Intensity modulated x-ray flash radiotherapy planning system and method

Abstract

This invention provides a compensator-modulated intensity-modulated (IMIM) X-ray flash radiotherapy system and method, belonging to the field of radiotherapy equipment control technology. The system includes a patient data management module for acquiring basic patient information, image data, and radiotherapy plan data; a region of interest (ROI) determination module for identifying the RIO region; and an IMIM-modulated flash planning module for calculating the effective flash dose and obtaining the optimal IMIM-modulated X-ray flash plan based on clinical requirements. This invention enables the calculation of effective doses for different flash effect models and optimizes the IMIM-modulated X-ray flash plan using a step-by-step or synchronous approach. It provides technical conditions for realizing IMIM-modulated X-ray radiotherapy and its clinical application, filling a gap in X-ray flash radiotherapy technology and holding significant importance for the translational application of flash radiotherapy technology.

Description

Technical Field

[0001] This invention relates to the field of radiotherapy equipment control technology, specifically to an X-ray Flash radiotherapy planning system and method with intensity modulated compensator. Background Technology

[0002] High-dose-rate radiotherapy (FLASH) is an emerging radiotherapy technique defined as irradiation using a dose rate exceeding 40 Gy / s. Its main characteristic is that, compared to conventional radiotherapy, it significantly reduces damage to normal tissues while maintaining the therapeutic effect on tumors. The protective effect of FLASH radiotherapy was initially discovered in the 1950s and 60s, but research stagnated for approximately 40 years due to technological and cognitive limitations. In 2014, Favaudon et al. at the Curie Institute in France rediscovered this radiation-protective effect and named it the FLASH effect. Subsequently, multiple animal model studies have validated the protective effect of high-dose-rate radiotherapy on normal tissues. The human trial FAST-01 conducted at Cincinnati Children's Hospital in the United States also showed that FLASH radiotherapy is comparable to conventional dose-rate radiotherapy in pain relief and is clinically feasible and safe. These studies indicate that FLASH radiotherapy, due to its extremely short radiation delivery time, alters the biological effects of conventional radiotherapy on normal tissues, while also addressing organ movement management issues and potentially offering economic benefits, improving patient comfort and treatment efficiency.

[0003] Depending on the type of radiation used, flash radiotherapy techniques can be divided into proton flash, electron flash, and X-ray flash. Currently, X-rays are the most widely used in radiotherapy, hence X-ray flash technology has received widespread attention. Based on the implementation method, X-ray flash radiotherapy techniques can be divided into open-field irradiation, conformal irradiation, and intensity-modulated radiation therapy. Open-field X-ray flash irradiation primarily uses tungsten gates to form irradiation fields of fixed shapes and different sizes. Because the field shape formed by this technique is simple, it cannot address the complex anatomical structures of patients and is therefore only used in clinical trials. Conformal X-ray flash irradiation can use multi-leaf collimators to conform the field to the target area shape, or custom-designed baffles for conformal irradiation. This technique can be used to treat tumors with relatively simple geometric relationships between the target area and organs at risk, but it cannot protect normal organs embedded within or surrounded by the tumor, nor can it achieve localized dose boosting to the tumor target area. Intensity-modulated X-ray flash irradiation can not only achieve conformal targeting of the tumor target area, but also effectively protect normal organs embedded in or surrounded by the tumor, while simultaneously achieving localized dose boosting of the tumor target area. However, no researchers have yet proposed a feasible method for intensity-modulated X-ray flash radiotherapy. This is mainly because flash radiotherapy requires beam exit within an extremely short time (approximately tens of milliseconds), and existing X-ray intensity-modulated techniques using multi-leaf collimators are insufficient to adjust the leaf positions within such a short time.

[0004] Currently, X-ray flash radiotherapy can only be used for conformal radiotherapy, not intensity-modulated radiotherapy (IMRT). This is mainly because using traditional multi-leaf collimators for X-ray flash IMRT requires a number of leaflets and a dose rate change rate that far exceed the engineering limits. This affects the quality of X-ray flash radiotherapy planning and limits the effectiveness of the flash protection effect.

