Method, system and terminal for optimizing beam blocker of radiotherapy machine and storage medium

Abstract

The application provides a kind of optimization method, system, terminal and storage medium of radiotherapy machine beam stopper.The method comprises the following steps: constructing the geometric model of radiotherapy machine and radiotherapy machine room; based on the geometric model, according to the beam phase space file and source offset parameter, generate a group of input files of Monte Carlo simulation program, and generate a group of output files by using Monte Carlo simulation calculation; according to a group of output files, determine the dose level of each focus point outside the radiotherapy machine room, and obtain the instantaneous surrounding dose equivalent rate level of each focus point; judge whether there is an excess focus point, if yes, calculate the excess range, update the shape and size of beam stopper, and update the geometric model based on the updated beam stopper, enter the next iteration; if not, output the range and thickness of the beam stopper that needs to be increased in each iteration. The application can not only ensure the shielding effect, but also minimize the weight and reduce the cost.

Description

Technical Field

[0001] This invention relates to the field of radiotherapy machine technology, and in particular to an optimization method, system, terminal and storage medium for a beam deflector in a radiotherapy machine. Background Technology

[0002] Radiation therapy machines typically produce high-energy ionizing radiation (such as X-rays, gamma rays, or electron beams) to treat tumors in patients. Because the ionizing radiation used is high-energy, it usually does not completely attenuate within the patient's body. Instead, it penetrates the body or is scattered at a high angle through the body, resulting in strong ionizing radiation near the beam's main axis after passing through the patient's body. Therefore, it is necessary to attenuate this portion of ionizing radiation to prevent further propagation and harm to the health of medical personnel and the public around the radiation therapy room.

[0003] Because current radiotherapy typically uses multi-angle focusing to irradiate tumors, the direction and range of the beam's main axis vary greatly. Using only the four walls, ceiling, and floor of the radiotherapy room as shielding materials would increase the shielding requirements and construction costs. This is especially true for intraoperative radiotherapy accelerators, which are usually used in operating rooms with high sterility requirements, making modification even more difficult and costly.

[0004] Currently, many radiotherapy machines, especially mobile electron beam intraoperative radiotherapy accelerators, are equipped with beam blockers at the distal end of the beam main axis to shield the intensity of ionizing radiation near the beam main axis after penetrating the patient's body, thereby reducing the shielding requirements of the radiotherapy room. Beam blockers are usually made of heavy metals to provide sufficient attenuation, and therefore are usually quite heavy, making support and counterweighting difficult.

[0005] Currently, radiotherapy machines equipped with beam blockers are simply designed using multi-layered or even single-layered rectangular shielding materials of uniform thickness. This uniform thickness design implicitly assumes that the beam to be blocked is uniform. However, in reality, the forward intensity of the beam is very high, and the dose distribution formed at the distal end is obviously not uniform. A beam blocker of uniform thickness either has insufficient shielding thickness in the central part, making it difficult to guarantee the shielding effect, or excessive shielding thickness in the surrounding parts, unnecessarily increasing the weight and cost of the beam blocker and the entire machine, which is particularly detrimental to the movement and use of the radiotherapy machine during surgery. Summary of the Invention

[0006] This invention provides an optimization method, system, terminal, and storage medium for beam blockers in radiotherapy machines, addressing the problem that existing technologies cannot simultaneously achieve both the shielding effect of beam blockers and reduce weight and cost.

[0007] In a first aspect, embodiments of the present invention provide an optimization method for a beam deflector in a radiotherapy machine, comprising:

[0008] Construct a geometric model of the radiotherapy machine and the radiotherapy room;

[0009] Based on the geometric model, a set of input files for Monte Carlo simulation programs are generated according to the beam phase space file and source offset parameters. Then, a set of output files are generated according to the input files of the Monte Carlo simulation programs.

[0010] Based on a set of output files, the dose levels at each point of interest outside the radiotherapy room are determined, and the instantaneous ambient dose equivalent rate level at each point of interest is obtained based on the dose levels at each point of interest outside the radiotherapy room.

[0011] The system determines whether there is an excess concern point where the instantaneous ambient dose equivalent rate exceeds a preset limit. If so, it calculates the excess range, updates the shape and size of the beam blocker, and updates the geometric model based on the updated beam blocker. It then jumps to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and executes the process iteratively. If not, it outputs the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration.

[0012] Secondly, embodiments of the present invention provide an optimization system for a beam deflector in a radiotherapy machine, comprising:

[0013] The geometry building module is used to build the geometric model of the radiotherapy machine and the radiotherapy room;

[0014] The simulation calculation module is used to generate a set of input files for Monte Carlo simulation programs based on the geometric model, the beam phase space file, and the source offset parameters, and to generate a set of output files based on the input files of the Monte Carlo simulation programs using the Monte Carlo simulation calculation method.

[0015] The results analysis module is used to determine the dose level of each point of interest outside the radiotherapy room based on a set of output files, and to obtain the instantaneous ambient dose equivalent rate level of each point of interest based on the dose level of the point of interest outside the radiotherapy room.

[0016] The evaluation feedback module is used to determine whether there are any excess concerns where the instantaneous ambient dose equivalent rate exceeds a preset limit. If so, it calculates the excess range, updates the shape and size of the beam blocker, and updates the geometric model based on the updated beam blocker. It then jumps to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and executes the process cyclically. If not, it outputs the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration.

[0017] Thirdly, embodiments of the present invention provide a terminal, including a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the optimization method for the beam blocker of a radiotherapy machine as described in the first aspect or any possible implementation thereof.

