Scattering estimation method, imaging system, correction device and storage medium

Abstract

Embodiments of the present application provide a scattering estimation method, an imaging system, a correction device and a storage medium, and relate to the technical field of medical imaging. After a projection image formed by an imaging beam passing through a blocking array plate is acquired, scattering sampling points corresponding to each blocking column in the blocking array plate in the projection image are acquired, interpolation is performed on the empty space between each two adjacent scattering sampling points according to the scattering signals of the two scattering sampling points, interpolation sampling points are obtained, and then a scattering distribution diagram corresponding to the projection image is obtained according to the scattering signals of each scattering sampling point and each interpolation sampling point. In this way, the imaging beam is shielded by the blocking array plate, interpolation is performed on the empty space between each two adjacent scattering sampling points, and then the scattering distribution of the projection image can be effectively estimated according to the scattering signals of each scattering sampling point and each interpolation sampling point, thereby improving the accuracy of the scattering estimation of the projection image.

Description

Technical Field

[0001] This invention relates to the field of medical imaging technology, and more specifically, to a scattering estimation method, an imaging system, a correction device, and a storage medium. Background Technology

[0002] The application of computed tomography (CT) technology in clinical medicine is one of the important hallmarks of medical technological progress in the 20th century. With the development of science and technology, CT scanning methods have undergone tremendous changes, and cone-beam CT has entered the practical application stage.

[0003] Cone-beam CT (CBCT) is a computed tomography imaging system that uses a cone-beam imaging source, such as an X-ray tube, to digitally project a low dose of radiation around the subject in a circular pattern. The data obtained from multiple digital projections around the subject are then reconstructed to produce a three-dimensional reconstructed image. During cone-beam CT imaging, the scattering of X-ray photons affects the quality of the reconstructed image, such as decreased contrast and inaccurate CT values. Currently, the accuracy of photon scattering estimation during cone-beam CT imaging needs further improvement. Summary of the Invention

[0004] Based on the above research, the present invention provides a scattering estimation method, an imaging system, a correction device, and a storage medium, which can improve the accuracy of scattering estimation.

[0005] Embodiments of the present invention can be implemented in the following ways:

[0006] In a first aspect, embodiments of the present invention provide a scattering estimation method, the method comprising:

[0007] Acquire a projected image formed by the imaging beam passing through a blocking array plate, wherein the blocking array plate includes multiple blocking columns;

[0008] Obtain the scattering sampling points in the projected image corresponding to each of the blocking pillars;

[0009] Based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points;

[0010] Based on the scattering signals of each of the scattering sampling points and each of the interpolation sampling points, a scattering distribution map corresponding to the projected image is obtained.

[0011] In an optional implementation, the projected image includes a first projected image and a second projected image; the first projected image is a projected image formed without the object to be tested placed thereon, and the second projected image is a projected image formed with the object to be tested placed thereon.

[0012] The step of obtaining the scattering sampling points corresponding to each of the blocking pillars in the projected image includes:

[0013] Obtain the center point of the shadow area in the first projected image that is blocked by each of the blocking pillars;

[0014] Based on the center point of each of the shadow regions, a target point corresponding to the center point of each of the shadow regions is obtained in the second projection image, and the target point is set as a scattering sampling point in the second projection image.

[0015] In an optional implementation, the step of obtaining the center point of the shadow area in the first projected image that is blocked by each of the blocking pillars includes:

[0016] The pixels in the first projected image are analyzed and processed to determine the shadow pixels corresponding to the shadow areas blocked by each of the blocking pillars;

[0017] Based on the shadow pixels, determine the center point of the shadow area in the first projected image that is blocked by each of the blocking pillars.

[0018] In an optional implementation, the step of interpolating the scattering signals of every two adjacent scattering sampling points into the gaps between them to obtain interpolated sampling points includes:

[0019] Acquire the scattering signal of each scattering sampling point within a set pixel range;

[0020] Based on the scattering signals of every two adjacent scattering sampling points within a set pixel range, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points.

[0021] In an optional implementation, the step of obtaining the scattering distribution map corresponding to the projected image based on the scattering signals of each of the scattering sampling points and each of the interpolation sampling points includes:

[0022] Based on the scattering signals of each scattering sampling point within a set pixel range and the scattering signals of each interpolation sampling point, interpolation or fitting is performed between each scattering sampling point and the interpolation sampling point to obtain a scattering distribution map.

[0023] In an optional implementation, after obtaining the scattering distribution map corresponding to the projected image, the method further includes:

[0024] Based on the scattering distribution map, the projected image is corrected to obtain the ray distribution map.

[0025] In an optional implementation, the step of correcting the projected image based on the scattering distribution map to obtain the ray distribution map includes:

[0026] Determine the ray signal of the target projection area in the projected image that is not blocked by the blocking pillars;

[0027] Determine the scattering signal of the target scattering region corresponding to the target projection region in the scattering distribution map;

[0028] Based on the scattering signal of the target scattering region, the ray signal of the target projection region is corrected to obtain a ray distribution map.

[0029] In an optional implementation, the step of correcting the ray signal of the target projection area based on the scattering signal of the target scattering area to obtain a ray distribution map includes:

[0030] The difference between the ray signal of the target projection area and the scattering signal of the target scattering area is calculated to obtain an initial ray distribution map;

[0031] Based on the location of each of the aforementioned scattering sampling points, the ray points to be interpolated in the initial ray distribution map are determined;

[0032] Based on the ray signals in the initial ray distribution map, the ray points to be interpolated are interpolated to obtain the ray distribution map.

[0033] In an optional implementation, after obtaining the scattering distribution map corresponding to the projected image, the method further includes:

[0034] Based on the positions of each of the scattering sampling points, the ray points to be interpolated in the projected image are determined;

[0035] Based on the ray signals in the projected image, the ray points to be interpolated are interpolated to obtain the interpolated projected image.

[0036] Based on the scattering distribution map, the interpolated projection image is corrected to obtain the ray distribution map.

[0037] In an optional implementation, after correcting the projected image to obtain the ray distribution map, the method further includes:

[0038] Based on the ray distribution map and the projection image, an attenuation integral image is calculated, and image reconstruction is performed based on the attenuation integral image.

[0039] In an optional implementation, after obtaining the scattering distribution map corresponding to the projected image, the method further includes:

[0040] Based on the scattering distribution map, the projected image is corrected to obtain a corrected image. Based on the corrected image and the projected image, the attenuation integral image is calculated.

[0041] Based on the positions of each of the scattering sampling points, the ray points to be interpolated in the attenuation integral image are determined;

[0042] Based on the ray attenuation signal in the attenuation integral image, the ray points to be interpolated are interpolated to obtain the interpolated attenuation integral image.

[0043] Image reconstruction is performed based on the interpolated attenuation integral image.

[0044] In a second aspect, embodiments of the present invention provide an imaging system, the imaging system comprising:

[0045] frame;

[0046] The imaging source is mounted on the frame;

[0047] An imager is mounted on the frame opposite to the imaging source;

[0048] A blocking array plate is disposed between the imaging source and the imager, and the blocking array plate includes a plurality of blocking columns;

[0049] A calibration device, connected to the imager, is used for:

[0050] A projection image is obtained by the imaging beam passing through a blocking array plate, the blocking array plate including multiple blocking columns; scattering sampling points corresponding to each blocking column in the projection image are obtained; based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points; based on the scattering sampling points and the scattering signals of each interpolated sampling point, a scattering distribution map corresponding to the projection image is obtained.

[0051] In an optional embodiment, the blocking array plate is provided with multiple rows of columns along a first direction, each row of columns including multiple blocking columns arranged along a second direction, wherein the blocking columns in adjacent rows of columns are staggered from each other, and the first direction and the second direction intersect.

[0052] In an optional embodiment, the intersection of the central axes of each of the blocking pillars coincides with the imaging focal point of the imaging source.

[0053] In an optional implementation, the imaging system further includes:

[0054] An array board driving device is mounted on the frame and connected to both the blocking array board and the correction device.

[0055] The array board driving device is used to drive the blocking array board to rotate under the control of the correction device.

[0056] Thirdly, embodiments of the present invention provide a correction device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the scattering estimation method described in any of the foregoing embodiments.

[0057] Fourthly, embodiments of the present invention provide a storage medium including a computer program, wherein the computer program, when running, controls the correction device where the storage medium is located to execute the scattering estimation method described in any of the foregoing embodiments.

