Monte Carlo dose calculation method and device based on kernel density estimation, equipment and medium

Abstract

The application provides a Monte Carlo dose calculation method and device based on kernel density estimation, equipment and medium, and relates to the technical field of dose calculation; the method comprises the following steps: establishing a corresponding transport model according to three-dimensional image data; establishing a virtual model according to the transport model, the virtual model comprising a plurality of second grids; determining the medium density ratio between each first grid and the corresponding second grid; determining the corresponding deposited energy of each first grid after the corresponding medium has a collision reaction according to the medium density ratio and the kernel density function; determining the target dose value of the radioactive particle according to each deposited energy and the mass of the corresponding medium of each first grid in each first grid; the kernel density estimation is combined with the virtual collision, so that a single collision of particles can contribute to the whole space dose distribution, the number of simulated particles is effectively reduced, the Monte Carlo dose calculation efficiency is improved, and the application of the Monte Carlo dose calculation method in the field of radiotherapy and the like is further promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dose calculation, in particular to a Monte Carlo dose calculation method based on kernel density estimation, device, equipment and medium. BACKGROUND

[0002] The Monte Carlo dose calculation method has high calculation precision and is the gold standard for dose calculation in radiotherapy; however, the slow calculation speed of the Monte Carlo calculation method limits its application in radiotherapy. SUMMARY

[0003] The purpose of the present application is to provide a Monte Carlo dose calculation method based on kernel density estimation, device, equipment and medium, in which the kernel density estimation is combined with virtual collision in the process of optoelectronic simulation, so that a single collision of particles can contribute to the full-space dose distribution, effectively reducing the number of simulated particles and improving the efficiency of Monte Carlo dose calculation, and further promoting the application of the Monte Carlo dose calculation method in the field of radiotherapy.

[0004] Embodiments of the present application are implemented as follows:

[0005] In a first aspect, the embodiments of the present application provide a Monte Carlo dose calculation method based on kernel density estimation, comprising the following steps:

[0006] Obtain three-dimensional image data of a lesion position of a patient, and establish a transport model corresponding to the three-dimensional image data according to the three-dimensional image data, wherein the transport model comprises a plurality of first grids, the plurality of first grids correspond to a human environment corresponding to the three-dimensional image data, and the transport model is used to simulate the transport process of radioactive particles in the human environment corresponding to the lesion position;

[0007] According to the transport model, a virtual model is established, the virtual model comprises a plurality of second grids, the plurality of second grids correspond to the human environment corresponding to the three-dimensional image data, and each second grid is filled with a set medium, and each first grid corresponds to a second grid;

[0008] According to the medium density of each first grid corresponding to each first grid and the medium density of each second grid in each second grid, the medium density ratio between each first grid and the corresponding second grid is determined;

[0009] According to each medium density ratio and a kernel density function, the corresponding deposited energy of the radioactive particles after the collision reaction with the medium corresponding to each first grid is determined, and for each first grid, the deposited energy represents the energy lost in the corresponding first grid after the collision reaction between the radioactive particles and the medium in the first grid;

[0010] According to each deposition energy and the mass of the medium corresponding to each of the first grids, a target dose value of the radiation particle is determined.

[0011] The beneficial effects of the present application are: by establishing a virtual model same as the transport model, and combining with the kernel density function, the radiation particle can be effectively diffused from one first grid to all the first grids in the transport model based on the calculation of the kernel density function; meanwhile, the kernel density function has a virtual collision reaction in the transport model, which solves the problem of difficult processing of the contour boundary in the kernel density estimation of the kernel density function, and after the contour boundary problem is processed, the number of simulation particles can be effectively reduced, and fast and accurate Monte Carlo dose calculation is realized.

[0012] Based on the above technical solutions, the present application can be further improved as follows.

[0013] Further, the deposition energy of the collision reaction between the radiation particle and the medium corresponding to each first grid is determined according to each medium density ratio and the kernel density function, wherein the deposition energy is expressed as:

[0014]

[0015] In the formula, i and j represent the number of the first grid, E represents the deposition energy, kernel(j, i) is the kernel density function, DensityRatioi represents the target density ratio of the corresponding grid, and ξ represents a random number between 0 and 1.

