Treatment head angle distribution method and device for multi-beam radiotherapy system

Abstract

The invention provides a treatment head angle distribution method and system for a multi-beam radiotherapy system, and belongs to the technical field of medical equipment, and the method comprises the steps: obtaining ray beam angle data used for the treatment of a patient; inputting the obtained ray beam angle data into an angle distribution optimization model for solving to obtain a treatment head angle distribution result; wherein the angle of each treatment head is represented by a single variable, the allowable change range of the angle is defined as a constraint condition of the variable, the consistency between the treatment angle provided by a treatment machine and the angle required by treatment is defined as an optimization objective function, and an angle distribution optimization model is established; and adjusting the treatment head based on the obtained angle distribution result of the treatment head to enable the treatment head to be at an angle required by treatment. According to the invention, the relative angle relation between the ray beam directions is determined, so that the ray beam angle of the flash radiotherapy machine meets the radiotherapy requirements of tumors at different parts of different patients, and the irradiation angle required by fixed field intensity modulated radiation therapy of all patients is accurately realized.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment, and in particular to a treatment head angle distribution method and device for a multi-beam radiotherapy system. Background Art

[0002] Radiotherapy is a treatment method that uses radiation beams such as X-rays and electron beams to kill tumors. The radiation beams are generated by the radiotherapy system and led out through the treatment head. Usually, a treatment system is equipped with only one treatment head, which can only generate a single-directional radiation beam to treat tumors. For superficial tumors, a single-directional radiation beam can be irradiated vertically. However, most tumors are located in the patient's body, and radiation beams in multiple directions are required to focus and irradiate in order to increase the dose difference between the tumor target area and the surrounding normal tissues. Radiation beams in different directions are achieved in sequence by rotating the treatment head around the patient's body.

[0003] One of the current research and development directions of the treatment system is to integrate multiple treatment heads into one treatment system to form a multi-beam treatment system. The advantage of such integration is that when multiple beams of radiation are required for focused irradiation, the treatment head can be rotated less or even not rotated at all. The advantage of such integration is particularly important for flash therapy. The reason is that flash therapy requires all radiation beams to be irradiated within sub-seconds. Obviously, the treatment head cannot rotate so fast, but multiple treatment heads can be kept from rotating. Electronic control can be used to achieve simultaneous irradiation of multiple treatment heads, or rapid irradiation in sequence. The distribution of multiple treatment heads in the space of the multi-beam radiotherapy system can adopt different designs, such as whether the radiation beams drawn by these treatment heads are coplanar, whether they are distributed at equal angles, whether the angles relative to different treatment heads can be changed, etc. A flash radiotherapy machine design is to arrange several treatment heads on a ring frame (the symbol n is used below to represent the number of treatment heads). The n treatment heads can rotate as a whole with the ring frame. Each treatment head emits a radiation beam, so that the treatment machine rotates into place once, and the arrangement of radiation beams that irradiate at n angles simultaneously or nearly simultaneously can be achieved. The n beams are coplanar and their relative angles are fixed, but the n angles can be rotated as a whole within the coplanar range. In other words, when the n angles are rotated and changed, as long as any one of them is known, the remaining (n-1) angles can be determined based on the relative angle relationship.

[0004] Radiotherapy requires multiple carefully selected beam angles, and beam angle selection is an important step in planning. The selected beam angles must follow certain principles and be suitable for individualized treatment needs, but in general, the same or similar treatment angles are used for the same type of tumor. In order for the flash radiotherapy machine's beam angles to meet the radiotherapy needs of different patients with different tumor locations, the relative angle relationship between the beam directions (i.e., beam angle distribution) is very important. The optimal relative angle relationship should enable the radiotherapy machine to achieve the required irradiation angle distribution for all patients as accurately as possible in one or more irradiations. Summary of the invention

[0005] The object of the present invention is to provide a method and device for angle distribution of a treatment head for a multi-beam radiotherapy system, so as to solve at least one technical problem existing in the above-mentioned background technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a method for distributing the angle of a treatment head for a multi-beam radiotherapy system, comprising:

[0008] Establish a head angle optimization model, that is, use a single variable to represent the angle of each treatment head, define the restricted conditions of the treatment head angle distribution as the constraint conditions of the variable, and define the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function, thus forming an angle distribution optimization model;

[0009] Obtain representative beam angle distribution data for a group of patients treated;

[0010] The obtained ray beam angle distribution data, the number of treatment heads to be arranged on the treatment frame, and the restricted conditions of the angle distribution of the treatment heads are input into the angle distribution optimization model for solving, so as to obtain the angle distribution result of the treatment heads;

[0011] Based on the obtained treatment head angle distribution results, all treatment head angles are adjusted as a whole for specific patients so that all treatment heads are as close as possible to the angle required for treatment.

