Dose conversion method, radiotherapy system and related device

Abstract

The invention provides a dose conversion method, electronic equipment, a computer readable storage medium, a computer program product and a radiotherapy system. The method comprises the following steps: acquiring first material dose information of particles; obtaining a conversion relation of dose deposition of the particles between the first material and the second material; and converting the first material dosage information of the particles into second material dosage information according to the conversion relation. According to the method, the dose deposition conversion relation of the particles is considered, and the dose information of the particles in different materials is quickly and accurately converted. The conversion method has important application value in (proton, heavy ion and the like) radiotherapy and other radiation dose scenes (such as the field of space radiation dose and the like), can realize comparison and analysis of particle dose in different tissues and media, and provides technical support for optimization and personalization of particle therapy and other radiation dose scenes.

Description

Technical Field

[0001] The present application relates to the technical field of radiotherapy and space radiation, and in particular 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 method used to treat diseases such as cancer. In radiotherapy, particle dose deposition is a key parameter that reflects the distribution of radiation energy in the patient's body. In radiotherapy planning, doctors need to accurately understand the particle dose deposition in different tissues and media to ensure the accuracy and safety of treatment.

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

[0004] 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 related technologies. Summary of the invention

[0005] The purpose of the present 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 dose deposition conversion relationship of particles.

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

[0007] The present application provides a dosage conversion method, the method comprising:

[0008] Acquiring first material dosage information of particles;

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

[0010] According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage information.

[0011] The beneficial effect of this technical solution is that 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 (proton, heavy ion, etc.) radiotherapy 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 the particle into the second material dose, effective dose comparison and data analysis can be performed 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 implementations, 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 particle corresponds to a conversion coefficient; or,

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

[0014] The beneficial effect of the technical solution is that a conversion coefficient table or a conversion coefficient model can be used to represent the conversion relationship. For the implementation 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. In addition, a conversion coefficient model can also be used to represent the conversion relationship.

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

[0016] The method using the 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 the 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 achieve the conversion relationship is flexible and adaptable. 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 nonlinear models) and higher accuracy requirements.

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

[0019] The particles are protons and / or heavy ions; or,

[0020] The particles are any charged particles.

[0021] The beneficial effect of this technical solution is that particles can include one or more of primary particles, secondary electrons and secondary fragments. Primary particles are initially incident charged particles (i.e. particles directly generated by the radiation source), which mainly lose energy through ionization interaction with matter; secondary electrons are derived from ionization interaction between primary particles, secondary fragments and matter, and lose energy through ionization interaction with matter; secondary fragments are generated by nuclear reactions between primary particles and matter, in which charged nuclear fragments (such as H-2, H-3, He-3, etc.) lose energy through ionization interaction, and uncharged fragments such as neutrons mainly lose energy through elastic and inelastic collisions with matter.

[0022] In addition, the particles can 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, etc., which have higher mass and energy and can produce more complex interactions and energy deposition patterns in tissues.

[0023] In addition, the particles can also be any kind of charged particles. Charged particles include protons, heavy ions, and other charged particles, such as helium ions, lithium ions, etc. These charged particles have different energy losses in different materials, probabilities of nuclear reactions, and types and energies of secondary fragments produced by nuclear reactions. Therefore, it is necessary to perform corresponding dose conversion for different types of particles.

[0024] By considering the dose conversion relationship between 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. It can meet the dose conversion requirements of different particles and different treatment scenarios, and improve the accuracy and personalization of radiotherapy.

[0025] In some possible implementations, the first material dosage information is target organ dosage information, and the second material dosage information is water dosage information;

[0026] The process of obtaining the first material dosage information of the particles includes:

[0027] Obtain CT data of the patient;

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

[0029] The transport process of the particles in the target organs of a real human body is simulated, and the target organ dose information after the particles have been transported is calculated.

[0030] The beneficial effect of this technical solution is that 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 organ, that is, the transport simulation and dose calculation can be performed separately for each organ. Specifically, the transport process of particles in each organ can be simulated separately to obtain the organ dose information corresponding to each organ. In addition, this method can consider the physical process of the interaction between particles and materials and the energy deposition mode, set different conversion coefficients for different particles, and 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.

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

[0032] The benefit of this is that by combining CT data and particle transport simulation, dose conversion from 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 conversion of it into a dose in water to meet the need to express the dose as a dose in water in clinical practice. 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 calculations. Therefore, this dose conversion method is of great significance for the realization of precise radiotherapy and clinical dose calculations.

[0033] In some possible implementations, the conversion relationship is used to indicate a conversion coefficient between the dose deposition of the primary particles and water;

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

[0035] Obtaining an energy threshold for generating secondary electrons by ionization interaction according to the energy and / or dose statistical voxel size of the primary particles;

[0036] Calculating the confinement stopping power values ​​of the primary particles in the target organ and water, respectively, according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, the charge, the velocity, and the energy threshold of the primary particles;

[0037] The conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary particles in the target organ and water, and the densities of the target organ and water.

[0038] The beneficial effect of the technical solution is that the conversion relationship is used to indicate the conversion coefficient of the dose deposition of primary particles between the target organ and water. In order to obtain the dose deposition conversion coefficient of the primary particles, first, the energy threshold of the ionization interaction to produce secondary electrons is obtained, and the energy threshold of the ionization interaction to produce secondary electrons is determined according to the energy and / or dose statistical voxel size of the primary particles. The threshold is used to screen out secondary electrons with energy higher than the threshold for subsequent dose conversion calculations. Secondly, the constraint stopping power value is calculated, and the constraint stopping power value of the primary particles in the target organ and water is calculated according to the number of atoms per unit mass, the effective atomic number, and the average ionization energy of the target organ, and the number of atoms per unit mass, the effective atomic number, and the average ionization energy of water, as well as the charge, speed, and energy threshold of the primary particles. The constraint stopping power value is related to the energy of the particles, the composition and characteristics of the material, etc. After that, the conversion coefficient is calculated, and the conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the constraint stopping power value of the primary particles in the target organ and water and the energy threshold of the secondary electrons, as well as the density of the target organ and water. The conversion coefficient represents the dose conversion relationship from the target organ to the water, which converts the dose in the target organ into the corresponding dose in the water. Through the above steps, the conversion coefficient of the dose deposition of the primary particles between the target organ and the water can be obtained. In this way, the dose in the target organ can be converted into the dose in the water, realizing the conversion from tissue dose to water dose. The advantage of this is that by considering factors such as the constraint stopping power and the density of the material, as well as the energy of the particles and the dose statistical voxel size, the dose conversion coefficient can be calculated more accurately, improving the accuracy and reliability of the dose calculation, and providing support for the implementation of precise radiotherapy.

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

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

[0041] Determining whether the energy of the secondary electron is greater than the energy threshold;

[0042] When the energy of the secondary electrons is greater than the energy threshold, the 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, average ionization energy of the target organ and water and the energy of the secondary electrons.

