Radiation irradiation system and control method therefor

Abstract

To provide a radiation irradiation system and a control method therefor.SOLUTION: A radiation irradiation system and a control method therefor are provided. On the basis of weight proportions of elements in a human body and reaction intensities of the elements with a neutron and a photon, the element that has influence on simulation calculation results of the neutron and the photon in an application scenario of the radiation irradiation system is screened out, and during a simulation process, only the screened-out element is simulated, so that the calculation speed can be greatly improved, and the calculation time can be reduced.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] One aspect of the present invention relates to an irradiation system, and another aspect of the present invention relates to an irradiation system This invention relates to a method for controlling a system. [Background technology]

[0002] With the development of atomic science, radiation therapy such as cobalt-60, linear accelerator, and electron beam , which has already become one of the main means of cancer treatment. However, conventional photon or electron therapy, The physical conditions of the radiation itself are limited to kill tumor cells, and many of the beam paths Damage to normal tissues. Also, tumor cells have different degrees of sensitivity to radiation. Conventional radiation therapy is not effective against malignant tumors with high radiation resistance (e.g., glioblastoma multiforme (GLIP)). oblastoma multiforme, melanoma The treatment is not very effective.

[0003] Chemotherapy is used to reduce radiation damage to the normal tissue surrounding the tumor. The concept of targeted therapy in radiation therapy has been applied to radiation therapy. Currently, there are many treatments for highly aggressive tumor cells, such as proton therapy, heavy particle therapy, and neutron capture therapy. relative biological effectiveness Radiation sources with high radiation yield (RBE) are being actively developed. The combination of the above two concepts is used, for example in boron neutron capture therapy (BOC). In Neutron Capture Therapy (BNCT), boron-containing drugs are used By specifically collecting on tumor cells and combining this with highly precise beam control, providing better cancer treatment options.

[0004] Boron neutron capture therapy is a method to 10 B) The drug contains a large capture cutoff for thermal neutrons. Taking advantage of the surface area, 10B(n,α)7Li neutron capture and nuclear fission reactions , 4 He and 7 The total range of the two particles is about one micrometer. The size of the boron-containing The drug selectively collects in tumor cells and, when combined with an appropriate neutron beam source, is then delivered to normal tissue. It can achieve the goal of partially killing tumor cells without causing major damage. do.

[0005] The emitted particles are then sent to the brain to kill as many cancer cells as possible while minimizing damage to healthy cells. To achieve this, CT or PET imaging is usually performed before treating the patient, and the decision is made based on the imaging results. The tissue material information of the human body is obtained, and a calculation model is established based on the material information and the radiation source. , simulating the transport process of radioactive particles in the human body, and finally, the dose of radioactive particles in the human body The distribution is obtained, and the optimal plan of the dose distribution for the patient is selected as the treatment scheme for the patient. Select.

[0006] Currently, the dose calculation module in radiation therapy planning systems mainly uses the Monte Carlo method. The results were obtained by simulating the emitted particles in a conventional radiation therapy. In contrast, radiation therapy requires simulation of the motion process of electrons and It is necessary to simulate the motion process of electrons and photons. Currently, the Monte Carlo method is Although it is the most accurate method of dose calculation, the calculations are time consuming and memory intensive.

[0007] Currently, general-purpose Monte Carlo programs such as MCNP and Geant4 are used for radiation therapy calculations. The MCNP program is often used for nuclear reactor design calculations. ant4 was first used for high energy physics calculations and was used in the early stages of design for the physics sequence of radiation therapy. No special optimizations are made to the radiation treatment calculations because the radiation treatment Planning usually needs to be completed within a certain time frame. For example, radiation therapy The radiation therapy planning system is required to be able to create a treatment scheme within an hour, and the dosimeter The calculation process takes up the majority of the time required to create a radiation therapy plan. Dose calculation methods need to be optimized to reduce Summary of the Invention

[0008] In order to overcome the deficiencies of the prior art, the radiation irradiation system according to the first aspect of the present invention provides A beam for forming an irradiated area by generating a therapeutic beam and irradiating the irradiated area with the therapeutic beam. The irradiation device and the dose are calculated based on the parameters of the treatment beam and the medical image data of the irradiated area. Perform simulation calculations and create treatment plans to determine the weight ratio and concentration of elements in the human body. In terms of the application of radiation irradiation systems, the strength of the reaction with neutrons and photons is taken into account. Screening elements that have an influence on the results of the electron and photon simulation calculations During the simulation process, only the screened elements are simulated. The treatment planning module controls the irradiation of the beam irradiation device based on the treatment plan. and

[0009] In another embodiment, the elements screened by the treatment planning module are H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar , K and Ca.

[0010] More specifically, the elements screened by the treatment planning module are H, He , Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca.

[0011] In another embodiment, the treatment planning module includes a corresponding neutron cross section database for each element. Remove all databases from the database that correspond to temperatures other than 294 K and 0 K.

[0012] The radiation delivery system is preferably a neutron capture therapy system, and the beam delivery device The neutron generator includes a neutron generator, a beam shaper, and a treatment table. The neutron generator includes an accelerator and a The accelerator accelerates the charged particles to generate a charged particle beam, and the target The beam shaper reacts with the neutrons generated by the neutron generator to generate a neutron beam. The neutron beam generated by the neutron generator can be adjusted to a desired beam quality. The light passes through the beam shaping body and is irradiated onto the subject on the treatment table.

[0013] In a method for controlling a radiation irradiation system according to a second aspect of the present invention, generates a treatment beam and irradiates the treatment beam onto an irradiated body to form an irradiated area. A beam irradiation device and a method for determining the parameters of a therapeutic beam and the medical image data of an irradiated area. A treatment planning module performs dose simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on the treatment plan, The control method of the radiation system is based on the weight ratio of the element in the human body and the reaction strength with neutrons and photons. Taking all of these factors into consideration, we have developed a simulation system for neutrons and photons in the application of radiation irradiation systems. Screening elements that have an influence on the calculation results and The method includes a step of simulating only the screened elements.

[0014] In another embodiment, the elements screened by the treatment planning module are H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar , K and Ca.

[0015] More specifically, the elements screened by the treatment planning module are H, He , Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca.

[0016] In another embodiment, the control method further comprises the treatment planning module determining a corresponding neutron isotopic fraction for each element. Remove the data corresponding to temperatures other than 294K and 0K from the area database. The method further includes the steps of:

[0017] The radiation delivery system is preferably a neutron capture therapy system, and the beam delivery device The neutron generator includes a neutron generator, a beam shaper, and a treatment table. The neutron generator includes an accelerator and a The accelerator accelerates the charged particles to generate a charged particle beam, and the target The beam shaper reacts with the neutrons generated by the neutron generator to generate a neutron beam. The neutron beam generated by the neutron generator can be adjusted to a desired beam quality. The light passes through the beam shaping body and is irradiated onto the subject on the treatment table.

[0018] The radiation irradiation system and the control method thereof according to the embodiment of the present invention are The ratio and the reaction strength with neutrons and photons are combined to determine the application scenario of the radiation irradiation system. In this study, we screened elements that have an influence on the results of neutron and photon simulation calculations. During the simulation process, only the screened elements are simulated. By combining the two, the calculation speed of the treatment planning module has been significantly improved, reducing calculation time. can be reduced.

[0019] A radiation irradiation system according to a third aspect of the present invention generates a therapeutic beam and A beam irradiation device for irradiating a therapeutic beam to an irradiated body to form an irradiated part, A dose simulation is performed based on the parameters of the beam and the medical image data of the irradiated area. A treatment planning module that performs calculations and creates a treatment plan, the treatment planning module including: Assigning simulation tasks to different processes or threads and running each process or thread The treatment planning module collects all the calculation tasks of the treatment plan and then obtains the final calculation results. a control module for controlling irradiation of the beam irradiation device based on the treatment plan; , including.

[0020] The radiation delivery system is preferably a neutron capture therapy system, The apparatus includes a neutron generator, a beam shaper, and a treatment table, the neutron generator being an accelerating The accelerator accelerates the charged particles to generate a charged particle beam, and and the beam shaper interacts with the target to generate a neutron beam. The neutron generator is capable of adjusting the neutron beam generated by the device to a predetermined beam quality. The neutron beam generated by the neutron ray passes through the beam shaping body and reaches the subject on the treatment table. It is irradiated.

[0021] In one embodiment, particles are processed by CPU process parallelism, thread parallelism, and GPU acceleration. Simulation was performed using multi-core CPUs for both process parallelism and thread parallelism. The process of CPU process parallelism and thread parallelism is as follows: A step in which the system obtains the number of processes or threads to obtain a value n; The system divides the particles to be simulated into n uniform parts, and each thread Or, one particle is simulated independently in each process and counted. and finally, the system performs a process or a thread-based computation of the counts obtained in each process or thread. and calculating the number of counts to obtain a final dose.

[0022] In one embodiment, the GPU acceleration is performed by parallel computation of the multi-core processor of the GPU. The process of GPU-accelerated simulation calculation is as follows: first, the system generates random numbers, cross sections, The product data is transferred from the CPU memory to the GPU graphic memory, and then Each processor simulates, calculates, counts, and computes a single particle. and calculating a global count based on the results of the simulation. Determine whether there are any unsimulated particles, and if there are no unsimulated particles The counting results are transferred from the GPU memory to the CPU memory, and the unsimulated If there are any particles that have not been simulated, go back to the previous step and repeat the simulation until all particles have been simulated. , the step of continuing to simulate and count the unsimulated particles. Including,

[0023] In a method for controlling a radiation irradiation system according to a fourth aspect of the present invention, The system generates a therapeutic beam and irradiates the subject with the therapeutic beam to treat the subject. and a beam irradiation device for forming a therapeutic beam and a medical image of the irradiated area. A treatment plan is created by performing dose simulation calculations based on image data. a control module for controlling irradiation of the beam irradiation device based on the treatment plan. and a simulation program for simulating different source particles. Assign application tasks to different processes or threads and run the computations of each process or thread. It includes a step of consolidating the tasks after they are completed to obtain a final calculated result.

