A proton beam energy selection control system

Abstract

A kind of proton beam energy selection control system, including system board card, motion board card, energy reducer, multiple four-fan collimators, multiple magnets, the multiple magnets include four-stage magnet, guide magnet and deflection magnet;The system board card includes multitask scheduling unit with synchronous motion instruction transmission module, when the initialization process of multiple tasks is started in the asynchronous mode of head-to-tail connection, the module receives scheduling instruction by the way of instruction transmission, so that the multitask module started in asynchronous mode receives scheduling instruction at the same time;The energy selection control system controls the energy reduction response time of each gear of energy reducer, which is faster than the response time of multiple wedge-shaped energy reducer, and can complete energy switching within 50 milliseconds;The present application solves the problem of long communication time of existing technology instruction issued to each device of beam line, which affects the synchronization of response between devices, and solves the problem of existing technology that the response time of wedge-shaped energy reducer is slowed down a lot due to the increase of volume.

Description

Technical Field

[0001] This invention belongs to the technical field of proton therapy systems, and particularly relates to a proton beam energy selective control system. Background Technology

[0002] In proton radiotherapy devices, to apply the proton cyclotron accelerator clinically, an energy-proton selective control system must be used to adjust the energy of the extracted proton beam according to the different depths and thicknesses of the tumor. This proton beam energy selective control system includes: energy degraders, multiple magnets, multiple four-fan collimators, momentum-selective slits, energy-selective slits, motion boards, and system boards, etc., arranged along the path from the beamline starting point (the beam is drawn from the accelerator outlet, passes through a set of quadrupole magnets and guide magnets) to the target point (the rotating gantry connected to the treatment head).

[0003] One of the challenges in implementing a proton energy selective control system using existing technology lies in the long communication time required to send commands to each device in the beamline, which affects the synchronization of responses between devices. Clinically, however, a response time of only 80 milliseconds is required for each energy level change. The reasons for this long communication time and impact on the synchronization of responses are as follows: First, beamline energy control involves controlling the energy of the entire beamline, requiring dozens or even hundreds of devices distributed from the start to the end of the beamline. The stringent requirement is that regardless of the number of devices on the beamline, only when all devices complete the dynamic process of executing the specified actions within the stipulated time can the entire beamline complete energy reduction within the specified time. Second, current proton therapy systems control beamline devices using a parallel command method, but from a microscopic perspective, for transmitting control... The command writing step is still a serial command, and the task switching time is long. For example, the lower-level machine uses the VxWorks real-time operating system instead of the Linux operating system because VxWorks has a shorter task switching time compared to other systems (such as Linux). However, VxWorks still uses an asynchronous startup method for the initialization process of multiple tasks, meaning that the initialization process of the previous task can only begin after the initialization process of the next task is completed. If commands are to be sent to multiple devices on the beamline, the commands need to be sent one by one. When there are a large number of beamline devices to be controlled, the time spent in the communication process increases significantly. The communication time is superimposed on the dynamic response time, making the dynamic response speed slower. At the same time, there is a long time interval between the first and last devices receiving the command, resulting in asynchronous responses between devices.

[0004] The second difficulty in implementing proton energy selective control systems using existing technologies lies in the fact that existing de-energizers cannot simultaneously meet the requirements of fast response speed and avoiding beam energy loss. The first type, the multi-wedge de-energizer, while meeting the energy reduction speed requirement, suffers from significant beam energy loss. This is because the multi-wedge de-energizer uses multiple relatively small (small width and length) wedge-shaped de-energizers arranged side-by-side. Its fast response is achieved through its relatively short length or path, and the side-by-side arrangement meets the de-energizer thickness requirement. Only when the de-energizer thickness meets the requirement can the maximum energy reduction range be achieved. However, because it involves multiple wedge-shaped de-energizers arranged side-by-side with multiple air gaps, energy loss occurs every time the beam passes through an air gap. This results in multiple energy losses when passing through multiple sets of wedge-shaped de-energizers. Another existing technology is the double-wedge airfoil beryllium de-energizer. While this reduces beam loss issues associated with multi-wedge de-energizers, beryllium is toxic and generates a large number of neutrons, increasing the difficulty of radiation protection. Furthermore, although this double-wedge airfoil de-energizer reduces energy loss by converting multiple double-wedge airfoils into a single one, the overall volume increases significantly. Replacing multiple double-wedge airfoils with a single one not only increases the thickness but also the length or travel distance, increasing several times over. This increased length or travel distance leads to a several-fold slower response time. Since the de-energizer is the first device in the proton beam energy selective control system, if the first device's response time is delayed, and the proton therapy system controls the beamline equipment using a serial command method, the delay time of the entire beamline will be even more severe. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by proton beam energy selection systems. The aim is to solve the problems of long communication time when issuing commands to various devices in the beamline, which affects the synchronization of responses between devices, and to solve the problem that the increased size of wedge de-eners in existing technologies results in a length or distance traveled that is several times greater than that of multi-wedge de-eners, leading to a significantly slower de-ener response time.