[0016] The beneficial effects of the above further scheme are: the deposition energy of the collision reaction between the radiation particle and the corresponding medium in each first grid is calculated through the kernel density function.

[0017] Further, the target dose value of each first grid is determined according to each deposition energy and the mass of the medium corresponding to each of the first grids, wherein the target dose value is expressed as:

[0018] D(i) = E(i) / mass(i);

[0019] In the formula, D(i) represents the target dose value of the i-th first grid, E(i) is the deposition energy corresponding to the i-th first grid, and mass(i) is the mass of the medium corresponding to the i-th first grid.

[0020] The beneficial effects of the above further scheme are: the target dose value corresponding to each first grid is determined through each deposition energy and the mass of the medium corresponding to each of the first grids.

[0021] In a second aspect, the embodiments of the present application provide a Monte Carlo dose calculation device based on kernel density estimation, which comprises:

[0022] a transport model module, configured to acquire three-dimensional image data of a lesion position of a patient, and establish a transport model corresponding to the three-dimensional image data according to the three-dimensional image data, the transport model comprising a plurality of first meshes, the plurality of first meshes corresponding to a human body environment corresponding to the three-dimensional image data, the transport model being used to simulate a transport process of a radioactive particle in the human body environment corresponding to the lesion position;

[0023] a virtual model module, configured to establish a virtual model according to the transport model, the virtual model comprising a plurality of second meshes, the plurality of second meshes corresponding to the human body environment corresponding to the three-dimensional image data, and each second mesh being filled with a set medium, and each first mesh corresponding to one second mesh;

[0024] a density ratio calculation module, configured to determine a medium density ratio between each first mesh and a corresponding second mesh according to a medium density corresponding to each first mesh in each first mesh and a medium density of each second mesh in each second mesh;

[0025] a deposition energy calculation module, configured to determine a corresponding deposition energy of the radioactive particle after a collision reaction with a medium corresponding to each first mesh according to each medium density ratio and a kernel density function, and for each first mesh, the deposition energy representing an energy lost in the corresponding first mesh after the collision reaction between the radioactive particle and the medium in the first mesh;

[0026] a dose calculation module, configured to determine a target dose value of the radioactive particle according to each deposition energy and a mass of the medium corresponding to each first mesh in each first mesh

[0027] Further, in the deposition energy calculation module, the deposition energy is expressed as:

[0028]

[0029] wherein i and j represent the number of the first mesh, E represents the deposition energy, kernel(j, i) is the kernel density function, DensityRatioi represents the target density ratio of the corresponding mesh, and ξ represents a random number between 0 and 1.

[0030] Further, in the dose calculation module, the target dose value is expressed as:

[0031] D(i)=E(i) / mass(i);

[0032] wherein D(i) represents the target dose value of the ith first mesh, E(i) is the deposition energy corresponding to the ith first mesh, and mass(i) is the mass of the medium corresponding to the ith first mesh.

[0033] In a third aspect, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the method of any one of the first aspect when executing the computer program.

[0034] In a fourth aspect, a non-transitory computer readable storage medium is provided, which stores computer instructions, and the computer instructions cause a computer to execute the method of any one of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0036] Figure 1 The method flow chart of the dose calculation method in the embodiments of the present application;

[0037] Figure 2 The connection schematic diagram of the dose calculation device in the embodiments of the present application;

[0038] Figure 3 The connection schematic diagram of the electronic device in the embodiments of the present application. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0041] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0042] EMBODIMENTS

[0043] In a first aspect, the embodiments of the present application provide a Monte Carlo dose calculation method based on kernel density estimation, comprising the following steps:

[0044] S1, obtaining three-dimensional image data of a lesion position of a patient, and establishing a transport model corresponding to the three-dimensional image data according to the three-dimensional image data, the transport model comprising a plurality of first grids, the plurality of first grids corresponding to a human body environment corresponding to the three-dimensional image data, the transport model being used to simulate a transport process of a radioactive particle in the human body environment corresponding to the lesion position;

