A control system for a medical accelerator and a medical accelerator

Abstract

This invention discloses a control system and a medical accelerator. The control system includes an acceleration unit and a control unit. The acceleration unit is electrically connected to the control unit. The control unit is configured to acquire the radio frequency power signal of the acceleration unit and determine the radio frequency control signal of the acceleration unit based on the whale optimization algorithm. The acceleration unit is configured to accelerate charged particles based on the radio frequency control signal. This invention solves the technical problems of long adjustment time, slow dynamic response, and insufficient anti-interference capability in existing medical accelerators using traditional PI controllers for parameter control by replacing the PI controller of a traditional low-level control system with an adaptive PI controller based on the whale optimization algorithm. This achieves the technical effect of improving the robustness and adaptability of the control system.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and in particular to a control system and a medical accelerator. Background Technology

[0002] Medical accelerators, as core equipment in tumor radiotherapy, accelerate charged particles (such as electrons and protons) using electromagnetic fields. These particles gain high energy and then bombard target materials or directly act on the lesion area, generating high-energy rays (such as X-rays and gamma rays) required for treatment. Currently, mainstream medical accelerators include linear electron accelerators and cyclotron accelerators, whose performance depends on precise control of the radiofrequency power signal within the accelerating cavity.

[0003] In accelerator systems, the Low-Level Radio Frequency (LLRF) control system plays a crucial role in real-time regulation of the amplitude and phase of the radio frequency power signal to ensure energy stability and beam quality during particle acceleration. Traditional LLRF control often employs classic proportional-integral (PI) controllers, whose parameter tuning relies on manual experience or offline debugging based on system models. However, medical accelerators face challenges such as complex electromagnetic disturbances and dynamic changes in cavity load during actual operation. Especially when the system model is unknown or exhibits significant nonlinear characteristics, traditional methods suffer from long adjustment times, lag in dynamic response, and insufficient anti-interference capabilities, easily leading to fluctuations in accelerator output energy and affecting treatment efficacy and equipment safety.

[0004] Therefore, how to quickly generate optimal PI control parameters and achieve adaptive and intelligent adjustment of the LLRF system without a precise system model has become a key technical challenge to improve the control accuracy and reliability of medical accelerators. Utility Model Content

[0005] This utility model provides a control system and a medical accelerator, which solves the technical problems of long adjustment time, slow dynamic response, and insufficient anti-interference ability in the existing medical accelerators that use traditional PI controllers for parameter control.

[0006] This utility model provides a control system for a medical accelerator, the control system including an acceleration unit and a control unit;

[0007] The acceleration unit is electrically connected to the control unit;

[0008] The control unit is configured to acquire the radio frequency power signal of the acceleration unit and determine the radio frequency control signal of the acceleration unit based on the whale optimization algorithm using the radio frequency power signal.

[0009] The acceleration unit is configured to accelerate charged particles based on the radio frequency control signal.

[0010] Furthermore, the acceleration unit includes at least two acceleration paths; the control unit includes at least two control components;

[0011] The output terminal of one acceleration path is connected to the input terminal of one control component; the output terminal of the control component is electrically connected to the feedback control terminal of the acceleration unit.

[0012] Each of the control components includes two PI controllers configured to determine the control signals for the acceleration unit based on the whale optimization algorithm.

[0013] Furthermore, the control system also includes a power amplifier component;

[0014] The output terminals of each of the control components are electrically connected to the feedback control terminal of the acceleration unit via the power amplification component.

[0015] Furthermore, the acceleration path includes a power source, a feed tube, a coupling loop, and an acceleration cavity;

[0016] The input terminal of the power source is electrically connected to the power amplifier component as the feedback control terminal of the acceleration unit.

[0017] The output terminal of the power source is sequentially connected to the feed tube, the coupling loop, and the accelerator;

[0018] The output terminal of the accelerator is electrically connected to the input terminal of the control component, serving as the output terminal of the acceleration unit.

[0019] Furthermore, the power source includes:

[0020] First-stage amplifier: used to amplify the radio frequency control signal output by the power amplification component in one step;

[0021] A secondary amplifier; used to amplify the radio frequency control signal a second time after the first amplification;

[0022] A directional coupler is used to monitor the power, frequency, and VSWR of the power source in real time based on the amplified radio frequency control signal.

[0023] Furthermore, the control component includes:

[0024] A cavity sampling module, which serves as the input terminal of the control component, is used to acquire the radio frequency power signal of the acceleration unit;

[0025] A digital downconversion module is used to convert the radio frequency power signal into in-phase and quadrature component signals;

[0026] The signal comparison module is used to compare the in-phase component signal and the quadrature component signal with a set in-phase signal and a set quadrature signal, respectively, and send the obtained in-phase difference value and quadrature difference value to a PI controller.

