JP2015174963A - Radiation ray dosage measurement method and dosimeter thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a radiation ray dosage measurement method that has excellent sensitivity; and a dosimeter.SOLUTION: The radiation ray dosage measurement method comprises: a step of blocking lights having a wavelength of less than 430 nm and preparing a composition comprising diarylethene represented by formula 1a; a step of blocking lights having a wavelength of less than 430 nm and irradiating a radiation ray to the composition to form diarylethene; and a step of measuring the fluorescence intensity of the composition obtained in the foregoing step. (Rand Rare each independently a C1 to 4 alkyl group; Rand Rare each independently a C5 to 10 aryl group; Rand Rare each independently a C1 to 3 alkyl group; n is 0 or 1, - (CY)m- is alicyclic skeleton; Y is H or a halogen atom; and m is an integer of 5 to 7.).

Description

  The present invention relates to a radiation dose measurement method and a dosimeter thereof, and more particularly to a radiation dose measurement method and a dosimeter using a compound that exhibits fluorescence characteristics upon irradiation with radiation.

  A phenomenon in which two structural isomers are reversibly generated by alternately irradiating ultraviolet rays and visible light is called photochromism, and a compound exhibiting photochromism is called a photochromic compound. Photochromic compounds are used in applications such as optical recording materials, display materials, optical sensors, and light control materials.

  Diarylethene, which is one of the photochromic compounds, has excellent thermal stability, chemical stability, and repeated durability, which are particularly important characteristics in application to the above applications, and has been studied for practical use. Yes. For example, Non-Patent Document 1 discloses application of diarylethene.

As shown by the following general formula, diarylethene reversibly produces isomers (open and closed rings) by alternately irradiating ultraviolet rays and visible rays. The ring opening of diarylethene is usually colorless. When the ring-opened body is irradiated with ultraviolet light, a diarylethene ring-closed body is formed. The ring closure of diarylethene is colored. When the colored diarylethene ring-closed body is irradiated with visible light, it returns to the original colorless ring-opened body.

  Patent Document 1 discloses a diarylethene in which the aryl skeleton in the diarylethene is a benzosulfone skeleton. Specifically, a compound having a benzothiophen-1,1-dioxide-3-yl group is disclosed. Similar to the normal diarylethene represented by the above general formula, this compound is converted to a closed ring having an absorption band in the visible region when irradiated with ultraviolet rays, and when the closed ring is irradiated with visible light, the original opened state is converted. Return to the ring.

  Non-Patent Document 2 and Non-Patent Document 3 describe a method for producing the above benzosulfone-type diarylethene and the fluorescence quantum yield of the ring-closed compound in an organic solvent such as 1,4-dioxane.

  Studies have been conducted on radiation color dosimeters that utilize the coloration of diarylethene when irradiated. Patent Document 2 discloses that when a polystyrene film containing a diarylethene ring-opening body having a thiophene ring or a thiazole ring is irradiated with radiation, a ring-closing body is generated, and an irradiation dose is determined by a coloring amount of the generated ring-closing body. Has been.

Patent Document 2 discloses a study on a polystyrene film in which a diarylethene having a thiophene ring or a thiazole ring and a scintillation material are directly mixed. As a material for scintillation, BaFCl: Eu ²⁺ , CeMgAl ₁₁ O ₁₉ , CaWO ₄ , and ZnSAg are used. It is disclosed that when these are added, the coloring amount is increased by a maximum of 8 times compared to the case where no scintillation material is added.

  Patent Document 3 discloses a method of irradiating a solution containing a diarylethene ring-closed product with radiation and measuring an irradiation dose based on a coloring amount. Patent Document 4 discloses that radiation sensitivity is increased when a polymer medium having an aromatic group such as polystyrene is used. Patent Documents 5 to 7 also disclose that radiation sensitivity and stability of a colored body are improved by introducing a methoxy substituent into diarylethene.

The techniques described in Patent Documents 2 to 7 are methods for measuring an irradiation dose by detecting the degree of coloration of diarylethene using an absorption spectrometer or the like, or by comparing with a standard sample colored to a certain concentration. It is.
On the other hand, as disclosed in Non-Patent Document 4 regarding ultra-high density optical memory, it has been experimentally demonstrated that it is already possible to detect a fluorescent compound at a single molecule level.

