CN111657979A

CN111657979A - CT imaging system and imaging method thereof

Info

Publication number: CN111657979A
Application number: CN201910175603.8A
Authority: CN
Inventors: 奚岩
Original assignee: Jiangsu Yiying Medical Equipment Co ltd
Current assignee: Jiangsu Yiying Medical Equipment Co ltd
Priority date: 2019-03-08
Filing date: 2019-03-08
Publication date: 2020-09-15

Abstract

The invention provides a CT imaging system and an imaging method thereof. The CT imaging system is used for CT scanning imaging of a body to be scanned and comprises a plurality of image chains which are annularly arranged on the periphery of the body to be scanned, the body to be scanned and the plurality of image chains can rotate relatively, each image chain comprises a ray source-detector group and collimators which are arranged in one-to-one correspondence with the ray source-detector groups, and the collimators are arranged between the ray sources and the detectors so as to remove scattered rays between the ray source-detector groups and inside the ray source-detector groups. The CT imaging system can simultaneously acquire data of the body to be scanned by arranging the plurality of image chains so as to respectively acquire the complete scanning image and the partial scanning image of the body to be scanned, thereby reducing the scanning time of the CT imaging system, effectively improving the time resolution of the CT imaging system and enabling the CT imaging system to be suitable for scanning and imaging of moving organs or tissues.

Description

CT imaging system and imaging method thereof

Technical Field

The invention relates to a CT imaging system and an imaging method thereof, belonging to the technical field of computed tomography images.

Background

In the conventional CT imaging method, projection data of each angle of a scanned object is acquired by adopting a method of rotating the scanned object or rotating a ray source and a detector, and then a CT image is calculated by a reconstruction algorithm. Conventional CT can be considered as slow CT and therefore the object cannot move any further during the rotation, which would lead to severe motion artifacts in the reconstructed image.

For imaging moving organs or tissues, such as heart imaging, the use of slow CT imaging methods tends to produce more motion artifacts. In order to realize clear imaging of moving organs or tissues, the prior art generally adopts the method of accelerating the scanning speed and improving the time resolution of the CT imaging system. In fact, the fastest CT scan speeds available can reach 3Hz, i.e., three turns are scanned a second. Although the CT scanning speed is greatly improved, the motion artifact cannot be fundamentally eliminated, and the quality requirement of clear imaging of moving organs or tissues cannot be met.

In view of the above, there is a need for an improved CT imaging system and method for imaging the same to solve the above problems.

Disclosure of Invention

The invention aims to provide a CT imaging system and an imaging method thereof, wherein the CT imaging system can be applied to clear imaging of moving organs or tissues and has higher time resolution.

In order to achieve the above object, the present invention provides a CT imaging system for CT scanning imaging of a to-be-scanned object, the CT imaging system includes a plurality of image chains annularly disposed around the to-be-scanned object, the to-be-scanned object and the plurality of image chains can rotate relatively, the image chains include a radiation source-detector set and collimators disposed in one-to-one correspondence with the radiation source-detector set, and the collimators are disposed between the radiation source and the detectors to remove scattered rays between the radiation source-detector set and inside the radiation source-detector set.

In a further improvement of the present invention, N image chains are provided, the N image chains are staggered at a fixed angle on a plane, and the fixed angle between two adjacent image chains is α, α is 360 °/N, and N is greater than or equal to 2.

As a further improvement of the present invention, the collimator includes a first collimator and a second collimator, the first collimator is disposed at two sides of the radiation emitting path of the radiation source for removing scattered radiation between the radiation source-detector group and the radiation source-detector group; the second collimator is arranged close to the detector and is used for removing scattered rays inside the ray source-detector set.

As a further improvement of the invention, the first collimator is a two-dimensional mechanical collimator.

As a further improvement of the present invention, the second collimator is disposed substantially parallel to the detector, and the central axis of the first collimator is substantially perpendicular to the plane of the second collimator and is located on the same straight line with the center of the second collimator.

In order to achieve the above object, the present invention further provides an imaging method for acquiring a CT image by using the CT imaging system, including the following steps:

s1, carrying out full scanning on the body to be scanned, and acquiring a series of segmented projection data of the body to be scanned;

s2, fitting and reconstructing the image based on the series of segmented projection data to obtain a complete scanning image of the body to be scanned;

s3, carrying out partial scanning on the body to be scanned, and acquiring a series of partial projection data of the body to be scanned;

s4, fitting and reconstructing the image based on the series of partial projection data to obtain a partial scanning image of the body to be scanned;

and S5, correcting the full scanning image based on the partial scanning image to acquire a CT image of the object to be scanned.

As a further improvement of the present invention, in step S1, the series of segmented projection data is obtained by rotating several image chains by β degrees relative to the object to be scanned, and β ≧ α.