[0005] To implement intensity-modulated X-ray flash radiotherapy (IMRT), a corresponding planning system is required. This system should not only possess the functions of a conventional X-ray radiotherapy planning system but also have the capability to design plans for compensator-modulated X-ray flash radiotherapy. Specifically, it should include a bio-dosage calculation model considering the flash protection effect, an optimization algorithm for compensator-modulated X-ray flash radiotherapy planning, an interactive interface for inputting flash radiotherapy planning optimization parameters, and a data interface capable of outputting compensator thickness stepwise data. Only with this system can the clinical application of compensator-modulated X-ray flash radiotherapy be promoted. However, existing planning systems do not possess the capability to design plans for intensity-modulated X-ray flash radiotherapy. Summary of the Invention

[0006] The purpose of this invention is to provide an X-ray Flash radiotherapy planning system and method with compensator intensity modulation, which improves the quality of X-ray Flash radiotherapy planning and enhances the treatment effect, thereby solving at least one of the technical problems existing in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a compensator-modulated X-ray flash radiotherapy planning system, comprising:

[0009] The patient data management module is used to obtain basic patient information, patient imaging data, and patient radiotherapy plan data;

[0010] The region of interest (ROI) determination module is used to determine the ROI for radiotherapy.

[0011] The Flash planning module for intensity-modulated compensator is used to calculate the effective Flash dose based on the planning parameters and the patient's planned CT scan. Based on the set planning parameters, the effective Flash dose is calculated, and the optimal Flash planning parameters are generated.

[0012] As a further limitation of the first aspect of the invention, the calculation of the effective Flash dose based on the planning parameters and the patient's planned CT scan includes:

[0013] The instantaneous intensity distribution of the beam after passing through the compensator is as follows:

[0014]

[0015] Where i represents the field number, t represents the healing time, and m i (t) represents the instantaneous machine dose rate as a function of time, S i Indicates the geometric parameters of the shooting field. and The thickness distribution and density information of the compensator are represented; F is a function used to calculate the intensity distribution using the dose engine of a conventional X-ray radiotherapy planning system. S (t) represents the time-varying instantaneous intensity distribution generated by the Flash accelerator head;

[0016] Therefore, the distribution of physical doses in the patient's body over time is as follows:

[0017]

[0018] I ct The image represents the planned CT image, where D is a function used by the dose engine of a conventional X-ray radiotherapy planning system to calculate the physical dose distribution within the patient; G i This indicates the angle of the firing field; D phy(t) is converted into the Flash effective dose D using the following formula. FE (t):

[0019] D FE =∫M·dD phy .

[0020] As a further limitation of the first aspect of the present invention, combining the expected clinical goals of clinical target coverage and protection of organs at risk, the objective function of the planning optimization model is expressed as:

[0021]

[0022]

[0023] Where f is the overall objective function to be optimized, Obj i with w T,i Let represent the dose objective function and corresponding weights for the i-th tumor target region, respectively; N represents the total number of radiation fields; Res(P) function is the constraint function for the parameters to be optimized; and P represents the parameters to be optimized. This refers to the strictly controlled dose limits that must not be exceeded to ensure treatment safety. (T) forced Then it is the corresponding threshold.

[0024] As a further limitation of the first aspect of the present invention, if a Flash effective dose calculation model that depends only on dose rate is adopted, then the dose correction factor matrix is:

[0025]

[0026] Where d is a 3×1 vector representing the spatial coordinates of a voxel, and R min p is a constant less than 0 and greater than 1, representing the minimum dose rate required to trigger the Flash protection effect.

[0027] As a further limitation of the first aspect of the present invention, if a Flash effective dose calculation model dependent on dose and dose rate threshold is adopted, the dose correction factor matrix is ​​expressed as:

[0028]

[0029] Among them, D min This indicates the minimum cumulative dose required to trigger the Flash protection effect.