[0024] In one embodiment, particles are processed by CPU process parallelism, thread parallelism, and GPU acceleration. Simulate.

[0025] Preferably, both process parallelism and thread parallelism are performed using a multi-core CPU. Realize parallel computing.

[0026] In one embodiment, the process parallel and thread parallel calculation process of the CPU first The system obtains the number of processes or threads to obtain a value n; and then the system The system divides the particles to be simulated into n uniform parts, and then In each step, one particle is simulated independently, and the and finally, the system is and calculating the count number to obtain the final dose.

[0027] Preferably, the GPU acceleration is achieved by parallel computation of a multi-core processor of the GPU. do.

[0028] The process of GPU-accelerated simulation calculation begins with the system generating random numbers, cross-section data, and The data is transferred from the CPU memory to the GPU graphic memory, and then each process in the GPU is The processor simulates, calculates, and counts single particles, and then graphs the counting results. and calculating the global counts, and the system is simulated. If there are no particles that have not been simulated, The simulation results are transferred from the GPU memory to the CPU memory, and the unsimulated particles are If there are any, go back to the previous step and retry the simulation until all particles are simulated. continuing to simulate and count the unsimulated particles; include.

[0029] The radiation irradiation system and the control method thereof according to the embodiment of the present invention are Assigning the simulation tasks to different processes or threads and each process or thread After completing each calculation task, they are summarized to obtain the final calculation result. It can significantly improve speed and reduce computation time.

[0030] A radiation irradiation system according to a fifth aspect of the present invention generates a therapeutic beam and A beam irradiation device for irradiating a therapeutic beam to an object to be irradiated to form an irradiated area and the therapeutic beam A dose simulation calculator is used based on the parameters of the system and the medical image data of the irradiated area. A treatment planning module that performs calculations and creates a treatment plan, the photon half absorption thickness being a first 1. Treatment planning module that stops simulation for photons if the value is less than a predefined value a control module for controlling irradiation of the beam irradiation device based on the treatment plan; Includes.

[0031] The radiation delivery system is preferably a neutron capture therapy system, The apparatus includes a neutron generator, a beam shaper, and a treatment table, the neutron generator being an accelerating The accelerator accelerates the charged particles to generate a charged particle beam, and and the beam shaper interacts with the target to generate a neutron beam. The neutron generator is capable of adjusting the neutron beam generated by the device to a predetermined beam quality. The neutron beam generated by the neutron ray passes through the beam shaping body and reaches the subject on the treatment table. It is irradiated.

[0032] In one embodiment, the treatment planning module calculates the half-absorption thickness t of the photon beam in accordance with equation (1-1): Calculate,

number

[0033] The first predetermined value is the size of a single cell, and preferably the first predetermined value is 0.2 m m, and if the photon energy is less than or equal to the second predetermined value, The half absorption thickness of the electron is less than or equal to a first predetermined value, and the second predetermined value is 10 KeV.

[0034] A method for controlling a radiation irradiation system according to a sixth aspect of the present invention, comprising: The system generates a therapeutic beam and irradiates the subject with the therapeutic beam to treat the subject. and a beam irradiation device for forming a therapeutic beam and a medical image of the irradiated area. A treatment plan is created by performing dose simulation calculations based on image data. a control module for controlling irradiation of the beam irradiation device based on the treatment plan. and a control unit for controlling the radiation irradiation system, the control unit comprising: If it is less than or equal to the value, stopping the simulation for the photon.

[0035] In one embodiment, the treatment planning module calculates the half-absorption thickness t of the photon beam in accordance with equation (1-1): Calculate,

number

[0036] The first predetermined value is the size of a single cell.

[0037] Preferably, the first predetermined value is 0.2 mm.

[0038] If the photon energy is equal to or less than a second predetermined value, the half-absorption of the photon corresponding to the photon energy is The thickness is less than or equal to a first predetermined value.

[0039] Preferably, the second predetermined value is 10 KeV.

[0040] The radiation irradiation system and the control method thereof according to the embodiment of the present invention are 1 If the value is less than or equal to a given value, the simulation for the photon is stopped, and the calculation On the premise of ensuring accuracy, the calculation time can be reduced.

[0041] A radiation irradiation system according to a seventh aspect of the present invention generates a therapeutic beam and A beam irradiation device that irradiates the target body with radiation to form the irradiated area and the parameters of the treatment beam Dose simulation calculations are performed based on the data and medical image data of the irradiated area, and A treatment planning module that creates a treatment plan by simulating particles using variance reduction. A treatment planning module for determining the treatment plan and a control module for controlling the irradiation of the beam irradiation device based on the treatment plan. Joules and.

[0042] In addition, variance reduction can be achieved by using implicit absorption, weight window games, and Russian roulette. and splitting, and the radiation delivery system is a neutron capture therapy system. The beam irradiation device includes a neutron generator, a beam shaper, and a treatment table. The present invention includes an accelerator and a target, and the accelerator accelerates charged particles to generate a charged particle beam. The beam shaper is a neutron generator that generates a neutron beam by interacting with the target. The neutron beam generated by the neutron generator can be adjusted to a desired beam quality. The neutron beam passes through a beam shaper and is irradiated onto the subject placed on the treatment table.

[0043] In a method for controlling a radiation irradiation system according to an eighth aspect of the present invention, generates a treatment beam and irradiates the treatment beam onto an irradiated body to form an irradiated area. A beam irradiation device and a method for determining the parameters of a therapeutic beam and the medical image data of an irradiated area. A treatment planning module performs dose simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on the treatment plan, The control method of the irradiance system is that the treatment planning module simulates particles by variance reduction. The method includes the step of:

[0044] In addition, variance reduction can be achieved by using implicit absorption, weight window games, and Russian roulette. and splitting, the step of simulating the particles by variance reduction comprising: Step S1 acquires one source particle, and determines whether the particle collides within a grid cell. If it is determined that a collision will occur, steps S3 and S4 are executed in sequence. If it is determined that a collision will not occur, Step S2 in which steps S5 and S6 are executed in sequence, and step S3 in which an implicit absorption process is executed S3 and determine whether the weight is lower than the weight window. If it is lower, If it is determined that the temperature is not low, the process returns to step S2. Step S5 for performing cyan roulette and splitting processing; and Russian roulette It is determined whether or not to perform the process. If it is determined that the Russian roulette process is to be performed, step S 7, and if it is determined that the Russian roulette process is not to be performed, the process returns to step S2. Step S6: Determine whether to erase the object. If it is determined that the object should be erased, step S8: If it is determined not to erase the data, step S9 is executed and then the process returns to step S2. Step S7: Determine whether the processing of the particles is completed. If it is determined that the processing is completed, If the flow is terminated and it is determined that the process is not completed, the process returns to step S1, step S8, and the process continues. and step S9 of dividing the probability by the extinction probability.

[0045] Furthermore, Russian roulette and splitting are based on the lattice space importance of each lattice. Step S1 of calculating and recording the particle size, step S2 of acquiring the particle, and Step S3 detects and operates the weight window before and after the particle crosses the lattice boundary. Lattice Space Importance I n and I n+1 Step S4 of calculating I n I n+1 Yo If it is not greater, step S6 is executed and then step S3 is executed. Return to step S5 and split the particle if it is larger. Step S6: determining whether to annihilate the particle and reduce the particle weight; If it is determined that the child should be annihilated, step S9 is executed. If so, return to step S3 after executing step S8, and set the particle weight to step S7. Step S8 to increase the number of particles, and to determine whether the simulation of the particles is completed. If it is determined that the simulation is not complete, the process returns to step S2. If it is determined that the process is completed, the process ends at step S9.

[0046] Furthermore, implicit absorption is performed by acquiring particles in step S1 and determining whether the particles collide within a lattice cell. If it is determined that a collision will occur, step S3 is executed. If it is determined that a collision will not occur, step S4 is executed. If so, return to step S1, step S2, and step S3 of multiplying the weight by the probability of scattering occurrence. Then, determine whether the particle's weight is smaller than the lowest weight. If it is smaller, Step S5 is executed, and if it is determined that the difference is not smaller, the process returns to step S2. Step S4 and It is determined whether or not to annihilate the particle, and if it is determined that the particle is to be annihilated, step S7 is performed. If it is determined that the particle is not to be annihilated, step S6 is executed and then step S2 is executed. Return to step S5, step S6 of dividing the weight by the annihilation probability, and the simulation of the particle If it is determined that the simulation is not complete, the step Step S1 is returned to, and if it is determined that the simulation is completed, step S7 is terminated; Includes.

[0047] Furthermore, the weight window game includes a step S1 of simulating particle motion. Then, determine whether the particle weight is within the weight window range and determine whether it is within the range. If so, return to step S1; if not, execute step S3 Step S2: Determine whether the weight is greater than the weight window. If it is determined that the weight is greater than the weight window, If so, the process returns to step S1 after executing step S4; if it is determined that the difference is not greater, Step S3 performing step S5, splitting particles and lowering weights Step S4: Determine whether to erase the object. If it is determined that the object should be erased, the process ends. If it is determined that the user should not be allowed to enter the password, the process returns to step S1 after executing step S6. 5 and step S6 of increasing the weights of the particles.

[0048] In one embodiment, the lattice spatial importance is calculated by solving the adjoint transport equation: It is acquired,

number

[0049] More specifically, the particles have a lattice space importance I n Import lattice space from lattice The chest is I n+1 The motion is performed on the grid of I n+1 >I n If so, m = I n+1 / I n west, Split the particle into m particles and reduce the weight of each particle to 1 / m of the original weight. I n+1 n If so, we can play Russian roulette on the particles and get P=I n+1 / I n Then, sample a random number x between 0 and 1. If x is smaller than P, a particle is generated. If it remains, multiply the weight by 1 / P. Otherwise, the particle is annihilated and the particle simulation is Exit the program.