[0018] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the optimization method for a beam deflector of a radiotherapy machine as described in the first aspect or any possible implementation thereof.

[0019] This invention provides a method, system, terminal, and storage medium for optimizing a beam blocker for a radiotherapy machine. By transforming the optimization problem of the beam blocker's shape and size into an iterative process of accumulating the range and thickness of the beam blocker according to a certain step size, the shape and thickness of the beam blocker are quantitatively optimized. Each iteration reduces the range that needs to be increased in shielding thickness, ultimately forming a beam blocker with a Gaussian distribution-like cross-section, thicker in the middle and thinner at both sides. This ensures the shielding effect while minimizing the volume and weight of the beam blocker, reducing costs, and facilitating the movement and use of the radiotherapy machine during surgery. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the optimization method for the beam blocker of a radiotherapy machine provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the geometric model construction process provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the geometric model provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram illustrating the implementation process of the simulation calculation procedure provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram illustrating the implementation flow of the result parsing process provided in an embodiment of the present invention;

[0026] Figure 6This is a schematic diagram of the average dose level distribution of a single sample at a point of interest under the floor of an intraoperative radiotherapy operating room under passive offset and beam blocker conditions provided in this embodiment of the invention.

[0027] Figure 7 This is a schematic diagram illustrating the implementation process of the evaluation feedback process provided in an embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the excess range radius R of the radiotherapy room floor below the point of interest level projected onto the height of the upper surface of the beam blocker, according to an embodiment of the present invention.

[0029] Figure 9 This is a schematic diagram of the shape of the beam blocker after several iterations provided in an embodiment of the present invention;

[0030] Figure 10 This is a schematic diagram of the single-sample dose level of the radiotherapy machine room floor below the point of interest after several iterations, provided by an embodiment of the present invention.

[0031] Figure 11 This is a flowchart illustrating another optimization method for a beam deflector in a radiotherapy machine provided in an embodiment of the present invention;

[0032] Figure 12 This is a schematic diagram of the structure of the optimized system for the beam deflector of a radiotherapy machine provided in an embodiment of the present invention;

[0033] Figure 13 This is a schematic diagram of the terminal provided in an embodiment of the present invention. Detailed Implementation

[0034] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0036] As the background above indicates, radiotherapy machines equipped with beam blockers are simply designed using multi-layered or even single-layered rectangular shielding materials of uniform thickness. This uniform thickness design implicitly assumes that the beam to be blocked is uniform. However, in reality, the forward intensity of the beam is very high, and the dose distribution formed at the distal end is obviously not uniform. A beam blocker of uniform thickness either has insufficient shielding thickness in the central part, making it difficult to guarantee the shielding effect, or excessive shielding thickness in the surrounding parts, unnecessarily increasing the weight and cost of the beam blocker and the entire machine, which is particularly detrimental to the movement and use of the radiotherapy machine during surgery.

[0037] Furthermore, existing beam blockers must rotate synchronously with the radiation beam source to ensure the beam is always aligned with the center of the beam blocker. While this effectively shields the primary radiation, in some clinical situations, radiotherapy machines need to be deflected at an oblique angle. In this case, the beam blocker rotating concentrically with the gantry would encroach on the patient's treatment space, thus limiting radiotherapy, especially intraoperative radiotherapy. A better solution is to keep the beam blocker moving in a plane parallel to the ground, using a control system to ensure the center of the beam blocker is always aligned with the main axis of the radiation beam emitted from the radiation source, thus guaranteeing the patient's treatment space. Appropriate optimization methods can be used to optimize the shape and size of the beam blocker, minimizing its volume and weight while maintaining shielding effectiveness. Compared to the synchronous rotation of the radiation source and beam blocker, this solution presents a more complex spatial relationship between the beam and the beam blocker, making it more difficult to achieve an optimized shape and size using traditional design methods.

[0038] To address the above problems, this application proposes an optimization method for a beam deflector in a radiotherapy machine. See also... Figure 1 The diagram illustrates a flowchart of the optimization method for a beam blocker in a radiotherapy machine provided in this embodiment of the invention. The entity executing the optimization method for the beam blocker in a radiotherapy machine can be a terminal. The beam blocker is a beam deflector.

[0039] See Figure 1 The optimization method for the aforementioned beam deflector of the radiotherapy machine may include:

[0040] In S101, construct the geometric model of the radiotherapy machine and the radiotherapy room.

[0041] The aforementioned geometric model can be converted from the imported detailed CAD drawings of the radiotherapy machine and radiotherapy room; it can also be quickly established by the user inputting the dimensions, location, and material information of the collimator (and / or light limiter), the patient's virtual water model, the beam blocker, the four walls of the radiotherapy room, the ceiling, and the floor to meet the requirements of radiation protection calculations; the geometric model can also be updated based on the range of increased shielding thickness and the step size of increased shielding thickness required by the beam blocker in the previous iteration.

[0042] In some possible implementations, the above S101 may include:

[0043] Obtain the shape, size, and location information of structures such as the radiotherapy machine and radiotherapy room imported by the user, or manually entered by the user, such as the light-limiting tube, the virtual water model of the patient, and the radiotherapy room.

[0044] Automatically calculate the geometric parameters of the layer of interest outside the radiotherapy room;

[0045] Obtain the source offset parameters input by the user and automatically calculate the center position of the upper surface of the beam blocker;

[0046] The range of shielding thickness needs to be increased for beam blockers that obtain user input or feedback from the previous iteration process;

[0047] Describe the geometric definitions of each structure in the input file of the Monte Carlo simulation program according to the syntax rules of the Monte Carlo simulation program used.

