High-precision ray flux calculation method based on radiotherapy plan control point interpolation

Abstract

The invention aims to provide a high-precision ray flux calculation method based on radiotherapy plan control point interpolation. The method comprises the following steps: acquiring a discrete control point sequence; selecting two control points to be interpolated; calculating the number of control points inserted between the two control points; and performing interpolation between the two control points according to the number of the inserted control points. By introducing the predictive control points between the original control points, the time resolution of the control point sequence is increased, and the accuracy of ray flux calculation can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of medical technology, and particularly relates to a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points. Background Art

[0002] A radiotherapy plan is an execution file for controlling a medical linear accelerator. The medical linear accelerator mobilizes the movement of various accelerator components and emits high-speed particle rays according to the instructions in the plan file. Control points are parameters in the plan file used to control the accelerator to be in a certain state at a certain moment. The movement process of each component inside the medical linear accelerator is described by an ordered and discrete sequence of control points. Flux is the distribution of the number of particles when the ray passes through a plane perpendicular to the beam output direction. Between two control points, due to the beam output of the accelerator, a flux distribution will be formed by the ray beam. In a medical linear accelerator, there are two important components: lead blocks and multi-leaf collimators (collectively referred to as collimators later), which are used to block rays so that the accelerator can obtain a very flexible flux distribution.

[0003] Currently, in order to calculate the required flux from the accelerator physical model and the radiotherapy plan file, the following two schemes are usually adopted: 1. Use the method of correcting the moving area at the end of the collimator to simulate the movement of the collimator between each control point; 2. Perform a specific convolution process on the generated flux to simulate the blurring effect caused by dynamics. The correction of the moving area at the end of the collimator is generally based on linear interpolation. For example, for the same collimator between two control points, the coverage range will change due to the position difference. Then, for the flux points in the part of the coverage range difference, the flux values generated by the two coverage states will be interpolated through linear interpolation to obtain an interpolation result, and thus a flux value that better simulates the movement of the collimator is obtained. The convolution process on the generated flux is generally based on a Gaussian convolution kernel to convolve the obtained flux. The method based on penumbra region correction needs to perform special processing on specific pixels, and is generally a correction of the flux calculation algorithm for early static three-dimensional conformal plans or static intensity-modulated plans. Since there was no control scheme of moving while emitting beams in the early radiotherapy plans, it was necessary to consider the movement of the collimator during beam output. However, due to the introduction of dynamic collimator technology, people designed a penumbra region correction scheme to calculate more accurate flux. However, this scheme has problems of insufficient accuracy in dynamic intensity-modulated plans and is not suitable for executing algorithms using high-performance computing devices such as GPUs. The method based on convolution of the generated flux has problems of difficult parameter adjustment and has not been widely used. Summary of the Invention

[0004] The object of the present invention is to provide a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points. By introducing predicted control points between the original control points, the time resolution of the control point sequence is increased, and the accuracy of ray flux calculation can be greatly improved.

[0005] A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points, comprising: Obtaining a discrete control point sequence; Selecting two control points for interpolation; Calculating the number of control points to be inserted between the two control points; Performing interpolation between the two control points according to the number of inserted control points.

[0006] Preferably, the obtaining of the discrete control point sequence includes: Obtaining the control parameters of the control points according to the plan file; Representing the control point sequence in vector form: ; where are the control parameters of the control points.

[0007] Preferably, the calculating of the number of control points to be inserted between the two control points includes: Obtaining the control parameters of the two control points; Calculating the number of inserted control points according to the control parameters.

[0008] Preferably, the obtaining of the control parameters of the two control points includes: Obtaining the position parameters and angle parameters of the control points.

[0009] Preferably, the calculating of the number of inserted control points according to the control parameters includes: The distance between the position parameters of the two control points , the distance between the angle parameters of the two control points ; Defining the maximum moving distance and defining the maximum moving angle ; The number of control points to be inserted ; where ceil represents rounding up and max represents taking the maximum of two numbers.

