CN219915424U - CT scanning system - Google Patents
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- CN219915424U CN219915424U CN202223516661.9U CN202223516661U CN219915424U CN 219915424 U CN219915424 U CN 219915424U CN 202223516661 U CN202223516661 U CN 202223516661U CN 219915424 U CN219915424 U CN 219915424U
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Abstract
本实用新型涉及一种CT扫描系统，该扫描系统包括至少一个射线源组，用于向被扫描物体发射射线，每个射线源组包括多个射线源，多个射线源在同一扫描平面内彼此间隔布置并且具有不同的射线张角方向；以及至少一个探测器，与至少一个射线源组一一对应地相对设置，每个探测器接收从对应的射线源组发射的并且透射通过被扫描物体的射线，其中，至少一个射线源组在扫描过程中围绕被扫描物体旋转以在多个旋转角度上对被扫描物体进行扫描，并且在同一旋转角度处，每个射线源组中的多个射线源依次发射射线束。
The utility model relates to a CT scanning system. The scanning system includes at least one ray source group for emitting rays to a scanned object. Each ray source group includes a plurality of ray sources. The plurality of ray sources are in the same scanning plane with each other. arranged at intervals and having different ray angle directions; and at least one detector, arranged opposite to at least one ray source group in one-to-one correspondence, each detector receiving the rays emitted from the corresponding ray source group and transmitted through the scanned object. Rays, wherein at least one ray source group rotates around the scanned object during the scanning process to scan the scanned object at multiple rotation angles, and at the same rotation angle, multiple ray sources in each ray source group A beam of rays is fired in sequence.
Description
Technical Field
The utility model relates to the technical field of CT imaging, in particular to a CT scanning system.
Background
The CT scanning technology can measure the ray projections of different angles of an object, and clearly, accurately and intuitively display the structure, the composition, the material and the defect condition of the inside of the detected object in a two-dimensional or three-dimensional image mode through a proper imaging algorithm, so that the CT scanning technology not only becomes an indispensable effective means for medical clinical diagnosis analysis and focus determination, but also gradually becomes an important tool in the fields of industrial nondestructive detection, material tissue analysis, cargo/vehicle safety inspection and the like.
Individual differences may exist between CT systems in different application scenarios, but the basic structures are substantially the same. A typical CT scanning system consists of a radiation source, a detector, a scanning and control device, a data acquisition and processing device, an image reconstruction and display device, and the like.
Disclosure of Invention
In existing CT systems, the number of sources and detectors is often the same, and the radiation from each source impinges on the object being examined, passes through the object and is received by the corresponding detector, and the field of view of the image in such CT scanning systems is limited by the size of the system and the angle of the radiation. If a larger imaging field of view is to be obtained under complete data conditions, it is generally chosen to enlarge the angle of opening of the source and increase the detector size simultaneously, or to increase the distance between the source and the detector, while keeping the overall size of the system unchanged. The former scheme can lead to image quality reduction due to the condition that the radiation source beam current has dose angular distribution, and the latter scheme can avoid the condition that the image quality is reduced due to the fact that the radiation source beam current has dose angular distribution with a large opening angle, but can lead to the increase of the whole size of the system, and inconvenience is brought to the design, construction, radiation protection, construction, maintenance and the like of equipment.
In order to expand the imaging field of view without increasing the detector size and system size, the present utility model proposes a CT scanning system comprising: at least one radiation source set for emitting radiation to the scanned object, each radiation source set comprising a plurality of radiation sources, the plurality of radiation sources being arranged at intervals from each other in the same scanning plane and having different radiation opening angle directions; and at least one detector disposed opposite to the at least one radiation source group in a one-to-one correspondence, each detector receiving radiation emitted from the corresponding radiation source group and transmitted through the scanned object, wherein the at least one radiation source group rotates around the scanned object during scanning to scan the scanned object over a plurality of rotation angles, and the plurality of radiation sources in each radiation source group sequentially emit radiation beams at the same rotation angle.
According to some embodiments, during the scanning, the at least one detector rotates in synchronization with the at least one radiation source group.
According to some embodiments, the energy and/or the angular extent of the radiation beams of the plurality of radiation sources in each radiation source group is the same or the energy and/or the angular extent of the radiation beams of the plurality of radiation sources in each radiation source group is different.
According to some embodiments, the plurality of radiation sources in each radiation source group are arranged at intervals in a tangential direction of the rotation direction within the same scan plane.
According to some embodiments, the plurality of radiation sources in each radiation source group are arranged in an arc shape and a linear shape along a tangential direction.
According to some embodiments, each radiation source group is formed as a multi-focal distributed radiation source or comprises a plurality of independent radiation source modules.
According to some embodiments, each detector of the at least one detector is a single row detector or a plurality of rows of detectors; and each detector is linear or arcuate.
