Radiation source modeling system and method

Abstract

The present disclosure provides a system and method for determining a target multi-source model of a radiation source corresponding to an energy spectrum. The system can obtain an initial multi-source model of a radiation source, the initial multi-source model including an initial phase space file, the initial phase space file including information of multiple simulated particles of different energies. The system can calculate different energy PDD curves in a phantom based on the initial phase space file. The system can obtain a measured PDD curve corresponding to the radiation of the energy spectrum. For each energy, the system can determine the weight of each energy based on the different energy PDD curves and the measured PDD curve. The system can determine the target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model and the weights.

Description

Technical Field

[0001] The present specification relates to a radiation device, and more particularly to a modeling system and method for a radiation source of a radiation device. Background Art

[0002] Radiotherapy using a radiation source (e.g., an electron linear accelerator) is a known treatment method for various tumors (e.g., nasopharyngeal carcinoma, breast cancer, or skin cancer). The radiation source may need to provide a sufficient and accurate radiation dose to a region of interest (e.g., a tumor) of an object (e.g., a patient), and avoid radiation to other areas of the object (e.g., normal organs or tissues) as much as possible. In modern radiotherapy practice, a treatment planning system (TPS) can be used to predict the dose distribution of radiation from a radiation source in an object using a Monte Carlo algorithm. The key to the Monte Carlo algorithm is to construct a virtual source model to model the radiation source. However, the current modeling process may need to consider multiple virtual source types, requires a large amount of measurement data, and is complex and time-consuming. Therefore, it is necessary to develop an effective system and method for simulating radiation sources to improve the accuracy of determining the radiation dose distribution of the radiation source in the patient. Summary of the invention

[0003] According to one aspect of the present disclosure, a system is provided. The system may include at least one storage device, the storage device including a set of instructions for modeling a radiation source configured to emit energy spectrum radiation containing different energies. The system may also include at least one processor in communication with the storage device. When executing the instructions, the at least one processor may be configured to cause the system to perform the following operations, including: obtaining an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, and the initial phase space file includes information of multiple simulated particles of different energies; based on the initial phase space file, calculating different energy percentage depth dose (PDD) curves in the phantom, wherein each of the different energy PDD curves corresponds to an energy; obtaining a measured PDD curve corresponding to the radiation of the energy spectrum passing through the phantom in the phantom; for each energy in the different energies, based on the different energy PDD curves and the measured PDD curves, determining the weight of each energy, the weight representing the percentage of simulated particles of each energy in the multiple simulated particles present in the radiation; and determining a target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model and the weight.

[0004] In some embodiments, the initial phase space file includes a set of initial weights, wherein each initial weight corresponds to one of the different energies. To determine the weight of each of the different energies, at least one processor may also be configured to cause the system to perform operations including: determining a composite PDD curve based on the different energy PDD curves by adjusting at least one of the initial weights until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold; and determining the weight of each of the different energies based on the adjusted weights.

[0005] In some embodiments, the radiation source includes a primary source and an electronic light-limiting tube. The radiation includes primary electrons and secondary electrons. The primary electrons are generated by the primary source. The primary electrons include a first portion and a second portion, and the first portion of the primary electrons leave the radiation source without being scattered. The secondary electrons are generated by the second portion of the primary electrons hitting the electronic light-limiting tube.

[0006] In some embodiments, the first portion of the simulated particles corresponds to a first portion of the primary electrons.

[0007] In some embodiments, the radiation further comprises photons. The second portion of the simulated particles corresponds to the photons.

[0008] In some embodiments, the photons are generated by a primary source.

[0009] In some embodiments, the initial multi-source model of the radiation source includes a master virtual source for simulating a master source, the master virtual source corresponding to a first portion of simulated particles and a second portion of simulated particles.

[0010] In some embodiments, the primary virtual source may be a point source.

[0011] In some embodiments, the initial phase space file includes a position of a first portion of simulated particles and an orientation of the first portion of simulated particles.

[0012] In some embodiments, the position of the first portion of simulated particles or the direction of the first portion of simulated particles is determined based on direct sampling of the first distribution function. The particle flux distribution of the first portion of simulated particles on a plane perpendicular to the axis of the main virtual source conforms to the first distribution function.

[0013] In some embodiments, the first distribution function is a first Gaussian function.

[0014] In some embodiments, a third portion of the simulated particles corresponds to secondary electrons, and the initial multi-source model of the radiation source includes a secondary virtual source for simulating an electron confining cylinder, the secondary virtual source corresponding to the third portion of the simulated particles.

[0015] In some embodiments, the secondary virtual source includes at least one of a second point source or an area source.

[0016] In some embodiments, the initial phase space file includes a position of the third portion of the simulated particle and an orientation of the third portion of the simulated particle.

[0017] In some embodiments, the third portion of the simulated particles includes a first sub-portion of the simulated particles corresponding to the second point source and a second sub-portion of the simulated particles corresponding to the surface source. The position of the first sub-portion of the simulated particles or the direction of the first sub-portion of the simulated particles is determined based on a second direct sampling of the second distribution function. The particle flux distribution of the first sub-portion of the simulated particles on a second plane perpendicular to the axis of the main virtual source conforms to the second distribution function. The position of the second sub-portion of the simulated particles or the direction of the second sub-portion of the simulated particles is determined based on a third direct sampling of the third distribution function. The particle flux distribution of the second sub-portion of the simulated particles on a third plane perpendicular to the axis of the main virtual source conforms to the third distribution function.

[0018] In some embodiments, the second distribution function is a second Gaussian function, and the third distribution function is a uniform distribution function.

[0019] In some embodiments, at least one processor can be further configured to cause the system to perform operations including: obtaining a measured off-axis ratio (OAR) curve corresponding to radiation of an energy spectrum passing through a phantom; determining a simulated OAR curve in the phantom based on master virtual source parameters of an initial multi-source model and an initial phase space file; adjusting the master virtual source parameters until a second difference between a penumbra region of the simulated OAR curve and a penumbra region of the measured OAR curve is lower than a second threshold; and further determining a target multi-source model of the radiation source based on the adjustment of the master virtual source parameters.

[0020] In some embodiments, the master virtual source parameters include at least one of a size of the master virtual source, a vertical position of the master virtual source along an axis of the master virtual source, or a particle flux distribution of the master virtual source.

[0021] In some embodiments, the main source is configured to be operably coupled to one of a plurality of second electronic light limiting cylinders, and the at least one processor is further configured to cause the system to perform operations including: for each of the plurality of second electronic light limiting cylinders, obtaining an output factor corresponding to the second electronic light limiting cylinder; based on structural parameters of the second electronic light limiting cylinder, determining a simulated output factor corresponding to the second electronic light limiting cylinder; and determining a correction coefficient of the second electronic light limiting cylinder based on the output factor and the simulated output factor.

[0022] In some embodiments, a weight for each of the different energies is determined, and at least one processor is further configured to cause the system to perform operations including: receiving user input related to the weight of the energy; and determining the weight of the energy based at least in part on the user input.

[0023] In some embodiments, the radiation source is a linear accelerator.

[0024] In some embodiments, at least one processor is further configured to cause the system to perform operations including: calculating the average energy of photons based on energy; determining the measured average energy of photons based on a measured PDD curve; determining the weight of the photons based on the calculated average energy and the measured average energy; and further determining a target multi-source model based on the weight of the photons.

[0025] In some embodiments, the electronic light limiting tube includes at least an upper portion, a middle portion and a lower portion. The second point source corresponds to the upper portion and the middle portion of the electronic light limiting tube, and the surface source corresponds to the lower portion of the electronic light limiting tube.

[0026] In some embodiments, the radiation source includes a collimation assembly. The initial multi-source model of the radiation source also includes a third virtual source corresponding to the collimation assembly.

[0027] In some embodiments, the third virtual source is a line source.

[0028] According to another aspect of the present disclosure, a system is provided. The system may include at least one storage device storing a set of instructions for determining a dose distribution in an object irradiated with an energy spectrum from a radiation source. The radiation source includes a main source and an electronic light-limiting cylinder. The system may also include at least one processor in communication with the storage device. When executing the instructions, the at least one processor may be configured to cause the system to perform operations including: obtaining structural parameters of the electronic light-limiting cylinder; obtaining a target multi-source model of the radiation source corresponding to the energy spectrum; based on the target multi-source model and the structural parameters of the electronic light-limiting cylinder, determining a phase space file containing information of multiple simulated particles corresponding to the radiation; obtaining a transmission model of the radiation of the energy spectrum passing through the object; and determining the dose distribution in the object based on the phase space file and the transmission model.

[0029] In some embodiments, the target multi-source model may include a master virtual source corresponding to a primary source, the master virtual source being a first point source.

[0030] In some embodiments, the target multi-source model of the radiation source may include a secondary virtual source corresponding to the electronic light limiting cylinder. The secondary virtual source includes a second point source and a surface source.

[0031] In some embodiments, the electronic light limiting tube includes at least an upper portion, a middle portion, and a lower portion. The second point source corresponds to the upper portion and the middle portion of the electronic light limiting tube. The surface source corresponds to the lower portion of the electronic light limiting tube.

[0032] In some embodiments, the radiation includes primary electrons, photons and secondary electrons. The primary electrons and photons are generated by a primary source. The primary electrons include a first portion and a second portion, and the first portion leaves the radiation source without being scattered. The secondary electrons are generated by the second portion of the primary electrons hitting the electronic light limiting cylinder.

[0033] In some embodiments, a first portion of the simulated particles corresponds to a first portion of the primary electrons. A second portion of the simulated particles corresponds to photons. A third portion of the simulated particles corresponds to secondary electrons.

[0034] In some embodiments, the phase space file includes at least one of a position, an orientation, or an energy of each of the plurality of simulated particles.

[0035] In some embodiments, the position, orientation, or energy of each of the plurality of simulated particles is determined based on direct sampling.

[0036] In some embodiments, for each of the first portion of simulated particles, at least one processor is further configured to cause the system to perform the following operations, including: determining the position or direction of the simulated particle through a first direct sampling based on a first distribution function, wherein a particle flux distribution of the first portion of the simulated particles on a plane perpendicular to the axis of the main virtual source conforms to the first distribution function; and determining the particle energy of the simulated particle through a second direct sampling of the energy spectrum based on a target multi-source model.

[0037] In some embodiments, the first distribution function may be a first Gaussian function.

[0038] In some embodiments, the second portion of simulated particles includes a first sub-portion of simulated particles corresponding to the second point source and a second sub-portion of simulated particles corresponding to the area source.

[0039] In some embodiments, for each of the first sub-portions of simulated particles, at least one processor is further configured to cause the system to perform operations including: determining the position or direction of the simulated particle by third direct sampling based on the second distribution function, wherein the particle flux distribution of the first sub-portion of simulated particles on a second plane perpendicular to the axis of the main virtual source conforms to the second distribution function. Determining the particle energy of the simulated particle by fourth direct sampling of the energy spectrum based on the target multi-source model.

[0040] In some embodiments, the second distribution function is a second Gaussian function.

[0041] In some embodiments, for each of the second sub-portions of simulated particles, at least one processor is further configured to cause the system to perform operations including: determining the position or direction of the simulated particle by fifth direct sampling based on the third distribution function, wherein the particle flux distribution of the second sub-portion of the simulated particles on a plane perpendicular to the axis of the main virtual source conforms to the third distribution function. Determining the particle energy of the simulated particle by sixth direct sampling of the energy spectrum based on the target multi-source model.

[0042] In some embodiments, at least one of the third distribution functions is a uniform distribution function.

[0043] In some embodiments, the radiation source includes a collimation component, and the target multi-source model of the radiation source further includes a third virtual source corresponding to the collimation component, and the third virtual source is a line source.

[0044] In some embodiments, the radiation source is a linear accelerator.

[0045] According to another aspect of the present disclosure, a method for modeling a radiation source is provided, the radiation source being configured to emit radiation including an energy spectrum of different energies. The method may be implemented on a computing device including at least one processor and at least one storage device. The method may include obtaining an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, the initial phase space file including information of multiple simulated particles of different energies; based on the initial phase space file, calculating different energy percentage depth dose (PDD) curves in a phantom, wherein each of the different energy PDD curves corresponds to one of the different energies; obtaining a measured PDD curve in the phantom corresponding to the radiation of the energy spectrum passing through the phantom; for each of the different energies, based on the different energy PDD curves and the measured PDD curves, determining a weight for each energy, the weight representing the percentage of simulated particles of each energy in the multiple simulated particles present in the radiation; and determining a target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model and the weight.

[0046] According to another aspect of the present disclosure, a method for determining a dose distribution in an object subjected to radiation of an energy spectrum from a radiation source is provided. The radiation source includes a main source and an electronic light-limiting cylinder. The method can be implemented on a computing device including at least one processor and at least one storage device. The method may include obtaining structural parameters of the electronic light-limiting cylinder; obtaining a target multi-source model of the radiation source corresponding to the energy spectrum; determining a phase space file containing information of a plurality of simulated particles corresponding to the radiation based on the target multi-source model and the structural parameters of the electronic light-limiting cylinder; obtaining a transmission model of the radiation of the energy spectrum passing through the object; and determining the dose distribution in the object based on the phase space file and the transmission model.

[0047] According to another aspect of the present disclosure, a system for modeling a radiation source is provided, the radiation source being configured to emit radiation including an energy spectrum of different energies. The system may include an acquisition module, a calculation module, and a determination module. The acquisition module is used to acquire an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, the initial phase space file includes information of multiple simulated particles of different energies, and is used to acquire a measured PDD curve corresponding to the radiation of the energy spectrum passing through the phantom in the phantom. The calculation module is used to calculate different energy percentage depth dose (PDD) curves in the phantom based on the initial phase space file, wherein each of the different energy PDD curves corresponds to an energy. The determination module is used to determine the weight of each energy for each of the different energies based on the different energy PDD curves and the measured PDD curve, the weight representing the percentage of simulated particles of each energy in the multiple simulated particles present in the radiation, and is used to determine the target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model and the weight.

[0048] According to another aspect of the present disclosure, a system for determining a dose distribution in an object subjected to radiation of an energy spectrum from a radiation source is provided. The radiation source includes a main source and an electronic light-limiting cylinder. The system may include an acquisition module and a determination module. The acquisition module is used to acquire structural parameters of the electronic light-limiting cylinder, acquire a target multi-source model of the radiation source corresponding to the energy spectrum, and acquire a transmission model of the radiation of the energy spectrum passing through the object. The determination module is used to determine a phase space file containing multiple simulated particle information corresponding to the radiation based on the target multi-source model and the structural parameters of the electronic light-limiting cylinder, and determine the dose distribution in the object based on the phase space file and the transmission model.

[0049] According to another aspect of the present disclosure, a non-transitory computer-readable medium is provided, comprising at least one set of instructions, wherein when executed by at least one processor of a computing device, the at least one set of instructions instructs the at least one processor to perform a method for simulating a radiation source, the radiation source being configured to emit radiation including a spectrum of different energies. The method may include: obtaining an initial multi-source model of the radiation source, wherein the initial multi-source model comprises an initial phase space file, the initial phase space file comprising information of a plurality of simulated particles of different energies; based on the initial phase space file, calculating a different energy percentage depth dose (PDD) curve in a phantom, wherein each of the different energy PDD curves corresponds to an energy; obtaining a measured PDD curve corresponding to radiation of the energy spectrum passing through the phantom in the phantom; for each of the different energies, determining a weight for each energy based on the different energy PDD curve and the measured PDD curve, the weight representing the percentage of simulated particles of each energy among the plurality of simulated particles present in the radiation; and determining a target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model and the weight.