[0010] Preferably, the performing of interpolation between the two control points according to the number of inserted control points includes: Performing interpolation between the two control points in a linear interpolation manner: A high-precision ray flux calculation system based on interpolation of radiotherapy plan control points, comprising: A data acquisition module, configured to acquire a discrete control point sequence; A control point selection module, configured to select two control points for interpolation; A data processing module, configured to calculate the number of control points inserted between two control points; An interpolation module, configured to perform interpolation between two control points according to the number of inserted control points.

[0011] An electronic device, comprising: a chip, a processor, and a memory, where the memory is used to store computer program code, and the computer program code includes computer instructions. When the chip executes the computer instructions, the electronic device executes a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points.

[0012] A computer-readable storage medium stores a computer program, and the computer program includes program instructions. When the program instructions are executed by a processor of an electronic device, the processor is caused to execute a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points.

[0013] The beneficial effects of the present invention are as follows: 1. By mapping control point parameters to a vector space, linear operations can be performed; 2. The time resolution of the original plan control point sequence is improved, thereby improving the accuracy of flux calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings herein are incorporated into the specification and form a part of the specification, indicating embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for description in the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a flowchart of a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to the present invention; Figure 2 It is a schematic diagram of inserting control points according to the present invention; Figure 3 It is a schematic diagram of the hardware structure of an electronic device according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0018] It should be noted that all directional indications (such as up, down, left, right, front, back,...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0019] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] Currently, in order to calculate the required flux deduced from the accelerator physical model and radiotherapy plan files, the following two schemes are usually adopted: 1. Using the method of correcting the moving area at the end of the collimator to simulate the movement of the collimator between each control point; 2. Performing specific convolution processing on the generated flux to simulate the blurring effect caused by dynamics. The correction of the moving area at the end of the collimator is generally based on linear interpolation. For example, the coverage range of the same collimator between two control points will change due to position differences. Then, for the flux points in the part of the coverage range difference, the flux values generated by the two coverage states will be interpolated through linear interpolation to obtain an interpolation result, and then a flux value better simulating the movement of the collimator is obtained. The convolution processing of the generated flux is generally based on a Gaussian convolution kernel to convolve the obtained flux. The method based on penumbra correction needs to perform special processing on specific pixels. Generally, it is a correction of the flux calculation algorithm for early static three-dimensional conformal plans or static intensity-modulated plans. Since there was no control scheme for moving during beam delivery in the early radiotherapy plans, it was necessary to consider the movement of the collimator during beam delivery. However, due to the introduction of dynamic collimator technology, a penumbra correction scheme was designed to calculate more accurate flux. However, this scheme has problems of insufficient accuracy in dynamic intensity-modulated plans and is not suitable for executing algorithms using high-performance computing devices such as GPUs. The method based on the convolution of the generated flux has problems of difficult parameter adjustment and has not been widely used.

[0021] The present invention maps the control point parameters to a vector space, and then linear operations can be performed; the present invention improves the time resolution of the original plan control point sequence, and thus improves the accuracy of flux calculation.

[0022] Embodiment 1 A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points, referring to Figure 1 , comprising: S100, obtaining a discrete control point sequence; S200, selecting two control points for interpolation; S300, calculating the number of control points inserted between the two control points; S400, performing interpolation between the two control points according to the number of inserted control points.

[0023] The radiotherapy plan file is a digital document that records the patient's treatment parameters, dose calculation data, and equipment configuration, and is used to ensure the precise execution of radiotherapy (such as IMRT, VMAT, SBRT, etc.). The radiotherapy plan file usually contains the following key modules: Patient information: Name, ID, diagnosis (such as tumor location, stage). Type of immobilization device (such as thermoplastic film, vacuum cushion). Imaging data: CT / MRI / PET-CT images: Used for target delineation and dose calculation, containing DICOM format slice thickness and resolution information. Structure set: Target areas (GTV, CTV, PTV). Contours of organs at risk such as the spinal cord, lungs, and rectum. Treatment parameters: Beam settings: Gantry angle, collimator angle, couch angle. Beam shape (defined by the MLC blade positions) and weights. Dose constraints: Target prescription dose and OARs limits. Dose calculation data: Dose distribution matrix: Dose values in a three-dimensional grid. Dose volume histogram: Quantifies the dose coverage of the target area and OARs. Equipment configuration: Accelerator model, energy selection, and treatment mode.