[0058] The scattering estimation method, imaging system, correction device, and storage medium provided in this invention, after acquiring the projected image formed by the imaging beam passing through a blocking array plate, obtain scattering sampling points in the projected image corresponding to each blocking column in the blocking array plate. Based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points. Then, based on the scattering signals of each scattering sampling point and each interpolated sampling point, a scattering distribution map corresponding to the projected image is obtained. Thus, by setting a blocking array plate to block the imaging beam, interpolating in the gaps between every two adjacent scattering sampling points, and then based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be effectively estimated, improving the accuracy of scattering estimation of the projected image. Attached Figure Description

[0059] The technical solution and other beneficial effects of the present invention will become apparent from the following detailed description of specific embodiments of the invention, in conjunction with the accompanying drawings.

[0060] Figure 1 This is a schematic diagram of an imaging system provided in an embodiment of the present invention.

[0061] Figure 2 This is a schematic diagram of an application scenario of the imaging system provided in an embodiment of the present invention.

[0062] Figure 3 This is a schematic diagram of an interpolation method provided in an embodiment of the present invention.

[0063] Figure 4 This is a schematic diagram of a blocking array plate provided in an embodiment of the present invention.

[0064] Figure 5 This is a schematic diagram of a rotating blocking array plate provided in an embodiment of the present invention.

[0065] Figure 6 This is a rotating comparison diagram of a blocking array plate provided in an embodiment of the present invention.

[0066] Figure 7 This is a schematic diagram of another structure of the blocking array plate provided in an embodiment of the present invention.

[0067] Figure 8 This is a schematic diagram of a calibration device provided in an embodiment of the present invention.

[0068] Figure 9 This is a schematic flowchart of a scattering estimation method provided in an embodiment of the present invention.

[0069] Figure 10 This is a schematic diagram of a projected image provided in an embodiment of the present invention.

[0070] Figure 11 This is a grid sampling diagram provided in an embodiment of the present invention.

[0071] Figure 12 This is another interpolation diagram provided in an embodiment of the present invention.

[0072] Figure 13 This is another schematic diagram of the scattering estimation method provided in an embodiment of the present invention.

[0073] Figure 14 This is another flowchart illustrating the scattering estimation method provided in an embodiment of the present invention.

[0074] Icons: 100-Calibration device; 20-Memory; 30-Processor; 40-Communication unit; 200-Imaging source; 300-Blocking array plate; 400-Imager. Detailed Implementation

[0075] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0077] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0078] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0079] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0080] As described in the background section, the scattering of X-ray photons during cone-beam CT imaging affects the quality of reconstructed images, such as decreased contrast and inaccurate CT values. Currently, the accuracy of photon scattering estimation during cone-beam CT imaging needs further improvement.

[0081] Based on the above research, embodiments of the present invention provide a scattering estimation method, an imaging system, a correction device, and a storage medium. By setting a blocking array plate to obstruct the imaging beam, after acquiring the projected image formed by the imaging beam passing through the blocking array plate, scattering sampling points corresponding to each blocking column in the blocking array plate are determined in the projected image. Then, based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between each two adjacent scattering sampling points to obtain interpolated sampling points. Based on the scattering signals of each scattering sampling point and each interpolated sampling point, a scattering distribution map corresponding to the projected image is obtained. Thus, by setting a blocking array plate to obstruct the imaging beam, interpolating in the gaps between each two adjacent scattering sampling points, and then using the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be effectively estimated, improving the accuracy of scattering estimation of the projected image.

[0082] Please see Figure 1 , Figure 1 This is a schematic diagram of the imaging system provided in this embodiment. Figure 1 As shown, the imaging system provided in this embodiment includes an imaging source 200, a blocking array plate 300, an imager 400, a correction device 100, and a frame (not shown in the figure). The frame is the main structure of the imaging system, used to support other components. In this embodiment, the imaging source 200 and the imager 400 are arranged opposite each other on the frame.

[0083] In this embodiment, the imaging source 200 can be, but is not limited to, X-ray sources, gamma-ray sources, or other radiation sources. In this embodiment, the imaging source 200 can generate an imaging beam, which can be used to scan the object under test. The object under test can be a human body, a phantom, an animal, or any other object that can be imaged by the imaging system.

[0084] In this embodiment, the imager 400 can be a detector used to receive the rays emitted by the imaging source 200, convert the received rays into visible light, convert them into electrical signals through photoelectric conversion, and then convert them into digital signals through an analog-to-digital converter, thereby obtaining the projected image data.

[0085] In practice, the imaging source 200 generates rays to scan the object under test. The imager then receives the rays passing through the object and converts them into visible light. This visible light is then converted into an electrical signal via photoelectric conversion, and finally into a digital signal via an analog-to-digital converter, thus obtaining the projected image data of the object under test. After obtaining the projected image data, an image can be reconstructed based on this data.

[0086] However, when the imaging source 200 scans the object under test, the rays will scatter on the object, affecting the quality of the reconstructed image. To reduce the impact of scattering on the quality of the reconstructed image, a blocking array plate 300 is placed between the imager 400 and the imaging source 200. The blocking array plate 300 can be placed between the imaging source 200 and the object under test, or between the object under test and the imager 400, such as... Figure 2 As shown, specifically, it can be set according to actual needs.

[0087] In this embodiment, the blocking array plate 300 is parallel to the irradiation surface of the imaging source 200, and multiple blocking columns are provided on the blocking array plate 300. The position of each blocking column can be arbitrarily set, that is, the setting position of each blocking column is not limited, as long as there are gaps between each blocking column.

[0088] In this embodiment, each blocking pillar can be formed of a high-attenuation material (such as lead or tungsten). By setting a blocking array plate between the imaging source 200 and the imager 400, during the imaging process, the rays emitted by the imaging source 200 are blocked by the blocking pillars on the blocking array plate, thereby forming corresponding shadow areas on the imager 400. For example, if the blocking array plate 300 has 20 blocking pillars, 20 shadow areas (shadow points) will be formed on the imager 400. Since the shadow areas cannot receive the ray signals emitted by the imaging source 200, the signals generated by the shadow areas are scattered signals. By using the low-frequency characteristics of scattering and interpolation processing based on the scattered signals of the shadow areas, the distribution of the overall scattered signal in the projected image can be estimated.

[0089] Based on this, in order to estimate the overall scattering signal distribution in the projected image, in this embodiment, the calibration device 100 is connected to the imager 400 to obtain the projected image formed by the imaging beam passing through the blocking array plate 300, as well as the scattering sampling points corresponding to each blocking column in the projected image. Based on the scattering signal of each two adjacent scattering sampling points, interpolation is performed in the gap between each two adjacent scattering sampling points to obtain interpolated sampling points. Based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution map corresponding to the projected image is obtained.

[0090] Since there are gaps between the blocking pillars, after obtaining the scattering sampling points corresponding to each blocking pillar in the projected image, during interpolation, the interpolation sampling points can be obtained by interpolating the scattering signals between every two adjacent scattering sampling points in the gaps between them. Figure 3 As shown, Figure 3 (a) in the image is the projected image formed by the blocking array plate 300. The points in (a) represent the scattering sampling points corresponding to the blocking pillars. Then, based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain... Figure 3 The image shown in Figure (b) contains scattering sampling points (black points) and interpolation sampling points (white points), which form a rectangular array.

[0091] In this embodiment, since there are gaps between each blocking pillar, interpolation is performed on the gaps between each two adjacent scattering sampling points to fill in the missing values ​​between each two adjacent scattering sampling points. In order to improve the accuracy of scattering estimation, after filling in the missing values ​​between each two adjacent scattering sampling points to obtain interpolated sampling points, it is also necessary to estimate the scattering distribution between the scattering sampling points and the interpolated sampling points. Therefore, after obtaining the interpolated sampling points, it is also necessary to estimate the scattering signal between the scattering sampling points and the interpolated sampling points based on the scattering signals of each scattering sampling point and each interpolated sampling point, so as to obtain the scattering distribution map corresponding to the projected image.

[0092] When estimating the scattering signal between scattering sampling points and interpolation sampling points based on the scattering signals of each scattering sampling point and each interpolation sampling point, interpolation can be used to interpolate between each scattering sampling point and each interpolation sampling point to obtain the scattering distribution map corresponding to the projected image.

[0093] The imaging system provided in this embodiment blocks the imaging beam using a blocking array plate. After acquiring the projected image formed by the imaging beam passing through the blocking array plate, it determines the scattering sampling points in the projected image corresponding to each blocking column in the blocking array plate. Then, based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between each two adjacent scattering sampling points to obtain interpolated sampling points. Based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution map corresponding to the projected image is obtained. Thus, by using a blocking array plate to block the imaging beam, interpolating in the gaps between each two adjacent scattering sampling points, and then using the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be effectively estimated, improving the accuracy of scattering estimation for the projected image.

