A beam profile probe data processing system and method

Abstract

This invention provides a data processing system and method based on a beam profiler. The system includes a beam profiler detection device, a current-to-voltage converter, an analog-to-digital converter, a low-pass filter, and a computing device. The beam profiler detection device includes a beam profiler, a vacuum chamber, and a beam blocker. The beam profiler is housed in the vacuum chamber and connected to the beam blocker. The output terminal of the beam profiler is connected to the input terminal of the current-to-voltage converter. The analog-to-digital converter is electrically connected to the current-to-voltage converter. The low-pass filter is electrically connected to the analog-to-digital converter. The low-pass filter filters out high-frequency signals from a first digital signal to form a second digital signal. The computing device receives the second digital signal output by the low-pass filter and calculates the beam size information based on the second digital signal. The data processing system and method based on the beam profiler of this invention can improve the measurement accuracy of beam-related dimensions.

Description

Technical Field

[0001] This invention relates to the fields of proton therapy and electronics data processing, and in particular to a data processing system and method based on a beam profiler detector. Background Technology

[0002] The beam size can be adjusted by changing the quadrupole parameters. The beam size needs to be controlled at multiple locations along the beam transmission line to avoid the beam hitting the tube wall and causing damage. Furthermore, measuring the beam size (σ) is crucial for physicists in calculating the beam emittance (ε).

[0003]

[0004] For the C230 proton therapy system, the beam drawn from the accelerator travels through a beam transmission line to the treatment head system. Numerous beam profilers are distributed along the beam transmission line to measure the beam's position, size, and other information during transmission. This allows the control system to adjust the accelerator equipment parameters on the transmission line in real time, thus constraining the beam trajectory. Traditional beam profilers for proton beams include fluorescence targets, IPMs (Ion Profile Monitors), BIFs (Beam Induced Fluorescence), multi-wire detectors, and single-wire detectors, among others.

[0005] For fluorescent targets, the processing results of beam profile measurement data are affected by many factors, such as the observation angle of the target plane, the material and thickness of the fluorescent target, and the focusing of the plane. Furthermore, inappropriate exposure time or range settings can lead to saturation, affecting the accuracy of position and size calculations. IPM-MCP detectors can achieve a measurement resolution of 0.1 mm, but their complex design and high cost make them unsuitable for multiple setups on beam transmission lines. Single-wire detectors have resolution related to the wire width, achieving a position resolution of 0.01 mm, but their slow scanning speed makes them unsuitable for rapid readout of beam position and size. Multi-wire detector readout electronics systems typically have a beam position resolution of less than 1 mm. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a beam profiler-based data processing system and method to solve the problem that the prior art cannot accurately measure beam-related dimensional information. The main improvements are to the data processing system by adding a beam profiler located in a vacuum chamber, using a PCB board instead of a multi-wire structure to avoid problems such as wire loosening and breakage caused by excessive beam intensity, and connecting a beam blocker to each beam profiler to absorb secondary particles and residual gas, which can effectively avoid unnecessary beam loss and secondary particle effects caused by beam tube wall. At the same time, setting an infinite impulse response (IIR) low-pass filter after the analog-to-digital converter can improve the efficiency of electronic development and filter out high-frequency signals in the digital signal.

[0007] This invention provides a data processing system based on a beam profiler, comprising: A beam profile detection device, comprising a beam profile detector, a vacuum box, and a beam blocker, wherein the beam profile detector is disposed in the vacuum box and is connected to the beam blocker; A current-to-voltage converter is provided, wherein the output terminal of the beam profiler is electrically connected to the input terminal of the current-to-voltage converter, and the beam profiler transmits a current signal to the current-to-voltage converter. An analog-to-digital converter (ADC) is provided, comprising an analog-to-digital converter electrically connected to a current-to-voltage converter, wherein the current-to-voltage converter supplies a voltage signal to the ADC. A low-pass filter device includes an infinite impulse response filter, which is electrically connected to the analog-to-digital converter. The analog-to-digital converter sends a first digital signal to the low-pass filter device, and the low-pass filter device filters out high-frequency signals from the first digital signal and outputs a second digital signal. A computing device that receives the second digital signal output by the low-pass filter and calculates beam size information based on the digital signal.

[0008] In one embodiment of the present invention, the vacuum box is a segmented air ionization chamber, and the beam blocker is disposed inside the vacuum box. The beam blocker absorbs secondary particles and residual gas scattered by the beam profile detector.

