CT equipment calibration methods, apparatus, equipment, media, and procedures based on energy spectrum shape.

Abstract

This invention provides a CT equipment calibration method, apparatus, device, medium, and program product based on energy spectrum shape, relating to the fields of physics and computer science, and particularly to the application of physics and computer technology in the field of radiomedicine. The method includes: constructing an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters describing the characteristics of the energy spectrum distribution; obtaining measured CT values ​​for various materials based on CT equipment scanning of reference materials, wherein the reference materials include various materials with known densities and elemental mass percentages; determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of the various materials, thereby obtaining the energy spectrum shape information of the CT equipment.

Description

Technical Field

[0001] This invention relates to the fields of physics and computer science, specifically to the application of physics and computer technology in the field of radiomedicine, and more specifically to a CT equipment calibration method, apparatus, device, medium, and program product based on energy spectrum shape. Background Technology

[0002] In the field of radiomedical surgery, CT scanners play an irreplaceable role. The energy spectrum information of a CT scanner describes the distribution characteristics of photon energy and has a profound impact on CT imaging quality, diagnostic accuracy, and radiation dose control. However, due to the characteristics of the X-ray tube, target materials, and filters, as well as manufacturers' confidentiality policies, the energy spectrum information of a CT scanner is usually not directly obtainable. Therefore, it is necessary to calibrate the CT scanner using certain methods to obtain its energy spectrum information, thereby establishing a correspondence between CT values ​​and the actual composition of materials.

[0003] If the energy spectrum information of CT equipment is inaccurate, it may lead to problems such as decreased quality of CT image post-processing, reduced diagnostic accuracy, and failure of radiation dose control. Improving the accuracy of the energy spectrum information obtained from CT equipment is an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a CT equipment calibration method, apparatus, device, medium, and program product based on energy spectrum shape, which at least partially solves one of the above-mentioned technical problems.

[0005] According to a first aspect of the present invention, a CT device calibration method based on energy spectrum shape is provided, comprising: constructing an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters for describing the energy spectrum distribution characteristics; obtaining measured CT values ​​of various materials based on CT device scanning of reference materials, wherein the reference materials include various materials with known densities and elemental mass percentages; determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials, thereby obtaining energy spectrum shape information of the CT device.

[0006] According to an embodiment of the present invention, the method further includes: discretizing the energy spectrum shape function based on the energy range to obtain a discretized probability distribution vector, wherein the probability distribution vector contains multiple parameters, and each parameter corresponds to the proportion of photon intensity in a specific energy range.

[0007] According to an embodiment of the present invention, determining the measured CT values ​​of multiple materials based on CT scans of reference materials includes: scanning the reference materials using CT equipment to obtain the original scan data of each material; wherein the reference materials include multiple materials with known densities and elemental mass percentages; reconstructing the original scan data to obtain CT images of each material; and determining the measured CT values ​​of multiple materials based on the CT images.

[0008] According to an embodiment of the present invention, determining the measured CT values ​​of multiple materials based on CT images includes: determining the measured CT values ​​of the materials based on the material's attenuation coefficient, photon energy, electron density, and atomic number.

[0009] According to an embodiment of the present invention, the free parameters in the energy spectrum shape function are determined based on the measured CT values ​​of various materials to obtain the energy spectrum shape corresponding to the CT device. The method includes: calculating the theoretical CT value of each material based on the energy spectrum shape function, wherein the theoretical CT value contains free parameters; determining the target value of the free parameters by minimizing the difference between the theoretical CT value and the measured CT value; and substituting the target value into the energy spectrum shape function to obtain the energy spectrum shape information of the CT device.

[0010] According to an embodiment of the present invention, the target value of the free parameter is determined by minimizing the difference between the theoretical CT value and the measured CT value, including: constructing a target function based on the theoretical CT value and the measured CT value; adjusting the value of the free parameter through an optimization algorithm and calculating the target function value after each adjustment; and determining the value of the free parameter corresponding to the current target function as the target value when the target function value reaches the minimum value.

