A method and system for image reconstruction

Abstract

The embodiment of the application discloses an image reconstruction method. The image reconstruction method comprises the following steps: scanning at least one scanning layer of a scanning object based on a deflection position of a scanning source and a detector, and obtaining scanning data; determining a segmentation point of a corresponding imaging area of the at least one scanning layer on the detector; determining to-be-reconstructed data based on the scanning data and the segmentation point corresponding to the at least one scanning layer, wherein the to-be-reconstructed data is used for reconstructing an image; and wherein the deflection position satisfies that a reconstruction field of view before deflection is greater than a reconstruction field of view after deflection.

Description

TECHNICAL FIELD

[0001] The present specification relates to the field of medical imaging, and in particular, to a method and system for medical image reconstruction. BACKGROUND

[0002] Medical imaging devices have become indispensable devices in the existing medical field. Image reconstruction is a key technology applied in the field of medical imaging. More specifically, a medical imaging device (e.g., a computed tomography (CT) device) scans a patient and reconstructs based on the scanned data. The mechanical deviation of a component (e.g., a mechanical arm) in the medical imaging device during the scanning process may cause artifacts in the reconstructed image, affecting the quality of the reconstructed image.

[0003] Therefore, it is necessary to propose an image reconstruction method of a medical imaging device to reduce the impact of artifacts on the quality of the reconstructed image, thereby improving the efficiency and accuracy of medical analysis and / or diagnosis. SUMMARY

[0004] One of the embodiments of the present specification provides an image reconstruction method. The image reconstruction method comprises: scanning at least one scanning layer of a scanning object based on a deflection position of a scanning source and a detector to obtain scanning data; determining a segmentation point of an imaging area corresponding to the at least one scanning layer on the detector, respectively; and determining to-be-reconstructed data based on the scanning data and the segmentation points corresponding to the at least one scanning layer, respectively, the to-be-reconstructed data being used for reconstructing an image; wherein the deflection position satisfies that a reconstruction field of view before deflection is greater than a reconstruction field of view after deflection.

[0005] One of the embodiments of the present specification provides an image reconstruction system. The system comprises: an acquisition module configured to scan at least one scanning layer of a scanning object based on a deflection position of a scanning source and a detector to obtain scanning data; a determination module configured to determine a segmentation point of an imaging area corresponding to the at least one scanning layer on the detector, respectively, and to determine to-be-reconstructed data based on the scanning data and the segmentation points corresponding to the at least one scanning layer, respectively, the to-be-reconstructed data being used for reconstructing an image; wherein the deflection position satisfies that a reconstruction field of view before deflection is greater than a reconstruction field of view after deflection.

[0006] One of the embodiments of the present specification provides an image reconstruction device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method of image reconstruction when executing the computer program.

[0007] One of the embodiments of the present specification provides a computer readable storage medium, the storage medium stores computer instructions, when the computer reads the computer instructions in the storage medium, the computer executes an image reconstruction method. BRIEF DESCRIPTION OF DRAWINGS

[0008] The present specification will be further described in the manner of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same numbers refer to the same structures or operations, in which:

[0009] Figure 1 is a schematic diagram of an application scenario of an image reconstruction system according to some embodiments of the present specification;

[0010] Figure 2 is an exemplary block diagram of an image reconstruction system according to some embodiments of the present specification;

[0011] Figure 3 is an exemplary flowchart of an image reconstruction method according to some embodiments of the present specification;

[0012] Figure 4 is an exemplary flowchart of determining to-be-reconstructed data according to some embodiments of the present specification;

[0013] Figure 5 is an exemplary schematic diagram of scanning based on a deflection position according to some embodiments of the present specification;

[0014] Figure 6 is an exemplary schematic diagram of determining a mapping matrix according to some embodiments of the present specification;

[0015] Figure 7 is an exemplary schematic diagram of fitting to determine a split point according to some embodiments of the present specification. DETAILED DESCRIPTION

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present specification, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some examples or embodiments of the present specification, and for those skilled in the art, without paying creative labor, the present specification can also be applied to other similar scenarios according to these drawings. Unless it is obvious from the language environment or otherwise stated, the same numbers in the drawings represent the same structure or operation.

[0017] It should be understood that the use of “system,” “device,” “unit,” and / or “module” herein is only meant to be a method of distinguishing different components, elements, and / or parts from one another. If other words are used instead of these terms, the meaning of the specification should not be limited to the words used in this specification.

[0018] As indicated in the specification and claims, unless the context clearly indicates otherwise, the words “a,” “an,” “the,” and / or “said” are not limited to the singular, but rather include plural, unless the context clearly indicates otherwise. Generally, the terms “comprises,” “comprising,” “includes,” “including,” and the like specify the presence of stated steps and elements but do not preclude the presence or addition of one or more other steps or elements.

[0019] Flowcharts are used in the specification to illustrate the operations of systems in accordance with embodiments of the specification. It should be understood that the preceding or following operations are not necessarily performed in the exact order shown. Rather, various steps can be handled in reverse order, or simultaneously. Other operations can also be added to, or removed from, these processes.