According to some embodiments, the beam energies of the plurality of radiation sources in each radiation source group are arranged to decrease sequentially from the middle to the sides of the arrangement of the plurality of radiation sources.
According to some embodiments, the CT scanning system further comprises a control device that controls the number and position of radiation sources emitting radiation in each radiation source set according to the size of the scanned object.
According to some embodiments, the detector crystals in each of the at least one detector are configured to be independently rotatable such that when the plurality of radiation sources in each radiation source set sequentially emit radiation beams, the radiation receiving face of the detector crystal in the corresponding detector can be adjusted to be perpendicular to the radiation beam of the respective radiation source.
According to some embodiments, the CT scanning system further comprises a control device that controls the at least one radiation source set to rotate around the scanned object such that radiation emitted by the at least one radiation source set covers each point in the scanned object over a range of at least 180 degrees.
According to some embodiments, the control means controls the plurality of radiation sources in each radiation source group to sequentially emit radiation in a time-sharing on and off manner at each rotation angle.
According to some embodiments, the CT scanning system comprises two or more groups of radiation sources, the control means controlling the two or more groups of radiation sources to emit radiation simultaneously at each rotation angle, and controlling the plurality of radiation sources within each group of radiation sources to emit radiation sequentially in a time-shared on and off manner.
According to some embodiments, the CT scanning system further comprises a data acquisition and processing device receiving data acquired by the detector, integrating information for image reconstruction and generating projection data, wherein the data acquisition and processing device distinguishes data based on rays of different ray sources in the same ray source group by receiving time or using the marker signal.
According to some embodiments, the data acquisition and processing device receives the data acquired by the detector in a time-shared manner.
According to some embodiments, the CT scanning system further comprises an image analysis and reconstruction device that processes the projection data generated by the data acquisition and processing device to generate a two-dimensional or three-dimensional image of the scanned object, wherein the image analysis and reconstruction device performs image rearrangement on data from a plurality of radiation sources in the same radiation source group and redundancy processing on overlapping projection data generated by the plurality of radiation sources in the same radiation source group prior to generating the two-dimensional or three-dimensional image of the scanned object.
According to some embodiments, the image analysis and reconstruction device performs image reconstruction using an analytical reconstruction algorithm or an iterative reconstruction algorithm.
Drawings
Fig. 1 shows a schematic view of an imaging field of view calculation of a prior art CT scanning system.
Fig. 2 shows a schematic structural diagram of a CT scanning system according to an embodiment of the present utility model.
Fig. 3A-3C show schematic structural views of a CT scanning system with three different arrangements of radiation sources according to an embodiment of the present utility model.
Fig. 4A and 4B show schematic views of imaging fields of view of a prior art CT scanning system and a CT scanning system according to an embodiment of the present utility model, respectively.
Fig. 5A and 5B show schematic dimensional views of a prior art CT scanning system and a CT scanning system according to an embodiment of the present utility model, respectively, for the same ray angle and imaging field of view.
Detailed Description
Hereinafter, embodiments of the present utility model will be described in detail with reference to the accompanying drawings. The following detailed description and the accompanying drawings are provided to illustrate the principles of the utility model. The solutions described in the following embodiments do not represent all solutions of the utility model, but are merely examples of systems of the various aspects of the utility model that are referred to in the appended claims. The scope of the utility model is defined by the claims.
In the following, the same reference numerals in different drawings denote the same or similar elements unless otherwise indicated.
In the following description, a scan plane refers to a plane in which a cross section of an object to be scanned is located when the CT scanning system scans each cross section of the object to be scanned. The imaging field of view refers to the maximum extent that the beam of a CT scanning system can cover in one scan plane. In addition, the term "ray angle" referred to hereinafter refers to the angle of the radiation beam emitted by the radiation source in the scan plane.
Prior art CT scanning systems typically include an equal number of sources and detectors, one for each, with each source emitting radiation that impinges on the scanned object, passes through the scanned object and is received by the corresponding detector. In the following, a prior art CT scanning system is described by way of example with a CT scanning system comprising a single radiation source and a single detector. Fig. 1 discloses a schematic view of a CT system according to the prior art, wherein S is a radiation source and D is a detector, and a radiation beam (an opening angle 2 y in a scanning plane, i.e. a plane in which the paper surface in fig. 1 is located) emitted by the radiation source S is received by the detector D after being transmitted through an object (not shown in the figure) to be scanned. During scanning of the scanned object, the source S and detector D can be rotated synchronously about the center of rotation O to produce scan data for a plurality of angles. Thus, a CT scanning system may have an imaging field of view as indicated by the gray shaded portion in FIG. 1, the center of the imaging field of view being the center of rotation O, R being the radius of the imaging field of view, i.e., the maximum radius of the scanned object portion that the rays of the CT scanning system can cover in the scan plane. The geometric relationship shown in fig. 1 is easily obtained, and the imaging field radius R of the CT scanning system is: r=so·sin (γ), where SO is the distance of the source S from the center O of the imaging field of view.