[0043] The beneficial effect of the technical solution is that 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 determined whether the energy is greater than the energy threshold, and for each secondary electron, it is determined whether its energy is greater than the preset energy threshold. Only secondary electrons with energy greater than the threshold will undergo subsequent conversion coefficient calculations, otherwise their energy is deposited in situ, and their contribution to the dose is included in the confinement stopping power of the primary particles. Secondly, the conversion coefficient is calculated. For secondary electrons with energy greater than the threshold, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water is calculated based on the atomic number, mass number, density, average ionization energy of the target organ and water, and the energy of the secondary electrons. Through the above steps, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water can be obtained. The conversion coefficient takes into account the energy of the 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, thereby 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 implementations, the conversion relationship is used to indicate a conversion coefficient between the dose deposition of the secondary fragments and water;

[0045] The process of acquiring the conversion coefficient between the dose deposition of the secondary fragments and the target organ and water comprises:

[0046] Acquire a nuclear reaction information set, the nuclear reaction information set including: target organ dose information of the primary particles deposited in situ when a nuclear reaction occurs in the target organ, target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles;

[0047] Calculating target organ dose information and water dose information of the secondary fragments according to the nuclear reaction information set;

[0048] Calculating a conversion coefficient between the target organ and water for the dose deposition of the secondary fragments according to the target organ dose information and the dose information in water of the secondary fragments;

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

[0050] Calculating the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water respectively according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, and the charge, velocity, and the energy threshold of the primary and secondary charged particles;

[0051] The conversion coefficient of the dose deposition of the primary and secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water, and the densities of the target organ and water.

[0052] The beneficial effect of this technical solution is that the conversion relationship is used to indicate the conversion coefficient of the dose deposition of secondary fragments between the target organ and water. First, a nuclear reaction information set is obtained to collect information about the nuclear reaction, including the target organ dose information when the primary particles undergo a nuclear reaction 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, the target organ dose information and the dose information in the water are calculated, and the dose deposition of secondary fragments in the target organ and water is calculated based on the nuclear reaction information set. This includes calculating the dose of the secondary fragments in the target organ and the dose in the water to ensure that the dose conversion process is accurately captured. After that, the conversion coefficient is calculated, and the conversion coefficient of the dose deposition of the secondary fragments between the target organ and water is calculated based on the dose information of the secondary fragments in the target organ and in the water.

[0053] For the conversion coefficient of the dose deposition of the primary secondary charged particles between the target organ and water (i.e., the conversion coefficient corresponding to the primary secondary charged particles produced by the nuclear reaction), first, the confinement stopping power value is calculated. According to the number of atoms per unit mass of the target organ and water, the effective atomic number, the average ionization energy, and the charge, speed, and energy threshold of the primary secondary charged particles, the confinement stopping power values ​​of the primary secondary charged particles in the target organ and water are calculated respectively. The confinement stopping power value reflects the degree of energy loss of the particles when interacting with the atoms of the material in different media. Secondly, the conversion coefficient is calculated. According to the confinement stopping power value of the primary secondary charged particles in the target organ and water and the density of the target organ and water, the conversion coefficient of the dose deposition of the primary secondary charged particles between the target organ and water is calculated. In this way, the dose deposition of the primary 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 acquiring a set of nuclear reaction information and calculating conversion coefficients, the dose distribution of secondary fragments in target organs 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, the electronic device comprising a memory and at least one processor, the memory storing a computer program, and the at least one processor being configured to implement the following steps when executing the computer program:

[0055] Acquiring first material dosage information of particles;

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

[0057] According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage 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 of the above methods or implements the functions of any of the above electronic devices.

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

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

[0061] A mapping device, used to obtain CT data of a patient; according to the CT value of each voxel in the CT data, each voxel is replaced with a corresponding real human organ material to achieve mapping from the CT data to the real human body;

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

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

[0064] The device for determining human body dose is used to determine the dose used in radiotherapy according to the expected dose information after the water dose information of the particles matches the expected dose information.

[0065] Radiotherapy system is a medical device used to treat diseases such as cancer. The core of radiotherapy system is to ensure that the dose distribution of particles in the patient's body meets the expected 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 distribution with existing technologies.

[0066] The beneficial effect of the technical solution is that: a radiotherapy system is provided, which is designed to provide accurate 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 to the human anatomical structure, the mapping from CT data to the real human body is realized, thereby 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 target organ dose information of the particles after the 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 dose conversion methods provided above 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 expected dose information, and determine the dose used in radiotherapy according to the required treatment dose. By matching the dose in water with the expected dose, the radiotherapy plan can be adjusted to meet specific treatment needs. This radiotherapy system has the ability to accurately calculate and adjust dose distribution, which helps to improve the accuracy and safety of radiotherapy. It can provide support for doctors to develop personalized treatment plans, improve treatment effects and reduce the occurrence of side effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present application is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0068] Figure 1 It is a flow chart of a dosage conversion method provided in an embodiment of the present application.

[0069] Figure 2 This is a flow chart for converting an organ dose of a particle to an in-water dose provided in an embodiment of the present application.

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

[0071] Figure 4 It is a structural diagram of a computer program product provided in an embodiment of the present application. DETAILED DESCRIPTION

[0072] The technical solution in the present application will be described below in conjunction with the drawings and specific implementation methods of the specification of the present application. It should be noted that, under the premise of no conflict, the various implementation methods or technical features described below can be arbitrarily combined to form a new implementation method.

[0073] In the embodiments of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any implementation or design scheme described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other implementations or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0074] The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor does it indicate any special limitation on the quantity in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0075] The following is a brief description of the technical field and related terms of the embodiments of the present application.

[0076] Proton therapy is a radiotherapy technology 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, which can reduce damage to normal tissues and improve clinical treatment effects.

[0077] The principle of proton therapy is to use 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 decrease sharply until it stops. This characteristic enables the proton beam to release the maximum dose in the tumor, while reducing the dose deposition in the normal tissue around the tumor, thereby reducing the side effects caused by treatment. Proton therapy is suitable for many types of tumors, including pediatric tumors, cranial tumors, head and neck tumors, chest tumors, abdominal tumors, bone and soft tissue tumors, etc. Proton therapy is particularly suitable for tumors around critical organs or those that are sensitive to radiation. Compared with traditional radiotherapy, proton therapy can better protect normal tissues and organs and reduce the side effects caused by treatment. Especially for pediatric patients, proton therapy can reduce long-term treatment sequelae and reduce the risk of secondary tumors. Some studies have shown that proton therapy can provide therapeutic effects comparable to traditional radiotherapy in some cases, while reducing adverse reactions.

[0078] Accurate calculation of dose distribution is the premise and guarantee for proton therapy. In radiotherapy, it is first necessary to formulate a corresponding treatment plan and program based on the patient's tumor location information. The most critical part is to calculate the dose distribution of particles in the patient's body.

[0079] The Monte Carlo (MC) method is known as the gold standard for particle dose calculation. Compared with traditional analytical algorithms, it has the advantages of high calculation accuracy. In clinical radiotherapy, when MC calculates the dose deposition of particles in the human body's Regions of interest (ROI), it will replace each voxel on the CT image with the corresponding real human organ material based on information such as the treatment site and CT value, thereby achieving mapping from virtual images to real human bodies, and transporting and simulating particles in human tissues. Due to the real material properties, MC's transport and simulation of particles, and the interaction of particles are all considered to occur in human tissues, and the resulting dose deposition belongs to 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 difference 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 is considered to be the dose in water. The analytical algorithm has high computational efficiency and low requirements for computer hardware. It is currently the most widely used and common algorithm for dose calculation.

[0081] Due to historical reasons (e.g., analytical algorithms were the earliest method used for clinical dose calculation; clinical basic data were all collected in water), ROI doses are usually expressed as doses in water in clinical treatment. Therefore, in order to facilitate comparison, verification and unified expression, in many cases, the dose calculation results of MC need to be converted, that is, the dose in the tissue is converted to the dose in water.

