Method for measuring the radiation dose of a mixed radiation field

Abstract

The application relates to the technical field of radiation dose measurement, and particularly provides a radiation dose measurement method for a mixed radiation field, aiming to solve the technical problem that an existing method cannot efficiently identify the radiation dose contribution in the mixed radiation field. To this end, the radiation dose measurement method for the mixed radiation field comprises the following steps: fixing a first film and a second film in the same radiation field, and controlling the irradiation environment of the first film and the second film to be consistent; obtaining a first film gray-scale image and a second film gray-scale image after irradiating the first film and the second film; determining an actual gamma dose based on the first film gray-scale image; and determining an actual neutron dose based on the second film gray-scale image and the actual gamma dose. In this way, the actual gamma dose and the actual neutron dose can be accurately identified from the mixed radiation field.

Description

Technical Field

[0001] This invention relates to the field of radiation dose measurement technology, and specifically provides a method for measuring radiation dose in a mixed radiation field. Background Technology

[0002] In the field of radiation measurement and application, existing technologies have the following significant drawbacks:

[0003] 1. Limitations of Single Radiation Response: Conventional radiotherapy films (such as Gafchromic EBT and Ashland HD-V2) are only sensitive to electromagnetic radiation such as photons and X-rays, and have extremely low response to neutron fields. Although a few films (such as EBT4) can respond to neutrons, they cannot distinguish the independent dose contributions of neutrons and gamma rays in a mixed field, resulting in measurement results containing the superposition effect of the two types of radiation, which cannot meet the requirements for accurate separation.

[0004] 2. Inefficiency of neutron field measurement: Traditional neutron field measurement relies on activation methods, which require indirect dose calculation through the activation reaction of radioactive nuclides. The operation process is complex (involving sample preparation, radioactivity measurement, and data fitting), and can only provide single-point or low-resolution dose data, making it difficult to intuitively present the spatial distribution of the neutron field (such as the detection of the uniformity of collimated beams in neutron radiography).

[0005] Therefore, there is an urgent need for a method that can efficiently identify the radiation dose contribution in a mixed radiation field. Summary of the Invention

[0006] To overcome the aforementioned shortcomings, this application is proposed to provide a solution, or at least a partial solution, to the technical problem that existing methods cannot efficiently identify radiation dose contributions in mixed radiation fields. This application provides a method for measuring radiation dose in mixed radiation fields.

[0007] In a first aspect, this application provides a method for measuring radiation dose in a mixed radiation field, the method comprising:

[0008] The first film and the second film are fixed in the same radiation field to control the irradiation environment of the first film and the second film to be consistent.

[0009] After irradiating the first film and the second film, obtain grayscale images of the first film and the second film after irradiation;

[0010] The actual gamma dose is determined based on the grayscale image of the first film.

[0011] The actual neutron dose is determined based on the grayscale image of the second film and the actual gamma dose.

[0012] In one embodiment of the radiation dose measurement method for a mixed radiation field, before acquiring the grayscale images of the first and second films after irradiation, the method further includes:

[0013] The first film was calibrated using a single gamma radiation field to obtain the mapping relationship between the film gray value and the gamma dose;

[0014] Verify the gamma response consistency of the second film in a single gamma radiation field so that the second film has the same mapping relationship between film grayscale value and gamma dose as the first film.

[0015] In one embodiment of the radiation dose measurement method for a mixed radiation field, determining the actual gamma dose based on the first film grayscale image includes:

[0016] Extract the grayscale value of the first film from the grayscale image of the first film;

[0017] The actual gamma dose is calculated based on the grayscale value of the first film and the mapping relationship.

[0018] In one embodiment of the radiation dose measurement method for a mixed radiation field, determining the actual neutron dose based on the second film grayscale image and the actual gamma dose includes:

[0019] Extract the grayscale value of the second film from the grayscale image of the second film;

[0020] The actual total dose is calculated based on the grayscale value of the second film and the mapping relationship;

[0021] The actual neutron dose is determined based on the actual total dose and the actual gamma dose.

[0022] In one embodiment of the radiation dose measurement method for a mixed radiation field, determining the neutron dose based on the second film grayscale image and the gamma dose includes:

[0023] Extract the grayscale value of the second film from the grayscale image of the second film;

[0024] The actual total dose is calculated based on the grayscale value of the second film and the mapping relationship;

[0025] Obtain the characteristic parameters of the radiation field;

[0026] A simulation environment consistent with the radiation field is constructed based on the characteristic parameters of the radiation field.