[0012] Optionally, establish an angle distribution optimization model, including:

[0013] Assume there are n treatment heads, with n angles A1 to A n (0≤A i ≤2π,1≤i≤n), with the overall rotation, A1~A n The specific values ​​will change, but the relationship between them satisfies:

[0014] A i+1 =A1+αi i=1,2,…,n-1

[0015] α1~α n-1 That is, it is the optimization variable, and its value needs to be determined through optimization.

[0016] Assume that the constraints on the angle distribution of the treatment head are:

[0017]

[0018] In order to determine the optimal relative angle relationship α1~α n-1 , a batch of irradiation angles of clinically used fixed-field intensity-modulated plans are used as samples of the radiotherapy patient population. The optimization goal is to make the set of irradiation angles that can be achieved by the flash therapy machine consistent with the set of beam angles actually used by the patient, that is, the objective function value is the difference between the irradiation angles achieved by the flash therapy machine and the angles required for fixed-field intensity-modulated therapy.

[0019] Optionally, assume that the number of beams used in the fixed field intensity modulation plan is M, and the beam angles are B1 to B M ; When M≤n, directly select M angles A1~A from n angles M , determine the overall rotation angle β of the frame; the value of β should minimize the following formula:

[0020]

[0021] For this minimization problem, the value of β should be (B i -A i )(1≤i≤M). In this way, the rack rotation angle β can be calculated for each angle selection scheme, thereby calculating the difference between the irradiation angle achieved by the flash therapy machine and the required irradiation angle. Compare the differences corresponding to the various angle selection schemes, and select the scheme with the smallest difference.

[0022] Optionally, when M≥n+1, the M radiation beams are divided into C groups, with the number of radiation beams in each group not exceeding n. The beam angles and the overall rotation angle β selected when irradiating each group of radiation beams are determined separately, and the difference between the achieved angle and the angle required for treatment is calculated. The differences corresponding to the various radiation beam grouping schemes are compared, and the scheme with the smallest difference is selected.

[0023] Optionally, for a given relative angle relationship α1 to α n-1 , use the enumeration method to calculate the minimum difference between the irradiation angle that the treatment head can achieve and the irradiation angle required by a set of fixed field intensity modulation plans. Then the optimization problem is: variables α1~α n-1 For which value the ray beam angle difference is minimal:

[0024]

[0025] Optionally, evaluate the consistency ΔG between the treatment angle provided by the treatment machine and the angle required for treatment:

[0026] Where C represents the angle required to achieve treatment in C times, M i A represents the number of treatment angles included in the i-th treatment; ij represents the angle of the treatment head used in the i-th treatment, β i represents the overall rotation angle of the gantry for the i-th treatment, B ij represents the irradiation angle that needs to be achieved in the i-th treatment.

[0027] In a second aspect, the present invention provides a treatment head angle distribution device for a multi-beam radiotherapy system, comprising:

[0028] Modeling module, i.e., using a single variable to represent the angle of each treatment head, defining the restricted conditions of the angle distribution of the treatment head as the constraint conditions of the variable, defining the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function, and establishing an angle distribution optimization model;

[0029] An acquisition module, used for acquiring the angle data of the ray beam used for treating the patient;

[0030] A solution module is used to solve the acquired ray beam angle distribution data and the number of treatment heads to be arranged on the input treatment frame, as well as the restricted condition angle distribution optimization model of the treatment head angle distribution, to obtain the treatment head angle distribution result;

[0031] The adjustment module is used to adjust the treatment head based on the obtained treatment head angle distribution result so that the treatment head is at the angle required for treatment.

[0032] In a third aspect, the present invention provides a multi-beam radiotherapy system, comprising the treatment head angle distribution device for the multi-beam radiotherapy system as described above, wherein the relative position relationship between the treatment heads of the multi-beam radiotherapy system is fixed, and the spacing between adjacent treatment heads is not all the same, that is, a non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment heads of the multi-beam therapy system is adjusted using the method described above.

[0033] In a fourth aspect, the present invention provides a flash beam radiotherapy machine, comprising the treatment head angle distribution device for a multi-beam radiotherapy system as described above, wherein multiple treatment heads of the flash beam radiotherapy machine are distributed on an annular frame, and the multiple treatment heads can rotate as a whole with the annular frame, and the spacing between adjacent treatment heads is fixed and unchanged, and these spacings are not all the same, that is, non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment head of the flash beam radiotherapy machine is adjusted using the method described above.

[0034] In a fifth aspect, the present invention provides a non-transitory computer-readable storage medium, which is used to store computer instructions. When the computer instructions are executed by a processor, the treatment head angle distribution method for a multi-beam radiotherapy system as described above is implemented.

[0035] In a sixth aspect, the present invention provides a computer program product, comprising a computer program, wherein when the computer program is executed on one or more processors, the computer program is used to implement the above-mentioned treatment head angle distribution method for a multi-beam radiotherapy system.

[0036] In a seventh aspect, the present invention provides an electronic device, comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes instructions for implementing the treatment head angle distribution method for a multi-beam radiotherapy system as described above.