[0094] Because of the obstruction by the blocking pillars in the blocking array plate 300, the shadowed area cannot receive the ray signal emitted by the imaging source 200. Therefore, interpolation is needed to complete the ray signal in the shadowed area. However, since the rays emitted by the imaging source 200 are not gradually changing, the more areas are obstructed, the greater the interpolation error will be, thus causing artifacts in the reconstructed image.

[0095] In order to reduce the error caused by ray interpolation when reconstructing images, in this embodiment, the number of blocking pillars in the illumination area of ​​the imaging source 200 can be reduced, thereby reducing the number of shadows in each layer of the projected image obtained by the imager 400, and thus reducing the error caused by ray interpolation when reconstructing images.

[0096] Therefore, in this embodiment, in order to reduce the number of blocking pillars in the illumination area of ​​the imaging source 200 and to facilitate interpolation calculations, such as Figure 4As shown, the blocking array plate can be arranged in multiple rows of columns along the first direction, each row of columns including multiple blocking columns arranged along the second direction, wherein the blocking columns in adjacent rows of columns are staggered from each other, and the first direction and the second direction are perpendicular.

[0097] In this design, the spacing between each row of columns is the same, and the spacing between each blocking column within each row is also the same. By staggering the blocking columns in adjacent rows, and making the first and second directions perpendicular, there are gaps between adjacent blocking columns in both the first and second directions, reducing the shadow area in the projected image. Furthermore, due to the distribution of the blocking column array, interpolation of the gaps between blocking columns can be performed directly in either the first or second direction, within the gaps between every two adjacent blocking columns, to obtain interpolation sampling points. This method is convenient to calculate and has high processing efficiency.

[0098] In order to facilitate control over the number of shadows in the projected image, in this embodiment, the imaging system also includes an array plate driving device.

[0099] The array plate drive device is mounted on the frame and connected to both the blocking array plate 300 and the calibration device 100. The array plate drive device is used to drive the blocking array plate 300 to rotate under the control of the calibration device 100.

[0100] In this embodiment, the array plate driving device can be a motor, electrically connected to the calibration device 100 and mechanically connected to the blocking array plate 300. When it is necessary to control the rotation of the blocking array plate 300, the calibration device 100 can send a rotation command to the array plate driving device, causing the array plate driving device to rotate, thereby driving the blocking array plate 300 to rotate. The rotation command can include the rotation angle of the blocking array plate. When the array plate driving device receives the rotation command, it can rotate according to the rotation angle included in the rotation command. For example, if the rotation angle in the rotation command sent by the calibration device is 45°, then the array plate driving device will drive the blocking array plate to rotate 45° after receiving the rotation command.

[0101] In this embodiment, controlling the rotation of the blocking array plate 300 means controlling the blocking array plate 300 to rotate within the illumination surface of the imaging source 200, that is, controlling the blocking array plate 300 to rotate about an axis perpendicular to the illumination surface of the imaging source 200. Figure 5 As shown, the xz plane is the illumination surface of the imaging source 200, and the y-axis is the axis perpendicular to the xz plane. The blocking array plate 300 is controlled to rotate on the illumination surface of the imaging source 200, that is, the blocking array plate 300 is controlled to rotate around the y-axis.

[0102] In this embodiment, when controlling the rotation of the blocking array plate 300, the rotation of the blocking array plate 300 can be controlled by a preset angle. The preset angle can be set according to actual needs; this embodiment does not specify a particular requirement.

[0103] In this embodiment, after the blocking array plate 300 is rotated, the illumination area of ​​the imaging source 200 remains unchanged, but the blocking column array on the blocking array plate 300 tilts. This results in a reduction in the number of blocking columns on the blocking array plate 300 within the illumination area of ​​the imaging source 200, thereby reducing the number of shadows in each layer of the projected image acquired by the imager 400. For example, Figure 6 As shown, Figure 6 In the diagram, (a) represents the unrotated blocking array plate. Figure 6 (b) shows the blocking array plate after being rotated 45°. The density of the blocking columns in the blocking array plate 300 is the same in both (a) and (b). In (a), there are 9 blocking columns per row and 9 blocking columns per column within the irradiation area. After the blocking array plate is rotated 45°, the columns of blocking columns on the blocking array plate 300 tilt, causing the number of blocking columns per row and column in the irradiation area of ​​(b) to decrease from 9 to 6-7. The system consists of 7 blocking bars in odd-numbered rows and columns, and 6 blocking bars in even-numbered rows and columns. Each blocking bar in an even-numbered row is positioned between two adjacent blocking bars in an odd-numbered row, and each blocking bar in an even-numbered column is positioned between two adjacent blocking bars in an odd-numbered column.

[0104] This embodiment controls the number of blocking columns within the illumination area of ​​the imaging source by rotating the blocking array plate within the illumination surface of the imaging source. This reduces the number of shadows in each layer of the projected image obtained by the imager 400. Thus, when reconstructing the image based on the projected image formed by the rotating blocking array plate, the error caused by ray interpolation during image reconstruction can be reduced.

[0105] Currently, most blocking pillars on blocking array plates are vertically positioned, parallel to the axis perpendicular to the illumination surface. However, vertically positioned blocking pillars cause excessive pixel obstruction at the edges, and because the attenuation path of edge rays passing through the blocking pillars is relatively small, incomplete obstruction can occur, leading to signal interference in the shadow areas of the projected image and reducing the accuracy of scattering estimation. Therefore, in this embodiment, all blocking pillars on the blocking array plate can be oriented towards the imaging light source; that is, in this embodiment, the intersection of the central axes of all blocking pillars coincides with the imaging focal point of the imaging source. Figure 7As shown, all the blocking pillars are embedded towards the imaging light source, so that the intersection of the central axes of each blocking pillar coincides with the imaging focal point of the imaging source. This ensures that the ray shadow range of each blocking pillar is consistent, and the ray attenuation path is consistent, guaranteeing complete occlusion by the blocking pillars and thus improving the accuracy of subsequent scattering estimation.

[0106] The imaging system provided in this embodiment reduces the number of blocking pillars within the illumination area of ​​the imaging light source by controlling the rotation of the blocking array plate within the illumination surface of the imaging light source. This reduces the number of shadows in each layer of the projected image and minimizes errors caused by ray interpolation during image reconstruction. Furthermore, in this embodiment, the intersection of the central axes of each blocking pillar coincides with the imaging focal point of the imaging source, ensuring that the ray shadow range of each blocking pillar is consistent and the ray attenuation path is consistent, guaranteeing complete occlusion by the blocking pillars and thus improving the accuracy of subsequent scattering estimation.

[0107] Based on the architecture of the imaging system described above, this embodiment provides a scattering estimation method, applied to... Figure 1 The correction device 100 in the embodiment performs the scattering estimation method provided in this embodiment.

[0108] Please refer to the following: Figure 8 , Figure 8 This is a structural block diagram of the calibration device 100 provided in this embodiment. Figure 8 As shown, the calibration device 100 may include a memory 20, a processor 30, and a communication unit 40. The memory 20 stores machine-readable instructions that can be executed by the processor 30. When the calibration device 100 is running, the processor 30 and the memory 20 communicate via a bus. The processor 30 executes the machine-readable instructions and performs a scattering estimation method.

[0109] The memory 20, processor 30, and communication unit 40 are electrically connected directly or indirectly to each other to achieve signal transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines. The processor 30 is used to execute executable modules stored in the memory 20.

[0110] The memory 20 may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0111] In some embodiments, processor 30 is used to perform one or more functions described in this embodiment. In some embodiments, processor 30 may include one or more processing cores (e.g., a single-core processor (S) or a multi-core processor (S)). By way of example only, processor 30 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), an application-specific instruction-set processor (ASIP), a graphics processing unit (GPU), a physical processing unit (PPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic controller (PLC), a microcontroller unit, a reduced instruction set computing (RISC) computer, or a microprocessor, or any combination thereof.

[0112] For ease of explanation, only one processor is described in the calibration device 100. However, it should be noted that the calibration device 100 in this embodiment may also include multiple processors, and therefore the steps performed by one processor as described in this embodiment may also be performed jointly or individually by multiple processors. For example, if the processor of the calibration device 100 performs steps A and B, it should be understood that steps A and B may also be performed jointly by two different processors or individually by one processor. For example, one processor performs step A, and a second processor performs step B, or the first and second processors jointly perform steps A and B.

[0113] In this embodiment, the memory 20 is used to store the program, and the processor 30 is used to execute the program after receiving the execution instruction. The process definition method disclosed in any implementation of this embodiment can be applied to the processor 30, or implemented by the processor 30.