[0048] The geometric model is displayed in three dimensions for visual observation of its geometric definition.

[0049] For this exemplary embodiment of a mobile electron beam intraoperative radiotherapy accelerator, the implementation process of S101 described above can be as follows: Figure 3 As shown:

[0050] (11) Import the CAD drawings of the mobile electron beam intraoperative radiotherapy accelerator and the intraoperative radiotherapy operating room, or input the geometric parameters (such as shape, height, radius, density, material, etc.) of the light-limiting tube, the patient virtual water model, and the intraoperative radiotherapy operating room required for geometric modeling, as well as the installation height of the upper surface of the beam blocker of the mobile electron beam intraoperative radiotherapy accelerator.

[0051] (12). As shown in Table 1, the geometric parameters required for geometric modeling are all set with default values. The geometric parameters of the intraoperative radiotherapy operating room are the minimum dimensions of the operating room for intraoperative radiotherapy as specified in GBZ / T 257-2014 "Radiation Protection Requirements for Intraoperative Radiotherapy with Mobile Electron Accelerators"; the geometric parameters of the light-limiting tube are the maximum light-limiting tube dimensions available in existing radiotherapy machines on the market; the patient virtual water model is a 30cm×30cm×30cm cube water model used to simulate the attenuation and scattering of the original radiation by the patient during treatment; since the default values ​​of the geometric parameters are all the values ​​most unfavorable to shielding, under normal circumstances, the optimized design of the beam blocker of the mobile electron beam intraoperative radiotherapy accelerator obtained by geometric modeling optimization using the default geometric parameters is a conservative value. That is, when other intraoperative radiotherapy operating rooms that meet the national standards and / or use smaller-sized light-limiting tubes, the optimized design of the beam blocker of the mobile electron beam intraoperative radiotherapy accelerator obtained by geometric modeling optimization using the default geometric parameters can also ensure that the ambient dose equivalent rate level of each point of interest under the floor of the intraoperative radiotherapy operating room meets the requirements of the current national standard limit. Users can also define the geometric parameters required for the geometric modeling as needed to meet the design and development needs of new radiotherapy machines.

[0052] Table 1. Default values ​​of geometric parameters required for geometric modeling.

[0053] 1 Light limiter Stainless steel Hollow cylinder Inner diameter: 3.5cm; Outer diameter: 5.0cm; Height: 30cm 2 Patient virtual water model water cube 30cm×30cm×30cm 3 Operating room air Air cuboid 600cm×600cm×350cm 4 Operating room floor C30 concrete cuboid 600cm×600cm×14cm 5 Operating room ceiling C30 concrete cuboid 600cm×600cm×14cm 6 The four walls of the operating room Air cuboid 600cm×350cm×15cm 7 outside air Air cuboid 690cm×690cm×558cm 8 Focus level water cuboid 710cm×710cm×578cm

[0054] (13) In accordance with the current national standard GBZ / T 257-2014 "Radiation Protection Requirements for Intraoperative Radiotherapy with Mobile Electron Accelerators", the location with the highest possible ambient dose equivalent for personnel exposure is selected 30cm outside the outer surface of the dedicated operating room as the focus. Therefore, an additional 30cm of air is added outside the ceiling and four walls of the operating room, with its outer surface serving as the initial focus level. For the space below the intraoperative radiotherapy operating room, assuming its floor height is the same as the intraoperative radiotherapy operating room (350cm), a point 200cm above the ground level is taken as the initial focus level; users can also customize the distance from the isocenter of each focus level or the location of the focus point to adapt to various clinical practice needs.

[0055] (14) Using the initial focus areas outside each wall of the intraoperative radiotherapy operating room as the starting positions, a focus volume with a thickness of 10 cm and made of water was constructed to simulate the possible location of the irradiated human body. The focus volume was uniformly divided, with each voxel having a resolution of 2.5 cm × 2.5 cm × 2.5 cm, which is much smaller than the sensitive volume of the FLUKE 451P detector (300 cm³). 3 .

[0056] (15) Taking the center of the mobile electron beam radiotherapy accelerator as the origin of the machine room (0, 0, 0), and the positive direction of the Z-axis perpendicular to the ground from the origin, the coordinates of each structure in the geometric model are shown in Table 2:

[0057] Table 2 Coordinates of each structure in the geometric model

[0058]

[0059]

[0060] Where R' i Let be the radius of the dose equivalent rate exceeding the limit around each point of interest under the floor of the intraoperative radiotherapy operating room in the i-th iteration feedback, and d be the increase in lead shielding thickness of the moving electron beam intraoperative radiotherapy accelerator beam blocker in each simulation iteration.

[0061] (16) The user inputs the offset angles α and β of the mobile electron beam radiotherapy accelerator gantry and the offset distances Δx, Δy, and Δz, where α and β are the angles of rotation of the mobile electron beam radiotherapy accelerator gantry around the X and Y axes, respectively. The offset angles α and β and the offset distances Δx, Δy, and Δz are used to define the offset state of the original beam in the Monte Carlo simulation program input file. Table 3 gives an example of the range of motion of the mobile electron beam radiotherapy accelerator gantry.

[0062] Table 3. Range of motion of the radiotherapy accelerator gantry during mobile electron beam radiotherapy.