As a further improvement of the present invention, in step S2, the full scan image is formed by angle-complementarily superimposing a series of segmented scan images after reconstructing the series of segmented projection data into a series of segmented scan images.

As a further improvement of the invention, the series of partial projection data is obtained by rotating a plurality of image chains by gamma degrees relative to the body to be scanned, and gamma < alpha.

As a further improvement of the present invention, the steps S1 and S3 further include: and starting the ray sources arranged at intervals in the plurality of image chains, simultaneously starting all the detectors in the plurality of image chains to acquire ray scattering data of the ray sources, and correcting the segmented projection data in the step S1 and the partial projection data in the step S3 by using the ray scattering data.

The invention has the beneficial effects that: the CT imaging system can simultaneously acquire data of the body to be scanned by arranging the plurality of image chains, effectively reduces the scanning time of the CT imaging system and is suitable for scanning and imaging moving organs or tissues. Meanwhile, a complete scanning image and a partial scanning image of the body to be scanned are respectively obtained through the plurality of image chains, and the complete scanning image is corrected by using the partial scanning image, so that the time resolution of the CT imaging system is improved, the obtained CT image is clearer, and the image quality is higher.

Drawings

FIG. 1 is a schematic diagram of a CT imaging system according to the present invention.

Fig. 2 is a schematic diagram of the combination arrangement of a plurality of image chains in fig. 1.

Fig. 3 is a schematic diagram of the image chain in fig. 2.

Fig. 4 is a schematic flow diagram of an imaging method of the present invention.

Fig. 5a is an angle-time diagram of a data acquisition mode of a conventional CT system.

FIG. 5b is an angle-time schematic of the data acquisition mode of the CT imaging system of the present invention.

FIG. 6 is an angle-time schematic of a portion of the acquired projection data of the CT imaging system of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the aspects of the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.

In addition, it is also to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Referring to fig. 1 to fig. 3, a CT imaging system 100 for CT scanning imaging of a to-be-scanned object is shown. The CT imaging system 100 includes a scanning device 1 and a control device (not shown) electrically connected to the scanning device 1.

The scanning device 1 includes a platform 11, and a plurality of image chains 12 annularly disposed around the platform 11. The object placing table 11 is used for bearing an object to be scanned, and the object placing table 11 and the plurality of image chains 12 can rotate relatively. Further, in a preferred embodiment of the present invention, the object placing table 11 is a rotatable object placing table, that is, the object placing table 11 can drive the object to be scanned to rotate, and scan the object to be scanned simultaneously through the plurality of image chains 12, so as to obtain the segmented projection data/partial projection data of the object to be scanned. In other embodiments, the object stage 11 may be a fixed object stage, and at this time, the image chains 12 may rotate relative to the fixed object stage to scan the object to be scanned at the same time.

In the present invention, N (N is greater than or equal to 2) image chains 12 are provided, the N image chains 12 are staggered at a fixed angle on a plane, and the fixed angle between two adjacent image chains 12 is α, where α is 360 °/N; with such an arrangement, when the object placing table 11 and the N image chains 12 rotate relative to each other by α degrees, the N image chains 12 can acquire and obtain the full scan data of the object to be scanned in the circumferential direction, and the full scan data of the object to be scanned in the present invention is formed by overlapping the N segmented scan data acquired by the N image chains 12.

Referring to fig. 3 in conjunction with fig. 1 and 2, each image chain 12 includes a set of source-detector groups 121 and collimators 122 corresponding to the source-detector groups 121. The source-detector group 121 includes a source 123 and a detector 124 respectively disposed at two opposite sides of the object placing table 11, and a relative position between the source 123 and the detector 124 in the same source-detector group 121 is unchanged. The radiation source 123 and the detector 124 are annularly disposed around the object placing table 11, the detector 124 is disposed inside the radiation source 123, and a gap 125 (as shown in fig. 1) for the radiation of the radiation source 123 to pass through is disposed between two adjacent detectors 124.

Further, N sets of radiation source-detector sets 121 in the N image chains 12 intersect at a position (i.e., an imaging field of view), and the object placing table 11 is disposed at the position, so that the radiation emitted by the N radiation sources 123 in the N sets of radiation source-detector sets 121 can pass through the object to be scanned, thereby completing data acquisition of the object to be scanned; preferably, 29 (N-29) image chains 12 are provided.

In a preferred embodiment of the present invention, the CT imaging system 100 has a guide rail 13 disposed around the object placing table 11, at this time, the object placing table 11 is fixed in position, and the image chain 12 can rotate around the object placing table 11 along the guide rail 13 to drive the radiation source-detector set 121 to scan the object to be scanned and obtain the segmented projection data/partial projection data of the object to be scanned. Of course, in other embodiments of the present invention, the placing table 11 may also be configured as a rotary placing table, and the image chain 12 is installed on the guide rail 13, at this time, both the placing table 11 and the image chain 12 can be rotated, so that the scanning time of the radiation source-detector set 121 can be further reduced, so as to achieve the purpose of increasing the time resolution of the CT imaging system 100, and thus the CT imaging system 100 is suitable for moving objects to be scanned, such as moving organs or tissues.

