Static real-time CT imaging system and imaging method

Abstract

The present invention discloses a static real-time CT imaging system and imaging method. The system includes two radiation source rings and a detector ring. The left and right radiation source rings are located on both the left and right sides of the detector ring in the Z-axis. The left and right radiation source rings are each ring-shaped multi-focal X-ray sources with multiple X-ray sources, with the same number of foci evenly distributed. The detector ring is composed of multiple X-ray detectors arranged in a ring shape. In the Z-axis, the multiple X-ray detectors together form a left detector sub-ring, a middle detector sub-ring, and a right detector sub-ring. In the left detector sub-ring, the X-ray source of the left radiation source ring is located between any two adjacent X-ray detectors. In the right detector sub-ring, the X-ray source of the right radiation source ring is located between any two adjacent X-ray detectors. In the middle detector sub-ring, any two adjacent X-ray detectors are in close contact with each other. By utilizing the present invention, wider Z-direction coverage can be achieved and cone angle artifacts can be effectively suppressed.

Description

[Technical Field]

[0001] The present invention relates to a static real-time CT imaging system and a corresponding static real-time CT imaging method, which belong to the technical field of medical imaging. [Background technology]

[0002] CT (Computed Tomography) is a term used to describe a type of computed tomography (CT) scanning technique. Its imaging principle is as follows: X-ray beams and highly sensitive X-ray detectors are used to scan the area around a specific part of the human body, layer by layer. The X-rays passing through the X-ray detector are received, converted into electrical signals by a photoelectric converter, amplified, and then converted into digital signals by an analog-to-digital converter, which are then input into a computer for processing. The computer then divides the selected layer into multiple cubes of equal volume called voxels. The information obtained from the layer-by-layer cross-sectional scan is calculated to obtain the X-ray attenuation or absorption coefficient for each voxel, which is then arranged in a matrix, known as a voxel digital matrix. The digital information in the voxel digital matrix is ​​converted into small squares of varying shades, ranging from black to white. These are called pixels in two-dimensional projections and arranged in a tomographic fashion to form a CT image.

[0003] To increase scanning speed, improve imaging accuracy and speed, avoid the effects of centrifugal force caused by mechanical rotation, and reduce the degree of signal drag and overlapping crosstalk during high-speed rotation, the applicant disclosed a static real-time CT imaging system in a Chinese patent bearing Patent No. ZL201410425061.2. This static real-time CT imaging system comprises a ring-shaped X-ray detector, a ring-shaped scanning X-ray source, and a scan timing controller. This static real-time CT imaging system eliminates the need for significant rotation of the ring-shaped scanning X-ray source during the scanning process, and instead electronically switches the X-ray projection position sequentially, thereby improving the scanning speed by several tens of times and enabling the production of dynamic 3D stereoscopic images. The X-ray detector can be used to obtain absorption data and energy data, thereby enabling real-time data reconstruction.

[0004] In addition, a Chinese patent with application number 201910865387.X discloses a static real-time CT imaging system and imaging control method with a pair of radiation source rings. This system places radiation sources on the left and right sides of the detector ring, respectively, and reconstructs the projection areas of the two radiation source rings separately to obtain two reconstructed fields of view (FOVs). However, there is a gap between the two FOVs. While helical scanning can compensate for the gap, single axial scanning cannot. Therefore, there are certain limitations to its application in expanding scan coverage. Summary of the Invention [Problem to be solved by the invention]

[0005] The main technical problem that this invention aims to solve is to provide a static real-time CT imaging system.

[0006] Another technical problem to be solved by the present invention is to provide a static real-time CT imaging method.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solutions.

[0008] According to a first aspect of an embodiment of the present invention, there is provided a static real-time CT imaging system comprising at least two radiation source rings and one detector ring, In this case, in the Z axis, the left radiation source ring and the right radiation source ring are installed on both the left and right sides of the detector ring, and the two radiation source rings share the detector ring; the left radiation source ring and the right radiation source ring are each a ring-shaped multi-focal X-ray source having a plurality of X-ray sources, the left radiation source ring and the right radiation source ring have the same number of foci uniformly arranged, the detector ring is composed of a plurality of X-ray detectors arranged in a ring shape, and in the Z axis, the plurality of X-ray detectors together form a left detector sub-ring, a middle detector sub-ring and a right detector sub-ring; In the left detector sub-ring, a first gap is formed between any two adjacent X-ray detectors for positioning the X-ray source of the left radiation source ring, and in the right detector sub-ring, a second gap is formed between any two adjacent X-ray detectors for positioning the X-ray source of the right radiation source ring, and in the intermediate detector sub-ring, any two adjacent X-ray detectors are in close contact with each other.