[0009] In one embodiment of the present invention, the electrode plate of the segmented air ionization chamber is made of two circuit boards with printed copper strips, each circuit board having a plurality of copper strips of a preset size printed on it, the copper strips being arranged at intervals.

[0010] In one embodiment of the present invention, the analog-to-digital converter further includes an integrator located at the input terminal of the analog-to-digital converter, which accumulates the voltage signal and transmits it to the analog-to-digital converter.

[0011] In one embodiment of the present invention, the current-to-voltage device includes a resistor R with an adjustable resistance value.

[0012] In one embodiment of the present invention, the infinite impulse response filter is a direct type II filter with second-order nodes, wherein the order is 4 and the number of nodes is 2.

[0013] In one embodiment of the present invention, the transfer function of the infinite impulse response filter is H, and satisfies the following equation:

[0014]

[0015]

[0016] in, , Let H be a fraction of H, and Z be a constant.

[0017] In one embodiment of the present invention, the position of the copper strip on the circuit board is X. i After digital signal processing, the voltage output value of the channel of the infinite impulse response filter corresponding to the copper strip is W. i Then the position (P) and size ( ) of the beam Satisfies the equation:

[0018]

[0019] A data processing method based on a beam profiler includes: S1: The beam is fed into the beam profile detector inside the vacuum box, and a current signal is output to the current-to-voltage converter. S2: The current-to-voltage device converts the current signal into a voltage signal that can measure the current signal with maximum accuracy, and accumulates the voltage signal through an integrator before outputting it to the analog-to-digital converter; S3: The analog-to-digital converter converts the voltage signal into a digital signal and outputs it to the low-pass filter. The low-pass filter filters out the high-frequency signals in the digital signal and outputs them to the computing module. S4: The calculation module calculates the beam size information based on the output signal of the low-pass filter.

[0020] In one embodiment of the present invention, the low-pass filter is an infinite impulse response filter, which is a direct type II filter with second-order sections, wherein the order is 4 and the number of sections is 2.

[0021] This invention provides a data processing system and method based on a beam profiler. The main improvement is in the data processing system, which employs a beam profiler with a PCB board instead of the multi-wire structure used in traditional technology. This effectively solves the problem of wire breakage caused by excessively high beam current. Simultaneously, a beam blocker connected to the beam profiler is installed inside the vacuum chamber, which can absorb secondary particles and residual gas. Furthermore, an infinite impulse response (IIR) low-pass filter is installed after the analog-to-digital converter, which improves the efficiency of electronics development and filters out high-frequency signals in the digital signal. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system architecture diagram of the data processing system of the present invention; Figure 2 This is a schematic diagram illustrating the working principle of the data processing system of the present invention; Figure 3 A schematic diagram of the waveform of the output signal of an FIR filter used in existing technology; Figure 4 This is a schematic diagram of the waveform of the output signal of the IIR filter used in this invention; Figure 5 This is a flowchart of the data processing method of the present invention. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of this invention is for describing specific implementations and not for limiting the scope of protection of this invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0026] Please see Figures 1 to 5 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness or purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0027] This invention provides a data processing system and method based on a beam profiler. The main improvements are to the data processing system by adding a beam profiler located within a vacuum chamber, using a PCB board instead of a multi-wire structure to avoid problems such as wire breakage due to excessive beam current, and connecting a beam blocker to each beam profiler to absorb secondary particles and residual gas, effectively preventing unnecessary beam losses caused by secondary particle effects on the beam tube wall. Simultaneously, an infinite impulse response (IIR) low-pass filter is placed after the analog-to-digital converter to improve electronics development efficiency and filter out high-frequency signals in the digital signal. Specifically, the data processing system based on the beam profiler of this invention includes a beam profiler detection device, a current-to-voltage converter, an analog-to-digital converter, a low-pass filter, and a computing device. The beam profile detection device includes a beam profile detector, a vacuum chamber, and a beam blocker. The beam profile detector is housed in the vacuum chamber and connected to the beam blocker. The output terminal of the beam profile detector is electrically connected to the input terminal of a current-to-voltage converter, and the beam profile detector supplies a current signal to the current-to-voltage converter. An analog-to-digital converter (ADC) is electrically connected to the current-to-voltage converter, and the current-to-voltage signal supplies a voltage signal to the ADC. A low-pass filter includes an infinite impulse response (IRT) filter, which is electrically connected to the ADC. The ADC supplies a first digital signal to the low-pass filter, which filters out high-frequency signals from the first digital signal and outputs a second digital signal. A computing device receives the second digital signal output by the low-pass filter and calculates the beam size information based on the second digital signal.

