Method for simulating particle transport and related equipment

Abstract

The invention discloses a method for simulating particle transport and related equipment, and relates to the technical field of radiotherapy, and the method comprises the steps: constructing an equivalent density model along a particle transport direction based on the structure parameters of an energy regulator combination, and building a matched boundary information table, the boundary information table at least records the position information of the downstream boundary of each energy regulator piece in the energy regulator combination, the equivalent water thickness accumulated from the incident end to the boundary, and the air gap length between the boundary and the upstream boundary of the next energy regulator piece; obtaining a particle current position and boundary information table; the medium area where the current free path of the particles is located is judged, and differential calculation is carried out on offset generated by movement of the particles in different areas according to the medium area until the particles pass through the energy regulator combination to be transported; according to the method, rapid and accurate judgment and differential offset calculation of the boundary are realized, so that the boundary processing complexity is remarkably reduced and the calculation efficiency is improved on the premise of ensuring the physical simulation precision when the particles pass through the energy regulator.

Description

Technical Field

[0001] This invention relates to the field of radiotherapy technology, and more particularly to methods and related equipment for simulating particle transport. Background Technology

[0002] In a particle therapy system equipped with a range shifter (RS), the accuracy of the dose distribution calculation of the particle beam directly determines the therapeutic effect. The prerequisite for accurate dose distribution calculation is to accurately simulate the energy, position, and secondary particle distribution of the particles after passing through the range shifter assembly.

[0003] Existing particle transport simulation technologies suffer from significant complexity and inefficiency when dealing with modulator combinations, making it difficult to meet the dual demands of clinical treatment for simulation accuracy and speed. On the one hand, modulator combinations are flexible and varied, with multiple combinations of modulator elements in terms of quantity and specifications, and the relative positions of each element can be dynamically adjusted according to treatment needs. This makes it impossible to adapt to different modulator combination conditions by pre-calculating and storing transport results, requiring real-time particle transport simulation for each configuration, which significantly increases computation time.

[0004] On the other hand, air gaps inevitably exist between the various tuner plates in the tuner assembly. The motion deflection law and range attenuation characteristics of particles in the air gaps are fundamentally different from those inside the tuner plate material. This requires that each gap boundary be physically processed and calculated separately during the simulation process.

[0005] Traditional Monte Carlo simulations typically employ a step-by-step, iterative approach when dealing with material boundaries. That is, as a particle approaches the boundary, it moves incrementally with extremely small, fixed step sizes, continuously checking whether it has crossed the interface, and switching the physical model and resetting parameters accordingly after crossing. This process is not only computationally complex but also introduces multiple conditional checks and iterations, becoming the main time-consuming part of the entire transport simulation. Furthermore, it is prone to simulation errors due to inappropriate step size settings; too large a step size leads to inaccurate boundary identification, while too small a step size exponentially increases the computational load, further exacerbating the time consumption problem and severely restricting the clinical application efficiency and dosage calculation accuracy of particle therapy systems. Summary of the Invention

[0006] Based on the above problems, the purpose of this invention is to provide a method and related equipment for simulating particle transport. By constructing an equivalent density model along the particle transport direction and establishing a corresponding boundary information table, the invention enables rapid and accurate boundary judgment and differential offset calculation. This significantly reduces the complexity of boundary processing and improves computational efficiency while ensuring the accuracy of physical simulation when particles pass through the energy tuner.

[0007] In a first aspect, the present invention provides a method for simulating particle transport, comprising:

[0008] Based on the structural parameters of the tuner assembly, an equivalent density model along the particle transport direction is constructed, and a corresponding boundary information table is established. The boundary information table records at least the position information of the downstream boundary of each tuner piece in the tuner assembly, the equivalent water thickness accumulated from the incident end to the boundary, and the air gap length between the boundary and the upstream boundary of the next tuner piece.

[0009] During the simulation of a particle passing through a tuner, the particle's current position and boundary information table are used to determine the medium region where the particle's current free path is located. Based on this, the offset generated by the particle's movement in different regions is calculated differently until the particle completes the transport of the tuner assembly.

[0010] Preferably, the structural parameters of the tuner assembly include the thickness of each tuner plate and its position in the beam direction; the construction of the equivalent density model along the particle transport direction includes:

[0011] One-dimensional density distribution data is generated based on the position and thickness of each tuner plate. The data corresponding to the region where a tuner plate is present is the density value of the tuner plate material, and the data corresponding to the region where no tuner plate is present is the density value of air.

[0012] Preferably, establishing the corresponding boundary information table includes: based on the one-dimensional density distribution data, parsing out the position identifier of the downstream boundary of each effective tuner chip in the data; and recording the position identifier as the boundary position information in the boundary information table.

[0013] Preferably, establishing the corresponding boundary information table includes:

[0014] For each valid tuner chip in the tuner assembly, create a record in the boundary information table;

[0015] Each record contains at least:

[0016] Boundary location information, which is the location identifier of the downstream boundary of the effective tuner chip in the equivalent density model;

[0017] The cumulative equivalent water thickness is the sum of the equivalent water thicknesses of all tuner plates traversed from the particle incident end to the downstream boundary; and,

[0018] The air gap length is the distance between the downstream boundary and the upstream boundary of the next adjacent effective tuner plate;

[0019] The effective energy adjuster slice refers to the non-empty energy adjuster slice participating in particle energy adjustment in the current energy adjuster combination.

