Beam profile determination method, apparatus, and computer-readable storage medium

Abstract

This application relates to a method, apparatus, and computer-readable storage medium for determining beam distribution. For a beam to be modeled, at least two reference directions are determined based on a measured dose distribution; and a target beam distribution of the beam is determined based on at least two reference beam distributions corresponding to the at least two reference directions. This solves the problem of low beam modeling efficiency, improves the speed of modeling calculation, and is applicable to a wider range of application scenarios.

Description

Technical Field

[0001] This application relates to the field of beam dose calculation technology, and in particular to methods, apparatus and computer-readable storage media for determining beam distribution. Background Technology

[0002] In radiotherapy, the beam generated by the treatment head is usually designed to be a regular circle. However, due to numerous unavoidable reasons, the actual beam will deviate from the circle to some extent. For example, the following reasons may cause this: 1. The horizontal and vertical axes of the accelerating tube are asymmetrical, so the accelerated electron beam lacks circular symmetry, resulting in a photon beam that is not circular but may be "elliptical"; 2. Electrons are deflected by a magnetic field before hitting the target, causing electrons of different energies to separate in the magnetic field and ultimately hit different positions on the target, resulting in a photon distribution with more on one side and fewer on the other, resembling an "oval" shape; 3. The target material itself is not uniform, causing the generated photon beam to be non-circular; 4. The photons generated by hitting the target pass through components that lack circular symmetry, such as a rectangular primary collimator, thus losing circular symmetry.

[0003] To model non-circular beams, existing techniques typically simulate every process within the treatment head. For example, they simulate the generation of X-rays, starting with the accelerated electron beam striking the target, and then the beam passing through each stage of the treatment head components before finally delivering the dose to the body. Because all components of the treatment head are simulated, this method can describe non-circular beams caused by various factors.

[0004] However, the above beam distribution has low computational efficiency and is not suitable for application scenarios with high computational speed requirements. Summary of the Invention

[0005] This embodiment provides a method, apparatus, and computer-readable storage medium for determining beam distribution, in order to solve the problem of low computational efficiency of beam distribution in related technologies.

[0006] Firstly, this embodiment provides a method for determining beam distribution, the method comprising:

[0007] For the beam to be modeled, at least two reference directions are determined based on the measured dose distribution;

[0008] The target beam distribution of the beam is determined based on at least two reference beam distributions corresponding to the at least two reference directions.

[0009] In some embodiments, the measured dose distribution includes a two-dimensional measured dose distribution on a two-dimensional plane.

[0010] In some embodiments, determining the target beam distribution of the beam based on at least two reference dose distributions in the at least two reference directions includes:

[0011] Obtain the position weight distribution corresponding to the reference direction;

[0012] Based on the position weight distribution, the distributions of the at least two reference beams are integrated on the two-dimensional plane to obtain the target beam distribution on the two-dimensional plane.

[0013] In some embodiments, based on the position weight distribution, the at least two reference beam distributions are integrated on the two-dimensional plane to obtain a target beam distribution on the two-dimensional plane, including:

[0014] Based on the position weight distribution, the at least two reference beam distributions are integrated on the two-dimensional plane to obtain an initial beam distribution on the two-dimensional plane.

[0015] Based on the initial beam distribution, the predicted dose distribution of the beam is calculated;

[0016] Based on the matching result between the predicted dose distribution and the two-dimensional measured dose distribution, the position weight distribution is adjusted, and based on the adjusted position weight distribution, the reference beam distribution is re-integrated on the two-dimensional plane to obtain the target beam distribution.

[0017] In some embodiments, based on the matching result between the predicted dose distribution and the two-dimensional measured dose distribution, the position weight distribution is adjusted, and based on the adjusted position weight distribution, the reference beam distribution is re-integrated on the two-dimensional plane to obtain the target beam distribution, including:

[0018] Based on the matching result between the predicted dose distribution and the two-dimensional measured dose distribution, the reference beam distribution and the position weight distribution are adjusted, and the predicted dose distribution is recalculated.

