CN114041816A - Method and device for automatically acquiring geometric errors of CBCT (cone beam computed tomography) system - Google Patents
Method and device for automatically acquiring geometric errors of CBCT (cone beam computed tomography) system Download PDFInfo
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Abstract
The present disclosure provides a method for automatically acquiring a geometric error of a CBCT system, including: shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of a plurality of shooting visual angles; calculating the mass center space position of the calibration object based on the projection images of the plurality of shooting visual angles of the calibration object and the geometric parameters of the CBCT system; and acquiring a geometric error characteristic value of the CBCT system based on the calculated mass center space position of the calibration object and the mass center projection position in each projection image of the plurality of shooting visual angles to indicate the geometric error of the CBCT system. The disclosure also provides a device for automatically acquiring the geometric error of the CBCT system and the CBCT system.
Description
Technical Field
The present disclosure relates to the field of CT technologies, and in particular, to a method and an apparatus for automatically acquiring a geometric error of a CBCT system.
Background
Based on various reconstruction algorithms, the CBCT equipment can generate three-dimensional images, and great help is provided for diagnosis of various diseases. And one basis for the reconstruction algorithm is the correct geometric relationship. The geometric relationship refers to the relative relationship among the radiation source, the rotating shaft and the detector.
Only based on the correct geometric relationship, the correct three-dimensional image can be reconstructed. Therefore, all CBCT devices need to acquire the correct geometric relationship by a certain means during the installation process and store the same in the CBCT devices, and then the pre-stored geometric relationship is automatically called during the shooting process to reconstruct the image.
However, since CBCT is a moving system, the detector and the source both rotate around the rotation axis, and the detector and the source are easily moved slightly after being used for too long or too many times, which causes the geometric relationship to be inaccurate, and thus, geometric artifacts are often visible in the reconstructed image.
The geometric artifacts can affect the imaging quality and distort the imaging results. For example, geometric artifacts may cause an originally clear root canal to become unclear or deform, artifacts may even cause a doctor to misjudge that a tooth has a crack, and the like, and a doctor generally does not know professional CT knowledge, but takes a patient to have a severe geometric deformation for many times to realize that a problem is generated in CT imaging, and makes it more difficult for the doctor to find the geometric problem in time, and does not contact a CT equipment manufacturer in time, so that the image of the patient is a problematic image after the geometric problem occurs.
Disclosure of Invention
In order to solve at least one of the above technical problems, the present disclosure provides a method for automatically acquiring a geometric error of a CBCT system, an apparatus for automatically acquiring a geometric error of a CBCT system, and a CBCT system.
According to an aspect of the present disclosure, there is provided a method for automatically acquiring a geometric error of a CBCT system, including:
A. shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of a plurality of shooting visual angles;
B. calculating the mass center space position of the calibration object based on the projection images of the plurality of shooting visual angles of the calibration object and the geometric parameters of the CBCT system;
C. acquiring a geometric error characteristic value of the CBCT system based on the calculated mass center spatial position of the calibration object and the mass center projection position in each projection image of the plurality of shooting visual angles to indicate the geometric error of the CBCT system.
According to the method for automatically acquiring the geometric error of the CBCT system in at least one embodiment of the present disclosure, the number of the calibration objects is one or more than two, and when the number of the calibration objects is more than two, an average value of the geometric error characteristic values obtained based on the respective calibration objects is taken to indicate the geometric error of the CBCT system.
According to at least one embodiment of the present disclosure, an automatic geometric error acquiring method for a CBCT system includes a step of capturing an imaging region including a calibration object disposed between a radiation source and a detector to obtain projection images of a plurality of capturing views, including:
s102, shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of more than three shooting visual angles;
and S104, acquiring the centroid projection position of the calibration object in the projection image of each shooting visual angle based on the projection image of each shooting visual angle.
According to at least one embodiment of the present disclosure, the method for automatically acquiring geometric errors of a CBCT system, B, calculating a centroid space position of a calibration object based on projection images of the plurality of shooting view angles of the calibration object and geometric parameters of the CBCT system, includes:
s106, generating a space pointing straight line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, wherein the space pointing straight line/line segment passes through the centroid projection position and the space position of the ray source;
S108, obtaining a vertical line segment between any two spatial directional straight lines/line segments, taking the midpoint of the vertical line segment as the estimated mass center spatial position of the calibration object, and obtaining the estimated average mass center spatial position of the calibration object based on the plurality of acquired estimated mass center spatial positions of the calibration object.