JP 2012-172139 A JP 2003-64353 A Japanese Patent Laid-Open No. 11-258348 JP 2001-354862 A JP 2002-309244 A JP 2002-334498 A JP 2004-45037 A

Masahiro Irie, Chemical Reviews, (USA), American Chemical Society, May 2000, Vol. 100, No. 5, p. 1685-1716 Masahiro Irie, et al., Journal of the American Chemical Society, (USA), American Chemical Society, 2011, Vol. 133, p. 13558-13564 Masahiro Irie, 6 others, Photochemical & Photobiological Science, (UK), The Royal Society of Chemistry, 2012, Vol. 11, p. 1661-1665 Masahiro Irie, 4 others, “Nature”, 2002, 420, p. 759-761

  Conventional radiation dosimeters measure dose according to the degree of coloration, but such dosimeters have insufficient sensitivity. In view of such circumstances, it is an object of the present invention to provide a radiation dose measurement method and a dosimeter with excellent sensitivity.

The inventors have conceived that if the radiation dose is measured by the fluorescence intensity using diarylethene whose ring-closed body exhibits fluorescence properties, the present invention has been completed with the idea that a markedly higher sensitivity is expected. That is, the said subject is solved by the following this invention.
(1) A step of preparing a composition containing diarylethene represented by formula 1a under the shielding of ultraviolet rays and visible light having a wavelength of less than 430 nm,
Irradiating the composition with ultraviolet rays and a visible light shield having a wavelength of less than 430 nm to produce a diarylethene represented by formula 1b; and
Measuring the fluorescence intensity of the composition obtained in the step,
A method for measuring radiation dose, including:
(2) The method according to (1), wherein Y is a halogen atom, n is 0, and m is 5.
(3) The method according to (1) or (2), wherein R ³ and R ⁴ are a phenyl group or a thienyl group.
(4) A radiation dosimeter comprising a composition containing diarylethene represented by formula 1a, housed in a container that blocks ultraviolet rays and visible light having a wavelength of less than 430 nm.
(5) The radiation dosimeter according to (4), further comprising a scintillation material having a light emission characteristic in an ultraviolet region, which is disposed around the container.

  The present invention can provide a radiation dose measuring method and a dosimeter having excellent sensitivity.

Relationship between the fluorescence spectrum of compound 2a in toluene solution and the irradiation dose Relationship between fluorescence intensity of compound 2a at 530 nm and radiation dose Relationship between fluorescence intensity of compound 3a at 530 nm and radiation dose Relationship between fluorescence intensity of compound 4a at 586 nm and radiation dose Relationship between fluorescence spectrum and radiation dose of polystyrene thin film with compound 2a sandwiched between BaFCl: Eu thin films Relationship between fluorescence intensity at 530 nm and radiation dose of polystyrene thin film with compound 2a sandwiched between BaFCl: Eu thin films Relationship between fluorescence spectrum and radiation dose of polystyrene thin film to which compound 3a is added Relationship between fluorescence spectrum and radiation dose of polystyrene thin film added with compound 3a sandwiched between BaFCl: Eu thin films

Hereinafter, the present invention will be described in detail. In the present invention, “X to Y” means that both values, that is, both X and Y are included.
1. Measuring method The measuring method of radiation dose of the present invention,
A step of preparing a composition containing diarylethene represented by Formula 1a under the shielding of ultraviolet rays and visible light having a wavelength of less than 430 nm (preparation step);
A step of irradiating the composition with ultraviolet light and a visible light shield having a wavelength of less than 430 nm to produce a diarylethene represented by Formula 1b (irradiation step), and measuring the fluorescence intensity of the composition obtained in the step Including a process (measurement process).

(1) Preparation Step In this step, a composition containing a diarylethene represented by the formula 1a (hereinafter also referred to as “ring-opened product”) is prepared.

In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms. In the present invention, the alkyl group includes both a linear alkyl group and a branched alkyl group.
R ³ and R ⁴ are each independently an aryl group having 5 to 10 carbon atoms. In the present invention, the aryl group includes an aromatic hydrocarbon group and a heteroaromatic hydrocarbon group. As the aryl group, an unsubstituted or substituted phenyl group or thienyl group is preferable. In this case, the substituent is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

n is independently 0 or 1, and represents the number of R ⁵ and R ⁶ . R ⁵ and R ⁶ are alkyl groups having 1 to 3 carbon atoms. Since the synthesis may be difficult when R ⁵ and R ⁶ are present, n is preferably 0. However, when n is 1, R ⁵ and R ⁶ are preferably a methyl group or an ethyl group.
-(CY) m- represents an alicyclic skeleton. Y is a hydrogen atom or a halogen atom, m represents the number of alicyclic skeletons, and is an integer of 5 to 7. m is preferably 5, Y is preferably a halogen atom, and more preferably a fluorine atom. That is, when m is 5 and Y is a fluorine atom, it means that the compound of formula 1a has the following alicyclic skeleton.