[0019] The target beam distribution is obtained until the predicted dose distribution matches the two-dimensional measured dose distribution.

[0020] In some embodiments, the location weight distribution needs to meet preset requirements, which include:

[0021] The position weight distribution applies to the transition region between each of the reference directions.

[0022] In some embodiments, the two-dimensional plane includes a plane that is a predetermined distance from the beam source and perpendicular to the beam direction.

[0023] In some of these embodiments, the determined reference direction includes at least two directions determined based on the axis of symmetry, and / or includes at least two directions that change at different rates in the measured dose distribution.

[0024] Secondly, this embodiment provides a beam distribution determination device, the device comprising:

[0025] The decomposition module is used to determine at least two reference directions for the beam to be modeled, based on the measured dose distribution;

[0026] A reconstruction module is used to determine the target beam distribution of the beam based on at least two reference beam distributions corresponding to the at least two reference directions.

[0027] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the beam distribution determination method described in the first aspect.

[0028] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the beam distribution determination method described in the first aspect.

[0029] Compared with related technologies, the beam distribution determination method, apparatus and computer-readable storage medium provided in this embodiment determine at least two reference directions based on the measured dose distribution for the beam to be modeled; and determine the target beam distribution of the beam based on at least two reference beam distributions corresponding to the at least two reference directions. This solves the problem of low beam modeling efficiency, improves the speed of modeling calculation, and is applicable to a wider range of application scenarios.

[0030] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0032] Figure 1 This is a hardware structure block diagram of the terminal of the beam distribution determination method in one embodiment;

[0033] Figure 2 This is a flowchart illustrating a method for determining beam distribution in one embodiment;

[0034] Figure 3 This is a schematic diagram showing the positional relationship between the two-dimensional plane and the beam source in a preferred embodiment;

[0035] Figure 4 This is a schematic diagram of a one-dimensional distribution of a circular beam in a preferred embodiment;

[0036] Figure 5 This is a schematic diagram of the two-dimensional distribution of a circular beam in a preferred embodiment;

[0037] Figure 6 This is a schematic diagram of the one-dimensional distribution of two reference directions of a non-circular beam in a preferred embodiment;

[0038] Figure 7 This is a schematic diagram of the two-dimensional distribution of a non-circular beam after synthesis in a preferred embodiment;

[0039] Figure 8 This is a schematic diagram of the one-dimensional distribution of two reference directions of a non-circular beam in another preferred embodiment;

[0040] Figure 9 This is a schematic diagram of the two-dimensional distribution of the non-circular beam after synthesis in another preferred embodiment;

[0041] Figure 10 This is a structural block diagram of a beam distribution determination device in one embodiment.

[0042] Reference numerals: 102, processor; 104, memory; 106, transmission device; 108, input / output device; 11, decomposition module; 12, reconstruction module. Detailed Implementation

[0043] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0044] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.

[0045] The method embodiments provided in this example can be executed on a terminal, computer, or similar computing device. For example, it can run on a terminal. Figure 1 This is a hardware structure block diagram of the terminal for the beam distribution determination method in this embodiment. (See diagram for example.) Figure 1 As shown, a terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 and a memory 104 for storing data are also included. The processor 102 may be, but is not limited to, a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that… Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the terminal described above. For example, the terminal may also include components that are larger than... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown are illustrated.

[0046] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the beam distribution determination method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0047] The transmission device 106 is used to receive or send data via a network. This network includes a wireless network provided by the terminal's communication provider. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 can be a Radio Frequency (RF) module used for wireless communication with the Internet.

[0048] This embodiment provides a method for determining beam distribution. Figure 2 This is a flowchart of the beam distribution determination method in this embodiment, as shown below. Figure 2 As shown, the process includes the following steps:

[0049] Step S210: For the beam to be modeled, at least two reference directions are determined based on the measured dose distribution.