[0082] Many scholars have conducted research on the conversion of proton tissue dose deposition calculated by MC to the corresponding dose deposition in water, 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) But in general, these methods have certain limitations or irrationality, and most of them remain at the research level, and it is difficult to actually apply them to MC clinical dose calculation conversion. The specific summary is as follows:

[0083] 1. Approximate the proton ionization interaction energy loss process as unconstrained energy loss. When MC simulates proton ionization energy loss, due to the setting of parameters such as secondary product threshold and energy cutoff, as well as the constraints of the energy range that can be simulated by the physical model, the process is physically constrained energy loss. In the existing conversion methods, the process is basically approximated as unconstrained energy loss. This is different from the basic principles of physics and is not rigorous enough;

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

[0085] 3. The conversion of nuclear reaction dose deposition is too long or simple. The types and yields of secondary fragments produced by nuclear reactions between protons and 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 the results vary greatly between different models. In addition, most of the nuclear fragments produced by protons are their isotopes, while the yields of heavy nuclei such as α and He-3 are relatively low. Therefore, when dealing with this process and the subsequent particle dose conversion, it is not possible to simply deposit its energy on the spot or perform dose conversion on all particles, which will 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 divided according to density, and the types of materials are limited, which cannot fully cover all organs and tissues of the human body. ICRP Report 145 divides the organs of the reference person into more than 50 types of materials (reference information: ICRPPublication 145.ADULT MESH-TYPE REFERENCE COMPUTATIONAL PHANTOMS.2019). The data shows that organs with different elemental components in different parts may have the same density, such as the brain and 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 particle arc radiotherapy plan currently in clinical use has the following defects:

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

[0089] 2. The use of unconstrained stopping power for the dose deposition conversion occurring in the interaction of primary particles ionizing 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 locally;

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

[0092] This application provides a method for accurately converting particle dose deposition from organs (or human tissues) to water under different physical processes based on the energy and type information of the incident particles, combined with the physical process of their interaction with matter. Based on the reference person information provided by ICPR, factors such as gender and location are fully considered, typical tissues and organs are selected, and a conversion coefficient table or conversion coefficient model suitable for Monte Carlo (MC) algorithms is generated based on the physical properties of the organs and the determined conversion method, thereby realizing the rapid and accurate conversion of the organ dose (or tissue dose) obtained by the MC algorithm to the dose in water.

[0093] There is no report on the conversion of organ doses of heavy ions (α and carbon ions) calculated by MC to doses in water, but the physical process of their interaction with matter to deposit energy is the same as that of protons. Therefore, the dose conversion method established in this application is also applicable to heavy ions.

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

[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 related technologies.

[0096] The solutions provided in the embodiments of the present application involve technologies such as radiotherapy, space radiation, and simulation, which are specifically described by the following embodiments. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments.

[0097] (Dose conversion method)

[0098] See also Figure 1 , Figure 1 It is a flow chart of a dosage conversion method provided in an embodiment of the present application.

[0099] The present application embodiment provides a dosage conversion method, the method comprising:

[0100] Step S101: obtaining first material dosage information of particles;

[0101] Step S102: obtaining a conversion relationship between the first material and the second material for the particle dose deposition;

[0102] Step S103: converting the first material dosage information of the particles into second material dosage information according to the conversion relationship.

[0103] In radiation therapy, particles refer to charged ions or atomic nuclei, such as protons, carbon ions, etc. These particles are used to deliver energy and produce dose effects.

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

[0105] The first material dose information of the particles, i.e., the dose deposition (information) of the particles in the first material, refers to the dose distribution of the particles in the first material. The first material may be, for example, an organ, tissue or other material of a patient.

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

[0107] The conversion relationship represents the dose conversion relationship between the first material and the second material of the particles. The conversion relationship can be represented by a conversion coefficient table or a conversion coefficient model, which 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 the dose deposition of protons in the patient's organs, that is, the first material dose information, is first obtained. Then, the conversion relationship between protons in organs and water needs to be obtained in order to convert the organ dose information into water dose information. 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 water dose information, 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 radiation on Earth. It includes particles captured 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 0.45Sv, which requires 50g / cm 2 The thickness of the aluminum shield. As the mass shield thickness increases, the contribution of the secondary radiation dose generated by the interaction between the primary space radiation and the shielding material gradually increases. (See the article "Active Protection Methods for Manned Space Radiation" in "Aerospace Medicine and Medical Engineering" published in June 2012, article number: 1002-0837.2012.03.017) In deep space exploration, the heavy ions in GCR and the protons in SPE are the main shielding objects that need to be considered. The GCR radiation equivalent dose rate suffered by astronauts is about 1mSv per day. When SPE occurs, a high flux of high-energy protons lasts 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" in "High Power Laser and Particle Beam" published 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 stream ejected from the solar active region during solar eruptions. These particles are mainly protons, but also include other types of particles. Galactic cosmic rays refer to high-energy particles from the Milky Way outside the solar system. These particles are mainly protons (accounting for 89%), but 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, the first material dose information of the particle is obtained. For example, the dose deposition of (protons, heavy charged) particles in the universe in astronauts and spacecraft components Si materials (first materials) can be calculated using MC (i.e., Monte Carlo algorithm). Secondly, the conversion relationship between the dose deposition of the particles and the first material and the second material is obtained. For example, the conversion coefficient of the dose deposition of particles in the universe between astronauts, Si materials and water (second material) can be obtained by experimental or theoretical calculation. Finally, according to the conversion relationship, the first material dose information of the particle is converted into the second material dose information. For example, according to the conversion coefficient of the dose deposition of particles in the universe between astronauts, aerospace devices Si and water, the dose deposition of particles in the universe in astronauts and aerospace devices Si is converted into dose deposition in water. Among them, the particles in the universe mainly include galactic cosmic rays and solar particle events. Si is silicon.

[0111] Therefore, by considering the particle dose deposition conversion relationship, the dose information of particles in different materials can be quickly and accurately converted. This conversion method has important application value in (proton, heavy ion, etc.) radiotherapy 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 the particle into the second material dose, effective dose comparison and data analysis can be performed 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 which each combination of particle type and particle energy corresponds to a conversion coefficient, or each particle corresponds to a conversion coefficient; or,

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

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

[0115] 1. Conversion coefficient table: The conversion coefficient table represents the conversion relationship between the dose deposition of the first material and the second material in a tabular form. In the conversion coefficient table, each combination of particle type and particle energy corresponds to a conversion coefficient (from the dose of the first material to the dose of the second material), or each particle corresponds to a conversion coefficient. The conversion coefficient refers to a parameter of the dose deposition conversion relationship between particles in different materials. For example, for combinations 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 to the dose information of the second material. For example, in radiotherapy, the conversion coefficient can be used to convert the dose deposition of protons in organs (i.e., organ dose) into 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 between particle doses in different materials. This model is established based on factors such as the physical properties of particles, material properties, and interaction mechanisms. Through the conversion coefficient model, the conversion coefficient can be calculated based on the type of particles and specific physical parameters, thereby realizing the conversion of the first material dose information to the second material dose information. For example, the conversion coefficient model can be established based on the theoretical energy loss calculation formula of particles in different materials.

[0117] 3. Transformation matrix. The transformation matrix can be a linear matrix or a nonlinear matrix.

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

[0119] For example, suppose a conversion coefficient table is used to represent the conversion relationship. A conversion coefficient table is created, in which a corresponding conversion coefficient is provided for each combination of protons (a type of particle) and different energies for an organ such as the lung. For example, for a 100MeV proton, 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 proton dose information in the lung to the dose information in water, the calculation can be performed by looking up the table and using the corresponding conversion coefficient.