According to at least one embodiment of the present disclosure, a method for automatically acquiring a geometric error of a CBCT system, C, acquiring a geometric error characteristic value of the CBCT system based on a calculated centroid space position of the calibration object and a centroid projection position in each projection image of the plurality of photographing view angles to indicate a geometric error of the CBCT system, includes:
s110, obtaining the distance between the estimated average mass center space position of the calibration object and each space pointing straight line/line segment, and generating the average distance of each distance to indicate the geometric error of the CBCT system.
According to at least one embodiment of the present disclosure, in the method for automatically acquiring geometric errors of a CBCT system, S110 is: and obtaining an optimized mass center spatial position of the calibration object based on the estimated average mass center spatial position of the calibration object, obtaining distances between the optimized mass center spatial position of the calibration object and each spatial directional straight line/line segment, and generating an average distance of each distance to indicate the geometric error of the CBCT system.
According to at least one embodiment of the present disclosure, a method for automatically acquiring geometric errors of a CBCT system, which obtains an optimized centroid space position of a calibration object based on a pre-estimated average centroid space position of the calibration object, includes:
and optimizing the estimated average mass center spatial position by using an optimization algorithm/model to obtain an optimized mass center spatial position of the calibration object.
According to at least one embodiment of the present disclosure, a method for automatically acquiring a geometric error of a CBCT system, C, acquiring a geometric error feature value of the CBCT system based on the calculated centroid space position of the calibration object and the centroid projection position in each projection image of the plurality of photographing view angles to indicate the geometric error of the CBCT system, further includes:
and S112, comparing the average distance with a preset threshold distance, and generating geometric error warning information when the average distance is greater than or equal to the preset threshold distance.
In the method for automatically acquiring geometric errors of a CBCT system according to at least one embodiment of the present disclosure, in S108, obtaining an estimated average spatial position of the centroid of the calibration object based on the acquired plurality of estimated spatial positions of the centroid of the calibration object includes:
And averaging the plurality of estimated mass center spatial positions of the calibration object to obtain an estimated average mass center spatial position of the calibration object.
According to another aspect of the present disclosure, there is provided an automatic geometric error acquisition apparatus for a CBCT system, including:
the projection processing module is used for shooting an imaging area comprising a calibration object arranged between the ray source and the detector at least to obtain projection images of a plurality of shooting visual angles;
a centroid spatial position acquisition module which calculates a centroid spatial position of the calibration object based on the projection images of the plurality of photographing view angles of the calibration object and a geometric parameter of the CBCT system;
a geometric error determination module that acquires a geometric error feature value of the CBCT system to indicate a geometric error of the CBCT system based on the calculated centroid spatial position of the calibration object and the centroid projection position in each of the projection images of the plurality of photographing view angles.
According to the automatic geometric error acquisition device of the CBCT system of at least one embodiment of the present disclosure, the projection processing module comprises:
The centroid projection position acquisition module acquires the centroid projection position of a calibration object in the projection images of all the shooting visual angles based on the projection images of all the shooting visual angles;
the space direction line/line segment acquisition module generates a space direction line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, and the space direction line/line segment passes through the centroid projection position and the space position of the ray source.
According to the automatic geometric error acquisition device of the CBCT system of at least one embodiment of the present disclosure, the centroid space position acquisition module includes:
the device comprises a pre-estimated average mass center space position obtaining module, wherein the pre-estimated average mass center space position obtaining module obtains a perpendicular line section between any two spatial directional straight lines/line sections, takes the midpoint of the perpendicular line section as the pre-estimated mass center space position of the calibration object, and obtains the pre-estimated average mass center space position of the calibration object based on a plurality of pre-estimated mass center space positions of the calibration object.
According to the automatic geometric error acquisition device of the CBCT system in at least one embodiment of the present disclosure, the geometric error determination module acquires distances between the estimated average centroid spatial position of the calibration object and each of the spatial directional lines/line segments and generates an average distance of each of the distances to indicate the geometric error of the CBCT system.
