Proton beam spot position measuring and verifying device

Abstract

The invention discloses a proton beam spot position measurement and verification device which is electrically connected with a control module and comprises a detection module which is fixed on a hollow rotating disc through a supporting structure and comprises a detector used for receiving photoelectric signals generated by proton beam irradiation; the hollow rotating disc is fixed to the rotating module, a driving mechanism I used for driving the hollow rotating disc to rotate is arranged at the top end of the rotating module, a hollow cylindrical mold body is embedded into a round hole in the center of the rotating module, a long rod is inserted into an inner hole of the cylindrical mold body, and a tungsten bead is embedded into the free end of the long rod. And the three-dimensional motion module comprises motion mechanisms in X, Y and Z directions which are sequentially arranged from top to bottom. Therefore, the position can be adjusted autonomously through the three-dimensional motion module without relying on a treatment bed; meanwhile, the modules are high in integration level, the overall size is reduced, and cost is reduced; the detector is low in cost and high in resolution, and improves the measurement precision.

Description

Technical Field

[0001] This invention relates to the field of medical auxiliary device application technology, and in particular to a proton beam spot position measurement and verification device. Background Technology

[0002] Proton therapy is one of the most advanced radiotherapy methods in the world today. Compared with conventional radiotherapy, its unique Bragg peak advantage is more conducive to protecting normal organs and reducing the rate of adverse reactions in patients. Pencil beam scanning technology is the most advanced technique in proton therapy, which has extremely high requirements for the accuracy of treatment positioning. It is necessary to ensure that the deviation between the image guidance center and the beam center of the rotating gantry of the proton therapy system, as well as the absolute position deviation of the beam spot, are within the millimeter range, to avoid large errors in dose distribution, which could lead to toxic side effects in patients.

[0003] There are very few measurement devices available on the market for this purpose, and the existing measurement devices have the following shortcomings: (1) Most of the existing measurement devices are imported, which are expensive and have high usage and maintenance costs; (2) The measurement efficiency is low, the time is long, the spatial resolution is low, and it is difficult to meet the high-precision measurement requirements; (3) The existing measurement devices need to rely on the movement of the treatment bed when positioning, and cannot adjust their position themselves. The movement of the treatment bed itself can easily introduce errors and interfere with the accuracy of the measurement results.

[0004] Therefore, there is an urgent need for a low-cost, high-resolution, high-efficiency device for measuring and verifying beam position without relying on the movement of the treatment bed, in order to solve the above problems. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes a proton beam spot position measurement and verification device.

[0006] This invention proposes a proton beam spot position measurement and verification device, which is placed below the proton beam emitted by a proton therapy device and electrically connected to a control module, comprising:

[0007] The detection module, which is fixed on a hollow rotating disk by a support structure, includes a detector for receiving photoelectric signals generated by proton beam irradiation;

[0008] The rotating module includes a base I and a vertical base I fixed to the side of the base I. The hollow rotating disk is fixed on the vertical base I. The top of the rotating module is provided with a driving mechanism I for driving the hollow rotating disk to rotate. The side of the base I and the vertical base I are both provided with circular holes that are concentric with the hollow rotating disk and have the same internal diameter. A hollow cylindrical mold is embedded in the circular hole. A long rod is inserted into the inner hole of the cylindrical mold. The free end of the long rod extends toward the detector and a tungsten bead is embedded at its end.

[0009] The three-dimensional motion module includes motion mechanisms in the X, Y, and Z directions arranged sequentially from top to bottom. Each motion mechanism includes a motion platform and a drive mechanism II for moving the motion platform. The base I is fixed on the motion platform of the X-direction motion mechanism.

[0010] Preferably, the support structure includes a base II fixed to the lower half ring of the hollow rotating disk and a vertical base II fixed to the base II. A slot is provided in the middle of the vertical base II, and the detector is inserted into the slot.

