Neutron source correction method and apparatus for a radiotherapy planning system

Abstract

The application relates to the technical field of medical data processing, and discloses a neutron source correction method and equipment of a radiotherapy planning system, which comprises the following steps: obtaining a first value of a target physical quantity based on physical experiment measurement, and obtaining a second value of the target physical quantity corresponding to the radiotherapy planning system; the physical experiment is a physical experiment for quality assurance; if it is determined that a deviation does not meet preset requirements based on the first value of the target physical quantity and the corresponding second value, a regularization optimization model is used to obtain a target neutron input energy-angle spectrum by inversion, so that the deviation meets the preset requirements; and the neutron input energy-angle spectrum in the radiotherapy planning system is corrected based on the target neutron input energy-angle spectrum. The application can correct the neutron input energy-angle spectrum in the radiotherapy planning system, ensure the consistency of simulation results and experimental results, and thus meet the quality assurance requirements of boron neutron capture therapy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical data processing, in particular to a neutron source correction method and device of a radiotherapy planning system. BACKGROUND

[0002] A radiotherapy treatment system is a medical means for delivering a prescribed dose of radiation (X-ray, gamma ray, electron, proton and / or ion) to a diseased anatomical location by an external radiation beam to achieve the purpose of treating the diseased anatomical structure (tumor, injury, vascular malformation, neural disorder, etc.). In the process of traditional radiotherapy, in order to ensure that a prescribed dose of radiation is delivered to a diseased anatomical location, quality assurance tools and protocols are needed to verify that the prescribed radiation dose is indeed delivered to the target location to avoid inaccurate dose delivery caused by various errors in the treatment process, thereby leading to treatment failure. The radiation particles delivered by a boron neutron capture therapy (BNCT) radiotherapy system are electrically neutral neutrons, which are difficult to accurately measure. Generally, neutrons need to be converted into charged particles through some special nuclear reactions for monitoring, and the accuracy of the conversion process depends on the accuracy of the nuclear cross-section data, which has unpredictable errors in some neutron energy regions. In order to eliminate the influence of these errors on the treatment effect, a reasonable quality assurance system of boron neutron capture therapy needs to be designed to improve the accuracy of the treatment plan and the therapeutic effect of the actual treatment.

[0003] In the process of designing a treatment plan for boron neutron capture therapy, errors related to neutrons are derived from input errors of neutron energy-angle spectrum and Monte Carlo transport errors (derived from uncertainty of CT image conversion into material and experimental measurement uncertainty of neutron cross-section) in the process of Monte Carlo dose calculation.

[0004] For the input error of neutron energy-angle spectrum, the quality assurance (QA) scheme of boron neutron capture therapy (BNCT) provided by the related technology can only verify the input of the existing dose calculation neutron energy-angle spectrum, but cannot correct the input of the neutron energy-angle spectrum. SUMMARY

[0005] Therefore, the present application provides a neutron source correction method and device of a radiotherapy planning system to solve the problem that the quality assurance (QA) scheme of boron neutron capture therapy (BNCT) cannot correct the input of the neutron energy-angle spectrum.

[0006] In a first aspect, the present application provides a neutron source correction method of a radiotherapy planning system, which comprises:

[0007] obtaining a first value of a target physical quantity measured by a physical experiment, and obtaining a second value of the target physical quantity corresponding to a radiotherapy planning system; the physical experiment is a physical experiment for quality assurance, and the target physical quantity includes at least one of neutron flux, neutron dose and photon dose;

[0008] If it is determined that the deviation does not meet a preset requirement based on the first value and the corresponding second value of the target physical quantity, a regularization optimization model is used to obtain a target neutron input energy-angle spectrum, so that the deviation meets the preset requirement;

[0009] Based on the target neutron input energy-angle spectrum, the neutron input energy-angle spectrum in the radiotherapy planning system is corrected.

[0010] In an optional implementation, the regularization optimization model includes a deviation between the first value and the corresponding second value, and a regularization term based on a neutron input energy-angle spectrum;

[0011] The second value is calculated based on a neutron input energy-angle spectrum and a target transport kernel function, and the target transport kernel function is a transport kernel function corresponding to the radiotherapy planning system.