[0027] Furthermore, the control component also includes:

[0028] The digital upconversion module is used to quadrature the control signals output by the two PI controllers to obtain a radio frequency control signal, and then transmit the radio frequency control signal to the power amplifier component.

[0029] Furthermore, the control system also includes a clock generation component;

[0030] The cavity sampling module in each of the control components is electrically connected to the clock generating component.

[0031] This utility model embodiment also provides a medical accelerator, which includes the control system of the medical accelerator described in any of the above embodiments.

[0032] This invention discloses a control system and a medical accelerator. The control system includes an acceleration unit and a control unit. The acceleration unit is electrically connected to the control unit. The control unit is configured to acquire the radio frequency power signal of the acceleration unit and determine the radio frequency control signal of the acceleration unit based on the whale optimization algorithm. The acceleration unit is configured to accelerate charged particles based on the radio frequency control signal. This invention solves the technical problems of long adjustment time, slow dynamic response, and insufficient anti-interference capability in existing medical accelerators using traditional PI controllers for parameter control by replacing the PI controller of a traditional low-level control system with an adaptive PI controller based on the whale optimization algorithm. This achieves the technical effect of improving the robustness and adaptability of the control system. Attached Figure Description

[0033] Figure 1 This is a structural diagram of a control system for a medical accelerator provided in an embodiment of this utility model;

[0034] Figure 2 This is a flowchart illustrating the implementation of the whale optimization algorithm in the PI controller provided in this embodiment of the utility model.

[0035] Figure 3 This is a fitness convergence curve provided in an embodiment of the present invention;

[0036] Figure 4This is a step response curve provided in an embodiment of the present invention. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this utility model are used to distinguish different objects, not to limit a specific order. The various embodiments of this utility model described below can be performed individually, or they can be combined with each other; this utility model does not impose specific limitations in this regard.

[0039] Figure 1 This is a structural diagram of a control system for a medical accelerator provided in an embodiment of this utility model.

[0040] like Figure 1 As shown, the control system of the medical accelerator includes an acceleration unit 100 and a control unit 200; the acceleration unit 100 and the control unit 200 are electrically connected.

[0041] The control unit 200 is configured to acquire the radio frequency power signal of the acceleration unit 100 and determine the radio frequency control signal of the acceleration unit 100 based on the whale optimization algorithm using the radio frequency power signal; the acceleration unit 100 is configured to accelerate charged particles based on the radio frequency control signal.

[0042] Specifically, the Whale Optimization Algorithm (WOA) is a novel swarm intelligence optimization algorithm inspired by the hunting behavior of humpback whales. It boasts advantages such as conceptual simplicity, few parameters, and ease of implementation, and has wide applications in function optimization, engineering design, and machine learning. Humpback whales exhibit unique hunting behaviors, primarily including three types: surrounding prey, spiraling position updates, and random prey searches. The WOA algorithm simulates these three behaviors to search for the optimal solution.

[0043] Specifically, "surrounding prey" refers to the humpback whale gradually approaching and surrounding its prey after spotting it. In the algorithm, this corresponds to the process of the search individual moving closer to the current optimal solution. "Spiral position update" refers to the humpback whale swimming along a spiral path, gradually approaching the prey. The algorithm simulates this spiral movement to enable the search individual to explore the search space more effectively. "Random prey search" refers to the humpback whale randomly swimming within the search area when it does not find clear prey, looking for potential prey. In the algorithm, this is reflected in the search individual randomly moving within the search space to expand the search range and avoid getting trapped in local optima.

[0044] Based on the aforementioned characteristics of the whale optimization algorithm, when the RF power signal from the acceleration unit 100 enters the control unit 200, the control unit 200 first converts the RF power signal... Converted into two quadrature components, which are in-phase signal components. and orthogonal component signals Then the in-phase component signal orthogonal component signals The signals are compared with the set in-phase signal and the set quadrature signal respectively to obtain the in-phase difference value and the quadrature difference value. The obtained in-phase difference value and quadrature difference value are then sent to the PI controller on their respective paths. The PI controller will use the whale optimization algorithm to find the optimal PI controller parameters in a relatively short time through a random search mechanism to an encirclement search mechanism, and then through a bubble net predation mechanism. The output of the PI controller parameters is sent to the acceleration unit 100 to regulate the amplitude and phase of the acceleration unit 100, thereby shortening the adjustment time, speeding up the dynamic response, and improving the anti-interference capability of the system.