[0037] The beneficial effects of the present invention are as follows: the relative angle relationship between the directions of the radiation beams is determined, so that the radiation beam angle of the flash radiotherapy machine can meet the radiotherapy needs of tumors in different parts of different patients, and can accurately achieve the irradiation angle required for fixed-field intensity-modulated radiotherapy for all patients.

[0038] Additional advantages of the present invention will be more clearly given in the following description or learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0040] Figure 1 4 is a structural diagram of a multi-beam radiotherapy system according to an embodiment of the present invention.

[0041] Figure 2 This is a flow chart of the treatment head angle distribution method according to an embodiment of the present invention.

[0042] Figure 3 This is the treatment head angle used in the treatment of rectal cancer determined according to the method of this embodiment described in the embodiment of the present invention.

[0043] Figure 4The breast plan described in the embodiment of the present invention only retains the tangent field angle and removes the ray beam number distribution diagram after the intensity modulated field processing adjacent to the tangent field. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below by the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0045] It should be understood by those skilled in the art that unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.

[0046] It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have a meaning consistent with that in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless as defined herein.

[0047] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the 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.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0049] To facilitate understanding of the present invention, the present invention is further explained below with reference to specific embodiments in conjunction with the accompanying drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0050] Those skilled in the art should understand that the drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily necessary for implementing the present invention.

[0051] Example 1

[0052] In this embodiment 1, firstly, a treatment head angle distribution device for a multi-beam radiotherapy system is provided, comprising: a modeling module, which uses a single variable to represent the angle of each treatment treatment head, defines the restricted conditions of the treatment head angle distribution as the constraint conditions of the variable, defines the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function, and establishes an angle distribution optimization model; an acquisition module, which is used to acquire the angle data of the radiation beam used for patient treatment; a solution module, which is used to input the acquired radiation beam angle distribution data and the number of treatment heads to be arranged on the treatment machine frame, as well as the restricted conditions of the treatment head angle distribution into the angle distribution optimization model for solution to obtain the treatment head angle distribution result; and an adjustment module, which is used to adjust the treatment head based on the obtained treatment head angle distribution result so that the treatment head is at the angle required for treatment.

[0053] In this embodiment 1, the above-mentioned device is used to implement a method for distributing the angle of a treatment head for a multi-beam radiotherapy system, including: using an acquisition module to obtain the angle data of the radiation beam used for patient treatment; using a solution module to input the obtained angle data of the radiation beam into an angle distribution optimization model for solution to obtain a treatment head angle distribution result; wherein a single variable is used to represent the angle of each treatment treatment head, the allowable range of variation of the angle is defined as a constraint condition of the variable, the consistency between the treatment angle provided by the treatment machine and the angle required for treatment is defined as an optimization objective function, and an angle distribution optimization model is established; and using an adjustment module to adjust the treatment head based on the obtained treatment head angle distribution result so that the treatment head is at the angle required for treatment.

[0054] Among them, the angle distribution optimization model is established, including:

[0055] Assume there are n treatment heads, with n angles A1 to A n (0≤A i ≤2π,1≤i≤n), with the overall rotation, A1~A n The specific values ​​will change, but the relationship between them satisfies:

[0056] A i+1 =A1+α i i=1,2,…,n-1

[0057] α1~α n-1 That is, it is the optimization variable, and its value needs to be determined through optimization.

[0058] Assume that the constraints on the angle distribution of the treatment head are:

[0059]

[0060] In order to determine the optimal relative angle relationship α1~αn-1 , a batch of irradiation angles of clinically used fixed-field intensity-modulated plans are used as samples of the radiotherapy patient population. The optimization goal is to make the set of irradiation angles that can be achieved by the flash therapy machine consistent with the set of beam angles actually used by the patient, that is, the objective function value is the difference between the irradiation angles achieved by the flash therapy machine and the angles required for fixed-field intensity-modulated therapy.

[0061] Assume that the number of beams used in the fixed field intensity modulation plan is M, and the beam angles are B1 to B M ; When M≤n, directly select M angles A1~A from n angles M , determine the overall rotation angle β of the frame; the value of β should minimize the following formula:

[0062]

[0063] For this minimization problem, the value of β should be (B i -A i )(1≤i≤M). In this way, the rack rotation angle β can be calculated for each angle selection scheme, thereby calculating the difference between the irradiation angle achieved by the flash therapy machine and the required irradiation angle. Compare the differences corresponding to the various angle selection schemes, and select the scheme with the smallest difference.

[0064] When M≥n+1, the M radiation beams are divided into C groups, with the number of radiation beams in each group not exceeding n. The beam angle and the overall rotation angle β selected when irradiating each group of radiation beams are determined separately, and the difference between the achieved angle and the angle required for treatment is calculated. The differences corresponding to the various radiation beam grouping schemes are compared, and the scheme with the smallest difference is selected.