[0050] In another embodiment, the particle weight has an upper limit of 10 and a lower limit of 0.25. If w is greater than 10, the integer part of w is set to w1, the decimal part to w2, and the Sample a random number x. If x is less than w2, set w=w1+1, and if x is greater than w2, If it is greater than w, let w = w1, then split one particle into w particles. ​,The simulation is run until the weight of each particle drops to 1.

[0051] The radiation irradiation system and the control method thereof according to the embodiment of the present invention are By performing simulation, it is possible to reduce the calculation time while ensuring the accuracy of the calculation. This can be done.

[0052] A radiation irradiation system according to a ninth aspect of the present invention is a system for generating a therapeutic beam, The beam irradiation device irradiates the target body with a beam to form an irradiated area, and the parameters of the treatment beam are set A dose simulation calculation is performed based on the data and medical image data of the irradiated area, and A treatment planning module that creates a treatment plan using a non-uniform grid for simulation. The treatment planning module performs the calculation of the beam and controls the irradiation of the beam irradiation device based on the treatment plan. and a control module for controlling the operation of the control unit.

[0053] In addition, the treatment planning module may set the grid size of the critical regions to be smaller than the grid size of the non-critical regions. Set it small.

[0054] In addition, the treatment planning module can reduce the grid size of the tumor area to less than 0.4 mm. Set it up.

[0055] In addition, the treatment planning module scales the grid dimensions of the blood, air, and bone regions to 1.6 Set it to mm or more.

[0056] In addition, the treatment planning module reduces the size of the grid of the area where normal muscle is located to 0.8 mm. Set it larger than 1.6mm and smaller than 1.

[0057] The radiation delivery system is preferably a neutron capture therapy system, and the beam delivery device The neutron generator includes a neutron generator, a beam shaper, and a treatment table. The neutron generator includes an accelerator and a The accelerator accelerates the charged particles to generate a charged particle beam, and the target The beam shaper reacts with the neutrons generated by the neutron generator to generate a neutron beam. The neutron beam generated by the neutron generator can be adjusted to a desired beam quality. The light passes through the beam shaping body and is irradiated onto the subject on the treatment table.

[0058] In a method for controlling a radiation irradiation system according to a tenth aspect of the present invention, The system generates a therapeutic beam and irradiates the therapeutic beam onto a target body to form an irradiated area. The beam irradiation device controls the parameters of the therapeutic beam and the medical image data of the irradiated area. a treatment planning module for performing dose simulation calculations and creating a treatment plan; a control module for controlling irradiation of the beam irradiation device based on the treatment plan; The control method of the irradiation system is that the treatment planning module uses a non-uniform grid for simulation. The method includes a step of performing a calculation.

[0059] The control method includes a treatment planning module that calculates the grid size of the important region by the grid size of the non-important region. The method further includes the step of setting the value smaller than the value specified by the first embodiment.

[0060] The control method includes a treatment planning module that adjusts the size of the grid of the area where the tumor is located to 0.4 mm or less. The method further includes the step of:

[0061] The control method includes a treatment planning module that determines the size of a grid of regions where blood, air, and bone are present. The size of the grid in the area where normal muscle is located is set to 1.6 mm or more, and the size of the grid in the area where normal muscle is located is set to 0.8 mm or more. The method further includes the step of setting the distance to less than 1.6 mm.

[0062] The radiation irradiation system and the control method thereof according to the embodiment of the present invention use a non-uniform grid. By performing simulation calculations, it is possible to identify important areas without significantly increasing the calculation time. Improve the calculation accuracy of the critical area, meet the calculation accuracy of non-critical areas, and reduce the calculation time. It can be done. [Brief description of the drawings]

[0063] [Figure 1] FIG. 1 is a schematic diagram of a module of a boron neutron capture therapy system according to an embodiment of the present invention. [Diagram 2] 1 is a schematic diagram of a boron neutron capture therapy system according to an embodiment of the present invention. [Diagram 3] 1 is a flowchart of process parallelism and thread parallelism of a CPU in an embodiment of the present invention. [Figure 4] 1 is a flowchart of a simulation calculation using a GPU in an embodiment of the present invention. [Diagram 5] 1 is a flowchart for simulating particles using a variance reduction method in an embodiment of the present invention. [Figure 6] 1 is a flowchart of Russian roulette and splitting in an embodiment of the present invention. [Figure 7] 1 is a flowchart of implicit absorption in an embodiment of the present invention. [Figure 8] 1 is a flowchart of a wait window game in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] The present invention will now be described in more detail with reference to the accompanying drawings, which will enable those skilled in the art to If so, the invention can be implemented by reference to the text of the specification.

[0065] Neutron capture therapy has been increasingly applied in recent years as an effective means of cancer treatment. Of these, boron neutron capture therapy has become the most common. The neutrons used for can be provided by a nuclear reactor or an accelerator. Capture therapy (Boron Neutron Capture Therapy, BNCT) is boron ( 10 B) The drug has a large capture cross section for thermal neutrons. Utilizing 10 B(n,α) 7 Li neutron capture and fission reactions 4 He and 7 Li and The two heavy charged particles have an average energy of about 2.33 MeV. V and high linear energy transfer (L The linear energy and range of the alpha particles are 150 KeV / μm, 8μm 7 For Li heavy charged particles, 175 KeV / μm 5 μm, and the total range of the two types of particles is equivalent to the size of one cell, so Radiation damage is limited to the cellular level. Boron-containing drugs are selectively concentrated in tumor cells and By combining it with an appropriate neutron beam source, tumor cells can be targeted without causing significant damage to normal tissue. This can achieve the purpose of precisely killing the cells.

[0066] The neutron source for boron neutron capture therapy is a nuclear reactor or a nuclear reaction between a charged particle and a target. Regardless of the source, all produce a mixed radiation field, i.e. the beam is Boron neutron capture therapy for deep tumors, including neutrons and photons from low to high energy Regarding the amount of radiation, except for epithermal neutrons, the higher the content of other radiation, the greater the risk of injury in normal tissue. The proportion of selective dose depositions is also increased, so the proportion of these unnecessary dose depositions is also increased. In addition to the quality of the air beam, the radiation caused by neutrons must be reduced as much as possible. To further understand dose distribution in the human body, embodiments of the present invention provide a method for measuring dose distribution in human head tissue. The dose distribution was calculated using the prosthesis and the beam quality factors in the prosthesis were then considered. This will serve as a reference for neutron beam design.

[0067] The International Atomic Energy Agency (IAEA) has approved a neutron source for use in clinical boron neutron capture therapy. The five proposals for air beam quality elements were made based on different neutron sources. It can be used to compare the advantages and disadvantages of the neutron generation path and the beam shaper. These can be used as a reference when designing. The five proposals are as follows:

[0068] Epithermal neutron flux>1x10 9 n / cm 2 s Fast neutron contamination<2×10 - 13 Gy-cm 2 / n Photon contamination<2×10 -13 Gy-cm 2 / n Ratio of thermal to epithermal neutron flux tron flux ratio<0.05 Epithermal neutron current to flux ratio>0.7 Note: The epithermal neutron energy range is 0.5 eV to 40 KeV, and the thermal neutron energy range is -region is less than 0.5 eV, and fast neutron energy region is greater than 40 KeV .

[0069] As shown in FIG. 1, the radiation irradiation system in this embodiment is a boron neutron capture therapy system. The system includes a neutron beam irradiation device, a treatment planning module, and a control module. The neutron beam irradiation device 10 generates a therapeutic neutron beam N and The therapeutic neutron beam N is irradiated to the subject 200 to form an irradiated area. The neutron beam irradiation device 10 generates a therapeutic neutron beam N. The neutron beam irradiation device 10 controls the parameters of the therapeutic neutron beam N. Dose simulation calculations are performed based on the data and medical image data of the irradiated area, and A treatment plan is created, and the exposure to the neutron beam irradiation device 10 during irradiation treatment is determined based on the treatment plan. The position of the irradiation site and the corresponding irradiation time are determined. After positioning the subject 200, treatment can begin and the control module 30 Retrieving a treatment plan corresponding to the current patient from the treatment plan module; and The control module 30 controls the irradiation of the neutron beam irradiation device 10 based on the treatment plan. , other data information, for example, data of the neutron beam irradiation device 10, data of the irradiation target 200 The device may also receive data, etc.

[0070] As shown in FIG. 2, in this embodiment, the neutron beam irradiation device 10 is a neutron generator. 11, a beam shaper 12, a collimator 13 and a treatment table 14. The neutron generator 11 The accelerator 111 includes a target T, and the accelerator 111 is configured to irradiate charged particles (e.g., protons, deuterium oxide, etc.). The charged particle beam P is generated by accelerating charged particles (e.g., deuterium nuclei) and generating a proton-like charged particle beam P. The ray P is irradiated to the target T and interacts with the target T to produce a neutron ray (neutron beam). N is generated, and the target T is preferably a metal target. and energy, the energy and current of the accelerated charged particles that can be provided, and the metal target Appropriate nuclear reactions are selected and generally studied based on the physical and chemical properties of the The nuclear reaction is 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B and these two The reactions of the two species are endothermic. The energy thresholds of the two nuclear reactions are 1.881MeV and 2.055MeV, making them ideal neutron sources for boron neutron capture therapy are epithermal neutrons with keV energy levels, so theoretically, By bombarding a metallic lithium target with slightly higher protons, a relatively low energy can be produced and used clinically without requiring significant slowing down. However, two types of targets, metallic lithium (Li) and metallic beryllium (Be), are available. does not have a high cross section for interacting with threshold energy protons and generates a sufficiently large neutron flux To achieve this, protons with relatively high energy are generally selected to induce nuclear reactions. An ideal target would have a high neutron yield and the energy distribution of the generated neutrons would be similar to that of the epithermal target. There are many radiations with strong penetrating properties close to the neutron energy region (described in detail below). It is safe, inexpensive, easy to operate, and has high temperature resistance, but In practice, it is impossible to find a nuclear reaction that satisfies all the requirements, and in the embodiments of the present invention In the present invention, targets made of lithium metal are used. As is known to those skilled in the art, The battery T may be made of metal materials other than lithium and beryllium, for example tantalum. The target T may be formed of, for example, tungsten (W) or tungsten (Ta). The accelerator 11 may be of any other solid form, or may be a liquid material (liquid metal). 1 is a linear accelerator, cyclotron, synchrotron, synchrocyclotron Alternatively, the neutron generator 11 may be a nuclear reactor without using an accelerator and a target. The neutron source for boron neutron capture therapy is a nuclear reactor or accelerator that emits charged particles and targets. Regardless of whether it is a nuclear reaction or not, what is produced is in fact a mixed radiation field, i.e. The beam includes low to high energy neutrons and photons. Regarding boron neutron capture therapy, the higher the content of other radiation, except for epithermal neutrons, the higher the The greater the number of doses, the greater the proportion of non-selective dose deposition in normal tissues. It is necessary to reduce as much as possible the radiation that causes the necessary dose. Avoid too much radiation in the tissue, which may also result in unnecessary dose deposition. It should be.