[0045] The three-dimensional image data comprises CT data and delineation data. The CT value in the CT data is a measurement unit for measuring the density of a local tissue or organ in the human body. The CT value is usually referred to as a Hounsfield unit (HU), air is -1000, and dense bone is +1000. In fact, the CT value is a corresponding value of each tissue in the CT image and the X-ray attenuation coefficient. Both the matrix image and the matrix number represent the CT value, and the CT value is converted from the μ value of the human tissue and organ. The delineation data represents the size and contour information of a local tissue or organ in the human body.

[0046] Specifically, the transport model is used to simulate the transport process of the radioactive particle in the human body environment corresponding to the lesion position. The radioactive particle can be in the form of a neutron, a photon, an electron, a proton, an ion, or the like. The transport model is a model in the Monte Carlo method, also known as a statistical simulation method. The Monte Carlo method uses random numbers (or more commonly, pseudo-random numbers) to solve many computing problems. The transport model can also include a source model and a counting model. The source model is used to release the radioactive particle. The counting model is used to distinguish and count the first grid selected by the staff in the transport model. Generally, the first grid selected by the staff in the transport model is the first grid corresponding to the reaction of the radioactive particle and the deposition energy.

[0047] S2, establishing a virtual model according to the transport model, the virtual model comprising a plurality of second grids, the plurality of second grids corresponding to the human body environment corresponding to the three-dimensional image data, and each second grid being filled with a set medium, each first grid corresponding to a second grid;

[0048] The virtual model is established according to the transport model, is consistent in the shape contour, and is composed of a plurality of second grids. The number of the second grids in the virtual model is consistent with the number of the first grids in the transport model. The difference is that the virtual model is filled with a set medium, which can be a substance with a known density such as water.

[0049] S3, determining a medium density ratio between each first grid and a corresponding second grid according to the medium density corresponding to each first grid and the medium density of each second grid;

[0050] Wherein, the medium density corresponding to the first grid can be obtained when the transport model is established through the three-dimensional image data, because the CT value and the delineation data in the three-dimensional image data respectively represent the density of a certain local tissue or organ of the human body and the size and contour information of a certain local tissue or organ of the human body, so after the transport model is established, not only the medium density corresponding to the first grid can be obtained, but also the size of the first grid, the mass of the first grid, etc.

[0051] Specifically, by taking the medium density of the first grid as known and the medium in the second grid as a set medium, the medium density ratio between each first grid and the corresponding second grid can be calculated; for example, the medium density of the first grid is 2 grams per cubic centimeter, and the set medium in the second grid is water, so the medium density in the second grid is 1 gram per cubic centimeter, and thus the medium density ratio between the first grid and the corresponding second grid is 2.

[0052] S4, determining the corresponding deposited energy of the medium corresponding to each first grid after the collision reaction of the radioactive particles according to each medium density ratio and a kernel density function, and for each first grid, the deposited energy represents the energy lost in the corresponding first grid after the collision reaction of the radioactive particles with the medium in the first grid;

[0053] Wherein, by the medium density ratio between the first grid and the second grid, and according to the kernel density function, the corresponding deposited energy of the medium corresponding to each first grid after the collision reaction of the radioactive particles can be calculated.

[0054] Optionally, the above determining the corresponding deposited energy of the medium corresponding to each first grid after the collision reaction of the radioactive particles according to each medium density ratio and a kernel density function, wherein the deposited energy is expressed as:

[0055]

[0056] Wherein, i and j represent the number of the first grid, E represents the deposited energy, kernel(j, i) is the kernel density function, DensityRatioi represents the target density ratio of the corresponding grid, and ξ represents a random number between 0 and 1.

[0057] The kernel density function kernel(j, i) can be a Gaussian function, a Rectangular function, a Triangular function, a Biweight function, an Epanechnikov function, or an actual point kernel energy deposition function of a radioactive particle.