[0120] Another possible implementation method is to use a conversion coefficient model. Based on the energy, charge, speed of protons and the physical parameters of different materials, such as density and ionization energy, a conversion coefficient model can be established to describe the dose conversion relationship between protons between materials. Through this conversion coefficient model, the conversion coefficient can be calculated based on the given input information, thereby realizing the conversion of dose. In other words, 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 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. In addition, a conversion coefficient model can also be used to represent the conversion relationship.

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

[0123] The method using the 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. The conversion coefficient model can also be obtained by training the initial model using a training set through machine learning, deep learning and other methods. 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 achieve the conversion relationship is flexible and adaptable. 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 nonlinear models) and higher accuracy requirements.

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

[0126] The particles are protons and / or heavy ions; or,

[0127] The particles are any charged particles.

[0128] Thus, particles may include one or more of primary particles, secondary electrons and secondary fragments. Primary particles are initially incident charged particles (i.e. particles directly generated by the radiation source), which mainly lose energy through ionization interactions with matter; secondary electrons are derived from ionization interactions between primary particles, secondary fragments and matter, and lose energy through ionization interactions with matter; secondary fragments are generated by nuclear reactions between primary particles and matter, in which 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.

[0129] In addition, particles can 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 interactions and energy deposition patterns in tissues.

[0130] In addition, the particles can also be any kind of charged particles. Charged particles include protons, heavy ions, and other charged particles, such as helium ions, lithium ions, etc. These charged particles have different energy losses in different materials, probabilities of nuclear reactions, and types and energies of secondary fragments produced by nuclear reactions. Therefore, it is necessary to perform corresponding dose conversion for different types of particles.

[0131] By considering the dose conversion relationship between 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. It can meet the dose conversion requirements of different particles and different treatment scenarios, and improve the accuracy and personalization of radiotherapy.

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

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

[0134] Obtain medical imaging data of patients;

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

[0136] The transport process of the particles in the target organs of a real human body is simulated, and the target organ dose information after the particles have been transported is calculated.

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

[0138] As an example, when the medical image data is CT data, the statistical unit may be a voxel, and the corresponding numerical 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 a pixel in a two-dimensional image, but has three-dimensional properties. 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, and the thickness of the slice. The CT value of a voxel indicates the density or other properties of the material in the cube.

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

[0141] The process of obtaining the first material dosage information of the particles includes:

[0142] Obtain CT data of the patient;

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

[0144] The transport process of the particles in the target organs of a real human body is simulated, and the target organ dose information after the particles have been transported is calculated.

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

[0146] According to the organ basic database, the patient's personal information and the CT value of each voxel in the CT data, each voxel is replaced with a corresponding real human organ material to achieve mapping from CT data to a real human body.

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

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

[0149] CT data is medical imaging data obtained through computed tomography (CT scan). CT scans use X-rays or other radiation sources to scan patients in different directions, and then generate three-dimensional images with voxels (volume pixels) through computational reconstruction technology. CT data provides detailed information about the internal structure and tissue density of the human body.

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

[0151] The target organ is the organ that needs to be treated with radiation therapy. It can be any organ. For example, when treating lung cancer, the lung is the target organ. The target organ can be any of the following organs: cerebrum, cerebellum, brain stem, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus gland, 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 by which particles propagate in matter. In radiotherapy, the transport process of particles in the target organs inside the patient's body can be simulated to calculate the dose deposition in the target organs after the particles have completed transport.

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

[0154] The reference person can be, for example, an ICRP reference person or a reference person from a specific country or region. As an example, the reference person can be a Chinese reference person. 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, used in radiation protection calculations as a reference object. The ICRP reference person was originally defined as a male aged 20-30 years old, weighing 70 kg, 170 cm tall, living in a climate with an average temperature of 10-20 degrees Celsius. But over time, ICRP has expanded this definition to include reference persons of different age groups and genders. Currently, ICRP provides data on a range of reference persons, including males and females, with each gender including newborns, 1 year old, 5 years old, 10 years old, 15 years old and adults.

[0155] Among them, gender information includes male and female. The human body is composed of many different parts, including the head, neck, trunk, limbs, etc. The trunk includes the chest, abdomen and back. The limbs include upper limbs and lower limbs. The upper limbs include shoulders, upper arms, forearms, wrists and hands. The lower limbs include 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 basic database may be an organ basic database based on gender and position. In other embodiments, the organ basic database may be an organ basic database based on gender, position and age.

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

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

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

[0160] Thus, the first material dose information may be the dose information of the target organ, and the second material dose information may be the dose information in water. The target organ may be any organ, that is, transport simulation and dose calculation may be performed for each organ separately. Specifically, the transport process of particles in each organ may be simulated separately to obtain the organ dose information corresponding to each organ. Moreover, the method may consider the physical process of the interaction between particles and materials 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.

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

[0162] The benefit of this is that by combining CT data and particle transport simulation, dose conversion from 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 conversion of it into a dose in water to meet the need to express the dose as a dose in water in clinical practice. 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 calculations. Therefore, this dose conversion method is of great significance for the realization of precise radiotherapy and clinical dose calculations.

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

[0164] As an example, particles and their energy deposition methods are divided into three categories according to the type of physical interaction: (1) primary particles (i.e., primary incident particles), which mainly lose energy through ionization interactions with matter; (2) secondary electrons, which come from ionization interactions between primary particles, secondary fragments and matter, and lose energy through ionization with matter; (3) secondary fragments, which are produced by nuclear reactions between primary particles and matter, among which 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.

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

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

[0167] The dose information of the multiple particles in water is calculated based on the target organ dose information of the multiple particles and the conversion coefficient corresponding to each particle, wherein 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 underwater dose information of the multiple particles is the underwater dose information corresponding to the proton therapy plan (ie, proton radiotherapy plan).

[0169] In some embodiments, the conversion relationship is used to indicate a conversion coefficient between the dose deposition of the primary particles and water;

[0170] The process of obtaining the conversion coefficient between the dose deposition of the primary particles on the target organ and water comprises:

[0171] Obtaining an energy threshold for generating secondary electrons by ionization interaction according to the energy and / or dose statistical voxel size of the primary particles;

[0172] Calculating the confinement stopping power values ​​of the primary particles in the target organ and water, respectively, according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, the charge, the velocity, and the energy threshold of the primary particles;

[0173] The conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary particles in the target organ and water, and the densities of the target organ and water.

[0174] In some embodiments, the calculation of the confinement stopping power values ​​of the primary particles in the target organ and water, respectively, based on the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, and the charge, velocity, and energy threshold of the primary particles, comprises:

[0175] Calculating the confinement stopping power value of the primary particle in the target organ according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ, the charge, the velocity, and the energy threshold of the primary particle;

[0176] The confinement stopping power value of the primary particle in water is calculated based on the number of atoms per unit mass, the effective atomic number, the average ionization energy of water, the charge, the speed, and the energy threshold of the primary particle.

[0177] In this embodiment, the primary particles refer to the primary incident particles used in radiotherapy, which may be protons, carbon ions, etc.