[0050] According to another aspect of the present disclosure, a non-transitory computer-readable medium is provided, comprising at least one set of instructions, wherein when executed by at least one processor of a computing device, the at least one set of instructions instructs the at least one processor to perform a method for determining a dose distribution in an object subjected to radiation of an energy spectrum from a radiation source. The method may include: obtaining structural parameters of an electronic light-limiting cylinder; obtaining a target multi-source model corresponding to the radiation source of the energy spectrum; determining a phase space file containing information of a plurality of simulated particles corresponding to the radiation based on the target multi-source model and the structural parameters of the electronic light-limiting cylinder; obtaining a transmission model of the radiation of the energy spectrum passing through the object; and determining the dose distribution in the object based on the phase space file and the transmission model.

[0051] Some additional features of the present application may be explained in the following description. Some additional features of the present application will be apparent to those skilled in the art through study of the following description and corresponding drawings or understanding of the production or operation of the embodiments. The features of the present application may be realized and achieved through practice or use of the methods, means and combinations of various aspects of the specific embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] This specification will be further described in the form of exemplary embodiments, which will be described in detail by the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0053] Figure 1 is an exemplary schematic diagram of a medical system according to some embodiments of the present disclosure;

[0054] Figure 2 is an exemplary schematic diagram of exemplary hardware and / or software components of a computing device according to some embodiments of the present disclosure;

[0055] Figure 3 is an exemplary schematic diagram of exemplary hardware and / or software components of a mobile device according to some embodiments of the present disclosure;

[0056] Figure 4 is a schematic diagram of an exemplary radiation source of treatment head 113 according to some embodiments of the present disclosure;

[0057] Figure 5A is a block diagram of an exemplary processing device according to some embodiments of the present disclosure;

[0058] Figure 5B is a block diagram of an exemplary processing device according to some embodiments of the present disclosure;

[0059] Figure 6is a flow chart of an exemplary process for modeling a radiation source according to some embodiments of the present disclosure;

[0060] Figure 7 A schematic diagram of exemplary virtual sources of an initial multi-source model of radiation sources according to some embodiments of the present disclosure;

[0061] Figure 8 is a flow chart of an exemplary process for determining a weight from each of different energies of an energy spectrum of a radiation source according to some embodiments of the present disclosure;

[0062] Fig. 9 is a schematic diagram 900 of an exemplary measured PDD curve and a corresponding composite PDD curve according to some embodiments of the present disclosure;

[0063] Fig.10 is an exemplary flow chart for determining parameters of a primary virtual source of a target multi-source model according to some embodiments of the present disclosure;

[0064] Fig.11 is a flow chart of an exemplary process for determining a correction factor corresponding to an electronic condenser according to some embodiments of the present disclosure;

[0065] Fig.12 is a flow chart of an exemplary process for determining a dose distribution in a subject according to some embodiments of the present disclosure;

[0066] Fig.13 is a flow chart of an exemplary process for determining a phase space file of a target multi-source model according to some embodiments of the present disclosure;

[0067] Fig.14 is a schematic diagram of an example dose distribution curve in a phantom according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. However, it should be understood by those skilled in the art that the present application can be implemented without these details. In other cases, in order to avoid unnecessarily obscuring the various aspects of the present application, well-known methods, processes, systems, components and / or circuits have been described at a higher level. For those of ordinary skill in the art, it is obvious that various changes can be made to the disclosed embodiments, and without departing from the principles and scope of the present application, the general principles defined in the present application can be applied to other embodiments and application scenarios. Therefore, the present application is not limited to the embodiments shown, but conforms to the broadest scope consistent with the scope of the application.

[0069] The terms used in this specification are only used for the purpose of describing specific exemplary embodiments and do not limit the scope of this specification. The singular forms "one", "an" and "the" used in this specification may also include plural forms, unless the context clearly indicates an exception. The terms "and / or" and "at least one of them" used in this specification include any and all combinations of one or more related listed items. It should also be understood that, as in the specification of this application, the terms "include" and / or "comprise" only indicate the presence of the features, wholes, steps, operations, components and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, components, parts and / or their combinations. In addition, "exemplary" refers to an example or illustration.

[0070] It should be understood that the terms "system", "unit", "module" and / or "block" used in this specification are methods for distinguishing different components, elements, parts, portions or assemblies at different levels in ascending order. However, if these terms achieve the same purpose, they may be replaced by another term.

[0071] Generally, the terms "module," "unit," or "block" as used herein refer to logic embodied in hardware or firmware, or a collection of software instructions. The modules, units, or blocks described herein may be implemented as software and / or hardware, and may be stored in any type of non-transitory computer-readable medium or other storage device. In some embodiments, software modules / units / blocks may be compiled and linked into an executable program. It should be understood that software modules may be called from other modules / units / blocks or from themselves, and / or may be called in response to detected events or interrupts. A software module / unit / block configured for execution on a computing device (e.g., Figure 2The processor 210 shown) can be provided on a computer-readable medium, such as a compact disc, a digital video disc, a flash drive, a disk, or any other tangible medium, or as a digital download (and can be initially stored in a compressed or installable format, which needs to be installed, decompressed, or decrypted before execution). The software code here can be stored in part or in whole in a storage device of a computing device that performs the operation and applied in the operation of the computing device. Software instructions can be embedded in firmware, such as an erasable programmable read-only memory (EPROM). It should also be understood that hardware modules / units / blocks can include connected logical components, such as gates and triggers, and / or can include programmable units, such as programmable gate arrays or processors. The modules / units / blocks or computing device functions described here can be implemented as software modules / units / blocks, but can be represented by hardware or firmware. Generally, the modules / units / blocks described here refer to logical modules / units / blocks, which can be combined with other modules / units / blocks or divided into sub-modules / sub-units / sub-blocks, regardless of their physical organization or storage. The present application can be applied to a system, an engine, or a part thereof.

[0072] It is understood that, unless the context clearly indicates otherwise, when a unit, engine, module or block is referred to as being "connected," "connected," or "coupled" to another unit, engine, module or block, it may be directly connected, connected, coupled or communicate with another unit, engine, module or block, or there may be an intermediate unit, engine, module or block, unless the context clearly indicates otherwise. In this application, the term "and / or" includes one or more of the related listed items or combinations.

[0073] These and other features, characteristics and functions and methods of operation of the related structural elements of the present application, as well as the combination of components and manufacturing economy, may become more apparent from the following description of the accompanying drawings, which form a part of the specification of this application. However, it should be understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of the present application. It should be understood that the drawings are not drawn to scale.

[0074] The term "modality" as used herein refers broadly to the imaging or therapeutic methods or techniques for collecting, generating, processing and / or analyzing imaging information of a subject or treating a subject. The subject may include biological objects and / or non-biological objects. The biological object may be a human, an animal, a plant, or a part thereof (e.g., a cell, a tissue, an organ, etc.). In some embodiments, the object may be an artificial composition of organic and / or inorganic matter with or without life. The terms "object" or "subject" are used interchangeably in this disclosure.

[0075] The term "image" in the present disclosure is used to collectively refer to image data (e.g., scan data, projection data) and / or various forms of images, including two-dimensional (2D) images, three-dimensional (3D) images, four-dimensional (4D) images, etc. The terms "pixel" and "voxel" are used interchangeably in the present disclosure to refer to elements of an image. The terms "region", "position" and "range" in the present disclosure may refer to the location of an anatomical structure displayed in an image, or the actual location of an anatomical structure present in or on the body of a target subject, because an image may indicate the actual location of a specific anatomical structure present in or on the body of a target subject. In some embodiments, an image of an object may be referred to as an object. Segmentation of an image of an object may be referred to as segmentation of the object. For example, organ segmentation refers to segmenting the region corresponding to an organ in an image.

[0076] The present disclosure provides a mechanism (which may include methods, systems, computer-readable media, etc.) for modeling radiation sources. The method may include obtaining an initial multi-source model of a radiation source. The radiation source may be configured to emit energy spectrum radiation containing different energies. The initial multi-source model may include an initial phase space file, which includes information of multiple simulated particles of different energies. The method may also include determining the weight of each energy in the different energies based on a plurality of calculated percentage depth dose (PDD) curves corresponding to different energies in a phantom and a measured PDD curve in a phantom corresponding to the radiation of the energy spectrum passing through the phantom. The method may also include determining the parameters of the main virtual source of the initial multi-source model based on the simulated off-axis ratio (OAR) curve and the measured OAR curve corresponding to the radiation of the energy spectrum passing through the phantom. The method may also include determining the correction coefficient of an electronic light-limiting cylinder operably coupled to the main source. These methods may also include determining the target multi-source model based on the initial multi-source model, the weights, the parameters of the main virtual source, and the correction coefficients.

[0077] The present disclosure also provides a mechanism (which may include methods, systems, computer-readable media, etc.) for determining a dose distribution in an object subjected to energy spectrum radiation from a radiation source. The method may include obtaining structural parameters of an electronic light-limiting cylinder of the radiation source, a target multi-source model of the corresponding energy spectrum of the radiation source, and a transmission model of the energy spectrum radiation passing through the object. The method may also include determining a phase space file containing information of a plurality of simulated particles corresponding to the radiation of the radiation source based on the target multi-source model and the structural parameters of the electronic light-limiting cylinder. The method may also include determining a dose distribution in the object based on the phase space file and the transmission model.

[0078] According to some embodiments of the present disclosure, the target multi-source model may include a main virtual source for simulating a main source and a secondary virtual source for simulating an electronic light-limiting cylinder, thereby reducing the number of virtual sources when simulating a radiation source. In the modeling process, only the parameters of the main virtual source need to be adjusted and the parameters of the secondary virtual source need to be determined according to the structural parameters of the corresponding electronic light-limiting cylinder, thereby reducing the complexity of the modeling process. In some embodiments, an energy spectrum corresponding to a specific energy setting of the radiation source can be calculated based on a reference electronic light-limiting cylinder; when the radiation source includes one of various electronic light-limiting cylinders other than the reference electronic light-limiting cylinder, the calculated energy spectrum can be used to determine the multi-source model of the radiation source for a specific energy setting, thereby avoiding the need to repeatedly calculate the energy spectrum for each different electronic light-limiting cylinder for the same energy setting of the radiation source, thereby reducing the amount of calculation in the modeling process and improving the efficiency of the modeling process. In some embodiments, for each of the different configurations of the radiation source (e.g., various electronic light-limiting cylinders), instead of predetermining and storing the phase space file containing the simulated scattered particle information in a storage device, the positions and directions of multiple simulated particles can be determined based on direct sampling during the modeling process, thereby reducing the storage space used to store the target multi-source model phase space file. In addition, the target multi-source model of the radiation source can also be applied to determine the dose distribution in the object irradiated with the energy spectrum from the radiation source, thereby improving the efficiency and accuracy of dose distribution estimation.

[0079] Figure 1 is an exemplary schematic diagram of a medical system according to some embodiments of the present disclosure. The medical system may utilize a radiation source for non-invasive imaging and / or treatment, for example, for disease diagnosis, treatment or research purposes. In some embodiments, the medical system may include a single-modality system or a multi-modality system. A single-modality system may include, for example, a radiation therapy (RT) device, an X-ray imaging system, a computed tomography (CT) system, a single photon emission computed tomography (SPECT) system, a digital radiography (DR) system, or any combination thereof. A multi-modality system may include, for example, an image-guided radiation therapy (IGRT) system (e.g., a CT-guided radiation therapy system, and a magnetic resonance imaging (MRI)-guided radiation therapy system), an X-ray imaging-MRI (X-ray-MRI) system, a SPECT-MRI system, a CT-positron emission tomography (CT-PET) system, and the like. It should be noted that the medical system described below is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. The following description will be based on Figure 1 The medical system shown is provided as a RT system for reference. It should be understood that this is for illustration purposes only and is not intended to limit the present description.

[0080] like Figure 1As shown, the medical system 100 may include a medical device 110, a network 120, one or more terminals 130, a processing device 140, and a storage device 150. In some embodiments, two or more components of the medical system 100 may be interconnected and / or communicate with each other via a wireless connection (e.g., the network 120), a wired connection, or a combination thereof. The connections between the components of the medical system 100 may be variable. By way of example only, the medical device 110 may be connected to the processing device 140 via the network 120 or directly. As a further example, the storage device 150 may be connected to the processing device 140 via the network 120 or directly connected to the processing device 140.

[0081] The medical device 110 may be configured to perform radiation therapy on an object (e.g., a patient or a portion thereof). For example, the medical device 110 may be a treatment device including a gantry 111, a table 112, a treatment head 113, and the like. The gantry 111 may be configured to provide support for other components of the medical device 110 (e.g., the treatment head 113). The table 112 may be configured to support the object and move it to a desired position (e.g., a treatment position under the treatment head 113 for treatment). The treatment head 113 may include a radiation source configured to emit therapeutic radiation to the object for treatment. For purposes of illustration, the radiation source of the treatment head 113 may be a linear accelerator, which is not limited in this specification. More description of the treatment head 113 may be found elsewhere in this disclosure (e.g., Figure 4 In some embodiments, the medical device 110 may include a cylinder rather than a frame 111 to provide support for the treatment head 113.

[0082] The network 120 may include any suitable network that can facilitate information and / or data exchange of the medical system 100. In some embodiments, one or more components of the medical system 100 (e.g., the medical device 110, the processing device 140, the storage device 150, the terminal 130) may communicate information and / or data with one or more other components of the medical system 100 via the network 120. For example, the processing device 140 may obtain image data from the medical device 110 via the network 120. As another example, the processing device 140 may obtain user instructions from the terminal 130 via the network 120. The network 120 may be or include a public network (e.g., the Internet), a private network (e.g., a local area network (LAN)), a wired network, a wireless network (e.g., an 802.11 network, a Wi-Fi network), a frame relay network, a virtual private network (VPN), a satellite network, a telephone network, a router, a hub, a switch, a server computer, and / or any combination thereof. For example, the network 120 may include a cable network, a wired network, a fiber optic network, a telecommunication network, an intranet, a wireless local area network (WLAN), a metropolitan area network (MAN), a public switched telephone network (PSTN), a Bluetooth TM Network, ZigBee TM Network, near field communication (NFC) network, etc. or any combination thereof. In some embodiments, network 120 may include one or more network access points. For example, network 120 may include wired and / or wireless network access points, such as base stations and / or Internet exchange points, through which one or more components of medical system 100 can connect to network 120 to exchange data and / or information.

