Method and device for measuring dose equivalent of mixed radiation field based on optical fiber-OSL

Abstract

The invention discloses an optical fiber-OSL-based mixed radiation field dose equivalent measurement method and device, relates to the technical field of radiation measurement, and solves the technical problem that the measurement of dose equivalent in a mixed radiation field is not accurate enough. According to the technical scheme, the method is characterized in that the average detection efficiency and the average energy transfer linear density in the mixed radiation field are obtained through fitting calculation of a luminescence decay curve of an OSL crystal, the actually measured dose is corrected, and therefore measurement of the dose equivalent of the mixed radiation field is achieved. The invention provides a new method for evaluating the dose of the space radiation field, realizes the accurate measurement of the dose equivalent of the mixed radiation field, and improves the measurement accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radiation measurement, and in particular to a mixed radiation field dose equivalent measurement method and device based on optical fiber-OSL. BACKGROUND

[0002] The light emission principle of an OSL (Optically Stimulated Luminescence) crystal is shown in FIG. 1. After the OSL crystal is irradiated by radiation, the electrons in the valence band are excited to the conduction band, and then are trapped by the trapping levels in the forbidden band, and the radiation energy is stored. When the crystal is irradiated by light of a specific wavelength, the electrons in the trapping levels jump to the conduction band. The electrons recombine with the luminescent centers in the forbidden band, and emit fluorescent photons in a certain wavelength range. The size of the light emission is proportional to the radiation dose. Figure 1

[0003] The space radiation environment is a complex mixed radiation field, including various rays such as gamma rays, electrons, protons, neutrons, alpha particles and high-energy heavy ions. Therefore, the influence of various ray particles must be considered when measuring the space radiation dose. For a mixed radiation field, the contribution of different types of radiation needs to be considered when calculating the total absorbed dose D, which is shown in the following formula:

[0004] D = ∑ i D i (1)

[0005] According to formula (1), the absorbed dose needs to know the dose D i contributed by different rays i in the mixed radiation field under study. However, for unknown mixed radiation fields, it is difficult to distinguish and measure the dose D i of various rays by using traditional active and passive dose measurement methods.

[0006] For radiation of different LET (linear energy transfer), the response of the OSL crystal is different. For low-LET radiation such as gamma or X-rays, the energy is almost uniformly deposited in the OSL crystal. The energy of high-LET charged particles is deposited along the particle track, and the dose deposited at the center of the track can be as high as 10 5 Gy, and the dose deposited away from the center of the track is lower and inversely proportional to the square of the distance from the center of the track. Due to the difference in the spatial deposition of particle energy, the response of the OSL crystal to different types of radiation will be significantly different. Therefore, how to accurately measure the dose equivalent in the mixed radiation field by OSL remains to be solved. SUMMARY

[0007] ​The application provides a mixed radiation field dose equivalent measurement method and device based on an optical fiber-OSL, and the technical objective is to accurately measure the dose equivalent in a mixed radiation field.

[0008] The above technical objective of the application is achieved by the following technical solutions:

[0009] A mixed radiation field dose equivalent measurement method based on an optical fiber-OSL, comprising:

[0010] According to the detection efficiency η of different LET particles, a LET-η relationship curve of each LET particle is obtained; wherein the detection efficiency η of different LET particles is obtained by an OSL probe;

[0011] The OSL light emission decay curves of different LET particles are fitted respectively to obtain fitting parameters τ1, and a LET-τ1 relationship curve of each LET particle is obtained according to the fitting parameters τ1;

[0012] The OSL light emission decay curve of the mixed radiation field is fitted to obtain fitting parameters τ2, and a LET-τ2 relationship curve of the mixed radiation field is obtained according to the fitting parameters τ2;

[0013] The fitting parameters τ2 are substituted into the LET-τ1 relationship curve to obtain the average energy transfer line density LET mean of the mixed radiation field;

[0014] According to the average energy transfer line density LET mean , the quality factor is estimated;

[0015] The average energy transfer line density LET mean is substituted into the LET-η relationship curve to obtain the average detection efficiency η mean of the mixed radiation field;

[0016] According to the average detection efficiency η mean , the measured absorbed dose is corrected to obtain a corrected mixed radiation field absorbed dose;

[0017] According to the corrected mixed radiation field absorbed dose and the quality factor, the mixed radiation field dose equivalent is obtained.

[0018] Further, the fitting of the OSL light emission decay curve of the mixed radiation field is represented as:

[0019]

[0020] Wherein, I OSL represents the OSL light emission decay curve of the mixed radiation field obtained after fitting; I OSL,k represents the kth light emission decay curve conforming to the exponential decay law; t represents time; A kI k (t) represents the kth light emission decay curve at time t=0 OSL,k value of I k (t) k represents the decay time constant, every other t k , I k (t) OSL,k value is reduced by 1 / e.

