Method and device for automatically acquiring geometric errors of CBCT system

Abstract

The present disclosure provides a method for automatically acquiring geometric errors of a CBCT system, comprising: photographing an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple viewing angles; inferring the spatial position of the calibration object's center of mass based on the projection images from the multiple viewing angles and geometric parameters of the CBCT system; and acquiring a geometric error characteristic value of the CBCT system based on the inferred spatial position of the calibration object's center of mass and the projection positions of the center of mass in each of the projection images from the multiple viewing angles to indicate the geometric error of the CBCT system. The present disclosure also provides an apparatus for automatically acquiring geometric errors of a CBCT system and a CBCT system.

Description

Technical Field

[0001] The present disclosure relates to the field of CT technology, and in particular to a method for automatically acquiring geometric errors of a CBCT system, an apparatus for automatically acquiring geometric errors of a CBCT system, and a CBCT system. Background Art

[0002] Based on various reconstruction algorithms, CBCT equipment can generate three-dimensional images, greatly assisting in the diagnosis of various conditions. A fundamental aspect of these reconstruction algorithms is the correct geometric relationship between the radiation source, the rotation axis, and the detector.

[0003] Only with correct geometric relationships can accurate 3D images be reconstructed. Therefore, all CBCT devices require certain means to obtain the correct geometric relationships during installation and store them within the CBCT device. The pre-stored geometric relationships are then automatically used during the imaging process for image reconstruction.

[0004] However, since CBCT is a motion system, the detector and radiation source rotate around the rotation axis. If used for too long or too many times, slight movement may easily occur, resulting in inaccurate geometric relationships. Therefore, geometric artifacts can often be seen in the reconstructed image.

[0005] Geometric artifacts can affect image quality and distort imaging results. For example, geometric artifacts can blur or distort previously clear root canals. Artifacts can even cause doctors to misjudge tooth cracks. Doctors generally lack professional CT knowledge and only become aware of CT imaging issues after multiple images of patients exhibit severe geometric distortion. This makes it difficult for doctors to detect geometric issues promptly and they often fail to contact CT equipment manufacturers. Consequently, when geometric issues arise, the images they capture of patients are often flawed. Summary of the Invention

[0006] In order to solve at least one of the above technical problems, the present disclosure provides a method for automatically acquiring geometric errors of a CBCT system, an apparatus for automatically acquiring geometric errors of a CBCT system, and a CBCT system.

[0007] According to one aspect of the present disclosure, a method for automatically acquiring geometric errors of a CBCT system is provided, comprising:

[0008] A. photographing an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple viewing angles;

[0009] B. calculating the center of mass spatial position of the calibration object based on the projection images of the multiple shooting angles of the calibration object and the geometric parameters of the CBCT system;

[0010] C. Obtaining a geometric error characteristic value of the CBCT system based on the calculated spatial position of the center of mass of the calibration object and the projection position of the center of mass in each projection image of the multiple shooting angles to indicate the geometric error of the CBCT system.

[0011] According to at least one embodiment of the present disclosure, in the method for automatically acquiring the geometric error of a CBCT system, the number of the calibration objects is one or more than two. When the number of the calibration objects is more than two, an average value of geometric error characteristic values ​​obtained based on each of the calibration objects is taken to indicate the geometric error of the CBCT system.

[0012] According to at least one embodiment of the present disclosure, a method for automatically acquiring geometric errors of a CBCT system includes: A. photographing an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple photographing angles, including:

[0013] S102, photographing an imaging area including a calibration object disposed between a ray source and a detector to obtain projection images of three or more photographing viewing angles;

[0014] S104: Obtaining a projection position of the center of mass of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle.

[0015] According to at least one embodiment of the present disclosure, the method for automatically acquiring geometric errors of a CBCT system, B, inferring the spatial position of the center of mass of the calibration object based on the projection images of the multiple shooting angles of the calibration object and the geometric parameters of the CBCT system, includes:

[0016] S106: Generate a spatial pointing line / segment for each shooting angle based on the centroid projection position of the calibration object at each shooting angle, the spatial position of the ray source, and the spatial position of the detector, wherein the spatial pointing line / segment passes through the centroid projection position and the spatial position of the ray source;

[0017] S108. Obtain a perpendicular line segment between any two of the spatially pointing straight lines / line segments, use the midpoint of the perpendicular line segment as the estimated spatial center of mass position of the calibration object, and obtain the estimated average spatial center of mass position of the calibration object based on the obtained multiple estimated spatial center of mass positions of the calibration object.