[0024] The radiotherapy plan file details the specific parameters of radiotherapy, such as the type of radiation, energy, size, shape, position of the irradiation field, as well as the irradiation dose and time, etc. These parameters are precisely determined based on factors such as the patient's tumor location, size, shape, and the relationship with surrounding normal tissues, ensuring that the radiation can accurately irradiate the tumor tissue while minimizing damage to the surrounding normal tissues.

[0025] Preferably, for S100, obtaining a discrete sequence of control points includes: Obtaining the control parameters of the control points according to the plan file; Representing the sequence of control points in vector form: ; wherein, are the control parameters of the control points.

[0026] The control points of the radiotherapy plan are a discrete sequence of control points. Then, for each control point, various parameters can be mapped to a set of geometric parameters, and thus it can be represented by a vector. For example, at the control points, there are the positions of each lead block, the positions of each multi-leaf collimator, the rotation angle of the head, the rotation angle of the gantry, etc. This set of parameters can be mapped to a vector, enabling linear operations. At this time, the sequence of control points is a sequence of vectors.

[0027] Preferably, for S300, calculating the number of control points inserted between two control points includes: S310, obtaining the control parameters of the two control points; The control points are in the planning document and are a set of parameters used to control the accelerator to be in a certain state at a certain moment. The movement processes of various components inside a medical linear accelerator are described by an ordered and discrete sequence of control points. Reasonable setting of control points helps to achieve local control of tumors and improve the cure rate and survival rate of patients. For example, accurate target area determination and optimized dose distribution can ensure that tumor cells receive lethal irradiation, without tumor recurrence due to insufficient dose or affecting subsequent treatment due to excessive dose causing normal tissue complications. Control points such as the protection of organs at risk and the strict calibration of machine parameters can effectively reduce the risk of serious damage to normal tissues during radiotherapy and ensure the safety of patients. Important organs such as the spinal cord have low tolerance to radiation. By setting dose limit conditions, it is possible to avoid spinal cord injury caused by excessive irradiation dose and complications such as serious neurological dysfunction. The various control points of a radiotherapy plan do not exist in isolation, but are interrelated and interact with each other. When formulating and adjusting a radiotherapy plan, by comprehensively evaluating and optimizing these control points, the most suitable treatment plan can be formulated according to the specific situation of the patient.

[0028] S320, calculate the number of inserted control points according to the control parameters.

[0029] There are many control parameters for the control points of radiotherapy plans, including parameters related to the target area, organs at risk, dose, beam, etc. Target area-related parameters include gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV), as well as the location of the target area. Organ-at-risk-related parameters include the three-dimensional spatial range of the organ at risk and its specific location in the body, the relative positional relationship with the target area, and different organs at risk have different tolerances to radiation, with their own dose limit parameters, such as the maximum tolerance dose of the spinal cord, the average dose limit of the lungs, the local dose limit of the heart, etc. Dose-related parameters: The prescribed dose refers to the specific absorbed dose planned to be given to the target area, usually determined based on factors such as the type and stage of the tumor and the patient's physical condition. Dose distribution parameters: include dose uniformity, dose gradient, etc. Dose uniformity requires the dose distribution within the target area to be as uniform as possible, avoiding areas with too high or too low doses, and is generally measured by the uniformity index. The dose gradient describes the rate of dose change from the edge of the target area to the surrounding normal tissue. Ideally, it is hoped that the dose drops rapidly at the edge of the target area to reduce the irradiation of normal tissue. Beam-related parameters: Beam energy: Different tumor depths and types require the selection of appropriate beam energies, such as high-energy X-rays, electron beams, etc. The higher the energy, the stronger the penetration ability of the beam, which is suitable for deep tumors; lower-energy beams are suitable for superficial tumors. Beam angle and direction: According to the positional relationship between the target area and the organs at risk, select the appropriate beam incidence angle and direction to avoid the organs at risk and at the same time make the beam pass through the target area as much as possible. By simulating the irradiation of the target area and surrounding tissues by beams at different angles through the treatment planning system, the beam angle combination is optimized, such as using multi-field irradiation technology to irradiate the target area from different directions to improve the dose uniformity and conformity of the target area. Beam intensity distribution: In techniques such as intensity-modulated radiotherapy and volumetric modulated arc therapy, it is necessary to precisely control the intensity distribution of the beam at different positions. By adjusting the movement of the leaves of the multi-leaf collimator and the ray output time, the beam intensity changes according to the planned requirements, thereby achieving a more accurate dose distribution, better protecting the organs at risk, and improving the dose conformity of the target area.