[0027] The theoretical gamma dose and theoretical neutron dose are obtained based on the simulated environment.

[0028] The neutron contribution factor is determined based on the theoretical gamma dose and theoretical neutron dose.

[0029] The actual neutron dose is obtained by multiplying the neutron contribution factor and the actual total dose.

[0030] In one embodiment of the radiation dose measurement method for a mixed radiation field, the first film includes a first substrate layer, a second substrate layer, and a first sensitive layer located between the first substrate layer and the second substrate layer, wherein the first sensitive layer produces a radiochromic response to gamma rays;

[0031] The second film includes a third substrate layer, a fourth substrate layer, and a neutron ray response layer and a second sensitive layer located between the third substrate layer and the fourth substrate layer. The neutron ray response layer generates charged particles, and the second sensitive layer is sensitive to both the charged particles and gamma rays.

[0032] In one embodiment of the radiation dose measurement method for a mixed radiation field, the thickness of the first substrate layer is greater than the thickness of the third substrate layer, the thickness of the third substrate layer is greater than the thickness of the fourth substrate layer, and the thickness of the fourth substrate layer is equal to that of the second substrate layer.

[0033] In one embodiment of the radiation dose measurement method for a mixed radiation field, the first substrate layer, the second substrate layer, the third substrate layer, and the fourth substrate layer are all polyethylene terephthalate, the first sensitive layer and the second sensitive layer are both triarylmethane, and the neutron ray response layer is lithium oxide.

[0034] In one embodiment of the radiation dose measurement method for a mixed radiation field, controlling the irradiation environment of the first film and the second film to be consistent includes: controlling the beam intensity and beam time of the neutron source to be consistent for the first film and the second film, and controlling the spatial deviation of the placement positions of the first film and the second film to be within a preset range.

[0035] In one embodiment of the radiation dose measurement method for a mixed radiation field, acquiring the grayscale images of the first and second films after irradiation includes:

[0036] The first and second films after irradiation are left to stand for a preset time;

[0037] A scanner is used to scan the first film and the second film to obtain grayscale images of the first film and the second film, respectively.

[0038] The above-described technical solutions of this application have at least one or more of the following features. Beneficial effects:

[0039] The radiation dose measurement method for a mixed radiation field in this application includes: firstly, fixing a first film and a second film in the same radiation field and controlling the irradiation environment of the first film and the second film to be consistent; after irradiating the first film and the second film, acquiring grayscale images of the first film and the second film after irradiation; determining the actual gamma dose based on the grayscale image of the first film; and determining the actual neutron dose based on the grayscale image of the second film and the actual gamma dose. In this way, the actual gamma dose and the actual neutron dose can be accurately identified from the mixed radiation field, realizing the simultaneous measurement of the dose distribution of neutrons and photons (gamma rays) in a two-dimensional plane. Attached Figure Description

[0040] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0041] Figure 1 This is a schematic diagram of the main process of a radiation dose measurement method for a mixed radiation field in one embodiment of this application;

[0042] Figure 2 This is a schematic diagram of the process for determining the neutron dose in one embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the process for determining the neutron dose in another embodiment of this application. Detailed Implementation

[0044] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0045] Current traditional methods for measuring radiation dose have the following significant drawbacks:

[0046] 1. Limitations of Single Radiation Response: Conventional radiotherapy films (such as Gafchromic EBT and Ashland HD-V2) are only sensitive to electromagnetic radiation such as photons and X-rays, and have extremely low response to neutron fields. Although a few films (such as EBT4) can respond to neutrons, they cannot distinguish the independent dose contributions of neutrons and gamma rays in a mixed field, resulting in measurement results containing the superposition effect of the two types of radiation, which cannot meet the requirements for accurate separation.

[0047] 2. Inefficiency of neutron field measurement: Traditional neutron field measurement relies on activation methods, which require indirect dose calculation through the activation reaction of radioactive nuclides. The operation process is complex (involving sample preparation, radioactivity measurement, and data fitting), and can only provide single-point or low-resolution dose data, making it difficult to intuitively present the spatial distribution of the neutron field (such as the detection of the uniformity of collimated beams in neutron radiography).

[0048] Therefore, this application proposes a method for measuring radiation dose in a mixed radiation field.

[0049] See appendix Figure 1 , Figure 1 This is a schematic flowchart of the main steps of a method for measuring radiation dose in a mixed radiation field according to an embodiment of this application.