[0050] Specifically, the measured dose distribution can be a two-dimensional measurement distribution on a two-dimensional plane. This two-dimensional plane is a pre-defined plane, meaning its positional relationship with the beam source, such as distance and direction, is predetermined. In one embodiment, the two-dimensional plane is a plane at a predetermined distance from the beam source and perpendicular to the beam direction. In other embodiments, the plane containing the two-dimensional plane forms an angle with the plane perpendicular to the beam direction.

[0051] However, this is not the only limitation. For example, the measured dose distribution can also be a three-dimensional measurement distribution within a three-dimensional volume, which can be a pre-defined spatial volume. In one embodiment, the three-dimensional volume is a three-dimensional volume located at a predetermined distance from the beam source and along the beam axis, but the three-dimensional volume can also be set to a volume at other locations.

[0052] Before modeling the beam, it is first measured, specifically the two-dimensional dose distribution on one or more two-dimensional planes or the three-dimensional dose distribution within a three-dimensional volume. In one embodiment, the two-dimensional or three-dimensional dose distribution is acquired, its shape is analyzed, and a reference direction is determined based on this shape. The shape of the two-dimensional dose distribution includes, but is not limited to, the shape of isodose lines and the shape of the distribution of dose points. The shape of the three-dimensional dose distribution includes, but is not limited to, the shape of isodose surfaces and the shape of the distribution of dose points. The reference direction can be determined through mathematical operations such as calculating the axis of symmetry and rate of change of the two-dimensional or three-dimensional dose distribution.

[0053] Step S220: Determine the target beam distribution of the beam based on at least two reference beam distributions corresponding to at least two reference directions.

[0054] Specifically, a reference beam distribution is obtained for each reference direction. This reference beam distribution is an analytical function or discrete numerical table defined by prior knowledge to express the energy distribution, particle number distribution, and other characteristics of the beam. The reference beam distributions from each reference direction are integrated to calculate the values ​​of the transition regions between the reference directions, thus obtaining the complete beam distribution, i.e., the target beam distribution. In one implementation, the analytical function includes, but is not limited to, a one-dimensional function f(r) related to position r, or a multi-dimensional joint function f(E,r), f(p,r), f(E,v,r) of energy E, momentum p, velocity v, and position r, to express the distribution of physical quantities such as particle number flux, particle energy flux, and kerma in the beam. Therefore, the definition of the reference beam distribution differs in different algorithm models. Based on the selected reference beam distribution, a corresponding type of target beam distribution can be synthesized to represent the particle flux distribution or energy flux distribution of the beam. Once the target beam distribution is determined, dose calculation or information analysis can be performed based on the target beam distribution, and the calculation or analysis results can be applied to different scenarios such as the debugging of radiotherapy equipment or the design of radiotherapy plans.

[0055] In this embodiment, for the beam to be modeled, at least two reference directions are determined based on the measured dose distribution; based on the at least two reference beam distributions corresponding to the at least two reference directions, the target beam distribution of the beam is determined, which solves the problem of low beam modeling efficiency. By setting simple beam distributions in several directions, and then integrating them into a complete target beam distribution, the decomposition of the beam distribution is realized, thereby reducing the workload of beam modeling, improving the calculation speed, and being suitable for various application scenarios where the beam presents a circle or deviates from a regular circle.

[0056] The following mainly uses the example of measuring a dose distribution that is or includes a two-dimensional dose distribution on a two-dimensional plane to illustrate a non-limiting example of steps S210 and S220. However, it is not limited to this. The method described below can also be extended to the case where the dose distribution is or includes a three-dimensional dose distribution in a three-dimensional volume, which will not be elaborated here.

[0057] In some embodiments, based on step S220 above, the target beam distribution of the beam is determined based on at least two reference dose distributions in at least two reference directions, including:

[0058] Step S221: Obtain the position weight distribution corresponding to the reference direction.

[0059] Step S222: Based on the position weight distribution, integrate at least two reference beam distributions on a two-dimensional plane to obtain the target beam distribution on the two-dimensional plane.

[0060] Specifically, the position weight distribution represents the correspondence between each position (x, y) on a two-dimensional plane and its corresponding weight. It can employ a weight function or a discrete weight table. The position weight distribution is used to adjust the beam distribution during the transition from one reference direction to another, thereby connecting the various reference beam distributions.