According to at least one embodiment of the present disclosure, the automatic geometric error acquisition apparatus for a CBCT system, the projection processing module further includes:
and the projection image generation module is used for obtaining projection images of more than three shooting visual angles based on projection data of a calibration object arranged between the ray source and the detector.
According to the automatic geometric error acquisition device of the CBCT system of at least one embodiment of the present disclosure, the geometric error determination module further includes:
and the warning information generation module 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.
According to yet another aspect of the present disclosure, there is provided a CBCT system, including: a radiation source; a radiation detector; the calibration object is arranged between the ray source and the ray detector; the automatic geometric error acquisition device according to any one of the above embodiments, wherein the automatic geometric error acquisition device acquires and/or outputs the geometric error of the CBCT system.
A CBCT system in accordance with at least one embodiment of the present disclosure further includes a holding device for stably holding an imaging site of an imaging subject within an imaging field of view of the CBCT system, the calibration object being disposed on the holding device.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.
Fig. 1 is a schematic flow chart diagram illustrating a method for automatically acquiring geometric errors of a CBCT system according to an embodiment of the present disclosure.
Fig. 2 is a schematic flow chart diagram illustrating a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.
Fig. 3 is a flowchart illustrating a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.
Fig. 4 is a flowchart illustrating a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.
Fig. 5 is a flowchart illustrating an automatic geometric error acquisition method S100 of a CBCT system according to still another embodiment of the disclosure.
Fig. 6 is a block diagram illustrating a structure of an automatic geometric error acquiring apparatus of a CBCT system implemented in hardware using a processing system according to an embodiment of the present disclosure.
FIG. 7 is a schematic structural view (side view) of a CBCT system with calibration objects disposed on a holder according to one embodiment of the present disclosure.
Description of the reference numerals
1000 geometric error automatic acquisition device
1002 projection image generation module
1004 centroid projection position acquisition module
1006 space direction straight line/line segment acquisition module
1008 pre-estimating the average centroid space position
1010 geometric error determination module
1012 warning information generating module
1100 bus
1200 processor
1300 memory
1400 and other circuits.
Detailed Description
The present disclosure will be described in further detail with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present disclosure. It should be further noted that, for the convenience of description, only the portions relevant to the present disclosure are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. Technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Unless otherwise indicated, the illustrated exemplary embodiments/examples are to be understood as providing exemplary features of various details of some ways in which the technical concepts of the present disclosure may be practiced. Accordingly, unless otherwise indicated, features of the various embodiments may be additionally combined, separated, interchanged, and/or rearranged without departing from the technical concept of the present disclosure.
The use of cross-hatching and/or shading in the drawings is generally used to clarify the boundaries between adjacent components. As such, unless otherwise noted, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for a particular material, material property, size, proportion, commonality between the illustrated components and/or any other characteristic, attribute, property, etc., of a component. Further, in the drawings, the size and relative sizes of components may be exaggerated for clarity and/or descriptive purposes. While example embodiments may be practiced differently, the specific process sequence may be performed in a different order than that described. For example, two processes described consecutively may be performed substantially simultaneously or in reverse order to that described. In addition, like reference numerals denote like parts.
When an element is referred to as being "on" or "on," "connected to" or "coupled to" another element, it can be directly on, connected or coupled to the other element or intervening elements may be present. However, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element, there are no intervening elements present. For purposes of this disclosure, the term "connected" may refer to physically, electrically, etc., and may or may not have intermediate components.
The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, when the terms "comprises" and/or "comprising" and variations thereof are used in this specification, the presence of stated features, integers, steps, operations, elements, components and/or groups thereof are stated but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. It is also noted that, as used herein, the terms "substantially," "about," and other similar terms are used as approximate terms and not as degree terms, and as such, are used to interpret inherent deviations in measured values, calculated values, and/or provided values that would be recognized by one of ordinary skill in the art.
The following describes the automatic geometric error acquisition method of the CBCT system, the automatic geometric error acquisition device of the CBCT system, and the CBCT system in detail with reference to fig. 1 to 7.
Fig. 1 is a schematic flow chart diagram illustrating a method for automatically acquiring geometric errors of a CBCT system according to an embodiment of the present disclosure.