[0058] S5, determining a target dose value of the radioactive particle according to each deposition energy and a mass of the medium corresponding to each first grid in the plurality of first grids.

[0059] The target dose value of the radioactive particle corresponding to the corresponding first grid can be obtained by the mass of the medium in the corresponding first grid after obtaining the deposition energy of each first grid.

[0060] Optionally, the target dose value of the radioactive particle is determined according to each deposition energy and a mass of the medium corresponding to each first grid in the plurality of first grids, and the target dose value is represented as:

[0061] D(i) = E(i) / mass(i);

[0062] In the formula, D(i) represents the target dose value of the i-th first grid, E(i) represents the deposition energy corresponding to the i-th first grid, and mass(i) represents the mass of the medium corresponding to the i-th first grid.

[0063] After obtaining the target dose value corresponding to each first grid, the total dose value can be obtained according to the target dose values corresponding to the selected plurality of first grids by using a counting model.

[0064] In a second aspect, the embodiments of the present application provide a Monte Carlo dose calculation device based on kernel density estimation, comprising:

[0065] The transport model module is configured to obtain three-dimensional image data of a lesion position of a patient, and establish a transport model corresponding to the three-dimensional image data according to the three-dimensional image data. The transport model includes a plurality of first grids, and the plurality of first grids correspond to a human environment corresponding to the three-dimensional image data. The transport model is used to simulate a transport process of a radioactive particle in the human environment corresponding to the lesion position.

[0066] The virtual model module is configured to establish a virtual model according to the transport model. The virtual model includes a plurality of second grids, and the plurality of second grids correspond to the human environment corresponding to the three-dimensional image data. Each second grid is filled with a set medium, and each first grid corresponds to a second grid.

[0067] a density ratio calculation module configured to determine a medium density ratio between each first grid and a corresponding second grid according to a medium density corresponding to each first grid and a medium density of each second grid;

[0068] a deposition energy calculation module configured to determine a corresponding deposition energy of a radioactive particle after a collision reaction with a medium corresponding to each first grid according to each medium density ratio and a kernel density function, wherein the deposition energy represents an energy lost in the corresponding first grid after the collision reaction between the radioactive particle and the medium in the first grid;

[0069] a dose calculation module configured to determine a target dose value of the radioactive particle according to each deposition energy and a mass of the medium corresponding to each first grid

[0070] Further, in the deposition energy calculation module, the deposition energy is expressed as:

[0071]

[0072] wherein i and j represent the number of the first grid, E represents the deposition energy, kernel(j, i) is the kernel density function, DensityRatioi represents the target density ratio of the corresponding grid, and ξ represents a random number between 0 and 1.

[0073] Further, in the dose calculation module, the target dose value is expressed as:

[0074] D(i) = E(i) / mass(i);

[0075] wherein D(i) represents the target dose value of the ith first grid, E(i) is the deposition energy corresponding to the ith first grid, and mass(i) is the mass of the medium corresponding to the ith first grid.

[0076] In a third aspect, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method of any one of the first aspect when executing the computer program.

[0077] In a fourth aspect, a non-transitory computer readable storage medium is provided, which stores computer instructions, and the computer instructions cause a computer to execute the method of any one of the first aspect.

[0078] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics thereof. The embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference herein to any prior art is to be taken as an admission that the application is not entitled to antedate such prior art by virtue of prior application. Any reference to the use of a term in the singular herein shall also be taken to refer to the plural, and vice versa, unless otherwise indicated by context. Any reference to the use of a term in the present application shall be taken to refer to the use of the term in the context of the present application, and not to the use of the term in any other context. Any reference to the use of a term in the present application shall be taken to refer to the use of the term in the context of the present application, and not to the use of the term in any other context.