[0061] In some embodiments, based on step S220 above, and based on the position weight distribution, at least two reference beam distributions are integrated on a two-dimensional plane to obtain a target beam distribution on the two-dimensional plane, including:

[0062] Step S310: Based on the position weight distribution, integrate at least two reference beam distributions on a two-dimensional plane to obtain an initial beam distribution on the two-dimensional plane.

[0063] Step S320: Calculate the predicted dose distribution of the beam based on the initial beam distribution.

[0064] Step S330: Based on the matching results of the predicted dose distribution and the two-dimensional measured dose distribution, the position weight distribution is adjusted. Based on the adjusted position weight distribution, the reference beam distribution is re-integrated on the two-dimensional plane to obtain the target beam distribution.

[0065] Specifically, when comparing measurement results, certain directions can be selected, and only the dose distribution in these directions can be compared. Common choices are to compare the dose distribution along the x-axis, y-axis, and diagonals at 45 degrees and 135 degrees. Preferably, the dose distribution along a reference direction is selected for comparison.

[0066] In some cases, even with a relatively simple beam shape, technicians may still be unable to construct a suitable weighting function that matches the dose transition shape between different reference directions to the measurement results. In such cases, technicians can increase the number of reference directions and improve the shape of the dose distribution transitioning from one reference direction to another by reducing the span between adjacent reference directions.

[0067] In this embodiment, based on the decomposed beam, the accuracy of the target beam distribution is improved through continuous comparison and adjustment.

[0068] In some embodiments, based on the matching results of the predicted dose distribution and the two-dimensional measured dose distribution, the position weight distribution is adjusted, and based on the adjusted position weight distribution, the reference beam distribution is re-integrated on the two-dimensional plane to obtain the target beam distribution, including:

[0069] Step S410: Based on the matching results between the predicted dose distribution and the two-dimensional measured dose distribution, adjust the reference beam distribution and the position weight distribution, and recalculate the predicted dose distribution.

[0070] Step S420 continues until the predicted dose distribution matches the two-dimensional measured dose distribution, thus obtaining the target beam distribution.

[0071] Specifically, along each reference direction, a reference beam distribution f is defined. i (r), where i = 1, 2, ... represents each reference direction, and the formula... (x,y) is an arbitrary position vector on a two-dimensional plane.

[0072] Define the weight function w between (x, y) and each reference direction. i (x,y). When the algorithm needs to calculate the beam distribution at any position vector (x,y) on a two-dimensional plane, the following formula is used:

[0073]

[0074] Where f(x,y) is the target dose distribution, w i (x,y) is a weighting function for a certain reference direction, f i (r) represents the reference beam distribution in a certain reference direction.

[0075] The f(x,y) defined in the above steps is used as input for dose calculation. The calculation result is compared with the measurement result, and f is continuously adjusted. i (r) and w i (x,y) until the calculation matches the measurement result.

[0076] In practical applications, condition f can be applied simultaneously.i (r) and w i (x,y), we can also consider f i (r) and w i (x,y) is separated, and only f is adjusted each time the predicted dose distribution is updated. i (r), or only adjust w i (x,y).

[0077] In this embodiment, through f i (r) and w i The dual adjustment of (x,y) further improves the accuracy of the target beam distribution and reduces the requirements for the selection of the reference beam distribution in the initial stage. For example, in the case of a common irregular beam distribution, the center of the irregular beam still has circular symmetry, while the beam exhibits a non-circular shape only near the edge. If the reference beam distribution set in the initial stage cannot accurately construct the target beam distribution, it is only necessary to adjust f in each direction during the adjustment stage. i (r) is equal when r is close to the beam center, while f in all directions i (r) The difference only needs to exist when r is near the edge of the beam. This allows for gradual optimization of the reference beam distribution in subsequent adjustments, making the calculation process more flexible and simple.