[0045] This invention solves the technical problems of long adjustment time, slow dynamic response, and insufficient anti-interference ability in medical accelerators using traditional PI controllers for parameter control by replacing the PI controller in the traditional low-level control system with an adaptive PI controller based on the whale optimization algorithm. This achieves the technical effect of improving the robustness and adaptability of the control system.

[0046] Optionally, such as Figure 1 As shown, the acceleration unit 100 includes at least two acceleration paths 101; the control unit 200 includes at least two control components 201; the output terminal of one acceleration path 101 is connected to the input terminal of one control component 201; the output terminal of the control component 201 is electrically connected to the feedback control terminal of the acceleration unit 100.

[0047] Each control component 201 includes two PI controllers 24, which are configured to determine the control signal for the acceleration unit 100 based on the whale optimization algorithm.

[0048] In one medical accelerator control system, multiple acceleration control paths can be configured. Each acceleration control path includes one control component 201 in the control unit 200 and one acceleration path 101 in the acceleration unit 100. One control component 201 controls one acceleration path 101. Figure 1 The diagram above provides an example of a configuration with two acceleration control paths.

[0049] Specifically, Figure 2 This describes the implementation flow of the whale optimization algorithm in the PI controller 24 provided in this embodiment of the utility model. For example... Figure 2 As shown, the specific steps include the following:

[0050] S201, Set the number of whales in the algorithm and the maximum number of iterations. In this embodiment of the invention, the number of whales is set to 50 and the maximum number of iterations is set to 200.

[0051] S202, calculate individual fitness based on a preset individual fitness function. In this embodiment of the invention, the ISE (Integral of Squared Error) index ∫e is selected. 2 The signal (t)dt serves as the fitness function of the system;

[0052] S203: Determine whether the system meets the optimization criteria, i.e., whether the maximum number of iterations has been reached. If it does, execute S204 to output the optimal solution and exit the optimization; otherwise, proceed to S205.

[0053] S204: Output the optimal solution and exit optimization.

[0054] S205, Generate a random number P, and update A and C according to the formula of the whale optimization algorithm. A is used to control the position of the whale, update the direction and step size, and C is used to affect the search range and direction of the whale. It decreases linearly from 2 to 0; It is a random number that is randomly distributed within [0,1].

[0055] S206, determine if the random number P is less than 0.5. If it is less than 0.5, execute S207; otherwise, execute S210.

[0056] S207, determine if the absolute value of A, |A|, is less than 1. If it is less than 1, execute S208; otherwise, execute S209.

[0057] S208, Update the individual position according to the encirclement search mechanism formula: Returning to S202, where X best This represents the globally optimal individual position in the current iteration.

[0058] S209, Update the individual position according to the random search mechanism formula: Returning to S202, where X rand The location of an individual randomly selected within the population.

[0059] S210, update individual position according to the spiral bubble net predation mechanism formula: Returning to S202, b is the spiral shape constant, which controls the tightness of the spiral path and is usually a fixed value, and l is a random number in the interval [-1,1], which is used to determine the direction and step size of the spiral motion.

[0060] Based on the control process of the whale optimization algorithm described above, we can obtain... Figure 3 The fitness convergence curve shown in the figure, and Figure 4 The step response curve shown is Figure 4 The rin curve in the figure represents the unit step signal curve, and the WOA-PI curve represents the step response curve output by the PI controller based on the whale optimization algorithm. Figure 3 and Figure 4 It can be seen that the system fitness converges in a very short time, and the output signal has a very low overshoot relative to the step response. By using a PI controller based on the whale optimization algorithm, the optimal control parameters of the PI controller can be found in a relatively short time through a random search mechanism, a surrounding search mechanism, and then a bubble net predation mechanism.

[0061] Optionally, such as Figure 1 As shown, the control system also includes a power amplifier component 300; the output terminals of each control component 201 are electrically connected to the feedback control terminal of the acceleration unit 100 through the power amplifier component 300.

[0062] Specifically, the power amplifier component 300 is used to amplify the radio frequency control signal output by the PI controller 24 within a small range before sending it into the acceleration unit 100. For example, the power amplifier component 300 is used to amplify the power of the 78MHz radio frequency control signal output by the control and component 201 by 10dBm.

[0063] Optionally, such as Figure 1 As shown, the acceleration path 101 includes a power source 11, a feed tube 12, a coupling ring 13, and an acceleration cavity 14.