[0018] According to at least one embodiment of the present disclosure, the method for automatically acquiring geometric errors of a CBCT system, C. acquiring a geometric error characteristic value of the CBCT system based on the calculated spatial position of the center of mass of the calibration object and the projection position of the center of mass in each projection image of the multiple shooting angles to indicate the geometric error of the CBCT system, includes:

[0019] S110 , obtaining the distances between the estimated average center of mass spatial position of the calibration object and each of the spatial pointing straight lines / line segments and generating an average distance of each of the distances to indicate a geometric error of the CBCT system.

[0020] According to at least one embodiment of the present disclosure, in the method for automatically acquiring the geometric error of a CBCT system, S110 is: obtaining the optimized spatial position of the center of mass of the calibration object based on the estimated average spatial position of the center of mass of the calibration object, obtaining the distance between the optimized spatial position of the center of mass of the calibration object and each of the spatially pointing straight lines / line segments, and generating an average distance of each of the distances to indicate the geometric error of the CBCT system.

[0021] According to at least one embodiment of the present disclosure, a method for automatically acquiring geometric errors of a CBCT system, obtaining an optimized center-of-mass spatial position of the calibration object based on an estimated average center-of-mass spatial position of the calibration object, includes:

[0022] The estimated average center of mass spatial position is optimized using an optimization algorithm / model to obtain the optimized center of mass spatial position of the calibration object.

[0023] According to at least one embodiment of the present disclosure, the method for automatically acquiring geometric errors of a CBCT system, C. acquiring a geometric error characteristic value of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each projection image of the multiple shooting angles to indicate the geometric error of the CBCT system, further includes:

[0024] S112: Compare the average distance with a preset threshold distance, and generate geometric error warning information when the average distance is greater than or equal to the preset threshold distance.

[0025] According to at least one embodiment of the present disclosure, in the method for automatically acquiring geometric errors of a CBCT system, in S108, obtaining an estimated average spatial position of the center of mass of the calibration object based on the acquired multiple estimated spatial positions of the center of mass of the calibration object includes:

[0026] An average of the multiple estimated center-of-mass spatial positions of the calibration object is taken to obtain the estimated average center-of-mass spatial position of the calibration object.

[0027] According to another aspect of the present disclosure, a device for automatically acquiring geometric errors of a CBCT system is provided, comprising:

[0028] A projection processing module, the projection processing module obtaining projection images of multiple shooting angles based on at least shooting an imaging area including a calibration object disposed between the ray source and the detector;

[0029] a centroid spatial position acquisition module, which calculates the centroid spatial position of the calibration object based on the projection images of the multiple shooting angles of the calibration object and the geometric parameters of the CBCT system;

[0030] A geometric error determination module is configured to obtain a geometric error characteristic value of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each projection image of the multiple shooting angles to indicate the geometric error of the CBCT system.

[0031] According to at least one embodiment of the present disclosure, the geometric error automatic acquisition device of the CBCT system, the projection processing module includes:

[0032] A centroid projection position acquisition module, which acquires the centroid projection position of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle;

[0033] A spatial pointing straight line / line segment acquisition module generates a spatial pointing straight line / line segment for each shooting angle based on the centroid projection position of the calibration object at each shooting angle, the spatial position of the ray source, and the spatial position of the detector. The spatial pointing straight line / line segment passes through the centroid projection position and the spatial position of the ray source.

[0034] According to at least one embodiment of the present disclosure, the geometric error automatic acquisition device of the CBCT system, the centroid spatial position acquisition module includes:

[0035] An estimated average center of mass spatial position acquisition module is configured to obtain a perpendicular line segment between any two of the spatially pointing straight lines / line segments, and use the midpoint of the perpendicular line segment as the estimated center of mass spatial position of the calibration object. The estimated average center of mass spatial position of the calibration object is obtained based on the multiple estimated center of mass spatial positions of the calibration object.

[0036] According to the apparatus for automatically acquiring geometric errors of a CBCT system of at least one embodiment of the present disclosure, the geometric error determination module obtains the distances between the estimated average spatial center of mass of the calibration object and each of the spatially pointing straight lines / line segments and generates an average distance of each of the distances to indicate the geometric error of the CBCT system.