[0020] Figure 1 is a schematic diagram of an application scenario of an image reconstruction system according to some embodiments of the specification.

[0021] As Figure 1 indicated, the image reconstruction system 100 can include a processing device 110, a network 120, a user terminal 130, a storage device 140, and a medical imaging device 150.

[0022] In some embodiments, the image reconstruction system 100 can implement reconstruction of medical images by implementing the methods and / or processes disclosed in the specification.

[0023] The processing device 110 can process data and / or information obtained from the user terminal 130, the medical imaging device 150, and / or the storage device 140. The processing device 110 can access information and / or data through the network 120 or directly from the user terminal 130, the storage device 140, and / or the medical imaging device 150. For example, the processing device 110 can obtain scanning data of the medical imaging device 150 from the user terminal 130 and / or the medical imaging device 150. The processing device 110 can process the obtained data and / or information. For example, the processing device 110 can process the obtained scanning data to determine data to be reconstructed, and further reconstruct an image. In some embodiments, the processing device 110 can be a single server or a group of servers. The processing device 110 can be disposed in the medical imaging device 150. The processing device 110 can be local, remote, or implemented on a cloud platform.

[0024] The network 120 can include any suitable network that provides for the exchange of information and / or data that can facilitate the image reconstruction system 100. In some embodiments, one or more components of the image reconstruction system 100 (e.g., the processing device 110, the user terminal 130, the storage device 140, and the medical imaging device 150) can exchange information and / or data via the network 120. The network 120 can include a local area network (LAN), a wide area network (WAN), a wired network, a wireless network, etc., or any combination thereof.

[0025] The user terminal 130 refers to one or more terminal devices or software used by a user. In some embodiments, the user terminal 130 can be a mobile device, a tablet computer, etc., or any combination thereof. In some embodiments, the user terminal 130 can interact with other components in the image reconstruction system 100 via the network 120. For example, the user terminal 130 can send one or more control instructions to the medical imaging device 150 to control the processing device 110 to process the scan data of the medical imaging device 150 to determine the data to be reconstructed. In some embodiments, the user terminal 130 can be a part of the processing device 110. In some embodiments, the user terminal 130 can be integrated with the processing device 110 as an operating console of the medical imaging device 150.

[0026] The storage device 140 can be used to store data, instructions, and / or any other information. In some embodiments, the storage device 140 can store data and / or information obtained from, for example, the processing device 110, the user terminal 130, the medical imaging device 150, etc. For example, the storage device 140 can store the scan data, the data to be reconstructed, etc. The storage device 140 can be disposed in the medical imaging device 150. In some embodiments, the storage device 140 can include a mass storage, a removable storage, etc., or any combination thereof.

[0027] The medical imaging device 150 can be used to obtain scan data of a scan object. The scan object can include a biological object (e.g., a human body, an animal, etc.), a non-biological object (e.g., a phantom), etc. In some embodiments, the medical imaging device 150 can include a scan source and a detector (not shown). The scan source can be used to emit a radiation beam (e.g., an X-ray) onto the scan object. The detector can be used to receive the radiation beam to form the scan data. More details about the scan source and the detector can be found in step 310. In some embodiments, the medical imaging device 150 can be a CT imaging device, a PET-CT imaging device, etc. In some embodiments, the processing device 110 and the storage device 140 can be a part of the medical imaging device 150.

[0028] Figure 2Fig. 2 shows a block diagram of an image reconstruction system according to some embodiments of the present application. As shown in Fig. 2, the block diagram 200 of the image reconstruction system can include an obtaining module 210 and a determining module 220. Figure 2 As shown in Fig. 2, the block diagram 200 of the image reconstruction system can include an obtaining module 210 and a determining module 220.

[0029] The obtaining module 210 can be configured to obtain scan data by scanning at least one scan layer of a scan object based on a deflection position at which a scan source and a detector are located.

[0030] The determining module 220 can be configured to determine a split point of the at least one scan layer corresponding to an imaging region on the detector, and determine to-be-reconstructed data based on the scan data and the split point corresponding to the at least one scan layer, the to-be-reconstructed data being used for reconstructing an image.

[0031] In some embodiments, for each of the at least one scan layer, the determining module 220 can be configured to determine the scan data between the split point corresponding to the scan layer and a first end point of the imaging region corresponding to the scan layer as the to-be-reconstructed data, wherein the first end point is determined based on a deflection direction.

[0032] In some embodiments, for each of the at least one scan layer, the determining module 220 can be configured to determine a mapping point of a rotation center point of the scan layer in the imaging region as the split point.

[0033] In some embodiments, the at least one scan layer includes a first scan layer and a second scan layer, and the determining module 220 can be further configured to fit the split points corresponding to the at least two first scan layers respectively to determine the split point corresponding to the second scan layer.

[0034] For more information about the obtaining module 210 and the determining module 220, see Figures 3-6 and the related descriptions.

[0035] It should be understood that Figure 2 The system and its modules shown can be implemented in various ways. For example, in some embodiments, the system and its modules can be implemented by hardware, software, or a combination of software and hardware.