[0064] The input terminal of the power source 11 is electrically connected to the power amplifier component 300 as the feedback control terminal of the acceleration unit 100; the output terminal of the power source 11 is sequentially connected to the feed tube 12, the coupling ring 13 and the accelerator 14; the output terminal of the accelerator 14 is electrically connected to the input terminal of the control component 201 as the output terminal of the acceleration unit 100.

[0065] Specifically, the power source 11 generates a high-frequency microwave electric field based on the internally installed magnetron or klystron to provide driving energy for the acceleration cavity 14. Among them, the magnetron is mostly used in traveling wave and low-energy accelerators, while the klystron is used in medium and high-energy standing wave accelerators. On the other hand, the power source 11 can receive the radio frequency control signal sent by the control component 201 and amplify the radio frequency control signal.

[0066] As part of the waveguide system, the feed tube 12 directionally transmits the microwave energy generated by the power source 11 to the accelerating cavity 14, ensuring energy transfer efficiency. The coupling ring 13 is used to efficiently couple the microwave energy transmitted by the feed tube 12 to the accelerating cavity 14, ensuring uniform electromagnetic field distribution and avoiding local energy loss.

[0067] Optionally, such as Figure 1 As shown, the power source 11 includes:

[0068] First-stage amplifier 111: used to amplify the radio frequency control signal output from the power amplifier component 300;

[0069] Secondary amplifier 112; used to amplify the RF control signal a second time after primary amplification;

[0070] The directional coupler 113 is used to monitor the power, frequency and VSWR of a power source in real time based on the amplified radio frequency control signal.

[0071] Specifically, the first-stage amplifier 111 is a driver-stage amplifier. On the one hand, it generates an initial microwave signal through a magnetron or klystron. On the other hand, it serves as the feedback control terminal of the acceleration unit to receive the radio frequency control signal and complete the primary power amplification of the radio frequency control signal, providing a stable high-frequency electromagnetic field for the acceleration cavity 14. The second-stage amplifier 112 is a final-stage amplifier, used to perform the final power amplification of the microwave signal generated by the first-stage amplifier 111, as well as the secondary amplification of the radio frequency control signal, and inject a high-energy electromagnetic field into the acceleration cavity 14 so that the electron beam energy reaches the level required for treatment. The directional coupler 113 couples part of the radio frequency control signal from the main transmission waveguide, used to monitor the power, frequency, and standing wave ratio in real time to ensure the matching state between the microwave source and the acceleration cavity 14.

[0072] Optionally, such as Figure 1 As shown, the control component 201 includes:

[0073] The cavity sampling (pick-up AD) module 21 serves as the input terminal of the control component and is used to acquire the radio frequency power signal of the acceleration unit.

[0074] The Digital Down Converter (DDC) module 22 is used to convert radio frequency power signals into in-phase and quadrature component signals;

[0075] The signal comparison module 23 is used to compare the in-phase component signal and the quadrature component signal with the set in-phase signal and the set quadrature signal, respectively, and send the obtained in-phase difference value and quadrature difference value to a PI controller.

[0076] Specifically, the high-energy signal of hundreds of kilowatts undergoes attenuation of tens of dB after passing through coupling loop 13. This attenuated signal then enters the accelerating cavity 14 as a low-energy signal, where it is sampled by cavity sampling module 21 to obtain the radio frequency power signal. The clock frequency used can be 78 * 11 / 8 = 107.25 MHz. The signal enters the digital downconverter module 22 for orthogonal decomposition to obtain the I-channel signal. and Q-channel signal That is, the aforementioned in-phase component signal and quadrature component signal. Among them, the in-phase component signal... Used to reflect the signal amplitude A and phase Cosine relationship, orthogonal component signal The sinusoidal component is used to provide phase information.

[0077] Then the in-phase component signal A signal comparison module 23 is sent to the set in-phase signal (i.e., Figure 1 The in-phase difference value is obtained by comparing the Set point I shown; the quadrature component signals are then compared. A signal comparison module 23 is fed in and a set quadrature signal (i.e., Figure 1 The orthogonal difference value is obtained by comparing the Set point Q shown in the figure.

[0078] Due to the in-phase component signal It needs to be as close as possible to the set in-phase signal and quadrature component signal. To get as close as possible to the set quadrature signal, the in-phase difference and quadrature difference are sent to the PI controller 24 on their respective paths, and the optimal control parameters are obtained by using the whale optimization algorithm.