The ring-opened product can be synthesized by a known method, for example, the method described in Non-Patent Document 2 or 3.
A composition can be prepared by dissolving or dispersing the ring-opened product in a solvent. The composition is a solution in the above case and a dispersion in the latter case. The solvent is not particularly limited, but aromatic hydrocarbons such as toluene and ethers such as 1,4-dioxane are preferable. The mixing ratio of the solvent and the ring-opened body is preferably 1 to 10 g of the ring-opened body with respect to 1 L of the solvent.

  Moreover, a composition can be prepared by dissolving or dispersing the ring-opened product in a polymer. Although it does not limit as a polymer, The polymer which has aromatic rings, such as a polystyrene and aromatic polyester, is preferable. This is because the polymer having an aromatic ring absorbs ultraviolet rays and thus has an effect of shielding ultraviolet rays against the diarylethene used in the present invention.

  A method for dissolving or dispersing the ring-opened product in the polymer is not limited, but for example, a composition can be prepared by preparing a solution of the ring-opened product and a solution of the polymer, mixing them, and then removing the solvent. In this case, it is preferable to use a cast film because the handleability is improved. The blending ratio of the polymer to the ring-opened product is preferably 0.01 to 0.5 g, more preferably 0.05 to 0.1 g, based on 1 g of the polymer.

  In the present invention, the composition is prepared in a state where ultraviolet rays and visible light having a wavelength of less than 430 nm are shielded. This is because ultraviolet rays contained in ambient light and visible light having a wavelength of less than 430 nm convert the ring-opened body into a ring-closed body, so that correct measurement cannot be performed when the ring-opened body is used in a dosimeter. Although it is not possible to prepare a composition in an environment where light having a wavelength shorter than that of ultraviolet rays is significantly present, it is not stipulated, but for the purpose of the present invention, it is shorter than ultraviolet rays such as radiation. It is essential to prepare the composition without being affected by light of the wavelength. That is, it is essential to prepare the composition without being affected by light having a wavelength of less than 430 nm.

  Synthesis of the ring-opened compound and preparation of the composition can be carried out in an environment where ultraviolet rays and visible light having a wavelength of less than 430 nm are shielded, for example, in a light environment through a filter that shields the light rays. Alternatively, synthesis of the diarylethene is performed in an environment that does not block the light, and then the composition is prepared in an environment in which the light is shielded after sufficient exposure to visible light to completely diarylethene is ring-opened. May be. Further, the diarylethene was synthesized and the composition was prepared in an environment where the light beam was not shielded. After that, the diarylethene was fully exposed to visible light to completely open the diarylethene, and then the light beam was shielded. A composition may be prepared at

(2) Irradiation step In this step, the composition obtained in the previous step is irradiated with ultraviolet rays and visible light having a wavelength of less than 430 nm to give diarylethene represented by the formula 1b (hereinafter also referred to as “ring-closed body”). Generate. Examples of the radiation include electromagnetic radiation such as gamma rays and X-rays, and particle radiation such as α rays, β rays, and electron beams. The produced ring closure is a stable compound having absorption in the visible region (l> 400 nm) and does not thermally return to the original ring opening. As described above, this step is also performed under conditions that are not affected by light other than the irradiation radiation.

(3) Measurement step When the closed ring is irradiated with visible light having an absorption band, the photoexcited closed ring emits fluorescence and becomes a ground state. The amount of closed ring produced increases linearly depending on the radiation dose, and the amount produced can be detected as an increase in fluorescence intensity. For this reason, the radiation dose can be measured with high sensitivity by the composition of the present invention.

2. Dosimeter The radiation dosimeter of the present invention includes a composition containing diarylethene represented by Formula 1a housed in a container that shields ultraviolet rays and visible light having a wavelength of less than 430 nm. The composition containing diarylethene has already been described.

  The container which shields ultraviolet rays and visible light having a wavelength of less than 430 nm is not limited. When the composition is a solution, storing the solution in a container means that the solution is a container made of a filter that shields the light beam, a glass container or a polymer container coated with the filter, a container made of metal foil, a metal It is contained in a glass container or polymer container coated with a foil, a metal container or the like. Moreover, when the composition is a polymer composition, storing the polymer composition in a container includes covering the composition with the filter, metal foil, or the like. As described above, the shape and dimensions of the container are not limited, and may be appropriately determined according to the situation of use.