As shown in fig. 1, the method for automatically acquiring geometric errors of a CBCT system of the present disclosure includes:
A. shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of a plurality of shooting visual angles;
B. calculating the mass center space position of the calibration object based on the projection images of the plurality of shooting visual angles of the calibration object and the geometric parameters of the CBCT system;
C. and acquiring a geometric error characteristic value of the CBCT system based on the calculated mass center space position of the calibration object and the mass center projection position in each projection image of the plurality of shooting visual angles to indicate the geometric error of the CBCT system.
When the number of the calibration objects is more than two, the geometric error characteristic value obtained based on each calibration object is averaged to indicate the geometric error of the CBCT system.
Fig. 2 is a schematic flow chart diagram illustrating a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.
Referring to fig. 2, the method S100 for automatically acquiring geometric errors of a CBCT system according to this embodiment includes:
s102, shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of more than three shooting visual angles;
s104, acquiring the centroid projection position of the calibration object in the projection image of each shooting visual angle based on the projection image of each shooting visual angle;
s106, generating a space pointing straight line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, wherein the space pointing straight line/line segment passes through the centroid projection position and the space position of the ray source;
s108, acquiring a vertical line segment between any two spatial directional straight lines/line segments, taking the midpoint of the vertical line segment as an estimated mass center spatial position of the calibration object, and acquiring an estimated average mass center spatial position of the calibration object based on a plurality of acquired estimated mass center spatial positions of the calibration object;
s110, obtaining the distances between the estimated average mass center space position of the calibration object and each space pointing straight line/line segment and generating the average distance of each distance to indicate the geometric error of the CBCT system.
The CBCT system (i.e., cone-beam CT system) includes a radiation source and a radiation detector, generally an X-ray source and an X-ray detector, and can photograph a positive slice and a lateral slice of an imaging portion of an imaging object through the CBCT system, and also can synchronously drive the radiation source and the radiation detector to rotate, so as to obtain a CT image (three-dimensional image) of the imaging portion.
The method comprises the steps of utilizing the geometrical parameters of the existing CBCT system to obtain the space position of a ray source and the space position of a detector under certain shooting visual angles, and meanwhile, directly calculating the actual coordinate (namely the space coordinate) of a projection position based on the image position (pixel coordinate) of a calibration object (such as a steel ball) projected on a projection image, so that a line/line segment of the image position of the projection image, which points to the calibration object from the ray source, in a space can be obtained under any shooting visual angle of the steel ball. This operation is performed for each shooting angle of view at which the steel ball is shot, and a series of lines/line segments in space can be obtained.
Ideally, these lines/line segments must meet at a point, which is the actual spatial coordinates of the calibration object, but due to the error, even if the geometric parameters have just been calibrated, these lines cannot meet at a point.
The acquisition of the geometric parameters may be performed by a method disclosed in chinese patent application 2021105915312 (geometric parameter acquisition method and acquisition system of cone beam CT system), and is not described in detail.
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, and the size of the calibration object can be adjusted by those skilled in the art based on the indication precision of the geometric error.
In step S110 in this embodiment, the geometric error of the CBCT system is indicated by the average distance between the estimated average centroid spatial position of the calibration object and the distance between each spatial directional line/line segment.
Fig. 3 is a flowchart illustrating a method for automatically acquiring geometric errors of a CBCT system according to another embodiment of the present disclosure.
As shown in fig. 3, the method S100 for automatically acquiring a geometric error of a CBCT system according to the present embodiment includes:
s102, shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of more than three shooting visual angles;
s104, acquiring the centroid projection position of the calibration object in the projection image of each shooting visual angle based on the projection image of each shooting visual angle;
S106, generating a space pointing straight line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, wherein the space pointing straight line/line segment passes through the centroid projection position and the space position of the ray source;
s108, acquiring a vertical line segment between any two spatial directional straight lines/line segments, taking the midpoint of the vertical line segment as an estimated mass center spatial position of the calibration object, and acquiring an estimated average mass center spatial position of the calibration object based on a plurality of acquired estimated mass center spatial positions of the calibration object;
s110, obtaining an optimized centroid space position of the calibration object based on the estimated average centroid space position of the calibration object, obtaining distances between the optimized centroid space position of the calibration object and each space pointing straight line/line segment, and generating an average distance of each distance to indicate a geometric error of the CBCT system.