[0114] The communication unit 40 is used to establish a communication connection between the calibration device 100 and other devices via a network, and to send and receive data via the network.

[0115] In some implementations, the network can be any type of wired or wireless network, or a combination thereof. By way of example only, the network may include wired networks, wireless networks, fiber optic networks, telecommunications networks, intranets, the Internet, local area networks (LANs), wide area networks (WANs), wireless local area networks (WLANs), metropolitan area networks (MANs), public switched telephone networks (PSTNs), Bluetooth networks, ZigBee networks, or near field communication (NFC) networks, or any combination thereof.

[0116] In this embodiment, the calibration device 100 can be a computer device that directly issues control commands, such as a host computer device.

[0117] Understandably, Figure 8 The structure shown is for illustrative purposes only. The calibration device 100 may also have a higher... Figure 8 Showing more or fewer components, or having with Figure 8 The different configurations shown. Figure 8 The components shown can be implemented using hardware, software, or a combination thereof.

[0118] based on Figures 1 to 8 The structural diagram shown illustrates in detail the steps of the scattering estimation method provided in this embodiment. Please refer to the attached diagram. Figure 9 The scattering estimation method provided in this embodiment includes steps S101 to S104.

[0119] Step S101: Acquire the projected image formed by the imaging beam passing through the blocking array plate.

[0120] In this process, after the imaging source is turned on, the imaging beam emitted by the imaging source shines onto the imager through the blocking array plate. The imager receives the imaging beam that has passed through the blocking array plate and converts it into projection data. The correction device can obtain the projected image by acquiring the projection data of the imager.

[0121] Step S102: Obtain the scattering sampling points corresponding to each blocking pillar in the projected image.

[0122] Because the blocking array plate has multiple blocking pillars, the rays emitted by the imaging source will be blocked by the blocking pillars on the blocking array plate during the imaging process, resulting in shadow areas in the obtained projection image that are blocked by each blocking pillar.

[0123] In this embodiment, all the blocking pillars are embedded towards the imaging source, and the intersection of the central axes of each blocking pillar coincides with the imaging focal point of the imaging source. This ensures that the ray shadow range of each blocking pillar is consistent and the ray attenuation path is consistent, thus ensuring complete occlusion by the blocking pillars and improving the accuracy of subsequent scattering estimation.

[0124] Since the shadowed areas cannot receive the ray signals emitted by the imaging source, the signals generated by the shadow points are scattered signals. Based on this, this embodiment can acquire the shadowed areas in the projected image, and determine the scattering sampling points corresponding to each blocking pillar in the projected image based on the shadowed areas. Optionally, the center of the shadowed area can be set as the scattering sampling point.

[0125] Step S103: Based on the scattering signals of every two adjacent scattering sampling points, interpolate the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points.

[0126] Since there are gaps between each blocking pillar, after obtaining the scattering sampling points corresponding to each blocking pillar in the projected image, when performing interpolation, the interpolation points between each pair of adjacent scattering sampling points can be obtained by interpolating the scattering signals between each pair of adjacent scattering sampling points in the gaps between each pair of adjacent scattering sampling points.

[0127] In this embodiment, after interpolation is performed on the gaps between every two adjacent scattering sampling points, each scattering sampling point and each interpolated sampling point form a rectangular array, such as... Figure 3 As shown, Figure 3 Figure (a) is the projected image formed by the blocking array plate 300. The points in (a) represent the scattering sampling points corresponding to the blocking pillars. Figure (b) is the image obtained after interpolation. The points in Figure (b) include scattering sampling points and interpolation sampling points. It can be seen from Figure (b) that the scattering sampling points and interpolation sampling points form a rectangular array.

[0128] Optionally, in this embodiment, when interpolating the gaps between every two adjacent scattering sampling points, spline interpolation, polynomial interpolation, linear interpolation, Lagrange polynomial interpolation, etc., can be used, and there is no specific limitation. Since the scattering distribution of the projected image has low-frequency characteristics, spline interpolation can be used in this embodiment. Optionally, in this embodiment, cubic spline interpolation can be used to interpolate the gaps between every two adjacent scattering sampling points.

[0129] Step S104: Based on the scattering signals of each scattering sampling point and each interpolation sampling point, obtain the scattering distribution map corresponding to the projected image.

[0130] In this embodiment, since there are gaps between the blocking pillars, interpolation is performed on the gaps between every two adjacent scattering sampling points to fill in the missing values. To improve the accuracy of scattering estimation, after filling in the missing values ​​between every two adjacent scattering sampling points to obtain interpolated sampling points, it is also necessary to estimate the scattering distribution between the scattering sampling points and the interpolated sampling points. Optionally, after obtaining the interpolated sampling points, interpolation can be performed between the scattering sampling points and the interpolated sampling points based on the scattering signals of each scattering sampling point and each interpolated sampling point to obtain the scattering distribution between the scattering sampling points and the interpolated sampling points, thereby obtaining the scattering distribution map corresponding to the projected image.

[0131] When interpolating between scattering sampling points and interpolation sampling points, spline interpolation, polynomial interpolation, linear interpolation, Lagrange polynomial interpolation, and other interpolation methods can be used, without any specific limitation. Optionally, in this embodiment, cubic spline interpolation can be used to interpolate between scattering sampling points and interpolation sampling points.

[0132] The scattering estimation method provided in this embodiment blocks the imaging beam using a blocking array. After acquiring the projected image formed by the imaging beam passing through the blocking array, the scattering sampling points corresponding to each blocking column in the blocking array are determined. Then, based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between each pair of adjacent scattering sampling points to obtain interpolated sampling points. Based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution map corresponding to the projected image is obtained. Thus, by blocking the imaging beam using a blocking array, interpolating in the gaps between each pair of adjacent scattering sampling points, and then using the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be effectively estimated, improving the accuracy of scattering estimation for the projected image.

[0133] Since the object under test itself scatters the imaging beam during scanning, affecting the identification of scattering sampling points, for example, scattering points generated by the object under test might be used as scattering sampling points when determining scattering sampling points in the projected image. To improve accuracy, in this embodiment, projected images can be acquired with and without the object under test. Therefore, the projected images in this embodiment include a first projected image and a second projected image, wherein the first projected image is the projected image formed without the object under test, and the second projected image is the projected image formed with the object under test.

[0134] When acquiring the first projected image, the calibration device can directly acquire the first projected image formed by the imaging light source through the blocking array plate after the imaging light source is turned on. When acquiring the second projected image, the object to be tested can be placed within the illumination surface of the imaging light source, and after the imaging light source is turned on, it can scan the object to be tested through the blocking array plate. The calibration device then acquires the second projected image through the imager.

[0135] After obtaining the first and second projected images, the scattering sampling points corresponding to each blocking pillar can be obtained based on the first and second projected images. Optionally, this can be achieved through the following steps:

[0136] Obtain the center point of the shadow area blocked by each blocking pillar in the first projected image.

[0137] Based on the center point of each shadow region, the target point corresponding to the center point of each shadow region is obtained in the second projection image, and the target point is set as the scattering sampling point in the second projection image.

[0138] Since the position of the blocking array plate did not change when acquiring the first and second projected images, the shadow areas in the first and second projected images are the same. Because the first projected image is obtained without the object under test placed, and the second projected image is obtained with the object under test placed, the scattered signals in the shadow areas blocked by the blocking pillars in the first projected image are the scattered signals generated by the imaging source illuminating the blocking array plate. The scattered signals in the shadow areas blocked by the blocking pillars in the second projected image include the scattered signals generated by the imaging source passing through the object under test.

[0139] Since the first projection image is obtained without the object to be tested being placed, and the second projection image is obtained with the object to be tested being placed, in order to accurately obtain the scattering sampling points of the projection images, in this embodiment, the center point of the shadow area blocked by each blocking pillar in the first projection image can be obtained first, and then, based on the center point of each shadow area, the target point corresponding to the center point of each shadow area can be obtained in the second projection image, that is, the target point with the same position as the center point of each shadow area, and the target point can be set as the scattering sampling point in the second projection image.

[0140] To improve accuracy, the center point of the shadowed area obscured by each blocking pillar in the first projected image can be obtained through the following steps:

[0141] (1) Analyze and process the pixels in the first projected image to determine the shadow pixels corresponding to the shadow areas blocked by each blocking pillar.

[0142] (2) Determine the center point of the shadow area in the first projected image that is blocked by each blocking pillar based on the shadow pixels.

[0143] In the process of analyzing and processing the pixels in the first projected image to determine the shadow pixels corresponding to the shadow areas blocked by each blocking pillar, each pixel in the first projected image can be filtered according to the set projection threshold to obtain the shadow pixels corresponding to the shadow areas blocked by each blocking pillar in the first projected image.

