U.S. patent application number 14/837205 was filed with the patent office on 2016-03-24 for low-angle self-swinging, large-scale multi-slice spiral computed tomography apparatus and inspection method.
The applicant listed for this patent is Nuctech Company Limited, Tsinghua University. Invention is credited to Zhiqiang CHEN, Jianping GU, Kejun KANG, Liang LI, Yuanjing LI, Yaohong LIU, Yuxiang XING, Li ZHANG, Ziran ZHAO.
Application Number | 20160084775 14/837205 |
Document ID | / |
Family ID | 52083831 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160084775 |
Kind Code |
A1 |
KANG; Kejun ; et
al. |
March 24, 2016 |
LOW-ANGLE SELF-SWINGING, LARGE-SCALE MULTI-SLICE SPIRAL COMPUTED
TOMOGRAPHY APPARATUS AND INSPECTION METHOD
Abstract
The present disclosure provides a low-angle self-swinging type
computed tomography (CT) apparatus, which is provided with an X-ray
accelerator and a plurality of rows of detectors and is configured
to include a slip ring, such that the slip ring with the
accelerator and the detectors thereon is capable of performing a
single-pendulum reciprocating movement while an objected to be
inspected passes through the slip ring, a three dimension CT image
of the object is displayed, thereby achieving accurate inspection
for large-scale objects, such as van containers.
Inventors: |
KANG; Kejun; (Beijing,
CN) ; CHEN; Zhiqiang; (Beijing, CN) ; LI;
Yuanjing; (Beijing, CN) ; ZHANG; Li; (Beijing,
CN) ; ZHAO; Ziran; (Beijing, CN) ; LIU;
Yaohong; (Beijing, CN) ; GU; Jianping;
(Beijing, CN) ; LI; Liang; (Beijing, CN) ;
XING; Yuxiang; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tsinghua University
Nuctech Company Limited |
Beijing
Beijing |
|
CN
CN |
|
|
Family ID: |
52083831 |
Appl. No.: |
14/837205 |
Filed: |
August 27, 2015 |
Current U.S.
Class: |
378/15 |
Current CPC
Class: |
G01V 5/005 20130101;
G01N 23/046 20130101 |
International
Class: |
G01N 23/04 20060101
G01N023/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 27, 2014 |
CN |
201410427466.X |
Claims
1. A low-angle self-swinging type computed tomography apparatus,
comprising: an X-ray generator configured to emit X-rays towards an
object to be inspected; a data acquisition sub-system configured to
collect signals of the X-rays passing through the object for
inspection; a swinging support device, on which the X-ray generator
and the data acquisition sub-system are arranged and spaced from
each other, wherein the swinging support device is configured to be
able to reciprocate in a swinging way with the X-ray generator and
the data acquisition sub-system carried thereon while the object to
be inspected is located in or passing through an inspecting region
between the X-ray generator and the data acquisition
sub-system.
2. The computed tomography apparatus according to claim 1, wherein
the reciprocating movement of the pendulous support device is a
single-pendulum reciprocating movement achieved under offset of the
center of gravity of the swinging support device.
3. The computed tomography apparatus according to claim 1, wherein
the swing support device is configured to move at a constant
velocity during most of its travel except for two end-regions of
the travel.
4. The computed tomography apparatus according to claim 1, wherein
the swinging support device is a slip ring, and the X-ray generator
and the data acquisition sub-system are arrange on a circumference
of the slip ring and located opposite to each other with respect to
a center of the slip ring.
5. The computed tomography apparatus according to claim 1, wherein
the swinging support device has a maximum swinging amplitude of no
more than 180 degrees.
6. The computed tomography apparatus according to claim 1, wherein
the X-ray generator includes a large-power X-ray accelerator.
7. The computed tomography apparatus according to claim 1, wherein
the X-ray generator is configured to provide an X-ray beam in a
cone or sector shape.
8. The computed tomography apparatus according to claim 1, wherein
the data acquisition sub-system comprises a plurality of rows of
detectors.
9. The computed tomography apparatus according to claim 1, further
comprising a carrier configured to carry the object to be inspected
to pass through the inspecting region defined by the X-ray
generator and the data acquisition sub-system.
10. The computed tomography apparatus according to claim 9, wherein
the carrier is configured to be linearly movable in two directions,
including an up-down direction and a fore-and-aft direction.
