Dose conversion method, radiotherapy system and related device

Abstract

The present application provides a dose conversion method, an electronic device, a computer-readable storage medium, a computer program product, and a radiotherapy system. The method includes: obtaining first material dose information of a particle; obtaining a conversion relationship between the dose deposition of the particle between a first material and a second material; and converting the first material dose information of the particle into second material dose information according to the conversion relationship. By considering the dose deposition conversion relationship of the particle, the present application quickly and accurately converts the dose information of the particle in different materials. This conversion method has important application values in radiotherapy (such as proton, heavy ion, etc.) and other radiation dose scenarios (such as the field of space radiation dose, etc.), and can realize the comparison and analysis of particle doses in different tissues and media, providing technical support for the optimization and personalization of particle therapy and other radiation dose scenarios.

Description

Technical Field

[0001] This application relates to the technical fields of radiotherapy and space radiation, and particularly to a dose conversion method, an electronic device, a computer-readable storage medium, a computer program product, and a radiotherapy system. Background Art

[0002] Radiotherapy is a medical means used to treat diseases such as cancer. In radiotherapy, the dose deposition of particles is a key parameter, which reflects the distribution of radiation energy in the patient's body. In a radiotherapy plan, doctors need to accurately understand the dose deposition of particles in different tissues and media to ensure the accuracy and safety of treatment.

[0003] In radiotherapy, the output results of existing dose algorithms based on the Monte Carlo method cannot be directly compared and verified with the calculation results of traditional analytical algorithms and the measurement data of clinical water tank experiments, which affects the subsequent development of radiotherapy.

[0004] Based on this, this application provides a dose conversion method, an electronic device, a computer-readable storage medium, a computer program product, and a radiotherapy system to improve related technologies. Summary of the Invention

[0005] The purpose of this application is to provide a dose conversion method, an electronic device, a computer-readable storage medium, a computer program product, and a radiotherapy system, which can quickly and accurately convert the dose information of particles in different materials by considering the conversion relationship of particle dose deposition.

[0006] The purpose of this application is achieved by the following technical solutions:

[0007] This application provides a dose conversion method, and the method includes:

[0008] Obtain the first material dose information of the particle;

[0009] Obtain the conversion relationship between the dose deposition of the particle between the first material and the second material;

[0010] According to the conversion relationship, convert the first material dose information of the particle into the second material dose information.

[0011] The beneficial effects of this technical solution are as follows: By considering the dose deposition conversion relationship of particles, the dose information of particles in different materials can be quickly and accurately converted. This conversion method has important application value in radiotherapy (such as proton, heavy ion, etc.) and other radiation dose scenarios (such as space radiation dose and other fields), and can realize the comparison and analysis of particle doses in different tissues and media. By converting the first material dose of particles into the second material dose, effective dose comparison and data analysis can be carried out between different materials and tissues, providing technical support for the optimization and personalization of particle therapy and other radiation dose scenarios.

[0012] In some possible implementation manners, the conversion relationship is represented by a conversion coefficient table. In the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient, or each particle type corresponds to a conversion coefficient; or,

[0013] The conversion relationship is represented by a conversion coefficient model.

[0014] The beneficial effects of this technical solution are as follows: The conversion relationship can be represented by a conversion coefficient table or a conversion coefficient model. For the implementation manner of the conversion coefficient table, a corresponding conversion coefficient can be set for each combination of particle type and particle energy, or a conversion coefficient can be set for each particle type. In addition, the conversion relationship can also be represented by a conversion coefficient model.

[0015] The method of using a conversion coefficient table can provide a more direct and simple conversion process. By pre-calculating and recording the conversion coefficients under different particle and energy combinations, the corresponding conversion coefficient can be directly looked up according to the given particle and energy information, and the dose information can be converted.

[0016] The method of using a conversion coefficient model describes the dose conversion relationship of particles by establishing a model. For example, the model parameters are determined through experimental data or theoretical derivation, as well as physical processes such as energy loss and interaction of particles in different materials. According to the established model, the corresponding conversion coefficient can be calculated by inputting information such as particles and energy.

[0017] The method of using a conversion coefficient table or a conversion coefficient model to implement the conversion relationship has flexibility and adaptability. The conversion coefficient table can provide direct conversion results and is suitable for simple dose conversion requirements. The conversion coefficient model can more accurately describe the dose conversion relationship and is suitable for complex scenarios (such as more parameters, higher-dimensional non-linear models) and higher accuracy requirements.

[0018] In some possible implementation manners, the particles include one or more of primary particles, secondary electrons, and secondary fragments; or,

[0019] The particle is a proton and / or a heavy ion; or,

[0020] The particle is any charged particle.

[0021] The beneficial effects of this technical solution are as follows: The particles can include one or more of primary particles, secondary electrons, and secondary fragments. Primary particles are the initial incident charged particles (i.e., the particles directly produced by the radiation source), which mainly lose energy through ionization interactions with matter; secondary electrons are derived from the ionization interactions of primary particles, secondary fragments with matter, and lose energy through ionization interactions with matter; secondary fragments are produced by the nuclear reactions of primary particles with matter, and among them, charged nuclear fragments (such as H-2, H-3, He-3, etc.) lose energy through ionization interactions, and uncharged fragments such as neutrons mainly lose energy through elastic and inelastic collisions with matter.

[0022] In addition, the particle can be a proton and / or a heavy ion. A proton is one of the most common particles and is widely used in radiotherapy in the medical field. Heavy ions include alpha particles, carbon ions, etc., which have higher mass and energy and can produce more complex interaction and energy deposition patterns in tissues.

[0023] Alternatively, the particle can also be any charged particle. Charged particles include protons, heavy ions, and other charged particles such as helium ions, lithium ions, etc. The energy loss, the probability of nuclear reactions, and the types and energies of secondary fragments produced by nuclear reactions of these charged particles in different materials are different. Therefore, corresponding dose conversions need to be carried out for different particle types.

[0024] By considering the dose conversion relationships of different particles such as primary particles, secondary electrons, and secondary fragments, as well as the conversion requirements for protons, heavy ions, and other charged particles, this dose conversion method can achieve more comprehensive and extensive particle dose conversions, which is of great significance for the dose calculation and evaluation of particle therapy, can meet the dose conversion requirements under different particles and different treatment scenarios, and improve the accuracy and personalization level of radiotherapy.

[0025] In some possible implementation manners, the first material dose information is the target organ dose information, and the second material dose information is the dose information in water;

[0026] The process of obtaining the first material dose information of the particle includes:

[0027] Obtain the CT data of the patient;

[0028] According to the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from the CT data to the real human body;

[0029] Simulate the transport process of the particles in the target organ of a real human body, and calculate the target organ dose information of the particles after the transport process.

[0030] The beneficial effects of this technical solution are as follows: The first material dose information can be the dose information of the target organ, while the second material dose information can be the dose information in water. The target organ can be any organ, that is to say, for each organ, transport simulation and dose calculation can be performed separately. Specifically, the transport process of the particles in each organ can be simulated separately to obtain the organ dose information corresponding to each organ. Moreover, this method can consider the physical processes of the interaction between the particles and the material and the energy deposition mode, and set different conversion coefficients for different particles, which has high scientificity and accuracy. This dose conversion method is of great significance for accurate dose calculation and radiotherapy planning, and can provide more reliable dose assessment and treatment effect prediction for clinical practice. Therefore, this dose conversion method has broad application prospects in the field of clinical radiotherapy.

[0031] To obtain the target organ dose information of the particles, first, the CT data of the patient can be obtained. By performing a CT scan on the patient, tomographic image data of the patient's body can be obtained. These data can provide density information about different tissues and organs, which is used for subsequent dose calculation and conversion processes. Secondly, tissue material replacement is performed according to the CT data. According to the CT value of each voxel in the CT image, each voxel is replaced with the corresponding real human organ material. This can achieve the mapping from the virtual image to the real human body, and provide specific tissue material properties for subsequent particle transport and dose calculation. After that, the first material dose information of the particles is obtained. By simulating the transport process of one or more particles in the target organ of a real human body, the dose information (the dose information is the dose deposition information, or the dose distribution information) of each particle in the target organ after the transport process can be calculated. This requires considering physical processes such as the interaction between the particles and the tissue material, energy deposition, and parameters such as the initial energy and angular distribution of the particles. Through the above steps, the dose information of the particles in the target organ can be obtained and converted into the dose information in water in the subsequent conversion process. This can facilitate comparison and verification and unified representation of the dose results, and provide accurate data support for the planning and evaluation of particle therapy.

[0032] The advantage of doing this is that by combining CT data and particle transport simulations, dose conversion from the medium (target organ) to water is achieved. This allows for a more accurate assessment of the dose deposition of particles in the target organ and converts it to the dose in water to meet the requirement in clinical practice of expressing the dose as the dose in water. At the same time, this method takes into account the properties of tissue materials and the physical processes of particles, improving the accuracy and reliability of dose calculation. Therefore, this dose conversion method is of great significance for the realization of precise radiotherapy and clinical dose calculation.

[0033] In some possible implementation manners, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the primary particles in the target organ and water;

[0034] The process of obtaining the conversion coefficient between the dose deposition of the primary particles in the target organ and water includes:

[0035] According to the energy of the primary particles and / or the voxel size of dose statistics, obtain the energy threshold for the generation of secondary electrons by ionization interactions;

[0036] According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity of the primary particles, and the energy threshold, respectively calculate the restricted stopping power values of the primary particles in the target organ and water;

[0037] According to the restricted stopping power values of the primary particles in the target organ and water, and the densities of the target organ and water, calculate the conversion coefficient between the dose deposition of the primary particles in the target organ and water.

[0038] The beneficial effects of this technical solution are as follows: The conversion relationship is used to indicate the conversion coefficient between the dose deposition of primary particles in the target organ and water. To obtain the dose deposition conversion coefficient of primary particles, first, obtain the energy threshold for the ionization interaction to generate secondary electrons. According to the energy and / or dose of the primary particles and the voxel size for statistics, determine the energy threshold for the ionization interaction to generate secondary electrons. This threshold is used to screen out secondary electrons with energies higher than the threshold for subsequent dose conversion calculations. Secondly, calculate the restricted stopping power values. According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ, as well as the number of atoms per unit mass, effective atomic number, average ionization energy of water, and the charge, velocity, and energy threshold of the primary particles, calculate the restricted stopping power values of the primary particles in the target organ and water respectively. The restricted stopping power value is related to the energy of the particle, the composition and properties of the substance, etc. Then, calculate the conversion coefficient. According to the restricted stopping power values of the primary particles in the target organ and water, the energy threshold for the generation of secondary electrons, and the densities of the target organ and water, calculate the conversion coefficient between the dose deposition of the primary particles in the target organ and water. The conversion coefficient represents the dose conversion relationship from the target organ to water, which converts the dose in the target organ into the corresponding dose in water. Through the above steps, the conversion coefficient between the dose deposition of primary particles in the target organ and water can be obtained. In this way, the dose in the target organ can be converted into the dose in water, realizing the conversion from tissue dose to water dose. The advantage of doing this is that by considering factors such as restricted stopping power, the density of the substance, as well as the energy of the particle and the voxel size for dose statistics, the dose conversion coefficient can be calculated more accurately, improving the accuracy and reliability of dose calculation and providing support for the realization of precise radiotherapy.

[0039] In some possible implementation manners, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water;

[0040] The process for obtaining the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water includes:

[0041] Judge whether the energy of the secondary electrons is greater than the energy threshold;

[0042] When the energy of the secondary electrons is greater than the energy threshold, calculate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water according to the atomic numbers, mass numbers, densities, average ionization energies of the target organ and water, and the energy of the secondary electrons.