[0011] According to a second aspect of the present invention, a CT equipment calibration apparatus based on energy spectrum shape is provided, comprising: a construction module for constructing an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters for describing the energy spectrum distribution characteristics; a scanning module for scanning a reference material based on the CT equipment to obtain measured CT values ​​for various materials, wherein the reference material includes various materials with known densities and elemental mass percentages; and a determination module for determining the free parameters in the energy spectrum shape function based on the measured CT values ​​for various materials to obtain energy spectrum shape information of the CT equipment.

[0012] According to a third aspect of the present invention, an electronic device is provided, comprising: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0013] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0014] According to a fifth aspect of the present invention, a computer program product is also provided, comprising a computer program or instructions that, when executed by a processor, implement the steps of the above-described method. Attached Figure Description

[0015] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0016] Figure 1 A flowchart illustrating a CT equipment calibration method based on energy spectrum shape according to an embodiment of the present invention is shown schematically;

[0017] Figure 2 This schematically illustrates a flowchart of determining the measured CT values ​​of various materials by scanning reference materials with a CT device according to an embodiment of the present invention.

[0018] Figure 3 This schematically illustrates a flowchart of determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials according to an embodiment of the present invention, thereby obtaining the energy spectrum shape corresponding to the CT device.

[0019] Figure 4 A schematic diagram of the energy spectrum shape curve according to an embodiment of the present invention is shown.

[0020] Figure 5 A schematic diagram illustrating the structure of a CT equipment calibration apparatus based on energy spectrum shape according to an embodiment of the present invention is shown.

[0021] Figure 6 A block diagram of an electronic device for a CT device calibration method based on energy spectrum shape according to an embodiment of the present invention is shown schematically. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of a feature, step, operation, and / or component, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In the description of this invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses should not be construed as limiting.

[0027] Similarly, to simplify the invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] This invention provides a CT equipment calibration method, apparatus, device, medium, and program product based on energy spectrum shape. Before introducing the technical solution provided by this invention, the related technologies involved in this invention will be described first.

[0030] Existing CT equipment calibration methods employ chemometric calibration.

[0031] The calibration principle of this method is as follows: the CT value of a certain material ( ) and its attenuation coefficient ( The relationship between them is expressed based on the following formula:

[0032] ,in It is the attenuation coefficient of water;

[0033] Considering the physical process of photon-matter interaction, the attenuation coefficient The approximate calculation consists of three parts: the Klein-Nishina term (KN), the scattering term (sca), and the photoelectric effect term (ph), as shown in the following formula.

[0034]

[0035] in For the density of the substance, Let Avogadro's constant be 1. This represents the substances contained in the substance. Elements , , Representing the first Atomic number, mass number, and mass percentage of each element. , , These are free parameters and need to be determined by fitting the measurement data.

[0036] The specific steps of this method are as follows: Select a calibration phantom, which usually contains multiple materials, and the density and mass percentage of each material are known; obtain the (average) CT value of each material through CT scanning; and fit the free parameters in the model by combining the CT values ​​and element density distribution of different materials in the phantom with the formula in the model, thereby determining the energy spectrum information.

[0037] As can be seen from the formula for calculating the attenuation coefficient, the atomic number, mass number, and mass percentage of an element all affect the attenuation coefficient. Since different phantom materials contain different types of elements and different mass percentages, the attenuation coefficients calculated based on different phantom materials are different, which leads to different free parameters determined based on different phantom materials, thus affecting the stability of the energy spectrum information.

[0038] This method is somewhat dependent on the material of the calibration phantom. That is, under the same equipment, the free parameters obtained will change after changing the calibration phantom. For example, the energy spectrum parameters determined by scanning different phantoms with the same CT equipment will be different, which will lead to errors in the CT equipment calibration and thus affect the subsequent application effect.

[0039] This invention proposes a CT equipment calibration method based on energy spectrum shape, comprising: constructing an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters for describing the energy spectrum distribution characteristics; obtaining measured CT values ​​of various materials based on CT equipment scanning reference materials, wherein the reference materials include various materials with known densities and elemental mass percentages; determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials, thereby obtaining the energy spectrum shape corresponding to the CT equipment.