[0012] In an optional implementation, the regularization term based on the neutron input energy-angle spectrum is a product of a regularization parameter and an objective function;

[0013] The objective function is one of the following:

[0014] A square of a modulus of the neutron input energy-angle spectrum;

[0015] A square of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum;

[0016] An absolute error sum of the neutron input energy-angle spectrum.

[0017] In an optional implementation, when the objective function is a square of a modulus of the neutron input energy-angle spectrum, the corresponding regularization optimization model is:

[0018] ;

[0019] wherein, is a vector of the target physical quantity measured by the physical experiment, is a neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter.

[0020] In an alternative embodiment, the objective function is the square of the norm of the standard deviation matrix of the objective transport kernel function, plus the square of the product of a smoothing penalty operator and the neutron input energy-angle spectrum, and the corresponding regularization optimization model is:

[0021] ;

[0022] wherein, is a vector of the objective physical quantity measured by the physical experiment, is the standard deviation matrix of the objective transport kernel function, is the smoothing penalty operator, is the neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter.

[0023] In an alternative embodiment, the objective function is the sum of absolute errors of the neutron input energy-angle spectrum, and the corresponding regularization optimization model is:

[0024] ;

[0025] wherein, is a vector of the objective physical quantity measured by the physical experiment, is the neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter, denotes the energy , the angle corresponding neutron input energy-angle spectrum, denotes the energy , the angle corresponding neutron input energy-angle spectrum.

[0026] In an alternative embodiment, the regularization optimization model is solved by using a gradient descent method, a Newton method or a constrained optimization method.

[0027] In an alternative embodiment, the regularization parameter of the regularization term satisfies the following condition:

[0028] The deviation between the first value and the corresponding second value of the objective physical quantity is determined to reach a preset deviation value or be within a preset deviation range.

[0029] In an alternative embodiment, the regularization parameter of the regularization term is determined by using a grid search method, an L-curve method or a generalized cross-validation method.

[0030] In an optional implementation, the target transport kernel is obtained based on physical experimental result data of different boron concentrations and Monte Carlo simulation, wherein the physical experimental result data of different boron concentrations are obtained by performing physical experiments on water models with different boron concentrations.

[0031] In an optional implementation, the physical experiments are performed based on L groups of energy-angle pairs, L=M*N, wherein the input neutron energy corresponding to the physical experiments is divided into M groups on a logarithmic scale, and the angle corresponding to the physical experiments is divided into N groups.

[0032] In an optional implementation, in the case where the target physical quantity includes neutron flux, the sensor for collecting the neutron flux during the physical experiments includes a gold wire detector and / or a diamond detector.

[0033] In a second aspect, the present application provides a neutron source correction device of a radiotherapy planning system, the device comprising:

[0034] a numerical value acquisition module, configured to acquire a first numerical value of a target physical quantity measured based on a physical experiment, and acquire a second numerical value of the target physical quantity corresponding to the radiotherapy planning system; the physical experiment is a physical experiment for quality assurance, and the target physical quantity includes at least one of neutron flux, neutron dose and photon dose;

[0035] an inversion module, configured to, if a deviation does not satisfy a preset requirement based on the first numerical value of the target physical quantity and the corresponding second numerical value, obtain a target input neutron energy-angle spectrum by inversion using a regularization optimization model, so that the deviation satisfies the preset requirement;

[0036] a correction module, configured to correct an input neutron energy-angle spectrum in the radiotherapy planning system based on the target input neutron energy-angle spectrum.

[0037] In a third aspect, the present application provides a computer device, comprising a memory and a processor, which are communicatively connected to each other, and the memory stores computer instructions, and the processor executes the computer instructions to perform the neutron source correction method of the radiotherapy planning system according to the first aspect or any one of the corresponding implementation manners thereof.

[0038] In a fourth aspect, the present application provides a computer readable storage medium, which stores computer instructions for causing a computer to perform the neutron source correction method of the radiotherapy planning system according to the first aspect or any one of the corresponding implementation manners thereof.