[0009] Preferably, the sizes of the multiple X-ray detectors are all the same, and the multiple X-ray detectors are arranged intertwined with each other to form the left detector sub-ring, the middle detector sub-ring and the right detector sub-ring, and the foci of the left radiation source ring and the right radiation source ring are arranged intertwined with each other.

[0010] Preferably, the X-ray detector comprises a short-sized X-ray detector and a long-sized X-ray detector, and a plurality of the short-sized X-ray detectors and a plurality of the long-sized X-ray detectors are sequentially arranged crosswise to form the left detector sub-ring, the middle detector sub-ring and the right detector sub-ring, and the left radiation source ring and the right radiation source ring are installed symmetrically on both the left and right sides of the detector ring.

[0011] Preferably, the X-ray detector comprises a main detector and a scatter detector disposed on one side or both sides of the main detector; A beam limiter is set between the X-ray source and the X-ray detector to limit the coverage of the radiation beam of the X-ray source so that it covers only the main detector.

[0012] Preferably, the beam limiter specifically comprises: a Z-direction beam limiting device movable open and closed on a Z-axis to limit the coverage of the radiation beam of the X-ray source in the Z-direction; an X-direction beam limiting device movable open and closed on an X-axis to limit coverage of the radiation beam of the X-ray source in the X-direction; The Z direction is the axial direction of the detector ring, and the X direction is the tangential direction of the detector ring.

[0013] Preferably, the Z-direction beam limiting device includes a Z-direction fixed unit and a Z-direction movable unit, the Z-direction fixed unit is fixedly installed along the Z-axis direction, and the Z-direction movable unit adjusts the size of an opening between the Z-direction fixed unit and the Z-direction movable unit by moving toward or away from the Z-direction fixed unit along the Z-axis direction; The X-direction beam limiting device includes two X-direction movable parts, and the two X-direction movable parts move closer to or farther away from each other along the X-axis direction to adjust the opening size between the two movable parts in the X direction.

[0014] Preferably, the plurality of X-ray sources in the left radiation source ring and the right radiation source ring are (1) The left radiation source is exposed, then the right radiation source is exposed, then the left radiation source is exposed, and so on. By analogy, all the radiation sources are exposed alternately from left to right, and projection images of all the radiation sources are obtained. (2) The K radiation sources on the left side are exposed simultaneously, and the X-ray detectors corresponding to the light field coverage of the K radiation sources on the left side are not shared; then the K radiation sources on the right side are exposed simultaneously, and the X-ray detectors corresponding to the light field coverage of the K radiation sources on the right side are not shared; etc. In this way, all the radiation sources are exposed alternately to the left and right sides, and projection images of all the radiation sources are obtained, where K is a positive integer greater than or equal to 2. (3) Rotate the exposure of the left radiation source and acquire only the projection image of the left radiation source. (4) The right radiation source is exposed in turn, and only the projection images of the right radiation source are acquired by axial scanning in one of the methods.

[0015] Preferably, the static real-time CT imaging system further includes a scan timing controller, and the exposure timing of the multiple foci in the left radiation source ring and the right radiation source ring and the collection timing of the corresponding X-ray detectors in the detector ring are controlled by the scan timing controller.

[0016] According to a second aspect of the present invention, there is provided a static real-time CT imaging method realized based on the static real-time CT imaging system, the method comprising at least: using a scan timing controller to control the X-ray sources in the left and right radiation source rings and the corresponding X-ray detectors in the detector ring to operate at a predetermined scan timing; The method includes a step in which the multiple X-ray sources in the left radiation source ring and the right radiation source ring emit X-rays according to a predetermined exposure timing, and the corresponding X-ray detectors collect projection information at the X-ray detectors after the X-rays pass through a measurement object.