[0037] According to the device for automatically acquiring geometric errors of a CBCT system of at least one embodiment of the present disclosure, the projection processing module further includes:

[0038] A projection image generation module is provided, wherein the projection image generation module obtains projection images of three or more shooting angles based on projection data of a calibration object disposed between a ray source and a detector.

[0039] According to the apparatus for automatically acquiring geometric errors of a CBCT system according to at least one embodiment of the present disclosure, the geometric error determination module further includes:

[0040] A warning information generation module is configured to compare the average distance with a preset threshold distance, and to generate geometric error warning information when the average distance is greater than or equal to the preset threshold distance.

[0041] According to another aspect of the present disclosure, a CBCT system is provided, comprising: a radiation source; a radiation detector; a calibration object disposed between the radiation source and the radiation detector; and the automatic geometric error acquisition device described in any one of the above items, the automatic geometric error acquisition device acquiring and / or outputting the geometric error of the CBCT system.

[0042] According to at least one embodiment of the present disclosure, the CBCT system further includes a holding device for stably holding the imaging part of the imaging object within the imaging field of view of the CBCT system, and the calibration object is disposed on the holding device. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0044] Figure 1 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to an embodiment of the present disclosure.

[0045] Figure 2 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.

[0046] Figure 3 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.

[0047] Figure 4 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.

[0048] Figure 5 FIG. 1 is a flow chart of a method S100 for automatically acquiring geometric errors of a CBCT system according to yet another embodiment of the present disclosure.

[0049] Figure 6 It is a schematic block diagram of the structure of a device for automatically acquiring geometric errors of a CBCT system using a hardware implementation of a processing system according to an embodiment of the present disclosure.

[0050] Figure 7 FIG1 is a schematic structural diagram (side view) of a CBCT system according to an embodiment of the present disclosure in which a calibration object is arranged on a holding device.

[0051] Description of Reference Numerals

[0052] 1000 Geometric Error Automatic Acquisition Device

[0053] 1002 Projection Image Generation Module

[0054] 1004 Centroid Projection Position Acquisition Module

[0055] 1006 Space pointing straight line / line segment acquisition module

[0056] 1008 Estimated mean center of mass spatial position

[0057] 1010 Geometric Error Determination Module

[0058] 1012 Warning information generation module

[0059] 1100 bus

[0060] 1200 processor

[0061] 1300 Memory

[0062] 1400 Other circuits. DETAILED DESCRIPTION

[0063] The present disclosure will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the relevant content and are not intended to limit the present disclosure. It should also be noted that, for ease of description, only the portions relevant to the present disclosure are shown in the accompanying drawings.

[0064] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present disclosure can be combined with each other. The technical solution of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0065] Unless otherwise stated, the exemplary embodiments / examples shown are to be understood as providing exemplary features of various details of some ways in which the technical concepts of the present disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / examples may be further combined, separated, interchanged, and / or rearranged without departing from the technical concepts of the present disclosure.

[0066] The use of cross hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise indicated, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the order described. In addition, the same figure numbers represent the same components.

[0067] When a component is referred to as being “on,” “over,” “connected to,” or “coupled to” another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another component, there are no intervening components present. For this purpose, the term “connected” may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0068] The terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, the features, integral bodies, steps, operations, parts, assemblies and / or their groups stated are indicated, but the presence or addition of one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups is not excluded. It should also be noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, and as such, they are used to explain the inherent deviations of the measured values, calculated values ​​and / or values ​​provided that will be recognized by those of ordinary skill in the art.

[0069] Combined with the following Figures 1 to 7 The method for automatically acquiring geometric errors of a CBCT system, the device for automatically acquiring geometric errors of a CBCT system, and the CBCT system disclosed in the present invention are described in detail.

[0070] Figure 1 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to an embodiment of the present disclosure.

[0071] like Figure 1 As shown, the method for automatically obtaining geometric errors of a CBCT system disclosed in the present invention includes:

[0072] A. photographing an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple viewing angles;

[0073] B. Calculate the center of mass spatial position of the calibration object based on projection images of multiple shooting angles of the calibration object and the geometric parameters of the CBCT system;

[0074] C. Obtaining a geometric error characteristic value of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each projection image of multiple shooting angles to indicate the geometric error of the CBCT system.