[0039] In a fifth aspect, the present application provides a computer program product comprising computer instructions for causing a computer to execute the neutron source correction method of the radiotherapy planning system according to the first aspect or any of the corresponding embodiments thereof.

[0040] The method and device for correcting a neutron source of a radiotherapy planning system provided by the present embodiment provide a method for obtaining a neutron input energy-angle spectrum, correct the neutron input energy-angle spectrum in a radiotherapy planning system based on experimental data, ensure the consistency between simulation results and experimental results, and thus meet the quality assurance requirements of boron neutron capture therapy. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the specific embodiments or the related art, the drawings needed in the specific embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 is a flowchart of the method for correcting a neutron source of a radiotherapy planning system according to an embodiment of the present application;

[0043] Fig. 2(a) is one of the schematic diagrams of the physical experiment in the quality assurance scheme of boron neutron capture therapy;

[0044] Fig. 2(b) is another schematic diagram of the physical experiment in the quality assurance scheme of boron neutron capture therapy;

[0045] Figure 3 is a schematic diagram of the total neutron energy spectrum before and after inputting MC simulation according to an embodiment of the present application;

[0046] Figure 4 is a schematic diagram of the thermal neutron flux change with depth along the beam direction in the water tank before and after correction according to an embodiment of the present application;

[0047] Figure 5 is a structural block diagram of the device for correcting a neutron source of a radiotherapy planning system according to an embodiment of the present application;

[0048] Figure 6 is a schematic diagram of the hardware structure of the computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0050] According to the embodiments of the present application, a neutron source correction method of a radiotherapy planning system is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of executable computer instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0051] In the present embodiment, a neutron source correction method of a radiotherapy planning system is provided, which can be used in various computer devices, Figure 1 is a flowchart of the neutron source correction method of the radiotherapy planning system according to the embodiments of the present application, as Figure 1 shown, the flow includes the following steps:

[0052] In step S101, a first value of a target physical quantity based on physical experiment measurement is obtained, and a second value of the target physical quantity corresponding to the radiotherapy planning system is obtained. The physical experiment is a physical experiment for quality assurance, and the target physical quantity includes at least one of neutron flux, neutron dose and photon dose. Each specific physical quantity has a corresponding value (first value or second value). For example, when the target physical quantity includes neutron flux, neutron dose and photon dose, the neutron flux, neutron dose and photon dose each have a corresponding first value and second value. In addition, one specific target physical quantity can also have multiple first values and multiple second values. For example, the specific target physical quantity of neutron flux can include multiple first values and second values at different positions.

[0053] Specifically, Monte Carlo simulation can be used in the radiotherapy planning system for dose calculation, and analytical methods such as pencil beam and cone beam can also be used for dose calculation. The second value can be calculated based on neutron input energy-angle spectrum and target transport kernel function. The target transport kernel function is the transport kernel function corresponding to the radiotherapy planning system.

[0054] In the second numerical value of the target physical quantity based on the target transport kernel function, the target transport kernel function needs to be calculated in advance. Specifically, it can be solved by discrete ordinate method or Monte Carlo simulation. The accuracy of Monte Carlo simulation is higher. Specifically, the geometric model of the phantom (which can be a water phantom, but is not limited to a water phantom) and the mass fraction of different elements in the water phantom material obtained by testing as the water phantom material composition information are input into the Monte Carlo engine of the Treatment Planning System (TPS) software, and then the Monte Carlo simulation is performed to obtain the transport kernel function .

[0055] The above physical experiment can be a standard physical experiment for quality assurance (QA) of radiotherapy. As shown in FIGS. 2(a) and 2(b), a certain size of cubic water phantom is usually used to measure the neutron flux, neutron dose, and photon dose (usually measured by activated gold wire / foil, dosimeter, and ionization chamber) under a specific monitor unit (MU).