In step S110 of the present embodiment, the geometric error of the CBCT system is indicated by an average distance of the distances between the optimized centroid spatial position of the calibration object and each spatial directional line/line segment.
For the above embodiments of the method S100 for automatically acquiring geometric errors of a CBCT system, preferably, obtaining an optimized centroid space position of the calibration object based on the estimated average centroid space position of the calibration object includes:
And optimizing the estimated average mass center spatial position by using an optimization algorithm/model to obtain the optimized mass center spatial position of the calibration object.
According to the preferred embodiment of the present disclosure, the centroid space position of the calibration object is used as a parameter to be optimized of the optimization algorithm/model, the sum of the distances between the estimated average centroid space position of the calibration object and each spatial directional straight line/line segment is used as a target function of the optimization algorithm/model, and the estimated average centroid space position of the calibration object is used as an initial parameter of the optimization algorithm/model, so that the local minimum of the target function can be obtained, thereby obtaining the optimized centroid space position of the calibration object (obtaining the parameter to be optimized).
Wherein the optimization algorithm/model may use the Nelder-Mead algorithm.
For the above-mentioned automatic geometric error acquisition method S100 of the CBCT system of each embodiment, it is preferable that the method further includes:
and S112, comparing the average distance with a preset threshold distance, and generating geometric error warning information when the average distance is greater than or equal to the preset threshold distance.
Fig. 4 is a schematic flowchart of a method S100 for automatically acquiring geometric errors of a CBCT system according to still another embodiment of the present disclosure, and fig. 5 is a schematic flowchart of the method S100 for automatically acquiring geometric errors of a CBCT system according to still another embodiment of the present disclosure.
The method for automatically acquiring the geometric error uses the obtained average estimated centroid space position/optimized centroid space position (preferably optimized centroid space position) of the calibration object and the mean value of the distances between all spatial directional lines/line segments as the measurement standard of the geometric error.
When the geometric calibration of the CBCT system is just completed, the ray detector and the ray source do not move, and the average value of the distance between the space position of the calibration object and the space pointing straight line/line segment is small; and when the CBCT system operates for a period of time, the ray detector and the ray source slightly move, the average value of the distance between the space position of the calibration object and the space pointing straight line/line segment will be enlarged, and based on the average value, whether the error of the geometric parameters of the CBCT system is normal (whether the error exceeds the preset error range) can be judged.
For the above CBCT geometric error automatic acquisition method S100 of each embodiment, preferably, in S108, obtaining an estimated average centroid space position of the calibration object based on the acquired plurality of estimated centroid space positions of the calibration object includes:
and averaging the plurality of estimated mass center spatial positions of the calibration object to obtain an estimated average mass center spatial position of the calibration object.
For the CBCT geometric error automatic acquisition method of the present disclosure, the shape of the calibration object described above is a spherical shape.
According to another aspect of the present disclosure, an automatic geometric error acquisition apparatus for a CBCT system is provided.
According to an embodiment of this disclosure, the geometrical error automatic acquisition device of CBCT system includes:
the projection processing module is used for shooting an imaging area comprising a calibration object arranged between the ray source and the detector at least to obtain projection images of a plurality of shooting visual angles;
the mass center spatial position acquisition module calculates the mass center spatial position of the calibration object based on the projection images of the plurality of shooting visual angles of the calibration object and the geometric parameters of the CBCT system;
and the geometric error determination module acquires a geometric error characteristic value of the CBCT system based on the calculated mass center spatial position of the calibration object and the mass center projection position in each projection image of the plurality of shooting visual angles so as to indicate the geometric error of the CBCT system.