[0043] The beneficial effects of this technical solution are as follows: The conversion relationship is used to indicate the conversion coefficient of the dose deposition of secondary electrons between the target organ and water. In order to obtain the dose deposition conversion coefficient of secondary electrons, first, it is judged whether the energy is greater than the energy threshold. For each secondary electron, it is judged whether its energy is greater than a preset energy threshold. Only secondary electrons with energy greater than the threshold will perform subsequent conversion coefficient calculations. Otherwise, their energy is deposited in place, and their contribution to the dose is included in the restricted stopping power of the primary particles. Secondly, the conversion coefficient is calculated. For secondary electrons with energy greater than the threshold, according to the atomic number, mass number, density, average ionization energy of the target organ and water, and the energy of the secondary electrons, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water is calculated. Through the above steps, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water can be obtained. This conversion coefficient takes into account the energy of secondary electrons and the physical properties of the target organ and water to ensure the accuracy and reliability of the conversion process. In this way, the dose in the target organ can be converted into the dose in water, thus realizing the conversion of tissue dose to water dose. The advantage of doing this is that by reasonably judging the energy threshold and calculating the conversion coefficient, the dose deposition of secondary electrons can be accurately converted, providing reliable data support for precise radiotherapy planning.

[0044] In some possible implementation manners, the conversion relationship is used to indicate the conversion coefficient of the dose deposition of the secondary fragment between the target organ and water;

[0045] The process of obtaining the conversion coefficient of the dose deposition of the secondary fragment between the target organ and water includes:

[0046] Obtain a nuclear reaction information set, where the nuclear reaction information set includes: the target organ dose information deposited in place when the primary particle undergoes a nuclear reaction in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles;

[0047] According to the nuclear reaction information set, calculate the target organ dose information and water dose information of the secondary fragment;

[0048] According to the target organ dose information and water dose information of the secondary fragment, calculate the conversion coefficient of the dose deposition of the secondary fragment between the target organ and water;

[0049] Among them, the process of obtaining the conversion coefficient of the dose deposition of the main secondary charged particles generated by the nuclear reaction between the target organ and water includes:

[0050] Calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity, and energy threshold of the main secondary charged particles;

[0051] Calculate the conversion coefficient between the dose deposition of the main secondary charged particles in the target organ and water according to the restricted stopping power values of the main secondary charged particles in the target organ and water, and the densities of the target organ and water.

[0052] The beneficial effects of this technical solution are as follows: The conversion relationship is used to indicate the conversion coefficient between the dose deposition of secondary fragments in the target organ and water. First, obtain the nuclear reaction information set, and collect information about nuclear reactions, including the target organ dose information when primary particles undergo nuclear reactions in the target organ, the main secondary charged particles and their corresponding target organ dose information and conversion coefficients, and the target organ dose information of other secondary charged particles. Secondly, calculate the target organ dose information and the dose information in water. According to the nuclear reaction information set, calculate the dose deposition of secondary fragments in the target organ and water. This includes calculating the dose of secondary fragments in the target organ and the dose in water to ensure accurate capture of the dose conversion process. After that, calculate the conversion coefficient. According to the dose information of secondary fragments in the target organ and water, calculate the conversion coefficient between the dose deposition of secondary fragments in the target organ and water.

[0053] For the conversion coefficient between the dose deposition of the main secondary charged particles in the target organ and water (i.e., the conversion coefficient corresponding to the main secondary charged particles generated by nuclear reactions), first, calculate the restricted stopping power values. According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity, and energy threshold of the main secondary charged particles, calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively. The restricted stopping power value reflects the degree of energy loss when the particle interacts with the atoms of the substance in different media. Secondly, calculate the conversion coefficient. According to the restricted stopping power values of the main secondary charged particles in the target organ and water and the densities of the target organ and water, calculate the conversion coefficient between the dose deposition of the main secondary charged particles in the target organ and water. In this way, the dose deposition of the main secondary charged particles can be accurately converted. Through the above steps, the conversion coefficient between the dose deposition of secondary fragments in the target organ and water can be obtained. The advantage of doing this is that by obtaining the nuclear reaction information set and calculating the conversion coefficient, the dose distribution of secondary fragments in the target organ and water can be accurately estimated, providing important data support for the design and evaluation of radiotherapy plans.

[0054] In a second aspect, the present application provides an electronic device, which includes a memory and at least one processor. The memory stores a computer program, and the at least one processor is configured to perform the following steps when executing the computer program:

[0055] Obtain the first material dose information of the particle;

[0056] Obtain the conversion relationship between the dose deposition of the particle between the first material and the second material;

[0057] According to the conversion relationship, convert the first material dose information of the particle into the second material dose information.

[0058] In a third aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by at least one processor, it implements the steps of any one of the above methods or realizes the functions of any one of the above electronic devices.

[0059] In a fourth aspect, the present application provides a computer program product, which includes a computer program. When the computer program is executed by at least one processor, it implements the steps of any one of the above methods or realizes the functions of any one of the above electronic devices.

[0060] In a fifth aspect, the present application provides a radiotherapy system, including:

[0061] A mapping device, configured to obtain the CT data of the patient; according to the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from the CT data to the real human body;

[0062] A device for simulating particle transport, configured to simulate the transport process of particles in the target organ of the real human body and calculate the target organ dose information of the particles after the transport process;

[0063] A dose conversion device, configured to convert the target organ dose information of the particle into water dose information by using any one of the above dose conversion methods;

[0064] A device for determining the human body dose, configured to determine the dose used in radiotherapy according to the desired dose information after the water dose information of the particle matches the desired dose information.

[0065] A radiotherapy system is a medical device used to treat diseases such as cancer. The core of the radiotherapy system is to ensure that the dose distribution of particles in the patient's body conforms to the desired dose information set in the treatment plan. However, due to the characteristics of different tissues and media and the complexity of dose conversion, it is often difficult for the prior art to achieve accurate dose distribution.

[0066] The beneficial effects of this technical solution are as follows: A radiotherapy system is provided, aiming to provide precise dose distribution and adjustment functions. The mapping device is used to obtain the CT data of the patient and map the CT value of each voxel to the corresponding real human organ material. By corresponding the CT data with the human anatomical structure, the mapping from CT data to the real human body is realized, thus providing accurate anatomical information. The device for simulating particle transport is used to simulate the transport process of particles in the target organ of the real human body and calculate the dose information of the target organ after the particle transport process. Through the simulation calculation of particle transport, the movement and dose deposition of particles in different tissues can be understood, providing important dose information. The dose conversion device adopts one of the above-provided dose conversion methods to convert the dose information of particles in the target organ into the dose information in water. Through the conversion device, accurate conversion of doses between different media can be achieved, providing more comprehensive information for dose assessment. The device for determining the human dose is used to match the dose information of particles in water with the desired dose information and determine the dose used in radiotherapy according to the required treatment dose. By matching the dose in water and the desired dose, the radiotherapy plan can be adjusted to meet specific treatment needs. This radiotherapy system has the ability to accurately calculate and adjust the dose distribution, which helps to improve the precision and safety of radiotherapy, can provide support for doctors to formulate personalized treatment plans, improve the treatment effect and reduce the occurrence of side effects. Description of the Drawings

[0067] The present application will be further described below in conjunction with the drawings in the specification and the specific embodiments.

[0068] Figure 1 It is a schematic flowchart of a dose conversion method provided by an embodiment of the present application.

[0069] Figure 2 It is a conversion flowchart of the organ dose of a particle to the dose in water provided by an embodiment of the present application.

[0070] Figure 3 It is a structural block diagram of an electronic device provided by an embodiment of the present application.

[0071] Figure 4 It is a schematic structural diagram of a computer program product provided by an embodiment of the present application. Specific Embodiments

[0072] The technical solutions in the present application will be described below in conjunction with the drawings in the specification of the present application and the specific embodiments. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined with each other to form new embodiments.

[0073] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0074] In the embodiments of the present application, the first, second, etc. descriptions that appear are only for the purpose of indicating and distinguishing the described objects, without any order, nor do they represent special limitations on the quantity in the embodiments of the present application, and cannot constitute any limitation to the embodiments of the present application.

[0075] The technical field and related terms of the embodiments of the present application are briefly described below.

[0076] Proton therapy is a radiotherapy technique that uses high-energy proton beams to precisely treat tumors. Compared with traditional X-ray radiotherapy, proton therapy has better physical dose distribution and higher biological effects, thereby reducing damage to normal tissues and improving clinical treatment effects.

[0077] The principle of proton therapy is to utilize the physical properties of protons. That is, after entering the human body, the proton beam will reach the maximum dose (Bragg peak) at a certain depth, and then rapidly decrease until it stops. This property enables the proton beam to release the maximum dose within the tumor while reducing the dose deposition in the normal tissues surrounding the tumor, thereby reducing the side effects caused by the treatment. Proton therapy is applicable to various types of tumors, including pediatric tumors, cranial tumors, head and neck tumors, thoracic tumors, abdominal tumors, bone and soft tissue tumors, etc. Proton therapy is particularly suitable for tumors around critical organs or sensitive to radiation. Proton therapy can better protect normal tissues and organs compared with traditional radiotherapy, reducing the side effects caused by the treatment. Especially for pediatric patients, proton therapy can reduce long-term treatment sequelae and the risk of secondary tumors. Some studies have shown that proton therapy can provide treatment effects comparable to traditional radiotherapy in some cases while reducing adverse reactions.

[0078] The accurate calculation of dose distribution is the prerequisite and guarantee for the implementation of proton therapy. In radiotherapy, first, it is necessary to formulate corresponding treatment plans and schemes based on the tumor location information of the patient. The most crucial among them is to calculate the dose distribution of particles in the patient's body.

[0079] The Monte Carlo (MC) method is regarded as the gold standard for particle dose calculation. Compared with traditional analytical algorithms, it has advantages such as high calculation accuracy. In clinical radiotherapy, when MC calculates the dose deposition of particles in the regions of interest (ROIs) in the human body, it will replace each voxel on the CT image with the corresponding real human organ material according to information such as the treatment site and CT value, so as to realize the mapping from the virtual image to the real human body, and transport and simulate the particles in the human tissue. Due to having real material properties, for the transport and simulation of particles by MC, the interactions of particles are considered to occur in human tissue, and the dose deposition generated belongs to the organ (human tissue) dose. In this application, tissue refers to organ tissue, and tissue dose and organ dose represent the same concept.

[0080] Another dose calculation method corresponding to MC is the analytical algorithm. Due to the differences in algorithm properties, when the analytical algorithm performs dose calculation, it directly replaces the voxels on the CT image with water of different densities, and the density value is determined by the CT value at the corresponding position. Therefore, the dose calculated by it is considered to be the dose in water. The analytical algorithm has high calculation efficiency and low requirements for computer hardware, and is currently the most widely used and common algorithm in dose calculation.

[0081] Due to historical reasons (such as the analytical algorithm being the earliest method used for clinical dose calculation; the clinical basic data were all collected in water), it is customary in clinical treatment to express the ROI dose as the dose in water. Therefore, for the convenience of comparison verification and unified representation, in many cases, the dose calculation results of MC need to be converted, that is, the dose in tissue is converted to the dose in water.

