Measuring device and measuring method for particle source water absorbed dose

Abstract

The invention discloses a device and method for measuring the water absorbed dose of a particle source, and the device comprises a charge measurement device, and a particle source support, a shutter, a diaphragm, a first water die body, a grid assembly and a second water die body which are sequentially arranged in a first direction. The particle source support is provided with a particle source. The grid electrode assembly comprises a supporting frame, a first driving module and a grid electrode group, the grid electrode group is provided with a plurality of grid electrodes which are sequentially arranged and installed on the supporting frame in the first direction, the first driving module is used for driving the supporting frame to reciprocate in the first direction, and the charge measuring device is connected with the grid electrodes so as to measure accumulated charges under unit volume. The absolute measurement of the water absorbed dose of the particle source is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of particle source water absorbed dose measurement, and particularly relates to a measurement device and a measurement method for the water absorbed dose of a particle source. Background Art

[0002] The commonly used radiation sources for particle source implantation are low dose rate (LDR) radiation sources, and typical representatives are 125 I and 103 Pd, which are called particle sources or seed sources, and the dose rate ranges from 0.4 Gy·h -1 to 2 Gy·h -1 . Their structure is a small cylindrical source, and the length is generally less than 1 cm. The radioactive substance is usually enclosed by a titanium shell. The internal structure of the source depends on the manufacturer and the source type. In order to ensure the life safety of patients during brachytherapy, medical institutions need to formulate a comprehensive quality assurance plan and at the same time formulate an accurate treatment plan through TPS to ensure the accuracy of the radiation dose received by patients during the treatment process.

[0003] Since the density of water is close to that of human tissues, the physical effects produced by water under ionizing radiation are similar to those of human tissues, and water is easily obtainable. Therefore, in the field of brachytherapy, the internationally recognized final output is the water absorbed dose at a depth of 1 cm. The AAPM recommends using the air kerma strength Sk to characterize the source strength. However, the uncertainty of the dose value of the absorbed dose obtained based on the air kerma standard is greater than the limit recommended by the IAEA dose measurement protocol (IAEA TRS 398 (2000)). According to this protocol, the uncertainty of the absorbed dose delivered to the target volume should be less than 5% (k = 1) to ensure the effectiveness of radiotherapy. Internationally, the uncertainty of the air kerma strength (air kerma rate) calibration can reach as low as within 1% (k = 1), but to obtain the absorbed dose, another parameter - the dose rate constant is required. The determination of this constant currently depends on the combination of Monte Carlo method simulation and the measurement results of TLD dosimeters, and the uncertainty of this constant is greater than 5% (k = 1). Therefore, the uncertainty of the particle source water absorbed dose obtained by the indirect measurement method is usually between 5% and 8% (k = 1). Obviously, after adding a conversion process to the determination of the absorbed dose of the brachytherapy radiation source, its uncertainty is increased. Limited by the existing measurement technology, it is difficult to reduce the uncertainty of the dose rate constant.

[0004] Therefore, how to achieve the absolute measurement of the particle source water absorbed dose is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a measuring device for the water absorbed dose of a particle source to achieve the absolute measurement of the water absorbed dose of the particle source. Another object of the present invention is to provide a measuring method for the water absorbed dose of a particle source.

[0006] A measuring device for the water absorbed dose of a particle source provided in the present application includes a charge measuring device and, along a first direction, successively includes a particle source support, a shutter, a diaphragm, a first water phantom, a grid assembly, and a second water phantom. A particle source is provided on the particle source support.

[0007] The grid assembly includes a support frame, a first driving module, and a grid group. The grid group is provided with a plurality of grids arranged successively along the first direction and mounted on the support frame. The first driving module is used to drive the support frame to reciprocate along the first direction. The charge measuring device is connected to the grid to measure the accumulated charge per unit volume.

[0008] Optionally, in the above-mentioned measuring device for the water absorbed dose of a particle source, the grid assembly further includes a first fixing plate and a second fixing plate fixedly installed at opposite ends of the grid group along the first direction. The grid group is fixedly installed on the support frame through the first fixing plate and the second fixing plate.

[0009] Optionally, in the above-mentioned measuring device for the water absorbed dose of a particle source, it further includes a shutter adjusting device. The shutter is installed at the telescopic end of the shutter adjusting device to adjust the position of the shutter along a plane perpendicular to the first direction.

[0010] Optionally, in the above-mentioned measuring device for the water absorbed dose of a particle source, the particle source includes a rotating device and a particle source installed on the rotating device, and the rotation frequency of the particle source is adjustable.

