JP2009265033A - Color dosimeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color dosimeter for developing a color by the irradiation of radiation of several Gy, having high sensitivity, capable of developing a color in real time, and not preventing observation even in X-ray fluoroscopy. <P>SOLUTION: In this color dosimeter, a polymer 1 including at least an organic halogenide or having an organic halogenide in a skeleton has a contact with a polymer 2 that includes a pH indicator, not containing organic halogenides, and not having an organic halogenide in the skeleton. Preferably, the polymer 1 has a contact with the polymer 2 in a piled state, in the form of at least two or more layers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a color dosimeter.

  The radiation referred to in the present invention refers to beta rays (electron beams) that are charged particles, and gamma rays and X-rays that are electromagnetic waves, and these radiations are widely used in the medical field. Specifically, diagnostic methods such as X-ray photography are included in addition to peripheral areas such as sterilization treatment of medical instruments and medical tools. Recently, it has come to be actively used as an indirect or direct treatment method for the human body, such as irradiation of blood for transfusion or cancer treatment. It is said that this trend will become even higher in the future.

  One reason is the reduction of physical burden on the patient. In the past, for diseases that could only be dealt with by surgery or for diseases that were difficult to perform, surgery could be taken or only symptomatic treatment was possible. However, it should be handled in a way that greatly reduces the load on the human body, such as computed tomography (CT) using X-rays and catheter surgery using continuous X-ray imaging (interventional radiology, hereinafter IVR). Became possible.

  However, due to radiation exposure to patients, some patients have radiation skin damage due to excessive irradiation (for example, Non-Patent Document 1). Based on this situation, there is an urgent need to create an environment that will not cause skin damage to medical practices that use radiation, and to be able to take appropriate measures in the event of a failure.

  The following methods are used in the conventionally used radiation measurement methods. Examples include ionization chambers, proportional counters, GM counters, scintillation counters, semiconductor detectors, thermofluorescence dosimeters, fluorescent glass dosimeters, photographic films, and color dosimeters. These measurement methods require special devices, and it is difficult to specify the irradiation range depending on the situation, and it is difficult to use in a medical field where the irradiation dose varies.

  Recently, color dosimeters have attracted attention. A color dosimeter visually indicates the presence of energy that cannot be captured by the human eye, such as radiation such as beta rays (electron rays), gamma rays, and X-rays, using chemical and physical reactions. It can be detected.

  A typical color dosimeter uses the following three reactions. That is, (1) radiolysis reaction of organic halide, (2) radiation polymerization reaction, and (3) photochromic reaction utilizing scintillation. Each will be described in detail below.

(1) Radiolysis reaction of organic halide This reaction uses acid-generated hydrogen halide generated by radiolysis of an organic halide. Irradiation generates hydrogen halide and increases the hydrogen ion concentration in the dosimeter. At this time, a color change reaction occurs by combining a pH indicator. The irradiation dose is quantified using this discoloration state.

  One of the materials specifically used is a combination of leuco dye and polyvinyl chloride (for example, Patent Document 1). This method changes color when the radiation dose is 5,000 to 25,000 Gy or more. Further, since the acid generated is volatile, the environment setting becomes strict in order to obtain good reproducibility.

(2) Radiation polymerization reaction This reaction utilizes radiation polymerization of a diacetylene compound having two alkynyl groups in one molecule (for example, Patent Document 2). Since this type of compound spontaneously crystallizes so that alkynyl groups are stacked by simply applying a solution, a chain polymerization reaction occurs due to external stimuli such as X-rays. As a result, a compound in which π-electron conjugation is developed is generated, and visibility is developed because the product has absorption in the visible light region.

  Although this technique shows sensitivity even in a relatively low dose region of about 100 Gy, it takes less than 1 hour to complete the reaction, so it is inferior in immediacy.

(3) Photochromic reaction using scintillation This reaction uses a diarylethene compound exhibiting photochromic properties as a detection material (for example, Patent Document 3).

  In general, photochromic materials do not exhibit chromic properties in radiation chemical reactions. Therefore, the feature is that the radiation energy is converted into light energy causing photochromism by a scintillator.

Since an inorganic scintillator is necessary for increasing the sensitivity of this method, there is a problem of image quality degradation when using an X-ray fluoroscopic image such as IVR. In addition, since this reaction is reversed by visible light, it is necessary to strictly control the storage state after the reaction.
Japanese Patent Publication No. 06-072929 JP 2000-241548 A JP 2005-082507 A N. Nakamura, Kunihiko Morosumi, Atsuhiko Togashi, “Clinical IVR and Exposure Protection”, Medical Science, Inc., Tokyo (2004)

As described above, conventionally, there has been no color dosimeter that produces color in real time with high reproducibility by radiation irradiation in a low dose region of about several Gy and does not hinder observation even in X-ray fluoroscopy like IVR.
The present invention has been made in view of such background art, and aims to provide a highly sensitive color dosimeter.

  A color dosimeter that solves the above-described problems includes at least an organic halide or a polymer 1 having an organic halide as a skeleton and a pH indicator, but does not contain an organic halide and does not contain an organic halogen. The polymer 2 which does not have a chemical compound in the skeleton is in contact with it.

  The polymer 1 and the polymer 2 may be stacked and in contact with each other in at least two layers, or the polymer 1 may be dispersed in the polymer 2. Further, a structure in which the polymer 2 is dispersed in the polymer 1 may be formed.