[0075] The number of calibration objects is one or more than two. When the number of calibration objects is more than two, an average value of geometric error characteristic values ​​obtained based on each calibration object is taken to indicate the geometric error of the CBCT system.

[0076] Figure 2 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.

[0077] refer to Figure 2The method S100 for automatically acquiring geometric errors of a CBCT system in this embodiment includes:

[0078] S102, photographing an imaging area including a calibration object disposed between a ray source and a detector to obtain projection images of three or more photographing viewing angles;

[0079] S104, obtaining a projection position of the centroid of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle;

[0080] S106: Generate a spatial pointing line / segment for each shooting angle based on the centroid projection position of the calibration object, the spatial position of the ray source, and the spatial position of the detector. The spatial pointing line / segment passes through the centroid projection position and the spatial position of the ray source.

[0081] S108: Obtain a perpendicular line segment between any two spatially pointing straight lines / line segments, use the midpoint of the perpendicular line segment as the estimated spatial position of the center of mass of the calibration object, and obtain an estimated average spatial position of the center of mass of the calibration object based on the obtained multiple estimated spatial positions of the center of mass of the calibration object;

[0082] S110 , obtaining the distances between the estimated average center of mass spatial position of the calibration object and each spatial pointing straight line / line segment and generating an average distance of each distance to indicate a geometric error of the CBCT system.

[0083] A CBCT system (i.e., cone-beam CT system) includes a radiation source and a radiation detector, typically an X-ray source and an X-ray detector. The CBCT system can be used to capture anteroposterior and lateral views of the imaging part of the imaging object, and can also synchronously drive the radiation source and radiation detector to rotate to obtain a CT image (three-dimensional image) of the imaging part.

[0084] Using the geometric parameters of existing CBCT systems, the spatial positions of the X-ray source and detector at certain viewing angles can be determined. Furthermore, the actual coordinates (i.e., spatial coordinates) of the projection of a calibration object (e.g., a steel ball) can be directly inferred based on the image position (pixel coordinates) of the projection image. Consequently, for any viewing angle that captures the steel ball, a line or segment in space can be derived, pointing from the X-ray source to the calibration object's projection image. This operation is repeated for each viewing angle that captures the steel ball, resulting in a series of lines or segments in space.

[0085] Ideally, these straight lines / line segments must intersect at one point, which is the actual spatial coordinate of the calibration object. However, due to the existence of errors, these straight lines cannot intersect at one point even if the geometric parameters have just been calibrated.

[0086] Among them, the acquisition of geometric parameters can be carried out through the method disclosed in Chinese patent application 2021105915312 (Geometric parameter acquisition method and acquisition system of cone beam CT system), which will not be repeated here.

[0087] In the present disclosure, the calibration object is preferably a spherical calibration object, and the material is preferably a steel ball or other metal sphere. Those skilled in the art can adjust the size of the calibration object based on the indication accuracy of the geometric error.

[0088] In step S110 of this embodiment, the geometric error of the CBCT system is indicated by calibrating the average distance between the estimated average center of mass spatial position of the object and each spatially pointing straight line / line segment.

[0089] Figure 3 FIG. 4 is a flow chart of a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.

[0090] like Figure 3 As shown, the method S100 for automatically acquiring geometric errors of a CBCT system in this embodiment includes:

[0091] S102, photographing an imaging area including a calibration object disposed between a ray source and a detector to obtain projection images of three or more photographing viewing angles;

[0092] S104, obtaining a projection position of the centroid of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle;

[0093] S106: Generate a spatial pointing line / segment for each shooting angle based on the centroid projection position of the calibration object, the spatial position of the ray source, and the spatial position of the detector. The spatial pointing line / segment passes through the centroid projection position and the spatial position of the ray source.

[0094] S108: Obtain a perpendicular line segment between any two spatially pointing straight lines / line segments, use the midpoint of the perpendicular line segment as the estimated spatial position of the center of mass of the calibration object, and obtain an estimated average spatial position of the center of mass of the calibration object based on the obtained multiple estimated spatial positions of the center of mass of the calibration object;

[0095] S110. Obtaining an optimized center of mass spatial position of the calibration object based on the estimated average center of mass spatial position of the calibration object, obtaining the distances between the optimized center of mass spatial position of the calibration object and each spatial pointing straight line / line segment, and generating an average distance of each distance to indicate a geometric error of the CBCT system.