11. The computed tomography apparatus according to claim 1, further
comprising a control subsystem configured to control the movement
of the swinging support device and operations of the X-ray
generator and the data acquisition sub-system.
12. The computed tomography apparatus according to claim 1, further
comprising a data processing sub-system configured to process a
projection data collected by the data acquisition sub-system to
reconstruct a three dimension image of the object.
13. An inspection method using the computed tomography apparatus
according to claim 1, comprising: emitting X-rays by using the
X-ray generator and collecting signals of the X-rays by the data
acquisition sub-system for inspection, while operating the swinging
support device such that the X-ray generator and the data
acquisition sub-system reciprocate in a swinging way together with
the swinging support device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Chinese patent
application No. 201410427466.X, filed on Aug. 27, 2014 with State
Intellectual Property Office of China, and the disclosures of which
are incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to the field of computed
tomography (CT) inspection for air containers, and particularly, to
a low-angle self-swinging type, large scale multi-slice spiral
computed tomography (CT) inspection apparatus and an inspection
method.
[0004] 2. Description of the Related Art
[0005] Conventional CT technologies have been gradually replaced by
the spiral computed tomography (CT) technology due to its enormous
advantages. Compared to conventional CT technologies, the spiral
computed tomography (CT) technology is advantageous in that it can
continuously collect projection data and thus obtain a
three-dimensional image of an object through a specialized
reconstruction algorithm based on the collected data, thereby
greatly reducing CT scanning period time, improving resolution of
the reconstructed image in Z-axis, and reducing movement
artifact.
[0006] The main differences between the multi-slice spiral CT
technology and the single-slice spiral CT technology are in that
the multi-slice spiral CT technology has multiple rows of detectors
and thus can collect projection data of multiple layers of cone
beams simultaneously, while the single-slice spiral CT technology
has a single row of detectors and thus can only obtain projection
data of a single layer of sector-shaped beam at a time. Thus,
compared to the single-slice spiral CT technology, the multi-slice
spiral CT technology has greatly enhanced performance, including
largely increased covering scope of X-ray beams, effectively
improved utilization of X-rays, reduced scanning time and ability
to obtain three-dimension reconstruction image with higher quality.
The current multi-slice spiral CT technologies have a scanning
speed of more than three cycles per second and have been used in
wide applications. The multi-slice spiral CT technology has been
also used in combination with new technologies such as
computer-aided surgery, virtual endoscope technology and adjuvant
radio therapy, and the like.
[0007] However, the conventional multi-slice spiral CT system has
many shortages yet. The conventional multi-slice spiral CT system
occupies a large space and has a complex structure, and its X-ray
source lacks strong penetration ability. Further, the conventional
multi-slice spiral CT system uses a slip ring that is configured to
continuously rotate at high velocity, and further, to transfer
power from supply source to an X-ray machine and a plurality of
rows of detectors. In particular, when a plurality of rows of
detectors are used, a large amount of projection data produced
during scanning need to be wirelessly transmitted to a computer
which is located away from the slip ring. In this instance, the
slip ring and the communication parts are largely complicated in
structure and cost is largely increased. If an accelerator and a
large-scale detector that need high power supply are used, the
system is hard to work.
SUMMARY OF THE INVENTION
[0008] It is thus an object of the present disclosure to overcome
or address one or more of problems existing in prior arts, and to
provide a low-angle self-swinging type computed tomography
apparatus, comprising.
[0009] an X-ray generator configured to emit X-rays toward an
object to be inspected;
[0010] a data acquisition sub-system configured to collect signals
of the X-rays passing through the object for inspection;
[0011] a swinging support device, on which the X-ray generator and
the data acquisition sub-system are arranged and spaced from each
other, wherein the swinging support device is configured to be able
to reciprocate in a swing way with the X-ray generator and the data
acquisition sub-system carried thereon while the object to be
inspected is located in or passing through an inspecting region
between the X-ray generator and the data acquisition
sub-system.