[0063] Offset Angle -30°～+30° -30°～+30° / Offset distance -5cm~+5cm -5cm~+5cm -5cm~+5cm

[0064] (17) Based on the offset angles α, β, γ and offset distances Δx, Δy, Δz of the mobile electron beam radiotherapy accelerator gantry, the position (x, y, z) of the center of the upper surface of the beam blocker of the mobile electron beam radiotherapy accelerator in the plane of the installation height H0 can be calculated by the following formula (1):

[0065]

[0066] (18) After determining the center coordinates of the upper surface of the beam blocker of the mobile electron beam intraoperative radiotherapy accelerator under different source offset states, it is used for geometric modeling of the beam blocker. The larger the original beam offset angle, the larger the projected area on the upper surface of the beam blocker, that is, the beam blocker needs to have a larger shielding area. On the other hand, the more the original beam is translated in the positive Z-axis direction, the smaller the thickness of the patient virtual phantom that it needs to pass through, and the smaller the distance to the beam blocker, which requires the beam blocker to have a thicker shielding thickness. Therefore, considering the symmetry of the entire simulation model in the XY direction, the Monte Carlo simulation can only simulate a few extreme cases in Table 4 to obtain the optimized design of the beam blocker under each extreme case. The maximum shielding area at the same shielding thickness level is taken as the final optimized design of the beam blocker, which can ensure that the beam blocker can reduce the surrounding dose equivalent rate level of the point of interest under the floor of the intraoperative radiotherapy operating room to below the national standard or user-defined limit under all source offset states.

[0067] Table 4 shows several source offset limit cases that require simulation calculations.

[0068]

[0069]

[0070] In summary, taking the Monte Carlo simulation program DosXYZnrc as an example, the geometric definition modules, related geometric parameters, and materials used by each structure in the input file are shown in Table 5:

[0071] Table 5 shows the geometric definition modules, related geometric parameters, and materials used by each structure in the DosXYZnrc input file.

[0072]

[0073] The above structures have containment and being contained relationships, and the system will automatically perform segmentation processing when defining the geometric model.

[0074] (19) The established geometric model is as follows Figure 3 As shown, it can be displayed in three dimensions for visual observation of the model's geometric definition.

[0075] In S102, based on the geometric model, a set of input files for Monte Carlo simulation programs are generated according to the beam phase space file and source offset parameters. Then, using the Monte Carlo simulation calculation method, a set of output files are generated based on the input files of the Monte Carlo simulation programs.

[0076] In some embodiments, the beam phase space file is the phase space file of the beam exit window plane of the radiotherapy machine or the phase space file of the accelerated electrons at the exit of the accelerating tube; the source offset parameters include the gantry rotation angle and translation distance.

[0077] The geometric model can be set according to the location of the phase space file. That is, the beam phase space file can be the phase space file of the beam window plane of the radiotherapy machine. In this case, the geometric model only needs to include structures such as the external light limiter, the patient virtual water model, and the beam blocker. Alternatively, the beam phase space file can be the phase space file of the accelerated electrons at the exit of the accelerator tube. In this case, the geometric model also needs to include detailed structures inside the treatment head such as the target (scattering foil), the monitoring ionization chamber, the primary collimator, and the secondary collimator.

[0078] The source offset parameters include the rack rotation angle and translation distance, which are used to describe the direction of the main beam and calculate the position of the beam blocker.

[0079] In some possible implementations, Monte Carlo parallel computing can be based on commonly used Monte Carlo parallel computing programs such as DosXYZnrc, MCNP, and GEANT4, and can be achieved by using a multi-core processor on a single computing server or by forming a computing cluster with multiple computing servers.

[0080] In some embodiments, S102 may include:

[0081] Obtain the save path of the beam phase space file input by the user;

[0082] Based on the geometric model and save path, the source parameters in the input file of the Monte Carlo simulation program are defined;

[0083] A set of input files for the Monte Carlo simulation program is generated using different initial random numbers;

[0084] Define the source offset state in the input file based on the source offset parameter;

[0085] The Monte Carlo simulation program is called separately for each input file to perform calculations, generating a set of output files for the Monte Carlo simulation program.

[0086] The source parameters in the input file of the Monte Carlo simulation program must be defined in accordance with the syntax rules of the Monte Carlo simulation calculation program.

[0087] In some possible implementations, the Monte Carlo simulation program is called separately for each input file. This can be done in parallel or serial computing methods, without specific limitations. However, to save time and improve efficiency, parallel computing is preferred.

[0088] In a specific embodiment, the implementation process of S102 described above is as follows: Figure 4 As shown, the specific implementation process of the simulation calculation may include:

[0089] (21) Obtain the save path of the phase space file (beam phase space file) of the specific plane of the radiotherapy machine input by the user, which is used to define the source parameters in the Monte Carlo simulation program input file. The phase space file of the specific plane of the radiotherapy machine can be a single file or a set of files obtained from multiple simulations.

[0090] (22). If a single phase space file is used as the source file, then, in combination with the above geometric model, n sets of initial random numbers are used to generate n input files for the Monte Carlo simulation program, where n is the number of parallel computing nodes; if a set of phase space files is used, then n input files for the Monte Carlo simulation program are generated in the same way, and the source file in each file is randomly selected by random numbers, and different initial random numbers are used to start the simulation.

[0091] (23). Define the source offset state in this set of input files according to the source offset parameters input during geometric modeling.

[0092] (24). Call the Monte Carlo simulation program to perform parallel computation for each input file and generate a set of n output files.