[0078] In the above example, r is defined as the radial distance from any point (x,y) on the plane to the beam center. However, in actual use, the origin of the coordinate system used to define r can also be chosen as a point other than the beam center.

[0079] In some of these embodiments, the determined reference directions include at least two directions determined based on the axis of symmetry.

[0080] Specifically, common beam distributions include "elliptical" and "oval" shapes. "Elliptical" doesn't necessarily refer to a strictly mathematically defined ellipse, but rather broadly refers to various shapes where one axis is stretched and at least one other orthogonal axis is flattened; "oval" can broadly refer to various shapes where one direction increases while the other decreases. For "elliptical" and "oval" beam distributions, they can be approximated as standard ellipses, with their major axis as one reference direction and their minor axis as another, or based on an inherent axis of symmetry, with the positive direction on the axis of symmetry as one reference direction and the negative direction as another.

[0081] In some of these embodiments, the determined reference directions include at least two directions that change at different rates in the measured dose distribution.

[0082] Specifically, for non-standard irregular beam distributions such as "elliptical" or "oval", the rate of change of beam distribution along each direction in the two-dimensional or three-dimensional dose distribution can be calculated, and the transformation directions with different rates of change can be used as reference directions.

[0083] In some embodiments, the determined reference direction may include a direction determined by at least one axis of symmetry and at least one direction determined based on the rate of change. A more suitable reference direction can be determined based on the actual situation of the beam.

[0084] In some of these embodiments, the position weight distribution needs to meet preset requirements, including that the position weight distribution applies to the transition region between each reference direction.

[0085] Specifically, since the purpose of setting the position weight distribution is to control the shape of the dose distribution when transitioning from one reference direction to another, and the specific values ​​in the reference directions are determined by the reference beam distribution, when acquiring or constructing the position weight distribution, it is necessary to consider that each position weight distribution does not act on the reference direction, but only on the transition region, even if f(x,y) is taken as fx(r) on the x-axis and fy(r) on the y-axis. On the other hand, the position weight distribution needs to ensure a smooth transition of f(x,y) between each reference direction.

[0086] The present embodiment will now be described and illustrated through preferred embodiments.

[0087] To improve the speed of dose calculation, clinically used dose calculation software abstracts and simplifies the treatment head. In dose calculation, algorithms typically omit the beam generation process within the treatment head, as well as the initial processes the beam undergoes, such as passing through the primary collimator, homogenizer, and ionization chamber. The algorithm does not simulate these processes. Instead, it models the beam distribution after these processes using empirical analytical functions or numerical tables. After obtaining the beam distribution through modeling, the algorithm only needs to simulate the subsequent processes the beam undergoes, typically including the trimming and hardening of the beam as it passes through the tungsten gate and multi-leaf collimator, and the energy deposition process after entering the body.

[0088] Modeling the beam distribution, i.e. calculating the beam distribution, is a key step in the above process.

[0089] Since the beam generated by the treatment head is typically circular, its circular symmetry is usually assumed when modeling it, and a one-dimensional function f(r) is used to describe the circularly symmetric beam distribution. Depending on the algorithm, f(r) may refer to the particle number flux, particle energy flux, kerma of the beam, etc., or it may refer to other physical quantities of the particles, such as energy E, momentum p, or velocity v, combined with position r, i.e., f(E,r), f(p,r), f(E,v,r), etc. The dependence of f on r may be given by empirical analytical formulas or by discrete numerical tables. Here, f(r) is defined on a specific two-dimensional plane perpendicular to the beam centerline. r is the radial distance from any point (x,y) on this plane to the beam center, i.e.

[0090] See Figure 3 Here, the distance from the two-dimensional plane to the beam source is L. Since the beam distribution is inversely proportional to the square of L when L is large, the beam distribution on planes where L equals other values ​​can be calculated by specifying f(r) on a single plane. Therefore, f(r) is always defined on a specific plane. For machines with isocenters, f(r) is typically defined on the isocenter plane.

