional array includes a number of
photoconversion elements as will be described in further detail in
FIG. 5. In one embodiment, the two-dimensional array comprises an
amorphous silicon flat panel. As can be seen from FIG. 3, a plane
of the scintillator layer is parallel to X-ray beam 17.
[0032] FIG. 4 is a side view of an alternate embodiment of the LAD
16, which further includes a light deliver means 36 disposed
between the scintillator layer 32 and the two-dimensional array 34.
The light delivery means is configured for efficiently transporting
the optical signals to the two-dimensional array of
photo-conversion elements. One exemplary light delivery means is a
fiber optic layer, for example a fiber optic plate. Other exemplary
means include tapered light pipes and optical systems which
typically involve focusing and directing of the light with lenses
and reflection mirrors to the area of the photo-conversion device.
As can be seen from FIG. 4, a plane of the scintillator layer is
parallel to X-ray beam 17.
[0033] FIG. 5 is a diagrammatic top view of one embodiment of a
two-dimensional array 34. Although the scintillator layer (not
shown in FIG. 5) converts the X-ray beam 17 passing through the
object into a number of optical signals, the path taken by a
particular X-ray is referred to herein as an X-ray path. The light
generated by X-ray attenuation along a particular X-ray path and
transmitted to the two dimensional array leads to a signal
associated with the particular X-ray path. FIG. 5 illustrates three
such X-ray paths, which are represented by reference numerals 38,
40 and 42 respectively. The two dimensional arrays converts the
optical signals on X-ray paths 38, 40 and 42 to electrical signals
represented by 44, 46 and 48 respectively.
[0034] The two dimensional array 34 includes a number of
photo-conversion elements configured for converting the optical
signals to corresponding electrical signals. In one embodiment, the
photo-conversion elements are photodiodes. In the illustrated
figure, the photo-sensors that align with one of the X-ray paths
are represented by reference numeral 50. The photo-sensors that are
not aligned with one of the X-ray paths are represented by
reference numerals 52, 56 and 58.
[0035] As can be seen from FIG. 5, the arrangement of the
photo-conversion elements is independent of the X-ray path and can
be a regular arrangement or an irregular arrangement. Thus, while
scanning another object, the X-ray paths may be aligned with
photoconversion elements 52, 56 and 58. Thus, the linear array
detector is capable of scanning a number of geometries because the
arrangement of the photo-conversion elements is not dependent on
the X-ray path.
[0036] In the illustrated embodiment, the photo-conversion elements
are arranged in the form of an orthogonal grid pattern. The angle
between two photo-conversion elements such as 50 and 52 is ninety
degrees. It may be noted that the angles between the two
photo-conversion elements may be different for different
embodiments of the LAD. The LAD as described above may be used in
various systems such as energy-integrating digital radiography
system and energy-integrating computed tomography system.
[0037] FIG. 6 is a flow chart illustrating one inspection method by
which an object can be imaged using a linear array detector. In
step 62, an X-ray beam is impinged on an object using an X-ray
source. In step 64, the X-ray beam that passes through the object
is received by a linear array detector (LAD). In one embodiment,
the LAD detector includes a scintillator layer and a two
dimensional array of photo-conversion elements.
[0038] In step 66, an X-ray path geometry from the two dimensional
array is determined by a processor. The X-ray path geometry
includes at least one X-ray path. The X-ray path passes through at
least one photo-conversion element of the two dimensional array.
The X-ray path has a corresponding energy deposition profile with a
granularity established by the impinging X-ray beam on the
scintillator layer, the composition and depth of a scintillator
material used in scintillator layer and a pixel pitch of the
recorded image.
[0039] In one embodiment, the X-ray path geometry is determined by
imaging at least one fiducial. In one embodiment, the fiducials are
imaged by placing tungsten pins in a known configuration within
imaging field-of-view 15. Imaging of the fiducials facilitates the
mapping of the X-ray path geometry for a particular
source-to-detector distance (SDD) to the energy deposition recorded
by a regular or irregular grid of photo-conversion elements.
[0040] In step 68, an energy deposition profile is determined for
at least one segment of each of the X-ray paths. In a further
embodiment, the energy deposition profile is binned into at least
two segments of deposition, each segment of deposition
corresponding to energy deposition associated primarily with
specific X-ray energies or with a particular range of energies
(e.g., relatively low or high energies in a polychromatic x-ray
spectrum).
[0041] In a more specific embodiment, the energy deposition profile
is binned into a first segment and a second segment of deposition.