[0036] It should be noted that the above description of the candidate display, the determining system and its modules is for the convenience of description, and cannot limit the scope of the embodiments. It can be understood that, for those skilled in the art, after understanding the principle of the system, any combination of the modules or connection of the modules to other modules can be made without departing from the principle. In some embodiments, Figure 2The acquisition module 210 and determination module 220 disclosed herein can be different modules within a system, or a single module can implement the functions of two or more of the aforementioned modules. For example, modules can share a single storage module, or each module can have its own separate storage module. Such variations are all within the scope of protection of this specification.

[0037] Figure 3 This is an exemplary flowchart of an image reconstruction method according to some embodiments of this specification. Figure 3 As shown, process 300 includes the following steps. In some embodiments, process 300 may be executed by a processor (e.g., processing device 110).

[0038] Step 310: Based on the deflection positions of the scanning source and the detector, at least one scanning layer of the scanning object is scanned to acquire scanning data. In some embodiments, step 310 may be performed by the acquisition module 210.

[0039] like Figure 1 The scanned object refers to the object being scanned, which may include biological objects (e.g., human body, animal, etc.) and non-biological objects (e.g., phantom).

[0040] A scanning source can refer to a component in medical imaging equipment that emits a beam of radiation onto the object being scanned. For example, components of a scanning source include an X-ray tube that emits a beam of radiation (e.g., X-rays) to irradiate the target phantom. The location of the scanning source can be indicated by its focal point, which can be the focal point of the X-ray tube.

[0041] A detector can refer to a component in medical imaging equipment that receives the radiation beam passing through the object being scanned. The area of ​​the detector that receives the radiation beam can be considered its imaging area. During the scanning process, for each scan layer, the detector has a corresponding imaging area to receive the signal passing through that scan layer. In other words, the imaging area corresponding to the scan layer is the location on the detector that receives the signal from the scanning source when scanning that layer.

[0042] The deflection position refers to the position where the scanning source and detector are deflected relative to their original position. The original position is the position of the scanning source and detector before the deflection. In some embodiments, scanning the original position by the scanning source and detector within a specific angular range (e.g., 360°) yields a reconstructed field of view (hereinafter referred to as the reconstructed field of view before deflection) and corresponding scan data. Scanning the deflected position by the scanning source and detector within a specific angular range yields another reconstructed field of view (hereinafter referred to as the reconstructed field of view after deflection) and corresponding scan data. The reconstructed field of view can be the largest circular area centered on the center of interest of the scanned object, which can be covered by the scanning source rotating within a specific angular range (e.g., 360°) by the medical imaging device.

[0043] The deflection position satisfies the condition that the reconstructed field of view before deflection is greater than the reconstructed field of view after deflection. For example, ... Figure 5 As shown, circular region 502 represents the reconstructed field of view of the medical imaging device after a 360° rotation, before the scanning source and detector are deflected (i.e., in their original position). Circular region 503 represents the reconstructed field of view of the medical imaging device after a 360° rotation, after the scanning source and detector are deflected (i.e., in their deflected position). It can be seen that circular region 503 is larger than circular region 502. In some embodiments, the original position satisfies that the perpendicular line from the focal point of the scanning source to the detector passes through the rotation center. In the deflected position, the scanning source and detector can satisfy the condition that the perpendicular line from the focal point of the scanning source to the detector does not pass through the rotation center. In some embodiments, the scanning source and detector can expand the reconstructed field of view through deflection, i.e., the reconstructed field of view after deflection is larger than the reconstructed field of view before deflection. Overlapping areas may appear in the reconstructed field of view after deflection, i.e., the scan data corresponding to the reconstructed field of view may also include scan data from the overlapping areas. In some embodiments, by processing the scan data corresponding to the reconstructed field of view after deflection (e.g., removing redundant data from the overlapping areas), the data to be reconstructed can be determined; details can be found in step 320.

[0044] The rotation center can be the center around which the scanning source and detector rotate (e.g., 360°) during the scanning of the object. For example, the rotation center can be a line around which the scanning source and detector rotate to scan. The rotation center can be obtained from medical imaging equipment. The fact that the perpendicular line from the scanning source's focal point to the detector does not pass through the rotation center means that the perpendicular line does not intersect the rotation center.

[0045] In some embodiments, the deflection positions can be determined according to movements of the scan source and the detector, which can include rotation or translation. The rotation can be performed around a preset point by the scan source and the detector. For example, the detector and the scan source rotate around a point or a line (e.g., a center point or a center line) on the detector. It should be noted that the rotation for generating the deflection positions is different from the rotation for scanning the scan object to generate the scan data. The translation can be performed in a certain direction by at least one of the scan source and the detector. For example, the position of the scan source is fixed, and the position of the detector is translated, where the distance of the translation cannot exceed 1 / 2 of the length of the detector. For another example, the scan source and the detector can be simultaneously translated, and the moving directions of the scan source and the detector can be the same or opposite. When the moving directions of the scan source and the detector are the same, there is a relative displacement.

[0046] In some embodiments, the scan source and the detector can scan the scan object at the deflection positions. For example, the scan source and the detector rotate 360° at the deflection positions to scan the scan object to obtain the scan data.