As can be seen from the above equation, if an object with a larger size is to be scanned, the R needs to be increased, which can be generally achieved by two schemes: firstly, the SO is kept unchanged, the gamma is increased, namely, under the condition that the overall size of the system is unchanged, the opening angle of the ray beam is increased, and the size of the detector is required to be synchronously increased at the moment SO that the ray beam can completely cover the scanned object and can be detected by the detector; the second solution is to keep gamma unchanged and increase SO, that is, keep the ray angle of the ray source unchanged, and increase the distance from the ray source to the center of the imaging field of view to achieve the purpose of increasing the imaging field of view, which obviously increases the overall size of the system.
In X-ray radiation imaging of objects of relatively large dimensions (e.g. having an outer diameter of more than 1 meter), relatively high energy radiation (typically having a radiation energy of more than 1MeV, e.g. 3MeV, 7MeV, 9MeV or up to tens of MeV) is required to penetrate the object and obtain information therein. However, the higher the radiation energy, the more non-negligible the effect of the radiation dose angular distribution. The radiation dose angular distribution means that when the beam angle of the radiation source is large, the radiation dose in the edge region of the angle is attenuated more than in the central region, the portion of the object irradiated by these rays in the edge region may result in poor image quality due to the radiation dose being too small. Such as a 9MeV electron linac, has an X-ray beam uniformity of only 55% at a distance of 0 ° from the 7.5 ° angular position, and the radiation in these regions may not penetrate the object after striking the object or may be annihilated in the noise floor of the detector due to too small a dose after penetration, resulting in poor quality of the final reconstructed image. Therefore, the first solution described above (increasing the beam angle) is not suitable for CT scanning systems for high energy rays. The second scheme increases the distance from the ray source to the object without changing the ray angle, so that the image quality degradation caused by the dose angle distribution of the ray source can be avoided, but the distance from the ray source to the center of an imaging visual field is increased, the whole size of the system is increased, and inconvenience is brought to the design, construction, radiation protection, construction, maintenance and the like of equipment. Therefore, neither of the above two solutions is suitable for CT imaging with high energy and large field of view.
In order to more conveniently scan larger sized objects, the present utility model proposes a large field-of-view CT scanning system adapted to use high energy rays, which is capable of expanding the imaging field of view without increasing the size of the detector and system. Specifically, a CT scanning system according to an embodiment of the present utility model includes: at least one radiation source set for emitting radiation to the scanned object, each radiation source set comprising a plurality of radiation sources spaced from each other in the same scan plane and having different angular directions of radiation; and at least one detector disposed in one-to-one correspondence with the at least one radiation source set, each detector receiving radiation emitted from the plurality of radiation sources of the corresponding radiation source set and transmitted through the scanned object, wherein the at least one radiation source set is configured to rotate about the scanned object during scanning to scan the scanned object over a plurality of rotation angles, and the plurality of radiation sources in each radiation source set sequentially emit radiation beams at the same rotation angle. The plurality of ray sources in each ray source group sequentially emit ray beams at the same rotation angle, and imaging fields of the plurality of ray sources in the same ray source group can be spliced with each other, so that the overall irradiation area of the system can be enlarged, and large-field scanning of a large object is realized.
A CT scanning system according to an embodiment of the present utility model is described in detail below with reference to the accompanying drawings. Fig. 2 shows a schematic view of a CT scanning system according to an embodiment of the utility model. As shown in fig. 2, the CT scanning system comprises a radiation source group S for emitting radiation towards an object to be scanned, and a detector D for receiving radiation emitted by the radiation source group S and transmitted through the object to be scanned, wherein the object to be scanned is placed between the radiation source group S and the detector D via a carrier means (not shown in the figure).
The radiation source set S comprises a plurality of radiation sources S for emitting radiation 1 、S 2 、S 3 、S 4 、S 5 The plurality of radiation sources S 1 、S 2 、S 3 、S 4 、S 5 Are spaced apart from each other in the same scan plane but the angular directions of the beam streams are different. Here, the scanning plane is a plane in line with the paper surface in fig. 2. In addition, each ray source S 1 、S 2 、S 3 、S 4 、S 5 Has the same opening angle gamma and has the same energy. The detector D is arranged in the scanning plane and is connected with a plurality of ray sources S 1 、S 2 、S 3 、S 4 、S 5 Arranged opposite to each other, wherein each of the radiation sources S 1 、S 2 、S 3 、S 4 、S 5 The angular orientation of the beam streams of the respective radiation sources is set such that the beam streams of the respective radiation sources correspond to the detector D. Here, the term "corresponding to"Generally, each radiation source S 1 、S 2 、S 3 、S 4 、S 5 The projection of the emitted radiation onto the detector falls within the detector length L D Preferably, as shown in fig. 2, the projection of each source is equal to the detector length L D . By setting the angular orientation of the radiation source in this way, it is possible to achieve a radiation coverage of every point in the scanned object with a small angle of rotation of the radiation source.