  A scintillation material having emission characteristics in the ultraviolet region may be disposed around the container. Examples of the material include BaFCl: Eu. The scintillation material generates fluorescence or phosphorescence in the ultraviolet region when irradiated with radiation. When these lights are absorbed by the ring-opened product of the diarylethene of the present invention, the formation of a ring-closed product having absorption in the visible region is induced as in the case of ultraviolet irradiation. Therefore, the radiation sensitivity of the dosimeter of the present invention is improved by the scintillation material.

Examples are shown below. The present invention is not limited by these examples.
[Reference Example 1]
Diarylethenes 2a, 3a, and 4a were synthesized according to the method described in the aforementioned non-patent literature. These compounds were purified by high performance liquid chromatography using a preparative silica gel column (Wakosil 5SIL, manufactured by Wako Pure Chemical Industries, Ltd.) using a mixed solvent of hexane: ethyl acetate = 8: 2 as a developing solvent. Subsequently, the compound was recrystallized using toluene and acetone to obtain pure compounds 2a, 3a, and 4a. These were colorless compounds. These are the most preferred compounds in the present invention. All operations were performed in an environment where ultraviolet rays and visible light having a wavelength of less than 430 nm were shielded.

  About the obtained compound, the fluorescence characteristic was measured with the fluorometer (the Hitachi, Ltd. make, F-2500). The solution containing the compound was added to a normal 1 cm fluorescent cell, and a trace amount of ultraviolet light contained in the excitation light was removed with an L-42 bandpass filter. Toluene and 1,4-dioxane were used as solvents. Compounds 2a and 3a in the toluene solution were non-fluorescent upon photoexcitation at 488 nm and 500 nm. Compound 4a in the toluene solution was non-fluorescent upon photoexcitation at 550 nm. Even when a 1,4-dioxane solution was used, no fluorescence was observed.

Example 1 Diarylethene / Solvent Composition 20 mg of each of compounds 2a, 3a, and 4a was completely dissolved in 4 mL of toluene and placed in a 20 mL glass bottle. Similarly, 20 mg of each of compounds 2a, 3a, and 4a was completely dissolved in 1,4-dioxane and placed in a 20 mL glass bottle. In the third irradiation room of the Institute of Radiation, Osaka Prefecture University, this solution was irradiated with gamma rays of cobalt 60 for 1 hour at 0.05 Gy, 0.1 Gy, 0.3 Gy, 0.5 Gy, 1 Gy, 1.5 Gy, 2 Gy. did.
Moreover, the toluene and 1, 4- dioxane solution which changed the quantity of the compound to 2 mg were prepared similarly, and each was put into a 20 mL glass bottle. In a state where the glass bottle was covered with aluminum foil and shielded from light, the bottle was irradiated with 10 Gy and 100 Gy of cobalt 60 gamma rays in an irradiation pool of Osaka Prefecture University.
All operations were performed in an environment where ultraviolet rays and visible light having a wavelength of less than 430 nm were shielded.

  When gamma rays were irradiated to the compound 2a in the toluene solution, 2a was converted to 2b (closed ring) by the gamma rays. The production of 2b can be confirmed by the fluorescence appearing by photoexcitation at 488 nm or 500 nm by measuring the fluorescence spectrum. It is clear from Non-Patent Documents 3 and 4 that this fluorescent substance has a chemical structure of 2b. The result is shown in FIG. Even when 1,4-dioxane was used instead of toluene, the production of 2b emitting fluorescence could be confirmed.

  FIG. 1 shows the result of measuring the fluorescence spectrum at 488 nm of excitation light after irradiating the compound 2a in the toluene solution with gamma rays. The fluorescence value changed from 0.05 Gy, and the fluorescence value increased as the amount of gamma ray irradiation increased. FIG. 2 shows the fluorescence intensity when detected at 530 nm. The fluorescence intensity increased with increasing radiation dose, and the relationship between the two changed linearly.

  A similar study was conducted for compound 3a in the toluene solution. FIG. 3 shows the result of detecting the fluorescence spectrum at excitation light of 488 nm at 530 nm after irradiation with gamma rays. The fluorescence value changed at 0.05 Gy, and the fluorescence value increased as the gamma ray irradiation amount increased. The fluorescence intensity increased with increasing radiation dose, and the relationship between the two changed linearly.