[0011] Preferably, the drive mechanism I includes a drive motor I and a ball screw transmission structure electrically connected to the control module, and also includes a DB15 signal control interface I connected to the control module.

[0012] Preferably, the drive mechanism II includes a drive motor II electrically connected to the control module and a cross-shaped roller guide rail in the corresponding direction. The bottom end of the motion platform in the corresponding direction is slidably connected to the corresponding cross-shaped roller guide rail. The motion mechanism in each direction also includes a DB15 signal control interface II connected to the control module.

[0013] Preferably, a cover plate for covering the detector is provided above the slot, the middle area of ​​the cover plate is set as a hollow structure, the size of the hollow structure area is adapted to the effective measurement area of ​​the detector, and the inner edge of the cover plate covers the edge of the detector by 2mm.

[0014] Preferably, the control module includes a PLC controller, a driver, a power supply, and a housing, used to control the rotational movement of the three-dimensional motion module and the hollow rotating disk. The PLC controller has a built-in dedicated control program for sending control commands to the driver to control the speed, direction, and displacement of the drive motor I and each of the drive motors II. The housing has a power interface, multiple DB15 connectors, a communication network port, and a power switch on its side for signal and circuit transmission.

[0015] Preferably, the detector is a CMOS semiconductor image sensor with a spatial resolution of 18.5 μm, and a surface-coupled fiber optic panel and a high-precision CsI scintillator, capable of dynamically receiving photoelectric signals generated by proton beam irradiation.

[0016] Preferably, the long rod is made of acrylic material and has a cylindrical structure, with the free end of the long rod located 1 cm above the detector.

[0017] Preferably, the tungsten bead is a solid structure with a diameter of 5 mm.

[0018] In summary, the present invention has the following beneficial effects: (1) Autonomous position adjustment: The three-dimensional motion module can drive the position measurement and verification device to move in the X, Y and Z directions to achieve the purpose of position adjustment. It does not need to rely on the treatment bed. The three-directional integrated motion reduces the volume; (2) The rotation module and the three-dimensional motion module are integrated. The hollow rotating disk and the circular hole on the rotating module are concentrically designed to ensure that the rotation center of the long rod and the detection module are consistent, which improves the functional integration, reduces the overall volume, and reduces the cost; (3) The support structure rotates synchronously with the hollow rotating disk. The detector has low cost and high resolution, which improves the measurement accuracy.

[0019] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. Attached Figure Description

[0020] Figure 1 This is a three-dimensional view of the proton beam spot position measurement and verification device of this invention without the detection module installed. Figure 1 ;

[0021] Figure 2 This is a three-dimensional view of the proton beam spot position measurement and verification device of this invention without the detection module installed. Figure 2 ;

[0022] Figure 3 This is a schematic diagram of the detection module according to an embodiment of the present invention;

[0023] Figure 4 This is a partial structural diagram of the control module according to an embodiment of the present invention.

[0024] In the picture:

[0025] 1. Hollow rotating disk; 2. Base I; 3. Vertical base I; 4. Circular hole; 5. Cylindrical mold; 6. Long rod; 7. Tungsten ball; 8. X-axis motion mechanism; 9. Y-axis motion mechanism; 10. Z-axis motion mechanism; 11. Base II; 12. Vertical base II; 13. Slot; 14. Detector; 15. Cover plate; 16. Drive motor I; 17. Manual adjustment knob I; 18. DB15 signal control interface I; 19. Drive motor II; 20. Manual adjustment knob II; 21. DB15 signal control interface II; 22. Housing; 23. Power interface; 24. DB15 connector; 25. Communication network port; 26. Power switch. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar symbols denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] like Figure 1-4 As shown, the proton beam spot position measurement and verification device proposed in this embodiment is placed below the proton beam emitted by the proton therapy device and is electrically connected to a control module, including:

[0028] The detection module, which is fixed on the hollow rotating disk 1 by a support structure, includes a detector 14 for receiving photoelectric signals generated by proton beam irradiation;