[0030] Secondly, the present invention provides a method for planning X-ray flash radiotherapy with intensity modulation by a compensator, comprising:

[0031] Obtain the patient's basic information, patient imaging data, and patient radiotherapy plan data;

[0032] Identify the region of interest for radiotherapy;

[0033] The effective Flash dose is calculated based on the planning parameters and the patient's planned CT scan. The optimal Flash planning parameters are then calculated based on the set planning parameters and the calculated effective Flash dose.

[0034] As a further limitation of the second aspect of the invention, the calculation of the effective Flash dose based on the planning parameters and the patient's planned CT scan includes:

[0035] The instantaneous intensity distribution of the beam after passing through the compensator is as follows:

[0036]

[0037] Where i represents the field number, t represents the healing time, and m i (t) represents the instantaneous machine dose rate as a function of time, S i Indicates the geometric parameters of the shooting field. and The thickness distribution and density information of the compensator are represented; F is a function used to calculate the intensity distribution using the dose engine of a conventional X-ray radiotherapy planning system. S (t) represents the time-varying instantaneous intensity distribution generated by the Flash accelerator head;

[0038] Therefore, the distribution of physical doses in the patient's body over time is as follows:

[0039]

[0040] I ct The image represents the planned CT image, where D is a function used by the dose engine of a conventional X-ray radiotherapy planning system to calculate the physical dose distribution within the patient; G i This indicates the angle of the firing field; D phy (t) is converted into the Flash effective dose D using the following formula. FE (t):

[0041] D FE =∫M·dD phy .

[0042] As a further limitation of the second aspect of the invention, combining the expected clinical goals of clinical target coverage and organ at risk protection, the objective function of the planning optimization model is expressed as:

[0043]

[0044] Where f is the overall objective function to be optimized, Obj i with w T,iLet represent the dose objective function and corresponding weights for the i-th tumor target region, respectively; N represents the total number of radiation fields; Res(P) function is the constraint function for the parameters to be optimized; and P represents the parameters to be optimized. This refers to the strictly controlled dose limits that must not be exceeded to ensure treatment safety. (T) forced Then it is the corresponding threshold.

[0045] As a further limitation of the second aspect of the present invention, if a Flash effective dose calculation model that depends only on dose rate is adopted, then the dose correction factor matrix is:

[0046]

[0047] Where d is a 3×1 vector representing the spatial coordinates of a voxel, and R min p is a constant less than 0 and greater than 1, representing the minimum dose rate required to trigger the Flash protection effect.

[0048] As a further limitation of the second aspect of the present invention, if a Flash effective dose calculation model dependent on dose and dose rate threshold is adopted, the dose correction factor matrix is ​​expressed as follows:

[0049]

[0050] Among them, D min This indicates the minimum cumulative dose required to trigger the Flash protection effect.

[0051] The beneficial effects of this invention are as follows: This invention proposes a compensator-modulated X-ray flash radiotherapy method and system, which realizes the calculation of effective dose for different flash effect models and optimizes the compensator-modulated X-ray flash plan using a step-by-step or synchronous approach; it provides technical conditions for realizing X-ray flash intensity-modulated radiotherapy and its clinical application; it fills the gap in X-ray flash radiotherapy technology, which is of great significance for the transformation and application of flash radiotherapy technology and improving the level of cancer treatment.

[0052] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1This is a functional principle framework diagram of the X-ray Flash radiotherapy planning system with compensator intensity modulation according to an embodiment of the present invention.

[0055] Figure 2 This is a schematic diagram of the compensator-modulated X-ray flash radiotherapy principle according to an embodiment of the present invention.

[0056] Figure 3 This is a schematic diagram illustrating the relationship between the effective Flash dose and the physical dose, which depends on the dose rate threshold, as described in an embodiment of the present invention.