[0056] In step S102, if it is determined that the deviation does not meet the preset requirement based on the first numerical value of the target physical quantity and the corresponding second numerical value, the target neutron input energy-angle spectrum is obtained by inversion using a regularization optimization model, so that the deviation meets the preset requirement. In the inversion process, each iteration needs to obtain the corresponding second numerical value of the target physical quantity based on the updated neutron input energy-angle spectrum, and calculate the deviation based on the new second numerical value. As described above, the new second numerical value also needs to be obtained by Monte Carlo simulation based on the new neutron input energy-angle spectrum.

[0057] Specifically, the deviation here can be a square error or an absolute value deviation error. The preset requirement can be that the deviation is less than a preset threshold (which can be determined according to actual needs). For the regularization optimization model, see the following.

[0058] In step S103, the neutron input energy-angle spectrum in the radiotherapy planning system is corrected based on the target neutron input energy-angle spectrum. Specifically, the target neutron input energy-angle spectrum can be directly used as the neutron input energy-angle spectrum in the radiotherapy planning system.

[0059] The neutron input energy-angle spectrum (i.e., the neutron source term energy-angle spectrum) is: , is the cosine value of the angle between the neutron momentum direction and the beam direction, wherein The kinetic energy of the outgoing neutron is represented, considering that the spatial distribution of the neutron at the outlet of the boron neutron capture therapy beam is approximately uniform, the neutron flux at a point in space can be modeled as:

[0060]

[0061] where, is the transport kernel function, which describes the influence of a neutron with energy , outgoing angle cosine on the neutron flux at position, is the position vector relative to the center of the water phantom.

[0062] In the embodiments of the present application, in order to alleviate the time pressure of experimental measurement, the required neutron input energy and angle of physical experiments can be grouped, the neutron input energy is divided into M groups on a logarithmic scale, and the angle is divided into N groups, so that the physical experiment is based on L=M×N group energy-angle pairs to perform experiments and measurements. For example, the input energy to be calibrated online is set to 10 -6 MeV to 1.1 MeV in 8 groups on a logarithmic scale, and the input angle to be calibrated online is set to 5 groups uniformly distributed from -1 to 1 in the angle cosine value, that is, the source term is discretized into N=8×5=40 groups (the number of experimental groups can be adjusted according to the accuracy requirement) energy-angle channels, and the integral relationship is converted into a linear algebra form:

[0063]

[0064] where, represents the flux vector of M measurement points (recommended to be greater than 15) under multiple experimental conditions (that is, multiple different boron concentrations), represents the measurement error of the M measurement points.

[0065] The purpose of the quality assurance (QA) process of radiotherapy is to ensure that the actual delivered radiation dose is consistent with the radiation therapy plan calculated radiation dose. The neutron source correction method of the radiotherapy planning system provided in the embodiments provides a method for obtaining a neutron input energy-angle spectrum, corrects the neutron input energy-angle spectrum in the radiotherapy planning system based on experimental data, ensures the consistency of simulation results and experimental results, and meets the quality assurance requirements of boron neutron capture therapy.

[0066] In addition, in order to enhance the solvability of the inverse problem and alleviate its high ill-conditioned nature, the present method controls the boron content in the water phantom, changes the thermalization and absorption process of the neutron, and thus effectively modulates the kernel function . The specific experimental settings are as follows:

[0067] A plurality of groups of boric acid concentrations are set: 0 ppm (pure water), 10 ppm, 20 ppm, 40 ppm, and 60 ppm; for each group of boric acid concentrations, the neutron flux distribution of the corresponding space at the corresponding boric acid concentration is measured at M positions: Different boron concentrations correspond to different transport kernel functions, and the transport kernel functions are expanded according to the concentrations, that is: .

[0068] In the embodiment of the present application, the energy-angle spectrum of the source term is inversed in a regularization optimization framework by combining the physical quantity measurement data under different boron concentration experimental conditions in the water tank (i.e., the water phantom) and the transport kernel matrix obtained by high-precision MC simulation, and online energy spectrum adaptive correction is realized. This method not only improves the reliability of boron neutron capture therapy dose simulation, but also has realizability and clinical practicability, and provides a new technical path for boron neutron capture therapy quality control.