[0029] The rotating module includes a base I2 and a vertical base I3 fixed to the side of the base I2. The hollow rotating disk 1 is fixed on the vertical base I3. The top of the rotating module is provided with a drive mechanism I for driving the hollow rotating disk 1 to rotate. The side of the base I2 and the vertical base I3 are both provided with circular holes 4 that are concentric with the hollow rotating disk 1 and have the same internal diameter. A hollow cylindrical mold 5 is embedded in the circular hole 4. A long rod 6 is inserted into the inner hole of the cylindrical mold 5. The free end of the long rod 6 extends toward the detector 14 and a tungsten bead 7 is embedded at its end.

[0030] The three-dimensional motion module includes motion mechanisms in the X, Y and Z directions arranged from top to bottom (X-direction motion mechanism 8, Y-direction motion mechanism 9, and Z-direction motion mechanism 10). Each motion mechanism includes a motion platform and a drive mechanism II for driving the motion platform to move. The base I2 is fixed on the motion platform of the X-direction motion mechanism 8.

[0031] Thus, autonomous position adjustment: the three-dimensional motion module can drive the position measurement and verification device to move in the X, Y, and Z directions to achieve the purpose of position adjustment, without relying on the treatment bed. The three-directional integrated motion reduces the volume; the rotation module is integrated with the three-dimensional motion module, and the hollow rotating disk 1 and the circular hole 4 on the rotating module are concentrically designed to ensure that the rotation center of the long rod 6 and the detection module are consistent, which improves the functional integration, reduces the overall volume, and reduces the cost; the support structure rotates synchronously with the hollow rotating disk 1, and the detector 14 has low cost and high resolution, improving the measurement accuracy.

[0032] Furthermore, such as Figure 3As shown, the support structure includes a base II11 fixed to the lower half-ring of the hollow rotating disk 1 and a vertical base II12 fixed to the base II11. The base II11 is firmly fixed to the hollow rotating disk 1 with screws, ensuring that the support structure rotates synchronously with the hollow rotating disk 1 and that the rotation center is consistent, preventing any off-center situation from affecting the beam spot position measurement results. A slot 13 is provided in the middle of the vertical base II12, and the detector 14 is inserted into the slot 13.

[0033] Furthermore, a cover plate 15 is provided above the slot 13 to cover the detector 14. The middle area of ​​the cover plate 15 is designed with a hollow structure, the size of which is adapted to the effective measurement area of ​​the detector 14. The inner edge of the cover plate 15 covers the edge of the detector 14 by 2mm. In this way, the detector 14 can be effectively prevented from moving or falling during rotation, while ensuring that its effective measurement area is not obstructed, thus ensuring that the detector 14 can accurately receive the photoelectric signal generated by the proton beam irradiation. Specifically, the entire support structure is made of acrylic material. Acrylic material has the characteristics of high strength and light weight, which reduces the load on the rotating module and reduces the scattering generated during proton beam irradiation, thereby reducing the impact on proton beam spot imaging and improving measurement accuracy.

[0034] The slot 13 is designed to facilitate the quick installation and replacement of the detector 14, while the cover plate 15 effectively secures the detector 14, ensuring its stability during rotation. It should be noted that the shape and size of the slot 13 are customized according to the shape of the detector 14, facilitating quick and accurate placement of the detector 14.

[0035] The detector 14 is a small-area CMOS semiconductor image sensor (CMOS Image Sensor, CIS) [a photoelectric conversion device based on complementary metal-oxide-semiconductor (CMOS) technology, which has advantages such as low power consumption, high integration, high precision, and low cost], with a spatial resolution of 18.5 μm. It is surface-coupled to an optical fiber panel and a high-precision CsI scintillator [high-precision CsI (cesium iodide) scintillator is an inorganic scintillating material widely used in radiation detection and imaging, known for its high density, high light output, and excellent energy resolution], capable of dynamically receiving photoelectric signals generated by proton beam irradiation. The CsI scintillator converts proton beam irradiation into scintillating light signals, the optical fiber panel enables efficient transmission of the light signals, and finally the CMOS semiconductor image sensor converts the light signals into electrical signals and outputs them, thereby dynamically receiving photoelectric signals generated by proton beam irradiation and accurately capturing the position information of the proton beam spot (proton beam).