[0040] Figure 1 A flowchart illustrating a CT device calibration method based on energy spectrum shape according to an embodiment of the present invention is shown.

[0041] like Figure 1 As shown, the CT equipment calibration method based on energy spectrum shape in this embodiment includes operations S110 to S130.

[0042] In operation S110, an energy spectrum shape function is constructed based on the ray information, wherein the energy spectrum shape function includes free parameters used to describe the characteristics of the energy spectrum distribution.

[0043] In some embodiments, a parameterizable probability density function (PDF) can be selected to describe the shape of the energy spectrum, constructing an energy spectrum shape function. This energy spectrum shape function describes the distribution of the X-ray energy spectrum at different energies. For example, in CT equipment, the X-ray energy spectrum shapes generated at different tube voltages vary. The energy spectrum shape function can quantify this difference, providing a basis for accurate equipment calibration.

[0044] In some embodiments, the energy spectrum shape function can be a parameterized function such as a Gaussian function or a beta function, and the parameters in the function can reflect the peak position, width, symmetry and other characteristics of the energy spectrum.

[0045] For example, taking the energy spectrum shape function as a β function, the expression for the energy spectrum shape function S(E) of X-rays is:

[0046]

[0047] Among them, E min E represents the lowest energy threshold in the X-ray spectrum, typically taken as 20 keV; max It is the highest energy in the X-ray energy spectrum, mainly determined by the tube voltage of the CT equipment, and is usually around 100~120 keV; and These are free parameters. Used to control the slope on the left side of the energy spectrum, determining the shape characteristics of the energy spectrum in the low-energy region; The slope used to control the right side of the energy spectrum determines the shape of the energy spectrum in the high-energy region. (By...) and It can reflect the "softness" and "hardness" of the energy spectrum. A "soft" energy spectrum refers to a larger proportion of X-rays in the low-energy region, meaning the spectrum is relatively "broad" and has high intensity in the low-energy area. A "hard" energy spectrum refers to a dominant position of X-rays in the high-energy region, meaning the spectrum is relatively "broad" and has high intensity in the high-energy area.

[0048] For example, taking the energy spectrum shape function as a partial Gaussian function, the expression for the energy spectrum shape function S(E) of X-rays is:

[0049]

[0050] in It is a standard Gaussian distribution. It is a Gaussian cumulative distribution. It is the skew factor (which determines which side the energy spectrum is skewed towards). These are the mean and standard deviation. In this expression, , , These are free parameters and can be adjusted. , , To distinguish the peak value, width, and skewness of the energy spectrum. This energy spectrum shape function is applicable when E < 20 keV and... >The energy corresponding to the voltage of the CT equipment (e.g., 120kVp corresponds to 120keV) is 0.

[0051] It should be noted that although this invention only lists the β function and the partial Gaussian function as energy spectrum shape functions, it does not mean that energy spectrum shape functions are limited to these two probability density functions. Other forms of probability density functions as energy spectrum shape functions should also be included within the scope of protection of this invention.

[0052] During operation S120, the reference materials are scanned using CT equipment to obtain the measured CT values ​​of various materials. The reference materials include various materials with known densities and elemental mass percentages.

[0053] In some embodiments, a CT scanner is used to scan a reference material to obtain scan data. Combining the physical properties of the reference material with the energy spectrum information of the radiation, the attenuation coefficient of the material for photons of various energies is calculated from the scan data. A weighted integral is then performed based on the proportion of photons of each energy in the energy spectrum to obtain the average attenuation coefficient of the material. Based on the relationship between the average attenuation coefficient and the CT value, the measured CT values ​​for various materials are calculated.

[0054] For example, the reference material can be a known standard phantom. For instance, information such as the elemental density distribution and total density of the reference material is known. For example, the reference material can be a Gammex phantom, a CIRS phantom, etc.

[0055] In operation S130, the free parameters in the energy spectrum shape function are determined based on the measured CT values ​​of various materials, and the energy spectrum shape corresponding to the CT device is obtained.