[0047] The scan layer can refer to a plurality of layered regions of the scan object divided at a certain interval in a direction. The scan layer can have a certain layer thickness. In some embodiments, the scan layer can be divided according to actual conditions. For example, the scan layer can be divided according to characteristic parameters (such as age, weight, body features, diseases, etc.) of the scan object.

[0048] The scan data can refer to original data obtained by the medical imaging device when scanning the scan object. In some embodiments, after the medical imaging device emits a radiation beam to the scan object by using the scan source, the medical imaging device receives the radiation beam by using the detector to form the scan data. As described above, during the scanning process, the medical imaging device rotates by a certain angle to scan the scan object to obtain corresponding scan data, which corresponds to a reconstruction field of view. In some embodiments, the acquisition module 210 can acquire the scan data from the medical imaging device. In some embodiments, the acquisition module 210 can also acquire the scan data from a storage (e.g., the storage device 140).

[0049] In step 320, the to-be-reconstructed data used for reconstructing the image is determined based on the scan data. In some embodiments, step 320 can be performed by the determination module 220.

[0050] The to-be-reconstructed data refers to data obtained by processing the scan data and used for reconstructing the image.

[0051] In some embodiments, the determination module 220 can process noise (e.g., overlap, missing, error, anomaly, etc.) in the scan data to determine the to-be-reconstructed data.

[0052] In some embodiments, the determining module 220 can weight the scan data of the overlap region so that the weight of the scan data of the overlap region is consistent with the weight of the scan data of the non-overlap region, and determine the data to be reconstructed.

[0053] The non-overlap region is a region formed by positions in a scan layer of a scan object at which data is collected only once in a 360° rotation scan of the scan layer. The overlap region is a region formed by positions in the scan layer at which data is collected more than once (e.g., twice) in the 360° rotation scan of the scan layer. Accordingly, the scan data obtained by the scan includes scan data collected more than once (e.g., twice) at the same position, i.e., there is redundant scan data (e.g., the scan data of one of the two times of scan can be regarded as redundant scan data). If the image reconstruction is directly based on the scan data collected more than once, due to the inconsistency of the overlap region caused by mechanical deviation, artifacts can occur in the reconstructed image. The scan layer has a corresponding imaging region, and accordingly, the overlap region and the non-overlap region on the scan layer have corresponding regions on the imaging region.

[0054] In some embodiments, the scan data collected more than once in the overlap region can be weighted so that the weight of the scan data of the final overlap region is consistent with the weight of the scan data of the non-overlap region (e.g., the weight is 1), and the scan data of the overlap region and the scan data of the non-overlap region after the weighting are used as the data to be reconstructed. For example, the weight of the scan data of the non-overlap region is set to 1, and if the overlap region is scanned twice, the scan data of the two scans is weighted so that the weight of the scan data of the two scans is added to 1.

[0055] In some embodiments, for each of the at least one scan layer, the determining module 220 can determine the segmentation point of the corresponding imaging region of the scan layer on the detector, and determine the data to be reconstructed based on the scan data and the segmentation point corresponding to the scan layer. For example, the scan data between the segmentation point and the first end point in the imaging region corresponding to the scan layer is determined as the data to be reconstructed for the image reconstruction. For more details about determining the data to be reconstructed based on the segmentation point and the first end point, see Figure 4 .

[0056] For more details about the deflection position, the imaging region, the scan source, the overlap region, etc., see Figure 5 and the related description.

[0057] The scanning object can be scanned at each deflection position of the scanning source and the detector, so as to expand the scanning area and realize omnidirectional scanning of the scanning object. Meanwhile, due to mechanical deviation of components (such as a mechanical arm) in the medical imaging device, artifacts (i.e., overlapping areas) can be generated in the reconstructed image. By processing the scanning data of the overlapping areas, the influence of redundant data on the to-be-reconstructed data used for image reconstruction is avoided, the generation of artifacts is reduced, and the quality of the reconstructed image is improved.

[0058] Figure 4 An example flowchart for determining the to-be-reconstructed data is shown according to some embodiments of the present specification. In some embodiments, the flowchart 400 can be executed by a processor (for example, the processing device 110).

[0059] At step 410, for each of the at least one scanning layer, a split point of a corresponding imaging area of the scanning layer on the detector is determined. In some embodiments, the step 410 can be executed by the determining module 220.

[0060] As described above, the imaging area is an area on the detector that receives the radiation beam that passes through the scanning layer. Each scanning layer can correspond to an imaging area on the detector.

[0061] The split point can be a demarcation point that divides the imaging area into two parts. In some embodiments, the split point is located in an area (which can be referred to as an “overlapping corresponding area”) of the imaging area corresponding to the overlapping area. For example, the split point can be the midpoint of the overlapping corresponding area. The overlapping corresponding area receives different times of scanning data of the same position in the scanning layer at different positions. The split point divides the overlapping corresponding area, so that only single-time scanning data is used when the final reconstructed image is reconstructed.

