Tissue equivalent correction method for non-tissue equivalent materials

Abstract

The application discloses a tissue-equivalent correction method of non-tissue-equivalent material, and belongs to the technical field of radiation measurement and radiation protection. H The method comprises the following steps: performing Fourier transform on a deposited energy spectrum F(ΔE) in the non-tissue-equivalent material to obtain a deposited energy distribution H(ω); calculating a modulus M H and a phase Φ of the deposited energy distribution H(ω); correcting the modulus M C according to k; performing inverse Fourier transform on the product of the modulus M C and the phase Φ to obtain a deposited energy spectrum T(ΔE) in biological tissue under the same irradiation condition and at the same average deposited energy. According to the application, the deposited energy distribution measured in the non-tissue-equivalent material is corrected according to the variance ratio of the deposited energy spectrum in the non-tissue-equivalent material and biological tissue at the same average deposited energy, the measurement deviation caused by the non-tissue-equivalence of the detector material can be eliminated to a certain extent, and the accuracy and reliability of the tissue-equivalent measurement of the micro-dose detector are improved.

Description

Technical Field

[0001] This invention relates to the field of radiation measurement and radiation protection technology, and in particular to a method for correcting the tissue equivalence of non-tissue equivalent materials. Background Technology

[0002] In assessing the biological effects of radiation, directly measuring the deposition energy distribution in small volumes of biological tissue is impractical. Therefore, an equivalent model—a micro-dose detector—is typically used to measure the deposition energy within these small volumes. The measured deposition energy distribution is then converted to tissue equivalence using certain physical principles to derive the deposition energy distribution in the biological tissue under the given irradiation conditions. However, because detector materials are not always tissue-equivalent, the converted deposition energy distribution results deviate from the actual deposition energy spectrum in the biological tissue. Therefore, it is necessary to correct for measurement biases caused by the non-tissue equivalence of detector materials to improve the accuracy and reliability of tissue equivalence measurements using micro-dose detectors. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of the prior art and provide a method for correcting the tissue equivalence of non-tissue equivalent materials.

[0004] The objective of this invention is achieved through the following technical solution: a method for correcting the tissue equivalence of non-tissue equivalent materials, the method comprising the following steps:

[0005] Calculate the variance ratio k of the deposition energy spectrum when the average deposition energy in non-tissue equivalent materials and biological tissues is the same;

[0006] Fourier transform of the deposition energy spectrum F(ΔE) in the non-organic equivalent material yields the transformed deposition energy distribution H(ω).

[0007] Calculate the modulus M of the deposition energy distribution H(ω) H and phase Φ;

[0008] Based on the variance ratio k, the modulus M H The corrected model M is obtained by making corrections. C ;

[0009] M C After multiplying with the phase Φ, an inverse Fourier transform is performed to obtain the deposition energy spectrum T(ΔE) in biological tissues under the same irradiation conditions and with the same average deposition energy.

[0010] Compared with the prior art, the beneficial effects of the present invention are:

[0011] This invention corrects the deposition energy distribution measured in non-tissue equivalent materials by comparing the variance ratio of the deposition energy spectrum when the average deposition energy is the same in non-tissue equivalent materials and biological tissues. Simulation results show that this correction can, to some extent, eliminate measurement bias caused by the non-tissue equivalence of the detector material, improving the accuracy and reliability of tissue equivalence measurements using micro-dose detectors. The entire process is simple to operate and reduces measurement costs to some extent. Attached Figure Description

[0012] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, which are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to denote the same or similar parts. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application.

[0013] Figure 1 This is a flowchart of a method in an example of the present invention;

[0014] Figure 2 This is a flowchart of a preferred example of the method of the present invention;

[0015] Figure 3 The deposition energy spectrum is the same when the average deposition energy of 50 MeV protons is the same in silicon, soft tissue, and lithium hydride.

[0016] Figure 4 The deposition energy spectrum is the same when the average deposition energy of 100 MeV protons is the same in silicon, soft tissue, and lithium hydride materials;

[0017] Figure 5 Comparison of the equivalent correction results of the deposition energy spectrum structure in silicon with the deposition energy spectrum in soft tissue when the proton incidence is 50 MeV;

[0018] Figure 6 Comparison of the equivalent correction results of the deposition energy spectrum structure in lithium hydride with the deposition energy spectrum in soft tissue when the proton incidence is 50 MeV;

[0019] Figure 7 Comparison of the equivalent correction results of the deposition energy spectrum structure in silicon with the deposition energy spectrum in soft tissue when the proton incidence is 100MeV;

[0020] Figure 8 Comparison of the equivalent correction results of the deposition energy spectrum structure in lithium hydride with the deposition energy spectrum in soft tissue when the proton incidence is 100MeV. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the use of ordinal numbers (e.g., "first and second," "first to fourth," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] In one example, such as Figure 1 As shown, a method for correcting the microstructure equivalence of non-microstructure equivalent materials includes the following steps:

[0026] S1: Calculate the variance ratio k of the deposition energy spectrum when the average deposition energy in non-tissue equivalent materials and biological tissues is the same;

[0027] S2: Perform a Fourier transform on the deposition energy spectrum F(ΔE) in the non-structured equivalent material to obtain the transformed deposition energy distribution H(ω);

[0028] S3: Calculate the modulus M of the depositional energy distribution H(ω). H and phase Φ;

[0029] S4: Modulus M based on variance ratio k H The corrected model M is obtained by making corrections. C ;

[0030] S5: Modify M C After multiplying with the phase Φ, an inverse Fourier transform is performed to obtain the deposition energy spectrum T(ΔE) in biological tissues under the same irradiation conditions and with the same average deposition energy.

