Neutron source correction method and device of radiotherapy planning system

Abstract

The invention relates to the technical field of medical data processing, and discloses a neutron source correction method and equipment for a radiotherapy planning system, and the method comprises the steps: obtaining a first value of a target physical quantity obtained 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 used for quality guarantee; if it is determined that the deviation does not meet the preset requirement based on the first numerical value and the corresponding second numerical value of the target physical quantity, the target neutron input energy-angle spectrum is obtained through inversion by means of a regularization optimization model, so that the deviation meets the preset requirement; and correcting the neutron input energy-angle spectrum in the radiotherapy planning system based on the target neutron input energy-angle spectrum. According to the invention, the neutron input energy-angle spectrum in a radiotherapy planning system can be corrected, and the consistency of a simulation result and an experimental result is ensured, so that the requirement of boron neutron capture therapy on quality assurance is met.

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, and there are 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, the method comprising: 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; 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; Based on the target neutron input energy-angle spectrum, the neutron input energy-angle spectrum in the radiotherapy planning system is corrected.

[0007] 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 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.

[0008] 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; The objective function is one of the following: 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.

[0009] In an optional implementation, when the objective function is a square of a norm of the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ; 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.

[0010] In an optional implementation, 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 corresponding regularization optimization model is: ; 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.

[0011] In an optional implementation, the objective function is a sum of absolute errors of the neutron input energy-angle spectrum, and the corresponding regularization optimization model is: ; 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 corresponding to the neutron input energy-angle spectrum, denotes energy , angle corresponding to the neutron input energy-angle spectrum.

[0012] In an optional implementation, the regularization optimization model is solved by using a gradient descent method, a Newton method or a constraint optimization method.

[0013] In an optional implementation, the regularization parameter of the regularization term satisfies the following condition: a deviation between the first value and the corresponding second value of the target physical quantity is less than or equal to a preset deviation value, or is within a preset deviation range.

[0014] In an optional implementation, 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.

[0015] In an optional implementation, 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 are result data obtained by performing physical experiments on water models with different boron concentrations.

[0016] In an optional implementation, the physical experiment is performed based on L groups of energy-angle pairs, L=MxN, the input neutron energy corresponding to the physical experiment is divided into M groups on a logarithmic scale, and the angle corresponding to the physical experiment is divided into N groups.

[0017] In an optional implementation, in a 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.

[0018] In a second aspect, the present application provides a neutron source correction device of a radiotherapy planning system, the device comprising: 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; 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, acquire a target input neutron energy-angle spectrum by inversion using a regularization optimization model, so that the deviation satisfies the preset requirement; 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.

[0019] In a third aspect, the present application provides a computer device, comprising a memory and a processor, which are communicatively connected with each other, 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.

[0020] In a fourth aspect, the present application provides a computer readable storage medium, which stores computer instructions, and the computer instructions are used to make a computer execute the neutron source correction method of the radiotherapy planning system according to the first aspect or any one of the corresponding implementation manners thereof.

[0021] In a fifth aspect, the present application provides a computer program product, which comprises computer instructions, and the computer instructions are used to make a computer execute the neutron source correction method of the radiotherapy planning system according to the first aspect or any one of the corresponding implementation manners thereof.

[0022] The embodiment provides a neutron source correction method and device of a radiotherapy planning system, provides a neutron input energy-angle spectrum acquisition method, corrects a neutron input energy-angle spectrum in a radiotherapy planning system based on experimental data, guarantees consistency of simulation results and experimental results, and meets a requirement of boron neutron capture therapy for quality assurance. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments or related art, the drawings needed to be used in the specific embodiments or 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.

[0024] Figure 1 Fig. 1 is a flowchart of a neutron source correction method of a radiotherapy planning system according to an embodiment of the present application; Fig. 2(a) is one of the schematic diagrams of physical experiments in the quality assurance scheme of boron neutron capture therapy; Fig. 2(b) is another schematic diagram of physical experiments in the quality assurance scheme of boron neutron capture therapy; Figure 3 Fig. 3 is a schematic diagram of total neutron energy spectrum before and after input MC simulation correction according to an embodiment of the present application; Figure 4 Fig. 4 is a schematic diagram of thermal neutron flux change with depth in the water tank along the beam direction before and after correction according to an embodiment of the present application; Figure 5 Fig. 5 is a structural block diagram of a neutron source correction device of a radiotherapy planning system according to an embodiment of the present application; Figure 6 Fig. 6 is a schematic diagram of a hardware structure of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0026] According to the embodiment 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 shown here.

