Energy threshold acquisition method and device for photon counter, and storage medium

Abstract

The present application discloses a method and apparatus, storage medium, and computer equipment for obtaining energy thresholds of a photon counter. The method comprises: obtaining the number of energy bins expected to be used in the photon counter, and determining multiple energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins; determining the material decomposition accuracy corresponding to each energy threshold combination using a material decomposition accuracy description model; and screening a target energy threshold combination from the multiple energy threshold combinations based on the material decomposition accuracy. The present application helps to improve the accuracy and efficiency of setting energy thresholds, thereby helping to improve the accuracy of multi-substance decomposition and the accuracy of multi-substance decomposition results.

Description

Technical Field

[0001] The present application relates to the field of photon counting technology, and in particular to a method and device for obtaining an energy threshold of a photon counter, a storage medium, and a computer device. Background Art

[0002] Photon counting CT divides the X-ray energy spectrum into N (N ≥ 2) energy bins. Each bin receives X-rays within a specific energy range, determined by the bin's energy threshold. Photon counting CT assigns each incident photon to a corresponding bin based on its energy. Each scan generates counts for multiple bins, meaning that photon counting CT can obtain information about an object across multiple X-ray energy ranges. Given that different elements have different attenuation coefficients at different X-ray energies, certain elements with k-edge properties (such as iodine, gadolinium, and gold contained in contrast agents) experience a sudden increase in their attenuation coefficients at specific X-ray energies. This sudden increase in attenuation coefficient results in a significant decrease in the photon counts for the corresponding bin. This property allows photon counting CT to achieve multi-substance decomposition (the number of decomposable substances is M, where 2 ≤ M ≤ N). The accuracy of multi-substance decomposition is influenced by the photon counts in the bin, and the bin energy threshold plays a crucial role in determining the number of photons received by the bin.

[0003] Currently, the energy thresholds of energy warehouses are mostly configured manually, and accuracy and efficiency are difficult to guarantee. Summary of the Invention

[0004] In view of this, the present application provides a method and device for obtaining the energy threshold of a photon counter, a storage medium, and a computer device.

[0005] According to one aspect of the present application, a method for obtaining an energy threshold of a photon counter is provided, comprising:

[0006] Obtaining a number of energy bins expected to be used in the photon counter, and determining a plurality of energy threshold combinations based on the number of energy bins and a preset threshold constraint, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins;

[0007] Determine the material decomposition accuracy corresponding to each energy threshold combination using a material decomposition accuracy description model;

[0008] A target energy threshold combination is screened from the plurality of energy threshold combinations according to the substance decomposition accuracy.

[0009] Optionally, the determining of multiple energy threshold combinations based on the number of energy bins and preset threshold constraints specifically includes:

[0010] Determining a plurality of energy threshold combinations based on the number of energy bins, the preset threshold constraint, and the preset energy threshold precision, so that the precision of each energy threshold in each energy threshold combination matches the preset energy threshold precision;

[0011] The preset threshold constraint condition includes at least one of a first constraint condition, a second constraint condition, a third constraint condition, and a fourth constraint condition. The first constraint condition is used to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter. The second constraint condition is used to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient. The third constraint condition is used to constrain any energy threshold in each energy threshold combination to match the k-edge energy value of any contrast agent element corresponding to the target scan object. The fourth constraint condition is used to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than a preset difference.

[0012] Optionally, before determining the material decomposition accuracy corresponding to each energy threshold combination using the material decomposition accuracy description model, the method further includes:

[0013] Constructing a Fisher information model based on the volume fractions of the multiple substances to be decomposed corresponding to the target scanning object, the attenuation coefficients at a preset energy, and the preset information contribution weights, wherein the substance decomposition accuracy description model includes the Fisher information model; and / or,

[0014] Constructing a decomposition matrix condition number model based on the incident spectrum of each energy bin and the attenuation path length corresponding to each substance to be decomposed, wherein the substance decomposition accuracy description model includes the decomposition matrix condition number model; and / or,

[0015] A virtual multi-substance decomposition model is constructed based on the substance concentrations corresponding to the multiple substances to be decomposed, wherein the substance decomposition accuracy description model includes the virtual multi-substance decomposition model.

[0016] Optionally, the method of using a material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each energy threshold combination specifically includes:

[0017] When the material decomposition accuracy description model includes the Fisher information model, respectively obtaining the energy bin energy spectrum corresponding to each energy threshold in each energy threshold combination, and determining the Fisher information value corresponding to each energy threshold combination according to the energy bin energy spectrum through the Fisher information model, wherein the material decomposition accuracy includes the Fisher information value; and / or,

[0018] When the material decomposition accuracy description model includes the decomposition matrix condition number model, the energy bin receiving energy range corresponding to each energy threshold in each energy threshold combination is obtained respectively, the attenuation coefficient curve of each material to be decomposed within the energy bin receiving energy range of each energy threshold combination is determined, and the condition number corresponding to each energy threshold combination is determined according to the attenuation coefficient curve through the decomposition matrix condition number model, wherein the material decomposition accuracy includes the condition number; and / or,

[0019] When the material decomposition accuracy description model includes the virtual multi-material decomposition model, the preset virtual model is scanned according to the preset spectrum by the virtual multi-material decomposition model to obtain a simulated output spectrum, and the energy bin count value corresponding to each of the energy threshold combinations is determined based on the simulated output spectrum, and the error between the energy bin count value corresponding to each of the energy threshold combinations and the theoretical count value of the preset virtual model is determined respectively, wherein the material decomposition accuracy includes the error.