[0065] For a given relative angle relationship α1~α n-1 , use the enumeration method to calculate the minimum difference between the irradiation angle that the treatment head can achieve and the irradiation angle required by a set of fixed field intensity modulation plans. Then the optimization problem is: variables α1~α n-1 For which value the ray beam angle difference is minimal:

[0066] Optionally, evaluate the consistency ΔG between the treatment angle provided by the treatment machine and the angle required for treatment:

[0067] Where C represents the angle required to achieve treatment in C times, M i A represents the number of treatment angles included in the i-th treatment; ij represents the angle of the treatment head used in the i-th treatment, β i represents the overall rotation angle of the gantry for the i-th treatment, B ij represents the irradiation angle that needs to be achieved in the i-th treatment.

[0068] Example 2

[0069] In order to improve Figure 1 The angle distribution of the treatment head of the multi-beam radiation system shown in FIG. 1 is also used to establish the angle distribution of the treatment head suitable for the flash radiotherapy machine (Flash), such as Figure 2 As shown, in this embodiment, a method for optimizing and determining angle distribution is established. The goal is to provide a treatment angle that is consistent with the traditional treatment angle. The specific steps include establishing a model, a database, and optimizing the solution.

[0070] Establishing a mathematical model for optimizing and determining angle distribution includes:

[0071] Assume that the flash therapy machine has n treatment heads, and the n angles are A1 to A n (0≤A i ≤2π,1≤i≤n), as the flash therapy machine rotates as a whole, A1~A n The specific values ​​will change, but the relationship between them satisfies:

[0072] A i+1 =A1+α i i=1,2,…,n-1

[0073] α1~α n-1 That is, it is the optimization variable, and its value needs to be determined through optimization.

[0074] Some design considerations of the treatment machine will impose some restrictions on the angle distribution. Assume that the constraints on the angle distribution are:

[0075] In order to determine the optimal relative angle relationship α1~α n-1 , a batch of irradiation angles of clinically used fixed-field intensity-modulated plans are used as samples of the radiotherapy patient population. The optimization goal is to make the set of irradiation angles that can be achieved by the flash therapy machine and the set of beam angles actually used by the patient as consistent as possible, that is, the objective function value is the difference between the irradiation angles achieved by the flash therapy machine and the angles required for fixed-field intensity-modulated therapy.

[0076] First, consider how to achieve the required treatment beam angle for a treatment plan. Suppose the number of beams used in a fixed field intensity modulation plan is M, and the beam angles are B1 to B2. M When M≤n, directly select M angles A1~A from the n angles of the flash therapy machine M , depending on the specific value of M, there are The first selection method is to determine the overall rotation angle β of the rack after selecting the harness angle to be used. The value of β should minimize the following formula:

[0077]

[0078] For this minimization problem, the value of β should be (B i -A i )(1≤i≤M). In this way, the rack rotation angle β can be calculated for each angle selection scheme, thereby calculating the difference between the irradiation angle achieved by the flash therapy machine and the required irradiation angle. Compare the differences corresponding to the various angle selection schemes, and select the scheme with the smallest difference.

[0079] When M≥n+1, the M radiation beams are divided into C groups, and the number of radiation beams in each group does not exceed n. All grouping situations can be listed according to the theory of permutations and combinations. After the radiation beam grouping is determined, according to the above-mentioned situation of M≤5, the flash therapy machine beam angle and the overall rotation angle β of the flash therapy machine are determined when irradiating each group of radiation beams, so as to calculate the difference between the angle achieved by the flash therapy machine and the angle required for treatment. Compare the differences corresponding to each radiation beam grouping scheme, and select the scheme with the smallest difference.

[0080] In summary, for a given relative angle relationship α1~α n-1 , we can use the enumeration method to calculate the minimum difference between the irradiation angle that the flash therapy machine can achieve and the irradiation angle required by a set of fixed field intensity modulation plans. So the optimization problem is summarized as variables α1~α n-1 When the value is taken, the difference in the ray beam angle is the smallest. Preliminary estimation shows that the amount of calculation required for the enumeration method to calculate the objective function value should be within an acceptable range. If there is a calculation method that is more efficient than enumeration, the optimization speed can be accelerated.

[0081]

[0082] In this embodiment, the ray beam angle database used for treatment is: In order to optimize the relative angle relationship α1~α n-1 , a set of clinically used fixed-field intensity-modulated treatment plans is required, and the beam angles used in these plans are input into the optimization program as the basis for calculating the objective function value. Some key points need to be noted when establishing a database. First, the distribution of different diseases in the database should reflect the distribution of actual cases in the clinic as much as possible, and exclude the influence of treatment technologies such as VMAT and Tomo on fixed-field intensity-modulated technology. Secondly, the influence of some special treatment technologies such as breast hybrid intensity-modulated technology on the database should be excluded.