[0062] In some embodiments, the determining module 220 can determine the split point of the corresponding imaging area of the scanning layer on the detector according to the deflection position. For example, the determining module 220 can obtain a corresponding preset value according to the related information of the deflection position (for example, the deflection mode, the deflection angle, etc.), so as to determine the position of the split point. The preset value is the distance between the split point and a certain endpoint of the imaging area. For example, there can be a corresponding relationship between different deflection modes and deflection parameters (such as the deflection angle) and the preset value. Based on the deflection mode and the deflection parameter, the corresponding preset value can be determined, and accordingly, the position of the split point can be determined.

[0063] In some embodiments, the determining module 220 can determine the mapping point of the rotation center point of the scanning layer in the imaging area as the split point, wherein the rotation center point can be determined based on the rotation center.

[0064] The rotation center point can be a point around which the scan source and the detector rotate in the scan layer, and each scan layer has a rotation center point.

[0065] The rotation center point can be determined based on the rotation center. In some embodiments, the intersection of the scan layer and the line on which the rotation center is located is the rotation center point. The rotation center point is derived from the rotation center. For example, the rotation center is a line, and the rotation center points of different scan layers are different points on the line. In some embodiments, the rotation center point can be obtained from the medical imaging device.

[0066] The mapping point can be a corresponding point in the imaging area determined by the rotation center point based on the mapping transformation. For example, the mapping transformation can be a transformation from three dimensions to two dimensions. In some embodiments, the mapping point can be the projection point of the rotation center point in the imaging area. In some embodiments, the mapping point can be the point in the imaging area corresponding to the focal point of the scan source and the rotation center point. For example, the mapping point is the intersection of the line on which the focal point of the scan source and the rotation center point are located and the imaging area.

[0067] In some embodiments, the mapping point can be determined based on the mapping matrix by processing the rotation center point. For example, the position coordinates of the mapping point can be obtained by formula (1):

[0068]

[0069] where P is the mapping matrix, (x i , y i , z i ) is the position coordinates of the rotation center point of the scan layer, (u i , v i ) is the position coordinates of the mapping point in the imaging area, w i is a coefficient, and i represents the i-th scan layer.

[0070] The mapping matrix can be obtained in various ways. For example, the mapping matrix can be determined by scanning the calibration phantom. In some embodiments, the mapping matrix is a projection matrix, that is, the mapping matrix is a matrix that converts the rotation center point in three-dimensional coordinates into the projection point of the rotation center point in the imaging area of the detector in two-dimensional coordinates. For obtaining the mapping matrix, please refer to Figure 6 and related descriptions.

[0071] In some embodiments, the determination module can determine the corresponding segmentation point by mapping calculation on the rotation center point of each scan layer.

[0072] In some embodiments, the determination module 220 can determine the segmentation points of other scan layers according to the segmentation points of some of the scan layers.

[0073] In some embodiments, at least one scanning layer includes a first scanning layer and a second scanning layer. The determining module 220 can fit the segmentation points corresponding to at least two first scanning layers respectively to determine the segmentation points corresponding to the second scanning layer.

[0074] The coordinates of the segmentation points corresponding to the first scan layer are known. The second scan layer can be a scan layer whose coordinates of the segmentation points need to be determined. For example, the coordinates of the segmentation points corresponding to the first scan layer can be calculated using the above equation (1). In some embodiments, at least two first scan layers can be the first and last scan layers among all scan layers, or the middle two or more scan layers among all scan layers. The second scan layer can be any scan layer other than the first scan layer among all scan layers.

[0075] In some embodiments, fitting using the coordinates of the segmentation points can include linear fitting and curve fitting. A linear fitting algorithm or a curve fitting algorithm can be used to fit at least two segmentation points corresponding to the first scan layer to obtain a fitted line (fitted straight line or fitted curve).

[0076] Line fitting algorithms include least squares, gradient descent, and Ley-Marx algorithm, while curve fitting algorithms include polynomial fitting algorithms. In some embodiments, fitting the segmentation points corresponding to at least two first scan layers using a line or curve fitting algorithm can be done by fitting the segmentation points corresponding to the first and last scan layers in all scan layers, or by fitting the segmentation points corresponding to the middle two or more scan layers in all scan layers.

[0077] In some embodiments, the determining module 220 can determine the segmentation point of the second scanning layer based on the determined fitted line. For example, the intersection of the fitted line and the imaging region corresponding to the second scanning layer can be used as the segmentation point of the second scanning layer.

[0078] For example, such as Figure 7 As shown, square HKVJ is a planar schematic diagram of the detector. The determination module 220 can determine the segmentation points corresponding to the first and last scan layers in all scan layers. The segmentation point corresponding to the first scan layer is M1, and the segmentation point corresponding to the last scan layer is M2. Then, the first and second scan layers are fitted together, for example, by directly connecting the segmentation points M1 and M2 corresponding to the first scan layer, resulting in a fitted line segment M1M2. The points on this line segment M1M2 include the segmentation points corresponding to all scan layers. The first endpoint of the imaging region corresponding to all scan layers is located on line segment VJ. The scan data corresponding to the polygonal region HKM1M2 is considered redundant data; the polygonal region M1M2VJ is used for image reconstruction.