[0093] In S103, the dose levels at each point of interest outside the radiotherapy room are determined based on a set of output files and converted to obtain the instantaneous ambient dose equivalent rate level at each point of interest.

[0094] The point of concern outside the radiotherapy room can be defined according to current national radiation protection standards as a level 30cm away from the four walls and ceiling of the room, and the point of concern below the floor (if applicable) at a height of 200cm from the ground floor below. Alternatively, the user can define the point of concern outside the radiotherapy room at a specific distance from the treatment center to suit various clinical practice needs.

[0095] In some embodiments, S103 may include:

[0096] Each output file is parsed to obtain the dose level at the level of interest corresponding to each output file;

[0097] The average dose level of each point of interest is obtained by averaging the dose levels of the corresponding points of interest in each output file.

[0098] The average dose level of each site of interest is converted to obtain the instantaneous ambient dose equivalent rate level of each site of interest.

[0099] In some embodiments, the conversion of the average dose level at each point of interest to obtain the instantaneous ambient dose equivalent rate level at each point of interest includes:

[0100] Obtain the number of particles emitted by the radiotherapy machine per unit time;

[0101] Based on the number of particles, the average dose level of each point of interest is corrected to obtain the instantaneous ambient dose equivalent rate level of each point of interest.

[0102] Among them, the dose levels at various points of interest outside the machine room obtained from the Monte Carlo simulation can be analyzed and displayed in the specific format of the results obtained by the Monte Carlo simulation program by writing programs in programming languages ​​such as Matlab, C++, and Python.

[0103] The dose level at each point of interest can be converted to the instantaneous ambient dose equivalent rate level by using the conversion factor as the ratio of the absorbed dose at a specific depth of the beam with the maximum energy at the maximum dose rate and maximum field of fire under absolute calibration to the average energy deposition of a single particle at that specific depth of interest obtained under the same conditions in Monte Carlo simulation.

[0104] The above-mentioned parsing of each output file yields the dose level at the level of interest corresponding to each output file. This can be done by parsing each output file according to the special format of the Monte Carlo simulation calculation program output file to obtain the dose level at the level of interest corresponding to each output file.

[0105] The dose levels at the corresponding points of interest in each of the above output files can be understood as the single-sample dose levels at the corresponding points of interest in each output file. Averaging these values ​​can reduce the random fluctuations in the Monte Carlo simulation results.

[0106] In a specific embodiment, the implementation process of S103 described above is as follows: Figure 5 As shown, the specific implementation process of result parsing may include:

[0107] (31) Use the written program to parse the set of output files generated above to obtain the average dose level distribution of each point of interest outside the radiotherapy room. Figure 6 The figure shows the single-sample average dose level distribution at the point of interest below the floor of the intraoperative radiotherapy operating room under passive offset and beam blocker conditions in an exemplary embodiment of a mobile electron beam intraoperative radiotherapy accelerator.

[0108] (32). By simulating the single-sample dose level at the calibration location under standard calibration conditions and comparing it with the measured results, the number of particles emitted by the radiotherapy machine per unit time is obtained. The distribution of single-sample dose levels at each point of interest outside the radiotherapy machine room is corrected to obtain the instantaneous ambient dose equivalent rate level of each point of interest under a specific output dose rate.

[0109] Taking an exemplary embodiment of a mobile electron beam intraoperative radiotherapy accelerator as an example, the above conversion process is explained in detail as follows: If the standard calibration conditions are that the water phantom is tightly attached to the lower edge of the light-limiting tube, the accelerator output dose rate is DRcal MU / min, and the beam output is 100 MU, and the measured dose at D cm underwater (generally 2 cm) is 1 Gy, then the above standard measurement conditions can be simulated to obtain the energy deposition of a single particle at D cm underwater as Mcal. Therefore, the beam output time is 100 / DRcal min, and the number of particles N (particles / hour) emitted by the generator per unit time is:

[0110]

[0111] Right now:

[0112]

[0113] If the maximum output dose rate of the mobile electron beam intraoperative radiotherapy accelerator is 300 MU / min, and the maximum single-sampling dose level at each point of interest below the operating room floor is M, then the maximum instantaneous dose rate DR at each point of interest is... M (μSv / h) is:

[0114]

[0115] In S104, it is determined whether there is an excess concern point where the instantaneous ambient dose equivalent rate level exceeds the preset limit. If so, the excess range is calculated, the shape and size of the beam blocker are updated, and the geometric model is updated based on the updated beam blocker. The process then jumps to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and is executed cyclically. If not, the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration are output.

[0116] The preset limit can be either the instantaneous ambient dose equivalent rate level limit specified in the current national radiation protection standards or a user-defined instantaneous ambient dose equivalent rate level limit.

[0117] In some embodiments, the above calculation of excess range, updating the shape and size of the beam blocker, includes:

[0118] Calculate the distance between each excess point of concern and the beam main axis at the intersection point of the point of concern outside the radiotherapy room corresponding to the beam blocker, and take the maximum value of this distance for each excess point of concern as the excess range radius R;

[0119] The excess range radius R is back-projected onto the height of the upper surface of the beam blocker to obtain the range radius R' in which the beam blocker needs to increase the shielding thickness, and the shielding thickness of the beam blocker within this range radius R' is increased according to a preset step size.

[0120] In a specific embodiment, the implementation process of S103 described above is as follows: Figure 7 As shown, the specific implementation process for evaluation and feedback may include:

[0121] (41) Using the ambient dose equivalent rate limit specified in the current national standard or the user-defined limit as the threshold, traverse all points of concern outside the radiotherapy room corresponding to the beam blocker and search for points where the instantaneous ambient dose equivalent rate level exceeds the threshold, i.e., excessive points of concern.