[0028] The beam size can be adjusted by changing the quadrupole iron parameter. The beam size needs to be controlled at multiple locations on the beam transmission line to avoid the beam hitting the tube wall and causing damage. Furthermore, measuring the beam size (σ) plays a crucial role in physicists' calculation of beam emittance (ε). For the C230 proton therapy system, the beam drawn from the accelerator reaches the treatment head system via the beam transmission line. Numerous beam profilers are distributed along the beam transmission line to measure the beam's position, size, and other information during transmission, allowing the control system to adjust the accelerator equipment parameters on the transmission line in real time, thus constraining the beam trajectory. Traditional beam profilers for proton beams include fluorescent targets, IPMs (Ion Profile Monitors), BIFs (Beam Induced Fluorescence), multi-wire detectors, and single-wire detectors. The data processing system and method based on beam profilers provided in this invention utilizes a novel detection device designed based on beam profilers. The beam detector operates within a vacuum chamber, as detailed below.

[0029] like Figure 1 and 2 As shown, the data processing system based on a beam profiler provided by this invention includes a beam profiler device, a current-to-voltage converter, an analog-to-digital converter, a low-pass filter, and a computing device. The beam profiler device comprises a beam profiler (BPM), a beam blocker, and a vacuum chamber. The beam profiler is housed within the vacuum chamber. In one embodiment of this invention, the vacuum chamber is a segmented air ionization chamber with a diameter of 70 mm and a thickness of 2.4 mm. The electrodes of this segmented air ionization chamber are made of two printed copper strip circuit boards (PCBs). The front and rear PCBs are used to measure the beam position and dimensional parameters in the X and Y directions, respectively. Each PCB has 16 printed copper strips, with the center strip being 1.5 mm thick and the edge strips being 3.5 mm thick, with a spacing of 0.5 mm between the strips. In this invention, the beam profile detection device uses a PCB board instead of a multi-wire structure, avoiding problems such as wire loosening and breakage due to excessive beam intensity. The structure is simple and can quickly read the position results. By reading the strip position information on the PCB board and combining it with the system output value, relevant information about the beam size can be calculated. Simultaneously, each beam profile detector is connected to a beam blocker, which absorbs scattered secondary particles and residual gas, thereby avoiding unnecessary beam loss and secondary particle effects on the beam tube wall, which could affect the vacuum level and other issues in the vacuum pipe. In the aforementioned embodiment, the BPM beam position measurement resolution is required to be less than 0.5 mm. Therefore, the traditional readout electronics data processing accuracy cannot meet the requirements of the intrinsic quantum therapy system. Therefore, this invention makes the following design for the subsequent system.

[0030] Furthermore, after collecting the beam signal on the beam transmission line, the beam profiler converts the processed beam signal into a current signal. This current signal is then transmitted from the output of the beam detector to a current-to-voltage converter, which converts the received current signal into a voltage signal. In this embodiment, the current-to-voltage converter is equipped with a resistor R that automatically matches a suitable resistance value based on the collected current signal. By changing the resistance value, the converted voltage signal can measure the current signal with maximum accuracy. The current-to-voltage converter then transmits the converted voltage signal to an analog-to-digital converter (ADC), which includes an integrator and an ADC. The converted voltage signal is first accumulated in the integrator, and then the accumulated voltage signal is transmitted to the ADC to be converted into a digital signal. Since the signal acquisition process may be affected by power frequency noise or other high-frequency interference signals, a low-pass filter is provided after the ADC to filter out high-frequency interference in the digital signal in order to improve the accuracy of the measurement results.