[0057] Figure 4 This is a schematic diagram illustrating the relationship between physical dose and effective Flash dose in an X-ray Flash program comprising three radiation fields, as described in an embodiment of the present invention. Detailed Implementation

[0058] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0059] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0060] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0061] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0062] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0063] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0064] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0065] This invention provides an X-ray flash radiotherapy technology using intensity-modulated X-ray therapy (IMRT) with compensators, designs an optimization model for X-ray flash radiotherapy planning, and designs a complete set of IMRT flash radiotherapy planning systems.

[0066] The compensator in this invention is made of a high-density material (such as copper or lead), which can effectively attenuate the intensity of the X-ray beam, thereby reducing the dose in the area through which the X-rays pass. Figure 1 As shown, because the required dose reduction varies in different regions, the compensator is manufactured with a non-uniform thickness. During radiotherapy, the X-ray flash beam is attenuated to varying degrees as it passes through different parts of the compensator due to the different thicknesses, resulting in a change in beam intensity distribution and thus achieving intensity modulation of the X-ray flash beam. Furthermore, the dose rate of the beam decreases after intensity modulation by the compensator, while the flash protection effect generally requires a dose rate ≥40 Gy / s. Therefore, unlike conventional dose radiotherapy, the compensator thickness in X-ray flash radiotherapy cannot be too thick to ensure that the dose rate of the intensity-modulated beam meets the requirements of flash technology.

[0067] This paper proposes a method for designing X-ray flash radiotherapy plans using intensity-modulated (IMM) radiation therapy with compensators. This method employs an inverse optimization approach. Regarding the objective function, since the flash protection effect is related to the continuous cumulative dose and dose rate, this invention first calculates the physical dose distribution and dose rate distribution within the patient. Then, based on the flash effect model, the physical dose in the traditional optimization algorithm is converted into the effective flash dose. Finally, the objective functions for the tumor target area and various organs at risk are calculated based on the effective flash dose distribution, thereby maximizing the flash protection effect.

[0068] A compensator-modulated X-ray flash radiotherapy planning system is proposed. This system adds X-ray flash radiotherapy planning functionality to the existing conventional dose-rate X-ray radiotherapy planning system. Furthermore, the system supports two types of X-ray flash planning: conformal X-ray flash planning using a multi-leaf collimator and compensator-modulated X-ray flash planning. Finally, in addition to outputting standard Dicom RT planning data, the system can also output compensator thickness distribution information to create the compensator required for intensity-modulated flash planning.

[0069] The following section, based on literature retrieved (currently, there are no patents for X-ray flash with compensator modulation), further compares and explains the limitations of existing flash radiotherapy methods and the innovative aspects of this invention:

[0070] Firstly, in proton flash radiotherapy, existing technologies mainly include shot-through and conformal flash. Shot-through uses high-energy proton beams to penetrate the patient's body and relies entirely on the flash effect to protect organs at risk. This technique does not need to consider the uncertainty of the Bragg peak position, but correspondingly, it cannot fully utilize the advantage of the rapid drop in proton dose. Conformal flash uses a spine filter to modulate the intensity of the proton beam, achieving intensity-modulated proton flash radiotherapy. However, both of these methods require large and expensive proton radiotherapy systems, resulting in high equipment costs. Electron flash can use multi-leaf collimators for conformal radiotherapy, but the planning quality still needs improvement. In addition, electron flash can also use compensators to achieve intensity-modulated radiotherapy, but compensators cause a rapid reduction in the maximum range of the electron beam, making it difficult to apply to deeper tumor targets. Compared to the technologies mentioned above, the compensator-modulated X-ray flash radiotherapy technology constructed in this invention does not require the high equipment cost of proton flash; in addition, due to the strong penetrating power of X-rays, it does not have the problem of being unable to treat deeper target areas like electron flash; finally, compared to conformal X-ray flash radiotherapy, this invention can achieve better planning quality.