[0011] Optionally, in the above-mentioned measuring device for the water absorbed dose of a particle source, it further includes a front shielding box successively arranged between the diaphragm and the first water phantom along the first direction:

[0012] The first water phantom includes a high-voltage electrode;

[0013] The second water phantom includes a collecting electrode, a protecting electrode, and an outer shielding box covering the outer periphery of the collecting electrode and the protecting electrode. The outer shielding box is used to shield external rays.

[0014] Optionally, in the above-mentioned measuring device for the water absorbed dose of a particle source, the collecting electrode is signal-connected through a graphite rod, and a graphite layer is sprayed on the outer periphery of the collecting electrode and the protecting electrode.

[0015] Optionally, in the above-mentioned measuring device for the water absorption dose of a particle source, the outer shielding box is a box body that opens towards the gate position; the outer shielding box is in clearance fit with the collecting electrode and the protecting electrode respectively, or the outer shielding box abuts against the collecting electrode and the protecting electrode respectively.

[0016] Optionally, in the above-mentioned measuring device for the water absorption dose of a particle source, the first driving module includes:

[0017] A bottom plate, on which the gate assembly and the second water phantom are both installed;

[0018] A stepping motor;

[0019] A ball screw, which is connected to the stepping motor to drive the bottom plate to move linearly in the first direction.

[0020] Optionally, in the above-mentioned measuring device for the water absorption dose of a particle source, adjacent gates are respectively connected by resistors, and the line connecting the connection positions of the resistor and the adjacent two gates forms an acute angle with the first direction.

[0021] A method for measuring the water absorption dose of a particle source, which is realized by the above-mentioned measuring device for the water absorption dose of a particle source, includes the steps of:

[0022] When the distance between the gate assemblies is fixed, measure the leakage current with the distance between the gate assemblies fixed. Close the shutter, and use the charge integration method. Each integration is 400 s, and repeat the measurement a preset number of times at the same position, and take the average value as the measured leakage current;

[0023] Open the shutter, set the rotation frequency of the particle source to 90° / s, keep the particle source rotating, and use the charge integration method. Each integration is 800 s, and repeat the measurement a preset number of times, and take the average value as the measured value;

[0024] Change the distance between the gate assemblies and the high voltage to obtain the ionization charge values at different distances between the gate assemblies;

[0025] After rotating the particle source by 180°, repeat the above experiment;

[0026] Adjust the high voltage of the first water phantom and the high voltage of the gate assembly to negative, repeat the above measurement steps, and take the average values of the measured values and standard deviations under the negative high voltage respectively.

[0027] In the above technical solution, the measuring device for the water absorption dose of a particle source provided by the present invention includes a charge measuring device and, along a first direction, successively includes a particle source bracket, a shutter, a diaphragm, a first water phantom, a grid assembly, and a second water phantom. The particle source bracket is provided with a particle source. The grid assembly includes a support frame, a first driving module, and a grid group. The grid group is provided with a plurality of grids arranged in sequence along the first direction and mounted on the support frame. The first driving module is used to drive the support frame to reciprocate along the first direction. The charge measuring device is connected to the grid to measure the accumulated charge per unit volume.

[0028] As can be seen from the above description, in the measuring device provided in this application, by adjusting the spacing of the grid assembly, and further adopting the method of measuring the accumulated charge multiple times per unit volume with multiple plate spacings during the measurement of the particle source, the statistical error of the measurement result is reduced, and the absolute measurement of the water absorption dose of the particle source is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0030] Figure 1 It is a three-dimensional structural schematic diagram of the measuring device provided by the embodiment of the present invention;

[0031] Figure 2 It is a cross-sectional view of the measuring device provided by the embodiment of the present invention;

[0032] Figure 3 It is a partial schematic diagram of the shutter position provided by the embodiment of the present invention;

[0033] Figure 4 It is a schematic diagram of the installation position of the outer shielding box provided by the embodiment of the present invention.

[0034] Wherein Figures 1-4 In the figure: 1-grid assembly, 2-second water phantom, 3-first water phantom, 4-front shielding box, 5-diaphragm, 6-particle source bracket, 7-shutter, 8-first fixing plate, 9-support frame, 10-guide sliding assembly, 11-ball screw, 12-shutter adjusting device, 13-backing plate, 14-vertical fixing plate, 15-outer shielding box, 16-collecting electrode and protecting electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The core of the present invention is to provide a measuring device for the water absorption dose of a particle source to achieve the absolute measurement of the water absorption dose of the particle source. Another core of the present invention is to provide a measuring method for the water absorption dose of a particle source.