[0122] (42) If there is no point of concern where the instantaneous ambient dose equivalent rate exceeds the threshold, stop the iteration, output the range and thickness of the beam blocker that need to be increased in thickness for each iteration, and output the cross-sectional view of the beam blocker.

[0123] (43) If there are excess concerns where the instantaneous ambient dose equivalent rate exceeds the threshold, calculate the distance between each excess concern and the intersection of the beam main axis at the level of the concern outside the radiotherapy room corresponding to the beam blocker, and take the largest distance as the excess range radius R.

[0124] (44). For example Figure 8 As shown, the maximum radius R of the excess range of the ground-level point of interest is back-projected onto the height of the upper surface of the beam blocker using the principle of similar triangles, thus obtaining the radius R' of the range where the beam blocker needs to increase the shielding thickness.

[0125]

[0126] Where H0 is the installation height of the upper surface of the beam blocker, and H is the height of the point of interest outside the radiotherapy room corresponding to the beam blocker from the origin.

[0127] (45) Feedback the radius R' of the beam blocker where the shielding thickness needs to be increased to S101, and increase the lead shielding thickness of the beam blocker within the radius R' range by a certain step size (e.g., 3 mm). S101 updates the geometric model according to the beam blocker after the shielding is increased, calls the simulation calculation module again to perform Monte Carlo simulation calculation, and calls the evaluation feedback to evaluate the shielding effect. Figure 9 In one exemplary embodiment, the shape of the beam blocker is determined after several iterations. Figure 10 In one exemplary embodiment, the single-sampled dose level of the point of interest below the floor of the radiotherapy room is determined after several iterations. The above steps are repeated continuously, iteratively updating the shielding range and thickness of the beam blocker layer by layer, until the instantaneous ambient dose equivalent rate level of each point of interest outside the radiotherapy room corresponding to the beam blocker meets the requirements of the current national standard limit or the user-defined limit.

[0128] In some embodiments, the optimization method for the above-mentioned beam deflector of the radiotherapy machine further includes:

[0129] Obtain the optimized dimensions of the beam blocker in both the source-no-offset and source-limited-offset states, and take the maximum of the optimized dimensions of the beam blocker in both states as the final size of the beam blocker.

[0130] The source limit offset states can be referred to in Table 4 for different states.

[0131] In a specific application scenario, see Figure 11 The optimization method for the beam blocker of a radiotherapy machine provided in this embodiment may include the following steps:

[0132] (51). Set the installation height of the upper surface of the optimized beam blocker to H0;

[0133] (52). Establish a Monte Carlo simulation geometric model without a beam blocker;

[0134] (53). Combine the phase space file of a specific plane of the radiotherapy machine and the source offset state to generate the input file for the Monte Carlo calculation program;

[0135] (54). Using parallel computing, the Monte Carlo calculation program was used to calculate the dose levels at various points of interest outside the radiotherapy room under the current beam blocker design;

[0136] (55). Analyze the results of Monte Carlo parallel computation and convert them into instantaneous ambient dose equivalent rate distribution;

[0137] (56). According to the protection requirements, if there is no excess concern, stop the iteration, output the excess range R' of each iteration and the corresponding increase in shielding thickness, and output the final beam blocker profile; if there is excess concern, evaluate and determine the excess range, and execute steps (57) to (510).

[0138] (57). Project the excess range back onto the current beam blocker upper surface height to determine the range R' that needs to be further increased in shielding;

[0139] (58). Increase the lead shielding thickness within a certain step size d within the range of the upper surface R' of the current beam blocker;

[0140] (59). Update the current upper surface height of the beam blocker to H0+d;

[0141] (510). Update the simulation geometry model and repeat steps (53) to (510) until the simulation results of the instantaneous ambient dose equivalent rate of all points of interest in step (56) are less than the limit of the current national standard.

[0142] (511). Simulations were performed according to steps (51) to (510) for both source-no-offset and extreme-offset states to obtain the optimized design of the beam blocker for each state. The maximum size of the optimized design of the beam blocker for each state was taken as the final design of the beam blocker for the radiotherapy machine.

[0143] See Table 6, which shows the optimization results obtained using the optimization method for the beam blocker of the radiotherapy machine provided in this application in a certain application scenario.

[0144] Table 6 Optimization results of the beam blocker

[0145]

[0146]

[0147] Table 7 presents a comparison of the final dimensions, volume, and mass of the beam blocker obtained using the optimization method provided in this application and the traditional uniform thickness design method in a certain application scenario to ensure that the dose at each point of interest outside the computer room does not exceed the standard. The results show that the proposed method can significantly reduce the volume and mass of the beam blocker while ensuring the shielding effect, which is more conducive to reducing costs and clinical applications.

[0148] Table 7. Dimensions, volume, and mass of beam blockers obtained using different methods.

[0149] Traditional uniform thickness beam blocker 17.95 50 140978.97 1599.21 The optimization method proposed in this invention 17.95 50 48317.85 548.10

[0150] This application transforms the optimization problem of the beam blocker shape and size for a radiotherapy machine into an iterative process of accumulating the range and thickness of the beam blocker according to a certain step size. This quantitatively optimizes the shape and thickness of the beam blocker. Each iteration reduces the range requiring increased shielding thickness, ultimately forming a beam blocker with a Gaussian-like cross-section—thicker in the middle and thinner at the edges. This ensures effective shielding while minimizing the beam blocker's size and weight, reducing costs, and facilitating the movement of the radiotherapy machine during surgery. Furthermore, the method of this invention can simulate the beam blocker translating at a specific height plane without rotating synchronously with the radiotherapy machine gantry, which helps increase the patient's treatment space and expands the applicability of the radiotherapy machine. Simultaneously, due to the use of parallel computing, this method and system can quickly and accurately obtain the current shielding effect of the beam blocker, improving optimization efficiency.