[0020] Optionally, in the case where the material decomposition accuracy description model includes one, screening a target energy threshold combination from a plurality of energy threshold combinations based on the material decomposition accuracy specifically includes:

[0021] If the material decomposition accuracy description model is the Fisher information model, then obtaining the energy threshold combination corresponding to the maximum Fisher information value among the multiple energy threshold combinations as the target energy threshold combination;

[0022] If the material decomposition accuracy description model is the decomposition matrix condition number model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum condition number is obtained as the target energy threshold combination;

[0023] If the material decomposition accuracy description model is the virtual multi-material decomposition model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum error is obtained as the target energy threshold combination.

[0024] Optionally, in the case where the material decomposition accuracy description models include multiple ones, determining the material decomposition accuracy corresponding to each energy threshold combination by using the material decomposition accuracy description model specifically includes:

[0025] Determining the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model according to each material decomposition accuracy description model;

[0026] Accordingly, the step of screening a target energy threshold combination from the plurality of energy threshold combinations based on the substance decomposition accuracy specifically includes:

[0027] According to the material decomposition accuracy, respectively screening candidate energy threshold combinations corresponding to each material decomposition accuracy description model from the plurality of energy threshold combinations;

[0028] Based on the material decomposition accuracy of each energy threshold combination, an evaluation value of each candidate energy threshold combination corresponding to the material decomposition accuracy description model is calculated, and the target energy threshold combination is determined from the candidate energy threshold combinations through the evaluation value.

[0029] Optionally, after screening a target energy threshold combination from a plurality of energy threshold combinations based on the substance decomposition accuracy, the method further includes:

[0030] The energy threshold of each energy bin corresponding to the photon counter is configured according to the target energy threshold combination.

[0031] According to another aspect of the present application, a device for obtaining an energy threshold of a photon counter is provided, comprising:

[0032] a threshold determination module, configured to obtain a number of energy bins expected to be used in the photon counter, and determine a plurality of energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins;

[0033] An accuracy description module, configured to determine the material decomposition accuracy corresponding to each energy threshold combination by using a material decomposition accuracy description model;

[0034] A threshold screening module is used to screen a target energy threshold combination from the plurality of energy threshold combinations based on the material decomposition accuracy.

[0035] Optionally, the threshold determination module is specifically configured to:

[0036] Determining a plurality of energy threshold combinations based on the number of energy bins, the preset threshold constraint, and the preset energy threshold precision, so that the precision of each energy threshold in each energy threshold combination matches the preset energy threshold precision;

[0037] The preset threshold constraint condition includes at least one of a first constraint condition, a second constraint condition, a third constraint condition, and a fourth constraint condition. The first constraint condition is used to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter. The second constraint condition is used to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient. The third constraint condition is used to constrain any energy threshold in each energy threshold combination to match the k-edge energy value of any contrast agent element corresponding to the target scan object. The fourth constraint condition is used to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than a preset difference.

[0038] Optionally, the device further comprises: a model building module, configured to:

[0039] Before determining the material decomposition accuracy corresponding to each of the energy threshold combinations using the material decomposition accuracy description model, a Fisher information model is constructed based on the volume fractions of the multiple materials to be decomposed corresponding to the target scanning object, the attenuation coefficients at the preset energy, and the preset information contribution weights, wherein the material decomposition accuracy description model includes the Fisher information model; and / or,

[0040] Constructing a decomposition matrix condition number model based on the incident spectrum of each energy bin and the attenuation path length corresponding to each substance to be decomposed, wherein the substance decomposition accuracy description model includes the decomposition matrix condition number model; and / or,

[0041] A virtual multi-substance decomposition model is constructed based on the substance concentrations corresponding to the multiple substances to be decomposed, wherein the substance decomposition accuracy description model includes the virtual multi-substance decomposition model.

[0042] Optionally, the accuracy description module is specifically configured to:

[0043] When the material decomposition accuracy description model includes the Fisher information model, respectively obtaining the energy bin energy spectrum corresponding to each energy threshold in each energy threshold combination, and determining the Fisher information value corresponding to each energy threshold combination according to the energy bin energy spectrum through the Fisher information model, wherein the material decomposition accuracy includes the Fisher information value; and / or,

[0044] When the material decomposition accuracy description model includes the decomposition matrix condition number model, the energy bin receiving energy range corresponding to each energy threshold in each energy threshold combination is obtained respectively, the attenuation coefficient curve of each material to be decomposed within the energy bin receiving energy range of each energy threshold combination is determined, and the condition number corresponding to each energy threshold combination is determined according to the attenuation coefficient curve through the decomposition matrix condition number model, wherein the material decomposition accuracy includes the condition number; and / or,

[0045] When the material decomposition accuracy description model includes the virtual multi-material decomposition model, the preset virtual model is scanned according to the preset spectrum by the virtual multi-material decomposition model to obtain a simulated output spectrum, and the energy bin count value corresponding to each of the energy threshold combinations is determined based on the simulated output spectrum, and the error between the energy bin count value corresponding to each of the energy threshold combinations and the theoretical count value of the preset virtual model is determined respectively, wherein the material decomposition accuracy includes the error.

[0046] Optionally, when the substance decomposition accuracy description model includes one, the threshold screening module is specifically configured to:

[0047] If the material decomposition accuracy description model is the Fisher information model, then obtaining the energy threshold combination corresponding to the maximum Fisher information value among the multiple energy threshold combinations as the target energy threshold combination;

[0048] If the material decomposition accuracy description model is the decomposition matrix condition number model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum condition number is obtained as the target energy threshold combination;

[0049] If the material decomposition accuracy description model is the virtual multi-material decomposition model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum error is obtained as the target energy threshold combination.