[0083] The terminal 130 may be connected to and / or communicate with the medical device 110, the processing device 140, and / or the storage device 150. For example, the terminal 130 may obtain the dose distribution of the object from the processing device 140. As another example, the terminal 130 may enable the user to interact with the medical system 100. In some embodiments, the terminal 130 may include a mobile device 131, a tablet computer 132, a laptop computer 133, or any combination thereof. For example, the mobile device 131 may include a mobile phone, a personal digital assistant (PDA), a gaming device, a navigation device, a point of sale (POS) device, a laptop computer, a tablet computer, a desktop computer, or the like, or any combination thereof. In some embodiments, the terminal 130 may include an input device, an output device, and the like. The input device may include alphanumeric and other keys that may be input via a keyboard, a touch screen (e.g., with tactile or haptic feedback), voice input, eye tracking input, a brain monitoring system, or any other similar input mechanism. The input information received by the input device may be transmitted to the processing device 140 via, for example, a bus for further processing. Other types of input devices may include cursor control devices, such as a mouse, a trackball, or cursor direction keys. The output device may include a display, a speaker, a printer, etc., or a combination thereof. In some embodiments, the terminal 130 may be part of the processing device 140 .

[0084] The processing device 140 may process data and / or information obtained from the medical device 110, the storage device 150, the terminal 130, or other components of the medical system 100. For example, the processing device 140 may determine a target multi-source model corresponding to the energy spectrum of the radiation source based on the initial multi-source model, the different energy PDD curves in the phantom, and the measured PDD curves in the phantom corresponding to the energy spectrum radiation passing through the phantom. As another example, the processing device 140 may determine the dose distribution in the object irradiated with the energy spectrum from the radiation source based on the target multi-source model and the structural parameters of the electronic light limiting cylinder operably coupled to the radiation source. In some embodiments, the processing device 140 may be a single server or a server group. The server group may be centralized or distributed. In some embodiments, the processing device 140 may be locally connected to the medical system 100 or remotely connected to the medical system 100. For example, the processing device 140 may access information and / or data from the medical device 110, the storage device 150, and / or the terminal 130 through the network 120. As another example, the processing device 140 can be directly connected to the medical device 110, the terminal 130 and / or the storage device 150 to access information and / or data. In some embodiments, the processing device 140 can be implemented on a cloud platform. For example, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, a cross-cloud, a multi-cloud, or any combination thereof. In some embodiments, the processing device 140 can be composed of a computer system including a computer system that combines the computer system with the computer system. Figure 2 One or more of the components described may be implemented by the computing device 200 .

[0085] The storage device 150 may store data, instructions, and / or any other information. In some embodiments, the storage device 150 may store data obtained from the processing device 140, the terminal 130, and / or the storage device 150. In some embodiments, the storage device 150 may store data and / or instructions that the processing device 140 may execute or use to execute the exemplary methods described in the present disclosure. In some embodiments, the storage device 150 may include a mass storage device, a removable storage device, a volatile read-write memory, a read-only memory (ROM), or the like, or any combination thereof. Exemplary removable memory may include a flash drive, a floppy disk, an optical disk, a memory card, a compressed disk, a tape, and the like. Exemplary volatile read-write memory may include a random access memory (RAM). Exemplary RAM may include a dynamic random access memory (DRAM), a double data rate synchronous dynamic random access memory (DDRSDRAM), a static random access memory (SRAM), a thyristor random access memory (T-RAM), a zero capacitance random access memory (Z-RAM), and the like. Exemplary ROMs may include mask read-only memory (MROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disk read-only memory (CD-ROM), digital versatile disk read-only memory, etc. In some embodiments, storage device 150 may be implemented on a cloud platform, as described elsewhere in this application.

[0086] In some embodiments, the storage device 150 can be connected to the network 120 to communicate with one or more other components of the medical system 100 (e.g., the processing device 140, the terminal 130). One or more components of the medical system 100 can access data or instructions stored in the storage device 150 through the network 120. In some embodiments, the storage device 150 can be part of the processing device 140.

[0087] In some embodiments, the Figure 1 The medical system 100 shown uses a three-dimensional coordinate system 160. The first axis can be parallel to the lateral direction of the table (e.g., Figure 1 The second axis may be parallel to the longitudinal direction of the table (e.g., as shown in the X direction). Figure 1 The third axis may be parallel to the vertical direction of the table (e.g., Figure 1The origin of the three-dimensional coordinate system 160 may be any point in space. In some embodiments, the origin of the three-dimensional coordinate system 160 may be determined by an operator. In some embodiments, the origin of the three-dimensional coordinate system 160 may be determined by the medical system 100. In some embodiments, the position of one or more parts of an object (e.g., a target body) may be described using the three-dimensional coordinate system 160. In some embodiments, the three-dimensional coordinate system 160 may be used to describe the position of different parts of the treatment head 113.

[0088] This description is intended to illustrate, not to limit the scope of this specification. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other features of the exemplary embodiments described herein may be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the storage device 150 may be a data storage device for a cloud computing platform including a public cloud, a private cloud, a community, a hybrid cloud, etc. However, these changes and modifications do not depart from the scope of this disclosure.

[0089] Figure 2 is an exemplary schematic diagram of exemplary hardware and / or software components of a computing device according to some embodiments of the present disclosure. According to some embodiments of the present disclosure, processing device 140 may be implemented thereon. Figure 2 As shown, computing device 200 may include processor 210 , memory 220 , input / output (I / O) 230 , and communication port 240 .

[0090] The processor 210 can execute computer instructions (e.g., program code) according to the techniques of this article and perform the functions of the processing device 140. For example, the computer instructions may include routines, programs, objects, components, data structures, processes, modules, and functions of specific functions. For example, the processor 210 can process image data obtained from the medical device 110, the terminal 130, the storage device 150, and / or any other component of the medical system 100. In some embodiments, the processor 210 may include one or more hardware processors, such as a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application-specific integrated circuit (ASIC), an application-specific instruction set processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physical processing unit (PPU), a microcontroller unit, a digital signal processor (DSP), a field programmable gate array (FPGA), an advanced RISC machine (ARM), a programmable logic device (PLD), and any circuits and processors capable of performing one or more functions, etc., or any combination thereof.

[0091] For illustration purposes only, only one processor is described in the computing device 200. However, it should be noted that the computing device 200 in the present disclosure may also include multiple processors, and thus the steps and / or method steps described in the present disclosure as being performed by one processor may also be performed jointly or individually by multiple processors. For example, if in the present disclosure, the processor of the computing device 200 performs step A and step B simultaneously, then it should be understood that step A and step B may also be performed jointly or separately in the computing device 200 by two or more different processors (e.g., the first processor performs step A and the second processor performs step B, or the first and second processors jointly perform steps A and B).

[0092] The memory 220 may store data / information obtained from the medical device 110, the terminal 130, the storage device 150, and / or any other component of the medical system 100. In some embodiments, the memory 220 may include a mass storage device, a removable storage device, a volatile read-write memory, a read-only memory (ROM), etc., or any combination thereof. In some embodiments, the memory 220 may store one or more programs and / or instructions to perform the exemplary methods described in the present disclosure. For example, the memory 220 may store a program for the processing device 140 for modeling a radiation source configured to emit energy spectrum radiation containing different energies and / or determining a dose distribution in an object subjected to energy spectrum radiation from a radiation source.

[0093] I / O 230 can input and / or output signals, data, information, etc. In some embodiments, I / O 230 can enable a user to interact with processing device 140. In some embodiments, I / O 230 can include input devices and output devices. Exemplary input devices can include a keyboard, a mouse, a touch screen, a microphone, or any combination thereof. Exemplary output devices can include a display device, a speaker, a printer, a projector, or the like, or any combination thereof. Exemplary display devices can include a liquid crystal display (LCD), a display based on a light emitting diode (LED), a flat panel display, a curved screen, a television device, a cathode ray tube (CRT), a touch screen, etc., or any combination thereof.

[0094] The communication port 240 can be connected to a network (e.g., network 120) to facilitate data communication. The communication port 240 can establish a connection between the processing device 140 and the medical device 110, the terminal 130 and / or the storage device 150. The connection can be a wired connection, a wireless connection, any other communication connection that can realize data transmission and / or reception, and / or any combination of these connections. The wired connection may include a cable, an optical cable, a telephone line, etc., or any combination thereof. The wireless connection may include a Bluetooth connection, a Wi-Fi connection, a WiMax connection, a WLAN connection, a ZigBee connection, a mobile network connection (e.g., 3G, 4G, 5G), etc., or any combination thereof. In some embodiments, the communication port 240 may be a standardized communication port, such as RS232, RS485, etc. In some embodiments, the communication port 240 may be a specially designed communication port. For example, the communication port 240 may be designed according to the Digital Imaging and Communications in Medicine (DICOM) protocol.

[0095] Figure 3 300 is an exemplary schematic diagram of exemplary hardware and / or software components of a mobile device according to some embodiments of the present disclosure. In some embodiments, one or more components of the medical system 100 (eg, the terminal 130 and / or the processing device 140 ) can be implemented on the mobile device 300 .

[0096] like Figure 3 As shown, mobile device 300 may include communication platform 310, display 320, graphics processing unit (GPU) 330, central processing unit (CPU) 340, I / O device 350, memory 360 and storage 390. In some embodiments, any other suitable components, including but not limited to a system bus or controller (not shown) may also be included in mobile device 300. In some embodiments, a mobile operating system (OS) 370 (e.g., iOS) may be provided. TM 、Android TM 、Windows Phone TM The information stream may include a plurality of information processors, such as a processor 320, a processor 330, a processor 340, a processor 350, a processor 360, and a processor 370. The information stream may include a plurality of information processors, such as a processor 330, a processor 370, a processor 380, a processor 39 ...

[0097] In order to realize the various modules, units and functions thereof disclosed herein, a computer hardware platform can be used as the hardware platform of one or more elements of this article. A computer with a user interface element can be used to realize a personal computer (PC) or any other type of workstation or terminal device. If properly programmed, the computer can also serve as a server.

[0098] Figure 4 is a schematic diagram of an exemplary radiation source of the treatment head 113 according to some embodiments of the present disclosure. The radiation source of the treatment head 113 may be an electron linear accelerator configured to generate electron radiation and emit the electron radiation to the treatment object. Figure 4 As shown, the radiation source may include a generator 402, a scattering foil 404, a collimating assembly (or beam limiting assembly) 406, a plurality of electronic beam limiting cylinders 408, etc., or any combination thereof. When one of the plurality of electronic beam limiting cylinders 408 is installed, the radiation source is operable for radiation therapy.

[0099] Generator 402 may be configured to generate an accelerated electron beam (also referred to as a radiation beam) for radiation therapy of an object. For example, generator 402 may heat a tungsten filament in generator 402 to generate electrons. Generator 402 may generate a radiation beam by further accelerating the generated electrons. The radiation beam may be emitted from generator 402 through an exit window located at the bottom of generator 402.

[0100] In some embodiments, the radiation beam generated by the generator 402 can be a narrow beam with a relatively small scattering angle, for example, considered to correspond to a single energy. The scattering foil 404 can be configured to broaden the radiation beam according to the scattering properties of the electrons. In this case, the influence of the interaction between the generator 402 and the scattering foil 404 can be explained using the primary source. It should be noted that the primary source can be a hypothetical source according to the structure and layout of various components including the generator 402, the scattering foil 404, the scattering properties of the electrons, etc. In some embodiments, for simplicity, the generator 402 or the scattering foil 404 can be designated as the primary source.

[0101] The collimation assembly 406 may be configured to form a radiation beam. For example, the widened radiation beam may pass through the collimation assembly 406 to form a radiation beam having a specific shape (e.g., a cone beam). In some embodiments, the collimation assembly 406 may include a primary collimator, a secondary scattering foil, a secondary collimator, a multi-leaf collimator (MLC), etc. or any combination thereof. In some embodiments, the size of the radiation field of the collimation assembly 406 may be automatically adjusted according to the electronic light limiting cylinder 408 operably coupled to the primary source. That is, a specific electronic light limiting cylinder 408 may correspond to a specific size of the radiation field of the collimation assembly 406. As used herein, the radiation field of the collimation assembly 406 refers to the end opening of the collimation assembly 406 (e.g., the opening at the bottom end), through which the radiation beam can be emitted from the collimation assembly 406.

[0102] Each of the multiple electronic light-limiting tubes 408 can be configured to reduce electron leakage of the radiation beam and reshape the radiation beam. For example, a light beam with a specific shape emitted from the collimation assembly 406 can pass through the electronic light-limiting tube 408 to form radiation with a specific shape (e.g., square, circular) or referred to as a radiation beam. As used herein, the shape of the radiation or radiation beam refers to the shape of the cross-section of the radiation beam (constituting the radiation). In some embodiments, the specific shape of the radiation can be consistent with the shape (e.g., circular or square) of the end opening (e.g., bottom opening) of the electronic light-limiting tube 408, through which the radiation beam can be emitted from the electronic light-limiting tube 408. In some embodiments, multiple electronic light-limiting tubes 408 can facilitate the formation of different radiation beams. For example, the size of the end opening of the electronic light-limiting tube can be 6×6 cm 2 , 10×10cm 2 , 15×15cm 2 , 20×20cm 2 , 25×25cm 2 For simplicity, an electronic light-limiting tube with a specific end opening size can be referred to as an electronic light-limiting tube with a specific size. For example, an electronic light-limiting tube with a specific end opening size of 10×10 cm 2 The electronic light-limiting tube can be called 10×10cm 2 In some embodiments, each of the plurality of electronic light limiting tubes 408 may include a multi-layer structure (eg, a two-layer structure, a three-layer structure, or a four-layer structure). As an example only, the electronic light limiting tube 408 may include: Figure 4 Shown are a first portion (also referred to as an upper portion) 408-1, a second portion (also referred to as a middle portion) 408-2, and a third portion (also referred to as a lower portion) 408-3.

[0103] In some embodiments, the radiation beam generated by the primary source may include primary electrons and primary photons. The primary electrons may include a first portion and a second portion, wherein the first portion is not scattered within the radiation source. The second portion of the primary electrons may impact other components of the radiation source (e.g., collimation assembly 406, electronic light limiting cylinder 408, etc.) to produce secondary electrons. The primary photons may include a third portion and a fourth portion, wherein the third portion does not interact with other portions of the radiation source within the radiation source. The fourth portion of the primary photons may interact with other components of the radiation source (e.g., collimation assembly 406, electronic light limiting cylinder 408, etc.) to produce secondary photons.

[0104] The primary electrons and the secondary electrons may have different energies. For example, the primary electrons may have a relatively high energy, while the secondary electrons may have a relatively low energy. Thus, the radiation leaving the radiation source may correspond to an energy spectrum containing different energies (e.g., multiple electron energies). In some embodiments, the secondary electrons generated by the second portion of the primary electrons that impinge on the collimation assembly 406 may account for a relatively low percentage of the radiation passing through the object and may be ignored. In some embodiments, the secondary photons account for a relatively low percentage of the photon contamination and may be ignored.

[0105] In some embodiments, Figure 4 As shown, the radiation source can have an axis 412 that is perpendicular to the radiation source outlet. For example, the axis 412 can pass through the center of the electronic light limiting cylinder 408. As another example, the axis 412 can be parallel to the Z axis of the coordinate system 160.

[0106] In some embodiments, after leaving treatment head 113, the radiation can pass through the subject for radiation therapy. The radiation passing through the subject can include a first portion of primary electrons, secondary electrons, a third portion of primary photons, and secondary photons. During radiation therapy, the primary photons and the third portion of secondary photons can be considered photon contamination.