[0083] In this embodiment, the optimization algorithm used is: a variety of mathematical optimization algorithms can be used to solve the problems in the mathematical model to obtain the angle distribution of the multi-beam radiation system treatment head. The optimization algorithms that can be used include a variety of heuristic algorithms, such as simulated annealing algorithms and genetic algorithms.

[0084] Example 3

[0085] In this embodiment, a treatment head angle distribution design for a multi-beam radiotherapy system is provided, wherein the relative positional relationship between the treatment heads is fixed, but the spacings between adjacent treatment heads are not all the same, that is, a non-equidistant treatment head angle distribution is adopted. For a treatment head angle distribution design for a flash therapy (FlashTherapy) machine, it is characterized in that a plurality of treatment heads are distributed on a circular frame, these treatment heads can rotate with the circular frame as a whole, the spacings between adjacent treatment heads are fixed, and these spacings are not all the same, that is, a non-equidistant treatment head angle distribution is adopted.

[0086] The formula for evaluating the consistency between the treatment angle provided by the treatment machine and the angle required for treatment is:

[0087]

[0088] Where C represents the angle required to achieve treatment in C times, M i A represents the number of treatment angles included in the i-th treatment. ij represents the angle of the treatment head used in the i-th treatment, β i represents the overall rotation angle of the gantry for the i-th treatment, B ij represents the irradiation angle that needs to be achieved in the i-th treatment.

[0089] The process of optimizing and determining the angle distribution of multiple treatment heads includes: using the treatment data stored in the treatment data system as a reference, formulating evaluation criteria for evaluating the angle distribution scheme of the treatment heads of the treatment system, establishing an optimization model, and optimizing and determining the best angle distribution using mathematical optimization methods.

[0090] A design system for optimizing and determining the angle distribution of multiple treatment heads includes: a data input unit for inputting the angle data of the radiation beam used for treating a large sample of patients collected from a treatment data system; a problem description unit for representing the angle of each treatment head with a single variable, defining the allowable range of variation of the angle as a constraint of the variable, defining the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as an objective function of the optimization problem, and establishing a mathematical model to describe the optimization problem; a problem solving unit for solving the optimization problem with an optimization mathematical algorithm such as a simulated annealing algorithm and a genetic algorithm; and a data output unit for outputting the optimized angle distribution of the treatment heads to the design system of the multi-beam treatment machine and verifying the rationality of the angle distribution.

[0091] The method for optimizing and determining the angle distribution of multiple treatment heads comprises the following steps: a problem description step, using a single variable to represent the angle of each treatment head, defining the allowable range of angle variation as a constraint condition of the variable, defining the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the objective function of the optimization problem, and establishing a mathematical model to describe the optimization problem; a problem solving step, using a simulated annealing algorithm, a genetic algorithm or other optimization mathematical algorithm to solve the optimization problem; and a data output step, for outputting the optimized angle distribution of the treatment head to the design system of the multi-beam treatment machine and verifying the rationality of the angle distribution.

[0092] Example 4

[0093] In this embodiment 4, a method for adjusting the treatment head of a radiotherapy system is provided, and the method steps include: a problem description step, using a single variable to represent the angle of each treatment treatment head, defining the allowable variation range of the angle as a constraint condition of the variable, defining the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the objective function of the optimization problem, and establishing a mathematical model that describes the optimization problem; a problem solving step, using an optimization mathematical algorithm such as a simulated annealing algorithm and a genetic algorithm to solve the optimization problem; a data output step, for outputting the optimized treatment head angle distribution to the design system of the multi-beam treatment machine, and verifying the rationality of the angle distribution.

[0094] Mathematical model for angle selection problem: Assume that the flash therapy machine has 5 treatment heads and can irradiate 5 irradiation beams at a time, that is, n = 5. The 5 angles are A1~A5 (0≤A i ≤2π,1≤i≤5), as the flash therapy machine rotates as a whole, the specific values ​​of A1~A5 will change, but the relationship between them satisfies:

[0095] A i+1 =A1+α i i=1,2,3,4

[0096] α1~α4 are optimization variables, and their values ​​need to be determined through optimization.

[0097] Considering that the imaging system needs to be installed on the rack, there are two constraints on the beam angle: one is that the imaging system occupies two angles with an interval of 180°, and the interval between the adjacent beam angles is at least 25° to meet the installation space requirements. The second is that the angle of the imaging system is perpendicular to one of the beam angles. To meet the above two constraints, let's assume that the angles occupied by the imaging system are 90° and 270°, the beam angle A1 is 0°, and the constraints on the distribution of the other four angles are:

[0098] 0≤A i ≤65 or 115≤A i ≤245 or 295≤A i≤360, i=2,3,4,5

[0099] In order to determine the optimal relative angle relationship α1~α4, a group of irradiation angles of fixed-field intensity-modulated plans used in clinical practice are used as samples of the radiotherapy patient population. The optimization goal is to make the set of irradiation angles that can be achieved by the flash therapy machine and the set of beam angles actually used by the patient as consistent as possible, that is, the objective function value is the difference between the irradiation angles achieved by the flash therapy machine and the angles required for fixed-field intensity-modulated therapy.