[0031] like Figure 2The diagram illustrates the working principle of the beam profiler-based data processing system provided by this invention. The beam profiler (BPM) is located inside a vacuum chamber on the beam transmission line. Under the influence of the vacuum chamber, the BPM receives the beam signal and converts it into a current signal. This current signal contains information such as the beam's position and size, but this information cannot be directly obtained. Therefore, in this embodiment, the current signal output by the BPM is sent to a current-to-voltage converter (IVConverter) for conversion. After entering the IVConverter, the current signal automatically matches a suitable resistor R based on the magnitude of the collected current signal, ensuring that the converted voltage signal can measure the current signal with maximum accuracy. After conversion by the IVConverter, the current signal becomes a voltage signal. To improve the accuracy of data processing, the analog signal needs to be converted into a digital signal. Therefore, before being sent to the analog-to-digital converter (ADC), the voltage signal first passes through an integrator, then through an analog multiplexer to integrate multiple voltage signals, and finally enters the ADC. After entering the ADC, the voltage signal becomes a corresponding first digital signal. However, in several embodiments, it was found that the first digital signal contained a significant amount of high-frequency noise, which affected the final calculation result. Therefore, a low-pass filter was added after the analog-to-digital converter to remove the high-frequency noise from the first digital signal, forming a second digital signal. Finally, the second digital signal was sent to the computing device for postprocessing. The selection of the low-pass filter and the data processing method are described below.

[0032] In this invention, an infinite impulse response (FIR) filter is selected as the low-pass filter. This filter is a direct type II, second-order, two-stage filter with an order of 4 and a stage number of 2. In this embodiment, the ADC sampling rate of the BPM electronics digital signal processing board is 25Ksps, and the filter design should primarily consider filtering out 50Hz power frequency noise. If a finite impulse response (FIR) filter is used, with a passband of 5Hz, a stopband of 50Hz, and a stopband attenuation of 60dB, the order of the FIR low-pass filter would be 1097. Figure 3 As shown, such high-order FIR filters can cause problems in FPGA development, such as long filter parameter loading time, long group delay of the output signal, and long FPGA compilation time, thus affecting development efficiency.

[0033] To address these issues, this invention proposes using an infinite impulse response (IIR) filter, the waveform of which is shown below. Figure 4As shown, IIR filters have higher efficiency and can achieve similar frequency response effects with fewer orders. In this signal processing, all channels use IIR filters with the same parameters, consistent group delay, and no linear phase requirements; therefore, this IIR filter meets the design requirements. The transfer function H of the infinite impulse response filter is as follows:

[0034]

[0035]

[0036] in, , Let H be a fraction of H, and Z be a constant.

[0037] After being filtered by a low-pass filter, the digital signal is sent to a computing device for data processing. Let the position of the copper strip on the circuit board be X. i After digital signal processing, the voltage output of the channel of the infinite impulse response filter corresponding to the copper strip is W. i Then the position (P) and size ( ) of the beam Satisfies the equation:

[0038]

[0039] This allows us to obtain relevant beam size information, with a resolution of less than 0.5 mm.

[0040] This invention also provides a beam profiler-based data processing method, comprising four steps: S1: The beam is introduced into the beam profiler inside the vacuum chamber, and a current signal is output to a current-to-voltage converter; S2: The current-to-voltage converter converts the current signal into a voltage signal that can measure the current signal with maximum accuracy, and accumulates the voltage signal through an integrator before outputting it to an analog-to-digital converter; S3: The analog-to-digital converter converts the voltage signal into a digital signal and outputs it to a low-pass filter, which filters out high-frequency signals in the digital signal and outputs it to a calculation module; S4: The calculation module calculates the beam size information based on the output signal from the low-pass filter.

[0041] like Figure 5As shown, in S1, the beam signal is transmitted to the beam profiler via the beam transmission line and processed by the beam profiler, then converted into a current signal. Simultaneously, secondary particles and residual gas generated during the conversion process are absorbed by the beam blocker, ensuring the vacuum level of the vacuum pipe. In S2, the converted current signal is sent to a current-to-voltage converter for further conversion. In this embodiment, the current-to-voltage converter is equipped with a resistor R that automatically matches a suitable resistance value based on the collected current signal. By changing the resistance value, the converted voltage signal can measure the current signal with maximum accuracy. In S3, the current-to-voltage converter sends the converted voltage signal to an analog-to-digital converter (ADC), which includes an integrator and an ADC. The converted voltage signal is first accumulated in the integrator, and then the accumulated voltage signal is sent to the ADC to be converted into a digital signal. However, the newly converted digital signal has significant high-frequency interference. Therefore, in this invention, a low-pass filter is provided after the ADC to filter out high-frequency interference in the digital signal. Finally, in S4, after being filtered by a low-pass filter, the digital signal is sent to the computing device for digital processing. Let the position of the copper strip on the circuit board be X. i After digital signal processing, the voltage output of the channel of the infinite impulse response filter corresponding to the copper strip is W. i Then the position (P) and size ( ) of the beam Satisfies the equation:

[0042]

[0043] This invention proposes a data processing system based on a beam profiler. The main improvements include adding a beam profiler located within a vacuum chamber, using a PCB board instead of a multi-wire structure to avoid problems such as wire breakage due to excessive beam current, and connecting a beam blocker to each beam profiler to absorb secondary particles and residual gas, effectively preventing unnecessary beam losses and secondary particle effects caused by beam tube wall defects. Furthermore, an infinite impulse response low-pass filter is placed after the analog-to-digital converter to improve electronics development efficiency and filter out high-frequency signals in the digital signal.

[0044] Therefore, the data processing system based on a beam profile detector of the present invention can solve the problem of low accuracy in beam-related dimension measurement.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A data processing system based on a beam profiler, characterized in that, include: A beam profile detection device, comprising a beam profile detector, a vacuum box, and a beam blocker, wherein the beam profile detector is disposed in the vacuum box and is connected to the beam blocker; A current-to-voltage converter is provided, wherein the output terminal of the beam profiler is electrically connected to the input terminal of the current-to-voltage converter, and the beam profiler transmits a current signal to the current-to-voltage converter. An analog-to-digital converter (ADC) is provided, comprising an analog-to-digital converter electrically connected to a current-to-voltage converter, wherein the current-to-voltage converter supplies a voltage signal to the ADC. A low-pass filter device includes an infinite impulse response filter, which is electrically connected to the analog-to-digital converter. The analog-to-digital converter sends a first digital signal to the low-pass filter device, and the low-pass filter device filters out high-frequency signals from the first digital signal and outputs a second digital signal. A computing device that receives the second digital signal output by the low-pass filter and calculates beam size information based on the digital signal; The vacuum box is a segmented air ionization chamber. The electrode plates of the segmented air ionization chamber are made of two printed copper strip circuit boards, and the two circuit boards are used to measure the beam position and size parameters in the X and Y directions, respectively. The circuit board is printed with several copper strips of a preset size, and the copper strips are arranged at intervals. The beam blocker is located inside the vacuum box and absorbs secondary particles and residual gas scattered by the beam profile detector.

2. The data processing system based on a beam profiler according to claim 1, characterized in that, The analog-to-digital converter also includes an integrator, which is located at the input of the analog-to-digital converter and accumulates the voltage signal and sends it to the analog-to-digital converter.

3. The data processing system based on a beam profiler according to claim 1, characterized in that, The current-to-voltage converter includes an adjustable resistor R.

4. The data processing system for the beam profiler according to claim 1, characterized in that, The infinite impulse response filter is a direct type II, second-order, with an order of 4 and a number of sections of 2.

5. The data processing system for the beam profiler according to claim 1, characterized in that, The transfer function of the infinite impulse response filter is H, and it satisfies the following equation: in, , Let H be a fractional function of H, and Z be a constant.

6. The data processing system for the beam profiler according to claim 5, characterized in that, The position of the copper strip on the circuit board is X. i After digital signal processing, the voltage output value of the channel of the infinite impulse response filter corresponding to the copper strip is W. i Then the position (P) and size ( ) of the beam Satisfies the equation: 。 7. A data processing method based on a beam profiler, characterized in that, The method, applied to the data processing system according to any one of claims 1 to 6, comprises: S1: The beam is fed into the beam profile detector inside the vacuum box, and a current signal is output to the current-to-voltage converter. S2: The current-to-voltage device converts the current signal into a voltage signal that can measure the current signal with maximum accuracy, and accumulates the voltage signal through an integrator before outputting it to the analog-to-digital converter; S3: The analog-to-digital converter converts the voltage signal into a digital signal and outputs it to the low-pass filter. The low-pass filter filters out the high-frequency signals in the digital signal and outputs them to the computing module. S4: The calculation module calculates the beam size information based on the output signal of the low-pass filter.

8. The data processing method based on a beam profiler according to claim 7, characterized in that, The low-pass filter is an infinite impulse response filter, which is a direct type II filter with two sections, having an order of 4 and two sections.

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