[0071] This invention provides a method and system for intensity-modulated X-ray flash radiotherapy with compensators, providing comprehensive technical support for the effective implementation of X-ray flash radiotherapy and promoting its clinical application.

[0072] In this embodiment, as Figure 2 As shown, a compensator-modulated X-ray Flash radiotherapy planning system is first presented. Similar to conventional dose-rate planning systems, this system includes a patient data management module to manage basic patient information, patient imaging data, and patient planning data. The region of interest (ROI) delineation module allows physicians or physicists to manually or automatically delineate the target area, organs at risk, and other contours. Subsequently, the patient's planning CT scans and the delineated ROI information can be used for planning.

[0073] Based on clinical needs, the planning system described in this embodiment can design three types of plans: 1) A conventional dose rate planning module includes three sub-modules: conventional dose rate planning parameter input, physical dose calculation, and conventional dose rate planning reverse optimization. This module can realize the design of traditional conventional dose IMRT or VMAT radiotherapy plans; 2) An MLC conformal Flash planning module includes two sub-modules: parameter input and Flash effective dose calculation. The parameter input sub-module mainly provides users with an interactive interface for inputting conformal Flash parameters such as gantry angle, dose rate range, and conformal boundary magnification. The Flash effective dose calculation sub-module calculates the Flash effective dose based on the planning parameters and the patient's planned CT scan. Since conformal Flash planning generally uses forward optimization, there is no reverse optimization function; 3) A compensator-modulated Flash planning module includes three sub-modules: parameter input, Flash effective dose calculation, and compensator-modulated Flash plan reverse optimization. The parameter input sub-module is mainly used to input parameters such as gantry angle, compensator material, and compensator initial thickness. The Flash effective dose calculation sub-module calculates the Flash effective dose based on the planning parameters and the patient's planned CT scan. The Flash plan reverse optimization function of the compensator intensity modulation automatically calculates and generates the optimal Flash plan parameters based on the set plan parameters and the calculated effective Flash dose.

[0074] For the three obtained plans, this planning system can transmit them to other systems in the standard DicomRT format via the planning parameter output module. Additionally, since the Flash plan for compensator intensity modulation requires compensator fabrication, this planning system includes a compensator parameter output module that can output the compensator's thickness distribution information.

[0075] This system allows for the design of intensity-modulated X-ray flash radiotherapy plans. It also allows for the free selection of conventional X-ray dose rate plans or MLC-conformal X-ray flash plans to meet various clinical needs.

[0076] In this embodiment, for the calculation model of effective dose distribution of X-ray flash with compensator intensity modulation, the dose distribution calculation model of the existing X-ray radiotherapy planning system does not consider the flash protection effect. Therefore, in this embodiment, it is necessary to combine the traditional dose distribution calculation model with the flash effect model to construct the effective dose distribution calculation model of flash.

[0077] The instantaneous intensity distribution of the beam after passing through the compensator can be calculated using the following formula:

[0078]

[0079] Where i represents the field number and t represents the treatment time. m i (t) represents the instantaneous machine dose rate as a function of time (in ticks per minute), S i This represents the geometric parameters of the shooting field, such as shape and size. and This represents the thickness distribution and density information of the compensator. F is a function used by the dose engine of a conventional X-ray radiotherapy planning system to calculate the intensity distribution. S (t) represents the instantaneous intensity distribution generated by the Flash accelerator head over time. Based on (1), the time-varying physical dose distribution within the patient's body can be obtained:

[0080]

[0081] Here I ct G represents the planned CT image, where D is a function used by the dose engine of a conventional X-ray radiotherapy planning system to calculate the physical dose distribution within the patient. i This indicates the angle of the shooting field. According to the work of MacKay et al. (MacKay, 2021), D... phy (t) can be converted into the Flash effective dose D using the following formula. FE (t):

[0082] D FE =∫M·dD phy (3)

[0083] For the X-ray flash planning optimization model with compensator intensity modulation, since the flash effect is mainly reflected in the protection of organs at risk, the dose target for the tumor target area is still calculated using physical dose to reduce the computational load; while for the dose constraint conditions of organs at risk, the calculated D is used. FE Perform the calculation.