[0178] The energy threshold refers to the minimum energy required for the ionization interaction to produce secondary electrons. This value depends on one or more of the energy of the primary particle and the dose statistical voxel size. The energy of the primary particle may include, for example, the kinetic energy of the primary particle. The dose statistical voxel size is the dose statistical voxel size. Since the generation threshold of secondary electrons is set, only electrons with kinetic energy higher than the threshold will be generated and tracked. For example, the energy threshold may be 10 keV, which means that only when the energy of the electron is higher than 10 keV will it be generated and tracked. Otherwise, the energy of the electron is deposited in situ, and its contribution to the dose is included in the confinement stopping power of the primary particle that produces the electron.

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

[0180] The effective atomic number is the equivalent atomic number that a substance exhibits when it interacts 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 about 7.42.

[0181] Average ionization energy refers to the average energy required to ionize an atom or molecule. Its unit is eV. For example, the average ionization energy of water molecules is about 78eV.

[0182] Charge refers to the amount of charge an object carries. Its unit is coulomb (C). Charge determines the nature of how a particle interacts with other charged particles or electric fields. For example, an electron has a negative charge of -1.6×10 -19 C. For primary particles, such as protons, the charge is usually positive (+1.6×10 -19 C).

[0183] Speed ​​refers to how fast an object is moving. It is measured in meters per second (m / s). The speed of a primary particle affects how it interacts 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 and to energies of up to 250 million electron volts.

[0184] Density is the ratio of the mass of a medium to its volume, and can be expressed in grams per cubic centimeter (g / cm3). It indicates how compact the medium is and how strong the interaction between molecules is. For target organs and water, their densities are determined based on their physical properties. For example, water has a density of about 1g / cm3.

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

[0186] Thus, the conversion relationship can be used to indicate the conversion coefficient of the dose deposition of primary particles between the target organ and water. In order to obtain the dose deposition conversion coefficient of the primary particles, first, the energy threshold of the ionization interaction to produce secondary electrons is obtained. For example, the energy threshold of the ionization interaction to produce secondary electrons can be determined according to the energy and / or dose statistical voxel size of the primary particles. The threshold is used to screen out secondary electrons with energy higher than the threshold for subsequent dose conversion calculations. Secondly, the constraint stopping power value is calculated, and the constraint stopping power value of the primary particles in the target organ and the constraint stopping power value of the primary particles in water are calculated according to the unit mass atomic number, effective atomic number, and average ionization energy of the target organ, and the unit mass atomic number, effective atomic number, and average ionization energy of water, as well as the charge, speed, and energy threshold of the primary particles. The constraint stopping power value is related to the energy of the particles, the composition and characteristics of the material, etc. After that, the conversion coefficient is calculated, and the conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the constraint stopping power value of the primary particles in the target organ and water, as well as the density of the target organ and the density of water. The conversion coefficient represents the dose conversion relationship from the target organ to the water, which converts the dose in the target organ into the corresponding dose in the water. Through the above steps, the conversion coefficient of the dose deposition of the primary particles between the target organ and the water can be obtained. In this way, the dose in the target organ can be converted into the dose in the water, realizing the conversion from tissue dose to water dose. The advantage of this is that by considering factors such as the constraint stopping power and the density of the material, as well as the energy of the particles and the dose statistical voxel size, the dose conversion coefficient can be calculated more accurately, improving the accuracy and reliability of the dose calculation, and providing support for the implementation of precise radiotherapy.

[0187] For example, when treating lung cancer, the target organ is the lung. First, the voxel size is statistically calculated based on the energy and dose of the protons to obtain the energy threshold for the ionization interaction to produce secondary electrons. Secondly, the confinement stopping power values ​​of protons in the lungs and water are calculated based on the number of atoms per unit mass of the lungs and water, the effective atomic number, the average ionization energy, and the charge, speed, and energy threshold of the protons. After that, the conversion coefficient of the proton dose deposition between the lungs and water is calculated based on the confinement stopping power values ​​of protons in the lungs and water and the density of the lungs and water.

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

[0189] The type and energy of the primary particles and the type of the target organ are input into a conversion coefficient model to obtain a conversion coefficient between the dose deposition of the primary particles on the target organ and water.

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

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

[0192] Determining whether the energy of the secondary electron is greater than the energy threshold;

[0193] When the energy of the secondary electrons is greater than the energy threshold, the 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, average ionization energy of the target organ and water and the energy of the secondary electrons.

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

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

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

[0197] In calculating the dose deposition conversion factor for secondary electrons, the density of the target organ and water, and the average ionization energy 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. In order to obtain the dose deposition conversion coefficient of secondary electrons, first, it is determined whether the energy is greater than the energy threshold, and for each secondary electron, it is determined whether its energy is greater than the preset energy threshold. Only secondary electrons with energy greater than the threshold will undergo subsequent conversion coefficient calculations, otherwise their energy is deposited in situ, and their contribution to the dose is included in the confinement stopping power of the primary particles. Secondly, the conversion coefficient is calculated. For secondary electrons with energy greater than the threshold, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water is calculated based on the atomic number, mass number, density, average ionization energy of the target organ, the atomic number, mass number, density, average ionization energy of water, and the energy of the secondary electrons. Through the above steps, the conversion coefficient of the dose deposition of secondary electrons between the target organ and water can be obtained. The conversion coefficient takes into account the energy of the 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 to the dose in water, thereby 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.

[0200] For example, in the treatment of lung cancer, it is assumed that the dose conversion coefficient of secondary electrons between the lungs (target organ) and water needs to be calculated. First, it is determined whether the energy of the secondary electrons is greater than an energy threshold (e.g., 10 keV). If the energy of the secondary electrons is greater than the energy threshold, the conversion coefficient of the dose deposition of the secondary electrons between the lungs and water is calculated based on the atomic number, mass number, density, average ionization energy of the lungs and water and the energy of the secondary electrons.

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

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

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

[0205] Acquire a nuclear reaction information set, the nuclear reaction information set including: target organ dose information of the primary particles deposited in situ when a nuclear reaction occurs in the target organ, target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles;

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

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

[0208] The process of obtaining the conversion coefficient of the dose deposition of the primary secondary charged particles generated by the nuclear reaction between the target organ and water includes:

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

[0210] The conversion coefficient of the dose deposition of the primary and secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water, and the densities of the target organ and water.

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

[0213] The target organ dose information of the primary particles deposited in situ when a nuclear reaction occurs 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 the other secondary charged particles generated by the nuclear reaction except the main secondary charged particles are summed and calculated as the target organ dose information of the secondary fragments;

[0214] The target organ dose information of the primary particles deposited locally when a nuclear reaction occurs in the target organ, the target organ dose information of the main secondary charged particles produced by the nuclear reaction and the product of their corresponding conversion coefficients, and the target organ dose information of the secondary charged particles other than the main secondary charged particles produced by the nuclear reaction are summed and 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 secondary fragments corresponding to nuclear reactions, the difference between the two lies in the second item in the summation calculation. The former corresponds to "the target organ dose information of the main secondary charged particles produced by nuclear reactions", and the latter corresponds to "the product of the target organ dose information of the main secondary charged particles produced by nuclear reactions and their corresponding conversion coefficients". Numerically, "the product of the target organ dose information of the main secondary charged particles produced by nuclear reactions and their corresponding conversion coefficients" is equal to "the water dose information of the main secondary charged particles produced by nuclear reactions". In other words, when calculating the water dose of secondary fragments, corrections are made for the main secondary charged particles, that is, their organ doses are converted into water doses; no corrections are made for other secondary charged particles, and their organ doses are directly used as water doses. Through selective and targeted corrections, both high calculation efficiency and high calculation accuracy of the dose conversion process are taken into account.