[0050] Optionally, in the case where the material decomposition accuracy description model includes multiple models, the accuracy description module is further used to: determine the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model according to each material decomposition accuracy description model;

[0051] Correspondingly, the threshold screening module is also used to: based on the material decomposition accuracy, screen the candidate energy threshold combination corresponding to each material decomposition accuracy description model in the multiple energy threshold combinations; based on the material decomposition accuracy of each energy threshold combination, calculate the evaluation value of the candidate energy threshold combination corresponding to each material decomposition accuracy description model, and determine the target energy threshold combination in the candidate energy threshold combination through the evaluation value.

[0052] Optionally, the device further comprises:

[0053] A threshold configuration module is used to configure the energy thresholds of each energy bin corresponding to the photon counter according to the target energy threshold combination after screening a target energy threshold combination from the multiple energy threshold combinations based on the material decomposition accuracy.

[0054] According to another aspect of the present application, a storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the energy threshold acquisition method of the photon counter is implemented.

[0055] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein the processor implements the energy threshold acquisition method of the photon counter when executing the program.

[0056] By means of the above technical solution, the present application provides a method and device for obtaining an energy threshold of a photon counter, a storage medium, and a computer device. Multiple energy threshold combinations are generated based on preset threshold constraints. The number of energy thresholds in each combination is the same as the number of energy bins expected to be used in the photon counter. The pre-constructed material decomposition accuracy description model is then used to determine the material decomposition accuracy corresponding to each energy threshold combination, and the target energy threshold combination is screened out from the multiple combinations based on the material decomposition accuracy. The embodiment of the present application generates multiple energy threshold combinations that meet the conditions by setting preset threshold constraints, and constructs a material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each combination, so as to achieve the screening of the target energy threshold combination. Compared with the method of setting energy thresholds based on manual experience in the prior art, this method helps to improve the accuracy and efficiency of setting energy thresholds, thereby helping to improve the accuracy of multi-substance decomposition and the accuracy of multi-substance decomposition results.

[0057] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0059] Figure 1 A schematic diagram showing a flow chart of a method for obtaining an energy threshold of a photon counter provided in an embodiment of the present application is shown;

[0060] Figure 2 A schematic diagram of a preset virtual phantom provided in an embodiment of the present application is shown;

[0061] Figure 3 A schematic diagram of a virtual multi-substance decomposition process provided by an embodiment of the present application is shown;

[0062] Figure 4 A schematic structural diagram of an energy threshold acquisition device for a photon counter provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0063] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0064] In this embodiment, a method for obtaining the energy threshold of a photon counter is provided, such as Figure 1 As shown, the method includes:

[0065] Step 101: Obtain the number of energy bins expected to be used in the photon counter, and determine multiple energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins;

[0066] In the embodiments of the present application, a preset threshold constraint is pre-established to constrain the generation rules of energy threshold combinations. The preset threshold constraint can be set based on the parameters of the photon counter and the actual usage environment of the photon counter. Multiple energy threshold combinations are thus generated based on the constraint. In actual use, the photon counter can use all or some of the energy bins. Each energy threshold combination includes energy thresholds corresponding to the number of energy bins expected to be used in the photon counter. For example, if the photon counter includes N energy bins expected to be used, each energy threshold combination includes N energy thresholds.

[0067] In an embodiment of the present application, optionally, in step 101, "determining multiple energy threshold combinations based on the number of energy bins and the preset threshold constraint conditions" can specifically include: determining multiple energy threshold combinations based on the number of energy bins, the preset threshold constraint conditions and the preset energy threshold accuracy, so that the accuracy of each energy threshold in each energy threshold combination matches the preset energy threshold accuracy; wherein the preset threshold constraint conditions include at least one of a first constraint condition, a second constraint condition, a third constraint condition and a fourth constraint condition, the first constraint condition is used to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter, the second constraint condition is used to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient, the third constraint condition is used to constrain any energy threshold in each energy threshold combination to match the k-edge energy value of any contrast agent element corresponding to the target scan object, and the fourth constraint condition is used to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than the preset difference.

[0068] In the above embodiment, in order to reduce the number of energy threshold combinations, the accuracy of the energy threshold in each combination can be limited. For example, the accuracy of each energy threshold is limited to the unit digit, that is, the preset energy threshold accuracy is set to the unit digit. In conjunction with the pre-constructed preset threshold constraint conditions, the energy threshold combination can be generated by enumeration. Among them, the preset threshold constraint conditions can include at least one of the above constraints, taking the example of including all of the above constraints. The tube voltage of the photon counter can be obtained first, and the energy thresholds contained in each energy threshold combination can be described as: 0≤Th0≤…≤Th N-1 ≤ tube voltage, where Th x represents the energy threshold for the xth energy bin, which is the first constraint. Th0 can be set relatively large to filter out low-energy noise and reduce the effects of beam hardening. The minimum energy threshold Th0 is determined by the product of the tube voltage and a preset coefficient. For example, the value rounded to the preset energy threshold precision can be selected as the energy threshold Th0, which is the second constraint. If the scanned object includes a contrast agent, such as a CT scan of a human body after injection of a contrast agent, an energy threshold can be set near the k-edge energy value of the contrast agent element. For example, if the scanned object contains a gadolinium contrast agent (the k-edge of gadolinium is 50.2 keV), the energy threshold can be set to 50 keV (rounded to the preset energy threshold precision), which is the third constraint. Finally, to prevent image artifacts caused by a low number of photons received in an energy bin, adjacent energy thresholds should not be too close. The difference (or absolute value of the difference) between two adjacent energy thresholds can be constrained to be less than a preset difference, which is the fourth constraint.