[0069] Specifically, the inversed energy-angle spectrum of the source term can be the neutron energy-angle spectrum at the outlet of the boron neutron capture therapy beam (including but not limited to the outlet of the collimator and the outlet of the beam shaping system), online correction of the input source term is realized, and the accuracy and consistency of dose calculation are improved. This method can be directly embedded into the existing quality control process, and the consistency with the clinical verification result is significantly improved.

[0070] The regularization optimization model is exemplified below.

[0071] In some optional specific embodiments, the regularization optimization model includes a deviation between the first value and the corresponding second value, and a regularization term based on the neutron input energy-angle spectrum.

[0072] Specifically, as described above, the deviation between the first value and the corresponding second value can be a square error, that is , wherein, is a vector of the target physical quantity (including but not limited to neutron flux) obtained by the physical experiment measurement, is a neutron input energy-angle spectrum, is the transport kernel function. In the embodiment of the present application, considering that there are statistical errors in the experimental measurement and MC calculation, a regularization optimization model is used to solve the inversed neutron source.

[0073] In some optional specific embodiments, the regularization term based on the neutron input energy-angle spectrum is a product of a regularization parameter and the objective function;

[0074] The objective function is one of the following:

[0075] a square of a norm of the neutron input energy-angle spectrum;

[0076] a square of a norm of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum;

[0077] an absolute error sum of the neutron input energy-angle spectrum.

[0078] Specifically, the regularization parameter is used to balance the fitting error and the prior smoothness.

[0079] When the objective function is a square of a norm of the neutron input energy-angle spectrum, the expression of the objective function is: , and correspondingly, the regularized optimization model is: ;

[0080] When the objective function is a square of a norm of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum, the smoothing penalty operator can be, for example, a first-order difference operator, the expression of the objective function is: , and correspondingly, the regularized optimization model is: , wherein denotes a standard deviation matrix of the target transport kernel function in MC calculation, is a first-order difference operator, used to suppress the sharp oscillation of the energy spectrum in the energy or angle dimension;

[0081] When the objective function is an absolute error sum of the neutron input energy-angle spectrum, the expression of the objective function is: , and correspondingly, the regularized optimization model is:

[0082] , wherein denotes an energy , an angle corresponding neutron input energy-angle spectrum, denotes an energy , an angle corresponding neutron input energy-angle spectrum, an energy and an energy have a value range of 10 -6 MeV to 1.1 MeV, an angle and an angle have a value range of 0-90 degrees. As described previously, the energy and the energy can have 8 values, and the angle and the angle can have 5 values.

[0083] In addition, the constructed regularization optimization model further comprises a constraint condition: The non-negative constraint of the neutron input energy-angle spectrum is used to ensure the physical reasonableness of the spectrum.

[0084] In the embodiment of the present application, when the optimization problem (i.e., the regularization optimization model) is constructed to solve the physical quantity to be inverted (i.e., the neutron input energy-angle spectrum), a plurality of different problem forms as described above can be constructed.

[0085] In some optional specific embodiments, the regularization optimization model is solved by using a gradient descent method, a Newton method or a constraint optimization method (such as a Limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm with Box constraints, L-BFGS-B).

[0086] In some optional specific embodiments, regarding the selection of the regularization parameter, the total experimental error can be defined as:

[0087]

[0088] wherein, is the flux standard error of the i th experimental position.

[0089] According to the Morozov ill-posed problem compatibility principle, the ideal regularization parameter should satisfy: Therefore, the regularization parameter of the regularization term satisfies the following condition:

[0090] Based on the deviation between the first value of the target physical quantity and the corresponding second value, the deviation reaches a preset deviation value or is within a preset deviation range, and the preset deviation value and the preset deviation range are determined according to an empirical value or according to the accuracy requirement.

[0091] In the embodiment of the present application, the regularization parameter of the regularization term can be determined by using a grid search method, an L-curve method or a Generalized Cross-Validation (GCV) method.