[0020] Preferably, the method for obtaining the cumulative equivalent water thickness includes:

[0021] For each effective energy adjuster slice, calculate the equivalent water thickness of the energy adjuster slice according to its thickness and material density;

[0022] In the order of the energy adjuster slices in the beam direction, accumulate the equivalent water thicknesses of all previous effective energy adjuster slices to obtain the equivalent water thickness accumulated to the current downstream boundary.

[0023] Preferably, the method for determining the medium region where the current free path of the particle is located through the current position of the particle and the boundary information table and differentially calculating the offset generated by the particle moving in different regions includes:

[0024] Obtain the equivalent water thickness w1 at the starting position of the current free path of the particle and the equivalent water thickness w2 at the ending position;

[0025] Query the boundary information table to obtain the equivalent water thickness w corresponding to the downstream boundary of the effective energy adjuster slice;

[0026] If w1 < w < w2 is satisfied, it is determined that the current free path of the particle passes through the downstream boundary of the effective energy adjuster slice, and the movement offset of the particle is the sum of the scattering physical offset in the medium of the energy adjuster slice and the offset in the air gap;

[0027] If w1 < w < w2 is not satisfied, it is determined that the current free path of the particle does not cross the downstream boundary of the effective energy adjuster slice, and the movement offset of the particle is the scattering physical offset determined based on the medium property of the energy adjuster slice and the path length.

[0028] Preferably, the calculation method of the offset in the air gap includes:

[0029] Establish a three-dimensional coordinate system with the particle transport direction as the Z direction, and determine the three-dimensional unit vector of the particle movement direction in the energy adjuster slice;

[0030] Obtain the air gap length corresponding to the current downstream boundary by querying the boundary information table;

[0031] Divide the air gap length by the component of the particle movement direction on the Z axis to obtain the number of movement steps of the particle in the Z direction in the air gap;

[0032] Multiply the number of movement steps by the three-dimensional unit vector of the particle movement direction to obtain the offset of the particle in the air gap;

[0033] The offset in the air gap is a pure geometric offset, without considering the influence of medium scattering and energy attenuation.

[0034] Preferably, the calculation method of the scattering physical offset includes:

[0035] Obtain the material density of the current energy modulator slice from the equivalent density model;

[0036] Determine the movement path length of the particle inside the energy modulator slice;

[0037] If w1 < w < w2, the equivalent water thickness corresponding to the path length is w - w1. Determine the free path scaling coefficient through the material density of the energy modulator slice, and convert the free path corresponding to the equivalent water thickness into the actual movement path length inside the energy modulator slice;

[0038] If w1 < w < w2 is not satisfied, the path length is the complete free path length of the particle inside the energy modulator slice; Taking the particle incident energy, the material density of the energy modulator slice, and the actual movement path length as inputs, call the physical model of particle multiple Coulomb scattering and energy loss to calculate the scattering physical offset inside the energy modulator slice medium.

[0039] In a second aspect, the present invention provides an electronic device for simulating the transport process of particles in a target energy modulator. The electronic device includes a memory and at least one processor. The memory stores a computer program, and the at least one processor is configured to perform the following steps when executing the computer program:

[0040] Based on the structural parameters of the energy modulator combination, construct an equivalent density model along the particle transport direction, and establish a supporting boundary information table. The boundary information table records at least the position information of the downstream boundary of each energy modulator slice in the energy modulator combination, the equivalent water thickness accumulated from the incident end to this boundary, and the air gap length between this boundary and the upstream boundary of the next energy modulator slice;

[0041] During the process of simulating the particle passing through the energy modulator, through the particle current position and the boundary information table; judge the medium region where the particle current free path is located, and accordingly perform differential calculation on the offset generated by the particle movement in different regions until the particle completes the transport through the energy modulator combination.

[0042] In a third aspect, the present invention provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by at least one processor, it implements the steps of the method described in the embodiments of the present invention or implements the functions of the electronic device described in the embodiments of the invention.

[0043] In a fourth aspect, the present invention provides a computer program product. The computer program product includes a computer program, and when the computer program is executed by at least one processor, it implements the steps of the method described in the embodiments of the invention or implements the functions of the electronic device described in the embodiments of the invention.

[0044] Fifthly, the present invention provides a radiotherapy system, comprising:

[0045] An apparatus for simulating particle transport is used to match simulated dose distribution information of particles with desired dose distribution information using the simulated particle transport method described in the embodiments of the present invention.

[0046] A device for determining human dose, used to determine the simulated dose as the dose used in radiotherapy after matching the simulated dose distribution information of the particles with the desired dose distribution information.