[0071] The neutron beam N generated by the neutron generator 11 is passed through the beam shaper 12 and the collimator 13 in order. The beam passes through the beam shaper 13 and is irradiated onto the subject 200 on the treatment table 14. The beam quality of the neutron beam N generated by the neutron generator 11 can be adjusted. The meter 13 collects the neutron beam N and provides high targeting of the neutron beam N during treatment. As can be seen, the present invention does not have a collimator, but rather focuses the beam from the beam shaper 12. After exiting the treatment table 14, the subject 200 on the treatment table 14 may be directly irradiated with the radiation.

[0072] The beam shaper 12 includes a reflector 121, a moderator 122, a thermal neutron absorber 123, and a radiation shield. The neutron generating device 11 further includes a shield 124 and a beam outlet 125. In addition to epithermal neutrons, which have a wide energy spectrum and can meet the needs of treatment, other types of neutral The content of electrons and photons must be reduced as much as possible to prevent damage to the operator or the irradiated body. Therefore, the neutrons emitted from the neutron generator 10 pass through a moderator 22. The energy of fast neutrons (>40keV) is in the epithermal neutron energy region (0.5eV~ 40 keV) and epithermal neutrons (<0.5 eV) must be reduced as much as possible. The moderator 22 has a large cross section that interacts with fast neutrons and a small cross section that interacts with epithermal neutrons. In a preferred embodiment, the decelerator 122 is made of a material having a small diameter. 2 O, AlF 3 , Fluental®, CaF 2 , Li 2 CO 3 , MgF 2 and Al 2 O 3 brain The reflector 121 is made of at least one of the above materials. The reflector 121 surrounds the decelerator 122 and is The neutrons that pass through 2 and are scattered around are reflected back into the neutron beam N to improve the neutron utilization rate. The reflector 121 is preferably made of a material having a high neutron reflectivity. The moderator 122 is made of at least one of the following materials: B or Ni; and the moderator 122 has a thermal neutron absorber at the rear. 123, which is made of a material with a large cross section that interacts with thermal neutrons, and is the preferred embodiment. The thermal neutron absorber 123 is made of Li-6 and absorbs the thermal neutrons that have passed through the moderator 122. This reduces the thermal neutron content in the neutron beam N, and reduces the amount of thermal neutrons in the superficial normal tissue during treatment. As can be seen, the thermal neutron absorber is a moderator. The material of the moderator may include Li-6, and the radiation shield 124 may be a bead. The material of the radiation shield 124 blocks neutrons and photons leaking out from the parts other than the radiation exit 125. The material includes at least one of a photon shielding material and a neutron shielding material, and in a preferred embodiment The material of the radiation shield 124 is lead (Pb) which is a photon shielding material and poly (poly) which is a neutron shielding material. The collimator 13 is disposed behind the beam outlet 125. The epithermal neutron beam emitted from the meter 13 is irradiated to the subject 200 and passes through the superficial normal tissue. After passing through the tumor, the neutrons are decelerated to thermal neutrons and reach the tumor cells M. As can be seen, the beam is shaped The body 20 may also be of other structure, provided it obtains the epithermal neutron beam required for treatment. For ease of explanation, when the collimator 13 is installed, the output of the collimator 13 The aperture can also be regarded as a beam exit 125, which will be described later. A radiation shielding device 15 is further installed between the beam exit 120 and the beam exit 125. The beam emitted from 5 is shielded from the normal tissue of the subject, and as can be understood, the radiation The radiation shielding device 15 does not necessarily have to be installed.

[0073] The subject 200 is administered or injected with a boron (B-10)-containing drug, and then the boron The boron-containing drug selectively accumulates in the tumor cells M, and then the boron (B-10)-containing drug is absorbed by thermal neutrons. Taking advantage of the high capture cross-sectional area of 10B(n,α) 7 Li neutron Through capture and fission reactions, 4 He and 7 It generates two types of heavy charged particles, Li. The charged particles have an average energy of about 2.33 MeV and a high linear energy transfer (Li It has the characteristics of near Energy Transfer (LET) and short range. The linear energy deposition and range of alpha particles are 150 keV / μm and 8 μm, respectively. 7 L The linear energy deposition and range of the i-heavy charged particle are 175 keV / μm and 5 μm, and there are two types The total range of the particles is equivalent to the size of about one cell, so radiation damage to living organisms is at the cellular level. The aim is to partially kill tumor cells while suppressing the release of inflammatory cytokines and without causing significant damage to normal tissue. The goal can be achieved.

[0074] The boron neutron capture therapy system 100 is entirely contained within a concrete structure. Specifically, the boron neutron capture therapy system 100 includes an irradiation chamber 101 and a charged particle The irradiation chamber 101 further includes a beam generating chamber 102, and the irradiation subject 200 on the treatment table 14 is The neutron beam N is irradiated in the charged particle beam generating chamber 102, which is an accelerator 1 11, and the beam shaper 12 is connected to the irradiation chamber 101 and the charged particle beam The generation chamber 102 is at least partially contained within a partition wall 103. The partition wall 103 completely separates the irradiation chamber 101 from the charged particle beam generation chamber 102. The charged particle beam generating chamber 102 may be partially separated from the irradiation chamber 101 by a The irradiation chamber 101 and the charged particle beam generation chamber 102 are connected to each other. may be one or more, and the charged particle beam P may be selectively one or more of them. Either one target T acts on the other or multiple targets T act simultaneously, producing one or more The therapeutic neutron beam N is generated. Depending on the number of targets T, the beam shaper 12, The collimator 13 and the treatment table 14 may be one or more. The treatment tables may be the same. The irradiation room may be installed in the same room as the treatment room, or each treatment table may be provided with a separate irradiation room. The charged particle beam generating chamber 102 and the charged particle beam generating chamber 101 are surrounded by a concrete wall W (including a partition wall 103). The concrete structure is a space that is enclosed and can withstand the operation of the boron neutron capture therapy system 100. It can block neutrons and other radiation that escape during the process.

[0075] This is a treatment plan that can maximize cancer cell killing while reducing radiation damage to normal tissues. In the setting of the imaging module 20, the accuracy of the dose distribution of epithermal neutrons and photons is very important. In the application of radiation irradiation systems, dose calculations are based on photon and neutron cross section data. The neutron cross section database is very large, so the radiation exposure The installation of the system's treatment planning software takes up a large amount of storage space. And the memory occupied when performing dose calculation simulation using the software The following embodiment of the present invention uses a series of treatment planning modules. It provides a method to optimize the software to reduce the execution memory and dose calculation time. This meets the demand for quickly creating a radiation therapy planning scheme. Each optimization method will be explained. EXAMPLES

[0076] The database is optimized in the treatment planning module 20 .

[0077] The human body contains a total of 60 elements, of which 20 are essential. It is an element that plays an important role in maintaining the normal physiological functions of the human body. The elements with high abundance are carbon, hydrogen, oxygen, nitrogen, phosphorus, chlorine, sodium, magnesium, Potassium, calcium, etc., and carbon, hydrogen, oxygen, and nitrogen make up the organic matter of the human body. It is a major element, accounting for 96% of the total weight of the human body, and the remaining large amounts in the human body are less than 0.01%. The elements are calcium, potassium, phosphorus, sulfur, chlorine, magnesium, and sodium. The percentages of the total human body weight that they occupy are 1.5%, 0.35%, and 1%, respectively. , 0.25%, 0.15%, 0.05%, and 0.15%. From the above, carbon, hydrogen, and acid Content of calcium, nitrogen, calcium, potassium, phosphorus, sulfur, chlorine, magnesium, and sodium The amount of elements has already reached 99.45% of the total weight of the human body, and the Monte Carlo simulation of more than 100 elements has been carried out. The simulation and calculation system is stored and simulated using Monte Carlo every time. When performing simulations and calculations, each element is simulated and calculated. It takes a long time to calculate and simulate many elements. However, the Monte Carlo database is very large because the In the application of the system, Monte Carlo is used to measure the behavior of particles such as photons and neutrons inside the human body. In contrast, when performing simulation calculations, the percentage of the total human body weight is large (0.01 Accurate calculation results can be obtained simply by performing simulation calculations on elements in the human body (greater than 10%) The simulation calculation for some trace elements took a long time. The calculation results are based on simulations of elements that account for more than one ten-thousandth of the total weight of the human body. The difference values ​​are within 0.001% compared to the results obtained by performing the simulation calculation.