[0017] Preferably, the projection information includes left-side local projection information collected by the left detector sub-ring, complete projection information collected by the middle detector sub-ring, and right-side local projection information collected by the right detector sub-ring. [Effects of the Invention]

[0018] Compared with the prior art, the present invention has the following technical features: 1. The dual-source ring structure expands the scanning coverage in the Z-axis direction, eliminating gaps between the left and right Z-axis coverages. This enables single-axis scanning to achieve wider Z-axis coverage, and further reduces the projection cone angle, effectively suppressing cone angle artifacts. 2. The multiple X-ray sources (i.e., multiple focal points) in the left and right radiation source rings can be used to achieve a single axial scan in various ways to meet different scanning requirements. Furthermore, the multiple focal points in the left and right radiation source rings can be used to scan the energy spectrum in various ways. 3. The X-ray detector is composed of a scatter detector and a main detector, and scatter correction can be realized by measuring the distribution of the scatter signal using the scatter detector. 4. The beam limiter can adapt to different FOV range requirements by adjusting the radiation coverage of the X-ray source. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing the three-dimensional structure of a static real-time CT imaging system provided by a first embodiment of the present invention. FIG. [Figure 2] 1 is a top view showing a local area of ​​a static real-time CT imaging system in a first embodiment of the present invention. FIG. [Figure 3] 1 is a schematic diagram showing a projection of a single radiation source ring structure in the prior art; [Figure 4]FIG. 2 is a schematic diagram showing a projection of a dual radiation source ring structure in a first embodiment of the present invention. [Figure 5] 10 is a diagram showing the projection relationship between the X-ray beam and the detector ring when the detector sub-ring is missing ZL in the Z-axis direction in the first embodiment of the present invention. FIG. [Figure 6] 10 is a diagram showing the projection relationship between the X-ray beam and the detector ring when the detector sub-ring is missing ZR in the Z-axis direction in the first embodiment of the present invention. FIG. [Figure 7] 10 is a diagram showing the projection relationship between the X-ray beam and the detector ring in a state where the detector sub-ring is not missing in the Z-axis direction in the first embodiment of the present invention. FIG. [Figure 8] FIG. 2 is a diagram showing the projection relationship between the X-ray beam and the detector ring in a state where the detector sub-ring is not missing in the X-axis direction in the first embodiment of the present invention. [Figure 9] 1 is a schematic diagram showing the projection relationship between the X-ray beam and the detector ring when the detector sub-ring is missing ZL or missing ZR in the X-axis direction in the first embodiment of the present invention. FIG. [Figure 10] FIG. 2 is a schematic diagram showing timing when a single X-ray source sequentially emits X-rays in the first embodiment of the present invention. [Figure 11] FIG. 2 is a schematic diagram showing timings when three X-ray sources synchronously emit X-rays in the first embodiment of the present invention. [Figure 12] FIG. 2 is a schematic diagram showing timing when six X-ray sources irradiate X-rays in synchronization in the first embodiment of the present invention. [Figure 13] 1 is a schematic diagram showing the structure of an X-ray detector in a first embodiment of the present invention. [Figure 14] 1 is a schematic diagram showing beam limitations of an X-ray source and an X-ray detector in a first embodiment of the present invention. [Figure 15] FIG. 2 is a schematic diagram showing a structure in which scattering detectors in a first embodiment of the present invention are arranged in the ZX plane using a sparse matrix. [Figure 16] 3 is a schematic diagram illustrating beam limitation of a beam limiting device in the Z direction in the first embodiment of the present invention; FIG. [Figure 17] 3 is a schematic diagram illustrating beam limitation of the beam limiting device in the X direction in the first embodiment of the present invention; FIG. [Figure 18] FIG. 10 is a top view showing a localization of a static real-time CT imaging system provided by a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The technical contents of the present invention will be described in detail and specifically below in combination with the accompanying drawings and specific embodiments. <First Example>

[0021] 1, the static real-time CT imaging system provided by the first embodiment of the present invention comprises at least two radiation source rings, a detector ring 3, and a scan timing controller. In the Z-axis direction, a left radiation source ring 1 and a right radiation source ring 2 are installed on both the left and right sides of the detector ring 3, and the two radiation source rings share one detector ring 3. Here, the left radiation source ring 1, the right radiation source ring 2, and the detector ring 3 are mounted on a rotating bracket via bearings 1a, and the three are positioned on the same axis, which is commonly known as the Z-axis in the CT field.

[0022] Specifically, in this embodiment, the left radiation source ring 1 and the right radiation source ring 2 are each a ring-shaped multi-focus X-ray source having multiple X-ray sources, and N focal points are arranged in each of the left radiation source ring 1 and the right radiation source ring 2. That is, the two radiation source rings share 2N focal points, and each focal point of the left radiation source ring 1 is designated as F Li , and each focus of the right radiation source ring 2 is F Ri where i∈[1, N] and there are N foci F Li and N foci F RiAs shown in FIG. 2, the detector ring 3 is composed of a plurality of X-ray detectors 31 arranged in a ring shape, and all of the X-ray detectors have the same size. The plurality of X-ray detectors 31 are arranged in a left detector sub-ring Z L , Intermediate detector sub-ring Z C and right detector sub-ring Z R Specifically, the left detector sub-ring Z L In the right detector sub-ring Z, a first gap 101 for arranging the X-ray source of the left radiation source ring 1 is formed between any two adjacent X-ray detectors. R In the right radiation source ring 2, a second gap 102 for arranging the X-ray source is formed between any two adjacent X-ray detectors. C In this case, any two adjacent X-ray detectors are in close contact with each other.