[0012] According to an aspect of the present invention, there is
provided an inspection method using the above computed tomography
apparatus, comprising:
[0013] emitting X-rays by using the X-ray generator and collecting
signals of the X-rays by the data acquisition sub-system for
inspection, while operating the swinging support device such that
the X-ray generator and the data acquisition sub-system reciprocate
in a swinging way together with the swinging support device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic view of scanning operations of a
low-angle self-swinging type, large-scale multi-slice spiral CT
apparatus according to an embodiment of the present invention;
[0015] FIG. 2 is a partial sectional view of a slip ring of a
low-angle self-swinging type, large-scale multi-slice spiral CT
apparatus according to an embodiment of the present invention;
[0016] FIG. 3 is a schematic view of a scanning path of an X-ray
source of a low-angle self-swinging type, large-scale multi-slice
spiral CT apparatus according to an embodiment of the present
invention, in which the scanning path of the X-ray source is a
continuous non-smooth spiral folding line composed of sectionalized
spiral line segments; and
[0017] FIG. 4 is a schematic top view of a scanning path of an
X-ray source of a low-angle self-swinging type, large-scale
multi-slice spiral CT apparatus according to an embodiment of the
present invention in the state that the X-ray source starts to scan
from a point directly over Z-axis, wherein the scanning path of the
X-ray source is a continuous non-smooth spiral folding line
composed of sectionalized sine line-like segments.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0018] Reference to embodiments of the present invention is
provided in detail with reference to the accompanying drawings, in
which the same reference numbers represent same elements. The
embodiments of the present invention will be described with
reference to the accompanying drawings. FIGS. 1 and 2 schematically
illustrate an apparatus according to an embodiment of the present
invention.
[0019] An embodiment of the present invention provides a low-angle
self-swinging type, large-scale multi-slice spiral computed
tomography (CT) apparatus, which has an X-ray source, e.g., an
X-ray accelerator, and a plurality of rows of detectors, and which
collects full projection data required for reconstructing a CT
image of an object to be inspected by scanning the object through a
reciprocating rotation movement within 180 degrees, and provides a
three-dimension tomogram of the scanned object using corresponding
CT reconstructing and data processing technologies.
[0020] According to an embodiment of the present invention as shown
in FIG. 1, there is provided a low-angle self-swinging type,
large-scale multi-slice spiral CT apparatus. The CT apparatus
includes an X-ray generator 1 configured to emit X-ray towards an
object 6 to be inspected, and a data acquisition sub-system 3
configured to collect X-ray signals passing through the object 6 to
be inspected. The CT apparatus further includes a swinging support
device, on which the X-ray generator 1 and the data acquisition
sub-system 3 are mounted and spaced from each other, wherein the
swinging support device is configured to be able to reciprocate in
a swinging way with the X-ray generator 1 and the data acquisition
sub-system 3 carried thereon.
[0021] In an embodiment, the X-ray generator 1 includes an X-ray
accelerator source 1 and corresponding accessory equipments. Since
a van container is large in volume, it is hard to inspect such a
van container by using an X-ray generator in prior arts. In the
embodiment of the present invention, the X-ray accelerator 1 may
transmit high-power and larger energy X-rays 2 so as to scan and
inspect a van container 6. The X-ray accelerator 1 is configured to
accelerate electrons to impinge a target so as to generate X-rays
2, thereby providing a high-power cone or sector-shaped X-ray beam
2.
[0022] According to an embodiment, the X-ray generator 1 may be
arranged on the swinging support device 4 and perform a
reciprocating movement, such as simple-pendulum type swinging
movement, together with the support device 4. A swinging amplitude
of the support device 4 may not exceed 180 degrees. The swinging
amplitude of the support device 4 may be any angle within 180
degrees. FIG. 2 illustrates a schematic view of the apparatus, in
which a slip ring performs a reciprocating movement at a swinging
amplitude of 180 degrees.
[0023] According to an embodiment, the swinging support device 4
may be a slip ring 4, wherein the X-ray generator 1 and the data
acquisition sub-system 3 are respectively arranged on circumference
of the slip ring, opposite to each other about a center of the slip
ring. The swinging amplitude of the swinging support device 4 may
not exceed 180 degrees.