[0079] In some embodiments, the determining module 220 can also fit the segmentation point corresponding to the at least two first scan layers with a machine learning model (may be referred to as a “fitting model”). For example, the input of the fitting model is the coordinate position of the segmentation point of the at least two first scan layers, and the output is the coordinate position of the segmentation point of the second scan layer.

[0080] At step 420, the scan data between the segmentation point corresponding to the scan layer and the first end point of the imaging region corresponding to the scan layer is determined as the to-be-reconstructed data. In some embodiments, step 420 can be performed by the determining module 220.

[0081] In some embodiments, for each of the at least one scan layer, the imaging region corresponding to the scan layer includes two end points, i.e., includes a first end point and a second end point. The first end point and the second end point can be points of the range of signals generated by the detector when receiving the radiation beam to scan the scan layer, i.e., the first end point and the second end point determine the range of imaging.

[0082] In some embodiments, the first end point is determined based on the deflection direction. In some embodiments, the first end point is the point close to the deflection direction. For example, for the case of rotation deflection, if the deflection direction is counterclockwise, the first end point is the end point on the left side of the imaging region. If the deflection direction is clockwise, the first end point is the end point on the right side of the imaging region. For example, for the case of translation deflection, if the deflection direction is right translation, the first end point is the end point on the right side of the imaging region. If the deflection direction is left translation, the first end point is the end point on the left side of the imaging region. For example, as shown in FIG. 5, the rotation direction 504 is counterclockwise, and the Q point is the first end point. It can be understood that the second end point is another end point in the imaging region except the first end point. Figure 5

[0083] In some embodiments, the distance between the first end point and the segmentation point is not less than the distance between the second end point and the segmentation point. In some embodiments, the first end point and the second end point can be determined according to the distances between the two end points of the imaging region and the segmentation point.

[0084] In some embodiments, the scan data between the segmentation point and the first end point of the imaging region is the to-be-reconstructed data, and the scan data between the segmentation point and the second end point of the imaging region is the overlapping data, i.e., the to-be-reconstructed data does not include the scan data between the second end point of the imaging region and the segmentation point.

[0085] In some embodiments, during image reconstruction, only the scan data between the segmentation point and the first end point is used for reconstruction.

[0086] For more details about the first end point, the second end point, the rotation center point, and the segmentation point, please refer to Figure 4 and the related descriptions thereof.

[0087] ​By determining the segmentation points, redundant data can be accurately removed, reducing artifacts in the reconstructed image. Furthermore, segmentation points can be determined for each individual reconstructed image, avoiding the problem of inconsistent overlap lengths in each projection due to mechanical deviations during the rotational scanning process of the gantry (e.g., scanning source and detector), which could lead to inaccurate determination of the overlap area and poor reconstructed image quality.

[0088] Figure 5 This is an exemplary schematic diagram illustrating scanning based on deflection position according to some embodiments of this specification.

[0089] Figure 5 The image shows the scanning source and detector scanning a layer of the object on the Y-axis (not shown in the image). Figure 5 (As shown) is a cross-section, where the Y-axis is a line perpendicular to the plane formed by the detector and the scanning source, and the plane containing the X and Z axes is the plane formed by the focal point of the scanning source and the imaging area of ​​the scanning layer on the detector. The X-axis is a line determined based on the imaging area on the detector when the scanning source and detector are in their original positions, and the Z-axis is a line perpendicular to the focal point of the scanning source and the imaging area when the scanning source and detector are in their original positions.

[0090] O is the rotation center point of the scanning layer, T is the position of the focal point of the scanning source before deflection (i.e., the position of the focal point of the scanning source in the original position), D is the midpoint of the imaging region, and AB is the imaging region corresponding to the scanning layer before deflection (i.e., the position of the imaging region corresponding to the scanning layer in the original position).

[0091] The scanning source and detector can rotate around the center of the detector (i.e., the imaging area AB can rotate around its midpoint D). The focal point of the scanning source rotates from the original position T to the deflection position T', and the imaging area of ​​the detector rotates from the original position AB to the deflection position QP.

[0092] T' represents the position after deflection (i.e., the focal point of the scanning source at the deflection position), and QP represents the imaging area corresponding to the scanning layer after deflection (i.e., the imaging area corresponding to the scanning layer at the deflection position). Circular region 502 (i.e....) Figure 5 The un-thickened solid circle in the image represents the reconstructed field of view before the scanning source and detector are deflected (i.e., in their original position), and after the medical imaging equipment has rotated 360°. Circular region 503 (i.e....) Figure 5 The bold solid circle in the image represents the reconstructed field of view after the scanning source and detector are deflected (i.e., the deflection position) and the medical imaging equipment is rotated 360°.

[0093] During a 360° rotation scan, the circular region 501 (i.e. Figure 5The circular region 501 is an overlapping region. For example, the position 501-1 is acquired twice, and the position 501-1 can be regarded as an overlapping position in the overlapping region. When the scanning source is above (i.e., in the positive direction of the Z axis), the position 501-1 is acquired once, and the data acquired in this acquisition is received by a certain position in the region of NMs in the imaging region. When the scanning source is below (i.e., in the negative direction of the Z axis), the position 501-1 is acquired once, and the data acquired in this acquisition is received by a certain position in the region of MPs in the imaging region. One of the twice-acquired data can be regarded as redundant data. The other positions in the circular region 501 are similar, and are not described again. Accordingly, there is redundant data in the data acquired by the two regions of MPs and MNs in the imaging region.