[0047] Compared with existing technologies, the beneficial effects of this invention include at least the following: by constructing an equivalent density model along the particle transport direction and establishing a corresponding boundary information table, rapid and accurate boundary judgment and differential offset calculation are achieved, eliminating the need for fixed step-size point-by-point verification. The boundary and related parameters are directly located through the boundary information table, significantly reducing the complexity of boundary processing between the tuner plate and the air gap, and avoiding the error risk caused by unreasonable step-size settings; relying on the differential offset calculation of accurate medium properties provided by the equivalent density model, both the scattering physical characteristics of particles within the tuner plate and the geometric motion characteristics within the air gap are taken into account, effectively ensuring the accuracy of physical simulation; by quickly querying the boundary information table instead of point-by-point verification, the amount of computation is significantly reduced, and the efficiency of particle transport simulation is greatly improved. It can be flexibly adapted to different tuner combinations and position adjustment conditions, meeting the dual requirements of clinical particle therapy for simulation accuracy and efficiency. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a method for simulating particle transport according to an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the particle transport process according to an embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram of a radiotherapy system in an embodiment of the present invention. Detailed Implementation

[0051] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0052] The terms used to express position and direction in this invention are illustrated with reference to the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0053] Example 1, refer to Appendix Figure 1 and attached Figure 2 This embodiment provides a method for simulating particle transport, including:

[0054] Based on the structural parameters of the tuner assembly, an equivalent density model along the particle transport direction is constructed, and a corresponding boundary information table is established. This boundary information table records at least the downstream boundary of each tuner chip in the tuner assembly (see reference). Figure 2 The location information (at the orange line in the middle), the equivalent water thickness accumulated from the incident end to the boundary, and the length of the air gap between the boundary and the upstream boundary of the next tuner plate;

[0055] During the simulation of a particle passing through a tuner, the particle's current position and boundary information from the boundary information table are used to determine the medium region where the particle's current path of freedom is located. Differential calculations are then performed on the offset generated by the particle's movement in different regions until the particle completes its transport through the tuner assembly. The particle can be a proton or a heavy ion.

[0056] The structural parameters of the energy modulator assembly include the individual energy modulator chips (see...). Figure 2 The thickness of RS (as indicated in the diagram) and its position in the beam direction (see reference). Figure 2 The position indicated by the blue line with arrows; the construction of the equivalent density model along the particle transport direction includes:

[0057] One-dimensional density distribution data is generated based on the position and thickness of each tuner plate. The data corresponding to the region where a tuner plate is present is the density value of the tuner plate material, and the data corresponding to the region where no tuner plate is present is the density value of air.

[0058] The establishment of the corresponding boundary information table includes: based on the one-dimensional density distribution data, parsing out the position identifier of the downstream boundary of each effective tuner chip in the data; and recording the position identifier as the boundary position information in the boundary information table.

[0059] The effects of the above technical solution are as follows:

[0060] An equivalent density model is accurately constructed using one-dimensional density distribution data. This model, combined with a boundary information table, directly parses and records key boundary parameters, replacing the traditional fixed-step, point-by-point verification method. This significantly simplifies boundary processing logic, fundamentally avoiding simulation errors caused by improper step size settings and reducing boundary processing complexity. The equivalent density model can accurately distinguish the density attributes of the tuner plate and the air region, providing precise medium parameter support for differentiated offset calculations and ensuring the accuracy of particle transport physics simulations. The boundary information table enables rapid querying of boundary parameters without point-by-point verification or repetitive calculations, significantly reducing computational load and improving simulation efficiency. It also allows for flexible adjustments to the number, specifications, and position of tuner plates, meeting the needs of different tuner combinations and aligning with the dual requirements of simulation accuracy and efficiency in clinical particle therapy.

[0061] In this embodiment, an equivalent density model along the particle transport direction is constructed based on the structural parameters of the tuner assembly (including the thickness of each tuner plate and its position in the beam direction). The generation of the one-dimensional density distribution data is based on the positional distribution of each tuner plate in the tuner assembly. Discrete sampling is performed along the Z-axis of particle transport (i.e., the particle transport direction) to generate a series of sampling points. A corresponding density value is assigned according to the material region where each sampling point is located, forming a one-dimensional array. Among them, the geometric positions of the upstream and downstream boundaries of each effective tuner plate in the tuner assembly are used as necessary sampling points to generate a non-equidistant one-dimensional density array. If the material properties of the regions between adjacent sampling points are the same, no additional sampling points are inserted. Furthermore, the array index of this one-dimensional equivalent density model has a linear mapping relationship with the geometric position on the actual particle motion path.

[0062] Simultaneously, based on the one-dimensional density distribution data, a corresponding boundary information table is parsed and established. Specifically, this includes: traversing the one-dimensional equivalent density model, identifying abrupt changes in density values ​​from the tuner material density to air density, and recording each abrupt change point index as a downstream boundary index; calculating the equivalent water thickness contributed by all tuner plates from the incident end to each abrupt change point (i.e., the sum of the converted product of the thickness of the current tuner plate and all previous effective tuner plates with their corresponding densities), as the cumulative equivalent water thickness; when calculating the air gap length, using the downstream boundary position identifiers corresponding to two adjacent records in the boundary information table, combined with the sampling interval of the one-dimensional density distribution data, calculating the distance between the downstream boundary of the current effective tuner plate and the upstream boundary of the next effective tuner plate. If it is the last effective tuner plate, the air gap length is recorded as 0 or a null value.