[0100] Assume that the number of beams used in the fixed field intensity modulation plan is M, and the beam angles are B1 to B M When M≤5, directly select M angles A1~A1 from the five angles of the flash therapy machine. M , depending on the specific value of M, there are The first selection method is to determine the overall rotation angle β of the frame after selecting the harness angle to be used.

[0101] The value of β should minimize the following formula:

[0102]

[0103] When 6≤M≤10, first divide the M beams into two groups. For example, when M is 6, the number of beams in the two groups can be 1 and 5, 2 and 4, or 3 and 3, for a total of Similarly, when M is equal to 7, there is grouping schemes; when M is equal to 8, there are grouping schemes; when M is equal to 9, there are grouping schemes; when M is equal to 10, there are After the beam grouping is determined, according to the above-mentioned situation of M≤5, the beam angle of the flash therapy machine and the overall rotation angle β of the flash therapy machine are determined when irradiating each group of beams, so as to calculate the difference between the angle achieved by the flash therapy machine and the angle required for treatment. Compare the differences corresponding to each beam grouping scheme, and select the scheme with the smallest difference.

[0104] In summary, for a given relative angle relationship α1~α4, the enumeration method can be used to calculate the minimum difference between the irradiation angle that can be achieved by the flash therapy machine and the irradiation angle required by a set of fixed field intensity modulation plans. Therefore, the optimization problem can be summarized as the value of variables α1~α4 when the difference in beam angle is the smallest. Preliminary estimates show that the amount of calculation required to calculate the objective function value by the enumeration method should be within an acceptable range. If there is a calculation method with higher efficiency than enumeration, the optimization speed can be accelerated.

[0105] For the beam angle data used in fixed-field intensity-modulated plans: all fixed-field intensity-modulated plans in the radiotherapy department within 1 to 2 years before the implementation of VMAT technology were selected, the beam angles of these plans were read and stored in the beam angle database.

[0106] The specific process of establishing the ray beam angle database is as follows:

[0107] The angle data of all treatment plans from January 2012 to January 2014 were read, and a total of 69,928 beams from 8,866 patients were read.

[0108] Since the Varian machine beam is often divided into two fields, a and b, and a few plans may use beams with the same angle, the repeated angles in the plan should be removed (that is, only one identical beam angle is retained).

[0109] Since most breast plans use a special planning design method (hybrid intensity-modulated plan), only the tangent field angle is retained for this plan, and the intensity-modulated field adjacent to the tangent field is removed. After processing, the distribution of the number of beams is as follows: Figure 4 As shown in Table 1.

[0110] Table 1

[0111]

[0112] The simulated annealing algorithm is used to program and solve the optimization problem. According to the results of the optimization program, the rack design angles are shown in Table 2.

[0113] Table 2

[0114] Serial number 1 2 3 4 5 Rack angle (°) 0 40.4 169.4 201.2 239.8

[0115] The objective function corresponding to the optimal solution is 38.9°, which means that the average difference between each planned angle is 38.9°.

[0116] In this embodiment, based on the optimized gantry angle, the implementation scheme is verified for several frequently appearing angle distributions in the ray beam angle database used in the treatment plan:

[0117] In the treatment plan with 5 beams, the most frequent angle distribution is 0, 45, 95, 265, 315, which appears 127 times in total. This angle distribution is generally used in the five-field intensity modulation plan for rectal cancer. For this angle distribution, the optimization program directly uses the 5 machine angles to rotate an angle β as a whole. The calculated β value is 95, and the objective function value f is calculated as:

[0118] f=|169.4+β-265|+|201.2+β-315|+|239.8+β-0|+|0+β-45|

[0119] +|41.4+β-95|=135

[0120] In the plan with 6 beams, the most frequent angle distribution is 0, 30, 80, 130, 160, 200, which appears 204 times in total. This angle distribution is generally used for intensity modulation plans for chest tumors. For this angle distribution, the optimization program gives a solution that is implemented in two times, and the machine angle and overall rotation angle β used are shown in Table 3 below.

[0121] Table 3

[0122]

[0123] The objective function value f is calculated as:

[0124] f=|0+β1-80|+|40.1+β1-130|+|0+β2-0|+|40.4+β2-30|

[0125] +|169.4+β2-160|+|201.2+β2-200|=30.3

[0126] In the plan with 7 beams, the most frequent angle distribution is 26, 78, 129, 180, 231, 283, 334, which appears 241 times in total. For this angle distribution, the optimization program gives a solution of implementing it in two times, and the machine angle and overall rotation angle β used are shown in Table 4 below.