[0091] Since this preferred embodiment mainly involves the extension of the beam distribution from circular to non-circular, in the following text, we focus on discussing the distribution form of f on a given two-dimensional plane, and will no longer discuss the dependence of f on L.

[0092] To model a beam, tools such as water tanks, phantoms, films, and flat plates are typically used to measure the dose distribution of the beam within these materials. These dose distributions are inherently three-dimensional, but usually only a subset of points, lines, or planes are selected for beam modeling. For example, the dose curve along the depth distribution on the beam's centerline can be used to model the beam's energy spectrum; while the dose distribution on a plane perpendicular to the beam direction can be used to model the beam's shape.

[0093] When modeling f(r), people usually select some planes at a specific depth that are perpendicular to the beam direction, and then use f(r) as the input of the algorithm to calculate the dose distribution on these planes and compare it with the measurement results. Then, they continuously adjust f(r) until the calculation matches the measurement results.

[0094] Here, if f(r) is given in the form of an analytical formula, then the modeling process is to adjust the parameters in the analytical formula; if f(r) is given in the form of a numerical table, then the modeling process is to adjust each number in the table.

[0095] Undoubtedly, since the beam described by f(r) has circular symmetry, the dose distribution calculated from it in a homogeneous material must also have circular symmetry. Therefore, when comparing with measurement results, people usually do not compare the dose distribution across the entire two-dimensional plane, but rather select specific directions and compare only the dose distribution along those directions. Common choices are to compare the dose distribution along the x-axis, y-axis, and diagonals at 45 degrees and 135 degrees.

[0096] Once f(r) is given, it can be used as input to the algorithm for dose calculation. If the algorithm needs to calculate the f value at any position (x, y) on a two-dimensional plane, it only needs to calculate... Then you can substitute it into f(r) for calculation. As an example, Figure 4 It shows a one-dimensional function f(r), and Figure 5 This shows the two-dimensional distribution reconstructed from the function, i.e.

[0097] The above describes the modeling process for circular beams. For non-circular beams, this preferred embodiment further proposes the following method:

[0098] 1. Select two or a few specific directions on a two-dimensional plane, called "reference directions". Then model the beam distribution along these reference directions.

[0099] 2. For any vector in the two-dimensional plane, define a weighting function between the vector and each of the aforementioned reference directions. Then, use these weighting functions to synthesize the beam distributions in each reference direction into a beam distribution across the entire two-dimensional plane.

[0100] This preferred embodiment proposes a non-circular beam modeling method that describes the non-circular beam distribution by extending a one-dimensional function f(r) to beam distributions in two or a few specific directions and defining a weighting function between an arbitrary position vector and these directions. In this preferred embodiment, when adjusting the beam distribution in each reference direction, it is only necessary to compare the dose distribution in that reference direction.

[0101] Next, as two preferred examples, descriptions of the "elliptical" and "oval" beam distributions of this preferred embodiment are presented respectively.

[0102] For an "elliptical" beam distribution, we assume the major axis of the ellipse is the x-axis in a two-dimensional plane, and the minor axis is the y-axis. Based on the symmetry of the ellipse, we can easily choose its major and minor axes as reference directions. Since the ellipse is symmetrical about the left and right and up and down along its major and minor axes respectively, we only need to model the beam distribution along the positive x-axis and positive y-axis, denoted as f, respectively. x (r) and f y (r). In order to make f x (r) and f y (r) is synthesized into a two-dimensional beam distribution f(x,y). We define a weighting function between an arbitrary position vector (x,y) on the two-dimensional plane and two reference directions, denoted as w. x (x,y) and w y (x, y). We take the functional form of the two functions as w respectively. x (x,y)=x 2 and w y (x,y)=y 2 Then, the beam distribution on the two-dimensional plane can be obtained according to the above formula (1).