[0024] Preferably, the swinging amplitude of the swinging support
device 4 is equal to or less than 180 degrees. In prior arts, a
support device is often arranged to rotate continuously for 360
degrees in order to fully scan an object. However, the slip ring 4
in the embodiment of the present invention is advantageously
configured to rotate or swing within 180 degrees or less, i.e., at
a reduced swinging amplitude/angle. The reduced pendular amplitude
or angle leads to a simplified structure of the apparatus, which is
particularly favor of an apparatus used for inspecting a van
container. It is known that an X-ray accelerator has a very large
volume and huge weight and thus is usually used in prior art in
manner of fixation, because it is difficult to support and drive
such a large X-ray accelerator to perform any movement. In order to
support and drive the large X-ray accelerator, a large frame and a
high-power driving device are needed, which in turn result in an
inspecting apparatus with a complex structure. Meanwhile, the
associated equipments used for such an inspecting apparatus will be
configured with high standards and thus would be hard to be
implemented. The slip ring provided to move at a small angle
according to embodiments of the present invention may lead to
reduced power consumption and thus simplified corresponding driving
system. Further, when the slip ring 1 supporting the X-ray
accelerator 1 moves, a change in kinetic energy stood by the slip
ring is significantly reduced, which thus reduces requirements of a
support structure, enhances security of the support structure, and
is economically advantageous. In addition, a reduced swinging range
or amplitude of reciprocating movement of the slip ring 4 results
in less irradiation dose received by the object to be inspected,
which is particularly in favor of usage of the X-ray accelerator
1.
[0025] As the slip ring performs a reciprocating rotation movement
within 180 degrees around the center, an intertwisting problem of
connection lines for communication and power due to continuous
rotation is avoided. In embodiments of the present invention, a
larger amount of projection data collected by the rows of detectors
during scanning may be communicated to a back-end data processor
through optical cables or wires. Compared with wireless
communication, communication through cables leads to higher
transmission rate, higher signal-to-noise ratio and stronger
electromagnetic interference resistance. It is also particularly
advantageous for a large-scale apparatus to perform a swinging
movement at a smaller amplitude or angle such that the cables
connected to the swinging device, for example for information
communication, are also moved in a smaller amplitude. In an
embodiment, the slip ring may be swung in a reciprocating way in a
range less than or equal to 150 degrees, or less than or equal to
120 degrees, or less than 100 or equal to degrees, or less than or
equal to 90 degrees, or less than or equal to 70 degrees, or less
than or equal to 60 degrees, or even in a much smaller range, to
perform a scan and inspection of whole or part of an object to be
inspected.
[0026] According to an embodiment, the data acquisition sub-system
includes a plurality of rows of detectors or a detector array 3
that are arranged to cover a certain detection area or preset
detection area. The detection area may be set according to actual
situations. Detector units are arranged at a regular spacing, or
arranged at an irregular spacing. The plurality of rows of
detectors 3 are arranged to collect projection signals from a
sector-shaped X-ray beam. The data acquisition sub-system further
includes a read circuit and a logic control unit for converting the
projection signals into projection data. The detectors may be solid
detectors, scintillator detectors, gas detectors or semiconductor
detectors.
[0027] The plurality of rows of detectors may be fixed on the
support device 4, such as the rotatable slip ring. A larger amount
of projection data collected by the plurality of rows of detectors
during scanning may be communicated to back-end data processor
through optical cables or wires. According to the embodiment,
communication through cables enables higher transmission rate,
higher signal-to-noise ratio and stronger signal transmission
interference resistance. Meanwhile, technical difficulties and cost
for the data acquisition may be largely reduced.
[0028] According to an embodiment, the support device 4 may be a
circular slip ring 4, as shown in FIGS. 1 and 2. The X-ray
generator 1 and the plurality of rows of detectors 3 are arranged
on the slip ring and spaced from each other by 180 degrees, for
example, fixed on the slip ring 4 to be opposite to each other with
respect to the centre of the slip ring 4. The detectors 3 may be
fixed on an inner side of the slip ring, as shown in FIG. 2. In
FIG. 2, a flare angle of the sector-shaped X-ray beam and an
effective detecting area of the plurality of rows of detectors may
be determined depending on a size of a desired region to be imaged
by X-ray scanning. It is appreciated by those skilled in the art
that, according to embodiments of the present invention, although
scan is performed by the reciprocating swinging movement of the
X-ray generator 1 and the corresponding detectors 3 within 180
degrees, a desirable inspection result can be obtained to meet
actual requirements according to the scanning signals.