[0078] In addition, some elements, such as Fe, have a large weight ratio in the human body, but are not affected by neutrons and photons. Since these elements do not react with ions or have a low reaction strength with neutrons and photons, stains of these elements are not observed. The effect of the simulation results on the overall calculation results may be ignored. For example, boron has a small weight ratio in the human body, but it is used in radiation irradiation systems. In this study, a large amount of boron was injected into the human body, and the reaction with neutrons was intense. The impact on the results is significant.

[0079] The weight percentage of elements in the human body and their reaction strength with neutrons and photons are taken into consideration when determining the degree of radiation exposure. Impact on neutron and photon simulation calculation results in the application scene of the system Elements with impact (H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, S I, P, S, Cl, Ar, K and Ca) During the simulation process, only the screened elements are simulated. By applying this function, the simulation calculation time is reduced while ensuring the accuracy of the calculation. , it is possible to improve the efficiency of Monte Carlo execution, and also to screen these The database capacity for these elements is only 2%-3% of the original database capacity. The memory requirements of magnetic disks are significantly reduced, reducing manufacturing costs.

[0080] On the other hand, the neutron cross section database for each element is based on the Monte Carlo system. There are many temperatures for selection, for example, 0K, 1200K, 2500K, 250K, Cross-sectional data corresponding to 294K, 600K, and 900K are stored. In the application scenario of the system, simulation calculations are performed only on the human body model. The normal temperature of the human body is 310K to 315K. Based on the Monte Carlo principle, After the temperature is entered, the system will automatically calculate the temperature at the number of temperatures stored. Automatically match the temperature closest to the temperature you selected, and set that temperature as a simulation parameter. After the temperature of the human body is input, the system performs simulation calculations as the data. The temperature of 294K stored in the database is matched, and 294K is used as a parameter. The simulation calculation is performed using the temperature. , 0K. In other words, in the application scene of the radiation irradiation system, Of the temperatures listed, only two, 294K and 0K, were used. The other temperatures were determined by the irradiation. For temperatures other than 294K and 0K, it is unnecessary for the application scene of the radiation system. The corresponding database is removed, and the data is deleted without affecting the simulation calculation structure. Reduces database size to approximately one-third of original size, lowering database running costs .

[0081] Table 1 shows the results of the Monte Carlo system at temperatures of 294K, 310K, and 330K, respectively. This is the result of a neutron dose simulation calculation performed on the same human body model.

[0082] [Table 1]

[0083] As can be seen from the data in Table 1, the final calculation of the neutron dose due to small range variations in temperature The effect on the results can be ignored, and in the application scene of the radiation irradiation system, By simply reserving the database corresponding to the 294K stored, the usage request can be met. and the error in the final calculation result is within an acceptable range. EXAMPLES

[0084] During the particle simulation process, the process is shut down to reduce the particle simulation time. Reduces.

[0085] In the application scene of the radiation irradiation system, the dose calculation is performed by neutron dose calculation and photon dose calculation. Photons lose their photon energy and photon half-life during their movement through the body of the irradiated object. The absorption thickness gradually decreases, but the photon absorption cross section increases with photon energy and photon half-absorption thickness. When the half-absorption thickness of a photon is smaller than the size of a single cell, The probability that a photon will be absorbed in the cell in which it resides is very large. We directly set up the deposition of all energy in the cells in which it is located, and simulated Instead of continuing the simulation, we continued the simulation of the dose distribution and photons calculated after such processing. The error between the dose distribution calculated by the method and the actual dose distribution is within 0.1%.

[0086] The size of human cells is 2 to 200 μm, and in general, in the application of radiation irradiation systems, If the minimum dimension of the model grating is 0.8 mm, the half-absorption thickness of the photon is the minimum dimension of the grating. If the photon is less than a quarter of

[0087] Specifically, calculate the half-absorption thickness t of the photon using equation (1-1),

number

[0088] Below, we take the human skeleton as an example to calculate the half-absorption thickness in the skeleton for different photon energy values. do.

[0089] [Table 2]

[0090] As can be seen from Table 2, in the skeleton, when the photon energy is less than 10 KeV, The half-absorption thickness of the photon is less than 0.2 mm, i.e., the photon energy is less than 10 KeV. In this case, the photon is very likely to be absorbed in the lattice where it is currently located, If this is the case, the simulation of the photons is stopped and the obtained dose and the photons are further simulated. The difference between the dose obtained by scanning and the dose obtained by the CT scan is within an acceptable range.

[0091] The half-absorption thickness of a photon in tissue is determined by the material it passes through and the photon energy. Therefore, it is possible to set the cutoff energy corresponding to various materials, and the photon emission Stop simulating photons if their energy is lower than this cutoff energy. The following describes the settings based on a simulation calculation using a human body model. The photon doses corresponding to the different photon cutoff energies are obtained.

[0092] [Table 3]

[0093] As can be seen from Table 2, when the photon energy is below 10 KeV, the photon simulation The simulation calculation is stopped, and the final calculated photon dose and the photon simulation calculation are continued. The error with the subsequently obtained dose distribution is within 0.1%.

[0094] From the above, in the process of photon simulation calculation, the photon energy is When the photon half-absorption thickness is smaller than the size of a cell, In this case, the photon simulation is stopped and the dose distribution calculation results are not affected. This can significantly reduce the calculation time for the photon dose.

[0095] In another embodiment, the first predetermined value and A second predetermined value is set, and if the half absorption thickness of the photon is equal to or less than the first predetermined value, or if the photon emission If the energy is less than or equal to a second predetermined value, the simulation of the photon is stopped and the first predetermined value is reached. The value may be greater than the size of one cell or less than the size of one cell. , the second predetermined value may be 12 KeV, 16 KeV, etc. EXAMPLES

[0096] Parallel techniques are used to accelerate the dose calculation module.

[0097] The treatment planning module of the radiation delivery system uses the Monte Carlo method to simulate different source particles. The simulation processes are completely independent, i.e., the simulation of different particles The simulation order does not affect the calculation results, and based on such calculation characteristics, the simulation order of different source particles is Assigning simulation tasks to different processes or threads and running each process or thread After completing the calculation tasks of the threads, they are summed up to obtain the final calculation result. It provides two types of parallelism, process parallelism and thread parallelism, and GPU acceleration. This can be done.

[0098] As shown in Figure 3, the so-called CPU process parallel and thread parallel calculation process is First, the system obtains the number of processes or threads to obtain a value n; The system divides the particles to be simulated into n uniform parts, and then Each thread or process independently simulates one particle, and then and finally, counting the number of times the system acquires each process or each thread. and calculating the number of counts to obtain a final dose. The process or thread to be simulated is assigned to the corresponding process or thread, and the simulation is performed. We reduce the application and computation time by simulating all particles using one process or thread. Reduce the time required to run and calculate by a factor of n (process) or 2n .

[0099] Both process parallelism and thread parallelism use multi-core CPUs to perform parallel calculations. GPU acceleration is achieved by the parallel calculation of the multi-core processor of the GPU. The process and thread parallelism is limited by the CPU cost. In the case of a single-core processor, the number of cores is four. Thus, process parallelism and thread parallelism have the same speed. The number of processes can be increased by up to 4 times (processes) or 8 times (threads), and one GPU can handle multiple processes. As processors are integrated, the calculation speed can theoretically be increased several times.

[0100] As shown in Figure 4, the process of so-called GPU-accelerated simulation calculations is as follows: The system transfers random numbers, cross-sectional area data, etc. from the CPU memory to the GPU graphics memory. Then, each processor in the GPU simulates, calculates, and counts a single particle. and counting the counted number into a global count; and Determine whether there are any particles that have not been simulated, and If there are no particles remaining, the counting results are transferred from the GPU memory to the CPU memory and the simulation is performed. If there are any particles that have not been simulated, go back to the previous step and simulate all the particles. Continue simulating the unsimulated particles until the simulation is complete. and a counting step.

[0101] Since there are many GPU processors, GPU-accelerated simulation calculations have a high calculation speed. This significantly improves the calculation time and reduces the cost of the CPU. 00 original Intel Xeon processor with 2.27GHz The GPU uses the NVIDIA Tesla C2050, which costs about 9,000 yuan. Each GPU has a total of 448 processors, The calculation time of a CPU is 50 to 70 times that of a GPU. Therefore, compared to CPU, the cost and cost of using GPU for simulation calculations are reduced. This gives the system a significant advantage in terms of time. EXAMPLES

[0102] A Monte Carlo variance reduction method is used to speed up and converge.

[0103] The Monte Carlo method has a rich variance reduction method to improve the program's calculation speed. The variance reduction methods available for treatment planning systems are implicit absorption, weight window games, Russian roulette and splitting, etc. The splitting technique consists of Russian roulette and splitting techniques. Russian roulette method of variance reduction, splitting method, lattice space importance, Interpreting the implicit absorption and wait window game.

[0104] For the Russian roulette method, the weights of the particles are usually set to an upper bound of 10 and a lower bound of is set to 0.25. If the particle weight w is smaller than some predefined value (e.g., 0.25), If the number of samples falls to w, a random number x is sampled from 0 to 1. If x is smaller than w, the grain size is If the child survives, the particle's weight returns to 1, and if x is greater than or equal to w, the particle is annihilated and the particle's system is End the simulation.

[0105] For the splitting method, if the particle weight w is greater than a certain value (e.g., 10), If so, set the integer part of w to w1, the decimal part to w2, and sample a random number x from 0 to 1. If x is less than w2, set w=w1+1, and if x is greater than w2, set w=w 1, then split one particle into w particles, lowering the weight of each particle to 1. The simulation is carried out until the

[0106] For the lattice spatial importance, the dose contributions due to particles in different regions of the model are ,There are differences, and the contribution of the dose due to the particle is expressed by spatial importance, and the simulation Before this, we first calculate the lattice space inference for each lattice based on parameters such as tumor location and model characteristics. The particle is calculated by the lattice space importance I n From the lattice to the lattice space Portance is I n+1 Move to the grid of I n+1 >I n If so, m = I n+1 / I n To Then, the particle is split into m particles, and the weight of each particle is reduced to 1 / m of the original. I n+1 n If so, we can play Russian roulette on the particles and get P=I n+1 / I n Then, sample a random number x between 0 and 1. If x is smaller than P, a particle is generated. If it remains, multiply the weight by 1 / P. Otherwise, the particle is annihilated and the particle simulation is Exit the program.