[0082] Regarding the conversion of the proton tissue dose deposition calculated by MC to the corresponding water dose deposition, many scholars have conducted research and proposed different conversion methods. (Reference information: Paganetti H. Dose to water versus dose to medium in proton beam threapy. Physics in medicine and biology. 2009;54:4399-4421; Palmans H, Verhaegen F. Assigning nonoelastic nuclear interactions cross sections to Hounsfield units for Monte Carlo treatment planning of proton beams. Physics in medicine and biology. 2005;50:991-1000) Generally speaking, these methods all have certain limitations or irrationalities, and most of them remain at the research level and are difficult to be truly applied to the MC clinical dose calculation conversion. The specific summary is as follows:

[0083] 1. Approximating the energy loss process of proton ionization interaction as unconstrained energy loss. When MC simulates the energy loss of proton ionization, due to the setting of parameters such as the secondary product threshold and energy cutoff, and the constraint of the energy range that can be simulated by the physical model, this process essentially belongs to constrained energy loss in terms of physical nature. In the existing conversion methods, this process is basically approximated as unconstrained energy loss. This is different from the basic principle of physics and is not rigorous enough;

[0084] 2. Ignoring the conversion of the dose deposition of secondary electrons. Protons and the charged nuclear fragments they produce interact with matter to generate electrons. Although most electrons have low energy and short ranges, there are still some electrons with ranges comparable to the CT voxel size. The simulation results show that 230 MeV protons will produce electrons with ranges greater than 2 mm in water. If the energy of all electrons is deposited in place, it will cause certain errors and impacts on the results, which is not conducive to the realization of precise radiotherapy;

[0085] 3. The conversion of nuclear reaction dose deposition is either too lengthy or too simplistic. The types and yields of secondary fragments generated by the nuclear reaction of protons with matter are directly related to the reaction cross-section and physical model. Due to the imperfection of theoretical models, many model parameters are based on empirical models, and there are significant differences in results among different models. In addition, among the nuclear fragments generated by protons, most are their isotopes, while the yields of heavy nuclei such as α and He-3 are relatively low. Therefore, when dealing with the dose conversion of this process and its subsequent particles, it is not possible to simply deposit their energy in situ or perform dose conversion on all particles, which would affect the calculation efficiency;

[0086] 4. The materials considered are too single. The conversion coefficient from organ dose to water dose is directly related to the material composition. In current research, materials are only classified according to density, and the types of materials are limited, unable to fully cover all organ tissues in the human body. The ICRP Publication 145 divides the organs of the reference person into more than 50 types of materials (Reference information: ICRP Publication 145. ADULT MESH-TYPE REFERENCE COMPUTATIONAL PHANTOMS. 2019). Data shows that organs with different elemental compositions in different parts of the body may have the same density, such as the brain and the bladder wall. Therefore, establishing conversion coefficients for different organs in different parts of the human body has important clinical practical value.

[0087] For example, the currently clinically applied particle arc radiotherapy plan has the following defects:

[0088] 1. The differences in dose deposition conversion coefficients among organs in different parts of the human body and their dependence on tissue parts and organs are not fully considered;

[0089] 2. The unconstrained stopping power is used for the dose deposition conversion of primary particle ionization interactions, which is different from the basic principles and rationality of physics;

[0090] 3. The influence of secondary electrons is ignored, causing their energy to be deposited in situ;

[0091] 4. The conversion of energy deposition occurring during the nuclear reaction and the subsequent energy deposition of the secondary charged particles generated is either too simple or too complex, and the conversion process is not precise enough.

[0092] The present application provides an accurate conversion method for converting the particle dose deposition from an organ (or human tissue) to water based on the energy and type information of incident particles and in combination with the physical processes of their interaction with matter. Based on the reference human information provided by ICRP, fully considering factors such as gender and location, typical tissue organs are selected. According to the physical properties of the organs and the determined conversion method, a conversion coefficient table or a conversion coefficient model applicable to algorithms such as Monte Carlo (MC) is generated, so as to achieve a fast and accurate conversion of the organ dose (or tissue dose) obtained by the MC algorithm to the water dose.

[0093] Regarding the conversion of the heavy ion (α and carbon ion) organ dose calculated by MC to the water dose, there is currently no relevant report, but the physical processes of their energy deposition during the interaction with matter are the same as those of protons. Therefore, the dose conversion method established in the present application is also applicable to heavy ions.

[0094] In addition to the radiotherapy scenario, the dose conversion method of the present application is also applicable to the space radiation dose scenario.

[0095] Based on this, the present application provides a dose conversion method, an electronic device, a computer-readable storage medium, a computer program product, and a radiotherapy system to improve the related technologies.

[0096] The solution provided by the embodiments of the present application involves technologies such as radiotherapy, space radiation, and simulation. It will be specifically described through the following embodiments. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments.

[0097] (Dose Conversion Method)

[0098] See Figure 1 , Figure 1 which is a schematic flowchart of a dose conversion method provided by an embodiment of the present application.

[0099] The embodiments of the present application provide a dose conversion method, and the method includes:

[0100] Step S101: Obtain the first material dose information of the particle;

[0101] Step S102: Obtain the conversion relationship between the dose deposition of the particle between the first material and the second material;

[0102] Step S103: Convert the first material dose information of the particle into the second material dose information according to the conversion relationship.

[0103] In radiotherapy, the particle refers to a charged ion or atomic nucleus, such as a proton, a carbon ion, etc. These particles are used to transfer energy and produce a dose effect.

[0104] In the embodiments of the present application, the first material and the second material can each be any material, but the first material and the second material are two different materials.

[0105] The first material dose information of the particle, that is, the dose deposition (information) of the particle in the first material, refers to the dose distribution of the particle in the first material. The first material can be, for example, an organ, tissue, or other material of a patient.

[0106] The second material dose information of the particle, that is, the dose deposition (information) of the particle in the second material, refers to the dose distribution of the particle in the second material. The second material can be, for example, water.

[0107] The conversion relationship represents the dose conversion relationship between the first material and the second material of the particle. The conversion relationship can be represented by a conversion coefficient table or a conversion coefficient model, and is used to convert the dose information of the first material into the dose information of the second material.

[0108] As an example, in the field of radiotherapy, it is assumed that first, the dose deposition of protons in the organ of a patient is obtained, that is, the first material dose information. Then, the conversion relationship between the organ and water for protons needs to be obtained in order to convert the organ dose information into the dose information in water. This conversion relationship can be obtained through experimental measurement, calculation, model training, etc. Finally, according to the conversion relationship, the organ dose information of protons can be converted into the dose information in water, that is, the second material dose information. In this way, the dose distribution of protons in water can be obtained, providing an accurate reference for radiotherapy planning and dose assessment.

[0109] Space radiation dose refers to the radiation dose received by astronauts in space. Space radiation is different from the radiation on Earth. It includes particles trapped by the Earth's magnetic field, particles emitted into space during solar flares, and high-energy protons and heavy ions from outside the solar system. The space radiation dose value of astronauts is controlled within 0.45 Sv, and an aluminum shielding thickness of 50 g / cm 2 is required. As the mass shielding thickness increases, the contribution of secondary radiation dose generated by the interaction of primary space radiation with the shielding material also gradually increases. (See the article "Active Protection Methods for Space Radiation in Manned Spaceflight" in Space Medicine & Medical Engineering published in June 2012, article number: 1002 - 0837.2012.03.017) In deep space exploration, heavy ions in GCR and protons in SPE are the main shielding objects to be considered. The equivalent dose rate of GCR radiation suffered by astronauts per day is about 1 mSv. During SPE events, high-flux high-energy protons last for several hours or days, with a flux of about 10 10 cm -2.(See the article "Monte Carlo Simulation of Space Radiation Environment and Human Dose" published in "High Power Laser and Particle Beams" in December 2012, article number: 1001 - 4322(2012)12 - 3028 - 05). Among them, SPE is the abbreviation of Solar Particle Events, that is, solar particle events; GCR is the abbreviation of Galactic Cosmic Rays, that is, galactic cosmic rays. Solar particle events refer to the high - energy particle fluxes ejected from the solar active regions during solar eruptions. These particles are mainly protons, and also include other types of particles. Galactic cosmic rays refer to the high - energy particles from the Milky Way outside the solar system. These particles are mainly protons (accounting for 89%), and also include helium nuclei (accounting for 10%) and heavier nuclei (accounting for 1%), up to uranium nuclei.)

[0110] As another example, in the field of space radiation dose, first, obtain the first material dose information of the particles. For example, the MC (i.e., Monte Carlo algorithm) can be used to calculate the dose deposition of (protons, heavy charged) particles in the universe in the astronaut, spacecraft component Si material (the first material). Secondly, obtain the conversion relationship between the dose deposition of the particles between the first material and the second material. For example, the conversion coefficient of the dose deposition of the particles in the universe between the astronaut, Si material and water (the second material) can be obtained through experiments or theoretical calculations. Finally, according to the conversion relationship, convert the first material dose information of the particles into the second material dose information. For example, according to the conversion coefficient of the dose deposition of the particles in the universe between the astronaut, spacecraft device Si and water, convert the dose deposition of the particles in the universe in the astronaut, spacecraft device Si into the dose deposition in water. Among them, the particles in the universe mainly include galactic cosmic rays and solar particle events. Si is silicon.)

[0111] Thus, by considering the conversion relationship of the dose deposition of the particles, the dose information of the particles in different materials can be converted quickly and accurately. This conversion method has important application value in (proton, heavy ion, etc.) radiotherapy and other radiation dose scenarios (such as the field of space radiation dose, etc.), and can realize the comparison and analysis of particle doses in different tissues and media. By converting the first material dose of the particles into the second material dose, effective dose comparison and data analysis can be carried out between different materials and tissues, providing technical support for the optimization and personalization of particle therapy and other radiation dose scenarios.)

[0112] In some embodiments, the conversion relationship is represented by a conversion coefficient table. In the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient, or, each type of particle corresponds to a conversion coefficient; or,

[0113] the conversion relationship is represented by a conversion coefficient model.)

[0114] A conversion relationship refers to a relationship or method used to convert the first material dose information of a particle into the second material dose information. The conversion relationship can be represented in the following possible ways:

[0115] 1. Conversion coefficient table: The conversion coefficient table represents the conversion relationship of dose deposition between the first material and the second material in tabular form. In the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient (from the first material dose to the second material dose), or, each type of particle corresponds to a conversion coefficient. The conversion coefficient is a parameter representing the dose deposition conversion relationship between different materials for a particle. For example, for the combination of protons and different energies, the corresponding conversion coefficients are listed in the conversion coefficient table. By looking up the corresponding conversion coefficient in the table, the dose information of the first material can be converted into the dose information of the second material. For example, in radiotherapy, conversion coefficients can be used to convert the dose deposition of protons in an organ (i.e., organ dose) into the dose deposition in water (i.e., water dose).

[0116] 2. Conversion coefficient model: The conversion coefficient model is a mathematical or physical model used to describe the conversion relationship of the dose of a particle between different materials. This model is established based on factors such as the physical characteristics of the particle, material properties, and interaction mechanisms. Through the conversion coefficient model, the conversion coefficient can be calculated according to the particle type and specific physical parameters, thereby realizing the conversion of the first material dose information to the second material dose information. For example, a conversion coefficient model can be established based on the theoretical energy loss calculation formula of a particle in different materials.

[0117] 3. Conversion matrix. The conversion matrix can be a linear matrix or a non-linear matrix.

[0118] 4. Machine learning model, deep learning model, or reinforcement learning model, etc.

[0119] For example, assume that the conversion relationship is represented by a conversion coefficient table. Create a conversion coefficient table. In the conversion coefficient table, for an organ such as the lung, for each combination of protons (a type of particle) and different energies, provide the corresponding conversion coefficient. For example, for protons with an energy of 100 MeV, there is a specific value in the table for the conversion coefficient from the lung (organ) to water. When it is necessary to convert the dose information of protons in the lung into the dose information in water, it can be calculated by looking up the table and using the corresponding conversion coefficient.

[0120] Another possible implementation is to adopt a conversion coefficient model. A conversion coefficient model can be established based on the energy, charge, velocity of protons, and physical parameters of different materials, such as density, ionization energy, etc., to describe the dose conversion relationship between protons in different materials. Through this conversion coefficient model, the conversion coefficient can be calculated according to the given input information, and then the dose conversion can be achieved. That is to say, for the conversion coefficient model, the input information is information such as organ type, particle type, particle energy, etc., and the output information is the conversion coefficient.

[0121] Therefore, a conversion coefficient table or a conversion coefficient model can be used to represent the conversion relationship. For the implementation method of the conversion coefficient table, a corresponding conversion coefficient can be set for each combination of particle type and particle energy, or a conversion coefficient can be set for each type of particle. In addition, a conversion coefficient model can also be used to represent the conversion relationship.