[0096] In step S110 of this embodiment, the geometric error of the CBCT system is indicated by calibrating the average distance between the optimized centroid spatial position of the object and each spatially pointing straight line / line segment.

[0097] For the method S100 for automatically acquiring geometric errors of the CBCT system in each of the above embodiments, preferably, obtaining the optimized center-of-mass spatial position of the calibration object based on the estimated average center-of-mass spatial position of the calibration object includes:

[0098] The estimated average center of mass spatial position is optimized using an optimization algorithm / model to obtain the optimized center of mass spatial position of the calibration object.

[0099] According to a preferred embodiment of the present disclosure, the spatial position of the center of mass of the calibrated object is used as the parameter to be optimized of the optimization algorithm / model, the sum of the distances between the estimated average spatial position of the center of mass of the calibrated object and each spatially pointing straight line / line segment is used as the objective function of the optimization algorithm / model, and the estimated average spatial position of the center of mass of the calibrated object is used as the initial parameter of the optimization algorithm / model. The local minimum value of the objective function can be obtained, thereby obtaining the optimized spatial position of the center of mass of the calibrated object (obtaining the parameter to be optimized).

[0100] The optimization algorithm / model may use the Nelder-Mead algorithm.

[0101] The method S100 for automatically acquiring geometric errors of a CBCT system in each of the above embodiments preferably further includes:

[0102] S112: Compare the average distance with a preset threshold distance, and generate a geometric error warning message when the average distance is greater than or equal to the preset threshold distance.

[0103] Figure 4 FIG. 1 is a flow chart of a method S100 for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure. Figure 5 FIG. 1 is a flow chart of a method S100 for automatically acquiring geometric errors of a CBCT system according to yet another embodiment of the present disclosure.

[0104] The automatic acquisition method of geometric errors disclosed in the present invention uses the average value of the distance between the estimated average center of mass spatial position / optimized center of mass spatial position (preferably the optimized center of mass spatial position) of the calibration object and all spatially pointing straight lines / line segments as a measure of geometric error.

[0105] When the geometric calibration of the CBCT system is just completed, the radiation detector and the radiation source have not moved, and the average distance between the spatial position of the calibration object and the spatial pointing line / line segment should be very small. However, after the CBCT system has been running for a period of time, the radiation detector and the radiation source have moved slightly, and the average distance between the spatial position of the calibration object and the spatial pointing line / line segment will increase. Based on this, it is possible to determine whether the error of the geometric parameters of the CBCT system is normal (whether it exceeds the preset error range).

[0106] For the CBCT geometric error automatic acquisition method S100 of each of the above embodiments, preferably, in S108, obtaining the estimated average center-of-mass spatial position of the calibration object based on the acquired multiple estimated center-of-mass spatial positions of the calibration object includes:

[0107] The multiple estimated spatial positions of the centroid of the calibration object are averaged to obtain the estimated average spatial position of the centroid of the calibration object.

[0108] For the CBCT geometric error automatic acquisition method disclosed in the present invention, the shape of the calibration object described above is spherical.

[0109] According to another aspect of the present disclosure, a device for automatically acquiring geometric errors of a CBCT system is provided.

[0110] According to one embodiment of the present disclosure, a device for automatically acquiring geometric errors of a CBCT system includes:

[0111] A projection processing module, the projection processing module is based on capturing an imaging area including a calibration object disposed between the ray source and the detector to obtain projection images of multiple shooting angles;

[0112] A centroid spatial position acquisition module calculates the centroid spatial position of the calibration object based on projection images of multiple shooting angles of the calibration object and geometric parameters of the CBCT system;

[0113] The geometric error determination module obtains a geometric error characteristic value of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each projection image of multiple shooting angles to indicate the geometric error of the CBCT system.

[0114] According to another embodiment of the present disclosure, a device 1000 for automatically acquiring geometric errors of a CBCT system includes:

[0115] The centroid projection position acquisition module 1004 acquires the centroid projection position of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle;

[0116] The spatial pointing line / line segment acquisition module 1006 generates a spatial pointing line / line segment for each shooting angle based on the centroid projection position of the calibration object, the spatial position of the ray source, and the spatial position of the detector. The spatial pointing line / line segment passes through the centroid projection position and the spatial position of the ray source.