[0023] The exposure timing of the multiple focal points in the left radiation source ring 1 and the right radiation source ring 2 and the data collection timing corresponding to the X-ray detectors in the detector ring 3 are controlled by the same scan timing controller. The multiple X-ray sources in the left radiation source ring 1 and the right radiation source ring 2 emit X-rays according to predetermined exposure timing, and the X-ray detectors 31 corresponding to them in the detector ring 3 collect projection information at the X-ray detectors 31 after the X-rays pass through the measurement object. In this embodiment, the projection information includes the X-rays from the left detector sub-ring Z L The left local projection information collected based on the intermediate detector sub-ring Z C The complete projection information collected based on the right detector sub-ring Z R It can be seen that the right local projection information collected based on the double radiation source ring structure is included. This allows the scanning coverage in the Z-axis direction to be expanded, achieving gap-free coverage in both the left and right Z directions, and achieving wider Z-direction coverage with single-axis scanning. This further reduces the projection cone angle and effectively suppresses cone angle artifacts.

[0024] The differences between the single-source and dual-source structures are explained in detail below.

[0025] 3 is a schematic diagram showing a Z-direction projection of a single radiation source ring structure in the prior art. FIG. 4 is a schematic diagram showing a Z-direction projection of a dual radiation source ring structure in this embodiment. Here, F i is the focus of the single radiation source ring, and F Li and F Ri are the two foci in the Z direction in the dual radiation source ring structure of this embodiment, the dotted rectangular area is the image range that can be reconstructed in the Z direction corresponding to the two structures, and α1 and α2 correspond to the cone angles of the projection in the two modes, respectively. Referring to Figures 3 and 4, if the detector width in the Z direction does not change and the vertical distance between the foci and the detector does not change, α1 > α2, and the Z direction coverage in Figure 3 is less than the Z direction coverage in Figure 4. That is, in this embodiment, the Z direction coverage is larger and the cone angle of the radiation beam is smaller, thereby reducing the problem of cone angle artifacts in image reconstruction.

[0026] In addition, in this embodiment, the double radiation source ring structure expands the scanning coverage in the Z-axis direction, and referring to Figure 4, it can be seen that the reconstructable image range in the Z direction is larger to ensure the clinical application requirements for the Z-direction coverage of the CT device.

[0027] 5 to 7, in the Z-axis direction, the X-ray beam is incident on the Z axis of the detector ring. L , Z C and Z R Specifically, the Z L If a region lacks a photosensitive element, the X-ray beam will be reflected by the Z axis of the X-ray detector. C and Z R The projection relationship is formed as shown in Figure 5. Similarly, the Z R If a region lacks a photosensitive element, the X-ray beam will be reflected by the Z axis of the X-ray detector. C and Z L The projection relationship shown in Figure 6 is formed when the X-ray detector is fully Z-axis. L, Z C and Z R When the area has a photosensitive element, the radiation beam and the X-ray detector form a projection relationship as shown in FIG.

[0028] As shown in Figures 8 and 9, in the X-axis direction, the X-ray beam is directed along the Z axis of the detector ring. L , Z C and Z R and form two possible correspondences, where the X-axis direction is the tangential direction of the detector ring 3. Specifically, as shown in Figure 8, in the X-ray projection, the diagonal line section from the upper left to the lower right shows the actual X-ray projection geometry, and the detector Z C The geometric relationship of the projections corresponding to the regions is a projection covering the entire FOV. As shown in Figure 9, the Z L Area and Z R The area under the projection of the radiation source is the Z region of the detector ring due to the partial absence of the photosensitive elements of the detector. L Area and Z R The projection of the region is missing in the X-axis direction (i.e., the tangential direction). In this example, this partial missing projection can be resolved by a sparse sampling reconstruction algorithm, thereby achieving completeness of the reconstructed image in the X-direction FOV.