[0144] Optionally, the penumbra effect and noise influence can be considered, and a projection threshold can be set. In this embodiment, when filtering each pixel in the first projected image according to the projection threshold, pixels with pixel values ​​less than the projection threshold can be set as occluded shadow pixels, i.e., shadow pixels belonging to the shadow area, and pixels with pixel values ​​not less than the projection threshold can be set as unoccluded pixels, i.e., shadow pixels not belonging to the shadow area. To facilitate the distinction between occluded and unoccluded pixels, the pixel value of occluded shadow pixels can be set to 0, and the pixel value of unoccluded pixels can be set to 1.

[0145] In an optional implementation, a first marker can be set for occluded shadow pixels, and a second marker can be set for unoccluded pixels. The first and second markers can be any type of marker symbol, such as numbers, letters, strings, etc., without specific limitations, as long as they are distinguishable. For example, the first marker can be set to 0 for occluded shadow pixels, and the second marker can be set to 1 for unoccluded pixels.

[0146] After obtaining the shadow pixels in the first projected image, the center point of the shadow area blocked by each blocking pillar in the first projected image can be determined based on the shadow pixels in the first projected image.

[0147] Specifically, when determining the center point of the shadow area blocked by each blocking pillar in the first projected image based on the shadow pixels in the first projected image, the connected regions of each shadow pixel in the first projected image can be found, and then the determined connected regions are identified as the shadow areas blocked by the blocking pillars.

[0148] When searching for the connected regions of each shadow pixel in the first projected image, for each shadow pixel, a neighborhood can be set to search for the connected regions of that shadow pixel. The set neighborhood can be an 8-neighborhood, a 4-neighborhood, etc., and there is no specific restriction.

[0149] For example, when searching for connected components using the 8-neighborhood method, for each shaded pixel, it is determined whether the labels of the pixels in the eight directions above, below, left, right, upper left, upper right, lower left, and lower right of the shaded pixel's location are the first label, i.e., whether they are the same as the shaded pixel's label. Then, the pixels with the first label are grouped into the same connected component, and so on, until all connected components of shaded pixels are found. Alternatively, it is determined whether the values ​​of the pixels in the eight directions above, below, left, right, upper left, upper right, lower left, and lower right of the shaded pixel's location are 0, i.e., whether they are the same as the shaded pixel's value. Then, the pixels with a value of 0 are grouped into the same connected component, and so on, until all connected components of shaded pixels are found.

[0150] When searching for connected regions using the 4-neighborhood method, for each shaded pixel, it is determined whether the pixels above, below, left, and right of the shaded pixel's location are marked as the first marker. Then, the pixels marked as the first marker are grouped into the same connected region, and so on, until all connected regions of shaded pixels are found. Alternatively, it is determined whether the values ​​of the pixels above, below, left, and right of the shaded pixel's location are 0, i.e., whether they are the same as the value of the shaded pixel. Then, the pixels with values ​​of 0 are grouped into the same connected region, and so on, until all connected regions of shaded pixels are found.

[0151] Understandably, each connected region found corresponds to a shadowed region obscured by the blocking pillars. By finding the shadowed regions obscured by each blocking pillar in the first projected image, the center point of the shadowed region obscured by the blocking pillars in the first projected image can be determined.

[0152] Understandably, the center point of the shadowed area obscured by the blocking pillar in the first projected image is the scattering sampling point in the first projected image. Since the shadowed areas in the first and second projected images are the same, after determining the center point of the shadowed area obscured by the blocking pillar in the first projected image, the target point corresponding to the center point of each shadowed area can be obtained in the second projected image based on the center point of each shadowed area.

[0153] When obtaining the target point corresponding to the center point of each shadow region in the second projection image, the position of each center point in the first projection image can be used to find the same position in the second projection image. This same position is then used as the position of the target point, thus determining the scattering sampling point in the second projection image. For example, if a center point is located at row A, column B in the first projection image, then the position at row A, column B in the second projection image can be found, and this point in the second projection image can be used as the target point corresponding to that center point.

[0154] After obtaining the target point in the second projected image, the scattering sampling point in the second projected image can be obtained.

[0155] After obtaining the scattering sampling points in the first and second projected images, interpolation can be performed based on the scattering signals of the scattering sampling points to obtain the interpolated sampling points. Since the second projected image is the projected image formed with the object to be measured placed on it, and the first projected image is the projected image formed without the object to be measured placed on it, in order to reduce the amount of computation, interpolation calculations can be performed only on the second projected image.

[0156] Optionally, the step of interpolating the gaps between every two adjacent scattering sampling points based on the scattering signals of every two adjacent scattering sampling points to obtain interpolated sampling points may include:

[0157] Acquire the scattering signal of each scattering sampling point within a set pixel range.

[0158] Based on the scattering signals of every two adjacent scattering sampling points within a set pixel range, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points.

[0159] The pixel range can be set according to actual needs, and there are no restrictions on its specifics, such as a pixel range of m*n, where m and n are positive integers.

[0160] In this embodiment, when interpolating the scattering signals of every two adjacent scattering sampling points within a set pixel range, the average or median of the scattering signals of every two adjacent scattering sampling points within the set pixel range can be calculated. Interpolation is then performed based on the average or median value within the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points. Alternatively, the scattering signals of the scattering sampling points within the set pixel range can be smoothed using methods such as Gaussian filtering or bilateral filtering to obtain smoothed values. When interpolating the scattering signals of every two adjacent scattering sampling points within the set pixel range, the smoothed values ​​can be used to interpolate within the gaps between every two adjacent scattering sampling points.

[0161] In this embodiment, as Figure 4 As shown, the blocking array plate is arranged with multiple rows of columns along the first direction, and each row of columns includes multiple blocking columns arranged along the second direction. The blocking columns in adjacent rows of columns are staggered from each other, and the first direction and the second direction are perpendicular.

[0162] In this design, the spacing between each row of columns is the same, and the spacing between each blocking column within each row is also the same. By staggering the blocking columns in adjacent rows, with the first and second directions perpendicular, there are gaps between adjacent blocking columns in both the first and second directions, reducing shadow areas in the projected image. Furthermore, due to the distribution of the blocking column array, interpolation of the gaps between blocking columns can be performed directly in either the first or second direction, within the gaps between every two adjacent blocking columns, yielding interpolation sampling points. This method is convenient and efficient.

[0163] Interpolation is performed in the gaps between every two adjacent blocking pillars in either the first or second direction, which is a one-dimensional interpolation. Therefore, the interpolation direction can be determined first from the first and second directions, and then, in the interpolation direction, interpolation is performed between every two adjacent scattering sampling points based on the average, median, or smoothed value of the scattering signal within a set pixel range.

[0164] For example, Figure 10 As shown, the Z-axis (second direction) is set as the interpolation direction, and interpolation is performed using the average value. When interpolating between scattering sampling point A and scattering sampling point B, the interpolation is performed based on the average value of the scattering signal at scattering sampling point A within a set pixel range and the average value of the scattering signal at scattering sampling point B within the set pixel range. Figure 10 The sampling point map shown can be obtained by interpolating between every two adjacent scattering sampling points along the Z-axis. Figure 11 The diagram shows a 13×13 grid sampling point map.

[0165] Optionally, in the interpolation direction, interpolation between two adjacent scattering sampling points can be performed using one-dimensional cubic spline interpolation, based on the average, median, or smooth value of the scattering signal within a set pixel range for each pair of adjacent scattering sampling points.

[0166] Through the above process, after interpolating the gaps between every two adjacent scattering sampling points, the interpolated sampling points between every two adjacent scattering sampling points can be obtained. Since interpolating the gaps between every two adjacent scattering sampling points fills in the missing values ​​between them, and to improve the accuracy of scattering estimation, after filling in the missing values ​​between every two adjacent scattering sampling points and obtaining the interpolated sampling points, it is also necessary to estimate the scattering distribution between the scattering sampling points and the interpolated sampling points. Therefore, after obtaining the interpolated sampling points, it is also necessary to obtain the scattering signal between the scattering sampling points and the interpolated sampling points based on the scattering signals of each scattering sampling point and each interpolated sampling point, thereby obtaining the scattering distribution map corresponding to the projected image.

[0167] Optionally, the step of obtaining the scattering distribution map corresponding to the projected image based on the scattering signals of each scattering sampling point and each interpolation sampling point includes:

[0168] Based on the scattering signals of each scattering sampling point within a set pixel range, and the scattering signals of each interpolation sampling point, interpolation or fitting is performed between each scattering sampling point and each interpolation sampling point to obtain a scattering distribution map.