[0151] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0152] The following are system embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0153] Figure 12 A schematic diagram of the optimized system for a beam deflector in a radiotherapy machine according to an embodiment of the present invention is shown. For ease of explanation, only the parts relevant to the embodiment of the present invention are shown, and are described in detail below:

[0154] like Figure 12 As shown, the optimization system 30 for the beam deflector of a radiotherapy machine may include: a geometry construction module 31, a simulation calculation module 32, a result analysis module 33, and an evaluation feedback module 34.

[0155] The geometry building module 31 is used to build the geometric model of the radiotherapy machine and the radiotherapy room;

[0156] The simulation calculation module 32 is used to generate a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and to generate a set of output files based on the input files of the Monte Carlo simulation program using the Monte Carlo simulation calculation method.

[0157] The result analysis module 33 is used to determine the dose level of each point of interest outside the radiotherapy room based on a set of output files, and to obtain the instantaneous ambient dose equivalent rate level of each point of interest based on the dose level of the point of interest outside the radiotherapy room.

[0158] The evaluation feedback module 34 is used to determine whether there is an excess concern point where the instantaneous ambient dose equivalent rate level exceeds a preset limit. If so, the excess range is calculated, the shape and size of the beam blocker are updated, and the geometric model is updated based on the updated beam blocker. The process then jumps to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and is executed cyclically. If not, the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration are output.

[0159] In one possible implementation, the beam phase space file is either the phase space file of the beam exit window plane of the radiotherapy machine or the phase space file of the accelerated electrons at the exit of the accelerating tube; the source offset parameters include the gantry rotation angle and translation distance.

[0160] In one possible implementation, the simulation calculation module 32 is specifically used for:

[0161] Obtain the save path of the beam phase space file input by the user; define the source parameters in the input file of the Monte Carlo simulation program based on the geometric model and the save path; generate a set of input files for the Monte Carlo simulation program using different initial random numbers; define the source offset state in the input file according to the source offset parameters; call the Monte Carlo simulation program to perform calculations on each input file to generate a set of output files for the Monte Carlo simulation program.

[0162] In one possible implementation, the result parsing module 33 is specifically used for:

[0163] Each output file is parsed to obtain the dose level at the corresponding point of interest. The average dose level at each point of interest is obtained by averaging the dose levels at each output file. The average dose level at each point of interest is then converted to obtain the instantaneous ambient dose equivalent rate at each point of interest.

[0164] In one possible implementation, the result parsing module 33 is also used for:

[0165] The number of particles emitted by the radiotherapy machine per unit time is obtained; based on the number of particles, the average dose level of each point of interest is corrected to obtain the instantaneous ambient dose equivalent rate level of each point of interest.

[0166] In one possible implementation, the evaluation feedback module 34 is also used for:

[0167] Calculate the distance between each excess point of concern and the beam main axis at the intersection point of the point of concern outside the radiotherapy room corresponding to the beam blocker, and take the maximum value of this distance for each excess point of concern as the excess range radius R;

[0168] The excess range radius R is back-projected onto the height of the upper surface of the beam blocker to obtain the range radius R' in which the beam blocker needs to increase the shielding thickness, and the shielding thickness of the beam blocker within this range radius R' is increased according to a preset step size.

[0169] In one possible implementation, the optimization system 30 for the beam deflector of the radiotherapy machine may further include a final optimization module.

[0170] The final optimization module is used to obtain the optimized dimensions of the beam blocker in the source-no-offset state and the source-limited-offset state, and to take the maximum of the optimized dimensions of the beam blocker in the source-no-offset state and the source-limited-offset state as the final dimension of the beam blocker.

[0171] Figure 13 This is a schematic diagram of a terminal provided in an embodiment of the present invention. Figure 13As shown, the terminal 4 in this embodiment includes a processor 40 and a memory 41. The memory 41 stores a computer program 42, and the processor 40 calls and runs the computer program 42 stored in the memory 41 to execute the steps in the above-described embodiments of the optimization method for the beam deflector of various radiotherapy machines, for example... Figure 1 S101 to S104 are shown. Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above system embodiments, for example... Figure 12 The functions of modules / units 31 to 34 shown.

[0172] For example, the computer program 42 can be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 42 in the terminal 4. For example, the computer program 42 can be divided into... Figure 12 Modules / units 31 to 34 are shown.

[0173] The terminal 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 13 This is merely an example of terminal 4 and does not constitute a limitation on terminal 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, the terminal may also include input / output devices, network access devices, buses, etc.

[0174] The processor 40 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0175] The memory 41 can be an internal storage unit of the terminal 4, such as a hard disk or memory of the terminal 4. The memory 41 can also be an external storage device of the terminal 4, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the terminal 4. Furthermore, the memory 41 can include both internal storage units and external storage devices of the terminal 4. The memory 41 is used to store the computer program and other programs and data required by the terminal. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0176] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0177] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0178] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0179] In the embodiments provided by this invention, it should be understood that the disclosed systems / terminals and methods can be implemented in other ways. For example, the system / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0180] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0181] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0182] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above-described optimization method embodiments for the beam deflectors of various radiotherapy machines. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately added to or subtracted from the content as required by the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium may not include electrical carrier signals and telecommunication signals.