[0069] The relationship between the energy threshold and the accuracy of the optimization target multi-substance decomposition is difficult to describe by a simple objective function, so the traditional optimization method is difficult to apply, and the intelligent optimization method is prone to fall into the local optimal solution. Therefore, the embodiment of the present application can use the enumeration method to generate energy threshold combinations. After the above constraints, the number of energy threshold combinations that meet the conditions will not be too large, so the enumeration method is feasible in terms of computational cost. For example, all energy threshold combinations that meet the constraints can be generated. Where s is the number of combinations. Furthermore, if the number of combinations that meet the constraints is too large or too small, the preset coefficient of the second constraint and the preset difference of the fourth constraint can be adjusted to reduce or increase the number of combinations that meet the constraints. For example, increasing the preset coefficient or preset difference can reduce the number of combinations that meet the constraints.

[0070] Step 102: using a material decomposition accuracy description model, determine the material decomposition accuracy corresponding to each energy threshold combination;

[0071] Step 103 : Screening a target energy threshold combination from the plurality of energy threshold combinations based on the substance decomposition accuracy.

[0072] To improve the multi-substance resolution accuracy of a photon counter, a pre-constructed material resolution accuracy description model is used to calculate the material resolution accuracy for each energy threshold combination. It should be noted that this material resolution accuracy is simulated by the description model and is used to screen energy threshold combinations, not the photon counter's actual multi-substance resolution accuracy. Material resolution accuracy description models can take various forms. For example, the multi-substance resolution problem can be considered a parameter estimation problem, where the unknown parameters to be estimated are the volume fractions of the various substances in the scanned object. Fisher information is a measure of the expected amount of information a single observation can provide about the unknown parameters. The greater the Fisher information, the more accurate the estimate of the unknown parameters, which translates to higher multi-substance resolution accuracy. Therefore, the Fisher information can be used as a basis for selecting energy threshold combinations. The material resolution accuracy for each combination is calculated by constructing a Fisher information model. Finally, after determining the material resolution accuracy for each energy threshold combination, the energy threshold combination with the highest resolution accuracy is selected from multiple energy threshold combinations as the final target energy threshold combination.

[0073] By applying the technical solution of this embodiment, multiple energy threshold combinations are generated based on preset threshold constraints. The number of energy thresholds in each combination is the same as the number of energy bins expected to be used in the photon counter. Then, the pre-constructed material decomposition accuracy description model is used to determine the material decomposition accuracy corresponding to each energy threshold combination, and the target energy threshold combination is screened out from the multiple combinations based on the material decomposition accuracy. The embodiment of the present application generates multiple energy threshold combinations that meet the conditions by setting preset threshold constraints, and constructs a material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each combination, so as to achieve the screening of the target energy threshold combination. Compared with the method of setting energy thresholds based on manual experience in the prior art, this method helps to improve the accuracy and efficiency of setting energy thresholds, thereby helping to improve the accuracy of multi-substance decomposition and the accuracy of multi-substance decomposition results.

[0074] In an embodiment of the present application, optionally, before executing step 102, it also includes constructing a material decomposition accuracy description model, which may specifically include: constructing a Fisher information model based on the volume fractions of the multiple materials to be decomposed corresponding to the target scanning object, the attenuation coefficients at the preset energy, and the preset information contribution weights, wherein the material decomposition accuracy description model includes the Fisher information model; and / or, constructing a decomposition matrix condition number model based on the incident spectrum of each energy bin and the attenuation path length corresponding to each material to be decomposed, wherein the material decomposition accuracy description model includes the decomposition matrix condition number model; and / or, constructing a virtual multi-material decomposition model based on the material concentrations corresponding to the multiple materials to be decomposed, wherein the material decomposition accuracy description model includes the virtual multi-material decomposition model.

[0075] In the above embodiments, three material decomposition accuracy description models are provided: the Fisher information model, the decomposition matrix condition number model, and the virtual multi-material decomposition model. The specific forms of these three models are described below. Furthermore, the material decomposition accuracy description models of the embodiments of this application are not limited to the following three forms; any model capable of describing the multi-material decomposition accuracy of a photon counter will suffice.

[0076] About the Fisher Information Model:

[0077] When the number of unknown parameters is greater than one, the Fisher information is represented by the Fisher information matrix, which is an M×M matrix in this embodiment. The calculation method of its αth row and βth column is as follows:

[0078]

[0079] Where A m represents the volume fraction of the mth substance to be decomposed, u m (E) is the attenuation coefficient of the mth substance to be decomposed under energy E, In0 Refers to the theoretical energy spectrum of the nth energy bin, which is determined based on the energy threshold of the energy field. V It can be obtained from the Fisher information matrix in the following way, where [w1,…,w M ] represents the information amount of each substance to be decomposed on F V Contribution weight, F V =[w1,…,w M ]*[F 11 ,…,F MM ] T .

[0080] Accordingly, when the material decomposition accuracy description model includes the Fisher information model, step 102 may specifically include:

[0081] Step 102-1, when the material decomposition accuracy description model includes the Fisher information model, respectively obtain the energy bin energy spectrum corresponding to each energy threshold in each energy threshold combination, and determine the Fisher information value corresponding to each energy threshold combination according to the energy bin energy spectrum through the Fisher information model, wherein the material decomposition accuracy includes the Fisher information value.