[0050] like Figure 1 As shown, the radiation dose measurement method for the mixed radiation field in this application embodiment mainly includes the following steps S10-S40.

[0051] Step S10: Fix the first film and the second film in the same radiation field to ensure that the irradiation environment of the first film and the second film is consistent.

[0052] Step S20: After irradiating the first film and the second film, acquire the grayscale images of the first film and the second film after irradiation.

[0053] Step S30: Determine the actual gamma dose based on the grayscale image of the first film;

[0054] Step S40: Determine the actual neutron dose based on the grayscale image of the second film and the actual gamma dose.

[0055] Based on steps S10-S40 above, the first and second films are first fixed in the same radiation field, and the irradiation environment for the first and second films is controlled to be consistent. After irradiating the first and second films, grayscale images of the first and second films after irradiation are acquired. The actual gamma dose is determined based on the grayscale image of the first film. The actual neutron dose is determined based on the grayscale image of the second film and the actual gamma dose. In this way, the actual gamma dose and the actual neutron dose can be accurately identified from the mixed radiation field, realizing the simultaneous measurement of the dose distribution of neutrons and photons (gamma rays) in a two-dimensional plane, which is applicable to scenarios such as neutron radiography, beam collimation detection, and mixed-field radiotherapy quality control.

[0056] The following provides further explanation of steps S10 to S40.

[0057] Regarding step S101 above, in one specific embodiment, controlling the irradiation environment of the first film and the second film to be consistent includes: controlling the beam intensity and beam emission time of the neutron source to be consistent for the first film and the second film, and controlling the spatial deviation of the placement positions of the first film and the second film to be within a preset range.

[0058] Specifically, the first and second films can be fixed parallel to each other on the same plane of the radiation field to be tested (such as at the collimated beam outlet of neutron radiography) to ensure that the irradiation environment is completely consistent: including the neutron source beam intensity, beam exit time (error ≤ ±1%), and film placement position (spatial deviation ≤ 50 μm), thereby eliminating the interference of environmental variables on dose measurement.

[0059] The structure and composition of the first and second films in this embodiment will be explained in detail below.

[0060] In one specific embodiment of this application, the first film includes a first substrate layer, a second substrate layer, and a first sensitive layer located between the first substrate layer and the second substrate layer, wherein the first sensitive layer generates a radiochromic response to gamma rays; the second film includes a third substrate layer, a fourth substrate layer, and a neutron ray-responsive layer and a second sensitive layer located between the third substrate layer and the fourth substrate layer, wherein the neutron ray-responsive layer generates charged particles, and the second sensitive layer is sensitive to both the charged particles and gamma rays. The thickness of the first substrate layer is greater than the thickness of the third substrate layer, the thickness of the third substrate layer is greater than the thickness of the fourth substrate layer, and the thickness of the fourth substrate layer is equal to that of the second substrate layer. Exemplarily, the first substrate layer, the second substrate layer, the third substrate layer, and the fourth substrate layer are all polyethylene terephthalate, the first sensitive layer and the second sensitive layer are both triarylmethane, and the neutron ray-responsive layer is lithium oxide.

[0061] Specifically, the first film (gamma-ray responsive film) is a three-layer composite structure, including a first substrate layer, a second substrate layer, and a first sensitive layer located between the first and second substrate layers. Both the upper and lower substrate layers (the first and second substrate layers) are made of polyethylene terephthalate (PET) to provide mechanical support and environmental isolation. For example, the thickness of the first substrate layer (lower layer) can be 150 μm, and the thickness of the second substrate layer (upper layer) can be 50 μm.

[0062] The first sensitive layer is an active dose-sensitive layer, which can be made of a triarylmethane dye that only produces a radiochromic response to gamma rays. Under radiation, the dye molecules undergo an oxidation ring-opening reaction to generate conjugated chromophores, and the color depth (grayscale value) is linearly positively correlated with the gamma dose. For example, the thickness of the first sensitive layer can be 30 μm.

[0063] The second film (neutron-photon dual-response film) is a four-layer composite structure, including a third substrate layer, a fourth substrate layer, and a neutron beam-response layer and a second sensitive layer located between the third and fourth substrate layers. Both the third and fourth substrate layers are made of polyethylene terephthalate (PET). For example, the thickness of the third substrate layer (lower layer) can be 120 μm, and the thickness of the fourth substrate layer (upper layer) can be 50 μm.