[0006] To address the problems existing in the prior art, the present invention proposes the following technical solution:

[0007] A proton beam energy selection control system includes a system board, a motion board, an energy depressor, multiple four-pole collimators, and multiple magnets (including quadrupole magnets, guide magnets, and deflection magnets). The system board's input is connected to a treatment head, acquiring the beam energy information required for the current treatment from the treatment head. Its output is connected to the motion board and the magnet power supply, respectively, sending action commands for the energy depressor stepper motors and the four-pole collimator stepper motors to the motion board, and sending magnet power supply parameters to the magnet power supply. The motion board's input is connected to the system board, and its output is connected to the energy depressor and the four-pole collimators. The energy depressor and the four-pole collimators each include an energy depressor assembly, an energy depressor stepper motor driver and an energy depressor stepper motor, a four-pole collimator assembly, and a four-pole collimator stepper motor driver. The device includes a stepper motor for the energy reducer assembly and a stepper motor for the four collimators. The energy reducer assembly and the four collimators assembly have input terminals for the energy reducer stepper motor and the four collimators stepper motor, respectively, and move under the control of these motors. The energy reducer stepper motor driver and the four collimators stepper motor driver have input terminals connected to a motion board and output terminals connected to their respective stepper motors. The magnet includes multiple magnets arranged on the current beamline and a magnet power supply within each magnet. The input terminal of the magnet power supply within each magnet is connected to a system board and obtains magnet power supply parameters corresponding to the current treatment head energy from the system board. The output terminal is connected to the corresponding magnet and controls the magnet's magnetic field (including energy selection slits and momentum selection slits). Its characteristics are:

[0008] The system board is equipped with a VxWorks embedded real-time control system, which enables shorter switching times for each task and timely feedback from external devices.

[0009] The system board and the treatment head communicate via DDS, which saves the handshake time between the two parties.

[0010] The system board includes a multi-task scheduling unit and a table lookup unit; the multi-task scheduling unit is equipped with a synchronous motion command transmission module. When the initialization processes of multiple tasks are started in an asynchronous manner with the first and last tasks connected, the synchronous motion command transmission module enables the asynchronously started multi-task modules to receive scheduling commands at the same time through command transmission.

[0011] The energy selection control system controls the energy reduction response time of each level of the energy reducer to be faster than that of the multi-wedge energy reducer, and can complete the energy switching within 50 milliseconds; the wedge energy reducer includes a pair of wedge-shaped graphite energy reducing plates with tilt angles, the length or distance traveled by the pair of wedge-shaped graphite energy reducing plates with tilt angles is several times the length or distance traveled by the multi-wedge energy reducing plates, and the width is the same as the sum of the widths of the multi-wedge energy reducing plates.

[0012] Furthermore, the lookup module includes a de-energizer lookup submodule, a four-fan collimator lookup submodule, and a magnet power supply lookup submodule. Each of these submodules performs a lookup based on the treatment head beam energy value obtained from the system board, thereby obtaining the number of steps required for the de-energizer stepper motor, the number of steps required for the four-fan collimator stepper motor, and the parameters that need to be adjusted for the magnet power supply, and then sends them to the multi-task scheduling module.

[0013] Furthermore, the multi-task scheduling unit includes an energy reducer task module, a four-fan collimator task module, a magnet power supply task module, and a synchronous motion command transmission module. The energy reducer task module, the four-fan collimator task module, and the magnet power supply task module each include an execution initialization task submodule, a waiting synchronous motion command submodule, and a receiving synchronous motion command submodule. The waiting synchronous motion command submodule suspends its current task after determining that the current initialization task is completed, until it receives the synchronous motion command. Upon receiving the synchronous motion command, the receiving synchronous motion command submodule sends commands to the motion control card via the energy reducer task module, the four-fan collimator task module, and the magnet power supply task module.

[0014] Furthermore, the synchronous motion command transmission module is provided with a waiting suspension submodule and a synchronous command transmission submodule; the waiting suspension submodule waits for the last task to be suspended and then notifies the synchronous command transmission submodule, and the synchronous command transmission submodule sends synchronous motion commands to the energy depressor task module, the four collimator task module, and the magnet power supply task module after receiving the notification.

[0015] Furthermore, the initialization task submodules of the energy degrader task module and the four collimator task module include calling the S-curve algorithm module, which includes setting the S-curve parameters submodule, which includes setting four acceleration parameters and four deceleration parameters; the initialization of the magnet power supply task module includes establishing network communication between the magnet power supply and the system board by establishing a UDP connection.

[0016] Furthermore, the wedge-shaped energy reducer includes a wedge-shaped energy reducer plate, an incident collimator, an exit collimator, an electronic ruler, a stepper motor, a stepper motor driver, and a support frame. The wedge-shaped energy reducer plate is mounted vertically on the support frame at a certain angle. The wedge-shaped energy reducer plate is formed by connecting a pair of wedge-shaped graphite energy reducer plates with an inclination angle via a universal joint and a lead screw, with a gap between the wedge-shaped graphite energy reducer plates. The beam passes through the gap perpendicular to the gap. The incident collimator and the exit collimator are arranged along the beam direction on the support frame on both sides of the wedge-shaped energy reducer plate. On the frame, its height is the height of the beamline center point; the electronic ruler is installed on one side of the wedge-shaped energy reduction plate on the support frame, and reads and displays the displacement of the wedge-shaped energy reduction plate as it moves; the stepper motor is connected to the wedge-shaped energy reduction plate through a cross-slider coupling and a right-hand ball screw, and drives the wedge-shaped energy reduction plate to increase or decrease its thickness; the stepper motor driver's input end is connected to the motion board, and its output end is connected to the stepper motor; the universal joint and lead screw include a right-hand ball screw and a left-hand ball screw, with the universal joint in the middle.

[0017] Furthermore, the pair of wedge-shaped graphite energy reducing sheets with tilt angles, each wedge-shaped graphite energy reducing sheet has a tilt angle of 12°, a thickness of 40 mm, a top corner width of 1 mm, a bottom side width of 100 mm, and a length of 500 mm; the maximum width of the pair of wedge-shaped energy reducing sheets during relative movement is 200 mm, and the minimum width is 6 mm.