[0107] Regarding the calculation method of lattice space importance, the lattice space importance is calculated by the adjoint bundle. The adjoint flux is obtained by solving the adjoint transport equation ,

number

[0108] In the case of implicit absorption, when a particle interacts with a substance, the particle has no choice but to scatter and is not absorbed. Each time a particle collides, it is not concentrated, and the weight of the particle is increased by P 散乱 / P 総 Multiply by a value that weights the particle (e.g. For example, if the β drops to 0.25, the particles are treated in a Russian roulette fashion.

[0109] For weight window games, if the particle's weight is greater than a certain value, e.g., 10, In this case, a splitting method is performed and if the particle weight is smaller than a certain value, e.g., 0.25, In this case, we play Russian roulette. The two values ​​are based on the software performance. It is set.

[0110] In summary, particles move from a point with small lattice space importance to a point with large lattice space importance. When the chest moves to a large area, the weight of the particles increases, the particles do not disappear, and the weight decreases In this case, the particle moves from the point where the lattice space importance is large to the point where the lattice space importance is large. When the transformer moves to a small area, the weight of the particle decreases and the particle splits. The absorption cross section of thermal neutrons in the human body (mainly elements such as N and B) is ) is large, so in order to accelerate the convergence speed of dose calculations for lattices far from the neutron source, Implicit absorption should cause the particles to move into these lattices. In this case, continuing the particle simulation is of great significance for dose calculation in the treatment area. In this case, continuing the calculation would waste computational resources, so the grid space import is Setting up a counter reduces the likelihood of this happening. If the weight of is too small, the contribution of the particle to the count is very small, and the simulation Continuing to do so would waste computational resources, and if the particle weights are too large, a single count There is a risk of making the weight win too large and producing erroneous results. Therefore, it is necessary to set the weight of the particle in an appropriate range by setting the weight of the particle. In addition, we will set the lattice space importance and weight window game rationally. It is necessary to accelerate the convergence rate of the Monte Carlo program by

[0111] As shown in Figure 5, the flow of simulating particles using the variance reduction method is as follows: Step S1 obtains a child, and determines whether the particle collides within the lattice cell. If it collides, If it is determined that there is no collision, steps S3 and S4 are executed in sequence. If it is determined that there is no collision, step Step S2 executes S5 and S6 in order, step S3 executes implicit absorption processing, and weights are It is determined whether the value is lower than the wait window, and if it is determined to be lower, step S7 is executed. If it is determined that the number is not low, the process returns to step S2. Step S4 and Russian Roulette are performed. Step S5 performs splitting and splitting processing, and step S6 performs Russian roulette processing or not. If it is determined that Russian roulette processing is to be performed, step S7 is executed. If it is determined that the cyan roulette process is not to be performed, the process returns to step S2, and step S6 and If it is determined that the object is to be deleted, step S8 is executed. If it is determined that the user should not be allowed to enter the password, the process returns to step S2 after executing step S9. 7, and judge whether the processing of the particles is completed. If it is determined that the processing is completed, the flow is ended. If it is determined that the process is not complete, the process returns to step S1. Step S8 and the weight is set to the extinction probability. and a dividing step S9.

[0112] As shown in Figure 6, the flow of Russian roulette and splitting is A step S1 of calculating and recording child space importance and a step of obtaining particles S2, a step S3 of performing weight window detection and manipulation on the particles, and a step S4 of performing weight window detection and manipulation on the particles. Lattice space importance before and after crossing child boundary I n and I n+1 Step S4 of calculating , I n I n+1 A comparison is made to see if it is greater than the original value, and if it is not greater than the original value, step S6 is executed. Then, return to step S3, and if it is larger, execute step S7. Step S5 and the particle Step S6 of splitting and lowering the weight of the particle, and step S7 of annihilating the particle. If it is determined that the particle is to be annihilated, step S9 is executed to annihilate the particle. If it is determined that the user should not be allowed to enter the password, the process returns to step S3 after executing step S8. 7, step S8 of increasing the weight of the particle, and whether the simulation of the particle is completed or not If it is determined that the simulation is not completed, the process returns to step S2. and step S9 of terminating the simulation if it is determined that the simulation is complete.

[0113] As shown in FIG. 7, the flow of implicit absorption is as follows: step S1 acquires particles; It is judged whether or not a collision will occur within the cell. If it is judged that a collision will occur, step S3 is executed. If it is determined that there is no collision, the process returns to step S1. Then, in step S2, the probability of scattering is added to the weight. Step S3: Determine whether the weight of the particle is smaller than the lowest weight. If it is smaller, If so, execute step S5; if not, return to step S2 Step S4: Determine whether or not to annihilate the particle. If it is determined that the particle is to be annihilated, Step S7 is executed, and if it is determined that the particle is not to be annihilated, step S6 is executed. Then, the process returns to step S2, step S5, and step S6, in which the weight is divided by the annihilation probability. Determine whether the simulation is complete and if it is not, If the simulation is completed, the process returns to step S1. If the simulation is completed, the process ends. and step S7.

[0114] As shown in Figure 8, the flow of the Wait Window game is to simulate particle motion. Step S1 of checking whether the weight of the particle is within a weight window range; If it is determined that the object is within the range, the process returns to step S1. If it is determined that the object is not within the range, the process returns to step S2. Step S2 executes step S3 and determines whether the weight is greater than the weight window. If it is determined that the value is larger, step S4 is executed, and then the process returns to step S1. Step S3 executes step S5 if it is determined that the particles are not split. Step S4 reduces the weight, and then it is determined whether to eliminate the object. If it is determined that the program is to be terminated, and not to be deleted, step S6 is executed, and then step S1 is executed. and step S6 of increasing the weights of the particles.

[0115] To compare the acceleration effect of the variance reduction method on dose calculations, we used implicit absorption and The calculation time and the standard deviation of the results are compared with those without implicit absorption. For the model, the calculation time for 10 million particles and the implicit absorption method is 158 4s, the standard deviation of the dose calculation is 11%, and the calculation without the implicit absorption method The time is 1258s, the standard deviation of the dose calculation is 14.5%, and the standard deviation is implicit absorption In order to reduce the standard deviation to the same as when using the method, The number of particles was increased to 16 million, and the simulation calculation time was increased to 2045 seconds. This increases the calculation time by 461 seconds compared to when the implicit absorption method is used. In other words, the calculation time is reduced by about 20% when the implicit absorption method is used. EXAMPLES

[0116] Simulation calculations are performed using a non-uniform rectangular grid.

[0117] Conventional human body model calculations often use uniform grids, which can lead to poor accuracy in subregions. For dense calculations, the number of grids must be increased, which increases the calculation time and The row memory grows exponentially. The results obtained from these experiments tend to be uniform lattices, with many of the connecting regions being made of the same material. , e.g., air, blood, etc., and for some of these regions, fine doses are Since the distribution does not need to be calculated precisely, a coarse grid can be substituted for a fine grid, and tumors can be For important positions such as these, it is necessary to divide the grid into finer ones to achieve more accurate calculations. It is necessary to calculate the dose using a non-uniform grid to improve the calculation accuracy and reduce the calculation time. The calculation time and memory required for execution do not increase significantly, and the calculation time does not increase significantly. Improve the calculation accuracy and reduce the calculation time when the calculation accuracy of non-critical areas is satisfied. This can be done.

[0118] Below, we set grids of different dimensions and performed simulation calculations to determine the effect of different grid dimensions. The effects of the two on simulation time and calculation accuracy are compared.

[0119] [Table 4]

[0120] In this experiment, the mixing grid used was in the direction of the neutron incidence and was located 5 cm in front of the grid. The first 5 cm section is made up of a 0.4 mm grid, and the middle 5 cm section is made up of a 0.8 mm grid. The remaining part is made up of a 1.6 mm grid, and as can be seen from Table 3, a non-uniform grid is used. By using this method, the total number of lattices is reduced to 2 / 5 of the number of the original 0.4 mm lattices, and the required number of lattices is The memory required is reduced to 1 / 3 of the original, and the calculation time is reduced to 34.7% of the original. The results obtained by calculation using the .4 mm grid were used as a reference and the results were calculated using the mixed grid. The calculated results have a neutron error of less than 0.1% and a photon error of less than 0.2%. Less than %.

[0121] The configuration pattern of the mixed grating is not limited to the above-mentioned patterns, and may be changed depending on the specific object to be irradiated. In general, the size of the grid can be determined based on the importance of the area. For example, the grid of the area where the tumor is located is small, with grids of 4 mm or less. The grid of blood, air and bone regions is large, measuring 1.6 mm or less. The dimensions of the grid in the area where other normal muscle tissues are located are set to 0.8 mm or less. It is set to be smaller than 1.6 mm at most.

[0122] The algorithm used for dose calculation is the Monte Carlo algorithm, The advantage of the algorithm is high calculation accuracy, but the disadvantage is that the convergence speed is slow and the calculation time is long. Since the calculation is long, optimization of the calculation efficiency is the most important part. The optimization methods can improve computational efficiency and reduce computation time to different degrees.

[0123] The above describes exemplary specific embodiments of the present invention so that those skilled in the art can easily understand the present invention. However, the present invention is not limited in scope to specific embodiments, and those skilled in the art will readily appreciate that the present invention is not limited in scope to specific embodiments. Therefore, various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims. These variations are obvious and all fall within the scope of the present invention.