[0031] In this example, the order of step S1 can be changed; it only needs to be completed before step S4. For instance, steps S2-S3 can be executed first, followed by steps S1 and S4-S5 in sequence. In this example, the variance ratio is used to correct the magnitude of the deposition energy distribution, thereby minimizing measurement bias caused by the non-tissue equivalence of the detector material, restoring the deposition energy distribution measurement in biological tissue, and improving the accuracy and reliability of tissue equivalence measurements using micro-dose detectors.

[0032] In one example, such as Figure 2 As shown, the deposition energy spectrum F(ΔE) in non-organic equivalent materials includes the following before Fourier transform:

[0033] The deposition energy spectrum F(ΔE) of incident radiation in non-structured equivalent materials under given irradiation conditions can be obtained through software simulation.

[0034] In one example, the expression for the variance ratio k of the deposition energy spectrum when the average deposition energy in non-tissue equivalent materials and biological tissues is the same is:

[0035]

[0036] In the formula, This represents the variance of the deposition energy spectrum in non-organic equivalent materials. This represents the variance of the deposition energy spectrum in biological tissues.

[0037] In one example, the variance of the deposition energy spectrum Ω 2 The expression is:

[0038]

[0039] In the formula, α represents the thickness correction factor; ΔE mean Indicates average deposition energy; m e denoted by electron mass; c represents the speed of light; β represents the ratio of the incident radiation particle velocity to the speed of light; I represents the average ionization / excitation energy of the material.

[0040] In one example, the expression for the thickness correction factor α of the sedimentation energy spectrum variance is:

[0041]

[0042] In the formula, x represents the thickness of the irradiated material; d represents the thickness of the irradiated material when the incident radiation deposits an energy spectrum that follows a Gaussian distribution; and κ represents the energy coefficient.

[0043] In one example, the expression for the energy coefficient is:

[0044]

[0045] In the formula, the parameter r e The classical electron radius is represented by z; the atomic number of the incident radiation particle is represented by N; the atomic number of the irradiated material per unit volume is represented by Z; and T is the atomic number of the irradiated material. max This indicates the maximum energy transferred.

[0046] In one example, the modulus M of the deposition energy distribution H(ω) H The expressions for the phase Φ are as follows:

[0047]

[0048]

[0049] In the formula, ΔE represents the energy of the incident radiation deposition, and its value range is: 1≤ΔE≤N, where N represents the length of the data point; ω represents the data point corresponding to the radiation deposition energy ΔE in Fourier space.

[0050] In one example, modulo M H The corrected expression is:

[0051]

[0052] In one example, the modulus M C The expression for the inverse Fourier transform after multiplying with the phase Φ is:

[0053]

[0054] In the formula, ω represents the data point corresponding to the radiation deposition energy ΔE in Fourier space, and its value range is: 1≤ω≤N, where N represents the length of the data point; ΔE represents the energy of the incident radiation deposition.

[0055] It should be further noted that the technical features corresponding to the above examples can be combined or substituted to form new technical solutions.

[0056] Combining all the examples above, we get: Figure 2The preferred example is shown. To verify the accuracy and reliability of the method of the present invention, taking the deviation correction between the deposition energy distribution in silicon and lithium hydride materials and the deposition energy spectrum in soft tissue under the same average deposition energy in 50MeV and 100MeV proton irradiation fields as an example, the preferred example of the present invention is used to perform tissue equivalence correction on the deposition energy spectrum in silicon and lithium hydride materials under these two irradiation conditions, including the following steps:

[0057] S1: Sequentially obtain the deposition energy distributions F1(ΔE) and F2(ΔE) in silicon and lithium hydride when protons are incident at 50MeV and 100MeV;

[0058] In this example, the average deposition energy for 50 MeV proton incidence is 23 keV, and the average deposition energy for 100 MeV proton incidence is 13.5 keV. The parameters of the three materials are shown in Table 1.

[0059] Table 1 Basic parameters of the three materials

[0060] Density [g / cm3] 2.33 1 0.82 Average ionization / excitation energy [eV] 173 78 36.5

[0061] S2: Calculate the variance ratio k1 of silicon and soft tissue deposition energy spectrum, and the variance ratio k2 of lithium hydride and soft tissue deposition energy spectrum, when the average deposition energy is 23keV under 50MeV incident radiation and 13.5keV under 100MeV incident radiation.