[0027] 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 embodiment of the present application, as Figure 1 shown, the flow includes the following steps: Step S101, 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, 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.

[0028] 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 to calculate the dose. The second value can be calculated based on the neutron input energy-angle spectrum and the target transport kernel function, and the target transport kernel function is the transport kernel function corresponding to the radiotherapy planning system.

[0029] When the second value of the target physical quantity is calculated based on the target transport kernel function, the target transport kernel function needs to be calculated in advance. It can be solved by discrete longitudinal method or Monte Carlo simulation. Monte Carlo simulation has higher accuracy, and 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 can be input into the Monte Carlo engine of the radiotherapy planning system (TPS) software, and then the Monte Carlo simulation is performed to obtain the transport kernel function .

[0030] The above physical experiment can be a standard physical experiment for quality assurance (QA) of radiotherapy, as shown in FIG. 2(a) and FIG. 2(b), and a certain size of a cubic water phantom is usually used to measure the neutron flux, neutron dose, and photon dose (usually measured by using activated gold wire / foil, dosimeter, and ionization chamber) under a specific monitor unit (MU).

[0031] In step S102, if it is determined that the deviation does not meet the preset requirement 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, so that the deviation meets the preset requirement. In the inversion process, each iteration needs to obtain the corresponding second value of the target physical quantity based on the updated neutron input energy-angle spectrum, and calculate the deviation based on the new second value. As described above, the new second value is also obtained by Monte Carlo simulation based on the new neutron input energy-angle spectrum.

[0032] 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.

[0033] 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.

[0034] 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, where represents the kinetic energy of the outgoing neutron. Considering that the spatial distribution of neutrons at the outlet of the boron neutron capture therapy beam is approximately uniform, the neutron flux at a certain point in space can be modeled as:

[0035] where, is the transport kernel function, which is used to describe the influence of the neutron with energy and outgoing angle cosine on the neutron flux at position , and represents the position vector relative to the center of the water phantom.

[0036] In the embodiment of the present application, in order to reduce the time pressure of experimental measurement, the neutron input energy and angle required by the physical experiment 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=MxN group energy-angle pairs for experiment and measurement. For example, the input energy to be calibrated online is set to 10 -6 MeV to 1.1 MeV 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=8x5=40 groups (the number of groups of the experiment can be adjusted according to the accuracy requirement) energy-angle channels, and the integral relationship is converted into a linear algebra form:

[0037] wherein, 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.

[0038] 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 embodiment 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 requirements of boron neutron capture therapy for quality assurance.

[0039] In addition, in order to enhance the solvability of the inverse problem and alleviate its high ill-conditioned nature, the method controls the boron content in the water phantom, changes the thermalization and absorption process of neutrons, and effectively modulates the nuclear function . The specific experimental settings are as follows: A plurality 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 concentration, the neutron flux distribution of M positions in the corresponding space under the corresponding boric acid concentration is measured: . Different boron concentrations correspond to different transport nuclear functions, and the transport nuclear function is expanded according to the concentration, that is, .

[0040] The embodiment of the present application realizes online energy spectrum adaptive correction by measuring physical quantity data under different boron concentration experimental conditions in the water tank (i.e., water phantom), combining the transport kernel matrix obtained by high-precision MC simulation, and inverting the energy-angle spectrum of the source term under the regularization optimization framework. This method not only improves the reliability of boron neutron capture therapy dose simulation, but also has realizability and clinical practicability, providing a new technical path for boron neutron capture therapy quality control.

[0041] Specifically, the energy-angle spectrum of the inverted 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), realizing online correction of the input source term, thereby improving the accuracy and consistency of dose calculation. This method can be directly embedded in the existing quality control process and significantly improve the consistency with the clinical verification results.

[0042] The regularization optimization model is illustrated below.

[0043] In some optional specific embodiments, the regularization optimization model includes the deviation between the first value and the corresponding second value, and a regularization term based on the neutron input energy-angle spectrum.

[0044] Specifically, as described above, the deviation between the first value and the corresponding second value can be a square error, i.e. wherein, is a vector of the target physical quantity (including but not limited to neutron flux) obtained by 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 experimental measurement and MC calculation, a regularization optimization model is used to solve the inverted neutron source.