  The compound 4a having a thiophene ring as a substituent in a toluene solution was also examined. FIG. 4 shows the fluorescence intensity when the excitation light is 550 nm and detected at 586 nm. The fluorescence intensity increased with increasing gamma irradiation dose, and the relationship between the two changed linearly.

  The same measurement was performed in a 1,4-dioxane solution. Table 1 summarizes the numerical changes in the fluorescence measurement values based on these conditions.

  The minimum irradiation limit of the gamma ray irradiation dose is 0.05 Gy. The change in the fluorescence value was recognized with good reproducibility even at this irradiation amount, and it became clear that the radiation dose at the mGy level can be detected in the solution. In Table 1, crystalline cerium chloride heptahydrate was placed around a container containing a toluene solution of compound 2a and irradiated with 1 Gy of gamma rays. As a result, compared with the fluorescence value of 38.96 when nothing is arranged and the irradiation amount is 1 Gy, the fluorescence value is increased and the radiation sensitivity is slightly improved. It was revealed that cerium chloride heptahydrate has the effect of improving radiosensitivity because it converts gamma rays into ultraviolet rays.

[Example 2] Diarylethene / polymer composition In this example, compounds 2a to 4a were added to transparent polystyrene HF-77 (manufactured by Polystyrene Japan Co., Ltd.) to form a thin film. The procedure in the case of using Compound 2a as a representative example is shown. All operations were performed in an environment where ultraviolet rays and visible light having a wavelength of less than 430 nm were shielded.
950 mg of polystyrene HF-77 and 5 mL of toluene were placed in a glass bottle with a lid, and HF-77 was swollen over 2 days. In another glass bottle with a lid, 50 mg of compound 2a and 5 mL of toluene were placed and dissolved under a red LED light. The toluene solution was put into the glass bottle containing the swollen polystyrene and dissolved. Thereafter, all the solution was poured into a thin film former made of Teflon (registered trademark). It was covered with aluminum foil and black garbage bags and dried in the dark for 7 days. By this method, an HF-77 polystyrene thin film containing Compound 2a and having a thickness of about 0.5 mm, a width of 25 mm, and a length of 75 mm was prepared. This thin film was divided into three equal parts and divided into films having a thickness of about 0.5 mm, a width of 25 mm, and a length of 25 mm, and then dried at room temperature for 12 hours in a vacuum dryer.

  The thin film was sandwiched between two glass plates (100 mm × 100 mm). Two 0.2 mm aluminum plates were placed between the glass plates as spacers. A 0.8 kg copper plate (100 mm × 100 mm) was placed on the glass plate, 2.8 kg of the balance weight for the telescope was placed on the glass plate, and heated and compressed to 140 ° C. for 90 minutes in a vacuum dryer (10 mmHg). In this way, a flat and transparent HF-77 film was produced. Before irradiating with radiation, this film was divided into four equal parts by using a stylo cutter to obtain a film having a thickness of about 10 mm × 10 mm and a thickness of about 0.54 mm.

  A thin film was prepared in the same manner when compounds 3a and 4a were used. However, the amount of the compound was 100 mg, the dimensions of the thin film were about 10 mm × 10 mm, and the thickness was 0.27 mm.

  The fluorescence characteristics of the thin film were evaluated using a film measuring unit of a fluorometer (manufactured by Hitachi, Ltd., F-2500). In the measurement, a trace amount of ultraviolet light contained in the excitation light was removed with an L-42 bandpass filter. Furthermore, these thin films were put in a can shielded by an aluminum foil and irradiated with radiation. Cobalt 60 gamma rays were irradiated with 0.5 Gy, 1 Gy, 1.5 Gy, and 2 Gy for 1 hour in the third irradiation room of the Osaka Prefecture University Radiation Research Institute.

  When a polystyrene thin film containing 50 mg of compound 2a was used, the fluorescence value of the sample irradiated with radiation increased according to the dose compared to the case where radiation was not irradiated (0 Gy). This result shows that the closed ring (2b) is formed by gamma ray irradiation in the polymer thin film as in the experiment using the solution.