An automatic geometric error acquisition apparatus 1000 for a CBCT system according to another embodiment of the present disclosure includes:
the centroid projection position acquisition module 1004 acquires the centroid projection position of the calibration object in the projection image of each shooting visual angle based on the projection image of each shooting visual angle;
A spatial direction line/segment acquisition module 1006, wherein the spatial direction line/segment acquisition module 1006 generates a spatial direction line/segment of each shooting view angle based on the centroid projection position of the calibration object of each shooting view angle, the spatial position of the ray source and the spatial position of the detector, and the spatial direction line/segment passes through the centroid projection position and the spatial position of the ray source;
the estimated average mass center spatial position obtaining module 1008 obtains a perpendicular line segment between any two spatial directional straight lines/line segments, uses the midpoint of the perpendicular line segment as the estimated mass center spatial position of the calibration object, and obtains the estimated average mass center spatial position of the calibration object based on the obtained estimated mass center spatial positions of the calibration object;
the geometric error determination module 1010, the geometric error determination module 1010 obtains distances between the estimated average centroid spatial position of the calibration object and each spatial directional line/segment and generates an average distance of each distance to indicate the geometric error of the CBCT system.
In the present disclosure, the automatic geometric error acquiring device may be implemented in the form of a computer software architecture, and the automatic geometric error acquiring device may be disposed in a memory of a computer device.
According to the preferred embodiment of the present disclosure, the automatic geometric error acquiring apparatus 1000 of the CBCT system further includes:
the projection image generation module 1002, the projection image generation module 1002 can obtain projection images of three or more shooting viewing angles based on projection data including a calibration object disposed between the ray source and the detector.
According to a preferred embodiment of the present disclosure, the automatic geometric error acquiring apparatus 1000 of the CBCT system further includes:
the warning information generating module 1012, 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.
The automatic geometric error acquisition apparatus of the present disclosure may also be implemented by a hardware architecture including a processing system.
Fig. 6 is a block diagram illustrating a structure of an automatic geometric error acquiring apparatus of a CBCT system implemented in hardware using a processing system according to an embodiment of the present disclosure.
The automatic geometric error acquisition device 1000 of the CBCT system may include corresponding modules for performing each or several steps of the above-described flowcharts. Thus, each step or several steps in the above-described flow charts may be performed by a respective module, and the apparatus may comprise one or more of these modules. The modules may be one or more hardware modules specifically configured to perform the respective steps, or implemented by a processor configured to perform the respective steps, or stored within a computer-readable medium for implementation by a processor, or by some combination.
The hardware architecture may be implemented using a bus architecture. The bus architecture may include any number of interconnecting buses and bridges depending on the specific application of the hardware and the overall design constraints. The bus 1100 couples various circuits including the one or more processors 1200, the memory 1300, and/or the hardware modules together. The bus 1100 may also connect various other circuits 1400, such as peripherals, voltage regulators, power management circuits, external antennas, and the like.
The bus 1100 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one connection line is shown, but no single bus or type of bus is shown.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and the scope of the preferred embodiments of the present disclosure includes other implementations in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the implementations of the present disclosure. The processor performs the various methods and processes described above. For example, method embodiments in the present disclosure may be implemented as a software program tangibly embodied in a machine-readable medium, such as a memory. In some embodiments, some or all of the software program may be loaded and/or installed via memory and/or a communication interface. When the software program is loaded into memory and executed by a processor, one or more steps of the method described above may be performed. Alternatively, in other embodiments, the processor may be configured to perform one of the methods described above by any other suitable means (e.g., by means of firmware).
The logic and/or steps represented in the flowcharts or otherwise described herein may be embodied in any readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions.
For the purposes of this description, a "readable storage medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the readable storage medium include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable read-only memory (CDROM). In addition, the readable storage medium may even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in the memory.
It should be understood that portions of the present disclosure may be implemented in hardware, software, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps of the method implementing the above embodiments may be implemented by hardware that is instructed to be associated with a program, which may be stored in a readable storage medium, and which, when executed, includes one or a combination of the steps of the method embodiments.
In addition, each functional unit in the embodiments of the present disclosure may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a separate product, may also be stored in a readable storage medium. The storage medium may be a read-only memory, a magnetic or optical disk, or the like.
In accordance with yet another aspect of the present disclosure, a CBCT system is provided.
A CBCT system according to an embodiment of the present disclosure includes:
a radiation source;
a radiation detector;
the calibration object is arranged between the ray source and the ray detector;
in the automatic geometric error acquisition apparatus 1000 according to any of the above embodiments, the automatic geometric error acquisition apparatus 1000 acquires and/or outputs the geometric error of the CBCT system.