[0092] ​Among them, the grid search method is a general method of finding the best parameters through exhaustive search and direct verification. The L-curve method is a visual and heuristic-based method derived from solving inverse problems, with good interpretability. The generalized cross-validation method is an automated method based on statistical theory, which is an efficient approximation of leave-one-out cross-validation. The core idea is that a good model should have the ability to predict unknown data, that is, even if any data point is removed, the model can still predict it well.

[0093] In some optional embodiments, when the target physical quantity includes neutron flux, the sensor for collecting the neutron flux during the physical experiment includes a gold wire detector and / or a diamond detector.

[0094] Regarding the experimental measurement system, when the target physical quantity includes neutron flux, in order to achieve accurate measurement of the neutron flux distribution, especially effective collection of the spatial flux response under boron water solution modulation, the embodiments of the present application design a neutron flux measurement system based on various detector combinations, including but not limited to: gold wire detector and diamond detector.

[0095] Specifically, the gold wire (197Au) detector is based on the principle of neutron activation, and the following reaction occurs under thermal neutron irradiation: , is The emitter can indirectly obtain the thermal neutron flux through radioactivity measurement. The gold wire (197Au) detector is mainly used to measure the thermal neutron flux distribution and can be embedded and arranged at multiple depths along the axial and radial directions of the water phantom (i.e. water tank). After irradiation, the activity spectrum can be measured by a high-purity germanium detector (HPGe), which has good linearity and clear energy response function, and is suitable for calibrating the MC simulation flux normalization factor.

[0096] The diamond detector uses natural or chemical vapor deposition (CVD) synthetic diamond to generate charge collection signals caused by elastic scattering and nuclear reaction processes of fast neutrons and thermal neutrons, and can realize online measurement of a wide range of neutron energies. The diamond detector is suitable for measuring the spatial distribution of fast neutrons and surface area neutrons, has extremely high radiation resistance, excellent time response, and low cost, and can be embedded in the water tank transparent window or sliding rail structure through a waterproof interface, allowing mobile measurement. After coupling with a high-speed charge amplifier, the flux signal is collected in real time by a data acquisition system (DAQ).

[0097] In summary, during physical experiments, the embodiments of the present invention can use various detectors to measure different physical quantities, such as thermal neutron flux, ultrathermal neutron flux, fast neutron flux, neutron dose rate, etc.

[0098] Figure 3 The total neutron energy spectrum input to the MC simulation before and after correction is shown. Figure 4 The curves showing the thermal neutron flux along the beam direction in the water tank before and after correction are presented. It can be seen that the calculated results after correction are significantly more consistent with experimental results; therefore, the calibrated input is clearly more in line with clinical needs.

[0099] In summary, this invention proposes a technical chain in the process of boron neutron capture therapy dose verification, which combines quality assurance (QA) experimental measurements and Monte Carlo simulations with an energy spectrum deconvolution algorithm (an algorithm used to optimize the objective function and extract source data) to correct the dose calculation input, so as to obtain more reliable physical dose distribution results in clinical practice.

[0100] This embodiment also provides a neutron source correction device for a radiotherapy planning system, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0101] This embodiment provides a neutron source correction device for a radiotherapy planning system, such as... Figure 5 As shown, it includes:

[0102] The numerical acquisition module is used to acquire a first value of the target physical quantity obtained based on physical experiment measurements, and to acquire a second value of the target physical quantity corresponding to the radiotherapy planning system; the physical experiment is a physical experiment for quality assurance, and the target physical quantity includes at least one of neutron flux, neutron dose, and photon dose;

[0103] The inversion module is used to obtain the target neutron input energy-angle spectrum by using a regularization optimization model if the deviation between the first value and the corresponding second value of the target physical quantity does not meet the preset requirements, so that the deviation meets the preset requirements.

[0104] The correction module is used to correct the neutron input energy-angle spectrum in the radiotherapy planning system based on the target neutron input energy-angle spectrum.

[0105] In some alternative embodiments, the regularization optimization model comprises a deviation between the first value and a corresponding second value, and a regularization term based on a neutron input energy-angle spectrum;

[0106] The second value is calculated based on a neutron input energy-angle spectrum and a target transport kernel function, the target transport kernel function being a transport kernel function corresponding to the radiotherapy planning system.