[0030] Preferably, in S310, obtaining the control parameters of two control points includes: Obtaining the position parameters and angle parameters of the control points.

[0031] In the embodiment of the present invention, from the above-mentioned multiple control parameters, the position parameters and angle parameters of the control points are selected. There is a certain position gap and angle gap between two control points. Among the position gap and angle gap, multiple control points can be inserted. Therefore, the present invention calculates the number of control points that can be inserted based on the position gap and angle gap between two control points. By inserting multiple control points, compared with the original small number of control points, the data volume is greatly enhanced, more flux information can be provided, and it is beneficial to obtain a more accurate flux distribution.

[0032] Preferably, in S320, calculating the number of inserted control points according to the control parameters includes: The distance between the position parameters of two control points , and the distance between the angle parameters of two control points ; Defining the maximum movement distance , and defining the maximum movement angle ; The number of control points to be inserted ; wherein, ceil represents rounding up, and max represents taking the maximum value of two numbers.

[0033] In the embodiments of the present invention, the basis for determining the number of inserted control points includes the maximum movement distance, the maximum movement angle, the minimum beam output, etc. For example, according to the constraints that the maximum movement distance does not exceed 2 mm, the maximum movement angle does not exceed 2 degrees, and the minimum beam output is not less than 0.5% of the total beam output, the number of control points to be inserted is determined.

[0034] Preferably, in S400, interpolating between two control points according to the number of inserted control points includes: Performing interpolation between two control points in a linear interpolation manner: .

[0035] After obtaining the number of control points to be inserted, many predicted control points can be inserted between two control points in the planning file. If it is assumed that each component moves at a constant speed between two control points, a simple linear interpolation method can be used. After determining the number of control points to be inserted, the present invention uses the linear interpolation described in the mathematical model to insert an ordered sequence of predicted control points, and finally generates a control point sequence with higher time resolution.

[0036] Linear interpolation can estimate the missing data based on the existing data points, so as to fill and repair the data, make the data more complete, and facilitate subsequent analysis and processing. Linear interpolation is often used to fit discrete data points to obtain a continuous function approximation expression for numerical calculation and analysis. In the case where the medical component moves at a constant speed, the effect of linear interpolation is the best, and the present invention can also select other interpolation methods according to the actual situation to optimize the data.

[0037] Embodiment 2 A high-precision ray flux calculation system based on radiotherapy plan control point interpolation, comprising: A data acquisition module, configured to acquire a discrete control point sequence; A control point selection module, configured to select two control points for interpolation; A data processing module, configured to calculate the number of control points to be inserted between two control points; An interpolation module, configured to perform interpolation between two control points according to the number of inserted control points.

[0038] Embodiment 3 An electronic device includes: a chip, a processor, and a memory. The memory is used to store computer program code, and the computer program code includes computer instructions. When the chip executes the computer instructions, the electronic device executes a high-precision ray flux calculation method based on radiotherapy plan control point interpolation.