[0021] Further, the quality factor is represented as:

[0022]

[0023] wherein Q(L) represents the quality factor of the mixed radiation field based on the average linear energy transfer LET mean ; L represents the average linear energy transfer LET mean .

[0024] Further, the measured absorbed dose is corrected according to the average detection efficiency η mean to obtain the corrected absorbed dose of the mixed radiation field, represented as:

[0025]

[0026] wherein D represents the corrected absorbed dose of the mixed radiation field; D sum represents the total measured dose of the mixed radiation field, D sum =∑ i D i , D i represents the dose contributed by the i-th ray in the mixed radiation field.

[0027] Further, the dose equivalent of the mixed radiation field is represented as: H=Q(L)D.

[0028] Further, the fitting parameter τ2 is represented as:

[0029] τ2=t1 / t2;

[0030] wherein t1 represents the time t=1; t2 represents the time t=2.

[0031] Further, the LET particle is any one of neutron, proton, 4 He, 12 C, 20 Ne, 28 Si, 56 Fe, and the mixed radiation field is any combination of particles of neutron, proton, 4 He, 12 C, 20 Ne, 28 Si, 56 Fe.

[0032] A kind of hybrid radiation field dose equivalent measurement device based on fiber-OSL, the measurement device is used to realize the measurement method described in any of the above, the measurement device includes OSL probe, optical fiber, excitation light source, photomultiplier, first filter, second filter, control unit and computing unit;Control unit controls excitation light source to emit light, excitation light is transmitted to OSL probe by first filter again by optical fiber, the radiation deposited in OSL probe is excited to generate fluorescence signal, fluorescence signal is transmitted to photomultiplier by optical fiber, second filter, photomultiplier converts fluorescence signal into electrical signal and exports to control unit, control unit exports electrical signal to computing unit, computing unit carries out online measurement according to the absorbed dose of the radiation energy deposited in OSL probe according to absorbed dose, and obtains the dose equivalent of hybrid radiation field;Wherein, control unit realizes the online measurement of absorbed dose by continuously exciting the radiation energy deposited in OSL probe.

[0033] A kind of computer equipment, including memory, processor and the computer program stored in the memory and can be run on the processor, the processor carries out the computer program when realizing the hybrid radiation field dose equivalent measurement method described in any of the above.

[0034] A kind of computer storage medium, the computer storage medium stores computer program, the computer program is executed by processor when realizing the hybrid radiation field dose equivalent measurement method described in any of the above.

[0035] The beneficial effects of the present application are that the hybrid radiation field dose equivalent measurement method and device based on fiber-OSL described in the present application obtain the average detection efficiency and average energy transfer line density in hybrid radiation field by fitting calculation of the luminescence decay curve of OSL crystal, correct the measured dose, so as to realize the measurement of hybrid radiation field dose equivalent.Provide a new method for spatial radiation field dose evaluation, also realize the accurate measurement of hybrid radiation field dose equivalent, improve the measurement precision.

[0036] Meanwhile, the present application can also be used for personal dose monitoring in radiotherapy process, area dose monitoring in reactor, strong irradiation device, spent fuel pool and other strong radiation fields, has broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the schematic diagram of OSL crystal photo-induced light process;

[0038] Figure 2 It is the average energy transfer line density LET obtained from LET-τ1 relationship curve mean Schematic diagram;

[0039] Figure 3The average detection efficiency η of the mixed radiation field obtained from the LET-η curve mean schematic diagram

[0040] Figure 4 A structure diagram of the mixed radiation field dose equivalent measurement device based on fiber-OSL described in the present application. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings.

[0042] The mixed radiation field dose equivalent measurement method based on fiber-OSL described in the present application comprises:

[0043] 100: obtaining the LET-η curve of each LET particle according to the detection efficiency η of different LET particles; wherein the detection efficiency η of different LET particles is obtained by the OSL probe.

[0044] Specifically, in the accurate measurement of the mixed radiation field, the detection efficiency of the OSL probe to different LET particles (such as neutron, proton, 4He, 12C, 20Ne, 28Si, 56Fe, etc.) is determined first. The OSL probe is placed in a known particle field, the number of light emissions corresponding to the unit absorbed dose under the irradiation of different energy transfer line densities (LET) particles is determined, the detection efficiency η of different particles is calculated, and the LET-η curve is obtained.

[0045] 101: fitting the OSL light emission decay curve of different LET particles respectively to obtain fitting parameters τ1, and obtaining the LET-τ1 curve of each LET particle according to the fitting parameters τ1.

[0046] 102: fitting the OSL light emission decay curve of the mixed radiation field to obtain fitting parameters τ2, and obtaining the LET-τ2 curve of the mixed radiation field according to the fitting parameters τ2.