Claims

1. 1. A radiation delivery system comprising: A treatment beam is generated, and the treatment beam is irradiated onto an irradiated body to form an irradiated area. a beam irradiation device; A dose simulation is performed based on the parameters of the treatment beam and the medical image data of the irradiated area. Simulation calculations are performed, and a treatment plan is created. The weight ratio of elements in the human body and neutral Taking into account the reaction strength between the electrons and photons, Screening of elements that have an impact on the results of neutron and photon simulation calculations Then, during the simulation process, only the screened elements are simulated. a treatment planning module for a control module for controlling irradiation of the beam irradiation device based on the treatment plan. A radiation irradiation system comprising:

2. The elements screened by the treatment planning module are H, He, Li, Be. , B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca 2. The radiation irradiation system according to claim 1, wherein the selected element is one or more elements. Stem.

3. The elements screened by the treatment planning module are H, He, Li, Be. , B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca.

3. The radiation irradiation system according to claim 2 .

4. The treatment planning module selects 294 neutron cross sections from the corresponding neutron cross section database for each element. The database corresponding to temperatures other than K and 0 K is removed.

4. The radiation irradiation system according to any one of claims 3 to 4.

5. A neutron capture therapy system, the beam irradiation device comprising a neutron generator, a beam shaping device, the neutron generator includes an accelerator and a target, accelerates charged particles to generate a charged particle beam, and generates a neutron beam by interacting with the target. The beam shaper shapes the neutron beam generated by the neutron generator into a predetermined shape. The neutron beam generated by the neutron generator is adjustable to the beam quality. The present invention is characterized in that the radiation passes through a medical device and is irradiated to the subject on the treatment table.

4. The radiation irradiation system according to any one of 1 to 3.

6. A method for controlling a radiation irradiation system, the beam irradiation system comprising: and irradiating a subject with the therapeutic beam to form an irradiated area. and calculating a dose based on the parameters of the treatment beam and medical image data of the irradiated area. A treatment planning module that performs simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on a plan; The method for controlling the radiation irradiation system includes determining the weight ratio of elements in the human body and the amount of neutrons and photons. In terms of the application of radiation irradiation systems, the strength of the reaction with neutrons and photons is taken into account. Screening elements that have an influence on the simulation results and During the simulation process, a step is added to simulate only the screened elements.

23. A method for controlling a radiation irradiation system, comprising:

7. The elements screened by the treatment planning module were: H, He, Li, Be, Selected from B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca.

7. The radiation irradiation system according to claim 6, wherein the element is one or more selected from the group consisting of How to control the system.

8. The elements screened by the treatment planning module are H, He, Li, Be. , B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca.

8. The method for controlling a radiation irradiation system according to claim 7, further comprising:

9. The treatment planning module selects neutron cross sections for each element from the corresponding neutron cross section database for 294K and and removing a database corresponding to a temperature other than 0 K. The method for controlling a radiation irradiation system according to any one of claims 6 to 8.

10. The radiation irradiation system is a neutron capture therapy system, and the beam irradiation device includes: The neutron generator includes an accelerator and a treatment table. The accelerator accelerates charged particles to generate a charged particle beam, and the target The beam shaper interacts with the target to generate a neutron beam, and the beam shaper is The neutron beam generated by the neutron generator can be adjusted to a predetermined beam quality. The generated neutron beam passes through the beam shaper and is irradiated onto the subject on the treatment table. The method for controlling the radiation irradiation system according to any one of claims 6 to 8, Law.

11. A treatment beam is generated, and the treatment beam is irradiated onto an irradiated body to form an irradiated area. a beam irradiation device; A dose simulation is performed based on the parameters of the treatment beam and the medical image data of the irradiated area. A treatment planning module for performing a simulation calculation and creating a treatment plan, The simulation tasks of the source particles are assigned to different processes or threads, and each process After each process or thread completes its calculation task, they are combined to obtain the final calculation result. a treatment planning module; a control module for controlling irradiation of the beam irradiation device based on the treatment plan. A radiation irradiation system comprising:

12. A neutron capture therapy system, the beam irradiation device comprising a neutron generator, a beam shaping device, the neutron generator includes an accelerator and a target, accelerates charged particles to generate a charged particle beam, and generates a neutron beam by interacting with the target. The beam shaper shapes the neutron beam generated by the neutron generator into a predetermined shape. The neutron beam generated by the neutron generator is adjustable to the beam quality. The present invention is characterized in that the radiation passes through a medical device and is irradiated to the subject on the treatment table.

12. The radiation irradiation system according to claim 11.

13. Particle simulation using CPU process parallelism, thread parallelism and GPU acceleration. Both process parallelism and thread parallelism use multi-core CPUs to perform parallel calculations. In the process parallel and thread parallel calculation process of the CPU, first, the system obtaining a number of threads or a number of threads to obtain a value n; and then the system A step of uniformly dividing the particles to be processed into n pieces, and then each thread or each process The step of simulating and counting each particle independently in each step. Finally, the system aggregates the counts obtained for each process or thread. and calculating the final dose.

13. The radiation irradiation system according to claim 12.

14. GPU acceleration is achieved by the parallel calculation of the GPU's multi-core processor. The process of simulation calculation by CP The U memory is transferred to the GPU graphics memory, and then each processor in the GPU Simulate, calculate, and count particles, and then output the counting results to a global counter. and determining whether the system detects that the unsimulated particles If there are no particles that have not been simulated, the count result is If there are particles that have not been simulated after transferring them from the PU memory to the CPU memory, Return to the previous step and repeat the simulation until all particles have been simulated. and continuing to simulate and count particles that have not been detected.

14. The radiation delivery system according to claim 13.

15. A method for controlling a radiation irradiation system, the beam irradiation system comprising: and irradiating a subject with the therapeutic beam to form an irradiated area. and calculating a dose based on the parameters of the treatment beam and medical image data of the irradiated area. A treatment planning module that performs simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on a plan; The method for controlling the radiation irradiation system includes: and assigning the computational tasks to different processes or threads, and completing the computational tasks of each process or thread. and then summarizing the results to obtain a final calculation result. A method for controlling an illumination system.

16. Particle simulation using CPU process parallelism, thread parallelism and GPU acceleration.

16. The method for controlling a radiation irradiation system according to claim 15,

17. Both process parallelism and thread parallelism use multi-core CPUs to perform parallel calculations.

17. The method for controlling a radiation irradiation system according to claim 16, further comprising:

18. The process of CPU process parallelism and thread parallelism is as follows: first, the system determines the number of processes or The method includes the steps of obtaining the number of threads to obtain a value n, and then the system executes the simulation. A step of dividing the particles to be processed into n evenly, and then dividing each of the threads or processes into n. and independently simulating and counting one particle in each of the Finally, the system collects statistics on the number of counts obtained for each process or thread. and obtaining a final dose by measuring the dose of the target object. A method for controlling a radiation irradiation system.

19. GPU acceleration is achieved by the parallel calculation of the multi-core processor of the GPU. The method for controlling an irradiation system according to claim 16.

20. The process of GPU-accelerated simulation calculation begins with the system generating random numbers, cross-section data, and The data is transferred from the CPU memory to the GPU graphic memory, and then each processor in the GPU The processor simulates, calculates, and counts single particles, and then graphs the counting results. and calculating the global counts, and the system is simulated. If there are no particles that have not been simulated, The simulation results are transferred from the GPU memory to the CPU memory, and the unsimulated particles are If there are any, go back to the previous step and retry the simulation until all particles are simulated. continuing to simulate and count the unsimulated particles; The method for controlling a radiation irradiation system according to claim 19, further comprising:

21. A treatment beam is generated, and the treatment beam is irradiated onto an irradiated body to form an irradiated area. a beam irradiation device; A dose simulation is performed based on the parameters of the treatment beam and the medical image data of the irradiated area. A treatment planning module that performs a simulation calculation and creates a treatment plan, is less than or equal to a first predetermined value. a treatment planning module; a control module for controlling irradiation of the beam irradiation device based on the treatment plan. A radiation irradiation system comprising:

22. A neutron capture therapy system, the beam irradiation device comprising a neutron generator, a beam shaping device, the neutron generator includes an accelerator and a target, accelerates charged particles to generate a charged particle beam, and generates a neutron beam by interacting with the target. The beam shaper shapes the neutron beam generated by the neutron generator into a predetermined shape. The neutron beam generated by the neutron generator is adjustable to the beam quality. The present invention is characterized in that the radiation passes through a medical device and is irradiated to the subject on the treatment table.

22. The radiation irradiation system according to claim 21.

23. The treatment planning module calculates the half-absorption thickness t of the photon by the formula (1-1), [0010] where μ is the linear attenuation coefficient of a photon, which depends on the material the photon passes through and the photon energy.

23. The radiation irradiation system according to claim 21 or 22, wherein the temperature is determined.

24. The first predetermined value is the size of a single cell, and preferably the first predetermined value is 0.2 m m, and if the photon energy is less than or equal to the second predetermined value, the half absorption thickness of the electron is less than or equal to a first predetermined value, and the second predetermined value is 10 KeV; 23. The radiation irradiation system according to claim 21 or 22,

25. A method for controlling a radiation irradiation system, the beam irradiation system comprising: and irradiating a subject with the therapeutic beam to form an irradiated area. and calculating a dose based on the parameters of the treatment beam and medical image data of the irradiated area. A treatment planning module that performs simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on a plan; The method of controlling the radiation irradiation system further comprises the steps of: If the photon is detected as a non-radioactive material, the simulation is stopped. A method for controlling an illumination system.

26. The treatment planning module calculates the half-absorption thickness t of the photon by the formula (1-1), [0025] where μ is the linear attenuation coefficient of a photon, which depends on the material the photon passes through and the photon energy. The method for controlling a radiation irradiation system according to claim 25, wherein the control unit determines a predetermined value of the radiation irradiation system.

27. 27. The method of claim 26, wherein the first predetermined value is the size of a single cell. A method for controlling a radiation irradiation system.

28. 27. The radiation exposure method of claim 26, wherein the first predetermined value is 0.2 mm. How the system is controlled.