[0029] In the above embodiment, the X-ray sources (i.e., multiple focal points) in the left radiation source ring 1 and the right radiation source ring 2 can realize one axial scan in various ways, including at least the following four axial scan methods: (1) The left radiation source is exposed, then the right radiation source is exposed, then the left radiation source is exposed, and so on. In this manner, all the radiation sources are exposed alternately from left to right, and projection images of all the radiation sources are obtained. (2) A set of K radiation sources on the left side is exposed simultaneously, and the X-ray detectors 31 corresponding to the light field coverage of the K radiation sources on the left side are not shared, then a set of K radiation sources on the right side is exposed simultaneously, and the X-ray detectors 31 corresponding to the light field coverage of the K radiation sources on the right side are not shared, then another set of radiation sources on the left side is exposed simultaneously, ... In this way, all the radiation sources are exposed alternately from left to right, and projection images of all the radiation sources are obtained, where K is a positive integer greater than or equal to 2. (3) The left radiation source is exposed in turn, and only the projection image of the left radiation source is acquired. (4) The right radiation source is exposed in turn, and only the projection image of the right radiation source is acquired.

[0030] In addition, in the axial scanning methods (1), (2), (3), and (4), the exposure timing of one or more focal points in different regions of the single radiation source ring can be simultaneous or time-shared, point-by-point or point-interlaced, or row-by-row or interlaced. Each X-ray source in the left radiation source ring 1 and the right radiation source ring 2 can emit X-rays sequentially along the circumferential direction, or multiple X-ray sources can emit X-rays sequentially with intervals between them. The X-ray sources in the left radiation source ring 1 and the right radiation source ring 2 can emit X-rays only from a single X-ray source (see FIG. 10), or multiple X-ray sources can simultaneously emit X-rays in parallel (see FIGS. 11 and 12). The maximum number of X-ray sources emitting X-rays in parallel is determined based on the assumption that the parallel-emitted X-rays do not interfere with each other at the X-ray detector 31. It is preferable that the circumferential distribution of the X-ray sources emitting X-rays in parallel is uniform.

[0031] X-rays emitted from the X-ray sources in the left radiation source ring 1 and the right radiation source ring 2 pass through the object to be measured and then hit the corresponding X-ray detectors 31 in the detector ring 3. The data collection and processing unit is composed of multiple distributed subsystems, each with an integrated GPU. The X-ray projection information received by the X-ray detector 31 is collected by the data collection and processing unit, which then performs image reconstruction processing. The reconstructed image information is transmitted to the image data storage unit and the human-computer interaction unit, which then completes image storage and visual reproduction. Of course, existing CT data collection and processing methods can also be used. The data collection and processing unit only collects data, and then sends the data to the image reconstruction unit and the data storage unit for reconstruction and storage.

[0032] This static real-time CT imaging system can achieve energy spectrum scanning in various ways by using multiple focal points in the left and right radiation source rings. First, the left and right radiation source rings can perform energy spectrum scanning using instantaneous energy level switching of a single X-ray source, allowing for instantaneous switching between multiple energy levels (e.g., switching between 80 kV, 100 kV, 120 kV, and 140 kV). The specific number of energy levels to be switched is determined by design requirements. After one X-ray source performs energy spectrum scanning via instantaneous energy level switching, the next X-ray source under scan timing control also performs energy spectrum scanning in the same manner until the entire scanning operation is completed. Second, the left and right radiation source rings can perform energy spectrum scanning using intermittent energy level switching in the circumferential direction. That is, each X-ray source in the left radiation source ring 1 and the right radiation source ring 2 completes a circumferential scan at the same energy level under timing control, then switches to a different energy level, and the next circumferential scan is repeated until all energy level switching is complete. Alternatively, the left radiation source ring 1 and the right radiation source ring 2 can perform energy spectrum scanning using a circumferential multi-energy spectrum scanning method. That is, the circumferentially distributed scanning X-ray sources are divided into multiple groups, and each group is integrated into one energy level. After completing a circumferential scan under timing control, the energy level of each group of scanning X-ray sources is switched to the corresponding next energy level, and the next circumferential scan is repeated until all energy level switching is complete. Finally, the left radiation source ring 1 and the right radiation source ring 2 can simultaneously use two different energy levels. Specifically, one energy level (A kV) is used at multiple foci in the left radiation source ring 1, and another energy level (B kV, B ≠ A) is used at multiple foci in the right radiation source ring 2, resulting in energy-spectral images of two energy levels in a single scan.

[0033] It should be noted that the X-ray detector 31 in this embodiment may be a photon flow detector, and the same function can be realized by switching to an energy integrating detector.