During the scanning process, the radiation source group S and the corresponding detector D rotate around their rotation centers O to scan the scanned object over a plurality of rotation angles and obtain corresponding projection data. In particular, a plurality of radiation sources S of a radiation source group S at the same rotation angle 1 、S 2 、S 3 、S 4 、S 5 The radiation beams are sequentially emitted to irradiate the scanned object.
Thus, the CT scanning system shown in FIG. 2 has an imaging field of view with a center O (i.e., the center of rotation O described above) and a radius R in the scan plane. Due to multiple radiation sources S 1 、S 2 、S 3 、S 4 、S 5 The imaging fields of view of the individual sources may be stitched to each other within the same scan plane to form a larger imaging field of view than the imaging field of view of any of the individual sources therein (e.g., the dark shaded portion in fig. 2), without the need for changing the distance between the source and the detector and the size of the detector itself. Accordingly, the CT scanning system according to the above-described embodiments can expand the imaging field of view without increasing the system and detector size.
Further, as shown in fig. 2, a plurality of radiation sources S of the radiation source group S 1 、S 2 、S 3 、S 4 、S 5 Are arranged at intervals in the tangential direction of the rotation direction (indicated as a in fig. 2) in the scanning plane. Here, the rotation direction refers to the rotation direction of the radiation source group S and the detector D about the rotation center O. Specifically, the plurality of radiation sources of the radiation source group S may be arranged in a straight line (as shown in fig. 2, 3A, and 3C) and may be arranged in an arc shape (as shown in fig. 3B) along a tangential direction of the rotation direction in the scan plane. In one placeIn some embodiments, a plurality of radiation sources S 1 、S 2 、S 3 、S 4 、S 5 Is arranged on an arcuate rail and the individual radiation sources are arranged to be movable, preferably rapidly, along the rail within a predetermined range (e.g. controlled by a control device described below), so that the imaging field of view can be controlled (enlarged or reduced) by controlling the distance of the individual radiation sources from each other in the case of a defined number of radiation sources. Of course, it should be clear that the interval between the plurality of radiation sources of the radiation source set S should be set so that the radiation emitted from the plurality of radiation sources can cover the entire range of the desired imaging field of view, and it is necessary to avoid a case where the imaging field of view partial range cannot be covered because of the excessive interval.
According to other embodiments, the plurality of radiation sources of the radiation source set S may also be arranged at intervals in other directions, for example, in a direction perpendicular to the rotation plane of the radiation source set S, as long as it is possible to achieve an enlarged imaging field of view on the same scan plane with respect to the case where any single radiation source is present.
The plurality of radiation sources of the radiation source group S may be formed by radiation sources of a distributed multi-focal structure (which have the same focal number as the number of radiation sources in the group), or may be a plurality of independent radiation source modules (the number of modules is equal to the number of radiation sources in the radiation source S). The radiation beam emitted from each radiation source may be a fan beam or a cone beam.
Further, as shown in fig. 2, the radiation source group S includes an odd number of radiation sources, but the present utility model is not limited thereto. According to other embodiments, the set of radiation sources S may include an even number of radiation sources (as shown in FIGS. 3A-3C). Also, in the embodiment of fig. 2, the radiation source set S comprises 5 radiation sources. However, the present utility model is not limited thereto. According to other embodiments, the radiation source set S may include more or fewer radiation sources, as long as the number of radiation sources is 2 or more. Furthermore, the plurality of radiation sources in the radiation source set S may be symmetrically arranged as shown in fig. 2, or may be asymmetrically arranged (as shown in fig. 3C).
In addition, the actual embodiment shown in FIG. 2In an embodiment, a plurality of radiation sources S in a radiation source set S 1 、S 2 、S 3 、S 4 、S 5 The beam angle and energy of the beam are the same to simplify the calculation required to process the data for image reconstruction, although the utility model is not limited thereto, according to other embodiments, a plurality of sources S 1 、S 2 、S 3 、S 4 、S 5 The individual ray angle sizes and/or energies of (a) may be different. In some embodiments, a plurality of radiation sources S in a radiation source set S 1 、S 2 、S 3 、S 4 、S 5 The beam energy of the beam can be sequentially reduced from the middle beam source to the two side beam sources in the arrangement of a plurality of beam sources (for example, the energy is S 3 >S 2 ＝S 4 >S 1 ＝S 5 ) So that the radiation source S with smaller energy is used 1 、S 2 、S 4 、S 5 Can also eliminate or mitigate the radiation source S due to high energy 3 Is adversely affected by the non-uniform angular distribution of the radiation dose. Multiple radiation sources S 1 、S 2 、S 3 、S 4 、S 5 The radiation angle of each of the detectors is set to be at least capable of covering the whole radiation receiving surface of the corresponding detector, so that the detection efficiency is improved.