[0169] In the process of interpolating or fitting between scattering sampling points and interpolation sampling points based on the scattering signals of each scattering sampling point within a set pixel range and the scattering signals of each interpolation sampling point, the average, median, or smoothed value of the scattering signals of each scattering sampling point within the set pixel range can be calculated first. Then, interpolation can be performed between each scattering sampling point and each interpolation sampling point based on the scattering signals of each interpolation sampling point and the average, median, or smoothed value of the scattering signals of each scattering sampling point within the set pixel range. Alternatively, fitting can be performed between each scattering sampling point and each interpolation sampling point based on the scattering signals of each interpolation sampling point and the average, median, or smoothed value of the scattering signals of each scattering sampling point within the set pixel range to obtain the scattering distribution between each scattering sampling point and each interpolation sampling point, thereby obtaining the overall scattering distribution map.

[0170] When interpolating between interpolation sampling points based on the scattering signals of each interpolation sampling point and the average, median, or smoothed value of the scattering signals of each scattering sampling point within a set pixel range, it is a two-dimensional interpolation. Therefore, when performing interpolation, the values ​​of surrounding adjacent sampling points must be considered, that is, the values ​​of adjacent sampling points in the first and second directions. For example, as... Figure 12 As shown, taking the average value as an example, when interpolating between scattering sampling point 1 and interpolation sampling point 1, it is necessary to consider the average value of the scattering signal of scattering sampling point 1 within the set pixel range, the scattering signal value of interpolation sampling point 1, the average value of the scattering signal of scattering sampling point 2 within the set pixel range, and the scattering signal value of interpolation sampling point 2, and then perform the interpolation.

[0171] Optionally, when interpolating between each scattering sampling point and each interpolation sampling point, two-dimensional cubic spline interpolation can be used.

[0172] When fitting between each scattering sampling point and each interpolation sampling point based on the scattering signal of each interpolation sampling point and the average, median, or smoothed value of the scattering signal of each scattering sampling point within a set pixel range, it is necessary to fit based on the overall signal value of the sampling points. To illustrate with the average value, we can first calculate the average value of the scattering signal of each scattering sampling point within the set pixel range, and then fit a two-dimensional surface based on the average value of the scattering signal of each scattering sampling point within the set pixel range and the signal value of each interpolation sampling point. This two-dimensional surface represents the overall scattering distribution of the projected image.

[0173] When fitting the data, various fitting methods can be used, such as multinomial fitting and locally weighted regression fitting, without any specific restrictions.

[0174] After estimating the scattering distribution between each scattering sampling point and each interpolation sampling point through the above process, the scattering distribution map corresponding to the projected image can be obtained.

[0175] The scattering estimation method provided in this embodiment blocks the imaging beam by setting up a blocking array plate, interpolates in the gaps between every two adjacent scattering sampling points, and then accurately estimates the scattering distribution of the projected image based on the scattering signals of each scattering sampling point and each interpolated sampling point, thereby improving the accuracy of scattering estimation of the projected image.

[0176] In this embodiment, the scattering distribution map represents the overall scattering signal distribution of the projected image. Therefore, after obtaining the scattering distribution map, the projected image can be corrected according to the scattering distribution map to obtain the ray distribution map corresponding to the projected image.

[0177] In this process, the projection image is corrected based on the scattering distribution map. This can be achieved by subtracting the corresponding scattering signal from the projection image, thus obtaining the ray distribution map that passes through the object under test.

[0178] Optionally, in this embodiment, the step of correcting the second projection image based on the scattering distribution map to obtain the ray distribution map may include:

[0179] (1) Determine the ray signal of the target projection area in the projected image that is not blocked by each blocking pillar.

[0180] (2) Determine the scattering signal of the target scattering region corresponding to the target projection region in the scattering distribution map.

[0181] (3) Based on the scattering signal of the target scattering area, the ray signal of the target projection area is corrected to obtain the ray distribution map.

[0182] In this diagram, the signal from the obstructed area in the projected image is the scattering signal, while the signal from the unobstructed area is the ray signal from the imaging light source. Therefore, when correcting the scattering of the signal from the unobstructed area in the projected image based on the scattering distribution map, we can first determine the target projection area not obstructed by the obstructing pillars and its ray signal, and then determine the target scattering area corresponding to the target projection area and its scattering signal in the scattering distribution map. Finally, based on the scattering signal of the target scattering area, we correct the ray signal of the target projection area to obtain the ray distribution map.

[0183] In determining the target scattering region and the scattering signal of the target scattering region corresponding to the target projection region in the scattering distribution map, the region with the same position can be found in the scattering distribution map based on the position of the target projection region. The found region is taken as the target scattering region, and then the scattering signal of the target scattering region is obtained.

[0184] In this embodiment, the target scattering area and the target projection area are located at the same position. The signal of the target scattering area is a scattered signal, while the signal of the target projection area includes the main ray signal transmitted through the object under test and the scattered signal. Therefore, to correct the ray signal of the target projection area, it is necessary to remove the scattered signal. At the same time, due to the obstruction of the blocking pillar, the obstructed area in the projection image will lack the main ray signal. Therefore, it is also necessary to supplement the main ray signal in the obstructed area.

[0185] Based on this, in this embodiment, the step of correcting the ray signal of the target projection area according to the scattering signal of the target scattering area to obtain the ray distribution may include:

[0186] The difference between the ray signal in the target projection area and the scattering signal in the target scattering area is calculated to obtain the initial ray distribution map.

[0187] Based on the location of each scattering sampling point, the ray points to be interpolated in the initial ray distribution map are determined.

[0188] Based on the ray signals in the initial ray distribution map, the ray points of the value to be checked are interpolated to obtain the ray distribution map.

[0189] The difference calculation between the ray signal of the target projection area and the scattering signal of the target scattering area can be achieved by subtracting the value of the ray signal of the target scattering area from the value of the ray signal of the target projection area to obtain the value of the main ray signal of the target projection area, thereby obtaining the initial ray distribution map.

[0190] For areas not blocked by obstructing pillars, the value of the main ray signal needs to be greater than 0. Therefore, when calculating the difference between the ray signal of the target projection area and the scattering signal of the target scattering area, it is necessary to truncate the scattering signal of the target scattering area based on the ray signal of the target projection area so that the scattering signal of the target scattering area is less than the ray signal of the target projection area.

[0191] Specifically, when truncating the scattering signal of the target scattering region based on the ray signal of the target projection region, it is necessary to detect whether the value of the scattering signal of the target scattering region is greater than or equal to the value of the ray signal of the target projection region. If it is greater than or equal to the value of the ray signal of the target projection region, the value of the scattering signal of the target scattering region needs to be recalculated so that the value of the scattering signal of the target scattering region is less than the value of the ray signal of the target projection.

[0192] In an optional implementation, the value of the scattered signal of the target scattering region can be recalculated based on the scattered signals from its neighboring regions. For example, the average or variance of the scattered signals from the surrounding regions can be calculated, and these parameters can be used as the value of the scattered signal from the target scattering region. Alternatively, a mapping relationship between signal intervals and target signal values ​​can be established beforehand based on multiple experimental data. When recalculating the scattered signal of the target scattering region, the target signal interval in which the scattered signal of the target region falls can be located. Then, according to the mapping relationship, the target target signal value corresponding to the target signal interval can be found, and the value of the target target signal value can be used as the value of the scattered signal from the target scattering region.

[0193] This embodiment calculates the difference between the ray signal of the target projection area and the scattering signal of the target scattering area, thereby removing the scattering signal from the ray signal of the target projection area and achieving scattering correction of the projection area.

[0194] Because of the obstruction of the blocking pillars, the obstructed areas will lack the main ray signal. Therefore, after obtaining the initial ray distribution map, it is necessary to supplement the main ray in the areas obstructed by the blocking pillars in the initial ray distribution map.

[0195] In this embodiment, since the location blocked by the blocking pillar is the location of the scattering sampling point, the ray point to be interpolated in the initial ray distribution map can be determined based on the location of the scattering sampling point. That is, for each scattering sampling point, a point with the same location is found in the initial ray distribution map based on the location of the scattering sampling point, and the found point is set as the ray point to be interpolated. In this embodiment, a corresponding ray point can be found in the initial ray distribution map for each scattering sampling point.

[0196] After obtaining the ray points to be interpolated in the initial ray distribution map, the ray points to be interpolated can be interpolated according to the ray signals in the initial ray distribution map to obtain the ray distribution map.