[0103] Here, when constructing two weighting functions, technicians need to rely on experience to select their functional forms to meet certain specific requirements. For example, the two weighting functions should make f(x,y) take the value f on the x-axis. x (r), while f is taken on the y-axis. y (r); In addition, the two weighting functions should make f(x,y) symmetric about the x-axis and y-axis; for example, when f(x,y) transitions between the x-axis and y-axis, its shape should be natural and smooth, conforming to people's perception of "ellipse", and making the dose calculation results consistent with the measurement. Figure 6 It demonstrates a kind of f x (r) and f y Specific regulation of (r), and Figure 7 The two-dimensional distribution synthesized using the above method is shown.

[0104] For the "oval" beam distribution, we assume that the central axis of the oval shape is the y-axis in the two-dimensional plane. That is, the oval shape is asymmetrical in the positive and negative directions of the y-axis, but symmetrical about the y-axis. Based on this symmetry, we choose the positive and negative directions of the y-axis as reference directions, and denote the beam distribution in the two reference directions as f. + (r) and f - (r).

[0105] In order to f + (r) and f -(r) is synthesized into a two-dimensional beam distribution f(x,y). We define a weighting function between an arbitrary position vector (x,y) on the two-dimensional plane and two reference directions, denoted as w. + (x,y) and w - (x, y). We take the functional form of the two functions as w respectively. + (x,y)=(r+y) 2 and w - (x,y)=(ry) 2 Then, the beam distribution on the two-dimensional plane can be obtained according to formula (1).

[0106] Here, the two weighting functions have certain requirements, such as: the two weighting functions should make f(x,y) take the value f on the positive half of the y-axis. + (r), while f is taken on the negative half-axis of y. - (r); In addition, the two weighting functions should make f(x,y) symmetrical about the y-axis; for example, when f(x,y) transitions between the positive and negative half-axis of the y-axis, its shape should be natural and smooth, conforming to people's perception of "oval shape", and making the dose calculation results consistent with the measurement.

[0107] Figure 8 It demonstrates a kind of f + (r) and f - Specific regulation of (r), Figure 9 The two-dimensional distribution synthesized using the above method is shown.

[0108] The above examples only demonstrate the method for modeling "elliptical" and "oval" beam distributions. However, any person with some experience can easily apply the method proposed in this invention to model beam distributions of other shapes.

[0109] Those skilled in the art should understand that any algorithmic model must strike a balance between its complexity and accuracy. Therefore, when the method of this invention is used for beam modeling, even if the calculated dose distribution does not perfectly match the measurement results, the effectiveness of this method should be accepted as long as the difference is within an acceptable range.

[0110] The beam modeling method proposed in this preferred embodiment is simple, requires less modeling work for non-circular beams, and has higher operability.

[0111] This embodiment also provides a beam distribution determination device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. The terms "module," "unit," "subunit," etc., used below can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0112] Figure 10 This is a structural block diagram of the beam distribution determination device in this embodiment, as shown below. Figure 10 As shown, the device includes a decomposition module 11 and a reconstruction module 12.

[0113] Decomposition module 11 is used to determine at least two reference directions for the beam to be modeled based on the measured dose distribution.

[0114] Reconstruction module 12 is used to determine the target beam distribution of the beam based on at least two reference beam distributions corresponding to at least two reference directions.

[0115] In some embodiments, the reconstruction module 12 is further configured to obtain the position weight distribution corresponding to the reference direction; based on the position weight distribution, integrate at least two reference beam distributions on a two-dimensional plane corresponding to the two-dimensional measurement dose distribution to obtain the target beam distribution on the two-dimensional plane.

[0116] In some of these embodiments, the two-dimensional plane includes a plane that is a predetermined distance from the beam source and perpendicular to the beam direction.

[0117] In some of these embodiments, the determined reference directions include at least two directions determined based on the axis of symmetry.

[0118] In some of these embodiments, the determined reference directions include at least two directions that change at different rates in the measured dose distribution.

[0119] In some embodiments, the reconstruction module 12 is further configured to integrate at least two reference beam distributions on a two-dimensional plane based on the position weight distribution to obtain an initial beam distribution on the two-dimensional plane; calculate the predicted dose distribution of the beam based on the initial beam distribution; adjust the position weight distribution based on the matching result between the predicted dose distribution and the two-dimensional measured dose distribution; and re-integrate the reference beam distributions on the two-dimensional plane based on the adjusted position weight distribution to obtain the target beam distribution.