In the embodiment shown in fig. 2 and 3A-3C, the arrangement of detector crystals in detector D is rectilinear, but according to other embodiments the arrangement of detector crystals may also be arcuate. The detector D may be a single-row detector or a multi-row detector. Furthermore, each detector crystal in detector D may be independently rotatably configured such that each detector crystal of detector D is capable of adjusting its respective detection plane in real time to be perpendicular to the received radiation beam as any one of the radiation sources in the set of radiation sources S emits the radiation beam. In other words, when the plurality of radiation sources in the radiation source set S sequentially emit radiation beams, each detector crystal is also correspondingly deflected, so that when any one of the radiation sources in the radiation source set S emits a radiation beam, the detection surface of the detector crystal is opposite to the any one of the radiation sources.
Further, as described above, during scanning, the radiation source group S and the detector D are rotated about the rotation center O to scan the scanned object over a plurality of rotation angles. To achieve rotation of the radiation source set S and the detector D, the CT scanning system may comprise a rotational support means, as part B in fig. 2. The rotary support means B may be a slip ring, swivel or bracket. The radiation source set S and the detector D may be rotated around the scanned object by rotating the support means B such that the radiation of the radiation source set S covers each point in the scanned object over a range of at least 180 degrees. The radiation source set S may be rotated by a reciprocating rotation manner or a unidirectional continuous rotation manner. Furthermore, the scan trajectory of the source set S may be circular, helical, linear, saddle-shaped or other scan trajectory.
Furthermore, in the embodiment shown in fig. 2, the detector D rotates synchronously with the radiation source set S during scanning, which makes it possible to minimize the size of the detector D. But the present utility model is not limited thereto. According to other embodiments, only the set of radiation sources S is rotated and the detector D is not rotated during scanning.
The advantages of the present utility model are described below by comparing in detail the sizes of imaging fields of view of a prior art CT scanning system and a CT scanning system according to an embodiment of the present utility model. For ease of illustration, a prior art CT scanning system including a single source and a single detector is illustrated as compared to the CT scanning system shown in FIG. 2.
Fig. 4A shows a schematic diagram of a prior art CT scanning system. As shown in FIG. 4A, the focal point of the radiation source of the CT scanning system is S 0 The detector is D, and the detector length is L D The source and detector can be rotated synchronously about the center of rotation O to acquire projection data at different angles of rotation. Focal spot S of radiation source 0 Distance from rotation center O is L SO Distance from the center of the detector is L SD . The gray circular area in fig. 4A is the imaging field of view of the CT scanning system. According to the geometric relationship in fig. 4A, the imaging field radius Ra is:
in the CT scanning system according to the above embodiment of the present utility model, the description will be made with the total length of the radiation source and the detector length being equal, that is, when L S ＝L D In this case, according to the geometric relationship in fig. 4B, the imaging field of view radius is:
by combining the above formula (1), it is possible to obtain:
from the above, R is b ＞2·R a . That is, a CT scanning system according to an embodiment of the present utility model employing an arrangement of multiple radiation sources corresponding to a single detector has an imaging field of view radius that is more than 2 times enlarged relative to existing CT scanning systems in which a single radiation source corresponds to a single detector, while the overall size of the system and the size of the detector may remain unchanged. It can be seen that a CT scanning system in accordance with embodiments of the present utility model is capable of expanding the imaging field of view without increasing the size of the detector and system.
Further, from another perspective, the CT scanning system of the above-described embodiments of the present utility model may reduce the overall system size and detector size relative to the CT scanning systems of the prior art described above, while maintaining the radiation source opening angle and imaging field of view unchanged. The specific comparison is as follows.
Fig. 5A and 5B show schematic dimensional views of a prior art CT scanning system and a CT scanning system according to the above-described embodiment of the present utility model, respectively, with the same radiation angle and imaging field of view. Here, it is assumed that the sizes of the ray angles of the single ray sources of the CT scanning system of the related art and the CT scanning system according to the above-described embodiment of the present utility model are the same, for example, 2 γ, and that the diameters of the imaging fields of view of both are the same, for example, R. From the geometric relationships in fig. 5A and 5B, the detector length of the prior art CT scanning system in fig. 5A is:
(the detector length of the CT scanning system according to the above-described embodiment of the utility model in FIG. 5B is (again assuming here that the source length is equal to the detector length):
L D ＝2·R (L S ＝L D when).
As can be obtained from the above two formulas,
it can be seen that the CT scanning system according to embodiments of the present utility model can greatly shorten the detector length relative to the CT scanning system of the prior art.