[0122] The method of using a conversion coefficient table can provide a more direct and simple conversion process. By pre-calculating and recording the conversion coefficients under different particle and energy combinations, the corresponding conversion coefficient can be directly looked up according to the given particle and energy information, and the dose information can be converted.

[0123] The method of using a conversion coefficient model describes the dose conversion relationship of particles by establishing a model. For example, the model parameters are determined through experimental data or theoretical derivation, as well as physical processes such as energy loss and interaction of particles in different materials. It is also possible to use methods such as machine learning and deep learning to train the initial model with a training set to obtain a conversion coefficient model. According to the established model, the corresponding conversion coefficient can be calculated by inputting information such as particles and energy.

[0124] The method of using a conversion coefficient table or a conversion coefficient model to implement the conversion relationship has flexibility and adaptability. The conversion coefficient table can provide direct conversion results and is suitable for simple dose conversion requirements. The conversion coefficient model, on the other hand, can more accurately describe the dose conversion relationship and is suitable for complex scenarios (such as more parameters, higher-dimensional non-linear models) and higher precision requirements.

[0125] In some embodiments, the particle includes one or more of primary particles, secondary electrons, and secondary fragments; or,

[0126] the particle is a proton and / or a heavy ion; or,

[0127] the particle is any charged particle.

[0128] Thus, the particles may include one or more of primary particles, secondary electrons, and secondary fragments. The primary particles are the initially incident charged particles (i.e., the particles directly generated by the radiation source), which mainly lose energy through ionization interactions with matter; the secondary electrons originate from the ionization interactions of primary particles, secondary fragments with matter, and lose energy through ionization interactions with matter; the secondary fragments are generated by nuclear reactions of primary particles with matter, among which the charged nuclear fragments (such as H-2, H-3, He-3, etc.) lose energy through ionization interactions, and the uncharged fragments such as neutrons mainly lose energy through elastic and inelastic collisions with matter.

[0129] In addition, the particles may be protons and / or heavy ions. Protons are one of the most common particles and are widely used in radiotherapy in the medical field. Heavy ions include alpha particles, carbon ions, O-16, Ne-20, Fe-56, etc., which have higher mass and energy and can produce more complex interaction and energy deposition patterns in tissues.

[0130] Alternatively, the particles may also be any kind of charged particles. Charged particles include protons, heavy ions, and other charged particles such as helium ions, lithium ions, etc. The energy loss, the probability of nuclear reactions, and the types and energies of secondary fragments generated by nuclear reactions of these charged particles in different materials are different, so corresponding dose conversions need to be carried out for different particle types.

[0131] By considering the dose conversion relationships of different particles such as primary particles, secondary electrons, and secondary fragments, as well as the conversion requirements for protons, heavy ions, and other charged particles, this dose conversion method can achieve more comprehensive and extensive particle dose conversion, which is of great significance for the dose calculation and evaluation of particle therapy, can meet the dose conversion requirements under different particles and different treatment scenarios, and improve the accuracy and personalization level of radiotherapy.

[0132] In some embodiments, the first material dose information is the target organ dose information, and the second material dose information is the dose information in water;

[0133] The process of obtaining the first material dose information of the particles includes:

[0134] Obtain the medical image data of the patient;

[0135] According to the corresponding values of each statistical unit in the medical image data, replace each statistical unit with the corresponding real human organ material to achieve the mapping from medical image data to the real human body;

[0136] Simulate the transport process of the particles in the target organ of the real human body and calculate the target organ dose information after the transport process of the particles.

[0137] In the embodiments of the present application, the medical image data may include, for example, CT data, X-ray data, PET-CT data, etc. Correspondingly, the medical scanning devices used may be, for example, CT devices, X-ray devices, PET-CT devices, etc. Among them, CT (Computed Tomography) is the electronic computer tomography, and PET (Positron Emission Tomography) is the positron emission tomography. The medical image data of the patient may be the whole-body medical image data or the medical image data of a local part of the human body.

[0138] As an example, when the medical image data is CT data, the statistical unit may be a voxel, and the corresponding value of each voxel in the CT data refers to the CT value corresponding to each voxel in the CT data.

[0139] Voxel is the abbreviation of volume element, which is the smallest unit in three-dimensional space. It is similar to the pixel in a two-dimensional image but has three-dimensional attributes. In CT scanning, each voxel represents a small cube in three-dimensional space, and its size depends on the size of the image matrix, the field of view, the slice thickness, etc. The CT value of the voxel represents the density or other attributes of the substance in the cube.

[0140] In some embodiments, the first material dose information is the target organ dose information, and the second material dose information is the dose information in water;

[0141] The process of obtaining the first material dose information of the particle includes:

[0142] Obtain the CT data of the patient;

[0143] According to the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from the CT data to the real human body;

[0144] Simulate the transport process of the particle in the target organ of the real human body, and calculate the target organ dose information after the particle undergoes the transport process.

[0145] In some embodiments, the step of replacing each voxel with the corresponding real human organ material according to the CT value of each voxel in the CT data to realize the mapping from the CT data to the real human body includes:

[0146] According to the organ basic database, the personal information of the patient, and the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from the CT data to the real human body.

[0147] Among them, the personal information of the patient includes one or more of the patient's gender information, age information, disease type, and medical history information.

[0148] Among them, the acquisition process of the organ basic database includes: screening and classifying various organs of the human body according to the reference person information to generate the organ basic database.

[0149] CT data is medical imaging data obtained by computed tomography (CT scan). CT scan uses X-rays or other radiation sources to scan the patient in different directions, and then generates a three-dimensional image with voxels (volume pixels) through computational reconstruction techniques. CT data provides detailed information on the internal structure and tissue density of the human body.

[0150] Real human organ materials refer to the organ tissue components (or the elemental components of the organs) that actually exist in the human body. For example, in radiotherapy, real human organ materials can be used to simulate the situation inside the patient's body.

[0151] The target organ refers to the organ that needs to receive radiotherapy, and it can be any organ. For example, in the treatment of lung cancer, the lung is the target organ. The target organ can be any of the following organs: brain, cerebellum, brainstem, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, lung, heart, liver, gallbladder, pancreas, spleen, kidney, adrenal gland, ureter, bladder, urethra, esophagus, stomach, duodenum, jejunum, ileum, colon (including cecum, ascending colon, transverse colon, descending colon, and sigmoid colon), rectum, and anus.

[0152] The transport process refers to the process of particles propagating in a substance. In radiotherapy, the transport process of particles in the target organ inside the patient's body can be simulated to calculate the dose deposition in the target organ after the particles complete the transport.

[0153] In some embodiments, the reference person information includes one or more of the reference person's gender information, location information, and age information.

[0154] The reference person can be, for example, the ICRP reference person or the reference person of a specific country or region. ICRP is the abbreviation of the International Commission on Radiological Protection. The ICRP reference person is a standard human model defined by the International Commission on Radiological Protection and is used as a reference object in radiation protection calculations. The ICRP reference person was initially defined as a male aged 20 - 30 years, weighing 70 kg, with a height of 170 cm, living in a climate with an average temperature of 10 - 20 degrees Celsius. However, over time, the ICRP has expanded this definition to include reference persons of different ages and genders. Currently, the ICRP provides a series of data on reference persons, including both males and females, with each gender including newborns, 1-year-olds, 5-year-olds, 10-year-olds, 15-year-olds, and adults.

[0155] Among them, the gender information includes male and female. The human body consists of many different parts, including the head, neck, trunk, limbs, etc. The trunk includes the chest, abdomen, and back. The limbs include the upper limbs and the lower limbs. The upper limbs include the shoulders, upper arms, forearms, wrists, and hands. The lower limbs include the hips, thighs, calves, ankles, and feet. Each part includes one or more organs, and each organ includes multiple (human) tissues.

[0156] In some embodiments, the organ-based database can be an organ-based database based on gender and part. In other embodiments, the organ-based database can be an organ-based database based on gender, part, and age.

[0157] The organ-based database is a database that collects and organizes the basic information and characteristic information of different human organs. This database screens, classifies, and describes various organs of the human body according to the information of the reference person, and provides reference information for organ replacement during the dose conversion process. These organ information can include the type of organ, elemental composition, shape, volume, density, and other specific physical parameters. The elemental composition, or elemental constitution, is used to indicate the type of elements and the proportion (or number of components) of each element.

[0158] As an example, first obtain the CT data of the patient, which provides the density distribution of different regions in the patient's body. Then, map the CT data to the anatomical structure of the real human body by replacing each CT data voxel with the corresponding real human organ material. For example, for the liver CT data of the patient, replace the voxels with a certain CT value with liver tissue material with the corresponding density. Next, by simulating the transport process of particles in the target organ of the real human body, the target organ dose information after the particle transport process can be calculated. The target organ can be the organ where the tumor region is located or other specific organs that need treatment. In this way, the first material dose information of the particle in the target organ can be converted into the second material dose information in water according to the conversion relationship, providing an accurate data basis for dose calculation and evaluation in radiotherapy.

[0159] The above embodiment provides a process of mapping CT data through an organ-based database and patient personal information. The organ-based database records the basic information and characteristics of different organs, such as organ information like elemental composition, shape, volume, and density. According to the patient's personal information such as gender, age, disease type, and medical history, query the corresponding organ information from the organ-based database, and then based on the queried organ information, replace the voxels in the CT data with the corresponding real human organ material, thereby realizing the mapping from CT data to the real human body.

[0160] Thus, the first material dose information can be the dose information of the target organ, and the second material dose information can be the dose information in water. The target organ can be any kind of organ, that is, for each organ, the transport simulation and dose calculation can be performed separately. Specifically, the transport process of particles in each organ can be simulated separately to obtain the organ dose information corresponding to each organ. Moreover, this method can consider the physical process of particle-material interaction and the energy deposition mode, and set different conversion coefficients for different particles, which has high scientificity and accuracy. This dose conversion method is of great significance for accurate dose calculation and radiotherapy planning, and can provide more reliable dose evaluation and treatment effect prediction for clinical practice. Therefore, this dose conversion method has broad application prospects in the field of clinical radiotherapy.

[0161] To obtain the target organ dose information of particles, first, the CT data of the patient can be acquired by performing a CT scan on the patient to obtain the tomographic image data of the patient's body. These data can provide density information about different tissues and organs, which is used for subsequent dose calculation and conversion processes. Secondly, tissue material substitution is performed based on the CT data. According to the CT value of each voxel in the CT image, each voxel is replaced with the corresponding real human organ material. This can achieve the mapping from the virtual image to the real human body, providing specific tissue material properties for subsequent particle transport and dose calculation. After that, the first material dose information of the particles is obtained. By simulating the transport process of one or more particles in the target organ of the real human body, the dose information of each particle in the target organ after the transport process can be calculated (the dose information is the dose deposition information, or the dose distribution information). This requires considering physical processes such as the interaction between particles and tissue materials, energy deposition, as well as parameters such as the initial energy and angular distribution of the particles. Through the above steps, the dose information of the particles in the target organ can be obtained and converted into the dose information in water in the subsequent conversion process. This can facilitate the comparison and verification and unified representation of dose results, providing accurate data support for the planning and evaluation of particle therapy.

[0162] The advantage of this is that by combining CT data and particle transport simulation, the dose conversion from the medium (target organ) to water is achieved. This can more accurately evaluate the dose deposition of particles in the target organ and convert it into the dose in water to meet the requirement of representing the dose as the dose in water in clinical practice. At the same time, this method considers the properties of tissue materials and the physical processes of particles, improving the accuracy and reliability of dose calculation. Therefore, this dose conversion method is of great significance for the realization of precise radiotherapy and clinical dose calculation.

[0163] In the embodiments of this application, according to the energy deposition modes of particles such as protons and heavy ions interacting with matter, considering the particle types and energy information involved in the interaction process, a specific conversion coefficient table can be generated for each organ.