[0036] It should be noted that the long rod 6 is made of acrylic and has a cylindrical structure, with its free end positioned 1 cm above the detector 14. This ensures that during the measurement process, the positioning of the tungsten bead 7 on the long rod 6 and the beam spot signal detection of the detector 14 work in coordination, providing accurate and reliable data for beam spot position measurement and verification.

[0037] Specifically, the tungsten bead 7 is a solid structure with a diameter of 5mm. The fixed end of the long rod 6 is inserted into the cylindrical mold 5, which is fixed in the circular hole 4 of the vertical base. The cylindrical mold 5 is embedded in the central hole of the vertical base I3 and remains relatively independent from the hollow rotating disk 1. Since the circular hole 4 on the side of the base I2 is concentric with the hollow rotating disk 1 and has the same diameter, the long rod 6 is spatially located at the rotation center of the hollow rotating disk 1. Before measurement, the tungsten bead 7 is imaged using the onboard imaging system of the proton therapy equipment to determine that the tungsten bead 7 is at the isocenter of the proton therapy equipment image. This ensures that the placement of the proton beam spot position measurement and verification device in this embodiment is consistent with the isocenter of the proton therapy equipment image, providing a precise spatial reference for proton beam spot position measurement and consistency verification.

[0038] In this embodiment, as Figure 1 and Figure 2 As shown, the drive mechanism I includes a drive motor I16 (which is a stepper motor, characterized by small step angle and high control precision) and a ball screw transmission structure, which are electrically connected to the control module. It also includes a DB15 signal control interface I18 connected to the control module [DB15 (D-subminiature 15pin) is a common multi-pin connector. The "DB" in its name stands for "D-type housing" (D-sub), and the number "15" indicates the number of pins], which is used to receive the automatic rotation control signal from the control module.

[0039] Among them, the ball screw transmission structure has the advantages of high transmission efficiency, high motion accuracy (angle control accuracy can reach 0.01°) and long service life. It converts the rotational motion of the drive motor I16 into the precise rotation of the hollow rotating disk 1, thereby realizing the rotational motion of the detection module.

[0040] Preferably, a manual adjustment knob I17 for driving the ball screw transmission structure can also be provided, which can be used for initial positioning by manual control.

[0041] Meanwhile, the drive mechanism II includes a drive motor II19 electrically connected to the control module and a cross-roller guide rail in the corresponding direction (a high-precision, high-rigidity, high-load-bearing, low-friction linear motion guide mechanism that achieves bidirectional load support through orthogonally arranged rollers, including cylindrical rolling elements, V-shaped guide rails and cages, with the upper and lower guide rail surfaces forming 90° V-grooves and the rollers arranged in a cross shape, simultaneously bearing radial, axial and moment loads). The bottom end of the motion platform in the corresponding direction is slidably connected to the corresponding cross-roller guide rail. The motion mechanism in each direction also includes a DB15 signal control interface II21 connected to the control module.

[0042] Preferably, three manual adjustment knobs II20 can be provided in the three directions to drive the motion mechanism in each direction, which can be used for initial positioning through manual control.

[0043] The Z-axis (vertical direction of the Z-axis) motion mechanism serves as the bottom foundation support for the three-dimensional motion module. A manual adjustment knob II20 at the front allows for manual coarse adjustment of the Z-axis position. Internally, it integrates a drive motor II19 (specifically, a servo motor with low noise and high response speed) and a set of cross-roller guides (arranged along the Z-axis). These cross-roller guides ensure the smoothness and accuracy of the Z-axis motion. A DB15 signal control interface II21 is located on the side to receive automatic control signals from the control module. The upper motion platform is secured to the lower end of the base I2 with screws. The motion platform (which can be made of aluminum alloy) ensures device stability while effectively increasing load capacity, allowing it to support the weight of components such as the rotating module and detection module above.