[0107] It should be noted that the above description is for illustration only and is not intended to limit the scope of the present disclosure. A person skilled in the art may make various changes or modifications under the guidance of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, the radiation source may further include a block 410 (e.g., such as Figure 4As shown, attached to the lower portion 408-3 of the electronic light limiting cylinder 408). Block 410 can be configured to further form the radiation beam. Block 410 may include an opening for modulating the radiation beam to a size that is smaller than the radiation beam leaving the electronic light limiting cylinder 408. The opening of block 410 can be a regular shape (e.g., a triangle, a hexagon, an ellipse, a rectangle, etc.) or an irregular shape. The block can be made of a radiation-impenetrable material, such as lead. In this case, the radiation leaving the radiation source (and subsequently passing through the object) can include secondary electrons generated by a second portion of the primary electrons that impinge on block 410.

[0108] Figure 5A and Figure 5B A block diagram of an exemplary processing device according to some embodiments of the present disclosure is shown. In some embodiments, processing devices 140A and 140B may be combined Figure 1 In some embodiments, the processing devices 140A and 140B may be implemented on processing units (eg, Figure 2 The processor 210 shown or Figure 3 As an example only, processing device 140A may be implemented on CPU 340 of the terminal device, and processing device 140B or processing device 140A may be implemented on computing device 200. Alternatively, processing devices 140A and 140B may be implemented on the same computing device 200 or the same CPU 340. For example, processing devices 140A and 140B may be implemented on the same computing device 200.

[0109] like Figure 5A As shown, the processing device 140A may include an acquisition module 510 , a calculation module 502 , and a determination module 503 .

[0110] The acquisition module 501 may be configured to acquire information / data from one or more components of the medical system 100. For example, the acquisition module 501 may acquire an initial multi-source model of a radiation source having a specific energy setting. The radiation source may correspond to an energy spectrum containing multiple energies. The initial multi-source model may include an initial phase space file. The multi-source model may include a primary virtual source and a secondary virtual source. As another example, the acquisition module 501 may acquire measurement data related to energy spectrum radiation. For example, the measurement data may include a measured PDD curve and / or a measured OAR curve corresponding to the energy spectrum radiation passing through the phantom in the phantom, an output factor corresponding to each of a plurality of electronic light limiting cylinders, and the like. More descriptions of obtaining the initial multi-source model and measurement data may be found elsewhere in the present disclosure (e.g., steps 610, 820, 1010, 1110 and descriptions thereof).

[0111] The calculation module 502 can be configured to determine calculation data related to energy spectrum radiation. For example, the calculation module 502 can calculate multiple PDD curves corresponding to multiple energies of the energy spectrum in the phantom based on the initial phase space file. As another example, the calculation module 502 can determine the simulated OAR curve in the phantom based on the initial parameters of the primary virtual source and the initial phase space file. As another example, the calculation module 502 can determine the simulated output factor corresponding to each of the multiple electronic light-limiting cylinders based on the structural parameters and energy spectrum of the electronic mouth cone. More descriptions about the determination of calculation data can be found elsewhere in the present disclosure (e.g., steps 810, 1020, 1120 and their descriptions).

[0112] The determination module 503 may be configured to determine a target multi-source model. For example, the determination module 503 may determine the weight of each of the different energies. As another example, the determination module 503 may determine the weight of the photon. In addition, the determination module 503 may determine the energy spectrum based on the weights of the different energies and the weights of the photons. As a further example, the determination module 503 may determine the parameters of the main virtual source of the initial multi-source model. As another example, the determination module 503 may determine the correction coefficient of the electron mouth inner cone of the main source operably coupled to the radiation source. In addition, the determination module 503 may determine the target multi-source model of the radiation source corresponding to the energy spectrum based at least in part on the initial multi-source model, the weights, the parameters of the main virtual source, and the correction coefficients. More descriptions of the determination of weights, the parameters of the main virtual source, the correction coefficients, and / or the target multi-source model may be found elsewhere in the present disclosure (e.g., steps 620-650, 830-840, 1030-1060, 1130 and descriptions thereof).

[0113] like Figure 5B As shown, the processing device 140B may include an acquisition module 504 and a determination module 505 .

[0114] The acquisition module 504 can be configured to acquire information / data related to the process of determining the dose distribution of the object. For example, the acquisition module 501 can acquire a target multi-source model of a radiation source with a specific energy setting. The acquisition module 504 can acquire structural parameters of an electronic light-limiting cylinder of the radiation source. For another example, the acquisition module 504 can acquire a transmission model from any storage device.

[0115] The determination module 505 may be configured to determine the dose distribution in the object. For example, the determination module 505 may input the structural parameters of the electronic light-limiting cylinder into the target multi-source model and then determine the phase space file. The phase space file may include information of a plurality of simulated particles corresponding to the radiation of the radiation source. The determination module 505 may determine the dose distribution in the object based on the phase space file and the transmission model.

[0116] It should be noted that the above description is for illustration only and is not intended to limit the scope of the present disclosure. Obviously, for those of ordinary skill in the art, various changes and modifications can be made under the guidance of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. Each of the above modules can be a hardware circuit, which is designed to, for example, perform certain operations according to a set of instructions stored in one or more storage media and / or any combination of a hardware circuit and one or more storage media.

[0117] In some embodiments, processing device 140A and processing device 140B may share two or more modules, and any one of the modules may be divided into two or more units. For example, processing device 140A and processing device 140B may share the same acquisition module (i.e., acquisition module 501 and acquisition module 504 may be the same acquisition module). In some embodiments, processing device 140A and processing device 140B may include one or more additional modules, such as a storage module (not shown) for storing data. In some embodiments, processing device 140A and processing device 140B may be integrated into one processing device 140.

[0118] Figure 6 is a flow chart of an exemplary process for modeling a radiation source according to some embodiments of the present disclosure. In some embodiments, process 600 may be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140A, processor 210, and / or CPU 340 may execute the instructions, and when executing the instructions, processing device 140A, processor 210, and / or CPU 340 may be configured to perform process 600. The steps of the process shown below are for illustration only. In some embodiments, process 600 may be completed with one or more additional steps not described and / or without one or more of the steps discussed. In addition, Figure 6 The order of the steps of process 600 shown and described below is not limiting. For illustrative purposes, process 600 may be combined with Figure 4 The radiation sources shown are described and are not intended to be limiting.

[0119] In some cases, due to factors such as production accuracy, assembly process, temperature, humidity, etc., even the dose distribution of multiple radiation sources of the same type (such as linear accelerators) produced by the same manufacturer may be inconsistent to a certain extent. The radiation source may need special modeling. The radiation source can generate electron beams (for example, 8MeV, 10MeV or 12MeV) at different optional energy settings. Traditionally, modeling of radiation sources for specific energy settings requires consideration of different electronic light limiting cylinders of the radiation source. That is, in the process of modeling the radiation source, for each of the different electronic light limiting cylinders, the radiation energy spectrum of the radiation source under a specific energy setting can be determined separately, which is complicated and time-consuming. In some embodiments, process 600 can be performed to effectively model the radiation source for a specific optional energy setting. For illustrative purposes, the modeling process for a radiation source that does not include a block is described.

[0120] In step 610 , the processing device 140A (eg, the acquisition module 501 ) may acquire an initial multi-source model corresponding to a radiation source having an energy spectrum including multiple energies.

[0121] Ideally, a radiation source may emit radiation of a specific energy (e.g., an electron beam). Accordingly, the energy spectrum of the radiation emitted by the radiation source may also be considered to correspond to the specific energy. In practice, the radiation of the radiation source may include different components (e.g., electrons and / or photons) with different energies, and the total energy (or average energy) of the different components may be substantially equal to the specific energy.

[0122] like Figure 4 The radiation source may include at least one main source and a plurality of electronic light-limiting cylinders. One of the plurality of electronic light-limiting cylinders may be designated as a reference electronic light-limiting cylinder for simulating the radiation source. For example, the radiation source may include five 6×6 cm 2 , 10×10cm 2 , 15×15cm 2 , 20×20cm 2 and 25×25cm 2 Electronic light-limiting tube. For example, 10×10cm 2 The electronic light-limiting cylinder of can be designated as the reference electronic light-limiting cylinder. In this case, the radiation source can be modeled based on the reference electronic light-limiting cylinder. The initial multi-source model can be associated with the reference electronic light-limiting cylinder. That is, the 10×10 cm 2 The electronic light limiting cylinder sets the parameters of the initial multi-source model. In some embodiments, for the sake of brevity, the reference electronic light limiting cylinder may also be referred to as the electronic light limiting cylinder.

[0123] In some embodiments, the initial multi-source model may include an initial phase space file including information of a plurality of simulated particles. The plurality of simulated particles may be used to simulate different compositions of radiation from a radiation source. As used herein, radiation from a radiation source refers to electrons and / or photons emitted from an electron confining tube (e.g., an opening at the end) of the radiation source. Figure 4 The multiple simulated particles may include: a first part corresponding to primary electrons generated by the main source that are not scattered within the radiation source, a second part corresponding to primary photons generated by the main source that do not interact with other components of the radiation source, a third part corresponding to secondary electrons generated by primary electrons generated by the main source hitting the reference electron light-limiting cylinder, and so on. In some embodiments, the initial multi-source model may include multiple virtual sources corresponding to the multiple simulated particles. For example, the initial multi-source model may include a main virtual source and a secondary virtual source. The main virtual source may correspond to a first part of simulated particles and a second part of simulated particles, which are used to simulate the main source. The secondary virtual source may correspond to a third part of simulated particles used to simulate the reference electron light-limiting cylinder. In some embodiments, the main virtual source may be a point source (also called a first point source) (for example, Figure 7 The primary virtual source 702 shown in FIG. 1 ). The primary virtual source may have an axis that coincides with the axis of the radiation source. The secondary virtual source may include a second point source (e.g., Figure 7 The second point source 704 shown) and the area source (e.g., Figure 7 In some embodiments, for simplicity, the axis of the main virtual source may be referred to as the axis of the radiation source. More description of multiple virtual sources may be found elsewhere in this disclosure (e.g., Figure 7 and its related description).

[0124] In some embodiments, the initial phase space may include initial parameters of multiple virtual sources of the initial multi-source model. The initial parameters of the multiple virtual sources may be determined based on the structural parameters of the radiation source. For example, the initial parameters of the main virtual source may be determined based on one or more components of the radiation source (e.g., the target and / or scattering foil of the radiation source). As another example, the initial parameters of the second point source and / or the surface source of the secondary virtual source may be determined based on the structural parameters of the reference electronic light-limiting cylinder. More description of the initial parameters of multiple virtual sources may be found elsewhere in the present disclosure (e.g., Figure 7 and its description).

[0125] In some embodiments, the processing device 140A can determine the initial phase space file of the initial multi-source model based on direct sampling. For example, the initial phase space file may include the position of the first part of the simulated particles and the direction of the first part of the simulated particles. As used in this specification, the position of a simulated particle in the first part of the simulated particles refers to the position of the simulated particle on a first plane perpendicular to the axis of the main virtual source (e.g., a plane parallel to the XY plane of the coordinate system 160 where the main virtual source 702 is located). The first plane can be centered on the place where the axis of the main virtual source intersects with the first plane. The direction of a simulated particle in the first part of the simulated particles refers to the exit angle of the simulated particle relative to the axis of the main virtual source when it is ejected from the main virtual source. The area of ​​the first plane may be related to the size of the main virtual source. Since the first part of the simulated particles can correspond to the first part of the primary electrons generated by the main source and not scattered in the radiation source, and most of the first part of the primary electrons can be (substantially) emitted from the main source along the axis of the radiation source, the particle flux distribution of the first part of the simulated particles as a function of the distance from the center of the first plane (for example, the intersection of the axis of the main virtual source and the first plane) or the distance from the center of the plane parallel to the first plane can be assumed to conform to a first distribution function (for example, a first Gaussian function). That is to say, the probability that any one of the first part of the simulated particles leaves the main virtual source from a position close to the center of the first plane can be greater than the probability that the simulated particles leave the main virtual source from a position far from the center of the first plane; if the first angle is smaller than the second angle, the probability that any one of the first part of the simulated particles leaves the main virtual source in a direction at a first angle to the axis of the main virtual source is greater than the probability that the first part of the simulated particles leaves the main virtual source in a direction at a second angle to the axis of the main virtual source; the probability that any one of the first part of the simulated particles passes through a plane parallel to the first plane at a position near the center of the plane parallel to the first plane can be greater than the probability that the simulated particles pass through a plane parallel to the first plane at a position farther away from the center of the plane parallel to the first plane.

[0126] In this case, the processing device 140A can determine the position of the first part of the simulated particles or the direction of the first part of the simulated particles by first direct sampling based on the first distribution function. For example, for the first part of the simulated particles, the number (or count) of simulated particles leaving the main virtual source from a certain position on the first plane depends on the distance between the position and the center of the first plane; the smaller the distance between the position and the center of the first plane, the more the number (or count) of simulated particles leaving the main virtual source from the position. As another example, for the first part of the simulated particles, the number (or count) of simulated particles leaving the main virtual source in a direction at a certain angle to the axis of the main virtual source depends on the angle; the smaller the angle between the direction and the axis of the main virtual source (that is, the more aligned the direction is with the axis of the main virtual source), the more the number (or count) of simulated particles leaving the main virtual source along the direction. As a further example, for the first part of the simulated particles, the number (or count) of simulated particles passing through the first plane from a certain position on the first plane depends on the particle flux at the position on the first plane. The particle flux at a position on the first plane refers to the number (or count) of simulated particles crossing the first plane at the position on the first plane per unit area of ​​the first plane (the center of which is the position). The closer a position on the first plane is to the center of the first plane, the higher the particle flux of the simulated particles at the position. As another example, for each of the first part of the simulated particles, the processing device 140A may determine the position of the simulated particle on the first plane, at which the simulated particle may leave the main virtual source through the first sub-sampling of the first sampling. The processing device 140A may determine the position of the simulated particle on a plane parallel to the first plane, wherein the simulated particle may pass through the plane parallel to the first plane through the second sub-sampling of the first direct sampling. The processing device 140A may further determine the direction of the simulated particle based on the position of the simulated particle on the first plane and the position of the simulated particle on the plane parallel to the first plane.

[0127] As another example, the initial phase space file may include the position of the third part of the simulated particle and the direction of the third part of the simulated particle. In some embodiments, the third part of the simulated particle may include a first sub-part of the simulated particle corresponding to the second point source (e.g., the second point source 704) and a second sub-part of the simulated particle corresponding to the surface source (e.g., the surface source 706). The position of the third part of the simulated particle may include the position of the first sub-part of the simulated particle and the position of the second sub-part of the simulated particle. The direction of the third part of the simulated particle may include the direction of the first sub-part of the simulated particle and the direction of the second sub-part of the simulated particle. Similar to the first part of the simulated particle, the position of one of the first sub-parts of the simulated particle refers to the position of the simulated particle on the second plane perpendicular to the axis of the secondary virtual source (e.g., the plane parallel to the XY plane of the coordinate system 160 where the second point source 704 is located). The second plane may be centered at the position where the axis of the secondary virtual source intersects with the second plane. The area of ​​the second plane may be related to the size of the second point source. The direction of one of the first sub-parts of the simulated particle refers to the exit angle of the simulated particle relative to the axis of the primary virtual source when the simulated particle is emitted from the second point source of the secondary virtual source. The position of the first one in the second sub-portion of the simulated particle refers to the position of the simulated particle on a third plane perpendicular to the axis of the secondary virtual source (e.g., a plane parallel to the XY plane of the coordinate system 160 where the surface source 706 is located). The third plane can be centered on the position where the axis of the secondary virtual source intersects the third plane. The third plane can have the same size and shape as the end opening of the reference electronic light-limiting tube. The direction of each of the second sub-portions of the simulated particle refers to the exit angle of the simulated particle relative to the axis of the main virtual source when it is emitted from the surface source of the secondary virtual source. As a further example, for each of the first sub-portions of the simulated particle, the processing device 140A can determine the position of the simulated particle on the second plane by the first sub-sampling of the second sampling, at which position the simulated particle can leave the second point source by the first sub-sampling of the second sampling. The processing device 140A can determine the position of the simulated particle on the plane parallel to the second plane, at which position the simulated particle can pass through the plane parallel to the second plane by the second sub-sampling of the second direct sampling. Processing device 140A may further determine the direction of the simulated particle based on the position of the simulated particle on the second plane and the position of the simulated particle on a plane parallel to the second plane.