[0018] Furthermore, the energy reduction response time for each level of the wedge-shaped energy reduction plate is faster than that for the multi-wedge-shaped energy reduction plate. Specifically, the energy switching time for each level is less than 50ms, which is more than 1.2 times faster than the energy reduction time for each level of the multi-wedge-shaped plate.

[0019] Furthermore, the energy reducer driver and the stepper motor driver are respectively provided with an interface for connecting an external motion board. Through this interface, motion information of the relevant stepper motor can be obtained from the motion board to ensure that the energy switching time is within 50ms each time. This motion information includes the number of steps, motion speed, and motion acceleration that ensure the corresponding time of 50ms.

[0020] Furthermore, the wedge-shaped energy-reducing plate includes a right energy-reducing plate and a left energy-reducing plate; the right energy-reducing plate is connected to the right lead screw nut, which is connected to a right-hand ball screw; the left energy-reducing plate is connected to the left lead screw nut, which is connected to a left-hand ball screw. The stepper motor is connected to a cross-slider coupling, which in turn connects to the right-hand ball screw for rotation. The right-hand ball screw drives the universal joint, which in turn drives the left-hand ball screw to rotate. The left-hand ball screw drives the left energy-reducing plate through the left lead screw nut, thereby enabling the stepper motor to drive the left and right energy-reducing plates to move in opposite directions or in opposite directions.

[0021] Advantages and effects of the present invention

[0022] 1. This invention provides a proton beam energy selective control system that enables the beam energy to be continuously adjustable between 70-240MeV and to rapidly complete the adjustment process of adjacent beam energy within 50ms, thus solving the problem of rapid point scanning in proton therapy and volume repetitive scanning when treating moving target areas.

[0023] 2. This invention fully leverages the advantages of the VxWorks embedded real-time control system, such as its strong real-time performance and shorter task switching times. Simultaneously, it compensates for the shortcomings of existing systems that can only send instructions at the end of each task process, leading to long communication times for instruction delivery to various beamline devices and affecting the synchronization of responses between devices. This invention adds suspension and waiting functions to each task module within the multi-task scheduling unit, ensuring that instructions are not received even when the current process ends, laying the foundation for synchronous instruction reception across multiple tasks. Furthermore, the multi-task scheduling unit adds a synchronous task instruction transmission module, which waits for the last task to be suspended before notifying all multi-task modules of the task instruction. This achieves synchronous instruction reception across multiple beamline tasks, solving the problem of long communication times for instruction delivery to various beamline devices in existing technologies, which affects the synchronization of responses between devices.

[0024] 3. This invention connects the energy degrader stepper motor driver to a motion board, the motion board to a system board, installs a VxWorks embedded real-time control system within the system board, establishes DDS communication between the system board and the treatment head, sets up an energy degrader task module on the system board, sets up an initialization call submodule within the energy degrader task module, and the initialization call submodule calls the S-curve algorithm module. Then, by setting four acceleration parameters, four deceleration parameters, and motion parameters of the S-curve algorithm module, these parameters are transmitted to the energy degrader driver via the motion board. The energy degrader driver then controls the energy degrader stepper motor, ultimately achieving a 50-millisecond energy shifting time for the energy degrader. Although the length or distance traveled by the wedge-shaped energy degrader in this invention is five times that of the multi-wedge energy degrader, the 50-millisecond energy response time is 1.2 times faster than the 60-millisecond time of the multi-wedge energy degrader. Furthermore, by using a pair of wedge-shaped energy degraders instead of the traditional multiple pairs of wedge-shaped energy degraders, the beam scattering problem caused by the beam passing through multiple pairs of wedge-shaped energy degraders is completely solved.

[0025] 4. This invention organically combines DDS communication, a VxWorks embedded real-time control system, and an S-curve algorithm module, solving the problem that existing wedge-shaped energy degraders, due to their increased size, have several times longer lengths or travel distances compared to multi-wedge energy degraders, resulting in significantly slower response times. Using DDS communication saves the handshake time required between communicating parties; employing the VxWorks embedded real-time control system shortens the switching time for each task and ensures timely feedback from external devices; and calling the S-curve algorithm module eliminates concerns about potential damage to the stepper motor due to increased speed and high inertia during rapid 50-millisecond switching of large-volume wedge-shaped energy degraders. Attached Figure Description

[0026] Figure 1 This is a network topology diagram of the proton beam energy selection control system of the present invention;

[0027] Figure 2 This is the functional architecture of the proton beam energy selection control system of the present invention;

[0028] Figure 3 This is a schematic diagram of the lookup table unit of the present invention;

[0029] Figure 4 This is a schematic diagram of the multi-task scheduling unit of the present invention;

[0030] Figure 5-1 This is a flowchart of the multi-task scheduling process of the present invention;

[0031] Figure 5-2 This invention relates to the principle of multi-task scheduling.

[0032] Figure 6 This is a schematic diagram illustrating the speed variation of a stepper motor under the S-curve algorithm.

[0033] Figure 6 During the time interval 0-t1, the stepper motor performs variable acceleration motion, with the acceleration first increasing and then decreasing; during the time interval t1-t2, it moves at a constant speed of v0; during the time interval t2-t3, the stepper motor performs variable deceleration motion, with the deceleration first increasing and then decreasing.

[0034] Figure 7-1 This is a schematic diagram of the energy reducer structure of the present invention;

[0035] Figure 7-2 This is a schematic diagram showing the connection between the left-hand and right-hand ball screws of the energy reducer of the present invention via a universal joint.