[0047] Preferably, the fitting of the OSL light emission decay curve of the mixed radiation field is represented as:

[0048]

[0049] wherein I OSL represents the OSL light emission decay curve of the mixed radiation field obtained after fitting; I OSL,k represents the kth light emission decay curve conforming to the exponential decay law; t represents time; A k represents the value of the kth light emission decay curve I OSL,k at t=0; t k represents the decay time constant, and every other t k , I OSL,kthe value of τ2is reduced by 1 / e.

[0050] Preferably, the fitting parameter τ2is expressed as:

[0051] τ2= t1 / t2;

[0052] wherein t1represents the time t = 1; t2represents the time t = 2.

[0053] 103: substituting the fitting parameter τ2into the LET-t1relationship curve to obtain the average linear energy transfer LET of the mixed radiation field mean , as shown in FIG. 3. Figure 2

[0054] 104: estimating the quality factor according to the average linear energy transfer LET mean .

[0055] Preferably, the quality factor is expressed as:

[0056]

[0057] wherein Q(L) represents the quality factor of the mixed radiation field based on the average linear energy transfer LET mean ; L represents the average linear energy transfer LET mean .

[0058] 105: substituting the average linear energy transfer LET mean into the LET-ηrelationship curve to obtain the average detection efficiency η of the mixed radiation field mean .

[0059] 106: correcting the measured absorbed dose according to the average detection efficiency η mean to obtain the corrected absorbed dose of the mixed radiation field.

[0060] Specifically, to achieve the mixed field radiation dose measurement, the "average detection efficiency η mean " is introduced, and the total measured dose D sum of the mixed radiation field is corrected using η mean .

[0061] Preferably, the corrected absorbed dose of the mixed radiation field is expressed as:

[0062]

[0063] wherein D represents the corrected absorbed dose of the mixed radiation field; D sum represents the total measured dose of the mixed radiation field, D sum =∑ i D i , D i represents the dose contributed by the ray i in the mixed radiation field.​

[0064] 107: The mixed radiation field dose equivalent is obtained based on the corrected mixed radiation field absorbed dose and quality factor.

[0065] Preferably, the mixed radiation field dose equivalent is expressed as: H=Q(L)D.

[0066] The hybrid radiation field dose equivalent measurement device based on optical fiber-OSL described in this application is as follows Figure 4 As shown, the measurement device is used to implement the hybrid radiation field dose equivalent measurement method described in this application. The measurement device includes an OSL probe, an optical fiber, an excitation light source, a photomultiplier tube, a first filter, a second filter, a control unit, and a calculation unit. The calculation unit is composed of several functional modules of computer software.

[0067] In actual radiation measurement, an OSL probe is placed in a radiation field. The control unit controls the excitation light source to emit light. The excitation light passes through filter A to ensure its monochromaticity. This light is then transmitted via optical fiber to the OSL probe, where the radiation deposited within the probe is excited to produce a fluorescence signal. This fluorescence signal is then transmitted via optical fiber to a photomultiplier tube (PMT). Filter B is installed at the coupling point between the signal transmission fiber and the PMT to reduce impurities in the fluorescence signal and improve the signal-to-noise ratio. The PMT converts the fluorescence signal into an electrical signal and outputs it to the control unit. The control unit then transmits the electrical signal to a calculation unit, which uses the electrical signal to online measure the absorbed dose of the radiation energy deposited in the OSL probe and derive the dose equivalent of the mixed radiation field based on the absorbed dose. The control unit achieves online measurement of the absorbed dose by continuously exciting the radiation energy deposited in the OSL probe.

[0068] The functions implemented by the computing unit are as follows:

[0069] According to the detection efficiency η of different LET particles, the LET-η relationship curve of each LET particle is obtained;

[0070] The OSL luminescence decay curves of different LET particles are fitted respectively to obtain the fitting parameter τ1, and the LET-τ1 relationship curve of each LET particle is obtained according to the fitting parameter τ1;

[0071] The OSL luminescence attenuation curve of the mixed radiation field is fitted to obtain the fitting parameter τ2, and the LET-τ2 relationship curve of the mixed radiation field is obtained according to the fitting parameter τ2;

[0072] Substituting the fitting parameter τ2 into the LET-τ1 relationship curve, the average linear energy transfer density LET of the mixed radiation field is obtained. mean ;

[0073] According to the average linear energy transfer density LET mean Estimate the quality factor;

[0074] The average linear energy transfer LET of the mixed radiation field is calculated according to the average absorbed dose D and the average dose rate R mean The average detection efficiency η of the mixed radiation field is obtained by substituting the average linear energy transfer LET into the LET-η relationship curve mean ;

[0075] The average detection efficiency η of the mixed radiation field is obtained by substituting the average linear energy transfer LET into the LET-η relationship curve mean The measured absorbed dose is corrected according to the average detection efficiency η to obtain the corrected absorbed dose of the mixed radiation field;

[0076] The dose equivalent of the mixed radiation field is obtained according to the corrected absorbed dose of the mixed radiation field and the quality factor.