[0062] S3: Perform Fourier transform on the deposition energy distributions F1(ΔE) and F2(ΔE) measured in silicon and lithium hydride to obtain the deposition energy distributions H1(ω) and H2(ω).

[0063] S4: Calculate the modulus of depositional energy distributions H1(ω) and H2(ω) respectively. and phase

[0064] S5: Modulate based on variance ratios k1 and k2 After correction

[0065] S6: Will With the corresponding phase The product is calculated, and then an inverse Fourier transform is performed to obtain the energy distributions T1(ΔE) and T2(ΔE) of the deposited tissue.

[0066] To verify the effectiveness of the tissue equivalence correction method of this invention, the deposition energy distribution F3(ΔE) in soft tissue under various radiation conditions, which has the same average deposition energy as that in silicon and lithium hydride, was obtained using simulation software. The deposition energy distributions T1(ΔE) and T2(ΔE) obtained using the method proposed in this invention were compared with F3(ΔE), and the results are as follows: Figures 5-8As shown, Figures 5-8 The horizontal axis ΔE represents the energy of the incident radiation deposited in the medium, and the vertical axis F(ΔE) represents the probability distribution of the deposited energy. Figure 5 Comparison of the equivalent correction results of the deposition energy spectrum structure in silicon with the deposition energy spectrum in soft tissue when the proton incidence is 50 MeV; Figure 6 Comparison of the equivalent correction results of the deposition energy spectrum structure in lithium hydride with the deposition energy spectrum in soft tissue when the proton incidence is 50 MeV; Figure 7 Comparison of the equivalent correction results of the deposition energy spectrum structure in silicon with the deposition energy spectrum in soft tissue when the proton incidence is 100MeV; Figure 8 A comparison of the equivalent correction results of the deposition energy spectrum structure in lithium hydride with that in soft tissue at a proton incidence of 100 MeV. (The above corrections are then applied.) Figures 5-8 The simulation results are compared with those before the correction. Figure 3 The image shows the deposition energy spectrum when the average deposition energy of 50 MeV protons is the same in silicon, soft tissue, and lithium hydride. Figure 4 The comparison of deposition energy spectra of 100MeV protons in silicon, soft tissue, and lithium hydride materials with the same average deposition energy shows that the deposition energy distribution obtained after correcting the non-structure equivalent material using the method of this invention has a high degree of agreement with the deposition energy distribution in soft tissue under the same conditions. That is, the method of this invention can correct the measurement deviation of deposition energy distribution caused by non-structure equivalence in the detector, improving the agreement between the measurement results and the actual results.

[0067] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A method for correcting the microstructure equivalence of non-microstructure equivalent materials, characterized in that: It includes the following steps: Calculate the variance ratio of the deposition energy spectrum when the average deposition energy in non-tissue equivalent materials and biological tissues is the same. ; Deposition energy spectrum in non-organic equivalent materials Perform a Fourier transform to obtain the transformed depositional energy distribution. ; Calculate the depositional energy distribution model and phase ; According to variance ratio Model The corrected model is obtained by making corrections. ; mold With phase After quadrature, an inverse Fourier transform is performed to obtain the depositional energy spectrum of biological tissues under the same irradiation conditions and with the same average depositional energy. ; The variance ratio of the deposition energy spectrum of the non-tissue equivalent material when the average deposition energy is the same as that in biological tissue. The expression is: ； In the formula, This represents the variance of the deposition energy spectrum in non-organic equivalent materials. This represents the variance of the deposition energy spectrum in biological tissues; The sedimentation energy spectrum variance The expression is: ； In the formula, Indicates the thickness correction factor; Indicates average deposition energy; Indicates electron mass; Represents the speed of light; It represents the ratio of the velocity of the incident radiation particle to the speed of light; This represents the average ionization / excitation energy of the material; The deposition energy distribution model and phase The expressions are as follows: ； ； In the formula, This represents the energy deposited by incident radiation, with a range of values: , Indicates the length of the data point; Represents radiation deposition energy The corresponding data points in Fourier space; Model The corrected expression is: 。 2. The method for correcting the tissue equivalence of non-tissue equivalent materials according to claim 1, characterized in that: The thickness correction factor of the sedimentation energy spectrum variance The expression is: ； In the formula, Indicates the thickness of the irradiated material; This indicates the thickness of the material in which the energy spectrum of the incident radiation deposited in the irradiated material follows a Gaussian distribution. This represents the energy coefficient.

3. The method for correcting the tissue equivalence of non-tissue equivalent materials according to claim 2, characterized in that: The expression for the energy coefficient is: ； In the formula, the parameter ; Represents the classical electron radius; Indicates the atomic number of the incident radiation particle; This indicates the number of atoms in a unit volume of irradiated material. Indicates the atomic number of the irradiated material; This indicates the maximum energy transferred.

4. The method for correcting the tissue equivalence of non-tissue equivalent materials according to claim 1, characterized in that: The mold With phase The expression for the inverse Fourier transform after multiplication is: ； In the formula, Represents radiation deposition energy The range of values ​​for the corresponding data points in Fourier space is: , Indicates the length of the data point; This represents the energy deposited by incident radiation.

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