[0216] Thus, the conversion relationship can be used to indicate the conversion coefficient of the dose deposition of secondary fragments between the target organ and water. First, a nuclear reaction information set is obtained to 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, the target organ dose information and the water dose information are calculated, and the dose deposition of secondary fragments in the target organ and water is calculated based on the nuclear reaction information set. This includes calculating the dose of secondary fragments in the target organ and the dose in the water to ensure that the dose conversion process is accurately captured. After that, the conversion coefficient is calculated, and the conversion coefficient of the dose deposition of secondary fragments between the target organ and water is calculated based on the dose information of the secondary fragments in the target organ and the water.

[0217] For the conversion coefficient of the dose deposition of the primary secondary charged particles between the target organ and water (i.e., the conversion coefficient corresponding to the primary secondary charged particles produced by nuclear reactions), first, the confinement stopping power value is calculated, and the confinement stopping power values ​​of the primary secondary charged particles in the target organ and water are calculated respectively according to the number of atoms per unit mass, the effective atomic number, and the average ionization energy of the target organ, the number of atoms per unit mass, the effective atomic number, and the average ionization energy of water, and the charge, speed, and energy threshold of the primary secondary charged particles. The confinement stopping power reflects the degree of energy loss of the particles in different media when they interact with the atoms of the material, that is, the magnitude of the energy loss of the particles when they interact with different media. Secondly, the conversion coefficient is calculated, and the conversion coefficient of the dose deposition of the primary secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary secondary charged particles in the target organ and water and the density of the target organ and water. In this way, the dose deposition of the primary 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 acquiring a set of nuclear reaction information and calculating conversion coefficients, the dose distribution of secondary fragments in target organs 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 secondary fragments between the lungs (target organ) and water. First, obtain a set of nuclear reaction information, including the lung dose information of primary particles deposited in situ when a nuclear reaction occurs in the lungs, the lung dose information of the main secondary charged particles produced by the nuclear reaction and their corresponding conversion coefficients, and the lung dose information of other secondary charged particles produced by the nuclear reaction except the main secondary charged particles. Secondly, based on the nuclear reaction information set, calculate the dose information of secondary fragments in the lungs and water. Afterwards, calculate the conversion coefficient of secondary fragments between the lungs and water based on the dose information of secondary fragments in the lungs and water.

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

[0220] The type and energy of the secondary fragments and the type of the target organ are input into a conversion coefficient model to obtain a conversion coefficient between the dose deposition of the secondary fragments on the target organ and water.

[0221] In a specific application scenario, the embodiment of the present application further provides a dosage conversion method, the method comprising:

[0222] Obtain CT data of the patient;

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

[0224] Simulating the transport process of each particle corresponding to proton therapy in the target organ of a real human body respectively, and calculating the target organ dose information of each particle after the transport process; the particles corresponding to proton therapy include primary particles, secondary electrons and secondary fragments;

[0225] Obtaining a 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, in which each combination of particle type and particle energy corresponds to a conversion coefficient;

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

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

[0228] The process of obtaining the conversion coefficient of the dose deposition of the primary particles between the target organ and water includes:

[0229] Obtaining an energy threshold for generating secondary electrons by ionization interaction according to the energy and / or dose statistical voxel size of the primary particles;

[0230] Calculating the confinement stopping power values ​​of the primary particles in the target organ and water, respectively, according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, the charge, the velocity, and the energy threshold of the primary particles;

[0231] The conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary particles in the target organ and water, and the densities of the target organ and water.

[0232] The process of obtaining the conversion coefficient of the dose deposition of the secondary electrons between the target organ and water includes:

[0233] Determining 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, the 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, average ionization energy of the target organ and water and the energy of the secondary electrons.

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

[0236] Acquire a nuclear reaction information set, the nuclear reaction information set including: target organ dose information of the primary particles deposited in situ when a nuclear reaction occurs in the target organ, target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles;

[0237] Calculating target organ dose information and water dose information of the secondary fragments according to the nuclear reaction information set;

[0238] Calculating a conversion coefficient between the target organ and water for the dose deposition of the secondary fragments according to the target organ dose information and the dose information in water of the secondary fragments;

[0239] The process of obtaining the conversion coefficient of the dose deposition of the primary secondary charged particles generated by the nuclear reaction 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] Calculating the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water respectively according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, and the charge, velocity, and the energy threshold of the primary and secondary charged particles;

[0241] The conversion coefficient of the dose deposition of the primary and secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water, and the densities of the target organ and water.

[0242] As an example, suppose that a conversion of organ dose to dose in water needs to be achieved.

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

[0244] Secondly, the conversion coefficient of each particle to different organs is calculated. According to the energy deposition mode of the interaction between protons, heavy ions and other particles and matter, the types of particles and energy information involved in the process are considered to generate specific conversion coefficients for each organ. For example, considering the particles and their energy deposition mode, the particles are divided into three types according to the type of physical interaction: 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, subscript j represents the jth organ, subscript w and m represent water and organ m, respectively. w and D m They represent the dose deposition of particles with energy E in water and organ m in different reaction processes respectively. The subscripts primary, electron, and nuclear represent primary particles, secondary electrons, and nuclear reactions respectively.

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

[0249] (1) Conversion of primary particle organ dose to water dose, which is based on the Bethe-bloch theory formula (reference information: Newhauser WD, Zhang R. The physics of proton therapy. Physics in medicine and biology. 2005; 60: R155-R209.), and is obtained by calculating the electron confinement stopping power ratio of primary particles in two materials (organ and water) (i.e., the ratio of the confinement stopping power of the two).

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

[0251]

[0252] Among them: [D w ] primary and [D m ]primary denote the dose deposition of primary particles in water and in organ m (i.e., the dose in water and the dose in organ of primary particles), respectively, ρ w and ρ m denote the densities of water and organ m, respectively. and are the restraining stopping power of primary particles in water and organ m, respectively, [s w,m (E)] primary The conversion coefficient of the primary particle dose deposition from organ m to water is related to the kinetic energy E of the primary particle, the elemental composition of organ m, the generation threshold Δ of secondary electrons (i.e., ω c , both are the same physical quantity).

[0253] Restraint and Stopping Power It can be expressed as:

[0254]

[0255] Where: r e is the classical electron radius, m e is the mass of the electron, c is the speed of light in a vacuum, The (capital letter) Z in the formula is the effective atomic number of the medium, μA is the number of atoms per unit mass of the medium, and “z 2 "The (lowercase letter) z is the charge of the primary incident particle (in units of electron charge). β = c / v, v is the velocity of the primary incident particle, I is the average ionization energy of the medium, ω c (ie, Δ) is the energy threshold for generating secondary electrons by ionization interaction, and the energy threshold may be, for example, a comprehensive consideration of factors such as the energy of the primary particles and the size of the dose recording voxel.

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

[0257] Since the energy threshold for generating secondary electrons is set, only electrons with kinetic energy higher than the threshold will be generated and tracked. Therefore, the correction of secondary electrons in the dose conversion method is only for these electrons.

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

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

[0260]

[0261] Among them: [D w ]electron and [D m ] electron denote the dose deposition of secondary electrons in water and in organs 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 average 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 ) is a constant related to electron energy but independent of dielectric material, and its value can be obtained from ICRU 37 report (reference information: ICRU Report 37. Stopping Powers for Electrons and Positrons. 1984.).