[0164] As an example, particles and their energy deposition modes are classified into 3 types according to the physical interaction type: (1) primary particles (i.e., primary incident particles), which mainly lose energy by ionizing interaction with matter; (2) secondary electrons, which originate from the ionizing interaction of primary particles, secondary fragments with matter, and lose energy by ionizing interaction with matter; (3) secondary fragments, which are produced by the nuclear reaction of primary particles with matter. Among them, charged nuclear fragments (such as H-2, H-3, He-3, etc.) lose energy by ionizing interaction, and uncharged fragments such as neutrons mainly lose energy by elastic and inelastic collisions with matter.

[0165] In the embodiments of the present application, the conversion relationship can be used to indicate the conversion coefficients between the dose depositions of primary particles, secondary electrons, and secondary fragments in the target organ and water.

[0166] In some embodiments, the method further includes:

[0167] According to the target organ dose information of multiple particles and the conversion coefficient corresponding to each particle, calculate the dose information of multiple particles in water, where the conversion coefficient corresponding to each particle refers to the conversion coefficient between the dose deposition of each particle in the target organ and water.

[0168] As an example, the multiple particles are multiple particles generated in proton therapy, and the dose information of multiple particles in water is the dose information in water corresponding to a proton therapy plan (i.e., a proton radiotherapy plan).

[0169] In some embodiments, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the primary particle in the target organ and water;

[0170] The process of obtaining the conversion coefficient between the dose deposition of the primary particle in the target organ and water includes:

[0171] According to the energy of the primary particle and / or the voxel size of dose statistics, obtain the energy threshold for generating secondary electrons by ionization interaction;

[0172] According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity of the primary particle, and the energy threshold, calculate the restricted stopping power values of the primary particle in the target organ and water respectively;

[0173] According to the restricted stopping power values of the primary particle in the target organ and water, and the densities of the target organ and water, calculate the conversion coefficient between the dose deposition of the primary particle in the target organ and water.

[0174] In some embodiments, the step of calculating the restricted stopping power values of the primary particle in the target organ and water respectively according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity of the primary particle, and the energy threshold, includes:

[0175] According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ, as well as the charge, velocity of the primary particle, and the energy threshold, calculate the restricted stopping power value of the primary particle in the target organ;

[0176] Calculate the restricted stopping power value of the primary particle in water based on the number of atoms per unit mass of water, the effective atomic number, the mean ionization energy, as well as the charge, velocity of the primary particle, and the energy threshold.

[0177] In this embodiment, the primary particle refers to the primary incident particle used in radiotherapy, which can be a proton, a carbon ion, etc.

[0178] The energy threshold refers to the minimum energy required for an ionization interaction to generate secondary electrons. This value depends on one or more of the energy of the primary particle and the size of the dose statistical voxel. The energy of the primary particle can include, for example, the kinetic energy of the primary particle. The size of the dose statistical voxel is the dimension of the dose statistical voxel. Since the generation threshold of secondary electrons is set, only electrons with kinetic energy higher than this threshold will be generated and tracked. For example, the energy threshold can be 10 keV, indicating that only when the energy of the electron is higher than 10 keV will it be generated and tracked. Conversely, the energy of the electron will be deposited locally, and its contribution to the dose is included in the restricted stopping power of the primary particle that generated the electron.

[0179] The number of atoms per unit mass is the number of atoms in the medium per unit mass, which refers to the number of atoms contained in each unit mass of the substance. Its unit is mol / g. For example, the molecular formula of water is H 2 O, and its molar mass is 18 g / mol. Therefore, the number of atoms per unit mass of water is 1 / 18 mol / g. Although human organs are not single-component substances, the corresponding number of atoms per unit mass can be calculated based on the elemental composition of each organ. Similarly, other physical quantities of the organ can be calculated, which will not be elaborated here.

[0180] The effective atomic number refers to the equivalent atomic number exhibited by a substance when interacting with electromagnetic radiation. It depends on the chemical composition of the substance and the energy of the electromagnetic radiation. For example, for low-energy X-rays, the effective atomic number of water is approximately 7.42.

[0181] The mean ionization energy refers to the average energy required to ionize an atom or molecule. Its unit is eV. For example, the mean ionization energy of a water molecule is approximately 78 eV.

[0182] Charge refers to the amount of electric charge carried by an object. Its unit is Coulomb (C). Charge determines the nature of the interaction between a particle and other charged particles or an electric field. For example, an electron carries a negative charge, and its electric charge is -1.6×10 -19 C. For a primary particle, such as a proton, the charge is usually a positive charge (+1.6×10 -19 C).

[0183] Speed refers to how fast an object is moving. Its unit is meters per second (m / s). The speed of primary particles affects the process of their interaction with atoms or molecules in the medium. For example, in proton therapy, protons are accelerated to speeds close to the speed of light. Proton beam therapy uses special machines, such as cyclotrons and synchrotrons, to accelerate protons to about 60% of the speed of light, with an energy of up to 250 million electron volts.

[0184] Density is the ratio of the mass of a medium to its volume, and the unit can be grams per cubic centimeter (g / cm 3 ). It represents the degree of compactness of the medium and the strength of the interaction between molecules. For the target organ and water, their densities are determined according to their physical properties. Taking water as an example, the density is about 1 g / cm 3 .

[0185] The restricted stopping power refers to the total energy loss of protons in the ionization interaction with the medium, excluding the energy of electrons with kinetic energy higher than the energy threshold. For example, in the calculation process, the value of the restricted stopping power is equal to the average energy lost by protons in the ionization interaction with the medium minus the energy of all electrons with kinetic energy greater than the energy threshold generated in the ionization process. This value depends on the charge of the particle, the particle energy, and the energy threshold (for generating secondary electrons), as well as the number of atoms per unit mass, the effective atomic number, and the average ionization energy of the material, etc. For example, for monoenergetic protons with an energy of 100 MeV in water, when the energy threshold is 100 eV, the value of the restricted stopping power is about 0.58 keV / μm; when the energy threshold is 10 eV, the value of the restricted stopping power is about 0.49 keV / μm.

[0186] Thus, the conversion relationship can be used to indicate the conversion coefficient between the dose deposition of primary particles in the target organ and water. To obtain the dose deposition conversion coefficient of primary particles, first, obtain the energy threshold for secondary electrons generated by ionization interactions. For example, the energy threshold for secondary electrons generated by ionization interactions can be determined according to the energy and / or dose of the primary particles and the voxel size of the statistical volume. This threshold is used to screen out secondary electrons with energies higher than the threshold for subsequent dose conversion calculations. Secondly, calculate the restricted stopping power values. According to the number of atoms per unit mass, effective atomic number, and mean ionization energy of the target organ, as well as the number of atoms per unit mass, effective atomic number, and mean ionization energy of water, and the charge, velocity, and energy threshold of the primary particles, calculate the restricted stopping power value of the primary particles in the target organ and the restricted stopping power value of the primary particles in water respectively. The restricted stopping power value is related to the energy of the particle, the composition and properties of the material, etc. After that, calculate the conversion coefficient. According to the restricted stopping power values of the primary particles in the target organ and water, and the density of the target organ and the density of water, calculate the conversion coefficient between the dose deposition of the primary particles in the target organ and water. The conversion coefficient represents the dose conversion relationship from the target organ to water, which converts the dose in the target organ into the corresponding dose in water. Through the above steps, the conversion coefficient between the dose deposition of primary particles in the target organ and water can be obtained. In this way, the dose in the target organ can be converted into the dose in water, realizing the conversion from tissue dose to water dose. The advantage of doing this is that by considering factors such as restricted stopping power, the density of the material, as well as the energy of the particle and the voxel size of the dose statistics, the dose conversion coefficient can be calculated more accurately, improving the accuracy and reliability of dose calculation and providing support for the realization of precise radiotherapy.

[0187] For example, when treating lung cancer, the target organ is the lung. First, according to the energy and dose of the proton and the voxel size of the statistical volume, obtain the energy threshold for secondary electrons generated by ionization interactions. Secondly, according to the number of atoms per unit mass, effective atomic number, and mean ionization energy of the lung and water, and the charge, velocity, and energy threshold of the proton, calculate the restricted stopping power values of the proton in the lung and in water respectively. After that, according to the restricted stopping power values of the proton in the lung and in water, and the densities of the lung and water, calculate the conversion coefficient between the dose deposition of the proton in the lung and water.

[0188] In some other embodiments, the process of obtaining the conversion coefficient between the dose deposition of the primary particles in the target organ and water includes:

[0189] Input the type and energy of the primary particles and the type of the target organ into the conversion coefficient model to obtain the conversion coefficient between the dose deposition of the primary particles in the target organ and water.

[0190] In some embodiments, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water;

[0191] The process of obtaining the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water includes:

[0192] Determine whether the energy of the secondary electrons is greater than the energy threshold;

[0193] When the energy of the secondary electrons is greater than the energy threshold, calculate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water according to the atomic numbers, mass numbers, densities, mean ionization energies of the target organ and water, and the energy of the secondary electrons.

[0194] Since a generation threshold (i.e., energy threshold) of secondary electrons is set, in this embodiment, only secondary electrons with kinetic energy higher than this energy threshold will be generated and traced. Therefore, the correction is only for this part of the electrons, that is, when calculating the dose in water of secondary electrons, for this part of the electrons (with kinetic energy higher than this energy threshold), convert their organ dose to the dose in water.

[0195] The atomic number refers to the serial number of a chemical element in the periodic table of elements. It represents the number of protons in the atomic nucleus and also reflects the electronic structure and chemical properties of the element. When calculating the conversion coefficient of the dose deposition of secondary electrons, the atomic numbers of the target organ and water are used to determine the basic characteristics of the medium.

[0196] The mass number refers to the total number of protons and neutrons in the atomic nucleus. It represents the mass of the atomic nucleus and reflects the relative weight of the medium. When calculating the conversion coefficient of the dose deposition of secondary electrons, the mass numbers of the target organ and water are used to determine the basic characteristics of the medium.

[0197] When calculating the conversion coefficient of the dose deposition of secondary electrons, the densities and mean ionization energies of the target organ and water are used to determine the physical properties of the medium.

[0198] The energy of the secondary electrons is, for example, the kinetic energy of the secondary electrons.

[0199] Thus, the conversion relationship can be used to indicate the conversion coefficient of the dose deposition of secondary electrons between the target organ and water. To obtain the dose deposition conversion coefficient of secondary electrons, first, it is determined whether the energy is greater than the energy threshold. For each secondary electron, it is judged whether its energy is greater than a preset energy threshold. Only secondary electrons with energy greater than the threshold will proceed with subsequent conversion coefficient calculations. Otherwise, their energy is deposited in situ, and their contribution to the dose is included in the restricted stopping power of the primary particles. Secondly, the conversion coefficient is calculated. For secondary electrons with energy greater than the threshold, based on the atomic number, mass number, density, mean ionization energy of the target organ, as well as the atomic number, mass number, density, mean ionization energy of water, and the energy of the secondary electrons, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water is calculated. Through the above steps, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water can be obtained. This conversion coefficient takes into account the energy of secondary electrons and the physical properties of the target organ and water to ensure the accuracy and reliability of the conversion process. In this way, the dose in the target organ can be converted into the dose in water, thus realizing the conversion of tissue dose to water dose. The advantage of this is that by reasonably judging the energy threshold and calculating the conversion coefficient, the dose deposition of secondary electrons can be accurately converted, providing reliable data support for precise radiotherapy planning.

[0200] For example, when treating lung cancer, it is assumed that it is necessary to calculate the dose conversion coefficient of secondary electrons between the lungs (target organ) and water. First, it is determined whether the energy of the secondary electrons is greater than the energy threshold (for example, 10 keV). If the energy of the secondary electrons is greater than the energy threshold, then based on the atomic number, mass number, density, mean ionization energy of the lungs and water, as well as the energy of the secondary electrons, the conversion coefficient of the dose deposition of secondary electrons between the lungs and water is calculated.