[0056] In some embodiments, the difference between the measured and calculated CT values ​​can be fitted using the least squares method to determine the free parameters in the energy spectrum shape function and obtain the energy spectrum shape corresponding to the CT device.

[0057] This invention directly uses the energy spectrum shape function as the modeling object, and describes the overall distribution characteristics of the energy spectrum through free parameters. The energy spectrum shape is an inherent characteristic of the CT equipment itself and is independent of the material of the scanned object (phantom). Regardless of the type of phantom being scanned, the shape of the X-ray energy spectrum emitted by the equipment is fixed. The energy spectrum is modulated only by the phantom material, that is, different materials have different attenuation degrees for photons of different energies.

[0058] In this invention, the phantom material, by providing a known attenuation coefficient, converts the energy spectrum shape into CT values. Its role is to optimize the accuracy of the energy spectrum shape, rather than participating in its definition. For example, regardless of whether water or bone is scanned, the energy spectrum shape parameters (α, β) remain constant, but the CT values ​​will vary due to differences in material attenuation characteristics. In other words, the CT equipment calibration method provided by this invention effectively decouples the phantom material from the energy spectrum shape, reducing dependence on the phantom material during CT equipment calibration and thus effectively improving the accuracy of CT equipment calibration.

[0059] According to an embodiment of the present invention, after constructing the energy spectrum shape function, the method further includes: discretizing the energy spectrum shape function based on the energy range to obtain a discretized probability distribution vector, wherein the probability distribution vector contains multiple parameters, and each parameter corresponds to the proportion of photon intensity in a specific energy range.

[0060] In some embodiments, the energy range [E] min E max Divide the area evenly into n intervals, each interval having a width of ΔE = (E... max -E min For example, ΔE can be 1 keV (or 2 keV…10 keV). Alternatively, a non-equal-width partitioning method can be used, dynamically adjusting the interval width based on energy spectrum characteristics (such as characteristic peak positions); this invention does not limit this. The discretized probability distribution vector includes multiple parameters, each corresponding to a discretized energy spectrum value for an energy interval. This parameter describes the relative intensity distribution of X-ray photons within a specific range.

[0061] By discretizing the energy spectrum shape function, the energy distribution of X-ray photons can be effectively described. The relative proportions of photons with different energies can be quantified using the discretized parameters, which helps to support the subsequent calculation of material attenuation coefficients and quantitative calculation of CT values.

[0062] Figure 2 The flowchart illustrating the determination of measured CT values ​​for various materials by scanning reference materials using a CT scanner according to an embodiment of the present invention is shown.

[0063] like Figure 2 As shown, in this embodiment of the invention, scanning reference materials with a CT device to determine the measured CT values ​​of various materials includes operations S210 to S230.

[0064] In operation S210, a CT scanner is used to scan reference materials to obtain raw scan data for each of the multiple materials; among them, the reference materials include various materials with known densities and elemental mass percentages.

[0065] In some embodiments, appropriate CT scanning parameters are selected based on the phantom size, material properties, etc., and the reference material is scanned to obtain the original scanning data of multiple materials. The original scanning data is a series of projection data that can reflect the attenuation of X-rays after passing through the object.

[0066] In operation S220, the original scan data is reconstructed to obtain CT images of each material.

[0067] In some embodiments, the original scan data is converted into an image with a spatial distribution through an image reconstruction process, in which each pixel corresponds to a CT value. The CT value is a relative value used to quantify the degree to which tissue or material absorbs X-rays.

[0068] In operation S230, the measured CT values ​​of multiple materials are determined based on CT images.

[0069] In some embodiments, the region where each material sample is located is determined on the reconstructed CT image, and the average CT value of all pixels in that region is calculated. This average value is the measured CT value of the material.

[0070] For example, the measured CT value of a material can be determined based on its attenuation coefficient, photon energy, electron density, and atomic number. The expression for the material's attenuation coefficient μ is as follows:

[0071]

[0072] Where E is the photon energy. Z is the electron density of the material, and Z is the atomic number. It is the physical / mass density, A is the mass number, and r is the mass number. e =2.81794fm is the electrostatic electron diameter, N A It is Avogadro's constant. It is the scattering cross section of the photoelectric effect. It is the Compton scattering cross section. It refers to the scattering cross section that produces the effect.