Further, in terms of system size, in FIG. 5A, the source S 0 The distance to the center of rotation is: l (L) SO R/sin (gamma), 2 gamma < 90 DEG, irrespective of the angular distribution limit, soHowever, the CT scanning system according to the embodiment of the present utility model is not limited thereto, since a plurality of radiation sources are used. Therefore, the CT scanning system according to the embodiment of the utility model can reduce the size of the system as much as possible.
From the above comparison, it can be found that the CT scanning system according to the embodiment of the present utility model can expand the imaging field of view without increasing the overall size of the detector and the system, compared with the prior art, and is thus particularly suitable for scanning and imaging large-sized objects by using high-energy rays. In addition, without increasing the imaging field of view relative to the prior art, the overall size of the detector and system can be reduced without affecting image quality.
Furthermore, in the foregoing embodiments of the present utility model, the CT scanning system includes a single radiation source set and a single detector corresponding to the single radiation source set. However, the present utility model is not limited thereto. According to other embodiments, a CT scanning system may include a plurality of ray source sets and include a plurality of detectors in one-to-one correspondence with each ray source set. The source sets may be source sets as described in any of the previous embodiments, and the detectors may be detectors as described in any of the previous embodiments, the specific configuration of each source set and each detector will not be described again. Thus, a CT scanning system comprising a plurality of ray source sets and a corresponding plurality of detector sets may also enlarge the imaging field of view without increasing the system and detector size, and may reduce the overall size of the detector and system without affecting the image quality without increasing the imaging field of view relative to the prior art.
The plurality of radiation source sets may be two or two radiation source sets. The plurality of radiation source sets may be sequentially arranged in the rotation direction, and correspondingly the plurality of detectors may be sequentially arranged in the rotation direction opposite to the plurality of radiation source sets in one-to-one correspondence. Further, while rotating around the scanned object, the plurality of ray source groups and the plurality of detector groups are rotated in synchronization, so that the scanned object can be scanned over a plurality of rotation angles. Because of the adoption of a plurality of ray source sets and a plurality of corresponding detectors, the CT scanning system according to the embodiment can acquire more scanning data at the same rotation angle, so that the imaging speed can be improved, and the quality of a reconstructed image can be improved.
Next, a scanning manner of the CT scanning system according to the present utility model is described. The CT scanning system according to an embodiment of the present utility model may further include a control device that may control the at least one radiation source group to rotate around the scanned object such that the radiation emitted by the at least one radiation source group covers each point in the scanned object over a range of at least 180 degrees. In case the CT scanning system comprises only a single radiation source set, as in the CT scanning system shown in fig. 2, the control means may control the radiation source set S to rotate around the scanned object (or the rotation center O) such that the radiation emitted from the plurality of radiation sources of the radiation source set S may surround each point of the scanned object over a range of at least 180 degrees, thereby obtaining overall scan data and improving the quality of the reconstructed image.
In addition, during the scanning process, the control device may also control the plurality of radiation sources of the radiation source set S to sequentially emit radiation at each rotation angle in a time-sharing on and off manner. Specifically, the control means stops the rotation after controlling the plurality of radiation sources of the radiation source set S to rotate at a predetermined angular amplitude to a first rotation angle at which the radiation sources S are turned on for a first period of time 1 And turning off other sources to cause the source S 1 Emitting radiation, turning off the radiation source S during a second period of time 1 And other sources and turning on source S 2 Emitting radiation, turning off the radiation source S during a third period of time 2 And other sources and turning on source S 3 Emitting radiation; alternatively, the source S is turned on for a first period of time 3 And turning off other sources to cause the source S 3 Emitting radiation, turning off the radiation source S during a second period of time 3 And other sources and turning on source S 2 Emitting radiation, turning off the radiation source S during a third period of time 2 And other sources and turning on source S 4 Radiation is emitted. And so on, until each radiation source has undergone radiation emission for a predetermined period of time, the control device controls the radiation source set S to rotate to the next rotation angle in a predetermined angle amplitude and stop rotating, and controls the plurality of radiation sources of the radiation source set S to sequentially emit radiation at the next rotation angle in a similar time-sharing on and off manner. And so on until the radiation source set S is rotated through a predetermined rotation angle, for example 180 degrees, etc., the scanning process is completed.