[0128] In some embodiments, since it can be assumed that the first sub-portion of the simulated particles is generated by a second point source of the secondary virtual source, and most of the first sub-portion of the simulated particles can (substantially) move away from the second point source along the axis of the secondary virtual source, the particle flux distribution of the first sub-portion of the simulated particles as a function of the distance from the center of the second plane (e.g., the intersection of the axis of the main virtual source and the second surface) or the distance from the center of the plane parallel to the second plane can be assumed to conform to a second distribution function (e.g., a second Gaussian function). That is, the probability that any one of the first sub-portions of the simulated particles leaves the second point source from a position close to the center of the second plane (for example, the intersection point where the axis of the main virtual source intersects the second plane) may be greater than the probability that the simulated particle leaves the second point source from a position far from the center of the second plane; if the third angle is less than the fourth angle, the probability that any one of the first sub-portions of the simulated particles is emitted from the second point source in a direction at a third angle to the axis of the main virtual source may be greater than the probability that the simulated particle is emitted from the second point source in a direction at a fourth angle to the axis of the main virtual source; the probability that any one of the first sub-portions of the simulated particles passes through a plane parallel to the second plane at a position close to the center of the plane parallel to the second plane may be greater than the probability that the simulated particle passes through a plane parallel to the second plane at a position far from the center of the plane parallel to the second plane. In this case, the processing device 140A may determine the position of the first sub-portion of the simulated particle or the direction of the first sub-portion of the simulated particle by second direct sampling based on the second distribution function. For example, for the first sub-portion of simulated particles, the number (or count) of simulated particles leaving the second point source from a certain position on the second plane depends on the distance between the position and the center of the second plane; the smaller the distance between the position and the center of the second plane, the greater the number (or count) of simulated particles leaving the second point source from the position. As another example, for the first sub-portion of simulated particles, the number (or count) of simulated particles leaving the second point source in a direction at an angle to the axis of the main virtual source depends on the angle; the smaller the angle between the direction and the axis of the main virtual source (i.e., the more aligned the direction is with the axis of the main virtual source), the greater the number (or count) of simulated particles leaving the main virtual source along the direction. As another example, for the first sub-portion of simulated particles, the number (or count) of simulated particles leaving the second point source from a certain position on the second plane depends on the particle flux at the position on the second plane. The particle flux at a certain position on the second plane refers to the number (or count) of simulated particles passing through the second plane at the position on the second plane per unit area of ​​the second plane (whose center is the position). The closer a position on the second plane is to the center of the second plane, the higher the particle flux of the simulated particles at the position.

[0129] In some embodiments, since it can be assumed that the second sub-portion of the simulated particles is generated by the surface source of the secondary virtual source, the particle flux distribution of the second sub-portion of the simulated particles as a function of the distance from the center of the third plane or the distance from the center of the plane parallel to the third plane can be assumed to conform to a third distribution function (e.g., a uniform function). That is, the probability that any one of the second sub-portions of the simulated particles leaves the surface source from the first position on the third plane can be equal to the probability that the simulated particle leaves the surface source from the second position on the third plane; the probability that any one of the second sub-portions of the simulated particles is emitted from the surface source in a direction at a fifth angle to the axis of the main virtual source can be equal to the probability that the simulated particle is emitted from the surface source in a direction at a sixth angle to the axis of the main virtual source; the probability that any one of the second sub-portions of the simulated particles passes through a plane parallel to the third plane at a position close to the center of the plane parallel to the third plane can be equal to the probability that the simulated particle passes through a plane parallel to the third plane at a position far from the center of the plane parallel to the third plane. In such a case, the processing device 140A can determine the position of the second sub-portion of the simulated particle or the direction of the second sub-portion of the simulated particle by a third direct sampling based on the third distribution function. For example, for the second sub-portion of simulated particles, the number (or count) of simulated particles emitted from the surface source at any position of the third plane may be the same. As another example, for the second sub-portion of simulated particles, the number (or count) of simulated particles emitted from the surface source at any angle to the axis of the main virtual source may be the same. As a further example, for each of the second sub-portion of simulated particles, the processing device 140A may determine the position of the simulated particle on the third plane by the first sub-sampling of the third sampling, at which the simulated particle can leave the second point source by the first sub-sampling of the third sampling. The processing device 140A may determine the position of the simulated particle on the plane parallel to the third plane, wherein the simulated particle may pass through the plane parallel to the third plane by the second sub-sampling of the third direct sampling. The processing device 140A may further determine the direction of the simulated particle based on the position of the simulated particle on the third plane and the position of the simulated particle on the plane parallel to the third plane.

[0130] In some embodiments, before determining the positions and directions of the plurality of simulated particles, the processing device 140A may determine the number (or count) of the plurality of simulated particles. The number of simulated particles may be determined based on the radiation field of the radiation source. The radiation field of the radiation source may be related to the end opening of the reference electronic light limiting cylinder. For example, the number of simulated particles may be determined according to formula (1):

[0131] N = γ*R / μ^ 2 / S^ 2 , (1)

[0132] Where N represents the number of simulated particles, γ represents a constant (e.g., 10^3), R represents the area of ​​the radiation field of the radiation source, μ represents the uncertainty value, and S represents the grid size (e.g., 4 mm, 8 mm, 16 mm, etc.). R, μ, or S may be a default setting determined by a user of the medical system. For a 10×10 cm 2 The radiation field area of ​​the radiation source can be 10×10cm 2 .

[0133] In step 620, the processing device 140A (eg, the acquisition module 501, the calculation module 502, and the determination module 503) may determine a weight for each energy based on the calculated PDD curves corresponding to different energies in the phantom and the measured PDD curves in the phantom corresponding to the energy spectrum radiation passing through the phantom.

[0134] In some embodiments, the processing device 140A may calculate different energy percentage depth dose (PDD) curves in a phantom (e.g., a water phantom) based on an initial phase space file. Each of the different energy PDD curves may correspond to an energy. The processing device 140A may obtain a measured PDD curve in the phantom corresponding to the radiation whose energy spectrum passes through the phantom. For each of the different energies, the processing device 140A may determine the weight of each energy based on the different energy PDD curves and the measured PDD curve. The weight of each energy may represent the percentage of simulated particles of each energy among multiple simulated particles present in the radiation. As used herein, since multiple simulated particles are used to simulate different compositions of radiation, for simplicity, multiple simulated particles may be referred to as being present in the radiation. In some embodiments, each energy PDD curve and the measured PDD curve may correspond to the same electronic light limiting tube (e.g., 10×10 cm 2 The reference electronic light-limiting cylinder of FIG. 100 ) and the same source-skin distance (SSD) (e.g., 100 cm). In this document, SSD refers to the distance between the main source and the phantom surface (e.g., the upper surface of the water phantom) where the radiation first hits the phantom. More description of the determination of the weight of each energy can be found elsewhere in this disclosure (e.g., Figure 8 and its related description).

[0135] In some embodiments, processing device 140A may calculate the average energy of the photons (e.g., the third portion of the primary photons) based on the energy. For example, processing device 140A may designate a particular energy corresponding to the energy spectrum as the calculated average energy of the photons. Processing device 140A may determine the measured average energy of the photons based on the measured PDD curve. For example, Fig. 9 As shown, a portion of the measured PDD curve 901 (in the dashed box 903) may represent photon contamination. The processing device 140A may specify an energy corresponding to the photon contamination (e.g., Fig. 9 The energy represented by the midpoint 905) is used as the measured average energy. The processing device 140A may determine the weight of the photon based on the calculated average energy and the measured average energy. The weight of the photon may be equal to the ratio between the measured average energy and the calculated average energy. In some embodiments, the processing device 140A may further determine the energy spectrum based on the weights of different energies and the weight of the photon. The energy spectrum may indicate the distribution of different energies in the radiation. The greater the weight of the energy, the higher the proportion or percentage of the energy in the energy spectrum may be. The radiation energy spectrum of the radiation source determined with reference to the reference electronic confining tube at a specific energy setting can be used to determine the target multi-source model of the radiation source for different electronic confining tubes at the specific energy setting. According to some embodiments of the present disclosure, it is not necessary to analyze the energy spectrum of the radiation source at a specific energy setting for different electronic confining tubes.

[0136] In step 630, the processing device 140A (e.g., the acquisition module 501, the calculation module 502, and the determination module 503) may determine the parameters of the main virtual source of the initial multi-source model based on the simulated OAR (off-axis ratio) curve and the measured OAR curve corresponding to the energy spectrum radiation passing through the phantom.

[0137] In some embodiments, the processing device 140A may obtain a measured OAR curve corresponding to the energy spectrum radiation passing through the phantom. The processing device 140A may calculate (or simulate) a simulated OAR curve based on the initial parameters of the main virtual source and the initial phase space file. The processing device 140A may adjust the initial parameters of the main virtual source based on the simulated OAR curve and the measured OAR curve, thereby determining the parameters of the main virtual source. In some embodiments, the simulated OAR curve and the measured OAR curve may correspond to the same electronic light limiting tube (e.g., 10×10 cm 2 More description on the determination of the parameters of the master virtual source can be found elsewhere in this disclosure (e.g., Fig.10 and its description).

[0138] In step 640, the processing device 140A (eg, the acquisition module 501, the calculation module 502, and the determination module 503) may determine a correction coefficient of an electronic confining cylinder coupled to the primary source. The electronic confining cylinder may be one of a plurality of electronic confining cylinders other than a reference electronic confining cylinder.

[0139] In some embodiments, the processing device 140A may obtain an output factor corresponding to the electronic light limiting cylinder based on a reference electronic light limiting cylinder. The output factor corresponding to the electronic light limiting cylinder may indicate a ratio between a maximum dose corresponding to the electronic light limiting cylinder and a maximum dose corresponding to the reference electronic light limiting cylinder. The output factor corresponding to the electronic light limiting cylinder may be greater than 1 or less than 1. The output factor of the reference electronic light limiting cylinder may be equal to 1. The processing device 140A may determine a simulated output factor corresponding to the electronic light limiting cylinder based on the structural parameters and energy spectrum of the electronic light limiting cylinder.

[0140] The processing device 140A may further determine the correction factor of the electronic light limiting cylinder based on the output factor corresponding to the electronic light limiting cylinder and the simulated output factor corresponding to the electronic light limiting cylinder. More descriptions on the determination of the correction factor of the electronic light limiting cylinder may be found elsewhere in this disclosure (e.g., Fig.11 and its description).

[0141] At step 650 , the processing device 140A (eg, the determination module 503 ) may determine a target multi-source model of radiation sources corresponding to the energy spectrum based at least in part on the initial multi-source model, weights, parameters of the master virtual source, and correction coefficients.

[0142] In some embodiments, the target multi-source model may include a target phase space file. The processing device 140A may determine the target space file by updating the initial phase space file of the initial multi-source model based at least in part on the weights, parameters, and correction coefficients of the main virtual source. For example, the target phase space file may further include an energy spectrum determined based on the weights. As another example, the initial parameters of the main virtual source in the initial phase space file may be updated by merging the parameters of the main virtual source. As a further example, the target phase space file may further include a plurality of correction coefficients corresponding to a plurality of electronic light limiting cylinders. When applying the target multi-source model, a specific correction coefficient may be selected from a plurality of correction coefficients according to a specific electronic light limiting cylinder.

[0143] In the traditional modeling process, it may be necessary to consider multiple virtual sources and adjust the parameters of each virtual source, which is relatively complicated; it may be necessary to determine multiple energy spectra for multiple electronic light-limiting cylinders respectively, which is time-consuming; the initial phase space file may contain a large amount of scattering nuclear data indicating the positions and directions of multiple simulated particles, which need to be pre-calculated and stored, occupying storage space and computing resources. According to some embodiments of the present disclosure, a target multi-source model corresponding to a radiation source of a specific energy may include fewer virtual sources than a traditional multi-source model. In the process of constructing the target multi-source model, the processing device 140A can determine the initial parameters of the virtual source based on the structural parameters of the radiation source; determine the initial phase space file based on direct sampling; only adjust the initial parameters of the main virtual source; and based on the reference electronic light-limiting cylinder of multiple electronic light-limiting cylinders, only determine an energy spectrum corresponding to the specific energy setting of the radiation source, so that the modeling process is more efficient and accurate.

[0144] It should be noted that the above description of process 600 is provided for the purpose of illustration only, and is not intended to limit the scope of the present disclosure. For those with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, one or more steps can be omitted and / or one or more additional steps can be added. For example, process 600 can further include a step for storing information and / data (e.g., a target multi-source model) generated during the modeling process. In addition or alternatively, process 600 can also include a step for determining the weight of a photon. In some embodiments, the initial multi-source model may include an additional virtual source. For example, the initial multi-source model may include a third virtual source of secondary electrons, the third virtual source corresponding to the second part of the primary electrons impacting the collimation component 406, for simulating the collimation component 406. The third virtual source can be a line source. A plurality of simulated particles may include a fourth part, the fourth part corresponding to the secondary electrons generated by the second part of the primary electrons impacting the collimation component 406. In some embodiments, the position and direction of the fourth part of the simulated particles can be determined based on direct sampling (e.g., based on a uniform distribution).

[0145] Figure 7 Schematic diagram of an exemplary virtual source of an initial multi-source model of a radiation source according to some embodiments of the present disclosure. Figure 7As shown, the initial multi-source model of the radiation source of the treatment head 113 may include a primary virtual source and a secondary virtual source. The primary virtual source may be a point source (also referred to as the primary virtual source 702). The primary virtual source 702 may include an axis that coincides with the axis 412 of the radiation source. The secondary virtual source may correspond to a reference electronic light-limiting cylinder (e.g., the electronic light-limiting cylinder 408) of the radiation source. The secondary virtual source may include a second point source 704 and a surface source 706. In some embodiments, the primary virtual source 702 or the second point source 704 may include any shape. For example, the primary virtual source 702 or the second point source 704 may be a circular point source, a square point source, etc. The following description is provided with reference to the primary virtual source 702 and the second point source 704 as circular point sources. It should be understood that this is for illustrative purposes and not for limitation.