[0084] In this embodiment, combining the expected clinical goals of clinical target coverage and organ at risk protection, the objective function of the planning optimization model can be expressed as:

[0085] f = ∑ i w T, iObj i (D phy )+∑ j w o,j Con j (D FE )+N (4)

[0086]

[0087] Where f is the overall objective function to be optimized.i with w T,i Let represent the dose objective function and corresponding weights for the i-th tumor target region, respectively. N represents the total number of radiation fields. This term is mainly because when a radiation field ends, the flash effect is interrupted. If a new radiation field generates the flash effect again, the cumulative dose needs to be recalculated and made to exceed the threshold. Therefore, the more radiation fields there are, the weaker the flash protection effect becomes. The Res(P) function is the constraint function for the parameters to be optimized, where P represents the parameters to be optimized. In this embodiment, P can be various parameters such as the compensated instantaneous intensity distribution and the compensator thickness. This refers to the strictly controlled dose limits that must not be exceeded to ensure treatment safety. (T) forced Then it is the corresponding threshold.

[0088] In one specific embodiment, if a Flash effective dose calculation model that depends only on dose rate is used, the dose correction factor matrix can be expressed as follows:

[0089]

[0090] Where d is a 3×1 vector representing the spatial coordinates of a voxel. R min This represents the minimum dose rate required to trigger the Flash protective effect. p is a constant less than 0 and greater than 1. It should be noted that the dose correction factor matrix is ​​a four-dimensional matrix. This is primarily because the dose at different voxel locations within the patient's body changes continuously over time. This means that the dose rate at different locations and at different times may differ. Therefore, the corresponding dose correction factor matrix needs to include three spatial dimensions and one temporal dimension to achieve accurate calculation of the effective Flash dose within the patient's body.

[0091] Figure 3 This demonstrates the relationship between the effective dose and physical dose in flash radiotherapy, which depends on the dose rate threshold. It can be seen that in traditional X-ray radiotherapy, the effective dose and physical dose have a 1:1 relationship. However, in X-ray flash radiotherapy, as the cumulative physical dose increases, the rate of increase in effective dose is less than 1. This means that X-ray flash radiotherapy can provide a better protective effect on normal tissues and organs.

[0092] In another specific embodiment, if a Flash effective dose calculation model that depends on dose and dose rate thresholds is used, the dose correction factor matrix can be expressed as follows:

[0093]

[0094] Where d and R min The definition is consistent with that in (4). D minThis represents the minimum cumulative dose required to trigger the Flash protection effect. p is a constant less than 0 and greater than 1. It can be seen that, unlike (4), in (5), the Flash protection effect requires the dose rate to be greater than R simultaneously. min And the cumulative dose is greater than D min If either of these two conditions is not met, the Flash protection effect will be reduced.

[0095] Figure 4 This diagram illustrates the relationship between physical dose and effective dose in an X-ray Flash therapy plan with three fields. As can be seen, for the first field in X-ray Flash radiotherapy, when the cumulative dose is less than a threshold, the effective dose equals the physical dose, consistent with conventional X-ray radiotherapy. However, when the cumulative dose exceeds the threshold, the Flash protection effect occurs, and the rate of increase in effective dose significantly decreases. After the first field ends and the process switches to the second field, the cumulative dose needs to be recalculated, so the rate of increase in effective dose relative to physical dose returns to 1. When the cumulative physical dose exceeds the threshold, the rate of increase in effective dose decreases again. Therefore, we can see that the relationship between physical dose and effective dose becomes more complex as the number of fields increases. A clear understanding of the relationship between dose distribution changes within the patient and each field is necessary to obtain an accurate effective dose distribution.