The basic architecture of the CBCT system may adopt a structure in the prior art, and the radiation source and the radiation detector may also adopt a structure in the prior art, which is not particularly limited in this disclosure.
The CBCT system according to the preferred embodiment of the present disclosure further includes a holding device for stably holding an imaging site (head, jaw, etc.) of an imaging object (patient) within an imaging field of view of the CBCT system, the calibration object being disposed on the holding device.
FIG. 7 is a schematic structural view (side view) of a CBCT system with calibration objects disposed on a holder according to one embodiment of the present disclosure.
Since the calibration object (black sphere in fig. 7) must be placed in the middle between the radiation source and the radiation detector and cannot appear in the imaging field of view in which the imaging region is imaged. In order to prevent motion artifacts caused by involuntary movements of the patient, such as in a dental CBCT system, a holding device is provided, which preferably comprises a head clamp, a jaw rest, a support (e.g. a support bar), and generally neither the head clamp nor its fixation structure (support) is present in the imaging field of view of the imaging site. According to a preferred embodiment of the present disclosure, the calibration objects are disposed on a support portion for supporting the head clip and jaw rest.
Preferably, the calibration object is arranged in an embedded manner on the holding device.
The present disclosure also provides an electronic device, including: a memory storing execution instructions; and a processor or other hardware module that executes the execution instructions stored by the memory, causing the processor or other hardware module to perform the above-described methods.
The present disclosure also provides a readable storage medium having stored therein execution instructions, which when executed by a processor, are used to implement the above-mentioned method.
In the description herein, reference to the description of the terms "one embodiment/implementation," "some embodiments/implementations," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment/implementation or example is included in at least one embodiment/implementation or example of the present application. In this specification, the schematic representations of the terms described above are not necessarily the same embodiment/mode or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments/modes or examples. Furthermore, the various embodiments/aspects or examples and features of the various embodiments/aspects or examples described in this specification can be combined and combined by one skilled in the art without conflicting therewith.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
It will be understood by those skilled in the art that the foregoing embodiments are merely for clarity of illustration of the disclosure and are not intended to limit the scope of the disclosure. Other variations or modifications may occur to those skilled in the art, based on the foregoing disclosure, and are still within the scope of the present disclosure.
Claims (10)
1. A method for automatically acquiring geometric errors of a CBCT system is characterized by comprising the following steps:
A. shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of a plurality of shooting visual angles;
B. calculating the mass center space position of the calibration object based on the projection images of the plurality of shooting visual angles of the calibration object and the geometric parameters of the CBCT system; and
C. Acquiring a geometric error characteristic value of the CBCT system based on the calculated mass center spatial position of the calibration object and the mass center projection position in each projection image of the plurality of shooting visual angles to indicate the geometric error of the CBCT system.
2. The method for automatically acquiring geometric errors of a CBCT system according to claim 1, wherein the number of the calibration objects is one or more than two, and when the number of the calibration objects is more than two, the geometric errors of the CBCT system are indicated by averaging the geometric error characteristic values obtained based on each of the calibration objects.
3. The method for automatically acquiring geometric errors of a CBCT system according to claim 1, wherein a, capturing an imaging region including a calibration object disposed between the radiation source and the detector, and obtaining projection images of a plurality of capturing views comprises:
s102, shooting an imaging area comprising a calibration object arranged between a ray source and a detector to obtain projection images of more than three shooting visual angles; and
and S104, acquiring the centroid projection position of the calibration object in the projection image of each shooting visual angle based on the projection image of each shooting visual angle.
4. The automatic geometric error acquisition method for a CBCT system according to claim 3, wherein the step of calculating the spatial position of the centroid of the calibration object based on the projection images of the plurality of shooting views of the calibration object and the geometric parameters of the CBCT system comprises:
s106, generating a space pointing straight line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, wherein the space pointing straight line/line segment passes through the centroid projection position and the space position of the ray source; and
s108, obtaining a vertical line segment between any two spatial directional straight lines/line segments, taking the midpoint of the vertical line segment as the estimated mass center spatial position of the calibration object, and obtaining the estimated average mass center spatial position of the calibration object based on the plurality of acquired estimated mass center spatial positions of the calibration object.