[0146] The main virtual source 702 may include initial parameters, including, for example, the size of the main virtual source 702, the vertical position of the main virtual source 702 along the axis of the main virtual source 702 (also referred to as the height position of the main virtual source 702), the particle flux distribution of the main virtual source 702, etc., or any combination thereof. As an example only, the size of the circular main virtual source 702 refers to the diameter of the main virtual source 702 (e.g., 2 mm, 1.5 mm, etc.). The particle flux of the main virtual source 702 refers to the number (or count) of simulated particles per unit area of ​​the fourth plane perpendicular to the axis of the main virtual source 702. For simplicity, the fourth plane perpendicular to the axis of the main virtual source 702 may also be referred to as a horizontal plane. The horizontal plane may be centered at the position where the axis of the main virtual source 702 intersects with the horizontal plane. Accordingly, the particle flux distribution of the main virtual source 702 refers to the distribution of multiple particle fluxes of the main virtual source 702 on the horizontal plane, which is a function of the distance from the center of the horizontal plane. Similar to the particle flux distribution of the first part of the simulated particles on the first plane in step 610, the particle flux distribution of the main virtual source 702 can be assumed to conform to a fourth distribution function (e.g., a third Gaussian function). That is, the probability of the simulated particle passing through the horizontal plane at a position close to the center of the horizontal plane (e.g., the intersection point where the axis of the main virtual source 702 intersects the horizontal plane) can be greater than the probability of the simulated particle passing through the horizontal plane at a position far from the center of the horizontal plane. In some embodiments, the initial parameters of the main virtual source 702 can be determined based on the structural parameters of the generator 402 and the scattering foil 404. As an example only, the height position of the main virtual source 702 can be set between the height position of the generator 402 and the height position of the scattering foil 404. As another example, the height position of the main virtual source 702 can be set to coincide with the height position of the generator 402.

[0147] The second point source 704 may correspond to the upper portion 408-1 and the middle portion 408-2 of the electronic light limiting tube 408. The second point source 704 may include initial parameters, including the size of the second point source 704, the vertical position of the second point source 704 along the axis of the secondary virtual source (also referred to as the height position of the second point source 704), the particle flux distribution of the second point source 704, etc., or any combination thereof. As an example only, the size of the circular second point source 704 refers to the diameter of the second point source 704 (e.g., 2 mm, 1.5 mm, etc.). The particle flux of the second point source 704 refers to the number (or count) of simulated particles per unit area of ​​the fifth plane perpendicular to the axis of the secondary virtual source. For simplicity, the fifth plane perpendicular to the axis of the secondary virtual source may also be referred to as the second horizontal plane. The second horizontal plane may be centered at the position where the axis of the main virtual source intersects with the second horizontal plane. Correspondingly, the particle flux distribution of the second point source 704 refers to the distribution of multiple particle fluxes of the second point source 704 on the second horizontal plane, which is a function of the distance from the center of the second horizontal plane. Similar to the particle flux distribution of the first sub-portion of the simulated particle on the second plane in step 610, it can be assumed that the particle flux distribution of the second point source 704 conforms to the fifth distribution function (e.g., the fourth Gaussian function). That is, the probability of the simulated particle passing through the second horizontal plane at a position close to the center of the second horizontal plane (e.g., the intersection where the axis of the main virtual source intersects with the second horizontal plane) can be greater than the probability of the simulated particle passing through the second horizontal plane at a position away from the center of the second horizontal plane. In some embodiments, the initial parameters of the second point source 704 can be determined based on the structural parameters of the electronic light-limiting tube 408. As an example only, the height position of the second point source 704 can be specified as coinciding with a certain height position (e.g., center position) between the upper part 408-1 and the middle part 408-2.

[0148] The surface source 706 may correspond to the lower part 408-3 of the electronic light-limiting tube 408. The surface source 706 may include initial parameters, including the size of the surface source 706, the vertical position of the surface source 706 along the axis of the main virtual source (also referred to as the height position of the surface source 706), the particle flux distribution of the surface source 706, etc., or any combination thereof. As an example only, the size of the surface source 706 refers to the area and shape of the surface source 706. The particle flux of the surface source 706 refers to the number (or count) of simulated particles per unit area of ​​the sixth plane perpendicular to the axis of the main virtual source. For the sake of simplicity, the sixth plane perpendicular to the axis of the main virtual source may also be referred to as the third horizontal plane. Accordingly, the particle flux distribution of the surface source 706 refers to the distribution of multiple particle fluxes of the surface source 706 on the third horizontal plane, which is a function of the distance from the center of the third horizontal plane. Similar to the particle flux distribution of the second sub-portion of the simulated particles in step 610, it can be assumed that the particle flux distribution of the surface source 706 conforms to the sixth distribution function (e.g., the second uniform function). That is, the probability of simulating the particle passing through the third horizontal plane at the first position on the third horizontal plane can be equal to the probability of simulating the particle passing through the third horizontal plane at the second position on the third horizontal plane. In some embodiments, the initial parameters of the surface source 706 can be determined based on the structural parameters of the electronic light limiting cylinder 408. As an example only, the size of the surface source 706 can be the same as the size of the end opening of the electronic light limiting cylinder 408. As another example, the height position of the surface source 706 can be specified to coincide with the height position of the lower portion 408-3.

[0149] It should be noted that the above description is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. For those with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, the radiation source of the treatment head 113 may also include a block (e.g., Figure 4 The processing device 140 may further determine initial parameters of the surface source 706 based on the structural parameters of the block. For example, the size of the surface source 706 may be the same as the size of the opening of the block.

[0150] Figure 8is a flowchart of an exemplary process for determining a weight for each of the different energies of the energy spectrum of a radiation source according to some embodiments of the present disclosure. In some embodiments, process 800 may be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140A, processor 210, and / or CPU 340 may execute the instructions, and when executing the instructions, processing device 140A, processor 210, and / or CPU 340 may be configured to perform process 800. The steps of the process shown below are for illustration only. In some embodiments, process 800 may be completed by one or more additional steps not described and / or one or more steps that do not need to be discussed. In addition, Figure 8 The order of steps of process 800 shown and described below is not limiting. In some embodiments, the energy spectrum described elsewhere in the present disclosure (e.g., Figure 6 Step 620 shown).

[0151] In step 810, the processing device 140A (e.g., the computing module 502) may calculate different energy PDD curves in the phantom corresponding to different energies of the energy spectrum based on the initial phase space file of the initial multi-source model. The energy spectrum may correspond to the energy setting of the radiation source providing the average energy (e.g., 6MeV, 12MeV, 18MeV, etc.). Each PDD curve may correspond to an energy. For example, when the average energy of the energy spectrum is 12MeV, the multiple energies may include energies of 1MeV, 2MeV, ..., 12MeV, 13MeV, ..., respectively. The average energy of the different energies may be 12MeV.

[0152] The initial phase space file may correspond to a certain SSD (e.g., 100 cm). That is, the initial phase space file is determined when the distance from the simulated radiation source to the surface of the phantom (e.g., a water phantom) is equal to a certain SSD. The initial phase space file may include information of multiple simulated particles (e.g., electrons and photons), including the energy, position, and velocity vector of each simulated particle. Multiple simulated particles may be used to determine different energy PDD curves. For example, the processing device 140A may calculate different energy PDD curves by inputting the initial phase space file (or information of multiple simulated particles) into software such as DOSXYZnrc software, MCSIM software, etc. The software may output different energy PDD curves.

[0153] In step 820, the processing device 140A (eg, the acquisition module 501) may acquire a measured PDD curve in the phantom corresponding to radiation of the energy spectrum passing through the phantom. The measured PDD curve may be related to the axis of the radiation source.

[0154] When a phantom (e.g., a water phantom) is subjected to the energy spectrum of a radiation source, a measured PDD curve can be physically measured. Specifically, PDD is the ratio of the radiation dose (or referred to as dose) at any depth of the phantom to the dose at a fixed reference depth when a constant SSD (e.g., 100 cm) is used. In some embodiments, the fixed reference depth may be the depth corresponding to the maximum dose. When the SSD is fixed, multiple doses may be measured, each dose corresponding to a depth on the axis of the radiation source (e.g., a depth of 0 cm to 25 cm). In some embodiments, the radiation source may include an electronic confining tube. The radiation field of the radiation source may be determined by the electronic confining tube. The electronic confining tube may be of any size (e.g., 6×6 cm 2 , 10×10cm 2 , 15×15cm 2 , 20×20cm 2 , 25×25cm 2 For example, the size of the electronic light-limiting tube is 10×10cm 2 Processing device 140A may determine a plurality of measured PDDs based on a plurality of doses measured at different depths at a plurality of points along the axis and a dose at a reference point (e.g., a maximum dose point). In some embodiments, the dose may be calculated (e.g., by linear interpolation) from the measured dose of the PDD. Processing device 140A may determine a measured PDD curve based on the measured PDD with or without the calculated PDD.

[0155] In some embodiments, the dose at a point in the phantom may be measured by a dosimeter. For example, the dosimeter may be placed in the radiation field of the radiation source to perform the measurement. In some embodiments, the dosimeter may include a film dosimeter, an ion chamber dosimeter, a diode dosimeter, the like, or any combination thereof.

[0156] In step 830, the processing device 140A (e.g., the determination module 503) may determine a composite PDD curve based on the different energy PDD curves by adjusting at least one initial weight until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold. Each initial weight may correspond to one energy.

[0157] In some embodiments, the processing device 140A may determine the difference between the maximum absolute dose corresponding to the composite PDD curve and the maximum absolute dose corresponding to the measured PDD curve as a first difference. In some embodiments, the processing device 140A may determine the maximum deviation of each simulated PDD from the corresponding measured PDD as a first difference. The processing device 140A may then determine whether the difference is below a first threshold (e.g., 5%, 4%, 3%, 2%, 1%, etc.). In some embodiments, the first threshold may be set according to a default setting of the medical system 100 or by a user or operator through the terminal 130.

[0158] In some embodiments, the processing device 140A may further calculate the average energy of the photons contained in the radiation of the radiation source based on the energy spectrum. The processing device 140A may determine a composite PDD curve based on different energy PDD curves and the average energy of the photons. The initial weight may include multiple weights for different energy PDD curves and a weight for the photons. In some embodiments, the processing device 140A may determine the average energy of the measured photons based on the measured PDD curve. The processing device 140A may determine the weight of the photons based on the calculated average energy and the measured average energy.

[0159] At step 840, the processing device 140A (e.g., the determination module 503) may determine a weight for each of the different energies based on the adjusted weights. The processing device 140A may assign a weight to each of the plurality of PDD curves as a weight for the corresponding energy. The processing device 140A may store the different energies with corresponding weights (and / or weights of photons) associated with the energy spectrum of the radiation source in a storage device (e.g., the storage device 150). In some embodiments, the processing device 140A may retrieve the weights of the different energies and / or photons to determine a target multi-source model.

[0160] It should be noted that the above description of process 800 is provided only for the purpose of illustration, not for limiting the scope of the present disclosure. For people with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, one or more steps can be omitted and / or one or more additional steps can be added. For example, process 800 can also include the step of generating an initial phase space file based on an initial multi-source model. In addition or alternatively, process 800 can also include sending the first difference to a terminal device (e.g., terminal 130) of the user. The user can adjust the weight of each component PDD curve through the terminal device.

[0161] Fig. 9 FIG. 9 is a schematic diagram 900 of an exemplary measured PDD curve and a corresponding composite PDD curve according to some embodiments of the present disclosure. Fig. 9 As shown, curve 901 represents the measured PDD curve corresponding to the energy spectrum of the radiation source, and curve 902 represents the composite PDD curve of the PDD curves of different energies and the average energy of the photons corresponding to the energy spectrum. Fig. 9, the portion in the dashed box 903 can be associated with the average energy of the photons radiated by the radiation source, indicating photon contamination. The portions in the dashed box 907 that are not aligned with each other represent the first difference between the measured PDD curve and the composite PDD curve. When the first difference is lower than a first threshold value (e.g., 5%, 4%, 3%, 2%, 1%), the processing device 140A can determine that the weights corresponding to the component PDD curves reflected in the composite PDD curve are acceptable. The weights corresponding to the component PDD curves determined in this way can be assigned to the corresponding energies, thereby determining the energy spectrum.

[0162] Fig.10 is an exemplary flowchart for determining parameters of a primary virtual source of a target multi-source model according to some embodiments of the present disclosure. In some embodiments, process 1000 may be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140A, processor 210, and / or CPU 340 may execute the instruction set, and when executing the instructions, processing device 140A, processor 210, and / or CPU 340 may be configured to execute process 1000. The steps of the process shown below are for illustration only. In some embodiments, process 1000 may be completed by one or more additional steps not described and / or without one or more steps discussed. In addition, Fig.10 The order of steps of process 1000 shown and described below is not limiting. In some embodiments, parameters of the master virtual source described elsewhere in this disclosure (e.g., Figure 6 Step 630 shown).

[0163] At step 1010, the processing device 140A (eg, the acquisition module 501) may acquire a measured off-axis ratio (OAR) curve corresponding to an energy spectrum of radiation passing through the phantom. The energy spectrum may correspond to an average energy of a radiation source generating the radiation at an energy setting (eg, 12 MeV).

[0164] The OAR is the ratio of the off-axis dose to the axial dose (i.e., the dose at a point on the axis of the radiation source, e.g., axis 412 of treatment head 113) at the same depth of a phantom (e.g., a water tank) within the radiation field. The radiation field can be generated by radiation from the radiation source at an energy setting. For radiation from the radiation source at the same energy setting, the radiation field can depend on the presence and configuration (e.g., structural parameters) of the electronic confinement cylinder of the radiation source and / or a block (e.g., a lead block) operably coupled to the electronic confinement cylinder. In some embodiments, similar to Figure 8Step 820 describes obtaining a measured PDD curve, and multiple OAR values ​​(or simply OAR) at multiple off-axis positions at the same depth (e.g., the depth at which the maximum dose occurs) can be determined based on the doses at the multiple off-axis positions at the same depth and the dose at the axial point. As used herein, different off-axis positions at the same phantom depth (or simply depth) refer to positions on the same plane perpendicular to the axis along the depth of the phantom (coincident with the axis of the radiation source) and at different distances from the axis along the depth of the phantom. The processing device 140A can determine a measured OAR curve based on multiple OARs. In some embodiments, OAR values ​​can be calculated (e.g., by linear interpolation) from the measured OARs. The processing device 140A can determine a measured OAR curve based on the measured OARs with or without calculated OARs.

[0165] At step 1020 , the processing device 140A (eg, the computing module 502 ) may determine / update a simulated OAR curve in the phantom based on initial / updated parameters of the primary virtual source of the initial multi-source model and an initial / updated phase space file of the initial multi-source model.

[0166] The radiation source may include a main source and an electronic limiting light cylinder. The main virtual source of the initial multi-source model may be configured to simulate the main source. The initial phase space file may include information of multiple simulated particles for simulating the radiation of the main source. In some embodiments, the initial (or updated) parameters of the main virtual source may include the size, position, particle flux distribution, etc. of the main virtual source. The size of the main virtual source may refer to the diameter of the main virtual source (e.g., in the range of 0 to 2 mm). The position of the main virtual source may refer to the position of a plane perpendicular to the axis of the radiation source (e.g., Figure 1 The particle flux distribution of the main virtual source may conform to a Gaussian distribution. In some embodiments, the initial parameters of the main virtual source may be determined based on, for example, the structural size and / or structural position of the main source of the radiation source.