[0036] In the diagram: 1: Energy reducer; 1-1: Left energy reducer; 1-2: Right energy reducer; 1-3: Incident collimator; 1-4: Outgoing collimator; 1-5: Linear displacement sensor; 1-6: Pointer and slider; 1-7: Scale; 1-8, 1-9: Slide rail; 1-10: Left-hand ball screw; 1-11: Right-hand ball screw; 1-12: Universal joint; 1-13, 1-14: Limit switch; 1-15: Limit switch contact; 1-16: Cross-slider coupling; 1-17: Stepper motor; 1-18, 1-19: Support frame; 1-20: Stepper motor driver; 2, 4, 5, 7, 8, 9, 10: Magnets; 3, 11: Four-panel collimator; 6: Momentum selection slit; 12: Motion board; 13: System board; 14: Host computer. Detailed Implementation

[0037] Design principle of this invention:

[0038] 1. Design Objectives and Problems Solved by this Invention: Design Objective: To control the total energy switching time of all devices along the beamline from start to finish in 80 milliseconds. Problems Solved: To address two technical bottlenecks that must be solved simultaneously to truly achieve the 80-millisecond energy switching time requirement. One problem is the long communication time for issuing commands to each device in the beamline, affecting the synchronization of responses between devices; the other problem is that using a wedge-shaped de-energizer instead of a multi-wedge de-energizer results in a significantly increased size, making the length or distance traveled by the wedge-shaped de-energizer several times greater than that of the multi-wedge de-energizer, leading to a much slower de-energizer response time. If only one problem, such as communication time, is solved without addressing the relatively long travel distance and slow response time of the wedge-shaped de-energizer, the de-energizer's delay time will still affect the 80-millisecond energy switching performance. If only the de-energizer's time delay is solved without addressing the communication time issue, even if the de-energizer achieves a 50-millisecond switching time, the entire beamline's energy switching response time will still fail to meet the 80-millisecond design requirement because the communication delay of other devices in the beamline remains unresolved.

[0039] 2. Design Principles of Multi-Task Scheduling. Traditional multi-task scheduling methods generally employ asynchronous instruction sending, where the scheduling system sends instructions at the last moment of each task process. Since the duration of each task process varies, sending instructions only at the end of the process results in unequal completion times for the tasks that receive instructions first and last. The task receiving the instruction first may complete first, and the task receiving the instruction last may complete last, thus lengthening the overall task completion time. To address this issue, this invention makes two improvements to the multi-task scheduling unit: First, each task module in the multi-task scheduling unit adds suspension and waiting functions. Once its initialization process is complete, the task is suspended and waits. Because the task is in a suspended state, it will not receive instructions even if the current process ends, laying the foundation for synchronous instruction reception. Second, the multi-task scheduling unit adds a synchronous task instruction transmission module. This module waits for the last task to suspend before notifying all multi-task modules of the task instruction. This achieves synchronous instruction reception for multiple tasks in the bundler.

[0040] Note: The synchronous receiving instruction refers to macroscopic synchronization and microscopic serial execution. Although the synchronous task instruction transmission module waits for the last task to suspend before notifying all multi-task modules of the task instruction, the actual command reception is still performed according to... Figure 5-2 The commands are received in priority queues, but this time is very short and negligible because it's just different team members on the same starting line receiving the commands sequentially. Since they are all on the same starting line, even if there are differences in the time they receive the commands, these differences are negligible. This differs from the traditional method, which sends commands at the very end of each task process. It's like people on different starting lines receiving commands at different finish lines, thus lengthening the total time from start to finish for everyone on different starting lines.

[0041] 3. Energy Degrader Design Principles. 1) Design Challenges of Wedge-Shaped Energy Degraders. The design challenge lies in how to solve the problem of rapid acceleration and deceleration. The danger of rapid acceleration and deceleration is that the equipment is easily damaged when its inertia is high. Rapid acceleration and deceleration refer to the steep acceleration and deceleration of the stepper motor. This invention needs to increase the motor speed to compensate for the energy switching time delay caused by the long distance. However, if the speed is not handled properly, rapid acceleration and deceleration can lead to equipment damage. Traditional multi-wedge-shaped energy degraders do not involve the problem of rapid acceleration and deceleration because they are small in size and light in weight, resulting in low inertia. In this invention, the length of the wedge-shaped energy degrader is 5 times that of the multi-wedge-shaped energy degrader, and the greater weight results in greater inertia. To ensure the stepper motor reaches the set speed while avoiding sudden starts and stops, this invention employs an S-curve approach. Compared to traditional methods, which use a trapezoidal curve for linear acceleration and deceleration without smooth transitions, the S-curve allows for sufficiently high speeds in the middle section (t1 to t2) while maintaining smooth curves on both sides. Using the S-curve ensures the stepper motor reaches the set maximum speed during the constant-speed phase, and smoothly transitions from the lowest point to the highest and vice versa, thus resolving the issue of sudden starts and stops. 2) Solution for the wedge-shaped energy reducer in this invention: Since the energy switching time of the energy reducer is only 50 milliseconds in total, it is not possible to solve the problem from just one aspect, but rather to save time in every aspect. Each aspect must support and work together to ultimately achieve the 50-millisecond switching time. This invention solves the problem of rapid response from three aspects: communication layer, system layer, and scheduling layer. First, the communication layer uses DDS communication, and the system board and treatment head use DDS communication, saving the time wasted on "handshakes". Second, the motion board uses the VxWorks embedded real-time control system, which makes the switching time of each task shorter and allows for timely feedback from external devices. Third, the system board looks up the corresponding 50-millisecond switching parameters of the motor for the current energy, including motor steps and acceleration, and calls the S-curve to achieve a smooth transition from the lowest to the highest acceleration point, and a smooth transition from the highest to the lowest deceleration point.