[0120] In some embodiments, the reconstruction module 12 is further configured to adjust the reference beam distribution and position weight distribution based on the matching result of the predicted dose distribution and the two-dimensional measured dose distribution, and recalculate the predicted dose distribution until the predicted dose distribution matches the two-dimensional measured dose distribution to obtain the target beam distribution.

[0121] In some of these embodiments, the position weight distribution needs to meet preset requirements, including that the position weight distribution applies to the transition region between each reference direction.

[0122] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0123] This embodiment also provides a computer device, including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0124] Optionally, the computer device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0125] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated in this embodiment.

[0126] Furthermore, in conjunction with the beam distribution determination method provided in the above embodiments, this embodiment can also provide a storage medium for implementation. The storage medium stores a computer program; when executed by a processor, the computer program implements any of the beam distribution determination methods in the above embodiments.

[0127] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0128] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0129] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or independent of other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0130] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A beam profile determination method, characterized by, The method comprises: determining at least two reference directions based on a measured dose distribution for a beam to be modeled; determining a target beam distribution of the beam based on at least two reference beam distributions corresponding to the at least two reference directions.

2. The beam profile determination method of claim 1, wherein, The measured dose distribution comprises a two-dimensional measured dose distribution on a two-dimensional plane.

3. The beam profile determination method of claim 2, wherein, The determining of the target beam distribution of the beam based on the at least two reference dose distributions in the at least two reference directions comprises: obtaining a position weight distribution corresponding to the reference directions; integrating the at least two reference beam distributions on the two-dimensional plane based on the position weight distribution to obtain a target beam distribution on the two-dimensional plane.

4. The beam profile determination method of claim 3, wherein, The integrating of the at least two reference beam distributions on the two-dimensional plane based on the position weight distribution to obtain a target beam distribution on the two-dimensional plane comprises: integrating the at least two reference beam distributions on the two-dimensional plane based on the position weight distribution to obtain an initial beam distribution on the two-dimensional plane; calculating a predicted dose distribution of the beam based on the initial beam distribution; adjusting the position weight distribution based on a matching result of the predicted dose distribution and the two-dimensional measured dose distribution, and re-integrating the reference beam distributions on the two-dimensional plane based on the adjusted position weight distribution to obtain the target beam distribution.

5. The beam profile determination method of claim 4, wherein, The adjusting of the position weight distribution based on the matching result of the predicted dose distribution and the two-dimensional measured dose distribution, and the re-integrating of the reference beam distributions on the two-dimensional plane based on the adjusted position weight distribution to obtain the target beam distribution comprises: adjusting the reference beam distributions and the position weight distribution based on the matching result of the predicted dose distribution and the two-dimensional measured dose distribution, and recalculating the predicted dose distribution; until the predicted dose distribution matches the two-dimensional measured dose distribution, the target beam distribution is obtained.

6. The beam profile determination method of claim 3, wherein, The position weight distribution satisfies a preset requirement, and the preset requirement comprises: the position weight distribution acts on a transition region between each of the reference directions.

7. The beam profile determination method of claim 2, wherein, The two-dimensional plane comprises a plane that is perpendicular to a beam direction and has a preset length from a beam source.

8. The beam profile determination method of claim 1, wherein, The determined reference directions comprise at least two directions determined based on a symmetry axis, and / or comprise at least two directions having different variation speeds in the measured dose distribution.

9. A beam profile determination apparatus, characterized in that The apparatus comprises: a decomposition module configured to determine at least two reference directions based on a measured dose distribution for a beam to be modeled; a reconstruction module configured to determine a target beam distribution of the beam based on at least two reference beam distributions corresponding to the at least two reference directions.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program, when executed by a processor, implements the steps of the beam distribution determination method of any one of claims 1 to 8. The computer program, when executed by a processor, implements the steps of the beam distribution determination method of any one of claims 1 to 8.

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