[0064] The material of the neutron ray responsive layer can be lithium oxide (Li₂O) containing natural lithium isotopes ( 6 Li, 7 Li). Among them, 6 Li undergoes a nuclear reaction with thermal neutrons: Li⁶ + n → He⁴ + H₃, producing alpha particles. 4 He) and tritium nucleus (T); 7 Li reacts with fast neutrons through elastic scattering to produce recoil protons, which in turn excite the adjacent active layer to generate a color signal. For example, the thickness of the neutron-response layer can be 5 μm.

[0065] The second sensitive layer is an active dose-sensitive layer, which can be 30 μm thick and made of triarylmethane dye. It is closely attached to the neutron response layer and is sensitive to both charged particles and gamma rays generated by the neutron reaction. Its color depth corresponds to the superposition effect of neutron and photon doses.

[0066] The above is a further explanation of step S10. Step S20 will be further explained below.

[0067] In one specific embodiment of this application, before acquiring the grayscale images of the first and second films after irradiation, the method further includes: calibrating the first film using a single gamma radiation field to obtain the mapping relationship between the film grayscale value and the gamma dose; and verifying the gamma response consistency of the second film in a single gamma radiation field so that the second film and the first film have the same mapping relationship between the film grayscale value and the gamma dose.

[0068] Specifically, before performing step S20, a single gamma radiation field (such as...) can be further employed. 60 Co source) was used to calibrate the two types of film.

[0069] Specifically, for the first film, a single gamma radiation field (such as...) is used. 60 The Co source is used to calibrate the first film, establishing a mapping relationship between the film's grayscale value and the gamma dose, i.e., a calibration curve. This calibration curve can be represented as... in The fitting coefficients can be determined through dose gradient experiments (0.1-10 Gy); This is the calibrated dose value. It is the grayscale value of the film.

[0070] For the second film, its gamma response consistency was verified in a pure gamma field, confirming that the response function of its active layer to gamma rays is the same as that of the first film. Ensure that the standard for gamma dose measurement is consistent across dual-film setups.

[0071] Specifically, regarding step S20 above, in one specific embodiment of this application, obtaining the grayscale image of the first film and the grayscale image of the second film after irradiation includes: after the first film and the second film have been left to stand for a preset time, scanning them with a scanner to obtain the grayscale image of the first film and the grayscale image of the second film, respectively.

[0072] The preset duration can be a pre-set duration, which can be obtained based on actual experimental measurements and is not specifically limited thereto. For example, 24 hours, 36 hours, 48 ​​hours, etc. can be used as examples of the preset duration.

[0073] Specifically, the first and second films after irradiation can be left to stand for a preset time to ensure the color signal is stable. Then, a high-resolution scanner (e.g., with an accuracy of ≥1000dpi) is used to obtain grayscale images of the first and second films.

[0074] The above is a further explanation of step S20. Step S30 will be further explained below.

[0075] Specifically, step S30 can be implemented through the following steps S301 to S302.

[0076] Step S301: Extract the grayscale value of the first film from the grayscale image of the first film.

[0077] Specifically, the pixel value of each pixel can be extracted from the grayscale image of the first film to obtain the grayscale value of the first film.

[0078] Step S302: Calculate the actual gamma dose based on the grayscale value of the first film and the mapping relationship.

[0079] Specifically, the grayscale value of the first film can be directly substituted into the mapping relationship for calculation to obtain the actual gamma dose corresponding to the grayscale value of the first film.

[0080] The above is a further explanation of step S30. Step S40 will be further explained below.

[0081] Specifically, in one embodiment, such as Figure 2 As shown, step S40 can be achieved through the following steps S401 to S403.

[0082] Step S401: Extract the grayscale value of the second film from the grayscale image of the second film.

[0083] Specifically, the pixel value of each pixel can be extracted from the grayscale image of the second film to obtain the grayscale value of the second film.

[0084] Step S402: Calculate the actual total dose based on the grayscale value of the second film and the mapping relationship.

[0085] Specifically, the grayscale value of the second film can be directly substituted into the mapping relationship for calculation to obtain the total dose (including the sum of neutron and gamma doses) corresponding to the grayscale value of the second film.

[0086] Step S403: Determine the actual neutron dose based on the actual total dose and the actual gamma dose.

[0087] Specifically, the actual neutron dose can be obtained by subtracting the actual gamma dose from the actual total dose, thus achieving the separation of neutron contributions.

[0088] Specifically, in another embodiment, such as Figure 3 As shown, step S40 can be implemented through the following steps S411 to S417.