[0094] The point M is the mapping point of the rotation center point of the scanning layer on the imaging region. M is the division point of the imaging region QP. The deflection direction 504 is deflected toward Q, which is the first end point, and P, which is the second end point. It can be seen that QM is greater than PM. The data received by QM in the imaging region is regarded as the to-be-reconstructed data, and the data received by MP is regarded as the redundant data.

[0095] Figure 6 FIG. 6 is an example schematic diagram of determining a mapping matrix according to some embodiments of the present specification.

[0096] As described above, the determination module 220 can determine the mapping matrix by scanning the calibration phantom. In some embodiments, the processing device scans the calibration phantom to obtain calibration scanning data, the calibration phantom comprising a preset point; performs image reconstruction based on the calibration scanning data to obtain a calibration image; obtains a first coordinate of the preset point in the calibration image; obtains a second coordinate of the preset point in the calibration phantom; and determines the mapping matrix based on the first coordinate and the second coordinate.

[0097] The calibration phantom can be a non-biological object. For example, a phantom, a mechanical model of various shapes, and the like. In some embodiments, the calibration phantom comprises one or more preset points. The preset point is a specific point (e.g., a center point, etc.) in a specific substance. The specific substance can be distinguished from other substances in the calibration phantom. For example, the specific substance is a ball, etc. In some embodiments, a three-dimensional coordinate system can be established to determine the first coordinate of the preset point. For example, by measuring, etc.

[0098] In some embodiments, the medical imaging device can scan the calibration phantom to obtain calibration scanning data. For example, based on the original position or the deflected position to perform a rotating scan, etc. Further, the scanning data is preprocessed or directly based on the scanning data to perform image reconstruction to obtain a calibration image. For the preprocessing, see Figure 3and related descriptions. In some embodiments, a two-dimensional coordinate system can be established, and the second coordinates of the preset points in the calibration image can be determined. For example, by measuring or the like. It can be understood that because the specific position can be distinguished from other substances in the calibration phantom, the specific substance can be detected by reconstructing the image, and further, the second coordinates of the specific point of the specific substance can be determined.

[0099] In some embodiments, the processing device can determine a conversion matrix or a mapping matrix mapped from the first coordinates to the second coordinates based on the first coordinates and the second coordinates. For example, the processing device determines the mapping matrix based on the first coordinates and the second coordinates of the plurality of preset points. For example, the solving method can be Gauss projection or the like.

[0100] As shown in Figure 6 , the j-th scanning layer of the calibration phantom is scanned. The X, Y and Z axes are a three-dimensional coordinate system constructed based on the calibration phantom. The meanings of X, Y and Z are similar to Figure 5 , and will not be repeated here.

[0101] I is the calibration phantom, and K is a preset point in the calibration phantom, the first coordinate of which is (x j , y j , z j ), for example, the preset point is the midpoint of the specific substance in the calibration phantom. The preset point is located in the j-th scanning layer.

[0102] The two-dimensional coordinate system constructed by the U axis and the V axis is a mapping coordinate system, which is constructed based on the calibration image F.

[0103] K is the position of the preset point on the calibration image, and the first coordinate of the point is (u j , v j ).

[0104] T” is the focal point of the scanning source, and the position of T” can be the same as T’ and T, or different.

[0105] The above has described the basic concept, and it is obvious that the above detailed disclosure is only an example for the person skilled in the art, and does not constitute a limitation on the present specification. Although it is not explicitly stated here, the person skilled in the art can make various modifications, improvements and corrections to the present specification. Such modifications, improvements and corrections are suggested in the present specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present specification.

[0106] Also, the use of "a" or "an" or "the" or "at least one" or "one or more" or "one or more instances" throughout the specification try to convey a similar meaning as the term "one or more" unless the context clearly dictates otherwise. The terms "comprising," "including," "containing," and "having" are intended to be open-ended terms. Likewise, the term "comprises" is synonymous with "includes" or "containing," and the transitional phrases "comprising," "including," "containing," or "having" are not used to limit the scope of the claims to the complete recitation of elements or options that follow the transitional phrase or to specify a single or exclusive material. The use of "including" and "comprising" and variations thereof are intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof, unless otherwise noted or required by context. Unless otherwise noted, the use of the singular includes the plural. The use of "or" means "and / or," unless otherwise noted or required by context. The use of the term "based on" means "based, at least in part, on," unless otherwise noted or required by context.

[0107] In addition, the order of presentation of the processing elements and sequences described in this specification, unless otherwise indicated, is not intended to be construed as a limitation, but for an explanation of one or more embodiments. Furthermore, the use of numbering or letters in the description of elements, or the use of other designations, is not intended to limit the scope of the processes and methods disclosed in this specification. Although some presently preferred embodiments of the applications have been described above with particular emphasis on the advantages thereof, it will be understood to those of ordinary skill in the art that various changes in form and details can be made therein without departing from the spirit and scope of the applications. For example, although the system components described above can be implemented by hardware devices, they can also be implemented by software solutions only, such as installing the described system on an existing server or mobile device.