Claims

1. A Monte Carlo dose calculation method based on kernel density estimation, characterized in that, Includes the following steps: Three-dimensional image data of the lesion location of the patient is acquired, and a transport model corresponding to the three-dimensional image data is established based on the three-dimensional image data. The transport model includes multiple first grids, and the multiple first grids correspond to the human body environment corresponding to the three-dimensional image data. The transport model is used to simulate the transport process of radioactive particles in the human body environment corresponding to the lesion location. Based on the transport model, a virtual model is established. The virtual model includes multiple second grids, each of which corresponds to the human body environment corresponding to the three-dimensional image data. The medium filled by each second grid is a set medium, and each first grid corresponds to one second grid. Based on the medium density corresponding to each first grid in each first grid and the medium density of each second grid in each second grid, determine the medium density ratio between each first grid and the corresponding second grid; Based on the density ratio of each medium and the nuclear density function, the deposition energy corresponding to the radioactive particle after colliding with the medium corresponding to each first grid during transport calculation is determined. For each first grid, the deposition energy characterizes the energy lost in the corresponding first grid after the radioactive particle collides with the medium in the first grid. The target dose value of the radioactive particles is determined based on the deposition energy and the mass of the medium corresponding to each of the first grids in each of the first grids.

2. The Monte Carlo dose calculation method based on kernel density estimation according to claim 1, characterized in that, The deposition energy is determined based on the density ratio of each medium and the nuclear density function, after the radioactive particle collides with the medium corresponding to each of the first grids. The deposition energy is expressed as: In the formula, i and j represent the numbers of the first grid, E represents the deposition energy, kernel(j,i) is the kernel density function, DensityRatio(i) represents the target density ratio of the corresponding grid, and ξ represents a randomly selected random number between 0 and 1.

3. The Monte Carlo dose calculation method based on kernel density estimation according to claim 2, characterized in that, The target dose value of the radioactive particles is determined based on the deposition energy and the mass of the medium corresponding to each of the first grids, wherein the target dose value is expressed as: D(i) = E(i) / mass(i); In the formula, D(i) represents the target dose value of the i-th first grid, E(i) is the deposition energy corresponding to the i-th first grid, and mass(i) is the mass of the medium corresponding to the i-th first grid.

4. A Monte Carlo dose calculation device based on kernel density estimation, characterized in that, include: The transport model module is used to acquire three-dimensional image data of the lesion location of the patient, and to establish a transport model corresponding to the three-dimensional image data. The transport model includes multiple first grids, and the multiple first grids correspond to the human body environment corresponding to the three-dimensional image data. The transport model is used to simulate the transport process of radioactive particles in the human body environment corresponding to the lesion location. The virtual model module is used to establish a virtual model based on the transport model. The virtual model includes multiple second grids, each of which corresponds to the human body environment corresponding to the three-dimensional image data. The medium filled by each second grid is a set medium, and each first grid corresponds to one second grid. The density ratio calculation module is used to determine the medium density ratio between each first grid and its corresponding second grid based on the medium density of each first grid and the medium density of each second grid. The deposition energy calculation module is used to determine the deposition energy corresponding to the radioactive particle after it collides with the medium corresponding to each first grid during transport calculation, based on the density ratio of each medium and the kernel density function. For each first grid, the deposition energy represents the energy lost in the corresponding first grid after the radioactive particle collides with the medium in the first grid. The dose calculation module is used to determine the target dose value of the radioactive particles based on the deposition energy and the mass of the medium corresponding to each of the first grids in each of the first grids.

5. The Monte Carlo dose calculation device based on kernel density estimation according to claim 4, characterized in that, In the deposition energy calculation module, the deposition energy is represented as: In the formula, i and j represent the numbers of the first grid, E represents the deposition energy, kernel(j,i) is the kernel density function, DensityRatio(i) represents the target density ratio of the corresponding grid, and ξ represents a randomly selected random number between 0 and 1.

6. The Monte Carlo dose calculation device based on kernel density estimation according to claim 4, characterized in that, In the dose calculation module, the target dose value is represented as: D(i) = E(i) / mass(i); In the formula, D(i) represents the target dose value of the i-th first grid, E(i) is the deposition energy corresponding to the i-th first grid, and mass(i) is the mass of the medium corresponding to the i-th first grid.

7. An electronic device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method of any one of claims 1-3.

8. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to perform the method of any one of claims 1-3.

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