[0063] During the simulation of a particle passing through a tuner, the particle's current position is combined with the boundary data in the boundary information table to determine the medium region where the particle's current free path is located. Differentiated calculations are performed for the offset generated by the particle's motion in different regions. The corresponding distance the particle moves in the air gap is determined by the difference between the particle's current Z-axis coordinate and the Z-axis coordinate of the downstream boundary of the tuner plate recorded in the boundary information table. This offset is a purely geometric offset. The offset of the particle within the tuner plate is calculated based on the tuner plate density, particle energy, and motion path length until the particle completes the transport of the tuner assembly.

[0064] The effects of the above technical solution are as follows:

[0065] One-dimensional density distribution data employs non-equidistant sampling, setting necessary sampling points only at the boundaries of the tuner plate. This balances model accuracy with data volume. Combined with the linear mapping relationship between digital indexes and geometric positions, it enables rapid and accurate querying of medium properties. By integrating a boundary information table, downstream boundaries are directly located through density abrupt change points, completely replacing traditional fixed-step point-by-point verification. This significantly simplifies boundary processing logic, fundamentally avoiding simulation errors caused by improper step size settings and significantly reducing boundary processing complexity. The equivalent density model accurately distinguishes the density attributes of the tuner plate and air regions. The cumulative equivalent water thickness is calculated through multi-plate superposition to ensure data accuracy. This provides precise parameter support for calculating the differentiated offset of particles within the tuner plate (based on density, energy, and path length) and within the air gap (based on coordinate differences), maximizing the accuracy of particle transport physics simulations. The boundary information table enables one-stop, rapid querying of boundary parameters, cumulative equivalent water thickness, and air gap length, eliminating the need for point-by-point verification and repetitive calculations, significantly reducing computational load and improving simulation efficiency. Meanwhile, the non-equidistant sampling and flexible boundary resolution logic can adapt to dynamic adjustments in the number, specifications, and position of tuner plates, meeting the needs of different tuner combinations and perfectly matching the dual requirements of simulation accuracy and efficiency in clinical particle therapy.

[0066] In one possible implementation, establishing the corresponding boundary information table includes:

[0067] For each valid tuner chip in the tuner assembly, create a record in the boundary information table;

[0068] Each record contains at least:

[0069] Boundary location information, which is the location identifier of the downstream boundary of the effective tuner chip in the equivalent density model;

[0070] The cumulative equivalent water thickness is the sum of the equivalent water thicknesses of all tuner plates traversed from the particle incident end to the downstream boundary; and,

[0071] The air gap length is the distance between the downstream boundary and the upstream boundary of the next adjacent effective tuner plate;

[0072] The effective tuner plate refers to the non-empty tuner plate in the current tuner assembly that participates in particle energy regulation.

[0073] The effects of the above technical solution are as follows:

[0074] Each effective tuner chip is individually documented, ensuring a clear recording logic in the boundary information table. All core parameters (boundary location, cumulative equivalent water thickness, air gap length) correspond one-to-one, avoiding parameter confusion and improving the convenience of boundary information retrieval and retrieval. Dedicated records accurately link the downstream boundaries and associated parameters of a single effective tuner chip, eliminating the need for additional derivation or conversion. This lays the foundation for quickly determining the medium region where the particle's path of freedom resides, simplifying the boundary processing flow from the outset. The recording rules adapt to the non-idle characteristics and combined operating conditions of the effective tuner chips, allowing for flexible addition or removal of records based on the dynamic adjustment of the number and location of the tuner chips. This ensures compatibility with different tuner combinations and strong versatility.

[0075] In one possible implementation, the method for obtaining the cumulative equivalent water thickness includes:

[0076] For each effective tuner plate, the equivalent water thickness of the tuner plate is calculated based on its thickness and material density.

[0077] Based on the order of the tuner plates in the beam direction, the equivalent water thickness of all previously effective tuner plates is accumulated to obtain the equivalent water thickness accumulated to the current downstream boundary.

[0078] The equivalent water thickness is obtained by the following formula:

[0079] Equivalent water thickness = physical thickness of tuner plate × (density of tuner plate material / density of water).

[0080] The effects of the above technical solution are as follows:

[0081] Based on the direct conversion of the physical thickness and material density of the energy adjuster sheet, combined with a clear formula, it ensures the calculation accuracy of the equivalent water thickness of a single energy adjuster sheet, provides a reliable basis for subsequent cumulative values, and avoids the conduction of parameter errors. In the way of cumulative addition in the beam direction sequence, it accurately matches the particle transport path and the arrangement rule of the energy adjuster sheets, so that the cumulative equivalent water thickness can truly reflect the equivalent effect of the medium experienced by the particles from the incident end to the current downstream boundary, and provides accurate parameter support for the regional judgment and offset calculation in subsequent particle transport simulation. The formula-based and step-by-step acquisition process does not require additional complex derivation, can quickly adapt to effective energy adjuster sheets of different materials and different thicknesses, is compatible with the dynamic adjustment conditions of the energy adjuster combination, and improves the applicability and operability of the method. Fourth, the calculation process of this method is simple, without redundant operations, can efficiently generate cumulative equivalent water thickness data, adapts to the rapid construction requirements of the boundary information table, and does not increase the calculation burden of the overall simulation process.