[0127] Table 4

[0128]

[0129] The objective function value f is calculated as:

[0130] f=|201.2+β1-129|+|239.8+β1-180|+|0+β1-283|+|40.4+β1-334|+|0+β2-26|+|40.4+β2-78|+|201.2+β2-231|=31

[0131] In the plan with 9 beams, the most frequent angle distribution is 0, 40, 80, 120, 160, 200, 240, 280, 320, which appears 1748 times in total. It is not difficult to achieve this angle distribution using machine angle.

[0132] Example 5

[0133] In this embodiment 5, a multi-beam radiotherapy system is provided, comprising the treatment head angle distribution device as described in embodiment 1, wherein the relative position relationship between the treatment heads of the multi-beam radiotherapy system is fixed, and the spacing between adjacent treatment heads is not the same, that is, a non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment heads of the multi-beam radiotherapy system is adjusted using the treatment head angle distribution method for a multi-beam radiotherapy system as described in the above embodiment.

[0134] Example 6

[0135] In this embodiment 6, a flash beam radiotherapy machine includes a treatment head angle distribution device as described in embodiment 1, wherein multiple treatment heads of the flash beam radiotherapy machine are distributed on a circular ring frame, and the multiple treatment heads can rotate with the circular ring frame as a whole, and the spacing between adjacent treatment heads is fixed and unchanged, and these spacings are not all the same, that is, non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment head of the flash beam radiotherapy machine is adjusted using the treatment head angle distribution method for a multi-beam radiotherapy system as described in the above embodiment.

[0136] Example 7

[0137] This embodiment 7 provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the treatment head angle distribution method for a multi-beam radiotherapy system as described above is implemented. The method includes:

[0138] Obtaining data on the angle of the radiation beam used to treat the patient;

[0139] The acquired beam angle data is input into the angle distribution optimization model for solving, and the angle distribution result of the treatment head is obtained; wherein, a single variable is used to represent the angle of each treatment head, the allowable range of the angle is defined as the constraint condition of the variable, the consistency between the treatment angle provided by the treatment machine and the angle required for treatment is defined as the optimization objective function, and the angle distribution optimization model is established;

[0140] Based on the obtained treatment head angle distribution results, the treatment head is adjusted to place the treatment head at the angle required for treatment.

[0141] Example 8

[0142] Embodiment 8 provides a computer program product, including a computer program. When the computer program is executed on one or more processors, the computer program is used to implement the above-mentioned method for distributing the angles of a treatment head for a multi-beam radiotherapy system. The method includes:

[0143] Describe the model, i.e., use a single variable to represent the angle of each treatment head, define the restricted conditions of the angle distribution of the treatment head as the constraints of the variable, and define the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function;

[0144] Obtaining data on the angle of the radiation beam used to treat the patient;

[0145] The obtained ray beam angle distribution data, the number of treatment heads to be arranged on the treatment frame, and the restricted conditions of the angle distribution of the treatment heads are input into the angle distribution optimization model for solving, so as to obtain the angle distribution result of the treatment heads;

[0146] Based on the obtained treatment head angle distribution results, the treatment head is adjusted to place the treatment head at the angle required for treatment.

[0147] Example 9

[0148] Embodiment 9 provides an electronic device, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes instructions for implementing the above-mentioned method for distributing angles of a treatment head for a multi-beam radiotherapy system, the method comprising:

[0149] Describe the model, i.e., use a single variable to represent the angle of each treatment head, define the restricted conditions of the angle distribution of the treatment head as the constraints of the variable, and define the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function;

[0150] Obtaining data on the angle of the radiation beam used to treat the patient;

[0151] The obtained ray beam angle distribution data, the number of treatment heads to be arranged on the treatment frame, and the restricted conditions of the angle distribution of the treatment heads are input into the angle distribution optimization model for solving, so as to obtain the angle distribution result of the treatment heads;

[0152] Based on the obtained treatment head angle distribution results, the treatment head is adjusted to place the treatment head at the angle required for treatment.

[0153] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0154] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0155] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0156] These computer program instructions can also be loaded onto a computer or other programmable data processing device, and a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0157] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative work on the basis of the technical solution disclosed in the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for distributing the angle of a treatment head for a multi-beam radiotherapy system, characterized in that: include: A single variable is used to represent the angle of each treatment head, the restricted conditions of the angle distribution of the treatment head are defined as the constraint conditions of the variable, the consistency between the treatment angle provided by the treatment machine and the angle required for treatment is defined as the optimization objective function, and an angle distribution optimization model is established; Obtaining data on the angle of the radiation beam used to treat the patient; Solve the angle distribution optimization model of the acquired ray beam angle distribution data, the number of treatment heads to be arranged on the input treatment frame, and the restricted conditions of the angle distribution of the treatment heads to obtain the angle distribution result of the treatment heads; Based on the obtained treatment head angle distribution results, the treatment head is adjusted to place the treatment head at the angle required for treatment.