A collimator 122 is disposed between the radiation source 123 and the detector 124 for removing scattered radiation between the radiation source-detector set 121 and inside the radiation source-detector set 121. Specifically, the collimator 122 includes a first collimator 126 and a second collimator (not numbered), and the first collimator 126 is disposed at both sides of a radiation emitting path of the radiation source 123 for removing scattered radiation between the radiation source-detector group 121 and the radiation source-detector group 121. It should be noted that the first collimator 126 needs to consider the problem of shielding of the ray path in the radiation source 123 during the installation process, so as to prevent the ray shielding caused by the installation of the first collimator 126, and in a preferred embodiment of the present invention, the first collimator 126 is a two-dimensional mechanical collimator, and the length of the first collimator 126 is smaller than the mechanical aperture of the scanning apparatus 1 (as shown in fig. 3).

A second collimator is disposed adjacent to the detector 124 for removing scattered radiation within the source-detector set 121. Specifically, the second collimator is disposed substantially parallel to the detector 124, and the central axis of the first collimator 126 is substantially perpendicular to the plane of the second collimator and is aligned with the center of the second collimator, so that the interference of scattered rays inside the source-detector set 121 can be prevented while the amount of ray transmission of the source 123 is ensured.

It should be noted that N image chains 12 in the CT imaging system 100 may be simultaneously turned on, that is, the N radiation sources 123 emit radiation rays simultaneously, and the N detectors 124 acquire data simultaneously; alternatively, the source 123 may be turned on at intervals to emit radiation, and the N detectors 124 may acquire data simultaneously.

Specifically, when the radiation sources 124 in the N image chains 12 are turned on at intervals, the detector 124 corresponding to the radiation source 123 in operation may collect projection data of the object to be scanned, while the detector 124 corresponding to the radiation source 123 in the non-operation state may collect radiation scattering data of the radiation source 123, and the collected radiation scattering data may be used to correct a scattering signal in the projection data, so as to improve data accuracy of the projection data (including segmented projection data/partial projection data), and further improve image quality of a CT image acquired by the CT imaging system 100.

Referring to fig. 4, an imaging method for a CT imaging system 100 to acquire a CT image according to the present invention includes the following steps:

s2, fitting and reconstructing the image based on a series of segmented projection data to obtain a complete scanning image of the body to be scanned;

s4, fitting and reconstructing the image based on a series of partial projection data to obtain a partial scanning image of the body to be scanned;

and S5, correcting the full scanning image based on the partial scanning image to acquire a CT image of the body to be scanned.

Referring to fig. 5a and 5b in combination with fig. 1 to 4, step S1 specifically includes:

s11, opening the radiation sources 123 in the plurality of image chains 12 at intervals, and simultaneously opening all the detectors 124 in the plurality of image chains 12 to obtain radiation scattering data of the radiation sources 123;

s12, carrying out full scanning on the body to be scanned, and acquiring segmented projection data of the body to be scanned;

and S13, correcting the segmented projection data through the ray scattering data to acquire a series of segmented projection data with higher data precision.

In step S1, a series of segmented projection data is obtained by rotating several image chains 12 by β degrees with respect to the object to be scanned placed on the object placing table 11, where β ≧ α. With such an arrangement, when the plurality of image chains 12 operate simultaneously and rotate by α degrees, all data acquisition of the object to be scanned in the circumferential direction can be completed, and compared with the data acquisition mode of the conventional CT system, the imaging method of the present invention can effectively reduce the scanning time of the CT imaging system 100, so that the CT imaging system 100 has a higher time resolution.

In step S2, a full scan image is formed by angle-complementarily superimposing a series of segmented scan images after reconstructing the series of segmented projection data into the series of segmented scan images. The segmented projection data are simultaneously scanned and acquired by the N image chains 12, and the N segmented projection data scanned and acquired by the N image chains 12 can be superimposed to form complete scanning data of the object to be scanned in the circumferential direction. It should be noted that, in the present invention, the full scan image is formed by complementary overlapping of the segmented scan images, but in other embodiments, the full scan image may be formed by reconstructing from the full projection data after a series of segmented projection data are angularly and complementarily overlapped into the full projection data.

Step S3 specifically includes:

s31, opening the radiation sources 123 in the plurality of image chains 12 at intervals, and simultaneously opening all the detectors 124 in the plurality of image chains 12 to obtain radiation scattering data of the radiation sources 123;

s32, carrying out partial scanning on the body to be scanned, and acquiring partial projection data of the body to be scanned;

and S33, correcting the partial projection data through the ray scattering data to acquire a series of partial projection data with higher data precision.