[0073] , , The expression is as follows:

[0074] ;

[0075] ;

[0076]

[0077] Furthermore, the expression for the average attenuation of the material in the X-ray spectrum can be estimated as follows:

[0078]

[0079] in, This represents the relative size of the i-th energy range in the energy spectrum.

[0080] The formula for defining CT value is:

[0081]

[0082] Where H represents the CT value, and μ represents the attenuation coefficient of the material. This represents the attenuation coefficient of water.

[0083] After calculating the average attenuation (i.e., attenuation coefficient μ) of the material in the X-ray spectrum, the CT value of the material can be determined based on the relationship between the CT value and the attenuation coefficient, thus obtaining the measured CT value of the material.

[0084] Figure 3 The flowchart illustrates a process for determining the free parameters in the energy spectrum shape function based on measured CT values ​​of various materials according to an embodiment of the present invention, thereby obtaining the energy spectrum shape corresponding to the CT device.

[0085] like Figure 3 As shown, the free parameters in the energy spectrum shape function are determined based on the measured CT values ​​of various materials to obtain the energy spectrum shape corresponding to the CT device, including operations S310 to S330.

[0086] In operation S310, the theoretical CT value of each material is calculated based on the energy spectrum shape function, where the theoretical CT value includes free parameters.

[0087] In some embodiments, the linear attenuation coefficient of the material for X-rays of different energies E is calculated using relevant physical formulas based on the energy spectrum shape function and the material's physical properties (such as atomic number Z, density ρ, etc.). The theoretical CT value of the material is then determined based on the linear attenuation coefficient.

[0088] In operating S320, the target value of the free parameter is determined by minimizing the difference between the theoretical CT value and the measured CT value.

[0089] In some embodiments, the free parameters can be determined using the least squares method. A least squares objective function is constructed, and partial derivatives are calculated with respect to each free parameter to obtain the corresponding equation for each parameter. Based on the equations for each free parameter, a system of equations is derived. Solving this system of equations, the global minimum point of the objective function is found in the parameter space, yielding the values ​​of the free parameters. The free parameter values ​​corresponding to this global minimum point enable the energy spectrum shape function to most accurately fit the actual X-ray energy spectrum, providing the most accurate energy spectrum information for CT imaging, thereby improving image quality and the accuracy of material identification. For example, an iterative algorithm can be used to solve the above system of equations.

[0090] For example, operation S310 may include: constructing an objective function based on theoretical CT values ​​and measured CT values; adjusting the values ​​of free parameters through an optimization algorithm and calculating the objective function value after each adjustment; and determining the value of the free parameter corresponding to the current objective function as the objective value when the objective function value reaches its minimum value.

[0091] In operation S330, the values ​​of the free parameters are substituted into the energy spectrum shape function to obtain the energy spectrum shape function corresponding to the CT equipment.

[0092] In some embodiments, the values ​​of the free parameters determined by the least squares method are substituted into the energy spectrum shape function to obtain the target energy spectrum shape function of the CT device. The target energy spectrum shape function is used to accurately describe the distribution of the X-ray energy spectrum generated by the CT device.

[0093] In some embodiments, by substituting the target value of the optimized free function into the discretized energy spectrum shape, a discretized probability distribution vector describing the proportion of photon intensity in each energy range of the CT device's energy spectrum can be obtained. Combined with the energy range division information, the complete energy spectrum shape information of the CT device can be obtained.

[0094] Figure 4 A schematic diagram of the energy spectrum shape curve according to an embodiment of the present invention is shown.

[0095] See Figure 4 , Figure 4 The vertical axis represents the relative photon number, and the horizontal axis represents the energy. Figure 4 The energy spectrum shape information of the X-ray energy spectrum of a CT device at 120 keV is described when the β function is used as the energy spectrum shape function.