[0045] In some optional specific embodiments, the regularization term based on the neutron input energy-angle spectrum is the product of a regularization parameter and the objective function; The objective function is one of the following: the square of the norm of the neutron input energy-angle spectrum; the square of the norm of the standard deviation matrix of the target transport kernel function, plus the square of the product of a smoothing penalty operator and the neutron input energy-angle spectrum; the absolute error sum of the neutron input energy-angle spectrum.

[0046] Specifically, the regularization parameter is used to balance the fitting error and the prior smoothness.

[0047] When the objective function is the square of the modulus of the neutron input energy-angle spectrum, the expression for the objective function is: Accordingly, the regularization optimization model is: ; When the objective function is the square of the modulus 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 smoothing penalty operator can be, for example, a first-order difference operator, and the expression of the objective function is: Accordingly, the regularization optimization model is: ,in, , represents the standard deviation matrix of the target transport kernel function in MC calculation. It is a first-order difference operator used to suppress violent oscillations in the energy or angular dimensions of the energy spectrum; When the objective function is the sum of absolute errors of the neutron input energy-angle spectrum, the expression for the objective function is: Accordingly, the regularization optimization model is: ,in, Represents energy ,angle The corresponding neutron input energy-angle spectrum, Represents energy ,angle The corresponding neutron input energy-angle spectrum, energy and energy The value range is 10 -6 MeV to 1.1MeV, angle and angle The value ranges from 0 to 90 degrees. As mentioned earlier, energy... and energy The value can have 8 values, angle and angle It can have 5 possible values.

[0048] In addition, the constructed regularized optimization model also includes a constraint: The non-negative constraint of the neutron input energy-angle spectrum is used to ensure the rationality of spectral physics.

[0049] In this embodiment of the invention, when constructing an optimization problem (i.e., a regularized optimization model) to solve for the physical quantity to be inverted (i.e., the neutron input energy-angle spectrum), various different problem forms as described above can be constructed.

[0050] In some optional embodiments, the regularization optimization model is solved by using a gradient descent method, a Newton method or a constrained optimization method (such as a Limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm with Box constraints, L-BFGS-B).

[0051] In some optional embodiments, the total experimental error can be defined as follows with respect to the selection of the regularization parameter.

[0052] wherein, is the flux standard error of the i th experimental position.

[0053] 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: The deviation is determined based on the first value and the corresponding second value of the target physical quantity, and the deviation reaches a preset deviation value or is within a preset deviation range. The preset deviation value and the preset deviation range are determined according to an empirical value or according to the accuracy requirement.

[0054] In the embodiments 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.

[0055] The grid search method is a general method for finding the best parameter by exhaustive search and direct verification. The L-curve method is a visual and heuristic method, which is derived from solving inverse problems and has good interpretability. The Generalized Cross-Validation method is an automatic method based on statistical theory, which is a high-efficiency approximation of the 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.

[0056] In some optional embodiments, when the target physical quantity includes neutron flux, the sensor for collecting the neutron flux in the physical experiment process includes a gold wire detector and / or a diamond detector.

[0057] ​​Regarding the experimental measurement system, in the case that the target physical quantity includes neutron flux, in order to realize accurate measurement of the neutron flux distribution, especially effective acquisition of the spatial flux response under boron water solution modulation, the embodiment of the present application designs a neutron flux measurement system based on a plurality of detector combinations, including but not limited to: gold wire detectors and diamond detectors.

[0058] Specifically, the gold wire (197Au) detector is based on the principle of neutron activation, and the following reaction occurs under thermal neutron irradiation: , wherein, is The emitter can indirectly obtain the thermal neutron flux through radioactivity measurement. The gold wire (197Au) detector is mainly used for measuring 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., the 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.

[0059] The diamond detector utilizes 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 relatively 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, can be embedded in the transparent window or sliding rail structure of the water tank through a waterproof interface, allows movable measurement, and after being coupled with a high-speed charge amplifier, the flux signal is collected in real time through a data acquisition system (DAQ). The advantage of the diamond detector is that it responds quickly and is convenient for online monitoring.

[0060] In summary, in the physical experiment process, the embodiment of the present application can use a plurality of detectors to measure different physical quantities, such as thermal neutron flux, epithermal neutron flux, fast neutron flux, and neutron dose rate.