[0039] Reference Figure 3 , the electronic device 2 includes a processor 21, a memory 22, an input device 23, and an output device 24. The processor 21, the memory 22, the input device 23, and the output device 24 are coupled through a connector, and the connector includes various interfaces, transmission lines, or buses, etc., which are not limited in the embodiments of the present invention. It should be understood that in various embodiments of the present invention, coupling means being interconnected in a specific manner, including being directly connected or indirectly connected through other devices, for example, being connected through various interfaces, transmission lines, buses, etc.

[0040] The processor 21 may be one or more graphics processing units (GPUs). When the processor 21 is a single GPU, the GPU may be a single-core GPU or a multi-core GPU. Optionally, the processor 21 may be a processor group composed of multiple GPUs, and multiple processors are coupled to each other through one or more buses. Optionally, the processor may also be other types of processors, etc., which are not limited in the embodiments of the present invention.

[0041] The memory 22 may be used to store computer program instructions and various computer program codes including the program code for implementing the solution of the present invention. Optionally, the memory includes, but is not limited to, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or a compact disc read-only memory (CD-ROM), and the memory is used for relevant instructions and data.

[0042] An input device 23 is used for inputting data and / or signals, and an output device 24 is used for outputting data and / or signals. The output device 24 and the input device 23 can be independent devices or an integral device.

[0043] Embodiment 4 A computer-readable storage medium stores a computer program, and the computer program includes program instructions. When the program instructions are executed by a processor of an electronic device, the processor is caused to execute a high-precision ray flux calculation method based on interpolation of radiotherapy plan control points.

[0044] In the present invention, control point parameters are mapped to a vector space, and then linear operations can be performed; the present invention improves the time resolution of the original planned control point sequence, and thus improves the accuracy of flux calculation.

[0045] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points, characterized in that, Including: Obtaining a discrete sequence of control points; Selecting two control points for interpolation; Calculating the number of control points to be inserted between two control points; Performing interpolation between two control points according to the number of inserted control points.

2. The high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to claim 1, wherein The obtaining of the discrete sequence of control points includes: Obtaining the control parameters of the control points according to the plan file; Representing the control point sequence in vector form: ； Among them, is the control parameter of the control point.

3. A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to claim 1, characterized in that The calculating of the number of control points to be inserted between two control points includes: Obtaining the control parameters of two control points; Calculating the number of inserted control points according to the control parameters.

4. A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to claim 3, characterized in that The obtaining of the control parameters of two control points includes: Obtaining the position parameters and angle parameters of the control points.

5. A high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to claim 3, characterized in that, The calculating of the number of inserted control points according to the control parameters includes: The distance of the position parameters of two control points , the distance of the angular parameters of two control points ; Limit the maximum moving distance and limit the maximum moving angle ; Number of control points to be inserted ; Where ceil represents rounding up, and max represents taking the maximum of two numbers.

6. The high-precision ray flux calculation method based on interpolation of radiotherapy plan control points according to claim 1, wherein, The performing of interpolation between two control points according to the number of inserted control points includes: Performing interpolation between two control points in a linear interpolation manner: 。 7. A high-precision ray flux calculation system based on interpolation of radiotherapy plan control points, characterized in that, Including: A data acquisition module for obtaining a discrete sequence of control points; A control point selection module for selecting two control points for interpolation; A data processing module for calculating the number of control points to be inserted between two control points; An interpolation module for performing interpolation between two control points according to the number of inserted control points.

8. An electronic device, characterized in that, Including: A chip, a processor, and a memory, where the memory is used to store computer program code, and the computer program code includes computer instructions. When the chip executes the computer instructions, the electronic device executes a high-precision ray flux calculation method according to any one of claims 1 to 6 based on radiotherapy plan control point interpolation.

9. A computer-readable storage medium, characterized in that, A computer program is stored in the computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by the processor of the electronic device, the processor is caused to execute a high-precision ray flux calculation method according to any one of claims 1 to 6 based on radiotherapy plan control point interpolation.

Images