[0034] Referring to FIG. 13 , in the above embodiment, the X-ray detector 31 preferably includes a main detector 311 and a scatter detector 312, with the scatter detector 312 located on one or both sides of the main detector 311. Also, as shown in FIG. 14 , in this embodiment, a beam limiter 10 is installed between the X-ray source and the X-ray detector 31 to limit the coverage of the main radiation beam at the X-ray source so that it only covers the main detector 311. As a result, the scatter detector 312 is not covered by the main radiation beam, and the signal measured thereby is the X-ray scattering distribution generated by the interaction of the main radiation beam with the scanned object. In this way, while acquiring a projection image, the scatter distribution information is acquired to form a scatter matrix, which is then integrated with the projection matrix acquired by the main detector and uploaded to the data acquisition server in the form of a data flow. The data acquisition server then separates the scatter information from the image information, restores the complete scatter information, and removes it from the image information to achieve scatter correction.

[0035] In the above embodiments, it can be understood that the scatter detector 312 and the main detector 311 can be in various situations regardless of specific implementation forms. For example, it may be an independent PD array, or an array of photosensitive elements of various detectors (including, but not limited to, CMOS + PD, TFT + PD, indirect X-ray detectors, direct X-ray detectors (such as amorphous selenium, cadmium telluride (CdTe), cadmium zinc telluride (CdZnTe, CZT), cadmium selenide (CdSe), IGZO, etc.)). In this embodiment, when the pixels of the main detector 311 are uniformly arranged, the pixel matrix of the main detector 311 can be represented as I(R*M), that is, R rows and M columns, and the pixel matrix of the scatter detector 312 can be represented as S(r*m), that is, r rows and m columns. When m = M, the number of columns of the main detector and the scatter detector is the same. When m < M, the arrangement of the scatter detector 312 in the Z-X plane can be in a sparse arrangement form (as shown in FIG. 15). By combining the sparse arrangement of the scatter detector 312 with the low-frequency characteristics of the scatter signal, scatter estimation based on scatter measurement is performed in the X direction and the Z direction, and it is removed from the image information. This method includes steps S10 to S30.

[0036] S10: Measurement and complement of scatter signal in the X direction Within a single X-ray detector 31, in the X direction, by complementing the scatter signal by interpolation, the same number of columns of the scatter matrix as the columns of the main detector can be obtained, and the scatter signal of S(r*m) is corrected to S(r * M). Between X-ray detectors 31, in the X direction, D Li and D Ri are offset in the Z direction, so the scatter amount between D Li can be complemented by interpolating the scatter amount of D Ri . Similarly, the scatter amount between D Ri can be complemented by interpolating the scatter amount of D Li .

[0037] S20: Measurement and complement of scatter signal in the Z direction In the Z direction, the number of rows r of the scatter detectors arranged on both sides must be three or more, and the scatter detectors must avoid the penumbra of the main radiation. The scatter signal matrix S(R*M) is obtained by fitting all the scatter signals in the image row in the Z direction with the distribution trend of the scatter signals on both sides.

[0038] S30: Removal of scattered signals The scatter information is removed by subtracting the image matrix I(R*M) from the extracted scatter signal S(R*M).

[0039] 16 and 17 , in the above embodiment, the beam limiter 10 includes a Z-direction beam limiting device 110 and an X-direction beam limiting device 120. Here, the Z-direction beam limiting device 110 is movable to open and close in the Z direction to limit the radiation coverage of the X-ray source in the Z direction, and the X-direction beam limiting device 120 is movable to open and close in the X direction to limit the radiation coverage of the X-ray source in the X direction. Specifically, in this embodiment, as shown in FIG. 16 , the Z-direction beam limiting device 110 includes a Z-direction fixed part 111 and a Z-direction movable part 112. The Z-direction fixed part 111 is fixedly installed along the Z-axis direction, and the Z-direction movable part 112 is installed to move toward or away from the Z-direction fixed part 111 along the Z-axis direction to adjust the size of the opening between the Z-direction fixed part 111 and the Z-direction movable part 112. 17, the X-direction beam limiting device 120 includes two X-direction movable parts 121 that are installed close to or far from each other along the X-axis direction and adjust the aperture size between the two X-direction movable parts 121 in the X direction. It can be understood that the larger the aperture, the larger the coverage (i.e., FOV range) of the radiation beam of the X-ray source, and the smaller the aperture, the smaller the coverage (i.e., FOV range) of the radiation beam of the X-ray source, which can be appropriately adjusted based on actual clinical requirements.