[0082] In a possible implementation manner, the method for judging the medium region where the current free path of the particle is located through the current position of the particle and the boundary information table, and differentially calculating the offset generated by the particle moving in different regions includes:

[0083] Obtain the equivalent water thickness w1 at the starting position of the current free path of the particle and the equivalent water thickness w2 at the ending position;

[0084] Query the boundary information table to obtain the equivalent water thickness w corresponding to the downstream boundary of the effective energy adjuster sheet;

[0085] If w1 < w < w2 is satisfied, it is determined that the current free path of the particle passes through the downstream boundary of the effective energy adjuster sheet, and the movement offset of the particle is the sum of the scattering physical offset in the medium of the energy adjuster sheet and the offset in the air gap;

[0086] If w1 < w < w2 is not satisfied, it is determined that the current free path of the particle does not cross the downstream boundary of the effective energy adjuster sheet, and the movement offset of the particle is the scattering physical offset determined based on the medium property and path length of the energy adjuster sheet.

[0087] In a possible implementation manner, the calculation method of the offset in the air gap includes:

[0088] Establish a three-dimensional coordinate system with the particle transport direction as the Z direction, and determine the three-dimensional unit vector of the particle movement direction in the energy adjuster sheet;

[0089] Obtain the air gap length corresponding to the current downstream boundary by querying the boundary information table;

[0090] Divide the air gap length by the component of the particle movement direction on the Z axis to obtain the number of movement steps of the particle in the Z direction in the air gap;

[0091] Multiply the number of movement steps by the three-dimensional unit vector of the particle movement direction to obtain the offset of the particle within the air gap;

[0092] The offset within the air gap is a pure geometric offset, without considering the effects of medium scattering and energy attenuation.

[0093] In a possible implementation, the calculation method of the scattering physical offset includes:

[0094] Obtain the material density of the current energy modulator sheet from the equivalent density model;

[0095] Determine the movement path length of the particle inside the energy modulator sheet;

[0096] If w1 < w < w2, the equivalent water thickness corresponding to the path length is w - w1. Determine the free path scaling coefficient through the material density of the energy modulator sheet, and convert the free path corresponding to the equivalent water thickness into the actual movement path length inside the energy modulator sheet;

[0097] If w1 < w < w2 is not satisfied, the path length is the complete free path length of the particle inside the energy modulator sheet; taking the particle incident energy, the material density of the energy modulator sheet, and the actual movement path length as inputs, call the physical model of particle multiple Coulomb scattering and energy loss to calculate the scattering physical offset inside the medium of the energy modulator sheet.

[0098] Traditional methods rely on real-time comparison of particle positions and geometric boundaries, and require repeated distance calculations and conditional judgments. This embodiment innovatively introduces a physical quantity of equivalent water thickness as a judgment medium. Specifically:

[0099] In the preprocessing stage, the corresponding cumulative equivalent water thickness w has been calculated for the downstream boundary of each effective energy modulator sheet and recorded in the boundary information table. During the simulation run, for a free path of a particle, only the equivalent water thicknesses w1 and w2 at its starting point and ending point need to be obtained.

[0100] By simply numerically comparing w1 < w < w2, it can be directly and deterministically judged whether this free path crosses the boundary of a certain energy modulator sheet, transforming the complex spatial geometry crossing problem into an efficient numerical magnitude comparison problem.

[0101] Once it is determined that the free path crosses the boundary, this embodiment does not use a single model for approximation. Instead, according to different physical processes, the total displacement is decomposed into an in-material part and an air-gap part, and the most applicable models are respectively used for precise calculation and then synthesized:

[0102] Calculation of displacement in material: Corresponding to the equivalent water thickness segment from w to w1 (i.e., the part before the boundary),

[0103] Using the formula Calculations are performed; where, (w - w1) is the equivalent water thickness difference, which is divided by the material density or multiplied by a scaling factor based on density and composition to convert it into the actual physical action length in the material, and then multiplied by the unit vector in the direction of motion (direction) to obtain the physical offset dominated by scattering and energy loss, ensuring the physical accuracy of transport in the material.

[0104] Air gap displacement calculation: Corresponding to the air gap part after the boundary.

[0105] Using the formula Calculations are performed. Where, air_gap is the geometric length of the air gap directly queried from the boundary information table, and direction.z is the component of the particle motion direction along the beam axis (Z direction). This calculation is purely based on geometric relationships, assuming that the particle moves in a straight line in a vacuum along the original direction without considering scattering and energy loss, thus efficiently and accurately describing the behavior of the particle in the gap.

[0106] Total displacement: It is the vector superposition of the displacements of the above two parts, that is

[0107]

[0108] If it is judged that w1 < w < w2 does not hold (that is, the free path is completely within a single energy tuner slice), then the offset is directly calculated using the scattering physical model based on the medium properties of the energy tuner and the complete path length, and the process is simple.

[0109] Due to the possible density differences in different energy tuner slices, an accurate calculation method calculates the proportion of the particle's free path in the adjacent two energy tuner slices to obtain the corresponding displacement. Here, for the sake of description convenience, it is simplified.

[0110] In addition, since the thickness of the energy tuner slices is more than 1 mm and the particle's free path is also 1, the situation where the free path of a single particle passes through multiple energy tuner slices does not need to be considered.