[0117] The estimated average center of mass spatial position acquisition module 1008 obtains a perpendicular line segment between any two spatially pointing straight lines / line segments, uses the midpoint of the perpendicular line segment as the estimated center of mass spatial position of the calibration object, and obtains the estimated average center of mass spatial position of the calibration object based on the obtained multiple estimated center of mass spatial positions of the calibration object;

[0118] The geometric error determination module 1010 obtains the distances between the estimated average center of mass spatial position of the calibration object and each spatial pointing straight line / line segment and generates an average distance of each distance to indicate the geometric error of the CBCT system.

[0119] In the present disclosure, the automatic geometric error acquisition device can be implemented in the form of a computer software architecture, and the automatic geometric error acquisition device can be set in the memory of a computer device.

[0120] According to a preferred embodiment of the present disclosure, the device 1000 for automatically acquiring geometric errors of a CBCT system further includes:

[0121] The projection image generation module 1002 can obtain projection images of three or more shooting angles based on projection data including a calibration object disposed between the ray source and the detector.

[0122] According to a preferred embodiment of the present disclosure, the geometric error automatic acquisition device 1000 of the CBCT system further includes:

[0123] The warning information generating module 1012 compares the average distance with a preset threshold distance, and generates geometric error warning information when the average distance is greater than or equal to the preset threshold distance.

[0124] The geometric error automatic acquisition device disclosed in the present invention may also be implemented through a hardware architecture including a processing system.

[0125] Figure 6 It is a schematic block diagram of the structure of a device for automatically acquiring geometric errors of a CBCT system using a hardware implementation of a processing system according to an embodiment of the present disclosure.

[0126] The CBCT system's geometric error automatic acquisition device 1000 may include corresponding modules for executing each or several steps in the above flowchart. Therefore, each or several steps in the above flowchart may be executed by a corresponding module, and the device may include one or more of these modules. The modules may be one or more hardware modules specifically configured to execute the corresponding steps, or implemented by a processor configured to execute the corresponding steps, or stored in a computer-readable medium for execution by the processor, or implemented by some combination thereof.

[0127] The hardware structure can be implemented using a bus architecture. The bus architecture can include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the hardware. Bus 1100 connects various circuits including one or more processors 1200, memory 1300, and / or hardware modules. Bus 1100 can also connect various other circuits 1400 such as peripherals, voltage regulators, power management circuits, external antennas, etc.

[0128] Bus 1100 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Component Architecture (EISA) bus. Buses can be classified as address buses, data buses, control buses, and the like. For ease of illustration, this figure shows only one connecting line, but this does not imply that there is only one bus or only one type of bus.

[0129] Any process or method description in the flowchart or otherwise described herein can be understood to represent a module, fragment or portion of code including one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present disclosure includes alternative implementations in which the functions may not be performed in the order shown or discussed, including performing the functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present disclosure belong. The processor performs the various methods and processes described above. For example, the method embodiments of the present disclosure can be implemented as a software program that is tangibly contained in a machine-readable medium, such as a memory. In some embodiments, part or all of the software program can be loaded and / or installed via a memory and / or a communication interface. When the software program is loaded into the memory and executed by the processor, one or more steps in the method described above can be performed. Alternatively, in other embodiments, the processor can be configured to perform one of the above methods in any other appropriate manner (e.g., by means of firmware).

[0130] The logic and / or steps represented in the flowchart or otherwise described herein may be embodied in any readable storage medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device).

[0131] For the purposes of this specification, a "readable storage medium" can be any device that can contain, store, communicate, propagate or transmit a program for use with or in conjunction with an instruction execution system, device or apparatus. More specific examples (a non-exhaustive list) of readable storage media include the following: an electrical connection having one or more wires (electronic device), a portable computer disk cartridge (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and editable read-only memory (EPROM or flash memory), a fiber optic device, and a portable read-only memory (CDROM). In addition, the readable storage medium can even be paper or other suitable medium on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in other suitable ways as necessary, and then storing it in a memory.

[0132] It should be understood that various parts of the present disclosure can be implemented using hardware, software, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement the hardware: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0133] Those skilled in the art will understand that all or part of the steps of the above-mentioned implementation method can be accomplished by instructing related hardware through a program, and the program can be stored in a readable storage medium. When the program is executed, it includes one or a combination of the steps of the method implementation method.