[0040] To summarize the above, the static real-time CT imaging system provided by the first embodiment of the present invention has the following beneficial effects: 1. The scanning coverage in the Z-axis direction has been expanded, achieving gap-free coverage in both the left and right Z directions. A single axial scan can achieve wider Z-direction coverage, and the projection cone angle can be further reduced, effectively suppressing cone angle artifacts. 2. The X-ray sources (i.e., multiple foci) in the left radiation source ring 1 and the right radiation source ring 2 can realize one axial scan in various ways to meet different scanning requirements. In addition, the multiple foci in the left radiation source ring 1 and the right radiation source ring 2 can realize energy spectrum scanning in various ways. 3. The X-ray detector 31 is composed of a scatter detector 312 and a main detector 311, which allows scatter correction to be performed using the scatter detector 312. 4. The beam limiter 10 can adjust the radiation coverage of the X-ray source to accommodate different FOV range requirements. <Second Example>

[0041] 18, the static real-time CT imaging system provided by the second embodiment of the present invention includes two radiation source rings, a detector ring 3, and a scan timing controller. Compared with the first embodiment, the difference of this embodiment is that the radiation source rings and the detector ring 3 are arranged in a different manner.

[0042] Specifically, in this embodiment, the plurality of X-ray detectors includes a plurality of short-sized X-ray detectors 31a and a plurality of long-sized X-ray detectors 31b, which are arranged in a cross-shaped pattern to form a left detector sub-ring, a middle detector sub-ring, and a right detector sub-ring. Furthermore, the left radiation source ring 1 and the right radiation source ring 2 are symmetrically installed on both the left and right sides of the detector ring 3.

[0043] In this embodiment, when exposing and scanning with X-rays, the short-sized X-ray detector 31a can measure only the projection of the area where the middle detector sub-ring is located, while the long-sized X-ray detector 31b can measure the projection of the entire area of ​​the left detector sub-ring, middle detector sub-ring, and right detector sub-ring. That is, the area where the long-sized X-ray detector 31b is located is expanded in the Z direction, which contributes to improving imaging quality.

[0044] Furthermore, compared to the first embodiment, in this embodiment, the X-ray source occupies a position. Therefore, as the number of focal points N of the X-ray source increases, the corresponding arc spacing between the focal points decreases, thereby gradually reducing the area in which the long-sized X-ray detector 31b is located. When the area in which the long-sized X-ray detector 31b is located disappears, the Z-direction expansion function is lost. Therefore, the number of focal points N of the X-ray source must be appropriately set as needed. Furthermore, while the arrangement method in the first embodiment can achieve a complementary effect in the projection view, the projection view in this embodiment does not have this complementary effect. Although the imaging effect of this embodiment is slightly inferior to that of the first embodiment, Z-direction expansion can still be achieved, and the imaging effect is superior to that of the prior art CT imaging system without Z-direction expansion.

[0045] Except for the above structure, the remaining structure of this embodiment is the same as that of the first embodiment, and therefore a description thereof will be omitted here. <Third Example>

[0046] A third embodiment of the present invention provides a static real-time CT imaging method implemented based on the static real-time CT imaging system in the first or second embodiment, which includes at least steps S1 and S2. S1: Using the scan timing controller, the X-ray sources in the left and right radiation source rings and the corresponding X-ray detectors in the detector ring are controlled to operate at a predetermined scan timing. S2: The multiple X-ray sources in the left radiation source ring and the right radiation source ring irradiate X-rays according to a predetermined exposure timing, and the corresponding X-ray detectors collect projection information on the X-ray detectors after the X-rays pass through the measurement object.

[0047] It can be understood that the projection information in this embodiment includes left-side local projection information collected by the left detector sub-ring, complete projection information collected by the middle detector sub-ring, and right-side local projection information collected by the right detector sub-ring.

[0048] The static real-time CT imaging system and imaging method provided by the present invention have been described in detail above. Any obvious modifications made to the present invention without departing from the essential content of the present invention by those skilled in the art will constitute infringement of the patent right of the present invention and will incur corresponding legal liability.

Claims

1. 1. A static real-time CT imaging system comprising: at least two radiation source rings and one detector ring; In the Z-axis, the left radiation source ring and the right radiation source ring are installed on both the left and right sides of the detector ring, and the two radiation source rings share the detector ring; the left radiation source ring and the right radiation source ring are each a ring-shaped multi-focal X-ray source having a plurality of X-ray sources, the left radiation source ring and the right radiation source ring have the same number of foci uniformly arranged, the detector ring is composed of a plurality of X-ray detectors arranged in a ring shape, and the plurality of X-ray detectors together form a left detector sub-ring, a middle detector sub-ring and a right detector sub-ring in the Z axis; A static real-time CT imaging system, characterized in that in the left detector sub-ring, a first gap is formed between any two adjacent X-ray detectors for positioning an X-ray source of the left radiation source ring, and in the right detector sub-ring, a second gap is formed between any two adjacent X-ray detectors for positioning an X-ray source of the right radiation source ring, and in the intermediate detector sub-ring, any two adjacent X-ray detectors are in close contact with each other.