[0096] Based on the above-described CT equipment calibration method based on energy spectrum shape, this invention also provides a CT equipment calibration device based on energy spectrum shape. The following will be combined with... Figure 5 The device is described in detail.

[0097] Figure 5 A schematic diagram of a CT equipment calibration apparatus based on energy spectrum shape according to an embodiment of the present invention is shown.

[0098] like Figure 5 As shown, the CT equipment calibration device 500 based on energy spectrum shape in this embodiment includes a construction module 510, a scanning module 520, and a determination module 530.

[0099] The construction module 510 is used to construct an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters for describing the characteristics of the energy spectrum distribution. In one embodiment, the construction module 510 can be used to perform the operation S110 described above, which will not be repeated here.

[0100] The scanning module 520 is used to scan reference materials based on CT equipment to obtain the measured CT values ​​of various materials. The reference materials include various materials with known densities and elemental mass percentages. In one embodiment, the scanning module 520 can be used to perform the operation S120 described above, which will not be repeated here.

[0101] The determination module 530 is used to determine the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials, thereby obtaining the energy spectrum shape information of the CT device. In one embodiment, the determination module 530 can be used to perform the operation S130 described above, which will not be repeated here.

[0102] According to embodiments of the present invention, any plurality of modules among the construction module 510, scanning module 520, and determination module 530 may be combined into one module, or any one of these modules may be split into multiple modules. Alternatively, at least a portion of the functionality of one or more of these modules may be combined with at least a portion of the functionality of other modules and implemented in one module. According to embodiments of the present invention, at least one of the construction module 510, scanning module 520, and determination module 530 may be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging circuitry, or implemented in software, hardware, or firmware, or in any appropriate combination of any of these three implementation methods. Alternatively, at least one of the construction module 510, scanning module 520, and determination module 530 may be at least partially implemented as a computer program module, which, when run, can perform corresponding functions.

[0103] Figure 6 A block diagram of an electronic device for a CT device calibration method based on energy spectrum shape according to an embodiment of the present invention is shown schematically.

[0104] like Figure 6As shown, an electronic device 600 according to an embodiment of the present invention includes a processor 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage portion 608 into a random access memory (RAM) 603. The processor 601 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 601 may also include onboard memory for caching purposes. The processor 601 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0105] RAM 603 stores various programs and data required for the operation of electronic device 600. Processor 601, ROM 602, and RAM 603 are interconnected via bus 604. Processor 601 executes various operations of the method flow according to embodiments of the present invention by executing programs in ROM 602 and / or RAM 603. It should be noted that the program may also be stored in one or more memories other than ROM 602 and RAM 603. Processor 601 may also execute various operations of the method flow according to embodiments of the present invention by executing programs stored in one or more memories.

[0106] According to an embodiment of the present invention, the electronic device 600 may further include an input / output (I / O) interface 605, which is also connected to a bus 604. The electronic device 600 may also include one or more of the following components connected to the input / output (I / O) interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the input / output (I / O) interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 610 as needed so that computer programs read from it can be installed into the storage section 608 as needed.

[0107] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present invention.

[0108] According to embodiments of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including, but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of the present invention, a computer-readable storage medium may include ROM 602 and / or RAM 603 and / or one or more memories other than ROM 602 and RAM 603 described above.

[0109] Embodiments of the present invention also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code is used to enable the computer system to implement the CT equipment calibration method based on energy spectrum shape provided in the embodiments of the present invention.