[0044] X-axis motion mechanism 8 and Y-axis motion mechanism 9 are horizontally placed on the motion platform above the Z-axis motion mechanism 10 and reliably fixed with screws to ensure the integrated stability of the X, Y, and Z-axis motion mechanisms 10. Manual adjustment knobs II 20 are respectively provided at the front end of X-axis motion mechanism 8 and Y-axis motion mechanism 9, facilitating initial manual fine-tuning of the X and Y directions. The motion accuracy during manual adjustment can reach 0.01mm. Internally, they also integrate drive motors II 19 and cross-roller guides (one set of cross-roller guides each in the X and Y directions). A DB15 signal control interface II 21 is provided on the side of X-axis and Y-axis motion mechanism 9 to receive commands from the control module and achieve automatic and precise movement in the X and Y directions. The manual adjustment knobs in the X, Y, and Z directions are rationally arranged and easy to operate, allowing for quick manual adjustment of the position during device placement. Combined with the automatic control function, this improves the overall placement efficiency of the device.

[0045] Preferably, such as Figure 4As shown, the control module includes a PLC controller, a driver, a power supply, and a housing 22. It controls the rotation of the three-dimensional motion module and the hollow rotating disk 1. The PLC controller has a built-in dedicated control program for sending control commands to the driver, controlling the speed, direction, and displacement of drive motor I 16 and each drive motor II 19. The housing 22 has a power interface 23, multiple DB15 connectors 24 (specifically four, connected to one DB15 signal control interface I 18 and three DB15 signal control interfaces II 21 respectively), a communication network port 25, and a power switch 26 for signal and circuit transmission. Furthermore, the control module connects to an external data processing terminal via the communication network port 25.

[0046] In summary, when using this device, first place the proton beam spot position measurement and verification device in this embodiment below the treatment head of the proton therapy system, rotate the frame of the proton therapy system to 0 degrees, adjust the position of the proton beam spot position measurement and verification device so that the tungsten bead 7 at the top of the long rod 6 is approximately located at the crossroads of the laser lights in the treatment room, and then adjust the manual adjustment knob II 20 to place the tungsten bead 7 at the center of the crossroads of the laser lights. Then, adjust the manual adjustment knob I17 to rotate the hollow rotating disk 1, so that the vertical base II12 is in a horizontal position, completing the initial positioning of the device; then rotate the gantry of the proton therapy system to a 45-degree angle, start the onboard imaging system, take KV orthogonal films, and analyze whether the tungsten bead 7 is located at the image isocenter. If there is a positional deviation, record the three-dimensional positional deviation, and drive the three-dimensional motion module to move through the automatic control function of the control module, thereby ensuring that the tungsten bead 7 is located at the image isocenter; rotate the proton therapy system gantry again to a 315-degree angle, take KV orthogonal films again, and similarly analyze the orthogonal films to confirm whether the tungsten bead 7 is located at the image isocenter. If there is still a positional deviation, drive the three-dimensional motion module to move through the automatic control function of the control module again. Finally, ensure that the tungsten bead 7 is centered in the image; start the proton therapy system, complete the preparation for the proton beam output from the pencil beam scanning, and rotate the rotating module at a set angle. The gantry of the proton therapy system rotates accordingly to an angle perpendicular to the surface of the detector 14 of the detection module. The output beam passes through the tungsten bead 7 and irradiates the detector 14. The detector 14 dynamically receives the photoelectric signal generated by the proton beam irradiation and transmits the photoelectric signal to an external data processing terminal (data transmission is achieved through the communication network port 25 of the control module). The data processing terminal analyzes and processes the signal, reconstructs the beam spot image, calculates the center position information of the proton beam spot and the projection center of the tungsten bead 7, compares the two center positions, and completes the measurement of the proton beam spot position at that angle and the verification measurement of the consistency between the image center and the beam center in one go. In addition, removing the long rod 6 before irradiating the proton beam can obtain beam spot imaging without the tungsten bead obstruction. Through data processing, the position and size information of the proton beam spot can be obtained.