In the scanning process, the control device controls the plurality of ray sources of the ray source set S to rotate to a certain rotation angle in a preset angle range, then the ray source set S stops rotating, and the plurality of ray sources of the ray source set S sequentially emit rays to scan an object to be scanned. However, the scanning process of the present utility model is not limited thereto, and the plurality of radiation sources of the radiation source group S may be rotated while emitting beams. For example, the multiple sources of the source set S can sequentially emit beams (e.g., pulse out beams) at extremely high speeds, while the rotation speed of the source set S around the scanned object is slow (e.g., the rotation speed of the slip ring is slow in the case of rotating the source set S by the slip ring). Thus, when the radiation source set S starts to rotate around the scanned object, the plurality of radiation sources in the radiation source set S start to sequentially emit beams once at a very fast speed, and the radiation source set S rotates around the scanned object only by a very small angle, and the angle change at the beginning of the beam emission with respect to the end of the beam emission of all the radiation sources of the radiation source set S is very small, which corresponds to that the plurality of radiation sources sequentially emit beams at the same rotation angle. Thereby, there is still a space between the positions at which the plurality of radiation sources of the radiation source group S actually emit beams, and an increased imaging field of view can still be ensured with respect to the case in which only a single radiation source emits beams.
In some embodiments, the control device may control the number and location of radiation sources emitting radiation according to the size of the scanned object. For example, referring to FIG. 4B, when the size of the scanned object is the dark gray region size, only the source S may be controlled during scanning 3 Emitting radiation; the source S being controllable during scanning when the size of the scanned object is the size of the light grey zone 1 To S 5 Emitting radiation; when the size of the scanned object is between the two, the radiation source S can be controlled only during the scanning process 1 、S 3 And S is 5 Radiation is emitted. Therefore, the number and the positions of the ray sources emitting rays can be adjusted in real time according to the size of the scanned object through the CT scanning system, the scanning speed can be remarkably improved, and rapid imaging is facilitated. In some embodiments, the size of the scanned object may be obtained by means of, for example, an additional laser scanner, visible light imaging, etc., and fed back to the control device. Here, the size of the scanned object may refer to a distance between two points farthest from the scanned object in a projection in a scan plane.
When the CT scanning system includes two or more radiation source groups, the control device may control the two or more radiation source groups to emit radiation simultaneously at each rotation angle, and control the plurality of radiation sources in each radiation source group to sequentially emit radiation in a time-sharing on and off manner. The specific scanning procedure is similar to the various scanning procedures described above in which a plurality of radiation sources of a single radiation source set S are controlled to scan, except that the plurality of radiation source sets simultaneously rotate around the object to be scanned, each radiation source set simultaneously emits radiation when beam is emitted, but the plurality of radiation sources within each radiation source set sequentially emit radiation. Because different ray source sets correspond to different detectors, a plurality of ray source sets emit rays simultaneously, and the ray sources in each set emit rays in sequence, the scanning efficiency can be improved, and the confusion of data can not be caused.
The CT scanning system of the embodiment of the utility model further comprises a data acquisition and processing device, wherein the data acquisition and processing device receives the data acquired by the detector, integrates the information for image reconstruction and generates projection data. Since the same detector receives rays of a plurality of ray sources corresponding to the ray source group, the positions of the plurality of ray sources may be different, even the ray energy, the opening angle size, etc., and it is necessary to distinguish data based on rays of different ray sources. For this purpose, the data acquisition and processing device of the utility model distinguishes data based on rays of different ray sources in the same ray source group by receiving time or using a marker signal. For example, the data acquisition and processing device receives the data acquired by the detector in a time-sharing acquisition manner, corresponding to the fact that the plurality of ray sources in the ray source group sequentially emit rays in a time-sharing on and off manner in the scanning process. Specifically, under a certain rotation angle, when a first ray source of a plurality of ray sources of a certain ray source set is started and emits rays in a first time period, the detector receives irradiation information of the first ray source, and the data acquisition and processing device receives data acquired by the detector and stores or caches corresponding projection data and related information together; after the first time period is over, the first ray source is closed, the second ray source is opened in the second time period and emits ray beams, the detector receives irradiation information of the second ray source, and the data acquisition and processing device receives data acquired by the detector and stores or caches corresponding projection data and related information together; and so on until after the last radiation source in the radiation source set is turned on and irradiates for a period of time and the corresponding projection data and related scan information are stored or buffered, the radiation source set is rotated to a next rotation angle where the data acquisition and processing device similarly receives the data acquired by the detector and stores or buffers the corresponding projection data and related information, etc., until the radiation source set is rotated through a predetermined angle, such as 180 degrees, etc. In case the CT scanning system comprises a plurality of detectors, the data acquisition and processing device may do the above for each detector simultaneously.
Furthermore, the CT scanning system according to the embodiment of the utility model further comprises an image analysis and reconstruction device which processes the projection data generated by the data acquisition and processing device to generate a two-dimensional or three-dimensional image of the scanned object. Specifically, since projection data from a plurality of radiation sources has different geometric parameters (e.g., the radiation source positions, the source detection distances, the radiation vectors, etc.) for the same radiation source group, it is necessary to perform data rearrangement, i.e., weighted arrangement, of projection data from a plurality of radiation sources in the same radiation source group before performing image reconstruction. In addition, projection data generated by a plurality of ray sources in the same ray source group are overlapped, so that the image analysis and reconstruction device also performs redundancy processing on the projection data of the overlapped area so as to maximally use the collected data and avoid image artifacts. In case the CT scanning system comprises a plurality of sets of radiation sources, the image analysis and reconstruction means may do the above for each set of radiation sources simultaneously.