[0197] In this embodiment, when interpolating the ray points to be interpolated based on the ray signals in the initial ray distribution, either one-dimensional interpolation or two-dimensional interpolation can be used. With one-dimensional interpolation, for each ray point, in the first or second direction, the signal value to be interpolated corresponding to that ray point is calculated based on the ray signal values ​​of the two points (pixels) adjacent to that ray point. For example, in the second direction, if ray point A is to be interpolated, the signal value corresponding to ray point A needs to be calculated based on the ray signal values ​​of the two points to its left and right. With two-dimensional interpolation, for each ray point, the signal value to be interpolated corresponding to that ray point is calculated based on the ray signal values ​​of the points surrounding that ray point (including the first and second directions). For example, if ray point A is to be interpolated, the signal value corresponding to ray point A needs to be calculated based on the ray signal values ​​of the four points above, below, left, and right of ray point A, that is, the points adjacent to ray point A in the horizontal direction and the points adjacent to ray point A in the vertical direction.

[0198] After interpolating the ray points in the initial ray distribution map, the main ray signal in the projected image is supplemented, and the ray distribution map corresponding to the projected image is obtained.

[0199] In an optional implementation, this embodiment may first calculate the ray points to be interpolated in the projected image, complete the main ray signals of the ray points to be interpolated, and then perform scattering correction. Based on this, please refer to [the relevant documentation]. Figure 13 In this embodiment, after obtaining the scattering distribution map corresponding to the projected image, the scattering estimation method provided in this embodiment further includes steps S201 to S203.

[0200] Step S201: Determine the ray points to be interpolated in the projected image based on the positions of each scattering sampling point.

[0201] Step S202: Based on the ray signals in the projected image, interpolate the ray points to be interpolated to obtain the interpolated projected image.

[0202] Step S203: Based on the scattering distribution map, correct the interpolated projection image to obtain the ray distribution map.

[0203] In this case, due to the obstruction of the blocking pillar, the scattering sampling point corresponding to the blocking pillar cannot receive the main ray signal. Therefore, it is necessary to interpolate the main ray to the scattering sampling point. Based on this, in this embodiment, when determining the ray point to be interpolated in the projection image according to the position of each scattering sampling point, each scattering sampling point in the projection image can be used as the ray point to be interpolated in the projection image.

[0204] Once the ray points to be interpolated in the projected image are determined, interpolation can be performed on the ray points based on the ray signals in the projected image.

[0205] When interpolating ray points based on ray signals in a projected image, either one-dimensional or two-dimensional interpolation can be used. In one-dimensional interpolation, for each ray point, the interpolation signal value is calculated based on the ray signal values ​​of the two adjacent points (pixels) in the first or second direction. In two-dimensional interpolation, for each ray point, the interpolation signal value is calculated based on the ray signal values ​​of the surrounding points (including the first and second directions).

[0206] After interpolating the ray points to be interpolated in the projection image to obtain the interpolated projection image, the ray distribution in the projection image is obtained. However, there are still scattering signals in the projection image at this time, and the scattering signals in the projection image need to be removed. Therefore, in the obtained interpolated projection image, it is also necessary to correct the interpolated projection image according to the scattering distribution map to obtain the ray distribution map corresponding to the projection image.

[0207] When correcting the interpolated projection image based on the scattering distribution map, the difference between the interpolated projection image and the scattering distribution map can be calculated directly to remove the scattering signal in the interpolated projection image, thus achieving scattering correction of the interpolated projection image.

[0208] In this embodiment, the ray distribution map represents the signal distribution map formed by the ray signals passing through the object under test. Based on the ray distribution map, image reconstruction can be performed. Therefore, after correcting the projected image to obtain the ray distribution map, the scattering estimation method provided in this embodiment further includes:

[0209] Based on the ray distribution map and the projection image, calculate the attenuation integral image, and then reconstruct the image based on the attenuation integral image.

[0210] To accurately determine the attenuation of the imaging beam when scanning the object under test, this embodiment uses a first projection image and a ray distribution image to calculate an attenuation integral image. The first projection image is the projection image formed when the object under test is not placed, while the ray distribution image represents the signal distribution of the ray signal after passing through the object under test. Therefore, by analyzing the signal values ​​in the first projection image and the ray distribution image, the attenuation of the ray signal generated by the imaging light source as it passes through the object under test can be accurately determined.

[0211] Optionally, in this embodiment, the process of obtaining the attenuation integral image based on the ray distribution map and the first projection image can be achieved using the formula... The image is obtained as follows: L1 is the attenuation integral image, P2 is the ray distribution map, and I1 is the first projection image. After obtaining the attenuation integral image, image reconstruction can be performed using it.

[0212] In this embodiment, image reconstruction is performed using the attenuation integral image. The reconstruction can be performed using algorithms such as analytical reconstruction or iterative reconstruction, and the specific method can be set according to actual needs. This embodiment does not impose any limitations.

[0213] To simplify the process and improve efficiency, this embodiment can also first calculate the attenuation integral image, and then use the attenuation integral image to supplement the main ray signal of the occluded shadow area. Based on this, please refer to [the relevant documentation / reference]. Figure 14 After obtaining the scattering distribution map corresponding to the projected image, the method provided in this embodiment may further include steps S301 to S304.

[0214] Step S301: Correct the projected image according to the scattering distribution map to obtain the corrected image. Calculate the attenuation integral image based on the corrected image and the projected image.

[0215] Step S302: Based on the position of each scattering sampling point, determine the ray point to be interpolated in the attenuation integral image.

[0216] Step S303: Based on the ray attenuation signal in the attenuation integral image, interpolate the ray points to be interpolated to obtain the interpolated attenuation integral image.

[0217] Step S304: Reconstruct the image based on the interpolated attenuation integral image.

[0218] In the process of correcting the projected image based on the scattering distribution map, we can first determine the ray signal of the target projection area that is not blocked by the blocking pillars in the projected image, then determine the scattering signal of the target scattering area corresponding to the target projection area in the scattering distribution map, and finally calculate the difference between the ray signal of the target projection area and the scattering signal of the target scattering area, remove the scattering signal in the projected image, and obtain the corrected image.

[0219] After obtaining the corrected image, the attenuation integral image can be calculated based on the corrected image and the projected image. To accurately determine the attenuation of the imaging beam when scanning the object under test, this embodiment also uses the first projected image and the corrected image to calculate the attenuation integral image. The process of obtaining the attenuation integral image based on the corrected image and the first projected image can be expressed by the formula... We obtain, where L2 is the attenuation integral image, P1 is the correction image, and I1 is the first projection image.

[0220] In this embodiment, the first projection image is the projection image formed when the object under test is not placed, while the correction image represents the signal distribution of the ray signal after passing through the object under test. Therefore, the attenuation integral image calculated based on the first projection image and the correction image represents the attenuation of the ray signal generated by the imaging light source as it passes through the object under test. That is, the signal in the attenuation integral image is the signal after the ray signal has attenuated, i.e., the ray attenuation signal. Therefore, there are scattering sampling points in the attenuation integral image that are in the same position as those in the projection image. When determining the ray point to be interpolated in the attenuation integral image based on the position of each scattering sampling point, the scattering sampling points in the attenuation integral image can be obtained first, and then each scattering sampling point in the attenuation integral image can be used as the ray point to be interpolated in the attenuation integral image.

[0221] Once the ray points to be interpolated in the attenuation integral image are determined, the ray points to be interpolated can be interpolated according to the ray attenuation signal in the attenuation integral image to obtain the interpolated attenuation integral image.

[0222] When interpolating ray points based on the ray attenuation signals in the attenuation integral image, either one-dimensional or two-dimensional interpolation can be used. In one-dimensional interpolation, for each ray point, the interpolation signal value is calculated based on the ray attenuation signal values ​​of the two adjacent points (pixels) in the first or second direction. In two-dimensional interpolation, for each ray point, the interpolation signal value is calculated based on the ray attenuation signal values ​​of the surrounding points (including the first and second directions).

[0223] Once the interpolated attenuation integral image is obtained, it can be used for image reconstruction.

[0224] The scattering estimation method provided in this embodiment reduces the occluded shadow areas in the projected image by setting staggered gaps between the blocking pillars. Furthermore, by performing main ray interpolation to supplement the projected image through the above process, the amount of interpolation can be reduced, thereby reducing the error caused by ray interpolation during image reconstruction and mitigating artifacts in the reconstructed image.

[0225] The scattering estimation method provided in this embodiment blocks the imaging beam using a blocking array plate. Utilizing the low-frequency smoothness of the scattering distribution, interpolation is performed in the gaps between every two adjacent scattering sampling points. Then, based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be accurately estimated, improving the accuracy of scattering estimation. Furthermore, in this embodiment, the intersection of the central axes of each blocking column coincides with the imaging focal point of the imaging source, ensuring a consistent shadow range for each shadow point, further improving the accuracy of scattering estimation.