[0262] (3) Conversion of organ doses from nuclear reactions (corresponding to secondary fragments) to doses in water

[0263] When protons, heavy ions and other particles react with matter, primary particles are absorbed and secondary fragments are generated, and energy deposition occurs at the same time. The types of fragments and energy distribution generated by 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 take into account both calculation efficiency and accuracy, the secondary particles generated by the nuclear reaction are first screened, and the secondary particles that contribute more importantly to the calculation results (i.e., the main secondary charged particles) are selected, and only the dose deposition of these particles is converted, and the other particles (i.e., other secondary charged particles) directly use the dose in the organ instead of the dose in the water.

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

[0265]

[0266] Among them: [D w ] Nuclear represents the dose deposition of secondary fragments in water, that is, the water dose of secondary fragments; [D m ] Nuclear It represents the in-situ dose deposition in organ m when the primary particles undergo nuclear reaction; represents the dose deposition of the primary secondary charged particles produced by nuclear reactions in organ m (i.e., the organ dose of the primary secondary charged particles). These particles mainly lose energy through ionization interactions. The conversion coefficient Calculated by formula (2), no further explanation is given here; It represents the dose deposition in organ m (i.e. the organ dose of other secondary charged particles) of secondary charged particles (i.e. other secondary charged particles) produced by nuclear reactions excluding conversion, and its dose deposition in water is approximately equal to the dose deposition in organ m (i.e. the dose in water of other secondary charged particles is equal to the organ dose of other secondary charged particles).

[0267] Combined with the conversion coefficient calculation process corresponding to the primary particles, secondary electrons, and secondary fragments in (1) to (3) above, when calculating MC, first set the organ components (i.e., the elemental components of the organ) at the spatial position corresponding to each voxel according to the CT value information of the tissue site. According to the initial information such as the energy and angular distribution of the primary particles, (particle) tracking is performed on them, and the dose deposition of the particles in each organ is recorded (i.e., the organ dose of the particles for each organ is recorded). According to the information such as the organ type, the particle type, the physical reaction type between the particle and the organ, and the particle energy, the corresponding coefficient is found in the conversion coefficient table of the corresponding organ to 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 of the particle and the organ.

[0268] See also Figure 2 , Figure 2 This is a flow chart for converting an organ dose of a particle to an in-water dose provided in an embodiment of the present application.

[0269] As an example, the present application embodiment also provides a dosage conversion method, comprising the following steps:

[0270] Import CT data;

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

[0272] Particle tracking is performed using the MC algorithm to obtain the organ dose of each particle;

[0273] For each organ 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] The process of establishing the organ conversion coefficient table includes:

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

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

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

[0278] Therefore, the organ dose calculated by the Monte Carlo dose algorithm (i.e., MC algorithm) is converted into the dose in water, which involves the rapid conversion process of organ dose to dose in water in particle radiotherapy such as protons and heavy ions, while taking into account the classification and elemental composition of human organs in particle radiotherapy (i.e., particle radiotherapy).

[0279] Through the above-mentioned 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 ionization interaction, the constraint stopping power value corresponding to the energy threshold is used to calculate the conversion coefficient of the corresponding particle energy and organ. Secondly, the conversion of secondary electron dose deposition is considered. Taking into account the size of dose statistical voxels in clinical treatment, the energy of primary particles, and the range of electrons in different organs, a reasonable generation threshold (i.e., energy threshold) is selected, and the electrons with energy higher than the generation threshold are transported, and the dose deposition on the travel path is converted. Thirdly, for the nuclear reaction process, according to the type, yield, and contribution to the total dose of secondary fragments generated by the nuclear reaction, the types of fragments that have a greater impact on the results (i.e., the main secondary charged particles) are screened out, and their dose deposition is corrected; for fragments that do not significantly affect the calculation results (i.e., other secondary charged particles), their dose deposition in the organ is directly used as the water dose at the corresponding spatial position. In this way, we can achieve targeted results, ensure calculation efficiency, and maintain the accuracy of the results. In other words, the dose conversion method can take into account both higher computational efficiency and higher accuracy.

[0280] Moreover, the above-mentioned dose conversion method makes the establishment of conversion coefficients more accurate, systematic and complete. For example, by fully considering the differences in the elemental composition of human organs for gender and tissue location, using the model data of ICRP reference people or Chinese reference people, a set of systematic conversion coefficients can be established for different organs, particles of different energies and types.

[0281] In addition, the above dose conversion method has strong universality. In addition to being used for the conversion of proton, α and carbon ion doses from organ to water in clinical treatment, the above dose conversion method and conversion coefficient are also applicable to the conversion of heavy ions in other studies, such as O-16, Ne-20, Fe-56 and other heavy ions dose deposition in any material to dose deposition in water.

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

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

[0284] (Radiation Therapy System)

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

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

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

[0288] A dose conversion device, used to convert the target organ dose information of the particles into water dose information by using any of the above dose conversion methods;

[0289] The device for determining human body dose is used to determine the dose used in radiotherapy according to the expected dose information after the water dose information of the particles matches the expected dose information.

[0290] Radiotherapy systems are medical devices used to treat diseases such as cancer. Radiotherapy systems need to ensure that the dose distribution of particles in the patient's body meets the expected dose information set in the treatment plan. However, due to the characteristics of different tissues and media and the complexity of dose conversion, existing technologies often have difficulty in achieving accurate dose distribution.

[0291] Thus, the embodiment of the present application provides a radiotherapy system, which is intended to provide accurate 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 to the human anatomical structure, the mapping from the CT data to the real human body is realized, thereby 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 target organ dose information of the particles after the 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 uses one of the dose conversion methods provided above 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 expected dose information, and determine the dose used in radiotherapy according to the required treatment dose. By matching the dose in water with the expected dose, the radiotherapy plan can be adjusted to meet specific treatment needs. This radiotherapy system has the ability to accurately calculate and adjust dose distribution, which helps to improve the accuracy and safety of radiotherapy. It can provide support for doctors to develop personalized treatment plans, improve treatment effects and reduce the occurrence of side effects.

[0292] (Electronic equipment)

[0293] The embodiment of the present application also provides an electronic device, the specific embodiment of which is consistent with the embodiment recorded in the above method embodiment and the technical effects achieved, and some contents will not be repeated here.

[0294] The electronic device comprises 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:

[0295] Acquiring first material dosage information of particles;

[0296] Acquire a conversion relationship between the first material and the second material of the particle dose deposition;

[0297] According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage information.

[0298] According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage information.

[0299] In some embodiments, 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 particle corresponds to a conversion coefficient; or,

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

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

[0302] The particles are protons and / or heavy ions; or,

[0303] The particles are any charged particles.

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

[0305] The process of obtaining the first material dosage information of the particles includes:

[0306] Obtain CT data of the patient;

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

[0308] The transport process of the particles in the target organs of a real human body is simulated, and the target organ dose information after the particles have been transported is calculated.

[0309] In some embodiments, the conversion relationship is used to indicate a conversion coefficient between the dose deposition of the primary particles and water;

[0310] The process of obtaining the conversion coefficient between the dose deposition of the primary particles on the target organ and water comprises:

[0311] Obtaining an energy threshold for generating secondary electrons by ionization interaction according to the energy and / or dose statistical voxel size of the primary particles;

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

[0313] The conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the confinement 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 a conversion coefficient of the dose deposition of the secondary electrons between the target organ and water;

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

[0316] Determining whether the energy of the secondary electron is greater than the energy threshold;

[0317] When the energy of the secondary electrons is greater than the energy threshold, the 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, 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 a conversion coefficient between the dose deposition of the secondary fragments and water;

[0319] The process of acquiring the conversion coefficient between the dose deposition of the secondary fragments and the target organ and water comprises:

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

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

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

[0323] The process of obtaining the conversion coefficient of the dose deposition of the primary secondary charged particles generated by the nuclear reaction between the target organ and water includes:

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

[0325] The conversion coefficient of the dose deposition of the primary and secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water, and the densities of the target organ and water.