[0134] Furthermore, the functional units in the various embodiments of the present disclosure may be integrated into a single processing module, each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or software functional modules. If the integrated modules are implemented as software functional modules and sold or used as independent products, they may also be stored in a readable storage medium. The storage medium may be a read-only memory, a magnetic disk, or an optical disk, etc.

[0135] According to yet another aspect of the present disclosure, a CBCT system is provided.

[0136] A CBCT system according to one embodiment of the present disclosure includes:

[0137] Radiation source;

[0138] X-ray detectors;

[0139] a calibration object, the calibration object being arranged between the radiation source and the radiation detector;

[0140] The automatic geometric error acquisition device 1000 of any of the above embodiments acquires and / or outputs the geometric error of the CBCT system.

[0141] The basic architecture of the CBCT system may adopt the structure in the prior art, and the radiation source and radiation detector may also adopt the radiation source and radiation detector in the prior art, which are not particularly limited in the present disclosure.

[0142] According to a preferred embodiment of the present disclosure, the CBCT system further includes a holding device for stably maintaining the imaging part (head, jaw, etc.) of the imaging object (patient) within the imaging field of view of the CBCT system, and the calibration object is arranged on the holding device.

[0143] Figure 7 FIG1 is a schematic structural diagram (side view) of a CBCT system according to an embodiment of the present disclosure in which a calibration object is arranged on a holding device.

[0144] Since the calibration object ( Figure 7 The black sphere in the figure must be placed between the radiation source and the radiation detector and must not appear in the imaging field of view of the imaging part. In order to prevent motion artifacts caused by the patient's unconscious movement, a holding device is provided in dental CBCT systems. The holding device preferably includes a head clamp, a jaw support, and a support portion (such as a support rod). The head clamp and its fixed structure (support portion) generally do not appear in the imaging field of view of the imaging part. According to a preferred embodiment of the present disclosure, the calibration object is set on the support portion for supporting the head clamp and the jaw support.

[0145] Preferably, the calibration object is arranged in the holding device in an embedded manner.

[0146] The present disclosure also provides an electronic device, including: a memory, the memory storing execution instructions; and a processor or other hardware module, the processor or other hardware module executing the execution instructions stored in the memory, so that the processor or other hardware module performs the above method.

[0147] The present disclosure also provides a readable storage medium, in which execution instructions are stored. When the execution instructions are executed by a processor, they are used to implement the above method.

[0148] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms are not necessarily the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are mutually inconsistent.

[0149] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0150] Those skilled in the art will appreciate that the above embodiments are merely intended to clearly illustrate the present disclosure and are not intended to limit the scope of the present disclosure. Other changes or modifications may be made based on the above disclosure, and such changes or modifications are still within the scope of the present disclosure.

Claims

1. A method for automatically acquiring geometric errors of a CBCT system, characterized in that: include: A. photographing an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple viewing angles; B. Calculating the centroid spatial position of the calibration object based on the projection images of the multiple shooting angles of the calibration object and the geometric parameters of the CBCT system, including: S106, generating a spatial pointing straight line / line segment for each shooting angle based on the centroid projection position of the calibration object at each shooting angle, the spatial position of the ray source, and the spatial position of the detector, wherein the spatial pointing straight line / line segment passes through the centroid projection position and the spatial position of the ray source; and S108, obtaining a perpendicular line segment between any two of the spatial pointing straight lines / line segments, taking the midpoint of the perpendicular line segment as the estimated centroid spatial position of the calibration object, and obtaining an estimated average centroid spatial position of the calibration object based on the obtained multiple estimated centroid spatial positions of the calibration object; and C. Obtaining a geometric error characteristic value of the CBCT system based on the calculated spatial position of the center of mass of the calibration object and the projection position of the center of mass in each projection image of the multiple shooting angles to indicate the geometric error of the CBCT system, including: S110, obtaining the distance between the estimated average spatial position of the center of mass of the calibration object and each of the spatially pointing straight lines / line segments and generating an average distance of each of the distances to indicate the geometric error of the CBCT system; S112, comparing the average distance with a preset threshold distance, and generating a geometric error warning message when the average distance is greater than or equal to the preset threshold distance.

2. The method for automatically acquiring geometric errors of a CBCT system according to claim 1, characterized in that: The number of the calibration objects is one or more than two. When the number of the calibration objects is more than two, an average value of geometric error characteristic values ​​obtained based on the respective calibration objects is taken to indicate the geometric error of the CBCT system.