[0036] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0037] Please refer to Figures 1 to 4 。

[0038] In a specific embodiment, the measuring device for the water absorption dose of a particle source provided by a specific embodiment of the present invention includes a charge measuring device and, along the first direction, successively includes a particle source support 6, a shutter 7, a diaphragm 5, a first water phantom 3, a grid assembly 1, and a second water phantom 2. The grid assembly 1 includes a support frame 9, a first driving module, and a grid group. The grid group is provided with a plurality of grids arranged in sequence along the first direction and installed on the mounting frame. The first driving is used to drive the support frame 9 to reciprocate along the first direction. The charge measuring device is connected to the grid to measure the accumulated charge per unit volume.

[0039] In a specific embodiment, the first water phantom 3 includes a high-voltage electrode. The high-voltage electrode can be sprayed with graphite, and its inner surface serves as the measurement surface. The distance from the center of the particle source on the particle source support 6 can be selected as 30 cm.

[0040] The second water phantom 2 includes a collecting electrode and a guard electrode 16. In a specific embodiment, the collecting electrode is signal-connected through a graphite rod, and a graphite layer is sprayed on the outer periphery of the collecting electrode and the guard electrode 16.

[0041] Specifically, the signal wire connection method of the collecting electrode adopts the method of introducing a graphite rod. During specific assembly, graphite rods of two sizes are respectively inserted into the collecting electrode from the openings at the front and rear ends of the second water phantom 2, and then flattened according to the plane. To ensure the minimum influence of the opening area on the area of the second water phantom 2, a drill bit with a diameter of 1 mm is used for processing. However, due to the limitation of the processing technology, when the drilling depth is too large, the 1-mm drill bit is easily broken in the second water phantom 2. Therefore, a 1-mm diameter drill bit is used for processing 5 cm deep near the collecting electrode, and a 2-mm diameter drill bit is used for the next 5 cm deep, and the processing is carried out from the front and back respectively to maintain the accuracy and make them dock at the middle position. Subsequently, the entire second water phantom 2 is graphite-sprayed on the collecting electrode and the guard electrode 16. Among them, the guard electrode is sleeved on the outer periphery of the collecting electrode. Specifically, the guard electrode and the collecting electrode are isolated by an insulating ring.

[0042] Preferably, the second water phantom 2 further includes an outer shielding box 15 covering the outer periphery of the collecting electrode and the guard electrode. The outer shielding box 15 is used to shield external rays.

[0043] In specific settings, two DC high-voltage power supplies are used to supply power to the high-voltage electrode and the grid respectively. Among them, 41 grids can be arranged in the first direction, and voltages are applied to the 41 grids with a fixed potential difference. During the measurement, when changing the plate spacing (the straight-line distance between the high-voltage electrode and the collecting electrode), the magnitude of the polarization voltage is adjusted simultaneously to ensure that the internal electric field strength of the measuring device remains unchanged. The internal electric field refers to the electric field between the high-voltage electrode and the collecting electrode, and the internal electric field is made uniform through the grid. When working normally, the electric field strength in the ionization chamber is set to 10 V / mm to ensure that the ionization chamber operates in the saturation region. In specific settings, the collecting electrode and the guard electrode 16 are connected to the electrometer using a triaxial cable.

[0044] Adjacent grids are connected through resistors respectively. The resistor is connected to the connection positions of adjacent grids, and the line connecting the connection positions forms an acute angle with the first direction. Specifically, the line connecting the connections of two grids to the same resistor connection position forms an acute angle with the first direction. Specifically, the grid is a ring-shaped grid ring. 41 grid rings are arranged between the high-voltage electrode of the first water phantom 3 and the guard electrode of the second water phantom 2. The selected resistors are connected pairwise between the grids, and a zigzag method is used to connect the resistors, that is, the resistors are inclined relative to the first direction, so that all the resistors form a shape similar to a zigzag. Specifically, the grids are numbered S1 to S41, the grid closest to the high-voltage electrode is the S41th grid, the high-voltage head is connected to the S41th grid, and the S1th grid is grounded.