[0047] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A proton beam spot position measurement and verification device, placed below the proton beam emitted by a proton therapy device, and electrically connected to a control module, characterized in that, include: The detection module, which is fixed on a hollow rotating disk by a support structure, includes a detector for receiving photoelectric signals generated by proton beam irradiation; The rotating module includes a base I and a vertical base I fixed to the side of the base I. The hollow rotating disk is fixed on the vertical base I. The top of the rotating module is provided with a driving mechanism I for driving the hollow rotating disk to rotate. The side of the base I and the vertical base I are both provided with circular holes that are concentric with the hollow rotating disk and have the same internal diameter. A hollow cylindrical mold is embedded in the circular hole. A long rod is inserted into the inner hole of the cylindrical mold. The free end of the long rod extends toward the detector and a tungsten bead is embedded at its end. The three-dimensional motion module includes motion mechanisms in the X, Y, and Z directions arranged sequentially from top to bottom. Each motion mechanism includes a motion platform and a drive mechanism II for moving the motion platform. The base I is fixed on the motion platform of the X-direction motion mechanism.

2. The proton beam spot position measurement and verification device according to claim 1, characterized in that, The support structure includes a base II fixed to the lower half ring of the hollow rotating disk and a vertical base II fixed to the base II. A slot is provided in the middle of the vertical base II, and the detector is inserted into the slot.

3. The proton beam spot position measurement and verification device according to claim 1, characterized in that, The drive mechanism I includes a drive motor I and a ball screw transmission structure electrically connected to the control module, and also includes a DB15 signal control interface I connected to the control module.

4. The proton beam spot position measurement and verification device according to claim 4, characterized in that, The drive mechanism II includes a drive motor II electrically connected to the control module and a cross-shaped roller guide rail in the corresponding direction. The bottom end of the motion platform in the corresponding direction is slidably connected to the corresponding cross-shaped roller guide rail. The motion mechanism in each direction also includes a DB15 signal control interface II connected to the control module.

5. The proton beam spot position measurement and verification device according to claim 2, characterized in that, A cover plate is provided above the slot to cover the detector. The middle area of ​​the cover plate is designed with a hollow structure. The size of the hollow structure area is adapted to the effective measurement area of ​​the detector. The inner edge of the cover plate covers the edge of the detector by 2mm.

6. The proton beam spot position measurement and verification device according to claim 4, characterized in that, The control module includes a PLC controller, a driver, a power supply, and a housing, used to control the rotational motion of the three-dimensional motion module and the hollow rotating disk. The PLC controller has a built-in dedicated control program for sending control commands to the driver to control the speed, direction, and displacement of the drive motor I and each of the drive motors II. The housing has a power interface, multiple DB15 connectors, a communication network port, and a power switch on its side for signal and circuit transmission.

7. The proton beam spot position measurement and verification device according to claim 1, characterized in that, The detector is a CMOS semiconductor image sensor with a spatial resolution of 18.5 μm, and is surface-coupled with an optical fiber panel and a high-precision CsI scintillator, which can dynamically receive photoelectric signals generated by proton beam irradiation.

8. The proton beam spot position measurement and verification device according to claim 1, characterized in that, The long rod is made of acrylic and has a cylindrical structure, with the free end of the long rod located 1 cm above the detector.

9. The proton beam spot position measurement and verification device according to claim 1, characterized in that, The tungsten bead is a solid structure with a diameter of 5 mm.

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