[0201] In some other embodiments, the process of obtaining the conversion coefficient of the dose deposition of the secondary electrons between the target organ and water includes:

[0202] Input the energy of the secondary electrons and the type of the target organ into a conversion coefficient model to obtain the conversion coefficient of the dose deposition of the secondary electrons between the target organ and water.

[0203] In some embodiments, the conversion relationship is used to indicate the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water;

[0204] The process of obtaining the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water includes:

[0205] Obtain a set of nuclear reaction information, where the set of nuclear reaction information includes: the target organ dose information deposited in place when the primary particles undergo nuclear reactions in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except for the main secondary charged particles;

[0206] Calculate the target organ dose information and water dose information of the secondary fragments according to the set of nuclear reaction information;

[0207] Calculate the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water according to the target organ dose information and water dose information of the secondary fragments;

[0208] Among them, the process of obtaining the conversion coefficient between the dose deposition of the main secondary charged particles generated by the nuclear reaction in the target organ and water includes:

[0209] Calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, the charge, velocity of the main secondary charged particles, and the energy threshold;

[0210] Calculate the conversion coefficient between the dose deposition of the main secondary charged particles in the target organ and water according to the restricted stopping power values of the main secondary charged particles in the target organ and water and the densities of the target organ and water.

[0211] The set of nuclear reaction information refers to a set containing nuclear reaction information generated when primary particles interact with matter. This information includes the target organ dose information deposited in place when the primary particles undergo nuclear reactions in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except for the main secondary charged particles.

[0212] In some embodiments, the calculating the target organ dose information and water dose information of the secondary fragments according to the set of nuclear reaction information includes:

[0213] Perform a summation calculation on the target organ dose information deposited in place when the primary particles undergo nuclear reactions in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reaction, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except for the main secondary charged particles, and use the result as the target organ dose information of the secondary fragments;

[0214] The sum of the target organ dose information deposited in situ when the primary particles undergo nuclear reactions in the target organ, the product of the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except for the main secondary charged particles is calculated as the water dose information of the secondary fragments.

[0215] It can be seen that when calculating the target organ dose information and water dose information of the secondary fragments corresponding to nuclear reactions, the difference between the two lies in the second term in the summation calculation. The former corresponds to "the target organ dose information of the main secondary charged particles generated by the nuclear reaction", and the latter corresponds to "the product of the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients". Numerically, "the product of the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients" is equal to "the water dose information of the main secondary charged particles generated by the nuclear reaction". That is to say, when calculating the water dose of the secondary fragments, corrections are made for the main secondary charged particles, that is, their organ doses are converted to water doses; for other secondary charged particles, no corrections are made, and their organ doses are directly used as water doses. Through selective and targeted corrections, both the higher calculation efficiency and higher calculation accuracy in the dose conversion process are taken into account.

[0216] Thus, the conversion relationship can be used to indicate the conversion coefficient between the dose deposition of secondary fragments in the target organ and water. First, obtain the nuclear reaction information set, collect information about nuclear reactions, including the target organ dose information deposited in situ when the primary particles undergo nuclear reactions in the target organ, the main secondary charged particles and their corresponding target organ dose information and conversion coefficients, and the target organ dose information of other secondary charged particles. Secondly, calculate the target organ dose information and water dose information. According to the nuclear reaction information set, calculate the dose deposition of secondary fragments in the target organ and water. This includes calculating the dose of secondary fragments in the target organ and in water to ensure accurate capture of the dose conversion process. After that, calculate the conversion coefficient. According to the dose information of secondary fragments in the target organ and water, calculate the conversion coefficient between the dose deposition of secondary fragments in the target organ and water.

[0217] For the conversion coefficient of the dose deposition of the main secondary charged particles between the target organ and water (i.e., the conversion coefficient corresponding to the main secondary charged particles generated by the nuclear reaction), first, calculate the restricted stopping power values. According to the number of atoms per unit mass, effective atomic number, and mean ionization energy of the target organ, as well as the number of atoms per unit mass, effective atomic number, and mean ionization energy of water, and the charge, velocity, and energy threshold of the main secondary charged particles, calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively. The restricted stopping power reflects the degree of energy loss when the particles interact with the atoms of the substance in different media, that is, the magnitude of the energy loss of the particles interacting with different media. Secondly, calculate the conversion coefficient. According to the restricted stopping power values of the main secondary charged particles in the target organ and water and the densities of the target organ and water, calculate the conversion coefficient of the dose deposition of the main secondary charged particles between the target organ and water. In this way, the dose deposition of the main secondary charged particles can be accurately converted. Through the above steps, the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water can be obtained. The advantage of doing this is that by obtaining the nuclear reaction information set and calculating the conversion coefficient, the dose distribution of the secondary fragments in the target organ and water can be accurately estimated, providing important data support for the design and evaluation of radiotherapy plans.

[0218] For example, when treating lung cancer, assume that it is necessary to calculate the dose conversion coefficient of the secondary fragments between the lung (target organ) and water. First, obtain the nuclear reaction information set, including the lung dose information deposited in situ when the primary particles undergo nuclear reactions in the lung, the lung dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the lung dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles. Secondly, according to the nuclear reaction information set, calculate the dose information of the secondary fragments in the lung and water. Then, according to the dose information of the secondary fragments in the lung and water, calculate the conversion coefficient of the secondary fragments between the lung and water.

[0219] In some other embodiments, the process of obtaining the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water includes:

[0220] Input the type and energy of the secondary fragments and the type of the target organ into the conversion coefficient model to obtain the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water.

[0221] In a specific application scenario, the embodiment of the present application also provides a dose conversion method, and the method includes:

[0222] Obtain the CT data of the patient;

[0223] According to the CT value of each voxel in the CT data, each voxel is replaced with the corresponding real human organ material (i.e., the organ element components at the corresponding spatial position of each voxel are set) to achieve the mapping from CT data to the real human body;

[0224] Respectively simulate the transport process of each of the particles corresponding to proton therapy in the target organ of the real human body, and calculate the target organ dose information of each of the particles after the transport process; the particles corresponding to proton therapy include primary particles, secondary electrons, and secondary fragments;

[0225] Obtain the conversion relationship between the dose deposition of each of the particles in the target organ and water; the conversion relationship is represented by a conversion coefficient table, and in the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient;

[0226] According to the conversion relationship, convert the target organ dose information of primary particles, secondary electrons, and secondary fragments into water dose information respectively;

[0227] Sum up the water dose information of primary particles, secondary electrons, and secondary fragments, and calculate the water dose information corresponding to proton therapy.

[0228] Among them, the process of obtaining the conversion coefficient of the dose deposition of the primary particle between the target organ and water includes:

[0229] According to the energy of the primary particle and / or the voxel size of the dose statistics, obtain the energy threshold for the ionization interaction to generate secondary electrons;

[0230] According to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, the charge, velocity of the primary particle, and the energy threshold, calculate the restricted stopping power values of the primary particle in the target organ and water respectively;

[0231] According to the restricted stopping power values of the primary particle in the target organ and water, and the densities of the target organ and water, calculate the conversion coefficient of the dose deposition of the primary particle between the target organ and water.

[0232] Among them, the process of obtaining the conversion coefficient of the dose deposition of the secondary electron between the target organ and water includes:

[0233] Judge whether the energy of the secondary electron is greater than the energy threshold;

[0234] When the energy of the secondary electrons is greater than the energy threshold, a conversion coefficient of the dose deposition of the secondary electrons between the target organ and water is calculated according to the atomic number, mass number, density, mean ionization energy of the target organ and water, and the energy of the secondary electrons.

[0235] Among them, the process of obtaining the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water includes:

[0236] Obtain a nuclear reaction information set, where the nuclear reaction information set includes: the target organ dose information deposited in place when the primary particles undergo nuclear reactions in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reactions and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reactions except the main secondary charged particles;

[0237] According to the nuclear reaction information set, calculate the target organ dose information and the water dose information of the secondary fragments;

[0238] According to the target organ dose information and the water dose information of the secondary fragments, calculate the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water;

[0239] Among them, the process of obtaining the conversion coefficient of the dose deposition of the main secondary charged particles generated by the nuclear reactions between the target organ and water is similar to the process of obtaining the conversion coefficient of the dose deposition of the primary particles between the target organ and water, and specifically includes:

[0240] According to the number of atoms per unit mass, effective atomic number, mean ionization energy of the target organ and water, the charge, velocity of the main secondary charged particles, and the energy threshold, calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively;

[0241] According to the restricted stopping power values of the main secondary charged particles in the target organ and water, and the densities of the target organ and water, calculate the conversion coefficient of the dose deposition of the main secondary charged particles between the target organ and water.

[0242] As an example, assume that it is necessary to implement the conversion from organ dose to water dose.

[0243] First, an organ basic database can be established. For example, based on the ICRP reference person or the Chinese reference person, various organs of the human body are screened and classified according to information such as gender and tissue location to generate an organ basic database based on gender and location.

[0244] Secondly, calculate the conversion coefficients of each type of particle for different organs. Based on the energy deposition modes of interactions between particles such as protons and heavy ions with matter, considering the types of particles and energy information involved in the interaction process, specific conversion coefficients are generated for each organ. For example, considering the particles and their energy deposition modes, according to the type of physical interaction, the particles are divided into three types: primary incident particles, secondary electrons, and secondary fragments.

[0245] The conversion process from organ dose to water dose can be expressed as:

[0246] [D w j =[D m ×S w,m (E)] primary,j +[D m ×S w,m (E)] electron,j +[D m ×S w,m (E)] nuclear,j (1)

[0247] where the subscript j represents the j-th organ, and the subscripts w and m represent water and organ m respectively. D w and D m represent the dose depositions of particles with energy E in water and organ m respectively in different reaction processes. The subscripts primary, electron, and nuclear represent primary particles, secondary electrons, and nuclear reactions respectively.

[0248] The calculation processes of the conversion coefficients corresponding to primary particles, secondary electrons, and secondary fragments are as follows:

[0249] (1) Conversion of the organ dose of primary particles to the water dose. This conversion is based on the Bethe - bloch theoretical formula (Reference: Newhauser WD, Zhang R. The physics of proton therapy. Physics in medicine and biology. 2005; 60: R155 - R209.), and is obtained by calculating the ratio of the electron - restricted stopping powers of primary particles in two materials (organ and water) (i.e., the ratio of their restricted stopping powers).

[0250] The conversion process of the organ dose of primary particles to the water dose can be expressed as:

[0251]

[0252] where: [D w primary and [D m ​​​primary respectively represent the dose depositions of primary particles in water and in organ m (i.e., the water dose and the organ dose of primary particles), ρ w and ρ m respectively represent the densities of water and organ m, and respectively represent the restricted stopping powers of primary particles in water and in organ m, [s w,m (E)] primary represents the conversion coefficient of the dose deposition of primary particles from organ m to water, and its value is related to the kinetic energy E of primary particles, the elemental composition of organ m, and the production threshold Δ of secondary electrons (i.e., ω c , and the two are the same physical quantity).

[0253] Restricted stopping power can be expressed as:

[0254]

[0255] where: r e is the classical electron radius, m e is the electron mass, c is the speed of light in vacuum, in (capital letter) Z is the effective atomic number of the medium, μA is the number of atoms per unit mass of the medium, and "z 2 " in (lowercase letter) z is the charge of the primary incident particle (in units of the unit electron charge). β = c / v, v is the speed of the primary incident particle, I is the average ionization energy of the medium, ω c (i.e., Δ) is the energy threshold for the production of secondary electrons by ionization interactions, and this energy threshold can be comprehensively considered, for example, in terms of factors such as the energy of primary particles and the size of the dose recording voxel.

[0256] (2) Conversion of the organ dose of secondary electrons to the water dose

[0257] Since the energy threshold for the production of secondary electrons is set, only electrons with kinetic energy higher than this threshold will be produced and tracked. Therefore, this dose conversion method corrects only for this part of the electrons for secondary electrons.