[0061] Figure 3 The total neutron energy spectrum before and after correction is shown in the input MC simulation, Figure 4 The curve of the thermal neutron flux along the beam direction in the water tank before and after correction is shown. It can be seen that after correction, the calculated result is obviously more consistent with the experimental result, and therefore the calibrated input is obviously more consistent with the clinical requirements.

[0062] In summary, the embodiment of the present application proposes a technical chain in the process of boron neutron capture therapy dose verification, which can obtain more reliable physical dose distribution results in the clinic by jointly correcting the dose calculation input through quality assurance (QA) experimental measurement and Monte Carlo simulation, and a spectrum deconvolution algorithm (an algorithm for optimizing the objective function and extracting source data).

[0063] In the embodiment, a neutron source correction device of a radiotherapy planning system is also provided, which is used to implement the above-mentioned embodiments and preferred embodiments, and details are not repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware is also possible and contemplated.

[0064] The embodiment provides a neutron source correction device of a radiotherapy planning system, as shown in the accompanying drawings, comprising: Figure 5 a numerical value acquisition module, configured to acquire a first numerical value of a target physical quantity based on physical experimental measurement, 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; an inversion module, configured to, if it is determined that a deviation does not meet a preset requirement based on the first numerical value of the target physical quantity and the corresponding second numerical value, obtain a target neutron input energy-angle spectrum by inversion using a regularization optimization model, so that the deviation meets the preset requirement; a correction module, configured to correct the neutron input energy-angle spectrum in the radiotherapy planning system based on the target neutron input energy-angle spectrum.

[0065] In some optional embodiments, the regularization optimization model includes a deviation between the first numerical value and the corresponding second numerical value, and a regularization term based on the neutron input energy-angle spectrum; The second numerical 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.

[0066] In some optional embodiments, the regularization term based on the neutron input energy-angle spectrum is a product of a regularization parameter and an objective function; The objective function is one of: a square of a modulus 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.

[0067] In some optional embodiments, when the objective function is a square of a norm of the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ; 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.

[0068] In some optional embodiments, 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 corresponding regularization optimization model is: ; 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.

[0069] In some optional embodiments, when the objective function is an absolute error sum of the neutron input energy-angle spectrum, the corresponding regularization optimization model is: ; 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 corresponding neutron input energy-angle spectrum, denotes energy , angle corresponding neutron input energy-angle spectrum.

[0070] In some optional embodiments, the regularization optimization model is solved by using a gradient descent method, a Newton method or a constrained optimization method.

[0071] In some optional embodiments, the regularization parameter of the regularization term satisfies the following condition: The deviation is determined based on the first value and the corresponding second value of the target physical quantity, reaches a preset deviation threshold, or is within a preset deviation range.

[0072] 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.

[0073] In some optional embodiments, the target transport kernel function is obtained based on physical experimental result data of different boron concentrations combined with 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.

[0074] In some optional embodiments, the physical experiment is performed based on L groups of energy-angle pairs, L=M×N, the input neutron energy corresponding to the physical experiment is divided into M groups on a logarithmic scale, and the angle corresponding to the physical experiment is divided into N groups.

[0075] 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.

[0076] Further function descriptions of the above-mentioned modules are the same as those of the corresponding embodiments described above, and will not be described here again.

[0077] The neutron source correction device of the radiotherapy planning system in the embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit, Application Specific Integrated Circuit) circuit, a processor and a memory executing one or more software or fixed programs, and / or other devices that can provide the above functions.

[0078] The embodiment of the present application also provides a computer device having the above-mentioned Figure 5 neutron source correction device of the radiotherapy planning system.

[0079] Please refer to Figure 6 , Figure 6 is a structural schematic diagram of a computer device provided by an optional embodiment of the present application, as shown in Figure 6As shown, the computer device includes one or more processors 10, memory 20, and interfaces 30 for external devices such as a keyboard and a mouse and peripheral devices such as disk devices or other storage devices. One or more busses 10 can be used to implement the interface between the various internal and external components and can be implemented using any one or more of a variety of bus technologies including a System bus, PCI, SCSI, AGP, Super- I / O bus, etc. Furthermore, various buses can be used in front side buses, back side buses, and other bus configurations based on any bus or messaging technology known to those skilled in the art. Figure 6 The processor 10 is used in the embodiments below as an example.