[0082] In this embodiment, for any energy threshold combination, the energy spectrum of each energy bin can be determined according to each energy threshold in the combination, and each energy bin energy spectrum is substituted into the above-mentioned Fisher information model, and the F is calculated based on the information content of each substance to be decomposed. V The contribution weight is used to calculate the corresponding Fisher information value F V The larger the Fisher information value, the higher the corresponding multi-substance decomposition accuracy.

[0083] About the decomposition matrix condition number model:

[0084] The image-domain-based multi-substance decomposition method is one of the multi-substance decomposition techniques for photon counting CT. Its essence is to solve a system of linear equations, and the decomposition matrix S is the coefficient matrix of the linear equations to be solved. From the knowledge of linear algebra, it is known that the condition number of the coefficient matrix can characterize the stability of the solution to the linear equation system. From the perspective of multi-substance decomposition, the condition number of the decomposition matrix represents the impact of image noise on the multi-substance decomposition results. The smaller the condition number, the less affected the decomposition results are by noise, and the higher the decomposition accuracy. The decomposition matrix S is an N×M decomposition matrix, representing the attenuation coefficients (or CT values) of M substances of known concentration in N bins under a given energy threshold. Based on this definition, the calculation method of the decomposition matrix is ​​given. The calculation formula for its αth row and βth column is as follows:

[0085]

[0086] Where Iα0 (E) represents the incident spectrum of the αth energy bin, u αβ (E) represents the attenuation coefficient curve of the β-th substance to be decomposed with known concentration within the α-th energy bin range (the energy bin range is determined according to the energy threshold of the energy bin), l β represents the attenuation path length of the β-th substance (which can be appropriately estimated based on the size of the scanned object). Thus, a model is constructed to solve the above decomposition matrix. The specific model can be constructed by referring to the condition number solution method in the prior art and is not limited here.

[0087] Accordingly, in the case where the material decomposition accuracy description model includes a decomposition matrix condition number model.

[0088] Step 102 may specifically include:

[0089] Step 102-2, when the material decomposition accuracy description model includes the decomposition matrix condition number model, respectively obtain the energy bin receiving energy range corresponding to each energy threshold in each energy threshold combination, determine the attenuation coefficient curve of each material to be decomposed within the energy bin receiving energy range of each energy threshold combination, and determine the condition number corresponding to each energy threshold combination according to the attenuation coefficient curve through the decomposition matrix condition number model, wherein the material decomposition accuracy includes the condition number.

[0090] In this embodiment, for any energy threshold combination, the energy threshold for each energy bin can be determined based on the energy thresholds in the combination. Furthermore, the attenuation coefficient curve for each substance to be decomposed within each energy bin range for a known concentration is determined, substituted into the decomposition matrix formula, and the condition number of the decomposition matrix is ​​calculated using the decomposition matrix condition number model. The smaller the condition number, the higher the corresponding multi-substance decomposition accuracy.

[0091] Virtual multi-material decomposition model:

[0092] Virtual multi-substance decomposition refers to the use of simulation methods to complete the imaging and material decomposition process of photon CT. With other conditions remaining unchanged, a virtual multi-substance decomposition is performed for each energy threshold combination to determine the number of photons received by each energy bin under the current energy threshold combination. A virtual phantom is constructed based on the preset concentrations of multiple substances to be decomposed. The virtual phantom is used as the scanned object. By running a simulation program (i.e., a virtual multi-substance decomposition model), the output spectrum of the preset spectrum after passing through the virtual phantom at each channel and angle is obtained. From the output spectrum, the photon count value for each energy bin at each channel and angle is obtained. This count value can be compared with the theoretical count value, and the comparison results are used to describe the accuracy of the multi-substance decomposition.

[0093] Accordingly, in the case where the material decomposition accuracy description model includes a virtual multi-material decomposition model.

[0094] Step 102 may specifically include:

[0095] Step 102-3, when the material decomposition accuracy description model includes the virtual multi-material decomposition model, the preset virtual model is scanned according to the preset spectrum through the virtual multi-material decomposition model to obtain a simulated output spectrum, and the energy bin count value corresponding to each of the energy threshold combinations is determined based on the simulated output spectrum, and the error between the energy bin count value corresponding to each of the energy threshold combinations and the theoretical count value of the preset virtual model is determined respectively, wherein the material decomposition accuracy includes the error.

[0096] In this embodiment, for any energy threshold combination, the virtual multi-substance decomposition model can be configured by determining the energy threshold of each energy bin according to each energy threshold in the combination. Figure 2 As shown in , a virtual phantom is generated based on the concentration of various substances contained in the scanned object. Figure 3 As shown, after the virtual model is generated, the simulation program is run to scan the virtual model according to the initial spectrum (i.e., the preset spectrum), and the output spectrum after passing through the virtual model is simulated. The count value of each energy bin is obtained from the simulated output spectrum, and the energy bin count value is compared with the corresponding theoretical value to determine the error between the two. The error is used to describe the accuracy of material decomposition. The smaller the error, the higher the corresponding accuracy.

[0097] In the embodiment of the present application, optionally, when the material decomposition accuracy description model includes one, step 103 may specifically include:

[0098] Step 103-1: If the material decomposition accuracy description model is the Fisher information model, then, among the multiple energy threshold combinations, the energy threshold combination corresponding to the maximum Fisher information value is obtained as the target energy threshold combination;

[0099] Step 103-2: If the material decomposition accuracy description model is the decomposition matrix condition number model, then, among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum condition number is obtained as the target energy threshold combination;

[0100] Step 103 - 3 : If the material decomposition accuracy description model is the virtual multi-material decomposition model, then from the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum error is obtained as the target energy threshold combination.