[0258] The conversion process of the organ dose of secondary electrons to the water dose can be expressed as:

[0259] [D w electron = [D m × s w,m (E)] electron (4)

[0260]

[0261] where: [D w ​​electron and [D m electron represent the dose depositions of secondary electrons in water and organ m (i.e., the water dose and organ dose of secondary electrons), respectively, [s w,m (E)] electron represents the conversion coefficient of the dose deposition of secondary electrons from organ m to water, which is related to the atomic number Z, mass number A, density ρ, and mean ionization energy I. The subscripts w and m represent the corresponding parameters of water and organ m, respectively. A(E electron ) and B(E electron ) are constants related to electron energy but independent of the medium material, and the values can be obtained from the ICRU Report 37 (Reference information: ICRU Report 37. Stopping Powers for Electrons and Positrons. 1984.).

[0262] (3) Conversion of organ dose to water dose for nuclear reactions (corresponding to secondary fragments)

[0263] When particles such as protons and heavy ions undergo nuclear reactions with matter, the primary particles will be absorbed and secondary fragments will be produced, and energy deposition will occur simultaneously. The types and energy distributions of the fragments produced in this process are relatively complex, including both charged secondary fragments (such as H-2, He-3, etc.) and uncharged neutral particles (γ, n, etc.). In this embodiment, in order to balance calculation efficiency and accuracy, the secondary particles generated by nuclear reactions are first screened, and the secondary particles that contribute more significantly to the calculation results (i.e., the main secondary charged particles) are selected, and only the dose depositions of these particles are converted. For other particles (i.e., other secondary charged particles), the dose in the organ is directly used instead of the dose in water.

[0264] The conversion process of organ dose to water dose for nuclear reactions (corresponding to secondary fragments) can be expressed as:

[0265]

[0266] where: [Dw] Nuclear represents the dose deposition of secondary fragments in water, i.e., the water dose of secondary fragments; [Dm] Nuclear represents the in-situ dose deposition in organ m when the primary particles undergo nuclear reactions; represents the dose deposition of the main secondary charged particles generated by nuclear reactions in organ m (i.e., the organ dose of the main secondary charged particles). These particles mainly lose energy through ionization interactions, and the conversion coefficient is calculated by Equation (2) and will not be elaborated here; ​Denote the dose deposition of secondary charged particles other than those considered for conversion (i.e., other secondary charged particles) generated by nuclear reactions in organ m (i.e., the organ dose of other secondary charged particles), and its dose deposition in water is approximately equal to the dose deposition in organ m (i.e., the water dose of other secondary charged particles is equivalent to the organ dose of other secondary charged particles).

[0267] Combined with the calculation processes of the conversion coefficients corresponding to the primary particles, secondary electrons, and secondary fragments in the above (1)-(3), during MC calculation, first, according to the CT value information of the tissue site, set the organ components (i.e., the elemental components of the organ) at the corresponding spatial positions of each voxel. According to the initial information such as the energy and angular distribution of the primary particles, perform (particle) tracking on them and record the dose deposition of the particles in each organ (i.e., record the organ dose of the particles for each organ). According to information such as the organ type, particle type, physical reaction type between the particle and the organ, and particle energy, look up the corresponding coefficients from the conversion coefficient table of the corresponding organ, and convert the organ dose into the water dose. Among them, the particle tracking process is related to the particle type, kinetic energy information, spatial position, and (physical) reaction type between the particle and the organ.

[0268] See Figure 2 , Figure 2 which is a conversion flow chart of the organ dose of a particle to the water dose provided by an embodiment of the present application.

[0269] As an example, an embodiment of the present application also provides a dose conversion method, including the following steps:

[0270] Import CT data;

[0271] According to the CT value corresponding to each voxel in the organ basic database and the CT data, set the organ element composition corresponding to each voxel; among them, the organ basic database is a database based on information such as gender and location established according to the relevant values of the ICRP reference person, including organ types and information such as the elemental composition and density of each organ;

[0272] Perform particle tracking through the MC algorithm to obtain the organ dose of each particle;

[0273] For each organ O j , query the conversion coefficient corresponding to the combination of particle type and particle energy (i.e., primary particle conversion coefficient, electron conversion coefficient, nuclear reaction conversion coefficient, etc.) from the (organ) conversion coefficient table corresponding to the organ, and convert the organ dose of each particle calculated by the MC algorithm into the water dose;

[0274] Among them, the establishment process of the organ conversion coefficient table includes:

[0275] According to the particle type p i, the particle energy E i , determine the interaction type j between the particle and the organ;

[0276] According to the particle type p i , the particle energy E i and the interaction type j, establish the conversion function F j (p i , E i );

[0277] According to the conversion function, for different combinations of particle types and particle energies, calculate a series of conversion coefficients and establish an organ conversion coefficient table.

[0278] Thereby, converting the organ dose calculated by the Monte Carlo dose algorithm (i.e., the MC algorithm) into the water dose involves the rapid conversion process of the organ dose to the water dose in particle radiotherapy such as proton and heavy ion radiotherapy, and at the same time takes into account the classification and elemental composition of human organs in particle radiotherapy (i.e., particle radiotherapy).

[0279] Through the above dose conversion method, the dose conversion process is made more scientific, reasonable and systematic. First, the dose conversion of primary particles is more reasonable and accurate. Considering the energy threshold of secondary electrons generated during the ionization interaction process, the corresponding stopping power value corresponding to the energy threshold is used to calculate the conversion coefficients of the corresponding particle energy and organ. Secondly, consider the conversion of secondary electron dose deposition. Comprehensively consider the voxel size of dose statistics in clinical treatment, the energy of primary particles, and the range of electrons in different organs, select its reasonable generation threshold (i.e., energy threshold), transport the electrons with energy higher than the generation threshold, and convert the dose deposition on its traversing path. Thirdly, for the nuclear reaction process, according to information such as the types, yields, and contributions to the total dose of secondary fragments generated by the nuclear reaction, screen out the fragment types that have a greater impact on the results (i.e., the main secondary charged particles), and correct their dose depositions; for the fragments that have a less significant impact on the calculation results (i.e., other secondary charged particles), directly use their dose depositions in the organ as the water dose at the corresponding spatial position. In this way, it is targeted, ensuring the calculation efficiency while maintaining the accuracy of the results. That is to say, the dose conversion method can balance high calculation efficiency and high accuracy.

[0280] Moreover, the above dose conversion method makes the establishment of conversion coefficients more accurate, systematic and perfect. For example, fully consider the differences in the elemental composition of human organs with respect to gender and tissue location, use the model data of ICRP reference man or Chinese reference man, and establish a set of systematic conversion coefficients for different organs, different energies and types of particles.

[0281] In addition, the above dose conversion method has strong universality. The above dose conversion method and conversion coefficients can be used not only for the conversion of proton, α, and carbon ion doses from organ dose to water dose in clinical treatment, but also for the conversion of dose deposition of heavy ions such as O-16, Ne-20, Fe-56, etc. from any material to water dose deposition in other studies.

[0282] Moreover, the above dose conversion method is simple and direct. Starting from the basic principle of the interaction between particles and matter, a dose deposition conversion coefficient table corresponding to energy is generated for different particle types and human organ types. During MC calculation, according to information such as particle type, particle energy, and organ type, the corresponding conversion coefficient can be queried from the conversion coefficient table to directly convert the organ dose of the particle into the water dose. For example, in practical applications, for each organ, a conversion coefficient table is established, in which, for each combination of particle and different energies, a corresponding conversion coefficient is set.

[0283] It should be noted that the reference human organ component data in the above dose conversion method can use the corresponding data of ICRP reference human or Chinese reference human; in nuclear reaction conversion, dose conversion can also be performed for all secondary charged particles, not limited to the main secondary charged particles, that is, without distinguishing between the main secondary charged particles and other secondary charged particles, dose conversion from organ dose to water dose is performed for all secondary charged particles; the above dose conversion method can be applied to the conversion of different charged particles from any material dose to water dose; the above dose conversion method can be applied to different radiation dose scenarios, not limited to the field of particle radiotherapy such as protons and heavy ions. For example, the above dose conversion method can be applied to the field of space radiation dose, etc.

[0284] (Radiotherapy system)

[0285] The embodiment of the present application also provides a radiotherapy system, including:

[0286] A mapping device for obtaining CT data of a patient; according to the CT value of each voxel in the CT data, replacing each voxel with the corresponding real human organ material to achieve the mapping from CT data to a real human body;

[0287] A device for simulating particle transport, for simulating the transport process of particles in the target organ of a real human body and calculating the target organ dose information of the particles after the transport process;

[0288] A dose conversion device for converting the target organ dose information of the particles into water dose information by using any of the above dose conversion methods;

[0289] A device for determining a human body dose, which is used to determine the dose used in radiotherapy according to the desired dose information after the dose information of the particles in water matches the desired dose information.

[0290] A radiotherapy system is a medical device used to treat diseases such as cancer. The radiotherapy system needs to ensure that the dose distribution of particles in the patient's body conforms to the desired dose information set in the treatment plan. However, due to the characteristics of different tissues and media and the complexity of dose conversion, it is often difficult to achieve accurate dose allocation in the prior art.

[0291] Therefore, the embodiments of the present application provide a radiotherapy system, aiming to provide precise dose distribution and adjustment functions. The mapping device is used to obtain the CT data of the patient and map the CT value of each voxel to the corresponding real human organ material. By corresponding the CT data with the human anatomical structure, the mapping from CT data to the real human body is realized, thus providing accurate anatomical information. The device for simulating particle transport is used to simulate the transport process of particles in the target organ of the real human body and calculate the dose information of the target organ after the particle transport. Through the simulation calculation of particle transport, the movement and dose deposition of particles in different tissues can be understood, providing important dose information. The dose conversion device adopts one of the above-provided dose conversion methods to convert the dose information of particles in the target organ into the dose information in water. Through the conversion device, accurate conversion of doses between different media can be achieved, providing more comprehensive information for dose evaluation. The device for determining the human body dose is used to match the dose information of particles in water with the desired dose information and determine the dose used in radiotherapy according to the required treatment dose. By matching the dose in water and the desired dose, the radiotherapy plan can be adjusted to meet specific treatment needs. This radiotherapy system has the ability to accurately calculate and adjust the dose distribution, which helps to improve the accuracy and safety of radiotherapy, can support doctors in formulating personalized treatment plans, improve the treatment effect and reduce the occurrence of side effects.

[0292] (Electronic device)

[0293] The embodiments of the present application also provide an electronic device, and its specific embodiments are consistent with the embodiments and the achieved technical effects described in the above method embodiments, and some contents will not be repeated here.

[0294] The electronic device includes a memory and at least one processor. The memory stores a computer program, and the at least one processor is configured to perform the following steps when executing the computer program:

[0295] Obtain the first material dose information of the particles;

[0296] Obtain the conversion relationship between the dose deposition of the particles between the first material and the second material;

[0297] Convert the first material dose information of the particle into second material dose information according to the conversion relationship.

[0298] Convert the first material dose information of the particle into second material dose information according to the conversion relationship.

[0299] In some embodiments, the conversion relationship is represented by a conversion coefficient table. In the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient, or each type of particle corresponds to a conversion coefficient; or,

[0300] The conversion relationship is represented by a conversion coefficient model.

[0301] In some embodiments, the particle includes one or more of primary particles, secondary electrons, and secondary fragments; or,

[0302] The particle is a proton and / or a heavy ion; or,

[0303] The particle is any charged particle.

[0304] In some embodiments, the first material dose information is target organ dose information, and the second material dose information is water dose information;

[0305] The process of obtaining the first material dose information of the particle includes:

[0306] Obtain the CT data of the patient;

[0307] According to the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from the CT data to the real human body;

[0308] Simulate the transport process of the particle in the target organ of the real human body and calculate the target organ dose information after the particle undergoes the transport process.