Two sheets of scintillation material BaFCl: Eu film (manufactured by Toshiba Materials, TB-80) were used to sandwich a polystyrene thin film containing compound 2a and irradiated with gamma rays. The result of taking out the polystyrene thin film and measuring the fluorescence spectrum is shown in FIG. Detection was performed at an excitation wavelength of 488 nm and a measurement wavelength of 530 nm. In the comparison of 1 Gy, when surrounded by a BaFCl: Eu film, the fluorescence value was 8.65 as shown in Table 2, and the fluorescence intensity increased about 3.5 times compared to the value 2.46 irradiated to the same 1 Gy direct. . This result shows that the amount of the fluorescent luminescent material generated is further increased according to the amount of gamma ray irradiation by surrounding the composition with a scintillation material such as BaFCl: Eu. Furthermore, the fluorescence value changed with 0.5 Gy of gamma ray irradiation. As shown in FIG. 6, it became clear that the fluorescence detection value at 530 nm increases with increasing gamma ray irradiation.

  Even when a polystyrene thin film containing 100 mg of compound 3a was used, the fluorescence value of the sample irradiated with radiation increased according to the dose compared to the case where radiation was not irradiated (0 Gy). FIG. 7 shows a change in fluorescence value when the thin film directly irradiated with gamma rays is excited at 488 nm. This result shows that a closed ring (3b) is produced by gamma irradiation.

  A scintillation material BaFCl: Eu film (manufactured by Toshiba Materials, TB-80) was used to sandwich a polystyrene thin film containing compound 3a and irradiated with gamma rays. FIG. 8 shows the result of taking out the polystyrene thin film and measuring the fluorescence spectrum. Detection was performed at an excitation wavelength of 488 nm and a measurement wavelength of 530 nm. In the comparison of 2Gy, the fluorescence value was 4.89 when surrounded by a BaFCl: Eu film, and the fluorescence intensity increased about 1.2 times compared to the value 4.21 irradiated to the same 2Gy direct.

Table 2 summarizes the results of changes in fluorescence intensity in the thin film. Table 2 shows the addition amount of the compound, the irradiation amount, the radiation conditions, and the measurement results. "Direct" indicates that the film was irradiated with gamma rays without placing anything around the polystyrene thin film. “In a BaFCl: Eu film” indicates that measurement was performed by sandwiching a polystyrene thin film between two MB-80 films manufactured by Toshiba Materials. “BaFCl: Eu powder” indicates that about 16 g of BaFCl: Eu powder was put in a capsule case and gamma rays were irradiated in a state where a polystyrene thin film sealed with polyethylene was put in the powder. “CaWO ₄ powder” indicates that about 15 g of CaWO ₄ powder was put in a capsule case and a polystyrene thin film sealed with polyethylene was put in the powder and gamma rays were irradiated. Even in the case of using CaWO ₄ powder, an increase in fluorescence intensity was observed as in the case of using a Toshiba material BaFCl: Eu film.

As can be seen from FIGS. 2, 3, and 4 showing the results in the solution, and FIG. 6 showing the results of the polystyrene thin film, the fluorescence intensity increases linearly according to the gamma irradiation dose.
That is, the composition used in the present invention has a feature that the fluorescence intensity increases according to the dose of gamma rays. Therefore, the present invention is useful as a radiation dosimeter capable of measuring an irradiation dose.

Claims (5)

Preparing a composition comprising diarylethene represented by formula 1a under ultraviolet light and visible light shielding having a wavelength of less than 430 nm;

(Wherein R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms,
R ³ and R ⁴ are each independently an aryl group having 5 to 10 carbon atoms,
R ⁵ and R ⁶ are each independently an alkyl group having 1 to 3 carbon atoms,
n is independently 0 or 1,
-(CY) m- represents an alicyclic skeleton, Y is a hydrogen atom or a halogen atom, and m is an integer of 5 to 7.
Irradiating the composition with ultraviolet rays and a visible light shield having a wavelength of less than 430 nm to produce a diarylethene represented by Formula 1b;

(Wherein R ^{1 to} R ⁶ , Y, n, and m are defined as above)
And
Measuring the fluorescence intensity of the composition obtained in the step,
A method for measuring radiation dose, including:   The method according to claim 1, wherein Y is a halogen atom, n is 0, and m is 5. The method according to claim 1 or 2, wherein R ³ and R ⁴ are a phenyl group or a thienyl group. A radiation dosimeter comprising a composition containing diarylethene represented by formula 1a, housed in a container that blocks ultraviolet rays and visible light having a wavelength of less than 430 nm.

(Wherein R ^{1 to} R ⁶ , Y, n, and m are defined as above)   The radiation dosimeter according to claim 4, further comprising a scintillation material having a light emission characteristic in an ultraviolet region, which is disposed around the container.

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