[0183] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An optimization method for a beam deflector in a radiotherapy machine, characterized in that, include: Construct a geometric model of the radiotherapy machine and the radiotherapy room; Based on the geometric model, a set of input files for Monte Carlo simulation programs are generated according to the beam phase space file and source offset parameters. Then, a set of output files is generated according to the set of input files for Monte Carlo simulation programs using the Monte Carlo simulation calculation method. Based on the set of output files, the dose level of each point of interest outside the radiotherapy room is determined, and based on the dose level of each point of interest outside the radiotherapy room, the instantaneous ambient dose equivalent rate level of each point of interest is obtained. Determine if there is an excess concern point where the instantaneous ambient dose equivalent rate exceeds a preset limit. If so, calculate the excess range, update the shape and size of the beam blocker, and update the geometric model based on the updated beam blocker. Then, jump to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and execute the process in a loop. If not, output the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration.

2. The method for optimizing the beam deflector of a radiotherapy machine according to claim 1, characterized in that, The beam phase space file is either the phase space file of the beam exit window plane of the radiotherapy machine or the phase space file of the accelerated electrons at the exit of the accelerator tube; the source offset parameters include the gantry rotation angle and translation distance.

3. The method for optimizing the beam deflector of a radiotherapy machine according to claim 1, characterized in that, Based on the geometric model, a set of input files for a Monte Carlo simulation program is generated according to the beam phase space file and source offset parameters. Then, using Monte Carlo simulation calculations, a set of output files is generated based on the input files, including: Obtain the save path of the beam phase space file input by the user; Based on the geometric model and the save path, the source parameters in the input file of the Monte Carlo simulation program are defined; A set of input files for the Monte Carlo simulation program is generated using different initial random numbers; Define the source offset state in the input file based on the source offset parameter; For each input file, a Monte Carlo simulation program is invoked to perform calculations, generating a set of Monte Carlo simulation output files.

4. The method for optimizing the beam deflector of a radiotherapy machine according to claim 1, characterized in that, The step of determining the dose level at each point of interest outside the radiotherapy room based on the set of output files, and obtaining the instantaneous ambient dose equivalent rate level at each point of interest based on the dose level at each point of interest outside the radiotherapy room, includes: Each of the output files is parsed to obtain the dose level at the level of interest corresponding to each output file; The average dose level of each point of interest is obtained by averaging the dose levels of the corresponding points of interest in each output file. The average dose level of each site of interest is converted to obtain the instantaneous ambient dose equivalent rate level of each site of interest.

5. The method for optimizing the beam deflector of a radiotherapy machine according to claim 4, characterized in that, The conversion of the average dose level at each point of interest to obtain the instantaneous ambient dose equivalent rate level at each point of interest includes: The number of particles emitted by the radiotherapy machine per unit time is obtained; Based on the number of particles, the average dose level of each point of interest is corrected to obtain the instantaneous ambient dose equivalent rate level of each point of interest.

6. The method for optimizing the beam deflector of a radiotherapy machine according to claim 1, characterized in that, The calculation of the excess range, updating the shape and size of the beam blocker, includes: Calculate the distance between each excess point of concern and the beam main axis at the intersection point of the point of concern outside the radiotherapy room corresponding to the beam blocker, and take the maximum value of this distance for each excess point of concern as the excess range radius R; The excess range radius R is back-projected onto the height of the upper surface of the beam blocker to obtain the range radius R' in which the beam blocker needs to increase the shielding thickness, and the shielding thickness of the beam blocker within this range radius R' is increased according to a preset step size.

7. The method for optimizing the beam deflector of a radiotherapy machine according to any one of claims 1 to 6, characterized in that, The optimization method for the beam blocker of the radiotherapy machine also includes: Obtain the optimized dimensions of the beam blocker in the source-no-offset state and the source-limited-offset state, and take the maximum of the optimized dimensions of the beam blocker in the source-no-offset state and the source-limited-offset state as the final dimension of the beam blocker.

8. An optimized system for a beam deflector in a radiotherapy machine, characterized in that, include: The geometry building module is used to build the geometric model of the radiotherapy machine and the radiotherapy room; The simulation calculation module is used to generate a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and to generate a set of output files based on the set of input files for the Monte Carlo simulation program using the Monte Carlo simulation calculation method. The result analysis module is used to determine the dose level of each point of interest outside the radiotherapy room based on the set of output files, and to obtain the instantaneous ambient dose equivalent rate level of each point of interest based on the dose level of the point of interest outside the radiotherapy room. The evaluation feedback module is used to determine whether there is an excess concern point where the instantaneous ambient dose equivalent rate level exceeds a preset limit. If so, the excess range is calculated, the shape and size of the beam blocker are updated, and the geometric model is updated based on the updated beam blocker. The process then jumps to the step of generating a set of input files for a Monte Carlo simulation program based on the geometric model, the beam phase space file, and the source offset parameters, and is executed cyclically. If not, output the range and thickness of the beam blocker that need to be increased in shielding thickness for each iteration.

9. A terminal, characterized in that, It includes a processor and a memory, the memory being used to store a computer program, and the processor being used to call and run the computer program stored in the memory to perform the optimization method for the beam deflector of a radiotherapy machine as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the optimization method for the beam blocker of the radiotherapy machine as described in any one of claims 1 to 7.

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