[0110] When the computer program is executed by the processor 601, it performs the functions defined in the system / apparatus of this invention. According to embodiments of the invention, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0111] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and downloaded and installed via the communication section 609, and / or installed from the removable medium 611. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0112] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 609, and / or installed from the removable medium 611. When the computer program is executed by the processor 601, it performs the functions defined in the system of this embodiment of the invention. According to embodiments of the invention, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0113] According to embodiments of the present invention, program code for executing the computer programs provided in the embodiments of the present invention can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0114] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0115] Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention can be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0116] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A CT equipment calibration method based on energy spectrum shape, characterized in that, include: A spectrum shape function is constructed based on X-ray information, wherein the spectrum shape function includes free parameters for describing the characteristics of the spectrum distribution; Based on the CT equipment scanning the reference material, the measured CT values ​​of various materials are obtained. The reference material is a known standard phantom, including various materials with known density and element mass percentage. The free parameters in the energy spectrum shape function are determined based on the measured CT values ​​of various materials to obtain the energy spectrum shape information of the CT device. The free parameters in the energy spectrum shape function do not change with the material. For different materials, the free parameters remain unchanged to achieve decoupling between the energy spectrum shape and the material. The step of determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials to obtain the energy spectrum shape corresponding to the CT device includes: calculating the theoretical CT value of each material based on the energy spectrum shape function, wherein the theoretical CT value includes free parameters; determining the target value of the free parameters by minimizing the difference between the theoretical CT value and the measured CT value; and substituting the target value into the energy spectrum shape function to obtain the energy spectrum shape information of the CT device. The energy spectrum shape function is a parameterizable probability density function used to describe the distribution of the X-ray energy spectrum at different energies. The parameters in the energy spectrum shape function are used to reflect the peak position, width, and symmetry characteristics of the energy spectrum.

2. The CT equipment calibration method according to claim 1, characterized in that, Also includes: The energy spectrum shape function is discretized based on the energy range to obtain a discretized probability distribution vector. The probability distribution vector contains multiple parameters, each of which corresponds to the proportion of photon intensity in a specific energy range.

3. The CT equipment calibration method according to claim 1, characterized in that, The determination of measured CT values ​​for various materials based on the CT scan reference material includes: The CT equipment is used to scan the reference material to obtain the original scan data of each material; wherein, the reference material includes a variety of materials with known density and elemental mass percentage; The original scan data is reconstructed to obtain CT images of each material. The measured CT values ​​of multiple materials are determined based on the CT images.

4. The CT equipment calibration method according to claim 3, characterized in that, Determining the measured CT values ​​of each of the plurality of materials based on the CT images includes: The measured CT value of the material is determined based on its attenuation coefficient, photon energy, electron density, and atomic number.

5. The CT equipment calibration method according to claim 1, characterized in that, The process of minimizing the difference between theoretical and measured CT values ​​to determine the target values ​​of free parameters includes: A target function is constructed based on the theoretical CT values ​​and the measured CT values; The values ​​of the free parameters are adjusted by optimizing the algorithm, and the objective function value is calculated after each adjustment. When the objective function value reaches its minimum, the value of the free parameter corresponding to the current objective function is determined as the objective value.

6. A CT equipment calibration device based on energy spectrum shape, characterized in that, include: A construction module is used to construct an energy spectrum shape function based on X-ray information, wherein the energy spectrum shape function includes free parameters for describing the characteristics of the energy spectrum distribution; The scanning module is used to scan reference materials based on the CT equipment to obtain the measured CT values ​​of various materials. The reference materials are known standard phantoms, including various materials with known densities and elemental mass percentages. The determination module is used to determine the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials, thereby obtaining the energy spectrum shape information of the CT device. The free parameters in the energy spectrum shape function do not change with the material. For different materials, the free parameters remain unchanged, so as to achieve decoupling between the energy spectrum shape and the material. The step of determining the free parameters in the energy spectrum shape function based on the measured CT values ​​of various materials to obtain the energy spectrum shape corresponding to the CT device includes: calculating the theoretical CT value of each material based on the energy spectrum shape function, wherein the theoretical CT value contains free parameters; determining the target value of the free parameters by minimizing the difference between the theoretical CT value and the measured CT value; and substituting the target value into the energy spectrum shape function to obtain the energy spectrum shape information of the CT device. The energy spectrum shape function is a parameterizable probability density function used to describe the distribution of the X-ray energy spectrum at different energies, and the parameters in the energy spectrum shape function are used to reflect the peak position, width, and symmetry characteristics of the energy spectrum.

7. An electronic device, comprising: One or more processors; Memory, used to store one or more computer programs. The characteristic feature is that the one or more processors execute the one or more computer programs to implement the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1 to 5.

9. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1 to 5.

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