[0111] The effects of the above technical solutions are as follows:

[0112] Traditional Monte Carlo simulations need to use extremely small step sizes for iterative trials at the boundary to accurately locate, resulting in a large amount of computational overhead. This method can complete the boundary judgment through a one-time numerical comparison of w1 < w < w2, completely eliminating the iterative process, which is the key to efficiency improvement.

[0113] The complex transport across boundaries is decomposed into two independent displacement calculations with a single model (material physics model + air geometry model), and then synthesized. The logic is clear, avoiding the complexity of mixing different physical processes within a single step. All core parameters required for the calculation (equivalent water thickness w at the boundary, air gap length air_gap) can be obtained instantaneously by directly querying a pre-generated boundary information table, resulting in extremely high data access efficiency. The method based on equivalent water thickness essentially measures the path using physical action (water equivalent) rather than geometric step size, thus accurately capturing boundary crossing events occurring within the free path and avoiding errors introduced by "crossing" the boundary with a fixed step size.

[0114] By strictly distinguishing and applying scattering / energy loss models in materials and pure geometric rectilinear propagation models in air, the correct simulation of physical mechanisms in both media is ensured. The displacements of the two parts are calculated separately using physical formulas and then vectorized. The results are far more accurate than equating the air gap to a certain material or performing other approximations, especially when traversing the gap multiple times, where the cumulative error is significantly reduced. The core of the entire boundary treatment is simplified to table lookup -> numerical comparison -> formula calculation; this greatly reduces the complexity of code implementation and maintenance, making the algorithm more robust. Traditional methods require a trade-off between accuracy and efficiency in step size. This method is insensitive to the free path length (step size), and even with larger step sizes, the accuracy of boundary treatment can be guaranteed through the above mechanism, thus giving the simulation setup greater flexibility. The method is based on a boundary information table, which can be dynamically generated according to the structural parameters of any combination of tuners. Therefore, this method can automatically adapt to tuners of different thicknesses, numbers, and arrangements without any modification, providing excellent versatility and engineering practicality.

[0115] Example 2: This application also provides an electronic device for simulating the transport process of particles in a target energy tuner. The electronic device includes a memory and at least one processor. The memory stores a computer program, and the at least one processor is configured to execute the computer program to perform the following steps:

[0116] Based on the structural parameters of the tuner assembly, an equivalent density model along the particle transport direction is constructed, and a corresponding boundary information table is established. The boundary information table records at least the position information of the downstream boundary of each tuner piece in the tuner assembly, the equivalent water thickness accumulated from the incident end to the boundary, and the air gap length between the boundary and the upstream boundary of the next tuner piece.

[0117] During the simulation of a particle passing through a tuner, the particle's current position and boundary information table are used to determine the medium region where the particle's current free path is located. Based on this, the offset generated by the particle's movement in different regions is calculated differently until the particle completes the transport of the tuner assembly.

[0118] The structural parameters of the tuner assembly include the thickness of each tuner plate and its position in the beam direction; the construction of the equivalent density model along the particle transport direction includes:

[0119] One-dimensional density distribution data is generated based on the position and thickness of each tuner plate. The data corresponding to the region where a tuner plate is present is the density value of the tuner plate material, and the data corresponding to the region where no tuner plate is present is the density value of air.

[0120] The establishment of the corresponding boundary information table includes: based on the one-dimensional density distribution data, parsing out the position identifier of the downstream boundary of each effective tuner chip in the data; and recording the position identifier as the boundary position information in the boundary information table.

[0121] The establishment of the corresponding boundary information table includes:

[0122] For each valid tuner chip in the tuner assembly, create a record in the boundary information table;

[0123] Each record contains at least:

[0124] Boundary location information, which is the location identifier of the downstream boundary of the effective tuner chip in the equivalent density model;

[0125] The cumulative equivalent water thickness is the sum of the equivalent water thicknesses of all tuner plates traversed from the particle incident end to the downstream boundary; and,

[0126] The air gap length is the distance between the downstream boundary and the upstream boundary of the next adjacent effective tuner plate;

[0127] The effective tuner plate refers to the non-empty tuner plate in the current tuner assembly that participates in particle energy regulation.

[0128] When the at least one processor is configured to execute the computer program, it obtains the cumulative equivalent water thickness through the following steps:

[0129] For each effective tuner plate, the equivalent water thickness of the tuner plate is calculated based on its thickness and material density.

[0130] Based on the order of the tuner plates in the beam direction, the equivalent water thickness of all previously effective tuner plates is accumulated to obtain the equivalent water thickness accumulated up to the current downstream boundary.

[0131] When the at least one processor is configured to execute the computer program, the medium region where the current mean free path of the particle is located is determined by the following steps, and the offsets generated by the particle moving in different regions are calculated differentially, including:

[0132] Obtain the equivalent water thickness w1 at the starting position of the current mean free path of the particle and the equivalent water thickness w2 at the ending position;

[0133] Query the boundary information table to obtain the equivalent water thickness w corresponding to the downstream boundary of the effective energy conditioner sheet;

[0134] If w1 < w < w2 is satisfied, it is determined that the current mean free path of the particle passes through the downstream boundary of the effective energy conditioner sheet, and the movement offset of the particle is the sum of the scattering physical offset in the medium of the energy conditioner sheet and the offset in the air gap;

[0135] If w1 < w < w2 is not satisfied, it is determined that the current mean free path of the particle does not cross the downstream boundary of the effective energy conditioner sheet, and the movement offset of the particle is the scattering physical offset determined based on the medium property of the energy conditioner sheet and the path length.