[0079] Optionally, such as Figure 1 As shown, the control component 201 also includes:

[0080] The Digital Up Converter (DUC) module 25 is used to quadrature modulate the control signals output by the two PI controllers to obtain the radio frequency control signal, and then transmit the radio frequency control signal to the power amplifier component 300.

[0081] Specifically, since signal transmission requires a carrier state, after the PI controller 24 outputs the control signal, the digital up-conversion module 25 is needed to quadrature-modulate the two control signals to obtain the radio frequency control signal. The radio frequency (RF) control signal is a small energy signal of approximately 1V. This RF control signal is then fed into the power amplifier component 300 for amplification within a small range of approximately 10V. Finally, the approximately 10V RF control signal is sent to the power source for further amplification.

[0082] Optionally, such as Figure 1 As shown, the control system also includes a clock generation component 400;

[0083] The cavity sampling module 21 in each control component 201 is electrically connected to the clock generation component 400.

[0084] Specifically, the clock generation component 400 is used to generate a clock signal to provide a precise time reference for the cavity sampling module 21, thereby improving the accuracy of sampling.

[0085] This utility model embodiment also provides a medical accelerator, which includes the control system of the medical accelerator in any of the above embodiments.

[0086] The medical accelerator provided in this embodiment includes the control system of the medical accelerator in the above embodiment. Therefore, the medical accelerator provided in this embodiment also has the beneficial effects described in the above embodiment, which will not be repeated here.

[0087] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0088] Finally, it should be noted that the above are merely preferred embodiments and the technical principles applied in this utility model. Those skilled in the art will understand that this utility model is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the protection scope of this utility model. Therefore, although the utility model has been described in detail through the above embodiments, this utility model is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of this utility model, and the scope of this utility model is determined by the scope of the appended claims.

Claims

1. A control system for a medical accelerator, characterized by, The control system includes an acceleration unit and a control unit; The acceleration unit is electrically connected to the control unit; The control unit is configured to acquire the radio frequency power signal of the acceleration unit and determine the radio frequency control signal of the acceleration unit based on the whale optimization algorithm using the radio frequency power signal. The acceleration unit is configured to accelerate charged particles based on the radio frequency control signal.

2. The control system of the medical accelerator according to claim 1, characterized in that, The acceleration unit includes at least two acceleration paths; the control unit includes at least two control components. The output terminal of one acceleration path is connected to the input terminal of one control component; the output terminal of the control component is electrically connected to the feedback control terminal of the acceleration unit. Each of the control components includes two PI controllers configured to determine the control signals for the acceleration unit based on the whale optimization algorithm.

3. The control system of a medical accelerator according to claim 2, wherein, The control system also includes a power amplifier component; The output terminals of each of the control components are electrically connected to the feedback control terminal of the acceleration unit via the power amplification component.

4. The control system of a medical accelerator according to claim 3, wherein The acceleration path includes a power source, a feed tube, a coupling loop, and an acceleration cavity; The input terminal of the power source is electrically connected to the power amplifier component as the feedback control terminal of the acceleration unit. The output terminal of the power source is sequentially connected to the feed tube, the coupling loop, and the accelerator; The output terminal of the accelerator is electrically connected to the input terminal of the control component, serving as the output terminal of the acceleration unit.

5. The control system of a medical accelerator according to claim 4, wherein, The power source includes: First-stage amplifier: used to amplify the radio frequency control signal output by the power amplification component in one step; A secondary amplifier; used to amplify the radio frequency control signal a second time after the first amplification; A directional coupler is used to monitor the power, frequency, and VSWR of the power source in real time based on the amplified radio frequency control signal.

6. The control system of a medical accelerator according to claim 3, wherein The control component includes: A cavity sampling module, which serves as the input terminal of the control component, is used to acquire the radio frequency power signal of the acceleration unit; A digital downconversion module is used to convert the radio frequency power signal into in-phase component signal and quadrature component signal; The signal comparison module is used to compare the in-phase component signal and the quadrature component signal with a set in-phase signal and a set quadrature signal, respectively, and send the obtained in-phase difference value and quadrature difference value to a PI controller.

7. The control system of a medical accelerator according to claim 3, wherein The control component also includes: The digital upconversion module is used to quadrature the control signals output by the two PI controllers to obtain a radio frequency control signal, and then transmit the radio frequency control signal to the power amplifier component.

8. The control system of a medical accelerator according to claim 6, wherein, The control system also includes a clock generation component; The cavity sampling module in each of the control components is electrically connected to the clock generating component.

9. A medical accelerator characterized by, The medical accelerator includes the control system of the medical accelerator as described in any one of claims 1 to 8.

Images