[0096] In another specific embodiment, a traditional X-ray intensity-modulated radiography (IMRT) program optimization framework can be used, which involves first optimizing the intensity distribution and then solving for the executable program parameters based on the obtained intensity distribution. In this approach, the objective function for optimization can be expressed as:

[0097] f = Σ i w T,i Obj i (D phy (F c (t),G i ))+Σ j w o,j Con j (D FE (F c (t),G i ))+N (7)

[0098]

[0099] As can be seen, f is represented as the corrected field intensity matrix F c (t) is a function of the number of shooting fields N. c The vectorization corresponding to the nth column of (t) F_d min F_d represents the minimum instantaneous field strength required to produce a flash protection effect.max This represents the maximum instantaneous field intensity achievable by the accelerator after compensation. It should be noted that the number of fields is included in the optimization objective function primarily because, for the calculation of the effective flash dose, which depends on the dose and dose rate threshold, a larger number of fields results in a closer approximation between the effective flash dose and the physical dose, thus weakening the flash protection effect.

[0100] Using (6), the model can generate the compensated instantaneous intensity distribution matrix of the shot and the number of shot fields:

[0101]

[0102] Once the target intensity distribution is obtained, we can solve for the compensator thickness distribution using the classical X-ray attenuation equation. The objective function is shown below:

[0103]

[0104] in, F represents the intensity distribution of the target in the nth firing field. open This represents the intensity distribution of the accelerator's open field. This represents the compensator thickness distribution in the nth field. |.|2 represents the operator for calculating the L2 norm. μ0 is the linear attenuation coefficient corresponding to the compensator material. c1, c2, and c3 are hyperparameters, whose specific values ​​will be updated during iterative optimization. r represents the off-axis distance of the beam, and S represents the size of the accelerator nose field. Here... c2·r and c3·S are used to correct the effects of beam hardening, beam divergence, and X-ray scattering on intensity distribution, respectively.

[0105] Using (10), the thickness distribution of the compensator, the number of machine jumps, and the size of the open field can be obtained:

[0106]

[0107] In this embodiment, the compensator parameters can also be directly output. In this case, the objective function of the optimization model can be expressed as:

[0108] f = ∑ j u i Obj i (D phy (C,Ma(t)))+∑ j v j Con j (D FE (C,Ma(t)))+N (11)

[0109]

[0110] As can be seen, f is represented as a function of the compensator parameter matrix C, the accelerator parameters Ma(t), and the number of fields N. Ma(t) consists of the instantaneous machine dose rate m(t) and the field size S(t). C consists of the vectorized compensator thickness distribution matrix for all fields. min With m max S represents the minimum machine dose rate required to produce the Flash effect and the maximum machine dose rate achievable by the accelerator, respectively. min With S max These represent the minimum and maximum field sizes, respectively. Thickness max This represents the maximum compensator thickness allowed to produce the flash protection effect. The optimal compensator and accelerator parameters can be obtained by solving for the minimum value of f.

[0111]

[0112] In summary, this invention proposes a compensator-modulated intensity-modulated (IMIM) X-ray flash radiotherapy method and system, providing the technical conditions for realizing IMIM and its clinical application. Compensator-modulated X-ray flash radiotherapy not only encompasses current research hotspots (flash radiotherapy) but also includes previously unexplored areas within flash radiotherapy. The provided technical conditions not only offer a comprehensive and flexible framework and basic methods for IMIM technology but also describe specific implementation details, such as calculating the effective dose for different flash effect models and optimizing the compensator-modulated X-ray flash plan using stepwise or synchronous methods. The method and system provided by this invention fill a gap in X-ray flash radiotherapy technology, which is of great significance for the translational application of flash radiotherapy technology and improving cancer treatment levels.