5. The automatic geometric error acquisition method for a CBCT system according to claim 4, wherein C, acquiring a geometric error characteristic value of the CBCT system based on the calculated spatial position of the centroid of the calibration object and the projected position of the centroid in each of the plurality of projection images of the capturing views to indicate the geometric error of the CBCT system, comprises:
S110, obtaining the distance between the estimated average mass center space position of the calibration object and each space pointing straight line/line segment, and generating the average distance of each distance to indicate the geometric error of the CBCT system.
6. The method for automatically acquiring geometric errors of a CBCT system according to claim 5, wherein S110 is: and obtaining an optimized mass center spatial position of the calibration object based on the estimated average mass center spatial position of the calibration object, obtaining distances between the optimized mass center spatial position of the calibration object and each spatial directional straight line/line segment, and generating an average distance of each distance to indicate the geometric error of the CBCT system.
7. The method of claim 6, wherein obtaining the optimized centroid space position of the calibration object based on the estimated average centroid space position of the calibration object comprises:
and optimizing the estimated average mass center spatial position by using an optimization algorithm/model to obtain an optimized mass center spatial position of the calibration object.
8. The automatic geometric error acquisition method for a CBCT system according to claim 5 or 6, wherein C, acquiring a geometric error characteristic value of the CBCT system based on the calculated spatial position of the centroid of the calibration object and the centroid projection position in each projection image of the plurality of photographing view angles to indicate the geometric error of the CBCT system, further comprises:
S112, comparing the average distance with a preset threshold distance, and generating geometric error warning information when the average distance is greater than or equal to the preset threshold distance;
preferably, in S108, obtaining an estimated average centroid space position of the calibration object based on the obtained plurality of estimated centroid space positions of the calibration object includes:
and averaging the plurality of estimated mass center spatial positions of the calibration object to obtain an estimated average mass center spatial position of the calibration object.
9. An automatic geometric error acquisition device of a CBCT system is characterized by comprising:
the projection processing module is used for shooting an imaging area comprising a calibration object arranged between the ray source and the detector at least to obtain projection images of a plurality of shooting visual angles;
a centroid spatial position acquisition module which calculates a centroid spatial position of the calibration object based on the projection images of the plurality of photographing view angles of the calibration object and a geometric parameter of the CBCT system; and
a geometric error determination module that acquires a geometric error feature value of the CBCT system to indicate a geometric error of the CBCT system based on the calculated centroid space position of the calibration object and the centroid projection position in each of the projection images of the plurality of photographing view angles;
Preferably, the projection processing module includes:
the centroid projection position acquisition module acquires the centroid projection position of a calibration object in the projection images of all the shooting visual angles based on the projection images of all the shooting visual angles; and
the space pointing straight line/line segment acquisition module generates a space pointing straight line/line segment of each shooting visual angle based on the centroid projection position of the calibration object of each shooting visual angle, the space position of the ray source and the space position of the detector, and the space pointing straight line/line segment passes through the centroid projection position and the space position of the ray source;
preferably, the centroid space position acquisition module includes:
a pre-estimated average centroid spatial position acquisition module, wherein the pre-estimated average centroid spatial position acquisition module acquires a perpendicular line segment between any two spatial directional straight lines/line segments, takes a midpoint of the perpendicular line segment as a pre-estimated centroid spatial position of the calibration object, and acquires the pre-estimated average centroid spatial position of the calibration object based on a plurality of pre-estimated centroid spatial positions of the calibration object;
Preferably, the geometric error determination module obtains distances between the estimated average centroid spatial position of the calibration object and each of the spatial directional lines/line segments and generates an average distance of each of the distances to indicate a geometric error of the CBCT system;
preferably, the projection processing module further comprises:
the projection image generation module is used for obtaining projection images of more than three shooting visual angles based on projection data of a calibration object arranged between the ray source and the detector;
preferably, the geometric error determination module further comprises:
and the warning information generation module 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.
10. A CBCT system, comprising:
a radiation source;
a radiation detector;
the calibration object is arranged between the ray source and the ray detector; the automatic geometric error acquisition device of claim 9, which acquires and/or outputs the geometric error of the CBCT system;
Preferably, the system further comprises a holding device, wherein the holding device is used for stably holding the imaging position of the imaging object in the imaging visual field of the CBCT system, and the calibration object is arranged on the holding device.
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