[0045] In a specific embodiment, the grid assembly 1 further includes a first fixing plate 8 and a second fixing plate fixedly installed at opposite ends of the grid group along the first direction. The grid group is fixedly installed on the support frame 9 through the first fixing plate 8 and the second fixing plate. After the grids are separately processed, the 41 grids are integrally fixed through the first fixing plate 8 and the second fixing plate. The outer diameter and inner diameter of the grids are integrally processed by a numerical control machine tool to ensure the overall accuracy of the grids. The finally processed 41 grids have an extremely high coaxiality of 0.05 mm. Then, the whole is connected to the bottom support frame 9 through the first fixing plate 8 and the second fixing plate at both ends for fixation. After the grid assembly 1 is assembled, a positioning fixture is made for the entire workpiece. During specific processing, the first fixing plate 8, the second fixing plate, and the support frame 9 can be processed by a numerical control machine tool. The positioning holes for installing the grids on the first fixing plate 8 and the second fixing plate have an accuracy of 0.04 mm, which ensures the overall installation accuracy and thus ensures a relatively high coaxiality of the whole.

[0046] In a specific embodiment, the ionization chamber is provided with a temperature probe, which is designed inside the ionization chamber to better measure the working environment temperature of the ionization chamber.

[0047] During specific assembly, the distance between the particle source and the aperture opening of the aperture is set to 5 cm, that is, the particle source is 5 cm away from the aperture. At the same time, the opening angle of the aperture needs to be reasonably designed. The determination of the opening angle of the aperture follows two basic principles: First, the measurement volume of the ionization chamber is determined by the radius of the incident beam to the first water phantom 3, rather than the traditional way determined by the radius of the collecting electrode. The size of the collecting electrode needs to be considered and it is ensured that at the maximum plate spacing, the radius size of the collecting electrode is at least greater than the range of the maximum energy electrons generated by the interaction in air by one time compared to the radius of the beam at the position of the collecting electrode. Second, the beam is limited within the measurement chamber volume formed between the collecting electrode and the high-voltage electrode as much as possible to avoid the beam irradiating the chamber wall to cause photon scattering.

[0048] Since the energy and dose rate of the particle source are relatively low, in order to reduce measurement errors, during the measurement of the particle source, the method of measuring the cumulative charge multiple times per unit volume with multiple plate spacings is adopted to reduce the statistical error of the measurement results.

[0049] As can be seen from the above description, in the measurement device provided by the specific embodiment of the present application, by adjusting the spacing of the grid assembly 1, and then enabling the method of measuring the cumulative charge multiple times per unit volume with multiple plate spacings during the measurement of the particle source, the statistical error of the measurement results is reduced, and the absolute measurement of the water absorption dose of the particle source is realized.

[0050] In a specific embodiment, the measurement device further includes a shutter adjustment device 12. The shutter 7 is installed at the telescopic end of the shutter adjustment device 12 to adjust the position of the shutter 7 along the plane perpendicular to the first direction. Specifically, the shutter adjustment device 12 drives the shutter 7 to move up and down. Specifically, a 5-mm lead shutter is designed for the measurement of the background and leakage current. When measuring the water absorption dose of the particle source, the shutter 7 is opened. To make the structural design more compact, the shutter 7 is designed as an up-and-down moving structure. Specifically, the shutter 7 is fixed to the electric lifting device through a fastening thread, the electric lifting device is fastened to the backing plate 13 through screws, and the backing plate 13 is fastened to the vertical fixing plate 14 through screws. Specifically, the vertical fixing plate 14 is fixed to the base of the measurement device, thereby realizing the installation of the shutter 7.

[0051] In a specific embodiment, the particle source includes a rotating device and a particle source installed on the rotating device, wherein the rotation direction of the rotating device is perpendicular to the first direction. For example, the rotating device drives the particle source to rotate along the direction perpendicular to the horizontal plane, and the rotation frequency of the particle source is adjustable. For example, the rotation frequency of the particle source is 90° / s.

[0052] In a specific embodiment, the measurement device further includes a front shielding box 4 sequentially arranged between the aperture 5 and the first water phantom 3 along the first direction.

[0053] In a specific embodiment, the outer shielding box 15 is a box body with an opening towards the gate position; the outer shielding box 15 is in clearance fit with the collector and the protection electrode 16 respectively, or the outer shielding box 15 abuts against the collector and the protection electrode 16 respectively, reducing the influence of the metal material (stainless steel) on the experimental results. The outer shielding box 15 reduces the leakage current caused by background radiation. Since the collector and the protection electrode 16 are a whole water phantom sprayed with graphite and are exposed, the outer shielding box 15 can be processed from PMMA (plexiglass). Of course, the outer shielding box 15 is not limited to this material, as long as it is a material with good insulation, such as POM, PEEK, polyethylene, etc. The outer shielding box 15 can be gently placed on the collector and the protection electrode, playing a certain protective role, and will not damage the graphite coating during the installation process, and at the same time will not introduce too many substances causing scattering.