2. The X-ray detectors are all the same size, the plurality of X-ray detectors are arranged intertwined with one another to form the left detector sub-ring, the middle detector sub-ring, and the right detector sub-ring; 2. The static real-time CT imaging system of claim 1, wherein the focal points of the left and right radiation source rings are arranged in a staggered relationship.

3. 2. The static real-time CT imaging system of claim 1, wherein the X-ray detector comprises a short-sized X-ray detector and a long-sized X-ray detector, and the plurality of short-sized X-ray detectors and the plurality of long-sized X-ray detectors are sequentially arranged crosswise to form the left detector sub-ring, the middle detector sub-ring and the right detector sub-ring, and the left radiation source ring and the right radiation source ring are installed symmetrically on both the left and right sides of the detector ring.

4. the X-ray detector comprises a main detector and a scatter detector disposed on one or both sides of the main detector; 2. The static real-time CT imaging system according to claim 1, wherein a beam limiter is set between the X-ray source and the X-ray detector to limit coverage so that the radiation beam of the X-ray source covers only the main detector.

5. The beam limiter comprises: a Z-direction beam limiting device movable open and closed on a Z-axis to limit the coverage of the radiation beam of the X-ray source in the Z-direction; an X-direction beam limiting device movable open and closed on an X-axis to limit coverage of a radiation beam of the X-ray source in the X-direction; 5. The static real-time CT imaging system of claim 4, wherein the Z direction is an axial direction of the detector ring, and the X direction is a tangential direction of the detector ring.

6. the Z-direction beam limiting device includes a Z-direction fixed unit and a Z-direction movable unit, the Z-direction fixed unit is fixedly installed along the Z-axis direction, and the Z-direction movable unit adjusts an opening size between the Z-direction fixed unit and the Z-direction movable unit by moving toward or away from the Z-direction fixed unit along the Z-axis direction; 6. The static real-time CT imaging system of claim 5, wherein the X-direction beam limiting device comprises two X-direction movable parts, and the two X-direction movable parts adjust the opening size between the two movable parts in the X direction by moving closer to or farther away from each other along the X-axis direction.

7. The plurality of X-ray sources in the left radiation source ring and the right radiation source ring include: (1) The left radiation source is exposed, then the right radiation source is exposed, and then the left radiation source is exposed, thereby exposing all the radiation sources alternately from left to right and acquiring projection images of all the radiation sources; (2) simultaneously expose the K radiation sources on the left side, without sharing the X-ray detectors corresponding to the light field coverage of the K radiation sources on the left side; then simultaneously expose the K radiation sources on the right side, without sharing the X-ray detectors corresponding to the light field coverage of the K radiation sources on the right side; and alternately expose all the radiation sources on the left and right sides to obtain projection images of all the radiation sources, where K is a positive integer greater than or equal to 2; (3) Rotate the exposure of the left radiation source and obtain only the projection image of the left radiation source; (4) The static real-time CT imaging system of claim 1, characterized in that axial scanning is performed using any one of the following methods: exposing the right-side radiation source alternately and acquiring only the projection view of the right-side radiation source.

8. 2. The static real-time CT imaging system of claim 1, further comprising a scan timing controller, wherein exposure timings of multiple focal points in the left and right radiation source rings and collection timings of corresponding X-ray detectors in the detector ring are controlled by the scan timing controller.

9. A static real-time CT imaging method implemented on the basis of the static real-time CT imaging system according to any one of claims 1 to 8, comprising: using a scan timing controller to control the X-ray sources in the left and right radiation source rings and the corresponding X-ray detectors in the detector ring to operate at a predetermined scan timing; a step of: a plurality of X-ray sources in the left radiation source ring and the right radiation source ring emitting X-rays according to a predetermined exposure timing; and a step of collecting projection information at the corresponding X-ray detectors after the X-rays have passed through a measurement object.

10. 10. The static real-time CT imaging method of claim 9, wherein the projection information includes left-side local projection information collected by the left detector sub-ring, complete projection information collected by the middle detector sub-ring, and right-side local projection information collected by the right detector sub-ring.

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