[0167] In some embodiments, the initial multi-source model may further include a secondary virtual source configured to simulate an electronic light-limiting cylinder operably coupled to the primary source. The electronic light-limiting cylinder may be of any size (e.g., 6×6 cm2, 10×10 cm 2 , 15×15cm 2 , 20×20cm 2 , 25×25cm 2 For example, the size of the electronic light-limiting tube is 10×10cm 2 The simulated OAR curve can be independent of the size of the electronic light limiting tube.

[0168] In some embodiments, similar to Figure 8The determination of the simulated component PDD curve described in step 810 can be performed by inputting the initial phase space file (or the information of multiple simulated particles in the initial space file) into software such as DOSXYZnrc software, MCSIM software, etc. to determine the simulated OAR curve. The software can output the simulated OAR curve.

[0169] At step 1030 , the processing device 140A (eg, the computing module 502 ) may determine a second difference between the penumbra region of the simulated OAR curve and the penumbra region of the measured OAR curve.

[0170] As described herein, the penumbra region of the OAR curve refers to the width range of the OAR within a threshold range (e.g., 80% to 20%, 90% to 10%, etc.). The processing device 140A may determine the similarity between the penumbra region of the simulated OAR curve and the penumbra region of the measured OAR curve. The processing device 140A may determine a second difference value based on the similarity. In some embodiments, the processing device 140A may determine the maximum deviation of each simulated OAR from the corresponding measured OAR as the second difference value.

[0171] At step 1040, the processing device 140A (e.g., the computing module 502) may determine whether the second difference is below a second threshold. In response to determining that the second difference is not below the second threshold, the processing device 140A may proceed to step 1050. In response to determining that the second difference is below the second threshold, the processing device 140A may proceed to step 1060.

[0172] In some embodiments, the second threshold may be set according to a default setting of the medical system 100 or by a user or operator through the terminal 130 .

[0173] At step 1050 , the processing device 140A (eg, the computing module 502 ) may adjust at least one initial / updated parameter of the primary virtual source.

[0174] In some embodiments, the processing device 140A may receive user input associated with the initial parameters of the primary virtual source through the terminal 130. The processing device 140A may adjust the initial parameters of the primary virtual source according to the user input. In some embodiments, the processing device 140A may automatically adjust the initial parameters of the primary virtual source. Then, the processing device 140A may repeat step 1020 to determine an updated simulated OAR based on the updated parameters of the primary virtual source until the second difference is below the second threshold.

[0175] In step 1060, the processing device 140A (eg, the determination module 503) may determine the parameters of the primary virtual source based on the adjusted initial parameters. The processing device 140A may designate the adjusted initial parameters as the parameters of the primary virtual source.

[0176] In some embodiments, the processing device 140A may store parameters of the master virtual source related to the energy spectrum of the radiation source in a storage device (eg, the storage device 150). The processing device 140A may determine a target multi-source model based on the parameters of the master virtual source.

[0177] It should be noted that the above description of process 1000 is provided only for the purpose of illustration, and is not intended to limit the scope of the present disclosure. For those with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, one or more steps can be omitted and / or one or more additional steps can be added. For example, process 1000 can also include the step of obtaining the structural parameters of the radiation source. Additionally or alternatively, process 1000 can also include the step of generating an initial phase space file based on the initial multi-source model.

[0178] Fig.11 is a flowchart of an exemplary process for determining a correction coefficient corresponding to an electronic light limiting cylinder according to some embodiments of the present disclosure. In some embodiments, process 1100 can be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140A, processor 210, and / or CPU 340 can execute instructions, and when executing instructions, processing device 140A, processor 210, and / or CPU 340 can be configured to execute process 1100. The steps of the process shown below are for illustration only. In some embodiments, process 1100 can be completed by one or more additional steps not described and / or without one or more steps discussed. In addition, Fig.11 The order of steps of the process 1100 shown and described below is not limiting. In some embodiments, the parameters of the correction coefficients of the electronic light-limiting cylinder described elsewhere in the present disclosure (e.g., Figure 6 Step 640 shown).

[0179] In step 1110, the processing device 140A (e.g., the acquisition module 501) may acquire an output factor corresponding to each of the plurality of electronic light limiting cylinders. As used herein, a specific output factor corresponding to a specific electronic light limiting cylinder refers to a ratio of a dose at a maximum dose point measured under the specific electronic light limiting cylinder to a dose at a maximum dose point measured under a reference electronic light limiting cylinder. For example, when the reference electronic light limiting cylinder is 10×10 cm 2 When the dose at the maximum dose point corresponding to the reference electronic light-limiting tube is x, 15×15cm 2 The dose at the maximum dose point corresponding to the electronic light-limiting tube is y, then we can determine that 15×15cm 2 The output factor of the electronic light-limiting tube is For another example, when the reference electronic light-limiting tube is 10×10cm 2 When 10×10cm 2 The output factor of the electronic light limiting tube is 1.

[0180] In some embodiments, different electronic confining cylinders may correspond to different output factors. Each electronic confining cylinder may be operably coupled to the same primary source of a radiation source that produces radiation corresponding to an energy setting (e.g., 12 MeV). The energy setting of the radiation source may correspond to an energy spectrum. The output factor corresponding to the electronic confining cylinder may then be determined at a SSD (e.g., 100 cm).

[0181] In step 1120 , the processing device 140A (eg, the determination module 503 ) may determine a simulation output factor corresponding to each of the plurality of electronic light limiting cylinders based on the structural parameters of the electronic light limiting cylinder.

[0182] The structural parameters of the electronic light-limiting tube may include size, position, etc. or a combination thereof. The size of the electronic light-limiting tube estimated by the size of the opening at the end of the electronic light-limiting tube (for example, 6×6 cm 2 , 10×10cm 2 , 15×15cm 2 In some embodiments, the electronic light limiting cylinder can be operatively connected to a block (e.g., Figure 4 The radiation field of the radiation source may be related to the shape and size of the block. In this case, the structural parameters of the electronic light-limiting cylinder may further include the shape and size of the block.

[0183] The processing device 140A may obtain a specific multi-source model from a storage device (eg, the storage device 150). The specific multi-source model may be similar to Figure 8 or the initial multi-source model described in 10. For example, a specific multi-source model may include a specific primary virtual source for simulating a primary source and a specific secondary virtual source for simulating an electronic light-limiting cylinder of a radiation source. The parameters (e.g., size, size, position) of the specific primary virtual source may be based on Fig.10 The processing device 140A may generate a specific phase space file corresponding to a specific electronic light limiting cylinder based on a specific multi-source model. In some embodiments, similar to Figure 8The determination of the simulated component PDD curve described in step 810, the simulated output factor corresponding to the electronic light limiting cylinder can be determined based on a specific phase space file (or information of multiple simulated particles in a specific phase space file). For example, the simulated output factor corresponding to the electronic light limiting cylinder can be determined by inputting the specific phase space file (or information of multiple simulated particles in a specific phase space file) into software such as DOSXYZnrc software, MCSIM software, etc. The software can output an output factor corresponding to the specific electronic light limiting cylinder.

[0184] In 1130 , the processing device 140A (eg, the determination module 503 ) may determine each correction factor of the plurality of electronic confining cylinders based on the output factor and the simulated output factor.

[0185] As used herein, the correction coefficient of the electronic light-limiting cylinder may be used to correct the output factor corresponding to the second electronic light-limiting cylinder. For example, when the analog output factor of the specific electronic light-limiting cylinder is m and the output factor corresponding to the specific electronic light-limiting cylinder is n, the processing device 140A may determine the correction coefficient of the specific electronic light-limiting cylinder as The processing device 140A may store the correction coefficients for each of the plurality of electronic constrictors for further use, for example, for correcting an output factor of a particular electronic constrictor during treatment using a radiation source with the particular electronic constrictor.

[0186] It should be noted that the above description of process 1100 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. For a person with ordinary skills in the art, various changes or modifications may be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, one or more steps may be omitted and / or one or more additional steps may be added. For example, process 1100 may also include a step for storing information and / or data (e.g., a correction coefficient for each second electronic light-limiting cylinder) in storage device 150.

[0187] Fig.12 is a flowchart of an exemplary process for determining a dose distribution in an object according to some embodiments of the present disclosure. In some embodiments, process 1200 may be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140B, processor 210, and / or CPU 340 may execute instructions, and when executing the instructions, processing device 140B, processor 210, and / or CPU 340 may be configured to perform process 1200. The steps of the process shown below are for illustration only. In some embodiments, process 1200 may be completed by one or more additional steps not described and / or without one or more steps discussed. In addition, Fig.12The order in which the steps of process 1200 are shown and described below is not limiting.

[0188] In step 1210 , the processing device 140B (eg, the acquisition module 504 ) may obtain structural parameters of the electronic light limiting cylinder of the radiation source.

[0189] The radiation source may have an axis perpendicular to the radiation source outlet. The radiation source may also include a primary source. More description of the radiation source may be found elsewhere in this disclosure (e.g., Figure 4 and 6 and its description).

[0190] In some embodiments, the structural parameters of the electronic light-limiting cylinder may include size, position, etc. or any combination thereof. In some embodiments, the position of the electronic light-limiting cylinder may refer to the position of the center point of the electronic light-limiting cylinder along the direction of the radiation source outlet. The size of the end opening of the electronic light-limiting cylinder (for example, 6×6 cm 2 , 10×10cm 2 , 15×15cm 2 In some embodiments, the electronic light limiting cylinder can be operatively connected to a block (e.g., Figure 4 The radiation field of the radiation source may be related to the shape and size of the block. In this case, the structural parameters of the electronic light-limiting cylinder may further include the shape and size of the block.

[0191] In step 1220 , the processing device 140B (eg, the acquisition module 504 ) may acquire a target multi-source model of radiation sources corresponding to the energy spectrum.

[0192] The energy spectrum of the radiation source may correspond to a specific energy setting, such as 6MeV, 12MeV, 18MeV, etc. The radiation source may include multiple energies corresponding to multiple weights. The weights of the multiple energies may correspond to the specific energy setting.

[0193] The target multi-source model may include at least a primary virtual source corresponding to the primary source and a secondary virtual source corresponding to the electronic light limiting tube. The primary virtual source may be a first point source, and the secondary virtual source may include a second point source and a surface source. For example, the electronic light limiting tube includes an upper portion, a middle portion, and a lower portion, and the second point source may correspond to the upper portion and the middle portion of the electronic light limiting tube. The surface source may correspond to the lower portion of the electronic light limiting tube. More description of the target multi-source model of radiation sources may be found elsewhere in this disclosure (e.g., Figure 6 and 7 and its related description).

[0194] In step 1230 , the processing device 140B (eg, the determination module 505 ) may determine a phase space file containing information of a plurality of simulated particles corresponding to the radiation based on the target multi-source model and the structural parameters of the electronic confining cylinder.

[0195] As used herein, radiation from a radiation source refers to electrons and / or photons that pass through an object from an end opening of an electronic light-limiting tube. In some embodiments, radiation from a radiation source may include primary electrons, photons, and secondary electrons. Primary electrons and photons may be generated by a primary source. Primary electrons may include a first portion and a second portion that leave the radiation source without being scattered in the radiation source. Secondary electrons may be generated by the second portion of primary electrons striking the electronic light-limiting tube. The first portion of simulated particles may correspond to the first portion of primary electrons, the second portion of simulated particles may correspond to photons, and the third portion of simulated particles may correspond to secondary electrons.

[0196] In some embodiments, the information of the plurality of simulated particles contained in the phase space file may include the position, direction, energy, etc. of each of the plurality of simulated particles. In some embodiments, the processing device 140B may input the structural parameters of the electronic light limiting cylinder into the target multi-source model. The simulated particles in the phase space file may be determined based on direct sampling (e.g., random direct sampling). More descriptions on determining the phase space file corresponding to the radiation source may be found elsewhere in the present disclosure (e.g., Fig.13 and its related description).

[0197] At step 1240 , the processing device 140B (eg, the acquisition module 504 ) may acquire a transmission model of the energy spectrum radiation passing through the object.

[0198] The transport model may be configured to simulate particle transport of a plurality of simulated particles. In some embodiments, the transport model may include a Monte Carlo (MC) algorithm, a Voxel Monte Carlo (VMC) algorithm, a Macro Monte Carlo (MMC) algorithm, or the like, or any combination thereof.

[0199] At step 1250 , the processing device 140B (eg, the determination module 505 ) may determine a dose distribution in the object based on the phase space file and the transmission model.

[0200] In some embodiments, the processing device 140B may input a phase space file (or information of multiple simulated particles) into the transmission model. In some embodiments, the energy spectrum of the radiation source, the spatial distribution of simulated particles in the radiation field of the radiation source, the angular distribution, etc. may be input into the transmission model. According to the input information, the transmission of multiple simulated particles may be simulated based on the transmission model. Then, the transmission model may output multiple doses at multiple positions in an object (e.g., a patient) corresponding to the electronic light limiting cylinder. The processing device 140B may determine the dose distribution (e.g., a 3D dose distribution) in the object based on the multiple doses. In some embodiments, the processing device 140B may determine the corrected dose for each of the multiple positions in the object based on the correction coefficient corresponding to the electronic light limiting cylinder. The determination of the correction coefficient corresponding to the electronic light limiting cylinder may be combined with Fig.11 Then, the processing device 140B may determine an updated dose distribution in the object based on the corrected dose. The processing device 140B may determine the updated dose distribution as the dose distribution of the object. In some embodiments, the dose distribution in the object may be represented by a plurality of dose distribution curves (e.g., Fig.14 Dose distribution curve shown).

[0201] It should be noted that the above description of process 1200 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. For a person with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, one or more steps can be omitted and / or one or more additional steps can be added. For example, process 1200 may also include a step for acquiring a CT image of an object (e.g., a patient) to determine the shape of a region of interest (ROI). Additionally or alternatively, process 1200 may also include transmitting the dose distribution of the object to a user's terminal device (e.g., terminal 130). The user can view the dose distribution through the terminal device for further treatment.

[0202] Fig.13 1300 is a flowchart of an exemplary process for determining a phase space file of a target multi-source model according to some embodiments of the present disclosure. In some embodiments, process 1300 may be implemented as a set of instructions (e.g., an application) stored in storage device 150, memory 220, or memory 390. Processing device 140B, processor 210, and / or CPU 340 may execute instructions, and when executing instructions, processing device 140B, processor 210, and / or CPU 340 may be configured to execute process 1300. The steps of the process shown below are for illustration only. In some embodiments, process 1300 may be completed by one or more additional steps not described and / or without one or more steps discussed. In addition, Fig.13 The order of the steps of process 1300 shown and described below is not limiting. Step 1230 in process 1200 can be implemented by executing one or more steps of process 1300.

[0203] Combination Figure 6As described, the target multi-source model of the radiation source may include a target phase space file. Since the target multi-source model is determined based on a reference electronic limiting cylinder, the target phase space file may be associated with the reference electronic limiting cylinder. If the electronic limiting cylinder of the main source operably coupled to the radiation source is the same as the reference electronic limiting cylinder, the processing device 140B may designate the target phase space file as the phase space file to determine the dose distribution in the object. Alternatively, if the electronic limiting cylinder is different from the reference electronic limiting cylinder, the processing device 140B may determine the phase space file, in particular the information of multiple simulated particles of the phase space file, based on the target phase space file and the structural parameters of the electronic limiting cylinder according to process 1300.