[0226] Based on the above, this embodiment also provides a readable storage medium, which includes a computer program. When the computer program is executed, it controls the calibration device where the readable storage medium is located to perform the scattering estimation method described in any of the foregoing embodiments.

[0227] The readable storage medium can be, but is not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks, and other media capable of storing program code.

[0228] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the readable storage medium described above can be referred to the corresponding process in the aforementioned method, and will not be elaborated further here.

[0229] In summary, the scattering estimation method, imaging system, correction device, and storage medium provided in this invention, by setting a blocking array plate to obstruct the imaging beam, after acquiring the projected image formed by the imaging beam passing through the blocking array plate, determine the scattering sampling points in the projected image corresponding to each blocking column in the blocking array plate. Then, based on the scattering signals of every two adjacent scattering sampling points, interpolation is performed in the gaps between every two adjacent scattering sampling points to obtain interpolated sampling points. Based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution map corresponding to the projected image is obtained. Thus, by setting a blocking array plate to obstruct the imaging beam, interpolating in the gaps between every two adjacent scattering sampling points, and then based on the scattering signals of each scattering sampling point and each interpolated sampling point, the scattering distribution of the projected image can be effectively estimated, improving the accuracy of scattering estimation of the projected image. Furthermore, by reducing the number of blocking columns in the illumination area of ​​the imaging source by the blocking array plate, the number of shadows in each layer of the projected image obtained by the imager 400 is reduced. When reconstructing the image based on the projected image formed by the rotating blocking array plate on the imager, the error caused by ray interpolation during image reconstruction can be reduced.

[0230] The scattering estimation method, imaging system, correction device, and storage medium provided in the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of the present invention. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of scatter estimation, characterized by, The method comprises: obtaining a projection image formed by an imaging beam passing through a blocking array plate, the blocking array plate comprising a plurality of blocking columns; obtaining a scattering sampling point corresponding to each of the blocking columns in the projection image; interpolating between two adjacent scattering sampling points according to the scattering signals of the two adjacent scattering sampling points to obtain an interpolated sampling point; obtaining a scattering distribution corresponding to the projection image according to the scattering signals of each of the scattering sampling points and each of the interpolated sampling points; wherein the projection image comprises a first projection image and a second projection image; the first projection image is a projection image formed without placing a to-be-tested object; and the second projection image is a projection image formed by placing the to-be-tested object. The step of obtaining a scattering sampling point corresponding to each of the blocking columns in the projection image comprises: analyzing and processing pixels in the first projection image to determine shadow pixels corresponding to shadow regions blocked by each of the blocking columns; determining a center point of the shadow region blocked by each of the blocking columns in the first projection image according to the shadow pixels; obtaining a target point corresponding to the center point of each of the shadow regions in the second projection image according to the center points of each of the shadow regions, and setting the target point as a scattering sampling point in the second projection image.

2. The scatter estimation method of claim 1, wherein, The step of interpolating between two adjacent scattering sampling points according to the scattering signals of the two adjacent scattering sampling points to obtain an interpolated sampling point comprises: obtaining a scattering signal of each of the scattering sampling points within a set pixel range; interpolating between two adjacent scattering sampling points according to the scattering signals of the two adjacent scattering sampling points within the set pixel range to obtain an interpolated sampling point.

3. The scatter estimation method of claim 2, wherein, The step of obtaining a scattering distribution corresponding to the projection image according to the scattering signals of each of the scattering sampling points and each of the interpolated sampling points comprises: interpolating or fitting between each of the scattering sampling points and each of the interpolated sampling points according to the scattering signals of each of the scattering sampling points within the set pixel range and the scattering signals of each of the interpolated sampling points to obtain a scattering distribution.

4. The scatter estimation method of claim 1, wherein, After obtaining the scattering distribution corresponding to the projection image, the method further comprises: correcting the projection image according to the scattering distribution to obtain a ray distribution.

5. The scatter estimation method of claim 4, wherein, The step of correcting the projection image according to the scattering distribution to obtain a ray distribution comprises: determining a ray signal of a target projection region in the projection image that is not blocked by each of the blocking columns; determining a scattering signal of a target scattering region in the scattering distribution corresponding to the target projection region; correcting the ray signal of the target projection region according to the scattering signal of the target scattering region to obtain a ray distribution.

6. The scatter estimation method of claim 5, wherein, The step of correcting the ray signal of the target projection region according to the scattering signal of the target scattering region to obtain a ray distribution comprises: performing difference calculation on the ray signal of the target projection region and the scattering signal of the target scattering region to obtain an initial ray distribution; According to the position of each scattering sampling point, a ray point to be interpolated in the initial ray distribution map is determined; According to the ray signal in the initial ray distribution map, the ray point to be interpolated is interpolated to obtain a ray distribution map.

7. The scatter estimation method of claim 1, wherein, After the scattering distribution map corresponding to the projection image is obtained, the method further comprises: According to the position of each scattering sampling point, a ray point to be interpolated in the initial ray distribution map is determined; According to the ray signal in the initial ray distribution map, the ray point to be interpolated is interpolated to obtain a ray distribution map. After the scattering distribution map corresponding to the projection image is obtained, the method further comprises:

8. The scatter estimation method of claim 4 or 7, wherein, According to the position of each scattering sampling point, a ray point to be interpolated in the initial ray distribution map is determined; According to the ray signal in the initial ray distribution map, the ray point to be interpolated is interpolated to obtain a ray distribution map.

9. The scatter estimation method of claim 1, wherein, After the scattering distribution map corresponding to the projection image is obtained, the method further comprises: According to the scattering distribution map, the interpolated projection image is corrected to obtain a ray distribution map. After the ray distribution map is obtained, the method further comprises: According to the ray distribution map and the projection image, an attenuation integral image is calculated, and image reconstruction is performed according to the attenuation integral image. After the scattering distribution map corresponding to the projection image is obtained, the method further comprises:

10. An imaging system characterized by, According to the scattering distribution map, the projection image is corrected to obtain a corrected image, and an attenuation integral image is calculated according to the corrected image and the projection image; According to the position of each scattering sampling point, a ray point to be interpolated in the initial ray distribution map is determined; According to the ray signal in the initial ray distribution map, the ray point to be interpolated is interpolated to obtain a ray distribution map. After the scattering distribution map corresponding to the projection image is obtained, the method further comprises: The imaging system comprises: A gantry; An imaging source arranged on the gantry; An imager arranged on the gantry opposite the imaging source; A blocking array plate arranged between the imaging source and the imager, the blocking array plate comprising a plurality of blocking columns; A correction device connected to the imager, the correction device being configured to: Obtain a projection image formed by an imaging beam passing through the blocking array plate, the blocking array plate comprising a plurality of blocking columns; obtain scattering sampling points corresponding to each blocking column in the projection image; interpolate between each two adjacent scattering sampling points based on the scattering signals of each two adjacent scattering sampling points to obtain interpolated sampling points; and obtain a scattering distribution map corresponding to the projection image based on the scattering signals of each scattering sampling point and each interpolated sampling point; wherein the projection image comprises a first projection image and a second projection image; the first projection image is a projection image formed without placing a to-be-tested object, and the second projection image is a projection image formed by placing a to-be-tested object; the step of obtaining the scattering sampling points corresponding to each blocking column in the projection image comprises: analyzing and processing pixels in the first projection image to determine shadow pixels corresponding to shadow regions blocked by each blocking column; determining center points of the shadow regions blocked by each blocking column in the first projection image based on the shadow pixels; and obtaining target points corresponding to the center points of each shadow region in the second projection image based on the center points of each shadow region, and setting the target points as the scattering sampling points in the second projection image.

11. The imaging system of claim 10, wherein, The blocking array plate is provided with a plurality of column rows in a first direction, each of the column rows including a plurality of blocking columns arranged in a second direction, wherein the blocking columns in adjacent two column rows are staggered with each other, and the first direction and the second direction are perpendicular.

12. The imaging system of claim 10, wherein, An intersection of central axes of the blocking columns coincides with an imaging focus of the imaging source.

13. The imaging system of claim 10, wherein, The imaging system further includes: An array plate driving device arranged on the rack and connected with the blocking array plate and the correction device respectively; The array plate driving device is configured to drive the blocking array plate to rotate under the control of the correction device.

14. A correction device, characterized in that The storage medium includes a computer program, and the computer program is configured to control the correction device to perform the scatter estimation method according to any one of claims 1 to 9 when the computer program is executed.

15. A storage medium, characterized by The storage medium includes a computer program, and the computer program is configured to control the correction device to perform the scatter estimation method according to any one of claims 1 to 9 when the computer program is executed.

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