[0029] According to an embodiment, an electrical driving system is
provided to power the slip ring 4, so as to control the slip ring 4
to rotate within a certain amplitude/angle. Meanwhile, the X-ray
generator 1 is controlled to emit pulsed X-rays 2 at a constant
frequency, and the plurality of rows of detectors are driven to
collect projection data.
[0030] According to an embodiment, it is particularly advantageous
to utilize an eccentric weight distribution of the apparatus to
perform scanning in a single-pendulum movement. Specifically, for
example, since the X-ray accelerator 1 is heavier, the center of
gravity of the whole slip ring is nearer the X-ray accelerator 1
than the detectors, i.e., offset from the circle center of the slip
ring. With this configuration, a single-pendulum type slip ring is
created. Assuming a distance between the center of gravity and the
circle center of the circle slip ring is L, a swinging period is
T=2.pi. {square root over (L/g)}. With a less power from the
electrical driving system, the slip ring 4 may swing periodically
at a constant amplitude. With the embodiments of the present
invention, nature energy due to gravity and the principle of
movement of a single-pendulum are utilized to eliminate complex
driving mechanism and to achieve a reciprocating swinging movement
of the slip ring with a small driving force so that the slip ring 4
is swung at constant amplitude. In addition, the X-ray source 1 and
the detectors 3 are associated to operate under control of a clock,
which leads to a simplified control device and thus enables the
slip ring 4 to have a simple and compact structure, saving cost.
According to the embodiment of the present invention, the slip ring
4 is configured to have an center of gravity offset from its circle
center and thus may perform a single-pendulum movement under a
small driving force, which may not only simplify driving device for
the apparatus, but also facilitate to combine the single-pendulum
movement of the slip ring 4 with emitting operation of X-ray
generator, such that the apparatus may determine and record time of
each emitting operation, and calculate the scanning angle
corresponding to the time of emitting operation. As such, the whole
apparatus may be significantly simplified in structure, produced at
low cost and improved to have an increased reliability, achieving
great economic interest/effect. It is a huge commercial advantage
with respect to construction and operation for an apparatus with a
large volume and huge weight that a rather small driving force is
only needed to achieve scanning operation.
[0031] According to an embodiment of the present invention, the
accelerator is triggered to emit X-ray at a constant frequency,
instead of being triggered through a grating scale due to an
irregular angular velocity of a swinging movement of the grating
scale, and the data acquisition sub-system is also configured to
collect the projection data at the same frequency.
[0032] According to an embodiment, the slip ring 4 may be driven to
move at a substantially constant linear velocity or angular
velocity. That is, during most of travel of the reciprocating
movement, the X-ray accelerator 1 and the data acquisition
sub-system 3 are supported by the slip ring to rotate at a constant
velocity, except performing acceleration and deceleration movements
near either end of the travel. During this, the X-ray accelerator 1
emits X-ray 2 at a constant period, performing inspection. The slip
ring 4 may be driven to perform a reciprocating movement at other
velocities, which may be set by those skilled in the art as
required.
[0033] According to an embodiment, the CT apparatus further
includes a carrier 5 configured to carry the object 6 to be
inspected to pass through an inspection region defined by the X-ray
generator and the data acquisition sub-system. The carrier 5 may
move linearly. For example, the carrier 5 may move linearly in two
directions, i.e., lifting movement in an up-down direction and
translation movement in a fore-and-aft direction. The lifting
movement is provided to facilitate placement of the container 6
onto the carrier 5. Specifically, the carrier 5 may firstly descend
to a suitable level, and then, after placement of the container 6
onto the carrier 5, lift up to a desired level where CT scan may be
performed. Then, the carrier 5 translates to convey the container 6
through the CT scanning region at a constant velocity, completing a
CT scan procedure. The translation velocity is determined according
to period of the swinging movement of the slip ring and desired
reconstruction image quality.
[0034] According to an embodiment, the CT apparatus further
includes a control sub-system configured to control movement of the
swinging support device 4 and operation of the X-ray generator and
the data acquisition sub-system. The control sub-system is
configured to control parts of the CT apparatus to cooperate with
one another.