[0309] In some embodiments, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the primary particle in the target organ and water;

[0310] The process of obtaining the conversion coefficient between the dose deposition of the primary particle in the target organ and water includes:

[0311] According to the energy of the primary particle and / or the voxel size of the dose statistics, obtain the energy threshold for the ionization interaction to generate secondary electrons;

[0312] Calculate the restricted stopping power values of the primary particles in the target organ and water respectively according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, and the charge, velocity of the primary particles, and the energy threshold;

[0313] Calculate the conversion coefficient between the dose deposition of the primary particles in the target organ and water according to the restricted stopping power values of the primary particles in the target organ and water, and the densities of the target organ and water.

[0314] In some embodiments, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water;

[0315] The process of obtaining the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water includes:

[0316] Judge whether the energy of the secondary electrons is greater than the energy threshold;

[0317] When the energy of the secondary electrons is greater than the energy threshold, calculate the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water according to the atomic number, mass number, density, average ionization energy of the target organ and water, and the energy of the secondary electrons.

[0318] In some embodiments, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water;

[0319] The process of obtaining the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water includes:

[0320] Obtain a set of nuclear reaction information, which includes: the target organ dose information deposited in situ when the primary particles undergo nuclear reactions in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reactions and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reactions except the main secondary charged particles;

[0321] Calculate the target organ dose information and water dose information of the secondary fragments according to the set of nuclear reaction information;

[0322] Calculate the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water according to the target organ dose information and water dose information of the secondary fragments;

[0323] Among them, the process of obtaining the conversion coefficient between the dose deposition of the main secondary charged particles generated by the nuclear reactions in the target organ and water includes:

[0324] Calculate the restricted stopping power values of the main secondary charged particles in the target organ and water respectively according to the atomic number per unit mass, effective atomic number, average ionization energy of the target organ and water, and the charge, velocity, and energy threshold of the main secondary charged particles;

[0325] Calculate the conversion coefficient of the dose deposition of the main secondary charged particles between the target organ and water according to the restricted stopping power values of the main secondary charged particles in the target organ and water and the densities of the target organ and water.

[0326] See Figure 3 , Figure 3 FIG. is a block diagram of a structure of an electronic device 10 provided by an embodiment of the present application.

[0327] The electronic device 10 may include, for example, at least one memory 11, at least one processor 12, and a bus 13 connecting different platform systems.

[0328] The memory 11 may include a (computer) readable medium in the form of a volatile memory, such as a random access memory (RAM) 111 and / or a cache memory 112, and may further include a read only memory (ROM) 113. Among them, the memory 11 also stores a computer program, and the computer program can be executed by the processor 12 so that the processor 12 implements the steps of any of the above methods. The memory 11 may further include a utility 114 having at least one program module 115. Such program modules 115 include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. Implementations of a network environment may be included in each or some combination of these examples.

[0329] Correspondingly, the processor 12 can execute the above computer program and can execute the utility 114. The processor 12 may be one or more application specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), or other electronic components.

[0330] The bus 13 may be one or more representing several types of bus structures, including a memory bus or a memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any bus structure of multiple bus structures.

[0331] The electronic device 10 can also communicate with one or more external devices such as a keyboard, a pointing device, a Bluetooth device, etc., and can also communicate with one or more devices capable of interacting with the electronic device 10, and / or communicate with any device (such as a router, a modem, etc.) that enables the electronic device 10 to communicate with one or more other computing devices. Such communication can be carried out through the input / output interface 14. Moreover, the electronic device 10 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through the network adapter 15. The network adapter 15 can communicate with other modules of the electronic device 10 through the bus 13. It should be understood that although not shown in the figure, other hardware and / or software modules can be used in combination with the electronic device 10 in practical applications, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms, etc.

[0332] (Computer-readable storage medium)

[0333] The embodiment of the present application also provides a computer-readable storage medium, and its specific embodiment is consistent with the embodiment described in the above method embodiment and the achieved technical effect, and some content will not be elaborated again.

[0334] The computer-readable storage medium stores a computer program, and when the computer program is executed by at least one processor, it implements the steps of any one of the above methods or implements the functions of any one of the above electronic devices.

[0335] The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. In the embodiment of the present application, the computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, apparatus, or device. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0336] A computer-readable storage medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries readable program code. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. The computer-readable storage medium may also be any computer-readable medium that can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination of the foregoing. The program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including Java, C++, Python, C#, JavaScript, PHP, Ruby, Swift, Go, Kotlin, etc. The program code may be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user device through any type of network, including a local area network (LAN) or a wide area network (WAN), or, alternatively, may be connected to an external computing device (e.g., by using an Internet service provider to connect through the Internet).

[0337] (Computer program product)

[0338] An embodiment of the present application also provides a computer program product, and its specific embodiments are consistent with the embodiments and achieved technical effects described in the foregoing method embodiments, and some content will not be elaborated herein again.

[0339] The present application provides a computer program product, the computer program product includes a computer program, and when the computer program is executed by at least one processor, it implements the steps of any one of the foregoing methods or implements the functions of any one of the foregoing electronic devices.

[0340] See Figure 4 , Figure 4 is a schematic structural diagram of a computer program product provided by an embodiment of the present application.

[0341] The computer program product is used to implement the steps of any one of the foregoing methods or implement the functions of any one of the foregoing electronic devices. The computer program product may be a portable compact disc read-only memory (CD-ROM) and includes program code, and may be run on a terminal device, such as a personal computer. However, the computer program product of the present invention is not limited thereto, and the computer program product may adopt any combination of one or more computer-readable media.

[0342] This application is described from the perspectives of purpose of use, effectiveness, progress, and novelty, and has met the functional enhancement and usage requirements emphasized by the patent law. The above description and accompanying drawings of this application are only preferred embodiments of this application and do not limit this application. Therefore, all those that are similar or identical to the structure, device, features, etc. of this application, that is, all equivalent substitutions or modifications made according to the scope of the patent application of this application, shall fall within the scope of patent application protection of this application.

Claims

1. A dose conversion method, characterized in that, the method comprises: obtaining first material dose information of particles; obtaining a conversion relationship between the dose deposition of the particles between a first material and a second material; converting the first material dose information of the particles into second material dose information according to the conversion relationship; the conversion relationship is represented by a conversion coefficient table, in which each combination of particle type and particle energy corresponds to a conversion coefficient, or each type of particle corresponds to a conversion coefficient; the first material dose information is target organ dose information, and the second material dose information is water dose information; the particles include one or more of primary particles, secondary electrons and secondary fragments; wherein, according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, as well as the charge, velocity of the primary particle, and the energy threshold of secondary electrons generated by ionization interaction, the restricted stopping power values of the primary particle in the target organ and water are calculated respectively; according to the restricted stopping power values of the primary particle in the target organ and water, and the densities of the target organ and water, the conversion coefficient of the dose deposition of the primary particle between the target organ and water is calculated; when the energy of the secondary electron is greater than the energy threshold, according to the atomic number, mass number, density, average ionization energy of the target organ and water, and the energy of the secondary electron, the conversion coefficient of the dose deposition of the secondary electron between the target organ and water is calculated; for secondary fragments, a set of nuclear reaction information is collected, and the dose information of secondary fragments in the target organ and water is calculated according to the set of nuclear reaction information to determine the conversion coefficient; the set of nuclear reaction information includes: the target organ dose information deposited in place when the primary particle undergoes a nuclear reaction in the target organ, the target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and the target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles.

2. The dose conversion method according to claim 1, characterized in that, the conversion relationship can also adopt a conversion coefficient model.

3. The dose conversion method according to claim 1, characterized in that, the particles can also be protons and / or heavy ions; or, the particles are any kind of charged particles.

4. The dose conversion method according to claim 3, characterized in that, the process of obtaining the first material dose information of the particles includes: obtaining CT data of a patient; replacing each voxel in the CT data with the corresponding real human organ material according to the CT value of each voxel in the CT data to realize the mapping from the CT data to the real human body; simulating the transport process of the particles in the target organ of the real human body, and calculating the target organ dose information of the particles after the transport process.

5. The dose conversion method according to claim 4, characterized in that, the conversion relationship is used to indicate the conversion coefficient of the dose deposition of the primary particle between the target organ and water; Obtain the energy threshold for secondary electrons generated by ionization interactions according to the energy and / or dose of the primary particles and the voxel size.

6. The dose conversion method according to claim 4, wherein, the conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water; calculating the dose information of the secondary fragments in the target organ and water according to the set of nuclear reaction information, and determining the conversion coefficient; including: calculating the conversion coefficient between the dose deposition of the secondary fragments in the target organ and water according to the dose information of the secondary fragments in the target organ and the dose information in water; wherein, the process of obtaining the conversion coefficient between the dose deposition of the main secondary charged particles generated by the nuclear reaction in the target organ and water includes: respectively calculating the restricted stopping power values of the main secondary charged particles in the target organ and water according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, the charge, velocity of the main secondary charged particles, and the energy threshold; calculating the conversion coefficient between the dose deposition of the main secondary charged particles in the target organ and water according to the restricted stopping power values of the main secondary charged particles in the target organ and water and the densities of the target organ and water.

7. An electronic device, wherein, the electronic device includes a memory and at least one processor, the memory stores a computer program, and the at least one processor is configured to implement the following steps when executing the computer program: obtain the first material dose information of the particles; obtain the conversion relationship between the dose deposition of the particles in the first material and the second material; convert the first material dose information of the particles into the second material dose information according to the conversion relationship; the conversion relationship is represented by a conversion coefficient table, in which each combination of particle type and particle energy corresponds to a conversion coefficient, or each type of particle corresponds to a conversion coefficient; the first material dose information is the dose information of the target organ, and the second material dose information is the dose information in water; the particles include one or more of primary particles, secondary electrons, and secondary fragments; wherein, respectively calculating the restricted stopping power values of the primary particles in the target organ and water according to the number of atoms per unit mass, effective atomic number, average ionization energy of the target organ and water, the charge, velocity of the primary particles, and the energy threshold for secondary electrons generated by ionization interactions; calculating the conversion coefficient between the dose deposition of the primary particles in the target organ and water according to the restricted stopping power values of the primary particles in the target organ and water and the densities of the target organ and water; when the energy of the secondary electrons is greater than the energy threshold, calculating the conversion coefficient between the dose deposition of the secondary electrons in the target organ and water according to the atomic number, mass number, density, average ionization energy of the target organ and water, and the energy of the secondary electrons; For secondary fragments, collect a set of nuclear reaction information, calculate the dose information of the secondary fragments in the target organ and in water according to the set of nuclear reaction information, and determine the conversion coefficient; the set of nuclear reaction information includes: the dose information of the target organ deposited in situ when the primary particle undergoes a nuclear reaction in the target organ, the dose information of the main secondary charged particles generated by the nuclear reaction in the target organ and their corresponding conversion coefficients, and the dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles in the target organ.

8. A computer-readable storage medium, characterized in that, the computer-readable storage medium stores a computer program, and when the computer program is executed by at least one processor, it implements the steps of the dose conversion method according to any one of claims 1-6 or implements the functions of the electronic device according to claim 7.

9. A computer program product, characterized in that, the computer program product includes a computer program, and when the computer program is executed by at least one processor, it implements the steps of the dose conversion method according to any one of claims 1-6 or implements the functions of the electronic device according to claim 7.

10. A radiotherapy system, characterized in that, it includes: a mapping device for acquiring CT data of a patient; According to the CT value of each voxel in the CT data, replace each voxel with the corresponding real human organ material to realize the mapping from CT data to the real human body; a device for simulating particle transport, which is used to simulate the transport process of particles in the target organ of the real human body and calculate the dose information of the target organ after the particle transport process; a dose conversion device for converting the dose information of the target organ of the particle into water dose information by using the dose conversion method according to any one of claims 1-6; a device for determining the human dose, which is used to determine the dose used in radiotherapy according to the desired dose information after the water dose information of the particle matches the desired dose information.

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