After data rearrangement and redundancy processing, the projection data has complete reconstruction conditions. The image analysis and reconstruction device can adopt an analytical reconstruction algorithm, such as a filtered back projection reconstruction (FBP) algorithm, or an iterative reconstruction algorithm, such as an Algebraic Reconstruction (ART) algorithm, a joint algebraic reconstruction algorithm (SART), a maximum likelihood estimation (ML), an Ordered Subset Expectation Maximization (OSEM) method, and the like to reconstruct the image.
The foregoing description of the utility model has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the utility model to the precise form described. Many modifications and variations are possible without departing from the spirit of the utility model. The scope of the utility model is defined by the appended claims.
Claims (13)
1. A CT scanning system, comprising:
at least one radiation source set for emitting radiation to an object to be scanned, each radiation source set comprising a plurality of radiation sources arranged at intervals from each other in the same scanning plane and having different radiation opening angle directions; and
at least one detector disposed in one-to-one correspondence with the at least one source group, each detector receiving radiation emitted from the corresponding source group and transmitted through the scanned object,
wherein the at least one radiation source group is configured to rotate around the scanned object during scanning to scan the scanned object over a plurality of rotation angles, and the plurality of radiation sources in each radiation source group sequentially emit radiation beams at the same rotation angle.
2. The CT scanning system of claim 1 wherein the at least one detector rotates in synchronization with the at least one radiation source group during scanning.
3. The CT scanning system of claim 1, wherein,
the energy and/or opening angle of the ray beams of the plurality of ray sources in each ray source group are the same, or the energy and/or opening angle of the ray beams of the plurality of ray sources in each ray source group are different.
4. The CT scanning system of claim 1, wherein,
the beam energy of the plurality of radiation sources in each radiation source group is set to decrease sequentially from the middle to the two sides of the arrangement of the plurality of radiation sources.
5. The CT scanning system of claim 1 further comprising a control device that controls the number and location of radiation sources emitting radiation in each set of radiation sources based on the size of the scanned object.
6. The CT scanning system of claim 1, wherein,
each radiation source set is formed as a multi-focal distributed radiation source or comprises a plurality of independent radiation source modules.
7. The CT scanning system of claim 1, wherein,
the detector crystals in each of the at least one detector are configured to be independently rotatable such that when the plurality of radiation sources in each radiation source set sequentially emit radiation beams, the radiation receiving face of the detector crystal in the corresponding detector can be adjusted to be perpendicular to the radiation beam of the respective radiation source.
8. The CT scanning system of claim 1 further comprising a control device that controls the at least one radiation source set to rotate about the scanned object such that radiation emitted by the at least one radiation source set covers each point in the scanned object over a range of at least 180 degrees.
9. The CT scanning system of claim 8 wherein the control device controls the plurality of sources in each of the source groups to sequentially emit radiation in a time-shared on and off manner at each angle of rotation.
10. The CT scanning system of claim 8 comprising two or more groups of radiation sources, wherein the control device controls the two or more groups of radiation sources to emit radiation simultaneously at each angle of rotation and controls the plurality of radiation sources within each group of radiation sources to emit radiation in sequence in a time-shared manner on and off.
11. The CT scanning system of any of claims 1-10, further comprising a data acquisition and processing device that receives the data acquired by the detector, integrates information for image reconstruction and generates projection data, wherein the data acquisition and processing device distinguishes data based on rays of different sources in the same set of sources by receiving time or using marker signals.
12. The CT scanning system of claim 11 wherein the data acquisition and processing device receives the data acquired by the detector in a time-shared manner.
13. The CT scanning system of claim 11 further comprising an image analysis and reconstruction device that processes the projection data generated by the data acquisition and processing device to generate a two-dimensional or three-dimensional image of the scanned object, wherein the image analysis and reconstruction device performs image rearrangement of data from multiple sources in the same source group and redundancy processing of overlapping projection data generated by multiple sources in the same source group prior to generating the two-dimensional or three-dimensional image of the scanned object.
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| CN116242856A (en) * | 2022-12-28 | 2023-06-09 | 清华大学 | CT scanning system and method |
| CN119575497A (en) * | 2024-12-30 | 2025-03-07 | 同方威视技术股份有限公司 | Radiation inspection system |
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| CN116242856A (en) * | 2022-12-28 | 2023-06-09 | 清华大学 | CT scanning system and method |
| CN119575497A (en) * | 2024-12-30 | 2025-03-07 | 同方威视技术股份有限公司 | Radiation inspection system |
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