[0042] Based on the above principles, this invention designs a proton beam energy selection control system, such as... Figure 1 , Figure 2As shown, the system includes a system board 13, a motion board 12, an energy depletor 1, multiple four-fan collimators 3 and 11, and multiple magnets 2, 4, 5, 7, 8, 9, and 10. The multiple magnets include quadrupole magnets, guide magnets, and deflection magnets. The system board 13 has its input connected to the treatment head, obtaining the beam energy information required for the current treatment from the treatment head. Its output is connected to the motion board 12 and the magnet power supplies 2, 4, 5, 7, 8, 9, and 10, respectively. It sends the action commands of the energy depletor stepper motors 1-17 and the four-fan collimators 3 and 11, as well as the stepper motors, to the motion board 12, and sends the magnet power supply parameters to the magnet power supplies 2, 4, 5, 7, 8, 9, and 10. The motion board 12 has its input connected to the system board 13 and its output connected to the energy depletor 1 and the four-fan collimators 3 and 11. The energy depletor 1 and the four-fan collimators 3 and 11 each include an energy depletor assembly and an energy depletor stepper motor driver 1-20. The system includes stepper motors 1-17 for the energy depressor, four collimator assemblies, four collimator stepper motor drivers, and four collimator stepper motors. The energy depressor assembly and the four collimator assembly have their input terminals connected to the stepper motors 1-17 and 1-20 respectively, and move under their control. The stepper motor drivers 1-20 and 1-20 have their input terminals connected to the motion board 12, and their output terminals connected to their respective stepper motors. The magnets include multiple magnets arranged on the current beamline and a magnet power supply within each magnet. The input terminal of each magnet power supply is connected to the system board 13 and obtains the magnet power supply parameters corresponding to the current treatment head energy from the system board 13. The output terminal is connected to the corresponding magnet and controls the magnet magnetic field (including energy selection slits and momentum selection slits). Its characteristics are:

[0043] The system board 13 is equipped with a VxWorks embedded real-time control system, which enables shorter switching times for each task and timely feedback from external devices.

[0044] The system board 13 and the treatment head communicate via DDS, which saves the handshake time between the two parties.

[0045] like Figure 2 As shown, the system board 13 includes a multi-task scheduling unit and a table lookup unit; the multi-task scheduling unit is equipped with a synchronous motion command transmission module. When the initialization processes of multiple tasks are started in an asynchronous manner with the beginning and end connected, the synchronous motion command transmission module enables the asynchronously started multi-task modules to receive scheduling commands at the same time through command transmission.

[0046] The energy selection control system controls the energy reduction response time of each level of the energy reducer to be faster than that of the multi-wedge energy reducer, and can complete the energy switching within 50 milliseconds; the wedge energy reducer includes a pair of wedge-shaped graphite energy reducing plates with tilt angles, the length or distance traveled by the pair of wedge-shaped graphite energy reducing plates with tilt angles is several times the length or distance traveled by the multi-wedge energy reducing plates, and the width is the same as the sum of the widths of the multi-wedge energy reducing plates.

[0047] Supplementary Note 1

[0048] 1. The control system includes a motion board 12, a system board 13, and a host computer. The motion board is used to send pulse commands to the stepper motor; the system board contains an embedded real-time operating system developed based on VxWorks, which is responsible for the main functions of the control unit; the host computer's host program is developed based on QT and is used for debugging and testing.

[0049] 2. System board 13 communicates with the motion board via the VME bus and with the magnet and host computer via the network port.

[0050] 3. The equipment on the beamline controlled by this control system includes: the proton beam energy selection system and all magnets and four collimators extending from it to the rotating gantry connected to the treatment head. The main controlled components are one de-energizer stepper motor, eight stepper motors for the four collimators / momentum selection slits, and 46 magnet power supplies, each with independent control. The momentum selection slit is actually also a four-collimator, but it has a specific name in a specific location and plays a different role on the beamline than a regular collimator.

[0051] The proton beam energy selective control system includes: an energy depressor, magnets, four collimators, and a momentum selective slit. When the control system receives energy information from the treatment head, it simultaneously sends commands to the controlled device to move / adjust to the corresponding position / parameters.

[0052] 4. The embedded real-time operating system has a DDS communication module, a multi-task scheduling unit, and a table lookup unit.

[0053] 5. The DDS communication module is used to establish communication between the system and the treatment head. By binding to the same communication domain as the treatment head, the system acts as a subscriber in the communication domain, continuously listening to the DDS messages sent by the treatment head and extracting the beam energy information contained therein.

[0054] 6. The multi-task scheduling unit is divided into energy reducer task, four-fan collimator task, magnet power supply task, and synchronous motion command transmission task. The energy reducer stepper motor task is used to send relevant commands to the energy reducer stepper motor driver; the four-fan collimator stepper motor task is used to send relevant commands to the four-fan collimator stepper motor driver; the magnet power supply communication task sends current and PID parameter information to various magnets through establishing a UDP connection; and the synchronous motion command transmission task is used to send synchronous motion commands to the energy reducer task, four-fan collimator task, and magnet power supply task.

[0055] 7. The lookup unit uses the beam energy value obtained from the treatment head to look up the table to obtain the number of steps required for the stepper motor of the energy degrader, the number of steps required for the stepper motor of the four collimators, and the parameters that need to be adjusted for the magnet power supply.