3. The method for automatically acquiring geometric errors of a CBCT system according to claim 1, characterized in that: A. Shooting an imaging area including a calibration object disposed between a radiation source and a detector to obtain projection images from multiple shooting angles, including: S102, photographing an imaging area including a calibration object disposed between a ray source and a detector to obtain projection images of three or more photographing viewing angles; and S104: Obtaining a projection position of the center of mass of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle.

4. The method for automatically acquiring geometric errors of a CBCT system according to claim 1, characterized in that: S110 is: obtaining the optimized spatial position of the center of mass of the calibration object based on the estimated average spatial position of the center of mass of the calibration object, obtaining the distance between the optimized spatial position of the center of mass of the calibration object and each of the spatial pointing straight lines / line segments, and generating an average distance of each of the distances to indicate the geometric error of the CBCT system.

5. The method for automatically acquiring geometric errors of a CBCT system according to claim 4, characterized in that: Obtaining an optimized center-of-mass spatial position of the calibration object based on the estimated average center-of-mass spatial position of the calibration object includes: The estimated average center of mass spatial position is optimized using an optimization algorithm / model to obtain the optimized center of mass spatial position of the calibration object.

6. The method for automatically acquiring geometric errors of a CBCT system according to claim 4, characterized in that: In S108, obtaining an estimated average spatial position of the center of mass of the calibration object based on the obtained multiple estimated spatial positions of the center of mass of the calibration object includes: An average of the multiple estimated center-of-mass spatial positions of the calibration object is taken to obtain the estimated average center-of-mass spatial position of the calibration object.

7. A device for automatically acquiring geometric errors of a CBCT system, characterized in that: include: A projection processing module, the projection processing module obtaining projection images of multiple shooting angles based on at least shooting an imaging area including a calibration object disposed between the ray source and the detector; a centroid spatial position acquisition module, which calculates the centroid spatial position of the calibration object based on the projection images of the multiple shooting angles of the calibration object and the geometric parameters of the CBCT system; as well as a geometric error determination module, configured to obtain a geometric error characteristic value of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each projection image of the multiple shooting angles to indicate a geometric error of the CBCT system; The projection processing module includes: a centroid projection position acquisition module, which acquires the centroid projection position of the calibration object in the projection image of each shooting angle based on the projection image of each shooting angle; and A spatial pointing line / line segment acquisition module, which generates a spatial pointing line / line segment for each shooting angle based on the centroid projection position of the calibration object at each shooting angle, the spatial position of the ray source, and the spatial position of the detector. The spatial pointing line / line segment passes through the centroid projection position and the spatial position of the ray source. The centroid spatial position acquisition module includes: an estimated average center of mass spatial position acquisition module, the estimated average center of mass spatial position acquisition module acquiring a perpendicular line segment between any two of the spatially pointing straight lines / line segments, taking the midpoint of the perpendicular line segment as the estimated center of mass spatial position of the calibration object, and obtaining the estimated average center of mass spatial position of the calibration object based on the acquired multiple estimated center of mass spatial positions of the calibration object; The geometric error determination module obtains the distances between the estimated average center of mass spatial position of the calibration object and each of the spatial pointing straight lines / line segments and generates an average distance of each of the distances to indicate the geometric error of the CBCT system; The geometric error determination module further includes: A warning information generation module is configured to compare the average distance with a preset threshold distance, and to generate geometric error warning information when the average distance is greater than or equal to the preset threshold distance.

8. The device for automatically acquiring geometric errors of a CBCT system according to claim 7, characterized in that: The projection processing module also includes: A projection image generation module is provided, wherein the projection image generation module obtains projection images of three or more shooting angles based on projection data of a calibration object disposed between a ray source and a detector.

9. A CBCT system, characterized in that: include: Radiation source; X-ray detectors; a calibration object, the calibration object being disposed between the radiation source and the radiation detector; and The automatic geometric error acquisition device according to claim 7 or 8, wherein the automatic geometric error acquisition device acquires and / or outputs the geometric error of the CBCT system.

10. The CBCT system according to claim 9, wherein: It also includes a holding device, which is used to stably hold the imaging part of the imaging object within the imaging field of view of the CBCT system, and the calibration object is set on the holding device.

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