[0108] Similarly, it is to be noticed that the term "comprising", used in the description, is not intended to exclude other elements or steps. Nor does the term "comprising" indicate that the described elements or steps are essential or indispensable for the practice of the applications. In addition, it should be understood that elements, or steps, that have been described as being optional can be provided in some embodiments. Conversely, elements or steps that have been described as being essential or indispensable can be omitted in some embodiments.

[0109] In some embodiments, numbers describing compositions, quantities of attributes, are used. It is to be understood that such numbers used in the description of the embodiments are, in some examples, modified by the adjectives "about", "approximately", or "substantially". Unless otherwise indicated, "about", "approximately" or "substantially" mean that the number is allowed to vary by plus or minus 20%. Accordingly, numerical parameters in the specification and claims are approximations, which can vary depending on the requirements of the particular embodiment. In some embodiments, numerical parameters are approximations that can depend on the requirements of the particular embodiment. In some embodiments, numerical parameters should be considered in the context of the number of significant digits used for measurement of the quantity. Although the numerical ranges and parameters setting forth the broadest scope of the embodiments disclosed herein are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values set forth in the specific examples are provided to give a general understanding of the embodiments.

[0110] Each patent, patent application, patent publication, and other material cited in this specification is hereby incorporated by reference in its entirety herein for the teachings relevant to the sentence and / or paragraph in which the reference is presented. Document histories, to the extent not inconsistent with the pertinent U.S. patent application file history, are also incorporated by reference herein. To the extent that material incorporated by reference contradicts or contradicts any portion of this specification, including definition, the portion of the material incorporated by reference prevails. Note, however, that in the event of inconsistencies between any such material and the present specification, including definitions, the present specification, including definitions, will control.

[0111] Finally, it should be understood that the embodiments described herein are merely exemplary of the principles of the present description. Other embodiments can be devised without departing from the scope of the present description. Accordingly, the embodiments described herein are not intended to limit the scope of the present description, but rather are intended to be exemplary thereof.

Claims

1. A method of image reconstruction, characterized by, The method comprises: scanning at least one scanning layer of a scanning object based on a deflection position of a scanning source and a detector to obtain scanning data; determining a split point of the at least one scanning layer in a corresponding imaging area of the detector, the imaging area comprising two end points determining an imaging range; for each of the at least one scanning layer, determining one of the two end points as a first end point and the other of the two end points as a second end point based on a deflection direction; determining scanning data between the split point and the first end point as to-be-reconstructed data; determining scanning data between the split point and the second end point as overlapping data; reconstructing only based on the to-be-reconstructed data corresponding to the at least one scanning layer respectively to generate a reconstructed image; wherein the deflection position satisfies that a reconstruction field of view before deflection is greater than a reconstruction field of view after deflection.

2. The method of claim 1, wherein, The determination of the split point of the at least one scanning layer in the corresponding imaging area of the detector comprises: for one of the at least one scanning layer, determining a mapping point of a rotation center point of the scanning layer in the imaging area as the split point, the rotation center point being a point around which the scanning source and the detector rotate in the corresponding scanning layer.

3. The method of claim 1, wherein, The at least one scanning layer comprises a first scanning layer and a second scanning layer, and the determination of the split point of the at least one scanning layer in the corresponding imaging area of the detector comprises: fitting the split points corresponding to at least two first scanning layers respectively to determine a split point corresponding to the second scanning layer.

4. An image reconstruction system characterized by, The system comprises: an acquisition module configured to scan at least one scanning layer of a scanning object based on a deflection position of a scanning source and a detector to obtain scanning data, wherein the deflection position satisfies that a reconstruction field of view before deflection is greater than a reconstruction field of view after deflection; a determination module configured to determine a split point of the at least one scanning layer in a corresponding imaging area of the detector, the imaging area comprising two end points determining an imaging range; for each of the at least one scanning layer, determine one of the two end points as a first end point and the other of the two end points as a second end point based on a deflection direction; determine scanning data between the split point and the first end point as to-be-reconstructed data; determine scanning data between the split point and the second end point as overlapping data; and reconstruct only based on the to-be-reconstructed data corresponding to the at least one scanning layer respectively to generate a reconstructed image.

5. The system of claim 4, wherein, The determination module is further configured to: for one of the at least one scanning layer, determine a mapping point of a rotation center point of the scanning layer in the imaging area as the split point, the rotation center point being a point around which the scanning source and the detector rotate in the corresponding scanning layer.

6. The system of claim 4, wherein, The at least one scanning layer comprises a first scanning layer and a second scanning layer, and the determination module is further configured to: fit the split points corresponding to at least two first scanning layers respectively to determine a split point corresponding to the second scanning layer.

7. An image reconstruction device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the method of any one of claims 1-3 when executing the computer program.

8. A computer-readable storage medium storing computer instructions, wherein, The computer implements the method of any one of claims 1-3 when reading the computer instructions in the storage medium.

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