[0035] According to an embodiment, the CT apparatus further
includes a data processing sub-system, configured to process
projection data obtained by the data acquisition sub-system and
reconstruct a three-dimension image of the object. The data
processing sub-system may be, for example, a data processing
computer for processing data, i.e., processing projection data
obtained by the data acquisition sub-system, reconstructing the
three-dimension image of the object, and showing the image on a
display. The data processing sub-system may also be configured to
control operations of the whole apparatus, including control of
mechanical operation, control of electrical operation, control of
safety chain, and the like. That is, when the CT apparatus is
provided with the control sub-system and the data processing
sub-system, they may be integrated together. The computer may be a
single PC of high-performance, or a work station or computer group.
The display may be a CRT display, or a liquid crystal display.
[0036] According to an embodiment, the control, data transmission,
image reconstruction, and data processing of the whole apparatus
are performed by a work station. Scan controlling data, position
data and projection data are inputted to the work station by the
data acquisition system and reconstructed therein to generate a
transmission image, a tomographic image and a three-dimension image
of the object, which are displayed on the display.
[0037] In addition, in the CT apparatus according to an embodiment
of the invention, the projection data may be reconstructed by using
a weighting function in combination with a conical beam filtering
reverse projection method to generate a three dimension tomographic
image, or reconstructed by combining an iteration method with the
filtering reverse projection method.
[0038] According to the embodiment, data processing technology used
in the CT apparatus includes hardening and scattering correction,
metal artifact correction, and image processing and mode
identification. In the low-angle self-swinging type, large-scale
multi-slice spiral CT apparatus, since the X-ray accelerator 1 is
used as an X-ray source and the X-ray beams are polychromatic,
rather than monochromatic, a hardening effect occurs. The CT
apparatus works based on X-ray transmission attenuation, however
there is also a scattering effect in practice. Further,
corresponding image processing and mode identification
technologies, such as image enhancing technology, marginal check
and computer-aided diagnosis, are also applied in the CT apparatus
according to the embodiment of the present invention.
[0039] According to an embodiment of the present invention, in
order to achieve accurate image reconstruction, the X-ray imaging
system, i.e., the X-ray generator 1 and the data acquisition
sub-system 3, may measure or calibrate following parameters of the
apparatus: a distance T from the X-ray source point S to the
detector, the position of the rotating center O of the slip ring,
and a distance T.sub.1 from the rotating center O to the detector,
in which a connection line between the X-ray source point S and the
rotating center O is perpendicular to a surface of the detector
array, as shown in FIG. 2. Further, the X-ray imaging system may
measure or calibrate a angle parameter of the position where the
X-ray source point S is located at a time when the X-ray generator
emits X-ray, and sizes of the plurality of detectors including a
physical size of each detector and a size of the detector array. It
is appreciated by those skilled in the art that an image of the
inspected object may be produced based on the detected signals by
using acknowledge in prior art.
[0040] In the low-angle self-swinging type, large-scale multi-slice
spiral CT apparatus according to embodiments of the present
invention, the X-ray generator 1 and the plurality of rows of
detectors 3 are used to scan the object to be inspected through the
reciprocating rotation movement within or not greater than 180
degrees and linear movement of the carrier with the object thereon,
thereby achieving the whole scanning process. The X-ray source thus
scans a container along a scanning path of spiral folding line 9.
FIG. 3 shows a scanning path of the X-ray source, in which the
startup point of the X-ray source is denoted by point 8. In the
embodiment, the CT apparatus utilizes a scanning mode of
reciprocating rotation movement and wire transmission mode of X-ray
projection data, and thus is simplified in complexity, thereby
reducing technical difficulty and manufacturing cost. Further, the
self-swinging rotating mode and scanning at a constant interval may
also simplify the control of the apparatus, in which time of
emitting may be automatically determined and recorded and thus a
scanning angle may be calculated. Also, the scanning mode according
to the embodiment of the present invention may allow irradiation
dose of the X-ray source imposed onto the inspected object during
scanning may be largely reduced. The CT apparatus according to the
embodiments of the present invention thus has a very high market
application potentiality.
[0041] Purposes, technical solutions and advantageous effects of
the present invention have been further illustrated in the above
specific embodiments. It should be understood that the above
description is merely used to illustrate specific embodiments of
the present invention, but not to limit the present invention. All
of changes, equivalent alternatives, improvements, made within
principles and spirit of the disclosure, should be included within
the scope of the present invention.
* * * * *