[0107] In some alternative embodiments, the regularization term based on the neutron input energy-angle spectrum is a product of a regularization parameter and an objective function;

[0108] The objective function is one of:

[0109] a square of a modulus of the neutron input energy-angle spectrum;

[0110] a square of a modulus of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum;

[0111] an absolute error sum of the neutron input energy-angle spectrum.

[0112] In some alternative embodiments, when the objective function is a square of a modulus of the neutron input energy-angle spectrum, the corresponding regularization optimization model is:

[0113] ;

[0114] wherein, is a vector of the target physical quantity measured by the physical experiment, is a neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter.

[0115] In some alternative embodiments, when the objective function is a square of a modulus of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum, the corresponding regularization optimization model is:

[0116] ;

[0117] wherein, is a vector of the target physical quantity measured by the physical experiment, is a standard deviation matrix of the target transport kernel function, is the smoothing penalty operator, is a neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter.

[0118] In some optional embodiments, the objective function is a sum of absolute errors of the neutron input energy-angle spectrum, and the corresponding regularization optimization model is:

[0119] ;

[0120] wherein, is a vector of the target physical quantity measured by the physical experiment, is a neutron input energy-angle spectrum, is the transport kernel function, is a regularization parameter, denotes energy , angle , and the corresponding neutron input energy-angle spectrum, denotes energy , angle , and the corresponding neutron input energy-angle spectrum.

[0121] In some optional embodiments, the regularization optimization model is solved by using a gradient descent method, a Newton method, or a constrained optimization method.

[0122] In some optional embodiments, the regularization parameter of the regularization term satisfies the following condition:

[0123] Based on the deviation between the first value of the target physical quantity and the corresponding second value, the deviation reaches a preset deviation threshold, or is within a preset deviation range.

[0124] In some optional embodiments, the regularization parameter of the regularization term is determined by using a grid search method, an L-curve method, or a generalized cross-validation method.

[0125] In some optional embodiments, the target transport kernel function is obtained based on physical experimental result data of different boron concentrations and Monte Carlo simulation, wherein the physical experimental result data of different boron concentrations refer to result data obtained by performing physical experiments on water models with different boron concentrations.

[0126] In some optional embodiments, the physical experiment is performed based on L groups of energy-angle pairs, L = M x N, the corresponding neutron input energy of the physical experiment is divided into M groups according to a logarithmic scale, and the corresponding angle of the physical experiment is divided into N groups.

[0127] In some optional embodiments, in the case where the target physical quantity includes neutron flux, the sensor for collecting the neutron flux during the physical experiment includes a gold wire detector and / or a diamond detector.

[0128] Further functional descriptions of the above modules are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0129] In this embodiment, the neutron source correction device of the radiotherapy planning system is presented in the form of a functional unit. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0130] This invention also provides a computer device having the above-described features. Figure 5 The neutron source correction device of the radiotherapy planning system shown.

[0131] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 6 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 6 Take a processor 10 as an example.

[0132] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0133] The memory 20 stores instructions executable by at least one processor 10 to cause the at least one processor 10 to perform the method shown in the above embodiments.

[0134] The memory 20 can include a program storage area and a data storage area. The program storage area can store an operating system, application programs required for at least one function, etc. The data storage area can store data created by the computer device, etc. In addition, the memory 20 can include a high-speed random access memory, and can also include a non-transitory memory such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid state memory device. In some alternative embodiments, the memory 20 can optionally include memory that is remotely located with respect to the processor 10, and which can be connected to the computer device through a network. Examples of such networks include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communications network, and combinations thereof.

[0135] The memory 20 can include a volatile memory, such as a random access memory, and / or can include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid state memory device. The memory 20 can also include an array of multi-state flash memory cells, which can be used to store data and / or instructions in multiple states.

[0136] The computer device also includes a communications interface 30 for communicating with other devices or communication networks.