[0056] The tables above include a "Energy - Stepper Motor Steps from Energy Degrader" table, a "Energy - Stepper Motor Steps from Four-Fan Collimator" table, and a "Energy - Magnet Power Supply Parameters" table. When the acquired energy value is not in any of the tables, the energy range within the table is determined, and interpolation is performed to calculate the stepper motor steps.

[0057] 8. The task modules in the multi-task scheduling unit are created as tasks. Each controlled device has a corresponding task, which includes: synchronous motion command transmission task, energy reducer task, four collimator tasks (8 in total), and magnet power supply tasks (46 in total).

[0058] 9. The system has a specific scheduling order for the above tasks, and calls the S-curve algorithm in the motion board in the energy degrader task and the four collimator task. By setting the optimal speed / acceleration parameters of the stepper motor, it can ensure that the response time of the energy degrader is within 50ms during each energy switch.

[0059] 10. The multi-task scheduling method of this control system mainly achieves task synchronization through semaphores.

[0060] Scheduling principle: High-priority tasks will be executed first, while low-priority tasks that are currently being executed can only be suspended and wait (stopping halfway through their work) until the high-priority task is completed or suspended before they can continue to execute.

[0061] By setting priorities, the scheduling order of each task is declared: 1. Energy degrader task; 2. Four-fan collimator task; 3. Magnet power supply communication task; 4. Synchronous motion command transmission task.

[0062] 11. Semaphores: First, initialize an empty semaphore. When the semaphore is not released, the task that acquires it will be blocked and suspended until the semaphore is released by another task, at which point the task can continue execution. Multi-task synchronization is achieved by initializing empty depressor semaphores, four collimator semaphores, and magnet power semaphores.

[0063] 12. First, the DDS communication module acquires communication data from the treatment head by listening to the communication domain, and then parses it into beam energy values, which are then passed to the lookup table unit.

[0064] Furthermore, such as Figure 3 As shown, the lookup unit includes a de-energizer lookup submodule, a four-fan collimator lookup submodule, and a magnet power supply lookup submodule. Each of these submodules performs a lookup based on the treatment head beam energy value obtained from the system board, thereby obtaining the number of steps required for the de-energizer stepper motor, the number of steps required for the four-fan collimator stepper motor, and the parameters that need to be adjusted for the magnet power supply, and then sends them to the multi-task scheduling module.

[0065] Furthermore, such as Figure 4 As shown, the multi-task scheduling unit includes an energy reducer task module, a four-fan collimator task module, a magnet power supply task module, and a synchronous motion command transmission module. The energy reducer task module, the four-fan collimator task module, and the magnet power supply task module each include an execution initialization task submodule, a waiting synchronous motion command submodule, and a receiving synchronous motion command submodule. The waiting synchronous motion command submodule suspends its current task after determining that the current initialization task is completed, until it receives the synchronous motion command. Upon receiving the synchronous motion command, the receiving synchronous motion command submodule sends commands to the motion control card via the energy reducer task module, the four-fan collimator task module, and the magnet power supply task module.

[0066] Furthermore, the synchronous motion command transmission module is provided with a waiting suspension submodule and a synchronous command transmission submodule; the waiting suspension submodule waits for the last task to be suspended and then notifies the synchronous command transmission submodule, and the synchronous command transmission submodule sends synchronous motion commands to the energy depressor task module, the four collimator task module, and the magnet power supply task module after receiving the notification.

[0067] Furthermore, such as Figure 6 As shown, the initialization task submodules of the energy degrader task module and the four collimator task module include calling the S-curve algorithm module, which includes setting the S-curve parameters submodule, which includes setting four acceleration parameters and four deceleration parameters; the initialization of the magnet power supply task module includes establishing network communication between the magnet power supply and the system board by establishing a UDP connection.

[0068] Supplementary Note 2:

[0069] 1. The energy degrader task module of the multi-task scheduling unit of the system board sets the parameters of the S-curve algorithm in the motion board, namely the curve parameters, the stepper motor speed, and the acceleration. This causes the speed to initially increase slowly, then rapidly, and then return to a slow increase until the speed reaches the set desired speed. This enables rapid start and stop of the stepper motor, which helps to minimize sudden acceleration changes and reduce the impact of rotational inertia caused by the large-volume energy degrader.

[0070] 2. For example Figure 6 As shown, the S-curve parameters are defined as follows: the curve is divided into 9 segments, and the percentage of the area enclosed by the lower half of the curve within the rectangle formed by the two endpoints of each segment is used as the parameter. The data obtained from segments 1, 2, 3, 4, 6, 7, 8, and 9 are the curve parameters.

[0071] Parameter calculation method: Using the S-curve algorithm function, the corresponding curve is plotted using MATLAB, and the corresponding area percentage is calculated.

[0072] The motion time of the stepper motor was obtained by repeatedly testing the pulse signal sent by the motion drive card. Finally, the optimal speed-acceleration combination was selected to achieve rapid control of the stepper motor of the energy degrader.