[0101] In this embodiment, the energy threshold combination with the largest Fisher information value can be used as the target energy threshold combination, or the energy threshold combination with the smallest condition number can be used as the target energy threshold combination, or the energy threshold combination with the smallest error can be used as the target energy threshold combination, so as to screen out a group of energy threshold combinations with the highest multi-substance decomposition accuracy from multiple energy threshold combinations.

[0102] In the embodiment of the present application, optionally, when the material decomposition accuracy description model includes multiple models, step 102 may specifically include: determining the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model according to each material decomposition accuracy description model;

[0103] Accordingly, step 103 may specifically include: based on the material decomposition accuracy, screening the candidate energy threshold combination corresponding to each material decomposition accuracy description model from the multiple energy threshold combinations; based on the material decomposition accuracy of each energy threshold combination, calculating the evaluation value of each candidate energy threshold combination corresponding to the material decomposition accuracy description model, and determining the target energy threshold combination from the candidate energy threshold combinations through the evaluation value.

[0104] In the above embodiment, multiple material decomposition accuracy description models can also be used to realize the screening of energy threshold combinations. Specifically, according to the methods of the above steps 102-1, 102-2, and 102-3, the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model can be calculated, and according to the material decomposition accuracy corresponding to each model, referring to the methods of steps 103-1, 103-2, and 103-3, the candidate energy threshold combination with the highest material decomposition accuracy corresponding to the model can be selected from multiple energy threshold combinations.

[0105] Furthermore, the material decomposition accuracy corresponding to each candidate energy threshold combination is calculated, and the evaluation value of the material decomposition accuracy of each of the multiple energy threshold combinations corresponding to the corresponding model is calculated. The candidate energy threshold combination with the highest evaluation value is selected as the final target energy threshold combination. For any material decomposition accuracy description model, the evaluation value of the candidate energy threshold combination can be the absolute value of P, where P = (material decomposition accuracy of the candidate energy threshold combination - average material decomposition accuracy of each energy threshold combination) / average material decomposition accuracy of each energy threshold combination.

[0106] In the embodiment of the present application, optionally, after step 103, the following steps may be further included:

[0107] Step 104 : configuring the energy threshold of each energy bin corresponding to the photon counter according to the target energy threshold combination.

[0108] In the above embodiment, after obtaining the target energy threshold combination of the photon counter, the energy threshold of each energy bin of the photon counter can also be configured according to the combination to realize the automatic setting of the energy bin parameters of the photon counter. Combined with the above content of the embodiment of the present application, the effect of automatically configuring the energy threshold of the energy bin of the photon counter according to the set tube voltage can be achieved.

[0109] Further, as Figure 1 The specific implementation of the method, the embodiment of the present application provides an energy threshold acquisition device for a photon counter, such as Figure 4 As shown, the device includes:

[0110] a threshold determination module, configured to obtain a number of energy bins expected to be used in the photon counter, and determine a plurality of energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins;

[0111] An accuracy description module, configured to determine the material decomposition accuracy corresponding to each energy threshold combination by using a material decomposition accuracy description model;

[0112] A threshold screening module is used to screen a target energy threshold combination from the plurality of energy threshold combinations based on the material decomposition accuracy.

[0113] Optionally, the threshold determination module is specifically configured to:

[0114] Determining a plurality of energy threshold combinations based on the number of energy bins, the preset threshold constraint, and the preset energy threshold precision, so that the precision of each energy threshold in each energy threshold combination matches the preset energy threshold precision;

[0115] The preset threshold constraint condition includes at least one of a first constraint condition, a second constraint condition, a third constraint condition, and a fourth constraint condition. The first constraint condition is used to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter. The second constraint condition is used to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient. The third constraint condition is used to constrain any energy threshold in each energy threshold combination to match the k-edge energy value of any contrast agent element corresponding to the target scan object. The fourth constraint condition is used to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than a preset difference.

[0116] Optionally, the device further comprises: a model building module, configured to:

[0117] Before determining the material decomposition accuracy corresponding to each of the energy threshold combinations using the material decomposition accuracy description model, a Fisher information model is constructed based on the volume fractions of the multiple materials to be decomposed corresponding to the target scanning object, the attenuation coefficients at the preset energy, and the preset information contribution weights, wherein the material decomposition accuracy description model includes the Fisher information model; and / or,

[0118] Constructing a decomposition matrix condition number model based on the incident spectrum of each energy bin and the attenuation path length corresponding to each substance to be decomposed, wherein the substance decomposition accuracy description model includes the decomposition matrix condition number model; and / or,

[0119] A virtual multi-substance decomposition model is constructed based on the substance concentrations corresponding to the multiple substances to be decomposed, wherein the substance decomposition accuracy description model includes the virtual multi-substance decomposition model.

[0120] Optionally, the accuracy description module is specifically configured to:

[0121] When the material decomposition accuracy description model includes the Fisher information model, respectively obtaining the energy bin energy spectrum corresponding to each energy threshold in each energy threshold combination, and determining the Fisher information value corresponding to each energy threshold combination according to the energy bin energy spectrum through the Fisher information model, wherein the material decomposition accuracy includes the Fisher information value; and / or,

[0122] When the material decomposition accuracy description model includes the decomposition matrix condition number model, the energy bin receiving energy range corresponding to each energy threshold in each energy threshold combination is obtained respectively, the attenuation coefficient curve of each material to be decomposed within the energy bin receiving energy range of each energy threshold combination is determined, and the condition number corresponding to each energy threshold combination is determined according to the attenuation coefficient curve through the decomposition matrix condition number model, wherein the material decomposition accuracy includes the condition number; and / or,

[0123] When the material decomposition accuracy description model includes the virtual multi-material decomposition model, the preset virtual model is scanned according to the preset spectrum by the virtual multi-material decomposition model to obtain a simulated output spectrum, and the energy bin count value corresponding to each of the energy threshold combinations is determined based on the simulated output spectrum, and the error between the energy bin count value corresponding to each of the energy threshold combinations and the theoretical count value of the preset virtual model is determined respectively, wherein the material decomposition accuracy includes the error.