[0137] The embodiments of the present application also provide a computer readable storage medium, and the method according to the embodiments of the present application can be implemented in hardware, firmware, or recorded in a storage medium, or implemented as computer code to be originally stored in a remote storage medium or a non-transitory machine readable storage medium downloaded through a network and stored in a local storage medium, so that the method described herein can be processed by such software on a storage medium using a general purpose computer, a special purpose processor, or programmable or special purpose hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid state disk, etc. Further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that the computer, processor, microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the method shown in the above embodiments.

[0138] Part of the present application can be applied as a computer program product, for example, computer program instructions, when executed by a computer, through the operation of the computer, can invoke or provide the method and / or technical solutions according to the present application. Those skilled in the art should understand that the form of computer program instructions in computer readable medium includes but is not limited to source files, executable files, installation package files and the like, and accordingly, the way of computer program instructions executed by computer includes but is not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer readable medium can be any available computer readable storage medium or communication medium accessible to the computer.

[0139] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A neutron source correction method of a radiotherapy planning system, characterized by, The method comprises: obtaining a first value of a target physical quantity measured based on a physical experiment, and obtaining a second value of the target physical quantity corresponding to a radiotherapy planning system; the physical experiment is a physical experiment for quality assurance, and the target physical quantity comprises at least one of neutron flux, neutron dose and photon dose; if it is determined that a deviation between the first value and the corresponding second value of the target physical quantity does not satisfy a preset requirement, a target neutron input energy-angle spectrum is obtained by inversion using a regularization optimization model, so that the deviation satisfies the preset requirement; based on the target neutron input energy-angle spectrum, a neutron input energy-angle spectrum in the radiotherapy planning system is corrected.

2. The method of claim 1, wherein, The regularization optimization model comprises a deviation between the first value and the corresponding second value, and a regularization term based on the neutron input energy-angle spectrum; The second value is calculated based on the neutron input energy-angle spectrum and a target transport kernel function, and the target transport kernel function is a transport kernel function corresponding to the radiotherapy planning system.

3. The method of claim 2, wherein, The regularization term based on the neutron input energy-angle spectrum is a product of a regularization parameter and a target function; The target function is one of: a square of a norm of the neutron input energy-angle spectrum; a square of a norm of a standard deviation matrix of the target transport kernel function, plus a square of a product of a smoothing penalty operator and the neutron input energy-angle spectrum; an absolute error sum of the neutron input energy-angle spectrum.

4. The method of claim 3, wherein, When the target function is the square of the norm of the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ； wherein, a vector of the target physical quantity measured by the physical experiment, a neutron input energy-angle spectrum, the transport kernel function, a regularization parameter.

5. The method of claim 3, wherein, When the target function is the square of the norm of the standard deviation matrix of the target transport kernel function, plus the square of the product of the smoothing penalty operator and the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ； wherein, a vector of the target physical quantities measured by the physical experiment, a standard deviation matrix of the target transport kernel, a smoothing penalty operator, a neutron input energy-angle spectrum, the transport kernel, a regularization parameter.

6. The method of claim 3, wherein, When the target function is the absolute error sum of the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ； wherein, a vector of the target physical quantities measured by the physical experiment, a neutron input energy-angle spectrum, the transport kernel function, a regularization parameter, denotes the energy , the angle the corresponding neutron input energy-angle spectrum, denotes the energy , the angle the corresponding neutron input energy-angle spectrum.

7. The method of claim 2, wherein, The regularization parameter of the regularization term satisfies the following condition: The deviation determined based on the first value and the corresponding second value of the target physical quantity reaches a preset deviation value or is within a preset deviation range.

8. The method of claim 2, wherein, The target transport kernel function is obtained based on physical experiment result data of different boron concentrations combined with Monte Carlo simulation, and the physical experiment result data of different boron concentrations are result data obtained by performing a physical experiment on a water phantom with different boron concentrations.

9. The method of claim 1, wherein, The physical experiment is performed based on L energy-angle pairs, L=M×N, the corresponding neutron input energy of the physical experiment is divided into M groups on a logarithmic scale, and the corresponding angle of the physical experiment is divided into N groups.

10. A computer device, comprising: comprise: a memory and a processor, which are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the neutron source correction method of the radiotherapy planning system in any one of claims 1 to 9.

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