[0073] Furthermore, such as Figure 7-1 , 7-2As shown, the wedge-shaped energy reducer includes a pair of wedge-shaped energy reducers, an incident collimator 1-3, an exit collimator 1-4, an electronic ruler 1-5, a stepper motor 1-17, a stepper motor driver 1-20, and a support frame 1-19. The wedge-shaped energy reducers are mounted vertically at a certain angle on the support frame 1-19. Each pair of wedge-shaped energy reducers is formed by connecting a pair of angled wedge-shaped graphite energy reducers via a universal joint and a lead screw, with a gap between the wedge-shaped graphite energy reducers. The beam passes through this gap. The incident collimator 1-3 and the exit collimator 1-4 are arranged along the beam direction on the support frame on both sides of the wedge-shaped energy reducers. The height is the height of the beamline center point; the electronic ruler 1-5 is arranged on one side of the wedge-shaped energy reduction plate on the support frame 1-19, and reads and displays the displacement of the wedge-shaped energy reduction plate as it moves; the stepper motor 1-17 is connected to the right energy reduction plate 1-2 through the cross-slider coupling 1-16 and the right-hand ball screw 1-11, and drives the wedge-shaped energy reduction plate to increase or decrease its thickness; the stepper motor driver 1-20 is connected to the motion board 12 at the input end and to the stepper motor 1-16 at the output end; the universal joint and the lead screw include the right-hand ball screw 1-11 and the left-hand ball screw 1-10, with the universal joint in the middle.

[0074] Furthermore, the pair of wedge-shaped graphite energy reducing sheets with tilt angles, each wedge-shaped graphite energy reducing sheet has a tilt angle of 12°, a thickness of 40 mm, a top corner width of 1 mm, a bottom side width of 100 mm, and a length of 500 mm; the maximum width of the pair of wedge-shaped energy reducing sheets during relative movement is 200 mm, and the minimum width is 6 mm.

[0075] Furthermore, the energy reduction response time for each level of the wedge-shaped energy reduction plate is faster than that for the multi-wedge-shaped energy reduction plate. Specifically, the energy switching time for each level is less than 50ms, which is more than 1.2 times faster than the energy reduction time for each level of the multi-wedge-shaped plate.

[0076] Furthermore, the energy reducer driver 1-20 and the stepper motor driver are respectively provided with an interface for connecting an external motion board. Through this interface, motion information of the relevant stepper motor can be obtained from the motion board to ensure that the energy switching time is within 50ms each time. This motion information includes the number of steps, motion speed, and motion acceleration that ensure the corresponding time of 50ms.

[0077] Furthermore, such as Figure 7-1As shown, the wedge-shaped energy reducing plate includes a right energy reducing plate 1-2 and a left energy reducing plate 1-1; the right energy reducing plate 1-2 is connected to the right lead screw nut 1-21, which is connected to the right-hand ball screw 1-11; the left energy reducing plate is connected to the left lead screw nut 1-22, which is connected to the left-hand ball screw 1-10. The stepper motor 1-17 is connected to the cross-slider coupling 1-16, which in turn connects to the right-hand ball screw 1-11 for rotation. The right-hand ball screw 1-11 drives the universal joint, which in turn drives the left-hand ball screw 1-10 for rotation. The left-hand ball screw 1-10 drives the left energy reducing plate 1-1 through the left lead screw nut 1-22, thereby enabling the stepper motor to drive the left and right energy reducing plates to move in opposite directions or away from each other.

[0078] Based on the above-mentioned proton beam energy selective control system, this invention designs a multi-task scheduling method, such as... Figure 5-1 As shown, it includes the following steps:

[0079] Step 1: The multi-task scheduling unit of the system board receives the lookup result data from the lookup unit;

[0080] Step 2: The energy degrader performs the initialization task and begins the initialization process until it is completed;

[0081] Step 3: The energy degrader task is suspended and waits for the synchronization motion command until it is received;

[0082] Step 4: The four collimators perform initialization tasks and begin initialization until the initialization process is complete;

[0083] Step 5: The four collimators are suspended and await the synchronization motion command until it is received;

[0084] Step Six: The magnet power supply performs initialization tasks and begins initialization actions until the initialization actions are completed;

[0085] Step 7: The magnet power supply task is suspended and waits for the synchronization motion command until it is received;

[0086] Step 8: The synchronous motion command transmission module sends the synchronous motion command transmission.

[0087] Step 9: The energy degrader task module sends instructions to the motion board.

[0088] Step 10: The four collimator task module sends instructions to the motion board.

[0089] Step 11: The magnet power supply task module sends instructions to the magnet power supply.

[0090] Supplementary Note 3:

[0091] The sending instructions are actually the parameters required for each task. The tasks of the de-energizer and collimator require the number of steps, and the power supply requires the power parameters.

[0092] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A proton beam energy selection control system, comprising a system board, a motion board, an energy depletor, multiple four-pole collimators, and multiple magnets, wherein the multiple magnets include quadrupole magnets, guide magnets, and deflection magnets; the system board's input terminal is connected to a treatment head, acquiring beam energy information required for the current treatment from the treatment head, and its output terminal is connected to the motion board and the magnet power supply respectively, sending action commands of the energy depletor stepper motor and the four-pole collimator stepper motors to the motion board, and sending magnet power supply parameters to the magnet power supply; the motion board's input terminal is connected to the system board, and its output terminal is connected to the energy depletor and the four-pole collimators; the energy depletor includes an energy depletor assembly, an energy depletor stepper motor driver, and an energy depletor stepper motor; the four-pole collimator stepper motor... The collimator includes a four-fan collimator assembly, a four-fan collimator stepper motor driver, and a four-fan collimator stepper motor; the input terminals of the energy depressor assembly and the four-fan collimator assembly are respectively controlled by the corresponding stepper motors; the input terminals of the energy depressor stepper motor driver and the four-fan collimator stepper motor driver are respectively connected to the motion board, and the output terminals are connected to their respective stepper motors; the magnet includes multiple magnets arranged on the current beamline and a magnet power supply in each magnet, the input terminal of the magnet power supply in each magnet is respectively connected to the system board and obtains the magnet power supply parameters corresponding to the current treatment head energy from it, and the output terminal is connected to the corresponding magnet and controls the magnet magnetic field, characterized in that: The system board is equipped with a VxWorks embedded real-time control system, which enables shorter switching times for each task and timely feedback from external devices. The system board and the treatment head communicate via DDS, saving the handshake time between the two parties. The system board includes a multi-task scheduling unit and a table lookup unit. The multi-task scheduling unit is equipped with a synchronous motion command transmission module, an energy reducer task module, and a four-fan collimator task module. When the initialization processes of multiple tasks are started asynchronously in a head-to-tail manner, the synchronous motion command transmission module enables the asynchronously started multi-task modules to receive scheduling commands at the same time through command transmission. The initialization task sub-modules of the energy reducer task module and the four-fan collimator task module include an S-curve algorithm module, and the S-curve algorithm module includes an S-curve parameter sub-module. The energy selection control system controls the energy degrader to complete energy switching within 50 milliseconds; the wedge-shaped energy degrader includes a pair of wedge-shaped graphite degrading sheets, each wedge-shaped graphite degrading sheet has an inclination angle of 12°, a thickness of 40mm, a top corner width of 1mm, a bottom side width of 100mm, and a length of 500mm.