29. If the photon energy is less than or equal to a second predetermined value, the half-absorption of the photon corresponding to the photon energy is 26. The radiation exposure system of claim 25, wherein the thickness of the radiation exposure system is equal to or less than a first predetermined value. How the stem is controlled.

30. 30. The radiation exposure method of claim 29, wherein the second predetermined value is 10 KeV. How the system is controlled.

31. A treatment beam is generated, and the treatment beam is irradiated onto an irradiated body to form an irradiated area. a beam irradiation device; A dose simulation is performed based on the parameters of the treatment beam and the medical image data of the irradiated area. A treatment planning module that performs a simulation calculation and creates a treatment plan, a treatment planning module that simulates particles through reduction; a control module for controlling irradiation of the beam irradiation device based on the treatment plan. A radiation irradiation system comprising:

32. The variance reduction is based on the implicit absorption, the weight window game, Russian roulette, and and splitting the radiation delivery system, the radiation delivery system being a neutron capture therapy system. The beam irradiation device includes a neutron generator, a beam shaper, and a treatment table. The generator includes an accelerator and a target, the accelerator accelerating the charged particles to generate the charged particles. a beam shaper for generating a neutron beam and interacting with the target to generate a neutron beam; The neutron beam generated by the neutron generator can be adjusted to a predetermined beam quality. The neutron beam generated by the neutron generator passes through the beam shaper and is projected onto the treatment table.

32. The radiation irradiation system according to claim 31, wherein the radiation irradiation object is irradiated with radiation of about 1000 nm. 。

33. A method for controlling a radiation irradiation system, the beam irradiation system comprising: and irradiating a subject with the therapeutic beam to form an irradiated area. and calculating a dose based on the parameters of the treatment beam and medical image data of the irradiated area. A treatment planning module that performs simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on a plan; The method of controlling the radiation irradiation system further comprises: A method for controlling a radiation irradiation system, comprising the step of simulating Law.

34. The variance reduction is based on the implicit absorption, the weight window game, Russian roulette, and simulating the particles by variance reduction includes splitting the Step S1 of acquiring one source particle; determining whether the particle collides within a lattice cell; If it is determined that a collision will occur, steps S3 and S4 are executed in order. If it is determined that a collision will not occur, Step S2 in which steps S5 and S6 are executed in sequence, and step S3 in which an implicit absorption process is executed. Then, determine whether the weight is lower than the weight window. If it is lower, step If it is determined that the temperature is not low, the process returns to step S2. Step S5 performs a Russian roulette and splitting process; If it is determined that the Russian roulette process is to be performed, step S7 is performed. If it is determined that the Russian roulette process is not to be performed, the process returns to step S2. Step S6 is performed to determine whether or not to delete the object. If it is determined that the object should be deleted, step S8 is performed. If it is determined that the data should not be erased, step S9 is executed and then the process returns to step S2. Step S7: Determine whether the particle processing is complete. If it is complete, If it is determined that the process is not completed, the process returns to step S1. and a step S9 of dividing by the annihilation probability. A method for controlling a firing system.

35. The Russian roulette and splitting are performed by calculating the lattice space importance of each lattice. A step S1 of calculating and recording, a step S2 of acquiring particles, and a step S3 of applying a U to the particles Step S3 performs weight window detection and manipulation, and the lattice boundary before and after the particle crosses the lattice boundary is detected. Spatial Importance I ｎ and I ｎ＋１ Step S4 of calculating I ｎ I ｎ＋１ Greater than If it is not greater, step S6 is executed and then the process returns to step S3. , if it is larger, execute step S7; step S5 and split the particle; Step S6 reduces the weight of the particle, and then determines whether to annihilate the particle. If it is determined that the particle is to be annihilated, step S9 is executed. If it is determined that the particle is not to be annihilated, After executing step S8, return to step S3. Step S7 and increase the weight of the particle. Step S8: determining whether the particle simulation is completed or not and If it is determined that the simulation is not completed, the process returns to step S2. and if it is determined that the step S1 has been completed, the step S2 ends the process. A method for controlling the radiation irradiation system described above.

36. The implicit absorption includes steps S1 of acquiring particles and determining whether the particles collide within a lattice cell. If it is determined that a collision will occur, step S3 is executed. If it is determined that a collision will not occur, , return to step S1, step S2, and step S3 of multiplying the weight by the probability of scattering occurrence. Determine whether the particle's weight is smaller than the lowest weight. If it is smaller, step If it is determined that the particle size is not small, the process returns to step S2. If it is determined that the particle is to be annihilated, step S7 is executed. If it is determined that the particle is not to be annihilated, step S6 is executed and then the process returns to step S2. Step S5, step S6 of dividing the weight by the annihilation probability, and the simulation of the particle is completed. If it is determined that the simulation is not completed, the step S 1, and if it is determined that the simulation is completed, the process ends at step S7.

35. The method for controlling an irradiation system according to claim 34, further comprising:

37. The wait window game includes a step S1 of simulating particle motion, and a step S2 of Determine whether the weight of is within the weight window range, and if it is determined to be within the range, , returning to step S1, and if it is determined that the value is not within the range, executing step S3. S2 and determine whether the weight is greater than the weight window. If it is determined that the weight is greater, After executing step S4, the process returns to step S1. If it is determined that the value is not larger, step Step S3 of performing S5 and a step of splitting particles and lowering weights S4: Determine whether to erase the object. If it is determined that the object should be erased, the process ends. If it is determined that the particle size is not large, the process returns to step S1 after executing step S6. and a step S6 of increasing the weight of the child. A method for controlling a radiation irradiation system.

38. The grid spatial importance is obtained by solving the adjoint transport equation: [0030] In the formula, Φ ＊ is the adjoint bundle, and S ＊ is the adjoint source, and v is the velocity of the particle motion. , Ω is the direction of particle motion, and Σ ｔ is the cross section of the reaction when a particle collides with a substance, and Σ ｓ is the scattering cross section, r is the position of the particle, and E is the energy of the particle.

36. The control method of claim 35, wherein t is time. Your method.

39. The particle has a lattice space importance of I ｎ From the lattice of the lattice, the lattice space importance is I ｎ＋１ Movement on the grid of I ｎ＋１ >I ｎ Then, m = I ｎ＋１ / I ｎ Let the particles be m particles. , and the weight of each particle is reduced to 1 / m of the original weight, and I ｎ＋１ <I ｎ in If so, perform Russian roulette on the particle and make P = I ｎ＋１ / I ｎ 0 to 1 Sample a random number x from , and if x is smaller than P, the particle survives and has a weight of 1. If not, the particle is annihilated and the simulation of the particle is terminated. The method for controlling a radiation irradiation system according to claim 38,

40. The particle weight has an upper limit of 10 and a lower limit of 0.25, and the particle weight w is greater than 10. In this case, set the integer part of w to w1, the decimal part to w2, and sample a random number x from 0 to 1. If x is less than w2, set w = w1 + 1. If x is greater than w2, set w = w1, then split one particle into w particles so that each particle has a weight of 1.

40. The method according to claim 34, wherein the simulation is performed until the temperature drops.

2. A method for controlling the radiation irradiation system according to claim 1.

41. A treatment beam is generated, and the treatment beam is irradiated onto an irradiated body to form an irradiated area. a beam irradiation device; A dose simulation is performed based on the parameters of the treatment beam and the medical image data of the irradiated area. A treatment planning module that performs a simulation calculation and creates a treatment plan, a treatment planning module that performs simulation calculations using uniform lattices; a control module for controlling irradiation of the beam irradiation device based on the treatment plan. A radiation irradiation system comprising:

42. The treatment planning module sets the grid size of the important region smaller than the grid size of the non-important region.

42. The radiation irradiation system according to claim 41, wherein the radiation irradiation system is set to a low value.

43. The treatment planning module sets the size of the grid of the area where the tumor is located to 0.4 mm or less.

42. The radiation irradiation system according to claim 41, wherein

44. The treatment planning module sets the grid size of the blood, air and bone regions to 1.6 mm.

42. The radiation irradiation system according to claim 41, wherein the above is set.

45. The treatment planning module reduces the size of the grid of the area where normal muscle is located to less than 0.8 mm.

42. The radiation irradiation method according to claim 41, wherein the distance is set to less than 1.6 mm. system.

46. A neutron capture therapy system, the beam irradiation device comprising a neutron generator, a beam shaping device, the neutron generator includes an accelerator and a target, accelerates charged particles to generate a charged particle beam, and generates a neutron beam by interacting with the target. The beam shaper shapes the neutron beam generated by the neutron generator into a predetermined shape. The neutron beam generated by the neutron generator is adjustable to the beam quality. The present invention is characterized in that the radiation passes through a medical device and is irradiated to the subject on the treatment table.

46. ​​A radiation irradiation system according to any one of claims 41 to 45.

47. A method for controlling a radiation irradiation system, the beam irradiation system comprising: and irradiating a subject with the therapeutic beam to form an irradiated area. and calculating a dose based on the parameters of the treatment beam and medical image data of the irradiated area. A treatment planning module that performs simulation calculations and creates a treatment plan; a control module for controlling irradiation of the beam irradiation device based on a plan; The method of controlling the radiation irradiation system further comprises the step of: A radiation irradiation system comprising: Control methods.

48. The treatment planning module sets the grid size of the important region to be smaller than the grid size of the non-important region.

48. The radiation irradiation system according to claim 47, further comprising a setting step. How to control the system.

49. The treatment planning module sets the size of the grid of the area where the tumor is located to 0.4 mm or less.

48. The control of the radiation delivery system according to claim 47, further comprising the step of: Your method.

50. The treatment planning module sets the size of the grid of blood, air and bone regions to 1.6 mm The size of the grid in the area where normal muscle is located is set to 0.8 mm or more and 1.6 mm or less.

48. The radiation method of claim 47, further comprising the step of setting the radiative density to be less than m. A method for controlling a radiation irradiation system.

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