[0054] In a specific embodiment, the first driving assembly includes a bottom plate, a stepping motor and a ball screw 11. The gate assembly 1 and the second water phantom 2 are both installed on the bottom plate. The stepping motor is connected to the ball screw 11 to drive the bottom plate to move linearly in the first direction.

[0055] For the convenience of sliding, a guiding sliding assembly 10 with sliding fit is provided at the bottom of the bottom plate. At the same time, the other end of the sliding structure of the guiding sliding assembly 10 is connected to the ball screw 11, and the whole is driven by the stepping motor to run back and forth. The movement of the gate assembly 1 is determined by the displacement of the precise ball screw 11. The movement of the gate assembly 1 is judged by the position and stroke through the installed precise magnetic grating ruler. The precise magnetic grating ruler is arranged on the side of the guiding sliding assembly 10, with an accuracy of ±0.002 mm, and the stepping motor is installed under the base for control. The ball screw 11 provides a plate spacing between the gate assembly 1 and the first water phantom 3 ranging from 0 mm to 200 mm. Specifically, limit switches are set on the base to control the stroke within the required range. The limit switches are fixed at the front and rear ends of the stroke of the ball screw 11, that is, at the positions of 0 mm and 200 mm of the movement spacing of the gate assembly 1, thereby precisely controlling the final position of the movement.

[0056] The structural dimensions of the ionization chamber are summarized as shown in Table 1.

[0057] Table 1 Summary Table of Ionization Chamber Structural Dimensions

[0058]

[0059]

[0060] In the table, the water phantom material refers to the materials of the first water phantom and the second water phantom. The gate fixing piece is used to fix the gate. Gate fixing pieces are arranged on the relative two sides along the direction perpendicular to the gate arrangement direction. The gate fixing piece is provided with a slot opened according to the gate thickness to clamp the gate.

[0061] The measuring device provided by the present application can achieve the absolute measurement and accurate determination of the water absorbed dose of the particle source, reduce the uncertainty of the water absorbed dose of the particle source to 5% (k = 1), so as to ensure the effectiveness of particle implantation therapy.

[0062] A measuring method for the water absorbed dose of a particle source provided by the present application is implemented by the above-mentioned measuring device for the water absorbed dose of a particle source, and includes the steps:

[0063] When the distance between the grid assemblies 1 is fixed, under the condition that the distance between the grid assemblies 1 is fixed, the leakage current is measured. The shutter 7 is closed, and the charge integration method is used. Each integration is for 400 s, and repeated measurements are carried out a preset number of times at the same position, and the average value is used as the measured leakage current.

[0064] The shutter 7 is opened, the rotation frequency of the particle source is set to 90° / s, the particle source keeps rotating, and the charge integration method is adopted. Each integration is for 800 s, and repeated measurements are carried out a preset number of times, and the average value is used as the measured value.

[0065] The distance between the grid assemblies 1 and the high voltage are changed to obtain the ionization charge values at different distances between the grid assemblies 1.

[0066] After the particle source is rotated 180°, the above experiment is repeated.

[0067] The high voltage of the grid assembly 1 of the high voltage box of the first water phantom 3 is adjusted to be negative, the above measurement steps are repeated, and the average values of the measured values and standard deviations under the negative high voltage are taken respectively.

[0068] Since the placement direction of the particle source will affect the source intensity, special attention needs to be paid to the measurement accuracy of the source intensity. By measuring the source 8 times (4 times in the upright position and 4 times in the inverted position), finally, the average value of the 8 measurement results is used as the measured value of the water absorbed dose.

[0069] Specifically, when the distance between the plates is fixed, first, the leakage current is measured. The shutter 7 is closed, and the charge integration method is used. Each integration is for 400 s, and four repeated measurements are carried out at the same position, and the average value is used as the leakage current of this measurement. Subsequently, the shutter 7 is opened, the rotation frequency of the particle source is set to 90° / s, the particle source keeps rotating, and the charge integration method is adopted. Each integration is for 800 s, and four repeated measurements are carried out, and the average value is used as the measured value of this measurement. Then, by changing the distance between the plates and the high voltage, the ionization charge values at different distances between the plates can be obtained. Finally, after the particle source is rotated 180°, the above experiment is repeated.