[0089] Step S411: Extract the grayscale value of the second film from the grayscale image of the second film.

[0090] Specifically, the pixel value of each pixel can be extracted from the grayscale image of the second film to obtain the grayscale value of the second film.

[0091] Step S412: Calculate the actual total dose based on the grayscale value of the second film and the mapping relationship.

[0092] Specifically, the grayscale value of the second film can be directly substituted into the mapping relationship for calculation to obtain the total dose (including the sum of neutron and gamma doses) corresponding to the grayscale value of the second film.

[0093] Step S413: Obtain the characteristic parameters of the radiation field.

[0094] Specifically, the characteristic parameters of the actual radiation field include the neutron energy distribution (such as the ratio of thermal neutrons to fast neutrons), flux (particle beam per unit time), and gamma spectrum, and may also include environmental conditions such as temperature and humidity.

[0095] Step S414: Construct a simulation environment consistent with the radiation field based on the characteristic parameters of the radiation field.

[0096] Specifically, the characteristic parameters of the actual radiation field can be input into Monte Carlo simulation software (such as MCNP or GEANT4) to construct a simulation environment consistent with the radiation field.

[0097] Step S415: Obtain the theoretical gamma dose and theoretical neutron dose based on the simulation environment.

[0098] Specifically, MCNP can be used to perform gamma transport simulations and neutron transport simulations to obtain the theoretical gamma dose. and theoretical neutron dose From this, the sum of the theoretical gamma dose and the theoretical neutron dose can be obtained.

[0099] Step S416: Determine the neutron contribution factor based on the theoretical gamma dose and the theoretical neutron dose.

[0100] Specifically, the neutron contribution factor R n It could be the theoretical neutron dose. With the sum D total,mc The ratio can be specifically expressed as:

[0101] Step S417: Obtain the actual neutron dose based on the product of the neutron contribution factor and the actual total dose.

[0102] Specifically, by multiplying the neutron contribution factor by the actual total dose, the neutron contribution in the actual total dose, or the actual neutron dose, can be obtained.

[0103] By correcting the differences between experiments and simulations through normalization, the accuracy of dose discrimination in complex fields was improved, and a neutron dose with high precision was obtained.

[0104] The radiation dose measurement method for the mixed radiation field of this application will now be described in detail by way of examples.

[0105] First, the film preparation process will be explained in detail.

[0106] For the first film, a slit coating method was used to uniformly coat a 30μm thick triarylmethane dye-polymer solution (15% solid content) on a 50μm PET substrate. After drying, a 150μm PET protective layer was covered, and the film was hot-pressed (at a temperature of 120℃ and a pressure of 5MPa) to form a three-layer structure.

[0107] For the second film, a 5 μm LiO thin film (e.g., Li) was deposited on a 50 μm PET substrate using magnetron sputtering. 6 The neutron response layer (95% abundance) is then coated with a 30 μm reactive dye layer, and finally covered with a 120 μm PET protective layer to ensure that the distance between the neutron response layer and the active layer is <1 μm, maximizing the energy transfer efficiency of charged particles.

[0108] Next, a calibration experiment was performed. Specifically, the two types of film were placed at a distance of... 60 At a Co source 1m, a dose rate of 1Gy / min was set, with irradiation time ranging from 0.1 to 10 minutes, generating a dose gradient of 0.1 to 10Gy. The film images were scanned and recorded using a scanner, and the OD values ​​at each dose point were measured using ImagJ software. A calibration curve was then obtained by fitting the data.

[0109] Next, mixed-field measurements were performed. Specifically, the irradiation was first set up with a neutron source, such as the DD accelerator neutron source, with a source intensity of 1e10n / s and a beam diameter of 10cm. The first and second films were placed parallel to each other 20cm behind the collimator exit and fixed with a lead frame to ensure a parallelism error of <0.1°. After irradiating the first and second films for 30 minutes, images of the first and second films were acquired using an EPSON Perfection V850 scanner (1200dpi, transmission mode), and the OD values ​​of each pixel in the first and second film images were extracted using ImagJ software.

[0110] The photon (gamma) dose distribution is calculated by substituting the gray values ​​of the first film into the mapping relationship between the film image and the gamma dose. The total dose distribution is calculated by substituting the gray values ​​of the second film into the mapping relationship between the film image and the gamma dose. Finally, the neutron dose is separated from the total dose distribution.