[0080] The processor 10 can be a central processing unit, a network processor, or a combination thereof. The processor 10 can further include a hardware chip. The hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device can be a complex programmable logic device, a field programmable logic device, a general array logic, or any combination thereof.

[0081] The memory 20 stores instructions that can be executed by the at least one processor 10, so that the at least one processor 10 implements the method shown in the above embodiments.

[0082] The memory 20 can include a program region and a data region. The program region can store an operating system and an application program required by at least one function. The data region can store data created according to the use of the computer device, etc. In addition, the memory 20 can include a high-speed random access memory, and can further 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 a memory disposed remotely with respect to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0083] The memory 20 can include a volatile memory such as a random access memory, and can also include a non-volatile memory such as a flash memory, a hard disk, or a solid state disk. The memory 20 can further include a combination of the above-mentioned kinds of memories.

[0084] The computer device further includes a communication interface 30 for communication with other devices or communication networks.

[0085] The embodiments of the present application further 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 stored in a remote storage medium or a non-transitory machine readable storage medium and downloaded to a local storage medium through network, 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 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 memories. It can be understood that the computer, the processor, the microprocessor controller, or the programmable hardware includes a storage component that can store or receive software or computer code, when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0086] 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, the method and / or technical solutions according to the present application can be called or provided. 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 file, executable file, installation package file, etc. Correspondingly, 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.

[0087] Although the embodiments of the present application are described in conjunction with the accompanying 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 for a radiotherapy planning system, characterized in that, The method includes: A first value of the target physical quantity obtained based on physical experiment measurements 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; If, based on the first value of the target physical quantity and the corresponding second value, it is determined that the deviation does not meet the preset requirements, then a regularized optimization model is used to invert and obtain the target neutron input energy-angle spectrum so that the deviation meets the preset requirements. Based on the target neutron input energy-angle spectrum, the neutron input energy-angle spectrum in the radiotherapy planning system is corrected.

2. The method according to claim 1, characterized in that, The regularization optimization model includes the deviation between the first value and the corresponding second value, as well as 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 the target transport kernel function, wherein the target transport kernel function is the transport kernel function corresponding to the radiotherapy planning system.

3. The method according to claim 2, characterized in that, The regularization term based on the neutron input energy-angle spectrum is the product of the regularization parameter and the objective function; The objective function is one of the following: The square of the modulus of the neutron input energy-angle spectrum; The square of the modulus 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 absolute error of the neutron input energy-angle spectrum.

4. The method according to claim 3, characterized in that, When the objective function is the square of the modulus of the neutron input energy-angle spectrum, the corresponding regularized optimization model is: ； in, Let be the vector of the target physical quantity obtained from the physical experiment. Input energy-angle spectrum for neutrons, The transport kernel function, This is the regularization parameter.

5. The method according to claim 3, characterized in that, The objective function is: the square of the modulus of the standard deviation matrix of the objective 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: ； in, Let be the vector of the target physical quantity obtained from the physical experiment. Let be the standard deviation matrix of the target transport kernel function. For the smoothing penalty operator, Input energy-angle spectrum for neutrons, The transport kernel function, This is the regularization parameter.

6. The method according to claim 3, characterized in that, When the objective function is the sum of the absolute errors of the neutron input energy-angle spectrum, the corresponding regularized optimization model is: ； in, Let be the vector of the target physical quantity obtained from the physical experiment. Input energy-angle spectrum for neutrons, The transport kernel function, For regularization parameters, Represents energy ,angle The corresponding neutron input energy-angle spectrum, Represents energy ,angle The corresponding neutron input energy-angle spectrum.

7. The method according to claim 2, characterized in that, 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 according to claim 2, characterized in that, The target transport kernel function is obtained by combining physical experimental results data with Monte Carlo simulation based on different boron concentrations. The physical experimental results data with different boron concentrations refer to the results data obtained by conducting physical experiments using water phantoms with different boron concentrations.

9. The method according to claim 1, characterized in that, The physical experiment is based on L sets of energy-angle pairs, where L = M × N. The neutron input energy corresponding to the physical experiment is divided into M sets on a logarithmic scale, and the angle corresponding to the physical experiment is divided into N sets.

10. A computer device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the neutron source correction method of the radiotherapy planning system according to any one of claims 1 to 9.

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