[0124] Optionally, when the substance decomposition accuracy description model includes one, the threshold screening module is specifically configured to:

[0125] If the material decomposition accuracy description model is the Fisher information model, then obtaining the energy threshold combination corresponding to the maximum Fisher information value among the multiple energy threshold combinations as the target energy threshold combination;

[0126] If the material decomposition accuracy description model is the decomposition matrix condition number model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum condition number is obtained as the target energy threshold combination;

[0127] If the material decomposition accuracy description model is the virtual multi-material decomposition model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum error is obtained as the target energy threshold combination.

[0128] Optionally, in the case where the material decomposition accuracy description model includes multiple models, the accuracy description module is further used to: determine the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model according to each material decomposition accuracy description model;

[0129] Correspondingly, the threshold screening module is also used to: based on the material decomposition accuracy, screen the candidate energy threshold combination corresponding to each material decomposition accuracy description model in the multiple energy threshold combinations; based on the material decomposition accuracy of each energy threshold combination, calculate the evaluation value of the candidate energy threshold combination corresponding to each material decomposition accuracy description model, and determine the target energy threshold combination in the candidate energy threshold combination through the evaluation value.

[0130] Optionally, the device further comprises:

[0131] A threshold configuration module is used to configure the energy thresholds of each energy bin corresponding to the photon counter according to the target energy threshold combination after screening a target energy threshold combination from the multiple energy threshold combinations based on the material decomposition accuracy.

[0132] It should be noted that for other corresponding descriptions of the functional units involved in the energy threshold acquisition device of a photon counter provided in the embodiment of the present application, reference can be made to Figures 1 to 3 The corresponding description in the method will not be repeated here.

[0133] Based on the above Figures 1 to 3 The method shown in FIG. 1 is a method for performing the above-mentioned operation. Accordingly, the embodiment of the present application further provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned operation is performed. Figures 1 to 3 The energy threshold acquisition method of the photon counter is shown.

[0134] Based on this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, USB flash drive, mobile hard disk, etc.), including a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each implementation scenario of the present application.

[0135] Based on the above Figures 1 to 3 The method shown, and Figure 4 In order to achieve the above-mentioned purpose, the embodiment of the present application further provides a computer device, which can be a personal computer, a server, a network device, etc. The computer device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to achieve the above-mentioned Figures 1 to 3 The energy threshold acquisition method of the photon counter is shown.

[0136] Optionally, the computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, a sensor, an audio circuit, a Wi-Fi module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a Wi-Fi interface), etc.

[0137] Those skilled in the art will understand that the computer device structure provided in this embodiment does not constitute a limitation on the computer device, and may include more or fewer components, or a combination of certain components, or different component arrangements.

[0138] The storage medium may also include an operating system and a network communication module. An operating system is a program that manages and stores the hardware and software resources of a computer device, supporting the execution of information processing programs and other software and / or programs. The network communication module facilitates communication between components within the storage medium, as well as with other hardware and software within the physical device.

[0139] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented by means of software plus the necessary general hardware platform, or by hardware implementation to generate multiple energy threshold combinations based on preset threshold constraints, the number of energy thresholds in each combination being the same as the number of energy bins expected to be used in the photon counter, and then using the pre-constructed material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each energy threshold combination, and to screen out the target energy threshold combination from the multiple combinations based on the material decomposition accuracy. The embodiment of the present application generates multiple energy threshold combinations that meet the conditions by setting preset threshold constraints, and constructs a material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each combination, so as to achieve the screening of the target energy threshold combination. Compared with the method of setting energy thresholds based on manual experience in the prior art, it helps to improve the accuracy and efficiency of setting energy thresholds, and thus helps to improve the accuracy of multi-substance decomposition and the accuracy of multi-substance decomposition results.

[0140] Those skilled in the art will understand that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily required to implement the present application. Those skilled in the art will understand that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the implementation scenario description, or can be changed accordingly and located in one or more devices different from the implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0141] The serial numbers of the above application are for descriptive purposes only and do not represent the advantages or disadvantages of the implementation scenarios. The above disclosure only discloses several specific implementation scenarios of the present application, but the present application is not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present application.

Claims

1. A method for obtaining an energy threshold of a photon counter, characterized in that: include: Obtaining the number of energy bins expected to be used in the photon counter, and determining multiple energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins, and the preset threshold constraints include at least one of a first constraint, a second constraint, a third constraint, and a fourth constraint, wherein the first constraint is used to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter, the second constraint is used to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient, the third constraint is used to constrain any energy threshold in each energy threshold combination to match a k-edge energy value of any contrast agent element corresponding to a target scan object, and the fourth constraint is used to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than a preset difference; Determine the material decomposition accuracy corresponding to each energy threshold combination using a material decomposition accuracy description model; A target energy threshold combination is screened from the plurality of energy threshold combinations according to the substance decomposition accuracy.

2. The method according to claim 1, characterized in that Determining multiple energy threshold combinations based on the number of energy bins and preset threshold constraints specifically includes: Based on the number of energy bins, the preset threshold constraint condition and the preset energy threshold accuracy, a plurality of energy threshold combinations are determined so that the accuracy of each energy threshold in each energy threshold combination matches the preset energy threshold accuracy.