[0113] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0114] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0115] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0116] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0117] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. An intensity modulated X-ray Flash radiotherapy planning system, characterized by, include: The patient data management module is used to obtain basic patient information, patient imaging data, and patient radiotherapy plan data; The region of interest (ROI) determination module is used to determine the ROI for radiotherapy. The Flash planning design module for the compensator intensity modulation is used to calculate the effective Flash dose based on the planning parameters and the patient's planned CT scan, and to calculate and generate the optimal Flash planning parameters based on the set planning parameters and the calculated effective Flash dose. The calculation of the effective Flash dose based on the planning parameters and the patient's planned CT scan includes: Beam intensity distribution after compensator is: ； where i denotes the index of the field, t denotes the treatment time, denotes the time-varying instantaneous machine dose rate, denotes the field geometry parameters, and represents the compensator's thickness distribution and density information; F is a function that calculates the fluence distribution using the dose engine of a conventional X-ray radiotherapy planning system; Therefore, the distribution of physical doses in the patient's body over time is as follows: ； Indicates the planned CT images, A function for calculating the physical dose distribution in a patient's body using the dose engine of a conventional X-ray radiotherapy planning system; This indicates the corner of the shooting field; Convert to Flash effective dose using the following formula : .

2. The X-ray Flash radiotherapy planning system with compensator intensity modulation according to claim 1, characterized in that, Combining the expected clinical goals of clinical target coverage and organ at risk protection, the objective function of the planned optimization model is expressed as: ； ； Where f is the overall objective function to be optimized. and Let represent the dose objective function and corresponding weights for the i-th tumor target region, respectively, and N represent the total number of radiation fields. The function is the constraint function for the parameters to be optimized, and P represents the parameters to be optimized. This refers to the strict dosage constraints that must not be exceeded to ensure treatment safety and prevent damage to organs at risk. Then it is the corresponding threshold.

3. The X-ray Flash radiotherapy planning system with compensator intensity modulation according to claim 1, characterized in that, If a Flash effective dose calculation model that depends on dose and dose rate thresholds is used, the dose correction factor matrix is ​​expressed as: ； in, This indicates the minimum cumulative dose required to trigger the Flash protection effect.

4. A method for planning X-ray flash radiotherapy with intensity modulation using a compensator, characterized in that, include: Obtain the patient's basic information, patient imaging data, and patient radiotherapy plan data; Identify the region of interest for radiotherapy; The effective Flash dose is calculated based on the planning parameters and the patient's planned CT scan. The optimal Flash planning parameters are then generated based on the calculated effective Flash dose and the set planning parameters. The calculation of the effective Flash dose based on the planning parameters and the patient's planned CT scan includes: Instantaneous intensity distribution of the beam after passing through the compensator for: ； Where i represents the field number and t represents the healing time. Indicates the instantaneous machine dose rate as it changes over time. Indicates the geometric parameters of the shooting field. and The thickness distribution and density information of the compensator are represented; F is a function that calculates the intensity distribution using the dose engine of a conventional X-ray radiotherapy planning system. Therefore, the distribution of physical doses in the patient's body over time is as follows: ； Indicates the planned CT images, A function for calculating the physical dose distribution in a patient's body using the dose engine of a conventional X-ray radiotherapy planning system; This indicates the corner of the shooting field; Convert to Flash effective dose using the following formula : .

5. The X-ray Flash radiotherapy planning method with compensator intensity modulation according to claim 4, characterized in that, Combining the expected clinical goals of clinical target coverage and organ at risk protection, the objective function of the planned optimization model is expressed as: ； ； Where f is the overall objective function to be optimized. and Let represent the dose objective function and corresponding weights for the i-th tumor target region, respectively, and N represent the total number of radiation fields. The function is the constraint function for the parameters to be optimized, and P represents the parameters to be optimized. This refers to the strict dosage constraints that must not be exceeded to ensure treatment safety and prevent damage to organs at risk. Then it is the corresponding threshold.

6. The X-ray Flash radiotherapy planning method with compensator intensity modulation according to claim 4, characterized in that, If a Flash effective dose calculation model that depends on dose and dose rate thresholds is used, the dose correction factor matrix is ​​expressed as: ； in, This indicates the minimum cumulative dose required to trigger the Flash protection effect.

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