[0070] To eliminate the polarity effect under positive and negative high voltages, adjust the high voltage of the high-voltage electrode and the high voltage of the grid electrode to negative, repeat the measurement steps under positive high voltage, and take the average values of the measurement values and standard deviations under positive and negative high voltages respectively.

[0071] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for measuring the absorbed dose of particle source water, characterized in that: The invention comprises a charge measurement device and, along a first direction, sequentially comprises a particle source support (6), a shutter (7), an aperture (5), a first water model body (3), a grid assembly (1) and a second water model body (2), wherein a particle source is arranged on the particle source support (6); The grid assembly (1) comprises a support frame (9), a first driving module and a grid group, the grid group comprising a plurality of grids arranged in sequence along a first direction and mounted on the support frame (9), the first driving module being used to drive the support frame (9) to reciprocate along the first direction, and the charge measuring device being connected to the grid to measure the accumulated charge per unit volume.

2. The device for measuring the absorbed dose of particle source water according to claim 1, characterized in that: The grid assembly (1) further comprises a first fixing plate (8) and a second fixing plate fixedly mounted at opposite ends of the grid group along a first direction, and the grid group is fixedly mounted on the support frame (9) via the first fixing plate (8) and the second fixing plate.

3. The device for measuring the absorbed dose of particle source water according to claim 1, characterized in that: It also comprises a shutter adjustment device (12), wherein the shutter (7) is mounted on the telescopic end of the shutter adjustment device (12) to adjust the position of the shutter (7) along a plane perpendicular to the first direction.

4. The device for measuring the absorbed dose of particle source water according to claim 1, characterized in that: The particle source comprises a rotating device and a particle source mounted on the rotating device, and the rotation frequency of the particle source is adjustable.

5. The device for measuring the absorbed dose of particle source water according to any one of claims 1 to 4, characterized in that: It also includes a front shielding box (4) which is sequentially arranged between the aperture (5) and the first water model body (3) along a first direction: The first water model body (3) comprises a high voltage electrode; The second water model body (2) comprises a collecting electrode, a protective electrode and an outer shielding box (15) arranged around the collecting electrode and the protective electrode, wherein the outer shielding box (15) is used for shielding external radiation.

6. The device for measuring the absorbed dose of particle source water according to claim 5, characterized in that: The collecting electrode is connected via a graphite rod signal, and a graphite layer is sprayed on the periphery of the collecting electrode and the protective electrode.

7. The device for measuring the absorbed dose of particle source water according to claim 5, characterized in that: The outer shielding box (15) is a box body opened toward the grid position; the outer shielding box (15) is respectively fitted with the collecting electrode and the protective electrode in a gap, or the outer shielding box (15) is respectively in contact with the collecting electrode and the protective electrode.

8. The device for measuring the absorbed dose of particle source water according to claim 1, characterized in that: The first driving module comprises: A bottom plate, the grid assembly (1) and the second water model body (2) are both mounted on the bottom plate; Stepper motor; A ball screw (11), wherein the stepping motor is connected to the ball screw (11) to drive the base plate to move linearly along a first direction.

9. The device for measuring the absorbed dose of particle source water according to claim 1, characterized in that: Adjacent gates are connected via resistors respectively, and a line connecting the resistor and two adjacent gate connection positions forms an acute angle with the first direction.

10. A method for measuring the absorbed dose of particle source water, characterized in that: The device for measuring the absorbed dose of particle source water according to any one of claims 1 to 9 comprises the following steps: When the spacing between the gate components (1) is fixed, the leakage current is measured by closing the shutter (7) and using a charge integration method. Each integration is 400 seconds. The same position is repeatedly measured a preset number of times and the average value is used as the measured leakage current. The shutter (7) is opened, the rotation frequency of the particle source is set to 90° / s, the particle source keeps rotating, and the charge integration method is adopted. Each integration is 800s, and repeated measurements are performed for a preset number of times, and the average value is taken as the measured value; Changing the grid assembly (1) spacing and the high voltage to obtain ionization charge values ​​at different grid assembly (1) spacings; Repeat the above experiment after rotating the particle source 180°; The high voltage of the first water model (3) and the high voltage of the grid assembly (1) are adjusted to be negative, the above measurement steps are repeated, and the measured values ​​and standard deviations under the negative high voltage are averaged.

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