In step S3, a series of partial projection data is obtained by rotating the image chains 12 by γ degrees with respect to the object to be scanned, and γ < α. Specifically, the number of the partial projection data and the number of the image chains 12 in the present invention are the same, that is, N, and since the partial projection data is short in acquisition time and has a plurality of acquisition positions and angles (see fig. 6 in combination with fig. 2), motion artifacts generated in the scanning process of the object to be scanned are effectively avoided, so that the partial scan image acquired by reconstructing the partial projection data can accurately represent the real information of the object to be scanned, and further, the full scan image corrected by the partial scan image can be used as a CT image to clearly display the real situation of the moving object to be scanned.

It should be noted that, the acquisition of the ray scattering data in step S1 and step S3 can effectively reduce data errors caused by scattered ray interference between the image chain 12 and the image chain 12, so that the segmented projection data acquired in step S1 and the partial projection data acquired in step S3 are more accurate, the accuracy of the complete scan image fitted and reconstructed in step S2 and the partial scan image fitted and reconstructed in step S4 is further improved, and the purpose of improving the image quality of the CT image acquired by the CT imaging system 100 is further achieved.

Further, the ray scattering data of the ray source 123 in step S11 and step S31 are obtained in the same manner, so in other embodiments of the present invention, the ray scattering data obtained in step S11 can be directly used to correct part of the projection data, so as to simplify the steps of the imaging method.

In steps S2 and S4, the full scan image and the partial scan image may be reconstructed by a neural network-based image reconstruction algorithm.

In summary, the CT imaging system 100 of the present invention sets a plurality of image chains 12 capable of simultaneously acquiring data of a to-be-scanned body, and enables the to-be-scanned body and the plurality of image chains 12 to rotate relatively to obtain a fully-scanned image and a partially-scanned image of the to-be-scanned body, respectively, so as to rapidly image a moving organ or tissue or a deformed object, and obtain a CT image with high image quality and time resolution, thereby increasing the imaging efficiency of the CT imaging system 100, overcoming the defect that a moving object or a deformed object has more motion artifacts during imaging, and enabling the imaging method and the CT imaging system 100 of the present invention to be applicable to CT imaging of a moving organ or tissue or a deformed object, and have high image quality and time resolution.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.

Claims

1. A CT imaging system for CT scan imaging of a volume to be scanned, comprising: including the ring locate treat a plurality of image chain of scanning body week side, treat the scanning body with but relative rotation between a plurality of image chain, the image chain include source-detector group and with the collimater that source-detector group one-to-one set up, the collimater sets up between source and detector to get rid of between source-detector group and the inside scattered ray of source-detector group.

2. The CT imaging system of claim 1, wherein: the image chains are arranged in number of N, the N image chains are arranged on a plane in a staggered mode at a fixed angle, the fixed angle between every two adjacent image chains is alpha, the alpha is 360 degrees/N, and N is larger than or equal to 2.

3. The CT imaging system of claim 1, wherein: the collimator comprises a first collimator and a second collimator, the first collimator is arranged at two sides of a ray emission path of the ray source and is used for removing scattered rays between the ray source-detector group and the ray source-detector group; the second collimator is arranged close to the detector and is used for removing scattered rays inside the ray source-detector set.

4. The CT imaging system of claim 3, wherein: the first collimator is a two-dimensional mechanical collimator.

5. The CT imaging system of claim 3, wherein: the second collimator is arranged approximately parallel to the detector, the central axis of the first collimator is approximately perpendicular to the plane of the second collimator, and the central axis of the first collimator and the center of the second collimator are located on the same straight line.

6. An imaging method for acquiring a CT image by using the CT imaging system of any one of claims 1-5, comprising the steps of:

7. The imaging method according to claim 6, characterized in that: in step S1, the series of segmented projection data is obtained by rotating the image chains by β degrees with respect to the object to be scanned, where β is greater than or equal to α.

8. The imaging method according to claim 6, characterized in that: in step S2, the full scan image is formed by angle-complementarily superimposing a series of segmented scan images after reconstructing the series of segmented projection data into a series of segmented scan images.

9. The imaging method according to claim 6, characterized in that: in step S3, the series of partial projection data is obtained by rotating the image chains by γ degrees with respect to the object to be scanned, and γ < α.

10. The imaging method according to claim 6, characterized in that: the steps S1 and S3 further include: and starting the ray sources arranged at intervals in the plurality of image chains, simultaneously starting all the detectors in the plurality of image chains to acquire ray scattering data of the ray sources, and correcting the segmented projection data in the step S1 and the partial projection data in the step S3 by using the ray scattering data.