[0077] The above is an exemplary embodiment of the present application, and the protection scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for measuring dose equivalent of hybrid radiation field based on optical fiber-OSL, characterized in that: include: The LET-η relationship curve of each LET particle is obtained according to the detection efficiency η of different LET particles; wherein the detection efficiency η of different LET particles is obtained by the OSL probe; The OSL luminescence decay curves of different LET particles are fitted respectively to obtain the fitting parameter τ1, and the LET-τ1 relationship curve of each LET particle is obtained according to the fitting parameter τ1; The OSL luminescence attenuation curve of the mixed radiation field is fitted to obtain the fitting parameter τ2, and the LET-τ2 relationship curve of the mixed radiation field is obtained according to the fitting parameter τ2; Substituting the fitting parameter τ2 into the LET-τ1 relationship curve, the average linear energy transfer density LET of the mixed radiation field is obtained. mean ; According to the average linear energy transfer density LET mean Estimate the quality factor; The average linear energy transfer density LET mean Substituting into the LET-η relationship curve, the average detection efficiency η of the mixed radiation field is obtained mean ; According to the average detection efficiency η mean Correct the measured absorbed dose to obtain the corrected mixed radiation field absorbed dose; The mixed radiation field dose equivalent is obtained based on the corrected mixed radiation field absorbed dose and quality factor.

2. The mixed radiation field dose equivalent measurement method according to claim 1, wherein: The OSL luminescence attenuation curve of the mixed radiation field is fitted, which is expressed as: Among them, I OSL represents the OSL luminescence attenuation curve of the mixed radiation field obtained after fitting; I OSL,k represents the kth luminous decay curve that conforms to the exponential decay law; t represents time; A k Indicates the kth luminescence decay curve I at time t = 0 OSL,k The value of t k represents the decay time constant, every t k , I OSL,k The value of is reduced by 1 / e.

3. The mixed radiation field dose equivalent measurement method according to claim 2, characterized in that: The quality factor is expressed as: Among them, Q(L) represents the average linear energy transfer density LET mean The quality factor of the mixed radiation field; L represents the average linear energy transfer density LET mean .

4. The mixed radiation field dose equivalent measurement method according to claim 3, wherein: According to the average detection efficiency η mean The measured absorbed dose is corrected to obtain the corrected mixed radiation field absorbed dose, which is expressed as: Where D represents the corrected mixed radiation field absorbed dose; D sum represents the total measured dose of the mixed radiation field, D sum =∑ i D i , D i It represents the dose contributed by ray i in the mixed radiation field.

5. The mixed radiation field dose equivalent measurement method according to claim 4, characterized in that: The mixed radiation field dose equivalent is expressed as: H=Q(L)D.

6. The mixed radiation field dose equivalent measurement method according to claim 1, wherein: The fitting parameter τ2 is expressed as: τ2=t1 / t2; Here, t1 represents the time t=1; t2 represents the time t=2.

7. The mixed radiation field dose equivalent measurement method according to claim 1, wherein: The LET particles are neutrons, protons, 4 He, 12 C. 20 Ne, 28 4. 56 Any one of Fe, the mixed radiation field is neutrons, protons, 4 He, 12 C. 20 Ne, 28 4. 56 Any combination of particles in Fe.

8. A hybrid radiation field dose equivalent measurement device based on optical fiber-OSL, the device being used to implement the hybrid radiation field dose equivalent measurement method according to any one of claims 1 to 6, characterized in that: The measuring device includes an OSL probe, an optical fiber, an excitation light source, a photomultiplier tube, a first filter, a second filter, a control unit and a calculation unit; the control unit controls the excitation light source to emit light, the excitation light passes through the first filter and is then transmitted to the OSL probe by the optical fiber, the radiation deposited in the OSL probe is excited to generate a fluorescence signal, the fluorescence signal is transmitted to the photomultiplier tube through the optical fiber and the second filter, the photomultiplier tube converts the fluorescence signal into an electrical signal and outputs it to the control unit, the control unit then outputs the electrical signal to the calculation unit, the calculation unit performs online measurement of the absorbed dose of the radiation energy deposited in the OSL probe according to the electrical signal, and obtains the dose equivalent of the mixed radiation field according to the absorbed dose; wherein, the control unit realizes online measurement of the absorbed dose by continuously exciting the radiation energy deposited in the OSL probe.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the hybrid radiation field dose equivalent measurement method according to any one of claims 1 to 6 is implemented.

10. A computer storage medium storing a computer program, wherein: When the computer program is executed by a processor, the hybrid radiation field dose equivalent measurement method according to any one of claims 1 to 6 is implemented.

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