[0326] See also Figure 3 , Figure 3 It is a structural block diagram of an electronic device 10 provided in 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. The memory 11 also stores a computer program, which 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 also include a utility 114 having at least one program module 115, such program module 115 includes but is not limited to: an operating system, one or more application programs, other program modules and program data, each of which or some combination thereof may include the implementation of a network environment.

[0329] Accordingly, the processor 12 may execute the above-mentioned computer program and may execute the utility 114. The processor 12 may be implemented by 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 a local bus representing one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or any of a variety of bus architectures.

[0331] The electronic device 10 may also communicate with one or more external devices such as a keyboard, a pointing device, a Bluetooth device, etc., and may also communicate with one or more devices that can interact 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 may be performed through an input / output interface 14. In addition, the electronic device 10 may 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 a network adapter 15. The network adapter 15 may 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 may be used in conjunction with the electronic device 10 in actual applications, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0332] (Computer readable storage medium)

[0333] The embodiment of the present application also provides a computer-readable storage medium, the specific embodiment of which is consistent with the embodiment recorded in the above method embodiment and the technical effects achieved, and some contents will not be repeated here.

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

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

[0336] The computer-readable storage medium may include a data signal propagated in a baseband or as part of a carrier wave, wherein a readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer-readable storage medium may also be any computer-readable medium that can send, propagate, or transmit a program for use by an instruction execution system, an apparatus, or a device or used in combination with it. The program code contained on the computer-readable storage medium may be transmitted with any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above. The program code for performing the operation 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 a user computing device, partially on a user device, as a separate software package, partially on a user device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving 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 may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0337] (Computer Program Product)

[0338] The embodiment of the present application also provides a computer program product, the specific embodiments of which are consistent with the embodiments recorded in the above method embodiments and the technical effects achieved, and some contents will not be repeated here.

[0339] The present application provides a computer program product, which includes a computer program. When the computer program is executed by at least one processor, the steps of any of the above methods or the functions of any of the above electronic devices are implemented.

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

[0341] The computer program product is used to implement the steps of any of the above methods or to implement the functions of any of the above electronic devices. The computer program product may be a portable compact disk read-only memory (CD-ROM) and include 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 be any combination of one or more computer-readable media.

[0342] This application is explained 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 drawings of this application are only the preferred embodiments of this application, and are not intended to limit this application. Therefore, all structures, devices, features, etc. that are similar or identical to this application, that is, all equivalent replacements or modifications made in accordance with the scope of the patent application of this application, should fall within the scope of protection of the patent application of this application.

Claims

1. A dosage conversion method, characterized in that: The method comprises: Acquiring first material dosage information of particles; Acquire a conversion relationship between the first material and the second material of the particle dose deposition; According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage information.

2. The dosage conversion method according to claim 1, characterized in that: 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 particle corresponds to a conversion coefficient; or, The conversion relationship is represented by a conversion coefficient model.

3. The dosage conversion method according to claim 2, characterized in that: The particles include one or more of primary particles, secondary electrons and secondary fragments; or, The particles are protons and / or heavy ions; or, The particles are any charged particles.

4. The dosage conversion method according to claim 3, characterized in that: The first material dosage information is target organ dosage information, and the second material dosage information is water dosage information; The process of obtaining the first material dosage information of the particles includes: Obtain CT data of the patient; According to the CT value of each voxel in the CT data, each voxel is replaced with a corresponding real human organ material to achieve mapping from the CT data to the real human body; The transport process of the particles in the target organs of a real human body is simulated, and the target organ dose information after the particles have been transported is calculated.

5. The dosage conversion method according to claim 4, characterized in that: The conversion relationship is used to indicate the conversion coefficient between the dose deposition of the primary particles and water; The process of obtaining the conversion coefficient between the dose deposition of the primary particles on the target organ and water comprises: Obtaining an energy threshold for generating secondary electrons by ionization interaction according to the energy and / or dose statistical voxel size of the primary particles; Calculating the confinement stopping power values ​​of the primary particles in the target organ and water, respectively, according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, the charge, the velocity, and the energy threshold of the primary particles; The conversion coefficient of the dose deposition of the primary particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary particles in the target organ and water, and the densities of the target organ and water.

6. The dosage conversion method according to claim 5, characterized in that: The conversion relationship is used to indicate the conversion coefficient of the dose deposition of the secondary electrons between the target organ and water; The process of acquiring the conversion coefficient of the dose deposition of the secondary electrons between the target organ and water includes: Determining whether the energy of the secondary electron is greater than the energy threshold; When the energy of the secondary electrons is greater than the energy threshold, the 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, average ionization energy of the target organ and water and the energy of the secondary electrons.

7. The dosage conversion method according to claim 4, characterized in that: The conversion relationship is used to indicate the conversion coefficient between the dose deposition of the secondary fragments and water; The process of acquiring the conversion coefficient between the dose deposition of the secondary fragments and the target organ and water comprises: Acquire a nuclear reaction information set, the nuclear reaction information set including: target organ dose information of the primary particles deposited in situ when a nuclear reaction occurs in the target organ, target organ dose information of the main secondary charged particles generated by the nuclear reaction and their corresponding conversion coefficients, and target organ dose information of other secondary charged particles generated by the nuclear reaction except the main secondary charged particles; Calculating target organ dose information and water dose information of the secondary fragments according to the nuclear reaction information set; Calculating a conversion coefficient between the target organ and water for the dose deposition of the secondary fragments according to the target organ dose information and the water dose information of the secondary fragments; The process of obtaining the conversion coefficient of the dose deposition of the primary secondary charged particles generated by the nuclear reaction between the target organ and water includes: Calculating the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water respectively according to the number of atoms per unit mass, the effective atomic number, the average ionization energy of the target organ and water, and the charge, velocity, and the energy threshold of the primary and secondary charged particles; The conversion coefficient of the dose deposition of the primary and secondary charged particles between the target organ and water is calculated according to the confinement stopping power values ​​of the primary and secondary charged particles in the target organ and water, and the densities of the target organ and water.

8. An electronic device, characterized in that: The electronic device comprises 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: Acquiring first material dosage information of particles; Acquire a conversion relationship between the first material and the second material of the particle dose deposition; According to the conversion relationship, the first material dosage information of the particles is converted into second material dosage information.

9. 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, the computer program implements the steps of the method according to any one of claims 1 to 7 or implements the functions of the electronic device according to claim 8.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by at least one processor, the steps of the method according to any one of claims 1 to 7 or the functions of the electronic device according to claim 8 are implemented.

11. A radiotherapy system, characterized in that: include: A mapping device for acquiring CT data of a patient; According to the CT value of each voxel in the CT data, each voxel is replaced with a corresponding real human organ material to achieve mapping from the CT data to the real human body; A device for simulating particle transport, used to simulate the transport process of particles in target organs of a real human body and calculate the target organ dose information of the particles after the transport process; A dose conversion device, used to convert the target organ dose information of the particles into water dose information by using the dose conversion method according to any one of claims 1 to 7; The device for determining human body dose is used to determine the dose used in radiotherapy according to the expected dose information after the water dose information of the particles matches the expected dose information.

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