[0136] The calculation method of the offset in the air gap includes:

[0137] Establish a three-dimensional coordinate system with the particle transport direction as the Z direction, and determine the three-dimensional unit vector of the particle movement direction in the energy conditioner sheet;

[0138] Obtain the air gap length corresponding to the current downstream boundary by querying the boundary information table;

[0139] Divide the air gap length by the component of the particle movement direction on the Z axis to obtain the number of movement steps of the particle in the Z direction in the air gap;

[0140] Multiply the number of movement steps by the three-dimensional unit vector of the particle movement direction to obtain the offset of the particle in the air gap;

[0141] The offset in the air gap is a pure geometric offset, without considering the influence of medium scattering and energy attenuation.

[0142] The calculation method of the scattering physical offset includes:

[0143] Obtain the material density of the current energy conditioner sheet from the equivalent density model;

[0144] Determine the movement path length of the particle inside the energy conditioner sheet;

[0145] If w1 < w < w2, the equivalent water thickness corresponding to the path length is w - w1. Determine the mean free path scaling coefficient through the material density of the energy conditioner sheet, and convert the mean free path corresponding to the equivalent water thickness into the actual movement path length inside the energy conditioner sheet;

[0146] If \(w1 < w < w2\) is not satisfied, the path length is the complete free path length of the particle within the energy modulator slice; taking the incident energy of the particle, the material density of the energy modulator slice, and the actual movement path length as inputs, the physical model of particle multiple Coulomb scattering and energy loss is called to calculate the scattering physical offset within the medium of the energy modulator slice.

[0147] The working principle, effect, and implementation of the above technical solution are the same as those in Embodiment 1 and will not be elaborated here.

[0148] The embodiment of the present application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by at least one processor, it implements the steps of the method described in Embodiment 1 or the functions of the electronic device described in Embodiment 2. The specific implementation manner is consistent with the implementation manner and the achieved technical effects recorded in the above method embodiment, and some content will not be elaborated.

[0149] In the present invention, the readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, device, or component. The program product can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0150] Computer-readable storage media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The readable storage medium may also be any readable medium capable of sending, propagating, or transmitting a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, or any suitable combination thereof. Program code for performing operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar programming languages. The program code may be executed entirely on a user computing device, partially on an associated device, as a standalone software package, partially on a user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing devices can be connected to user computing devices via any type of network, including local area networks (LANs) or wide area networks (WANs), or they can be connected to external computing devices (e.g., via the Internet using an Internet service provider).

[0151] This application also provides a computer program product, which includes a computer program that, when executed by at least one processor, implements the steps of the method described in Embodiment 1 or the function of the electronic device described in Embodiment 2.

[0152] This application also provides a radiotherapy system, including:

[0153] An apparatus for simulating particle transport, used to match simulated dose distribution information of particles with desired dose distribution information using the simulated particle transport method described in Example 1;

[0154] A device for determining human dose, used to determine the simulated dose as the dose used in radiotherapy after matching the simulated dose distribution information of the particles with the desired dose distribution information.

[0155] The radiotherapy system also includes a particle accelerator 200 for providing a beam and a treatment head 300 for docking with the particle accelerator and allowing the beam to pass through; the particle accelerator has a beam outlet 201, and the treatment head has a first end near the particle accelerator beam outlet and a second end opposite to the first end; the treatment head has an energy modulator assembly 301 and a collimator 302 near the second end for adjusting the beam, and the treatment head 300 also includes a scanning magnet 303 for adjusting the beam deflection direction.

[0156] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for simulating particle transport, characterized in that, Comprising: Based on the structural parameters of the energy adjuster combination, an equivalent density model along the particle transport direction is constructed, and a supporting boundary information table is established. The boundary information table records at least the position information of the downstream boundary of each energy adjuster sheet in the energy adjuster combination, the equivalent water thickness accumulated from the incident end to this boundary, and the air gap length between this boundary and the upstream boundary of the next energy adjuster sheet; During the process of simulating the particle passing through the energy adjuster, through the current position of the particle and the boundary information table, judge the medium region where the current free path of the particle is located, and calculate the offset generated by the particle moving in different regions differentially until the particle completes the transport through the energy adjuster combination.

2. The method for simulating particle transport according to claim 1, characterized in that, The structural parameters of the energy adjuster combination include the thickness of each energy adjuster sheet and its position in the beam direction; the construction of the equivalent density model along the particle transport direction includes: According to the positions and thicknesses of each energy adjuster sheet, one-dimensional density distribution data is generated. Among them, the data corresponding to the region where there is an energy adjuster sheet is the density value of the material of this energy adjuster sheet, and the data corresponding to the region where there is no energy adjuster sheet is the density value of air.

3. The method for simulating particle transport according to claim 2, characterized in that, The establishment of the supporting boundary information table includes: based on the one-dimensional density distribution data, parsing out the position identifier of the downstream boundary of each effective energy adjuster sheet in the data; using the position identifier as the boundary position information and recording it in the boundary information table.