The first segment corresponds to low-energy X-rays and the second
segment corresponds to high-energy X-rays. The segments may be
contiguous segments of deposition or non-contiguous segments of
deposition.
[0042] In step 60, an image of the object is generated using the
X-ray paths and the energy deposition profile. In one embodiment,
the image of different constituents of object 14 is further
processed by using the energy deposition profile corresponding to
the high-energy X-rays and to the low-energy X-rays to increase
material-specific detection capability.
[0043] As described earlier with reference to FIG. 1, the method
may be used in digital radiography systems and computed tomography
systems. Further, the method is adapted for use in non-destructive
evaluation (NDE) of materials. One such example is the NDE of
turbine airfoils and turbine blades. FIG. 7 is a block diagram
illustrating one method by which pipes may be inspected according
to one aspect of the invention.
[0044] Non-destruction evaluation of materials may also be used for
the inspection of pipes for cracks, corrosion, or debris in the
interior. FIG. 7 is a block diagram of an exemplary C-arm computed
tomography (CT) system 72 used for detecting cracks in pipe 74. The
CT system is mounted on trolley 78 and X-rays are emitted from
source 76 through the pipe so that cracks may be detected over a
length of the pipe. The cracks may be detected by using the method
described with reference to FIG. 6. In another embodiment, the CT
system illustrated in FIG. 7 may also be used to detect debris
inside the pipe. In a more specific embodiment, the CT system may
be used to detected debris inside a pipe transporting water, gas,
or oil.
[0045] Non-destruction evaluation of materials may also be used for
the inspection of baggage. FIG. 8 is a block diagram of an
exemplary baggage scanning system 80 used for detecting explosives
or other objects in baggage 92. The baggage is mounted on trolley
84, and X-rays are emitted from source 82 through the baggage. The
detector 16, implemented as described with reference to FIG. 2 and
FIG. 3, receives the X-ray beam. Processor 86 employs the method
described with reference to FIG. 6 for detecting explosives and
other objects in the baggage. The contents of the baggage may be
displayed to a user using the baggage scanning system via display
88. Similar approaches could be used for cargo inspection for
explosives and contraband detection.
[0046] NDE may also be used for the evaluation of turbine blades.
FIG. 9 is a block diagram of an exemplary turbine inspection system
90 used for inspecting defects in turbine blades. An example of a
defect is a presence of a residual core in the turbine blade. The
turbine blade is mounted on support 96, and X-rays are emitted from
source 92 through the turbine blade. The detector 16, implemented
as described with reference to FIG. 2 and FIG. 3, receives the
X-ray beam. Processor 98 employs the method described with
reference to FIG. 6 for detecting defects in the turbine blade.
[0047] The above-described invention has several advantages
including flexibility in the initial scanning geometry as the
linear array detector (LAD) detector can be configured to scan at
any source-to-detector distance that is optimum for scanning of
objects with a particular detector field of view. Processing of the
energy deposition profile in a post data acquisition process allows
the utilization of any distance within a large range between about
1 cm to about 1200 cm.
[0048] Additionally, the establishment of the X-ray path is
accurate and does not require precise physical alignment of the
detector with respect to the centerline of the object, as the
geometrical calibration afforded by the imaging of fiducials
establishes the geometry of the x-ray paths irrespective of the
particular orientation of the detector with respect to the ray path
geometry.
[0049] When the linear array is used with appropriate thickness,
the use of the solid sheet or layer of scintillator with limited
thickness or a fiberized scintillator provides for spatial
resolution. Also, the linear array detector provides high detection
efficiency for a large range of source energies due to the extended
depth of the area scintillator.
[0050] The linear array detector is also of high efficiency as an
energy discrimination detector because the spectrum impinging on
the detector during a single scan can be separated into regions
associated with attenuation of low energy X-rays and high energy X
rays, thus obviating the need for a second scan with a different
X-ray spectrum.
[0051] The linear array detector is also capable of separating
attenuation of events as a function of depth along a given X-ray
path and the corresponding separation of low energy X-ray
attenuation and high energy X-ray attenuation. This provides for
dynamic, post processing optimization of energy discrimination
sensitivity using software, achieved as a data processing step.
[0052] Also, the linear array detector is configured to accommodate
relatively high x-ray count rates (greater than 1 GHz) resulting in
high signal quality. Also, the linear array detector can be easily
incorporated in various imaging systems.
[0053] Although only certain features of the invention have been
illustrated and described herein, many modifications and changes
will occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention.
* * * * *