2. The method for distributing the angle of a treatment head for a multi-beam radiotherapy system according to claim 1, characterized in that: Establish an angle distribution optimization model, including: Assume there are n treatment heads, with n angles A1 to A n (0≤A i ≤2π,1≤i≤n), with the overall rotation, A1~A n The specific values ​​will change, but the relationship between them satisfies: A i+1 =A l +a i i=1, 2,..., n-1 α1~α n-1 That is, it is the optimization variable, and its value needs to be determined through optimization. Assume that the constraints on the angle distribution of the treatment head are: In order to determine the optimal relative angle relationship α1~α n-1 , a batch of irradiation angles of clinically used fixed-field intensity-modulated plans are used as samples of the radiotherapy patient population. The optimization goal is to make the set of irradiation angles that can be achieved by the flash therapy machine consistent with the set of beam angles actually used by the patient, that is, the objective function value is the difference between the irradiation angles achieved by the flash therapy machine and the angles required for fixed-field intensity-modulated therapy.

3. The method for distributing the angle of a treatment head for a multi-beam radiotherapy system according to claim 1, characterized in that: Assume that the number of beams used in the fixed field intensity modulation plan is M, and the beam angles are B1 to B M ; When M≤5, directly select M angles A1~A from n angles M , determine the overall rotation angle β of the frame; the value of β should minimize the following formula: For this minimization problem, the value of β should be (B i -A i )(1≤i≤M). In this way, the rack rotation angle β can be calculated for each angle selection scheme, thereby calculating the difference between the irradiation angle achieved by the flash therapy machine and the required irradiation angle. Compare the differences corresponding to the various angle selection schemes, and select the scheme with the smallest difference.

4. The method for distributing the angle of a treatment head for a multi-beam radiotherapy system according to claim 3, characterized in that: When M≥6, the M radiation beams are divided into C groups, with the number of radiation beams in each group not exceeding n. The beam angle and the overall rotation angle β selected when irradiating each group of radiation beams are determined separately, and the difference between the achieved angle and the angle required for treatment is calculated; the differences corresponding to each radiation beam grouping scheme are compared, and the scheme with the smallest difference is selected.

5. The method for distributing the angle of a treatment head for a multi-beam radiotherapy system according to claim 4, characterized in that: For a given relative angle relationship α1~α n-1 , use the enumeration method to calculate the minimum difference between the irradiation angle that the treatment head can achieve and the irradiation angle required by a set of fixed field intensity modulation plans. Then the optimization problem is: variables α1~α n-1 For which value the ray beam angle difference is minimal:

6. The method for distributing the angle of a treatment head for a multi-beam radiotherapy system according to any one of claims 1 to 5, characterized in that: Evaluate the consistency ΔG between the treatment angle provided by the treatment machine and the angle required for treatment: Where C represents the angle required to achieve treatment in C times, M i A represents the number of treatment angles included in the i-th treatment; ij represents the angle of the treatment head used in the i-th treatment, β i represents the overall rotation angle of the gantry for the i-th treatment, B ij represents the irradiation angle that needs to be achieved in the i-th treatment.

7. A treatment head angle distribution device for a multi-beam radiotherapy system, characterized in that: include: A modeling module uses a single variable to represent the angle of each treatment head, defines the restricted conditions of the angle distribution of the treatment head as the constraint conditions of the variable, defines the consistency between the treatment angle provided by the treatment machine and the angle required for treatment as the optimization objective function, and establishes an angle distribution optimization model; An acquisition module, used for acquiring the angle data of the ray beam used for treating the patient; A solution module is used to solve the acquired ray beam angle distribution data and the number of treatment heads to be arranged on the input treatment frame, as well as the restricted condition angle distribution optimization model of the treatment head angle distribution, to obtain the treatment head angle distribution result; The adjustment module is used to adjust the treatment head based on the obtained treatment head angle distribution result so that the treatment head is at the angle required for treatment.

8. A multi-beam radiotherapy system, characterized in that: It comprises the treatment head angle distribution device for a multi-beam radiotherapy system as described in claim 7, wherein the relative position relationship between the treatment heads of the multi-beam radiotherapy system is fixed, and the spacing between adjacent treatment heads is not the same, that is, a non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment heads of the multi-beam therapy system is adjusted by using the method described in any one of claims 1-5.

9. A flash beam radiotherapy machine, characterized in that: It comprises the treatment head angle distribution device for a multi-beam radiotherapy system as described in claim 7, wherein the multiple treatment heads of the flash beam radiotherapy machine are distributed on a circular frame, the multiple treatment heads can rotate with the circular frame as a whole, the spacing between adjacent treatment heads is fixed, and these spacings are not all the same, that is, non-equidistant treatment head angle distribution is adopted; the angle required for treatment of the treatment head of the flash beam radiotherapy machine is adjusted by using the method described in any one of claims 1-5.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes instructions for implementing the treatment head angle distribution method for a multi-beam radiotherapy system as described in any one of claims 1 to 6.

Images