4. The method for simulating particle transport according to claim 1, characterized in that, The establishment of the supporting boundary information table includes: For each effective energy adjuster sheet in the energy adjuster combination, create a record in the boundary information table; Among them, each record contains at least: Boundary position information, which is the position identifier corresponding to the downstream boundary of this effective energy adjuster sheet in the equivalent density model; Accumulated equivalent water thickness, which is the sum of the equivalent water thicknesses of all passed energy adjuster sheets from the particle incident end to this downstream boundary; and, Air gap length, which is the distance between this downstream boundary and the upstream boundary of the next adjacent effective energy adjuster sheet; The effective energy adjuster sheet refers to the non-empty energy adjuster sheet participating in particle energy adjustment in the current energy adjuster combination.

5. The method for simulating particle transport according to claim 1, characterized in that, The method for obtaining the accumulated equivalent water thickness includes: For each effective energy adjuster sheet, calculate the equivalent water thickness of this energy adjuster sheet according to its thickness and material density; In the order of this energy adjuster sheet in the beam direction, accumulate the equivalent water thicknesses of all previous effective energy adjuster sheets to obtain the equivalent water thickness accumulated to the current downstream boundary.

6. The method for simulating particle transport according to claim 1, characterized in that, The determination of the medium region where the current free path of the particle is located through the current position of the particle and the boundary information table, and the differential calculation of the offset generated by the particle moving in different regions includes: Obtain the equivalent water thickness w1 at the starting position of the current free path of the particle and the equivalent water thickness w2 at the ending position; Query the boundary information table to obtain the equivalent water thickness w corresponding to the downstream boundary of the effective energy adjuster sheet; If w1 < w < w2 is satisfied, it is determined that the current free path of the particle passes through the downstream boundary of this effective energy adjuster sheet, and the movement offset of the particle is the sum of the scattering physical offset in the medium of the energy adjuster sheet and the offset in the air gap; If \(w1 < w < w2\) is not satisfied, it is determined that the current mean free path of the particle does not cross the downstream boundary of the effective energy conditioner sheet, and the movement offset of the particle is the scattering physical offset determined based on the medium properties of the energy conditioner sheet and the path length.

7. The method for simulating particle transport according to claim 6, characterized in that, The calculation method of the offset within the air gap includes: Establish a three-dimensional coordinate system with the particle transport direction as the Z direction, and determine the three-dimensional unit vector of the particle movement direction within the energy conditioner sheet; Obtain the air gap length corresponding to the current downstream boundary by querying the boundary information table; Divide the air gap length by the component of the particle movement direction on the Z axis to obtain the number of movement steps of the particle in the Z direction within the air gap; Multiply the number of movement steps by the three-dimensional unit vector of the particle movement direction to obtain the offset of the particle within the air gap; The offset within the air gap is a pure geometric offset, without considering the effects of medium scattering and energy attenuation.

8. The method for simulating particle transport according to claim 6, characterized in that, The calculation method of the scattering physical offset includes: Obtain the material density of the current energy conditioner sheet from the equivalent density model; Determine the movement path length of the particle within the energy conditioner sheet; If \(w1 < w < w2\), the equivalent water thickness corresponding to the path length is \(w - w1\). Determine the mean free path scaling coefficient through the material density of the energy conditioner sheet, and convert the mean free path corresponding to the equivalent water thickness into the actual movement path length within the energy conditioner sheet; If \(w1 < w < w2\) is not satisfied, the path length is the complete mean free path length of the particle within the energy conditioner sheet; taking the particle incident energy, the material density of the energy conditioner sheet, and the actual movement path length as inputs, call the physical model of particle multiple Coulomb scattering and energy loss to calculate the scattering physical offset within the medium of the energy conditioner sheet.

9. An electronic device, characterized in that, For simulating the transport process of particles in a target energy conditioner, the electronic device includes a memory and at least one processor. The memory stores a computer program, and the at least one processor is configured to perform the following steps when executing the computer program: Based on the structural parameters of the energy conditioner combination, construct an equivalent density model along the particle transport direction, and establish a supporting boundary information table. The boundary information table records at least the position information of the downstream boundary of each energy conditioner sheet in the energy conditioner combination, the equivalent water thickness accumulated from the incident end to this boundary, and the air gap length between this boundary and the upstream boundary of the next energy conditioner sheet; During the process of simulating the particle passing through the energy conditioner, through the current position of the particle and the boundary information table; judge the medium region where the current mean free path of the particle is located, and accordingly perform differential calculation on the offset generated by the particle movement in different regions until the particle completes the transport through the energy conditioner combination.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by at least one processor, it implements the steps of the method according to any one of claims 1-8 or the functions of the electronic device according to claim 9.

11. A computer program product, characterized in that, The computer program product includes a computer program, and when the computer program is executed by at least one processor, it implements the steps of the method according to any one of claims 1-8 or the functions of the electronic device according to claim 9.

12. A radiotherapy system, characterized in that, Includes: An apparatus for simulating particle transport, used to match simulated dose distribution information of particles with desired dose distribution information using the method for simulating particle transport as described in any one of claims 1-8; A device for determining human dose, used to determine the simulated dose as the dose used in radiotherapy after matching the simulated dose distribution information of the particles with the desired dose distribution information.

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