3. The method according to claim 1, characterized in that Before determining the material decomposition accuracy corresponding to each energy threshold combination using the material decomposition accuracy description model, the method further includes: Constructing a Fisher information model based on the volume fractions of the multiple substances to be decomposed corresponding to the target scanning object, the attenuation coefficients at a preset energy, and the preset information contribution weights, wherein the substance decomposition accuracy description model includes the Fisher information model; and / or, Constructing a decomposition matrix condition number model based on the incident spectrum of each energy bin and the attenuation path length corresponding to each substance to be decomposed, wherein the substance decomposition accuracy description model includes the decomposition matrix condition number model; and / or, A virtual multi-substance decomposition model is constructed based on the substance concentrations corresponding to the multiple substances to be decomposed, wherein the substance decomposition accuracy description model includes the virtual multi-substance decomposition model.

4. The method according to claim 3, characterized in that The method of using the material decomposition accuracy description model to determine the material decomposition accuracy corresponding to each energy threshold combination specifically includes: When the material decomposition accuracy description model includes the Fisher information model, respectively obtaining the energy bin energy spectrum corresponding to each energy threshold in each energy threshold combination, and determining the Fisher information value corresponding to each energy threshold combination according to the energy bin energy spectrum through the Fisher information model, wherein the material decomposition accuracy includes the Fisher information value; and / or, When the material decomposition accuracy description model includes the decomposition matrix condition number model, the energy bin receiving energy range corresponding to each energy threshold in each energy threshold combination is obtained respectively, the attenuation coefficient curve of each material to be decomposed within the energy bin receiving energy range of each energy threshold combination is determined, and the condition number corresponding to each energy threshold combination is determined according to the attenuation coefficient curve through the decomposition matrix condition number model, wherein the material decomposition accuracy includes the condition number; and / or, When the material decomposition accuracy description model includes the virtual multi-material decomposition model, the preset virtual model is scanned according to the preset spectrum by the virtual multi-material decomposition model to obtain a simulated output spectrum, and the energy bin count value corresponding to each of the energy threshold combinations is determined based on the simulated output spectrum, and the error between the energy bin count value corresponding to each of the energy threshold combinations and the theoretical count value of the preset virtual model is determined respectively, wherein the material decomposition accuracy includes the error.

5. The method according to claim 4, characterized in that In the case where the material decomposition accuracy description model includes one, screening a target energy threshold combination from the plurality of energy threshold combinations based on the material decomposition accuracy specifically includes: If the material decomposition accuracy description model is the Fisher information model, then obtaining the energy threshold combination corresponding to the maximum Fisher information value among the multiple energy threshold combinations as the target energy threshold combination; If the material decomposition accuracy description model is the decomposition matrix condition number model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum condition number is obtained as the target energy threshold combination; If the material decomposition accuracy description model is the virtual multi-material decomposition model, then among the multiple energy threshold combinations, the energy threshold combination corresponding to the minimum error is obtained as the target energy threshold combination.

6. The method according to claim 4, characterized in that In the case where the material decomposition accuracy description models include multiple ones, determining the material decomposition accuracy corresponding to each energy threshold combination by using the material decomposition accuracy description model specifically includes: Determining the material decomposition accuracy of each energy threshold combination corresponding to each material decomposition accuracy description model according to each material decomposition accuracy description model; Accordingly, the step of screening a target energy threshold combination from the plurality of energy threshold combinations based on the substance decomposition accuracy specifically includes: According to the material decomposition accuracy, respectively screening candidate energy threshold combinations corresponding to each material decomposition accuracy description model from the plurality of energy threshold combinations; Based on the material decomposition accuracy of each energy threshold combination, an evaluation value of each candidate energy threshold combination corresponding to the material decomposition accuracy description model is calculated, and the target energy threshold combination is determined from the candidate energy threshold combinations through the evaluation value.

7. The method according to any one of claims 1 to 6, characterized in that After screening a target energy threshold combination from the plurality of energy threshold combinations based on the substance decomposition accuracy, the method further includes: The energy threshold of each energy bin corresponding to the photon counter is configured according to the target energy threshold combination.

8. A device for obtaining an energy threshold of a photon counter, characterized in that: include: a threshold determination module, configured to obtain a number of energy bins expected to be used in the photon counter, and determine a plurality of energy threshold combinations based on the number of energy bins and preset threshold constraints, wherein the number of energy thresholds in each energy threshold combination is the same as the number of energy bins, and the preset threshold constraints include at least one of a first constraint, a second constraint, a third constraint, and a fourth constraint, wherein the first constraint is configured to constrain each energy threshold in each energy threshold combination to be less than or equal to the tube voltage of the photon counter, the second constraint is configured to constrain the minimum energy threshold in each energy threshold combination to be greater than or equal to the product of the tube voltage and a preset coefficient, the third constraint is configured to constrain any energy threshold in each energy threshold combination to match a k-edge energy value of any contrast agent element corresponding to a target scan object, and the fourth constraint is configured to constrain the difference between any two energy thresholds in each energy threshold combination to be greater than a preset difference; An accuracy description module, configured to determine the material decomposition accuracy corresponding to each energy threshold combination by using a material decomposition accuracy description model; A threshold screening module is used to screen a target energy threshold combination from the plurality of energy threshold combinations based on the material decomposition accuracy.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for obtaining the energy threshold of the photon counter according to any one of claims 1 to 7 is implemented.

10. A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, wherein: When the processor executes the computer program, the method for obtaining the energy threshold of the photon counter according to any one of claims 1 to 7 is implemented.

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