2. The proton beam energy selective control system according to claim 1, characterized in that: The lookup unit includes a de-ener lookup submodule, a four-fan collimator lookup submodule, and a magnet power supply lookup submodule. Each of these submodules performs a lookup based on the treatment head beam energy value obtained from the system board, thereby obtaining the number of steps required for the de-ener stepper motor, the number of steps required for the four-fan collimator stepper motor, and the parameters that need to be adjusted for the magnet power supply, and then sends them to the synchronous motion command transmission task module in the multi-task scheduling unit.

3. The proton beam energy selective control system according to claim 1, characterized in that: The multi-task scheduling unit also includes a magnet power supply task module; the energy reducer task module, the four-fan collimator task module, and the magnet power supply task module each include an execution initialization task submodule, a waiting synchronization motion command submodule, and a receiving synchronization motion command submodule; the waiting synchronization motion command submodule suspends its current task after determining that the current initialization task is completed, until it receives the synchronization motion command; after receiving the synchronization motion command, the receiving synchronization motion command submodule sends a command to the motion control card, the four-fan collimator task module sends a command to the motion control card, and the magnet power supply task module sends a command to the magnet power supply.

4. The proton beam energy selective control system according to claim 3, characterized in that: The synchronous motion command transmission module includes a waiting suspension submodule and a synchronous command transmission submodule. The waiting suspension submodule waits for the last task to be suspended and then notifies the synchronous command transmission submodule. After receiving the notification, the synchronous command transmission submodule sends synchronous motion commands to the energy degrader task module, the four collimators task module, and the magnet power supply task module.

5. The proton beam energy selective control system according to claim 3, characterized in that: The S-curve parameter submodule is used to set four acceleration parameters and four deceleration parameters; The initialization of the magnet power supply task module includes establishing network communication between the magnet power supply and the system board by establishing a UDP connection.

6. The proton beam energy selective control system according to claim 1, characterized in that: The wedge-shaped energy reducer includes a wedge-shaped energy reducer plate, an incident collimator, an exit collimator, an electronic ruler, a stepper motor, a stepper motor driver, and a support frame. The wedge-shaped energy reducer plate is mounted vertically on the support frame at a certain angle. Each wedge-shaped energy reducer plate is formed by connecting a pair of angled wedge-shaped graphite energy reducer plates via a universal joint and a lead screw, with a gap between the wedge-shaped graphite energy reducer plates. The beam passes through this gap. The incident collimator and the exit collimator are arranged along the beam direction on the support frame on both sides of the wedge-shaped energy reducer plate. The height of the beamline center point is the height of the beamline center point. The electronic ruler is installed on one side of the wedge-shaped energy reduction plate on the support frame. As the wedge-shaped energy reduction plate moves, the displacement of the wedge-shaped energy reduction plate is read and displayed. The stepper motor is connected to the wedge-shaped energy reduction plate through a cross-slider coupling and a right-hand ball screw, and drives the wedge-shaped energy reduction plate to increase or decrease its thickness. The input end of the stepper motor driver is connected to the motion control board, and the output end is connected to the stepper motor. The screw includes a right-hand ball screw and a left-hand ball screw, with a universal joint in the middle.

7. The proton beam energy selective control system according to claim 1, characterized in that: The maximum width of the pair of wedge-shaped energy degraders during relative motion is 200 mm, and the minimum width is 6 mm.

8. The proton beam energy selective control system according to claim 1, characterized in that: The stepper electrode driver for the energy reducer and the stepper motor driver for the four collimators are each provided with an interface for an external motion board. Through this interface, motion information of the relevant stepper motors can be obtained from the motion board to ensure that the energy switching time is within 50ms each time. This motion information includes the number of steps, motion speed, and motion acceleration that ensure the corresponding time of 50ms.

9. A proton beam energy selective control system according to claim 1, characterized in that... The wedge-shaped energy reducer includes wedge-shaped energy reducers, each comprising a right energy reducer and a left energy reducer. The right energy reducer is connected to a right lead screw nut, which in turn connects to a right-hand ball screw. The left energy reducer is connected to a left lead screw nut, which in turn connects to a left-hand ball screw. The stepper motor is connected to a cross-slider coupling, which in turn connects to the right-hand ball screw for rotation. The right-hand ball screw drives a universal joint, which in turn drives the left-hand ball screw for rotation. The left-hand ball screw, through the left lead screw nut, drives the left energy reducer to move, thus enabling the stepper motor to drive the left and right energy reducers to move in opposite directions or in opposite directions.

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