[0204] In step 1310 , the processing device 140B (eg, the determination module 505 ) may determine the positions and directions of the plurality of simulated particles based on the structural parameters of the electronic confining cylinder.

[0205] Similar to the initial phase space file described in step 610, the plurality of simulated particles in the phase space file may include a first portion corresponding to primary electrons that are not scattered in the radiation source, a second portion corresponding to photons, and a third portion corresponding to secondary electrons corresponding to the electronic light limiting tube. The second portion of simulated particles may include a first sub-portion of simulated particles corresponding to a second point source of the target multi-source model and a second sub-portion of simulated particles corresponding to a surface source of the target multi-source model.

[0206] Similar to the determination of the initial phase space file described in step 610, for each of the first portion of simulated particles, the processing device 140B can determine the position and direction of the simulated particles by a fourth direct sampling based on a seventh distribution function (e.g., a fifth Gaussian function) in a manner similar to step 610. For each of the first sub-portion of the simulated particles, the processing device 140B can determine the position and direction of the simulated particles by a fifth direct sampling based on an eighth distribution function (e.g., a sixth Gaussian function). For each of the second sub-portion of the simulated particles, the processing device 140B can determine the position and direction of the simulated particles by a sixth distribution function based on a ninth distribution function (e.g., a third uniform distribution function). In some embodiments, the processing device 140B can specify the position and direction of the first portion of the simulated particles in the target phase space file as the position and direction in the phase space file, which is similar to the determination of the initial phase space file in step 610.

[0207] In step 1320 , the processing device 140B (eg, the determination module 505 ) may determine particle energies of the plurality of simulated particles based on the target multi-source model.

[0208] In some embodiments, the processing device 140B may obtain an energy spectrum from a target phase space file of the target multi-source model. The processing device 140B may determine the particle energy of one of the plurality of simulated particles from the energy spectrum by direct sampling based on weights of different energies. That is, the higher the weight of an energy, the higher the probability that the energy is sampled. For example, the processing device 140B may sample the energy spectrum based on the weights, and determine the particle energy of one of the plurality of simulated particles based on the sampling.

[0209] At step 1330 , the processing device 140B (eg, the determination module 505 ) may determine a phase space file based on the position, direction, and energy.

[0210] In some embodiments, the processing device 140B may update the target phase space file based on the position, direction, and energy of the particle. The processing device 140B may designate the updated target phase space file as the phase space file.

[0211] It should be noted that the above description of process 600 is provided only for the purpose of illustration, and not for limiting the scope of the present disclosure. For those with ordinary skills in the art, various changes or modifications can be made according to the teachings of the present disclosure. However, these changes and modifications do not depart from the scope of the present disclosure. In some embodiments, process 1300 may include one or more additional steps. For example, a step for updating the parameters of the secondary virtual source in the target phase space file of the target multi-source model can be added before step 1330 of process 1300. The parameters of the secondary virtual source can be updated according to the structural parameters of the electronic light-limiting tube. The processing device 140B can further determine the phase space file based on the updated parameters of the secondary virtual source. In some embodiments, a step of process 1300 can be implemented by executing two sub-steps. For example, the processing device 140B can determine the positions of multiple simulated particles and the directions of multiple simulated particles respectively.

[0212] Fig.14 is a schematic diagram of an example dose distribution curve in a phantom according to some embodiments of the present disclosure. Fig.14 As shown, curves 1401, 1402, 1403, 1404, 1405, 1406, 1407, 1408, and 1409 represent different dose distribution curves, and each dose distribution curve corresponds to a depth of the phantom. Fig.14 , a line passing through the central axes of different dose distribution curves may have multiple intersections with the dose distribution curves. The processing device 140B may determine a PDD curve based on the corresponding doses of the multiple intersections.

[0213] The basic concepts have been described above. Obviously, for those of ordinary skill in the art who have read this application, the above invention disclosure is only for example and does not constitute a limitation of this application. Although not explicitly stated here, those of ordinary skill in the art may make various modifications, improvements and amendments to this application. Such modifications, improvements and amendments are suggested in this application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of this application.

[0214] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0215] In addition, it will be appreciated by those skilled in the art that various aspects of the present application may be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product, or combination of substances, or any new and useful improvements thereto. Therefore, various aspects of the present application may be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or by combining software and hardware implementations, which are generally referred to herein as "units," "modules," or "systems." In addition, various aspects of the present application may take the form of a computer program product embodied in one or more computer-readable media having computer-readable program code embodied thereon.

[0216] A computer readable signal medium may include a propagated data signal containing computer program code, for example, in baseband or as part of a carrier wave. Such propagated signals may be in a variety of forms, including electromagnetic, optical, etc., or any suitable combination. A computer readable signal medium may be any computer readable medium other than a computer readable storage medium, which may be connected to an instruction execution system, device or apparatus to communicate, propagate or transmit a program for use. The program code on a computer readable signal medium may be propagated via any suitable medium, including radio, cable, fiber optic cable, RF, etc., or any combination of the above.

[0217] Computer program code for performing the operations of various aspects of the present application may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C, C++. The program code may be executed entirely on a user's computer, partially on a user's computer as a standalone software package, partially on a user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., by using a network service provider's network) or provide services in a cloud computing environment, such as software as a service (SaaS).

[0218] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this application, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this application. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this application. For example, although the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a pure software solution, for example, installation on an existing server or mobile device.

[0219] Similarly, it should be noted that in order to simplify the description disclosed in this application and thus facilitate the understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of the present application, multiple features are sometimes grouped into one embodiment, figure, or description thereof. However, this method of the present application should not be interpreted as reflecting the intention that the claimed object material to be scanned requires more features than those expressly stated in each claim. On the contrary, the subject matter of the invention should have fewer features than the single embodiment described above.

Claims

1. A system for modeling a radiation source, include: a storage device for storing a set of instructions for modeling a radiation source configured to emit radiation including an energy spectrum of different energies; as well as at least one processor in communication with the storage device, wherein when executing the instructions, the at least one processor is configured to cause the system to perform operations comprising: Acquire an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, and the initial phase space file includes information of the multiple simulated particles of different energies; calculating different energy percentage depth dose (PDD) curves in a phantom based on the initial phase space file, wherein each of the different energy PDD curves corresponds to one of the different energies; obtaining a measured PDD curve in the phantom corresponding to the radiation of the energy spectrum passing through the phantom; For each of the different energies, determining a weight of each energy based on the different energy PDD curve and the measured PDD curve, comprising: determining, based on the different energy PDD curves, the composite PDD curve by adjusting at least one of a set of initial weights until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold; and determining the weight of each of the different energies based on the adjusted weights; the weight representing a percentage of the simulated particles of each energy among the plurality of simulated particles present in the radiation; and A target multi-source model of the radiation sources corresponding to the energy spectrum is determined based at least in part on the initial multi-source model and the weights.

2. The system according to claim 1, It is characterized in that The initial phase space file includes the set of initial weights, wherein each of the initial weights corresponds to one of the different energies.

3. The system according to claim 1, It is characterized in that The radiation source includes a main source and an electronic light-limiting cylinder, and The radiation includes primary electrons and secondary electrons. The primary electrons are generated by the main source. The primary electrons include a first part and a second part. The first part of the primary electrons leaves the radiation source without being scattered. The secondary electrons are generated by the second part of the primary electrons hitting the electronic light limiting cylinder.

4. The system according to claim 3, It is characterized in that The first portion of the simulated particles corresponds to the first portion of the primary electrons.

5. The system according to claim 4, It is characterized in that The radiation also includes photons, and A second portion of the simulated particles corresponds to the photons.

6. The system according to claim 5, It is characterized in that The photons are generated by the primary source.

7. The system according to claim 5, It is characterized in that The initial multi-source model of the radiation source includes a main virtual source for simulating the main source, the main virtual source corresponding to the first part of the simulated particles and the second part of the simulated particles.

8. The system according to claim 7, It is characterized in that The primary virtual source is a point source.

9. The system according to claim 7, It is characterized in that The initial phase space file includes a position of the first portion of the simulated particles and an orientation of the first portion of the simulated particles.

10. The system according to claim 9, It is characterized in that The position of the first portion of the simulated particles or the direction of the first portion of the simulated particles is determined based on direct sampling of a first distribution function, and the particle flux distribution of the first portion of the simulated particles on a plane perpendicular to the axis of the main virtual source conforms to the first distribution function.

11. The system according to claim 10, It is characterized in that The first distribution function is a first Gaussian function.

12. The system according to claim 7, It is characterized in that A third portion of the simulated particles corresponds to the secondary electrons, and The initial multi-source model of the radiation source includes a secondary virtual source for simulating the electronic light limiting cylinder, and the secondary virtual source corresponds to the third part of the simulated particles.

13. The system according to claim 12, It is characterized in that The secondary virtual source includes at least one of a second point source or a surface source.

14. The system according to claim 12, It is characterized in that The initial phase space file includes a position of the third portion of the simulated particle and an orientation of the third portion of the simulated particle.

15. The system according to claim 13, It is characterized in that The third portion of the simulated particles includes a first sub-portion of the simulated particles corresponding to the second point source and a second sub-portion of the simulated particles corresponding to the surface source. The position of the first subportion of the simulated particles or the direction of the first subportion of the simulated particles is determined based on a second direct sampling of a second distribution function, wherein a particle flux distribution of the first subportion of the simulated particles on a second plane perpendicular to the axis of the main virtual source conforms to the second distribution function, and The position of the second sub-portion of the simulated particle or the direction of the second sub-portion of the simulated particle is determined based on a third direct sampling of a third distribution function, wherein the particle flux distribution of the second sub-portion of the simulated particle on a third plane perpendicular to the axis of the main virtual source conforms to the third distribution function.

16. The system according to claim 15, It is characterized in that The second distribution function is a second Gaussian function, and the third distribution function is a uniform distribution function.

17. The system according to claim 7, It is characterized in that The at least one processor is further configured to cause the system to perform operations including: acquiring a measured off-axis ratio (OAR) curve corresponding to the radiation of the energy spectrum passing through the phantom; determining a simulated OAR curve in the phantom based on the primary virtual source parameters of the initial multi-source model and the initial phase space file; adjusting the main virtual source parameters until a second difference between the penumbra region of the simulated OAR curve and the penumbra region of the measured OAR curve is below a second threshold; and Further, based on adjusting the main virtual source parameters, the target multi-source model of the radiation source is determined.

18. The system according to claim 17, It is characterized in that The main virtual source parameters include at least one of a size of the main virtual source, a vertical position of the main virtual source along an axis of the main virtual source, or a particle flux distribution of the main virtual source.

19. The system according to claim 3, It is characterized in that The primary source is configured to be operably coupled to one of a plurality of second electronic light limiting cylinders, and The at least one processor is further configured to cause the system to perform operations including: For each of the plurality of second electronic light-limiting cylinders, Acquire an output factor corresponding to the second electronic light-limiting cylinder; determining a simulation output factor corresponding to the second electronic light-limiting cylinder based on the structural parameters of the second electronic light-limiting cylinder; and Based on the output factor and the simulated output factor, a correction coefficient of the second electronic light limiting cylinder is determined.

20. The system according to claim 1, It is characterized in that The radiation source is a linear accelerator.

21. The system according to claim 5, It is characterized in that The at least one processor is further configured to cause the system to perform operations including: Calculating the average energy of the photons based on the energy spectrum; determining a measured average energy of the photons based on the measured PDD curve; determining a weight of the photon based on a ratio between the measured average energy and the calculated average energy; and The target multi-source model is determined further based on the weights of the photons.

22. The system according to claim 13, It is characterized in that The electronic light-limiting tube at least comprises an upper portion, a middle portion and a lower portion. The second point source corresponds to the upper part and the middle part of the electronic light limiting cylinder, and The surface source corresponds to the lower portion of the electronic light-limiting cylinder.

23. The system according to claim 1, It is characterized in that The radiation source includes a collimating assembly, and The initial multi-source model of the radiation sources also includes a third virtual source corresponding to the collimation assembly.

24. The system according to claim 23, It is characterized in that The third virtual source is a line source.

25. A method for modeling a radiation source, the radiation source being configured to emit radiation having a spectrum of different energies, the method being implemented on a computing device comprising at least one processor and at least one storage device, the method include: Acquire an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, and the initial phase space file includes information of the multiple simulated particles of different energies; calculating different energy percentage depth dose (PDD) curves in a phantom based on the initial phase space file, wherein each of the different energy PDD curves corresponds to one of the different energies; obtaining a measured PDD curve in the phantom corresponding to the radiation of the energy spectrum passing through the phantom; For each of the different energies, determining a weight of each energy based on the different energy PDD curve and the measured PDD curve, comprising: determining, based on the different energy PDD curves, the composite PDD curve by adjusting at least one of a set of initial weights until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold; and determining the weight of each of the different energies based on the adjusted weights; the weight representing a percentage of the simulated particles of each energy among the plurality of simulated particles present in the radiation; and A target multi-source model of the radiation sources corresponding to the energy spectrum is determined based at least in part on the initial multi-source model and the weights.

26. A system for modeling a radiation source, the radiation source being configured to emit radiation comprising a spectrum of different energies, include: an acquisition module, configured to acquire an initial multi-source model of the radiation source, wherein the initial multi-source model comprises an initial phase space file, the initial phase space file comprises information of the plurality of simulated particles of different energies, and a measured PDD curve corresponding to the radiation of the energy spectrum passing through the phantom in the phantom; a calculation module for calculating different energy percentage depth dose (PDD) curves in a phantom based on the initial phase space file, wherein each of the different energy PDD curves corresponds to one of the different energies; and A determination module, for determining, for each of the different energies, a weight of each energy based on the different energy PDD curve and the measured PDD curve, comprising: determining, based on the different energy PDD curves, the composite PDD curve by adjusting at least one of a set of initial weights until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold; and Based on the adjusted weights, the weight of each of the different energies is determined; the weight represents the percentage of the simulated particles of each energy among the multiple simulated particles present in the radiation, and is used to determine a target multi-source model of the radiation sources corresponding to the energy spectrum based at least in part on the initial multi-source model and the weights.

27. A non-transitory computer readable medium comprising executable instructions which, when executed by at least one processor, direct the at least one processor to perform a method for simulating a radiation source, the radiation source being configured to emit radiation having a spectrum of different energies, the method include: Acquire an initial multi-source model of the radiation source, wherein the initial multi-source model includes an initial phase space file, and the initial phase space file includes information of the multiple simulated particles of different energies; calculating different energy percentage depth dose (PDD) curves in a phantom based on the initial phase space file, wherein each of the different energy PDD curves corresponds to one of the different energies; acquiring, in the phantom, a measured PDD curve corresponding to the radiation of the energy spectrum passing through the phantom; For each of the different energies, determining a weight of each energy based on the different energy PDD curve and the measured PDD curve, comprising: determining, based on the different energy PDD curves, the composite PDD curve by adjusting at least one of a set of initial weights until a first difference between the composite PDD curve and the measured PDD curve is below a first threshold; and determining the weight of each of the different energies based on the adjusted weights; the weight representing a percentage of the simulated particles of each energy among the plurality of simulated particles present in the radiation; and A target multi-source model of the radiation sources corresponding to the energy spectrum is determined based at least in part on the initial multi-source model and the weights.

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