[0111] In addition, the MCNP can be used to simulate the neutron flux distribution at the collimator exit, calculate the theoretical neutron dose and theoretical gamma dose, and further calculate the neutron contribution factor R based on the neutron dose and theoretical gamma dose. n Finally, based on the neutron contribution factor R n The actual neutron dose is obtained by multiplying the actual total dose by the actual neutron dose. The actual neutron dose obtained by this method has a deviation of <5% compared with the result obtained by separating the neutron dose from the total dose distribution in the previous steps.

[0112] This invention provides a method for measuring the dose of a neutron-photon mixed radiation field, comprising two types of no-processing films. The first film responds only to gamma rays, while the second film, through a combination of a lithium oxide neutron-response layer and a second sensitive layer, responds to both neutrons and gamma rays. Accurate separation and two-dimensional planar distribution measurement of the two radiation components in the mixed field are achieved through synchrotron irradiation, grayscale calibration, and dual-method dose calculation (difference method and Monte Carlo simulation method). Compared to traditional techniques, this method offers advantages such as ease of operation, intuitive visualization, and high resolution, making it suitable for fields such as neutron radiography and radiotherapy quality control.

[0113] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0114] Those skilled in the art will understand that all or part of the processes in the method of the above-described embodiment can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0115] The technical solution of this application has been described in conjunction with the specific embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method of radiation dose measurement for a mixed radiation field, characterized by, The method includes: A first film and a second film are fixed in the same radiation field, and the irradiation environment of the first film and the second film is controlled to be consistent. The first film includes a first substrate layer, a second substrate layer, and a first sensitive layer located between the first substrate layer and the second substrate layer, wherein the first sensitive layer generates a radiochromic response to gamma rays. The second film includes a third substrate layer, a fourth substrate layer, and a neutron ray responsive layer and a second sensitive layer located between the third substrate layer and the fourth substrate layer. The neutron ray responsive layer generates charged particles, and the second sensitive layer is sensitive to both the charged particles and gamma rays. The first film is calibrated using a single gamma radiation field to obtain the mapping relationship between film grayscale value and gamma dose; the gamma response consistency of the second film is verified in a single gamma radiation field so that the second film and the first film have the same mapping relationship between film grayscale value and gamma dose. After irradiating the first film and the second film, obtain the grayscale images of the first film and the second film after irradiation; The actual gamma dose is determined based on the grayscale image of the first film. Determining the actual neutron dose based on the second film grayscale image and the actual gamma dose includes: Extract the grayscale value of the second film from the grayscale image of the second film; The actual total dose is calculated based on the grayscale value of the second film and the mapping relationship; The actual neutron dose is determined based on the actual total dose.

2. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The determination of the actual gamma dose based on the grayscale image of the first film includes: Extract the grayscale value of the first film from the grayscale image of the first film; The actual gamma dose is calculated based on the grayscale value of the first film and the mapping relationship.

3. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The determination of the actual neutron dose based on the actual total dose includes: The actual neutron dose is determined based on the difference between the actual total dose and the actual gamma dose.

4. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, Determining the actual neutron dose based on the actual total dose includes: Obtain the characteristic parameters of the radiation field; A simulation environment consistent with the radiation field is constructed based on the characteristic parameters of the radiation field. The theoretical gamma dose and theoretical neutron dose are obtained based on the simulated environment. The neutron contribution factor is determined based on the theoretical gamma dose and theoretical neutron dose. The actual neutron dose is obtained by multiplying the neutron contribution factor and the actual total dose.

5. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The thickness of the first substrate layer is greater than the thickness of the third substrate layer, the thickness of the third substrate layer is greater than the thickness of the fourth substrate layer, and the thickness of the fourth substrate layer is equal to that of the second substrate layer.

6. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The first substrate layer, the second substrate layer, the third substrate layer and the fourth substrate layer are all polyethylene terephthalate, the first sensitive layer and the second sensitive layer are both triarylmethane, and the neutron ray response layer is lithium oxide.

7. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The control of ensuring consistent irradiation environments for the first and second films includes: controlling the beam intensity and beam emission time of the neutron source to be consistent for the first and second films, and controlling the spatial deviation of the placement positions of the first and second films to be within a preset range.

8. The method for measuring radiation dose in a mixed radiation field according to claim 1, characterized in that, The acquisition of the first and second grayscale images of the irradiated film includes: The first and second films after irradiation are left to stand for a preset time; A scanner is used to scan the first film and the second film to obtain grayscale images of the first film and the second film, respectively.

Images