The present invention can provide a highly sensitive color dosimeter.
In the present invention, the acid generated by irradiating the organic halide of polymer 1 and the pH indicator for detecting the acid generated by polymer 2 are separated into separate layers to form a structure in contact with each other. As a result, the frequency at which the acid (hydrogen ion) reacts with the pH indicator is increased, and as a result, an irradiation amount of several Gy is detected. Therefore, it is possible to provide a color dosimeter that develops color in real time with irradiation at a dose of 1/100 or less than that of the prior art and that does not hinder observation even in X-ray fluoroscopy like IVR.

Hereinafter, the present invention will be described in detail.
The color dosimeter according to the present invention contains at least an organic halide or a polymer 1 having an organic halide as a skeleton and a pH indicator, but does not contain an organic halide and contains an organic halide. The polymer 2 which does not have in the skeleton is in contact.

  The present invention is a high-sensitivity color dosimeter in which the above-described polymer 1 and polymer 2 are separated and have a structure in which the polymers 1 and 2 are in contact with each other, thereby discoloring even at a low dose of 1/100 or less.

  The present invention utilizes the radiolysis reaction of organic halides in a color dosimeter. In the prior art, since the organic halide and the pH indicator for detecting the acid generated by radiation irradiation are in the same layer, the concentration of the generated acid (particularly hydrogen ions) is in the entire layer. It is uniform. Therefore, little acid diffusion occurs.

  On the other hand, the present invention is characterized in that a layer in which an acid is generated by a radiolysis reaction and a layer in which the acid is detected are separated and in contact with each other. In the interface formed in the present invention, the polymer 1 and the polymer 2 may be in contact with each other stacked in at least two layers. The polymer 1 may be dispersed in the polymer 2, or the polymer 2 may be dispersed in the polymer 1.

  The radiation sensitivity that can be detected is about several Gy even in the most basic configuration, even in the case of forming a two-layer structure in which a layer in which an acid is generated by a radiolysis reaction and a layer for detecting the acid are separated. In addition, it has been confirmed that the sensitivity is improved by two orders of magnitude or more even when compared with the one-layer structure.

  In the photoresist field, a similar technique is used as a technique for increasing the sensitivity of a resist material (for example, Document A: Leo Schlegel, Takami Ueno, Nobuaki Hayashi, Takao Iwayanagi, Japan Journal of Apy. , Pp 3132-3137.). According to this, when the photoacid generator is uniformly dissolved and dispersed in the resist material, the movement distance of the generated acid is estimated to be about 5 nm although it depends on the process conditions. This is because when the generated acid is evenly distributed, a concentration gradient does not occur, and the diffusion distance does not increase.

  On the other hand, when the resist material layer and the acid-generating layer are separated from each other, the distance moved by the generated acid is reported to the above-mentioned document A that it may exceed 2000 nm depending on the process conditions. Has been.

  The mechanism is attributed to the structure in which the site where the acid is generated is separated from the site where the acid is not present. After resist exposure, a large difference occurs in the concentration of hydrogen ions contained in each layer. Thermodynamic action occurs in the direction that makes the difference uniform between substances where the difference in concentration occurs (Le Chatelier's law of equilibrium), and hydrogen ions diffuse according to Fick's law. As a result, the diffusion distance increases dramatically. In the present invention, this principle is applied.

  The color dosimeter of this invention can be used by the method according to the aspect. Hereinafter, embodiments of the color dosimeter of the present invention will be described with reference to FIGS. 1 to 4, but are not limited thereto. FIG.1 and FIG.2 is sectional drawing which shows typically the example of the laminated constitution of the laminated body in the color dosimeter of this invention. FIG. 3 shows that, in the color dosimeter of the present invention, at least the polymer 1 containing an organic halide or having an organic halide in the skeleton contains a pH indicator, but does not contain an organic halide, but an organic halide. It is sectional drawing which shows typically the example of the layer structure disperse | distributed in the polymer 2 which does not have in a frame | skeleton. FIG. 4 is a cross-sectional view schematically showing an example of a layer configuration in which the polymer 2 is dispersed in the polymer 1 in the color dosimeter of the present invention.

[Laminate]
The laminate includes at least the polymer 1 containing an organic halide or having an organic halide in the skeleton and a pH indicator, but does not contain an organic halide and does not have an organic halide in the skeleton. The polymer 2 has at least a contact structure.

  In the example of the layer structure of the laminate shown in FIG. 1, the polymer 1 and the polymer 2 constitute independent layers, the respective surfaces are brought into close contact with each other, and bonded to form one laminate. Have created. In FIG. 2, a plurality of layers are stacked so as to be alternately stacked.

  Since the acid generated from the polymer 1 upon irradiation with radiation is volatile, it is desirable that the polymer 2 sandwich the polymer 1. Thereby, the volatilization effect of the acid can be suppressed, and the reproducibility can be improved.

  The polymer 1 containing an organic halide is composed of a mixture of the polymer 1a and the organic halide. The organic halide contained in the polymer 1 may have one or more halogen atoms in the aliphatic hydrocarbon compound or one or more halogen atoms in the aromatic hydrocarbon compound. The halogen atom may be any of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, but each may have one or more.

  Specific examples of organic halides include aliphatic tetrahydrocarbons such as carbon tetrabromide (hereinafter referred to as TBC), 1,2,3,4,5,6-hexachlorohexane, tribromomethylphenyl sulfone (hereinafter referred to as TBS), and the like. There is. Examples of aromatic hydrocarbons include 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1-bromonaphthalene and the like.

As the polymer 1a constituting the mixture of the polymer 1a and the organic halide, polystyrene (PS), alkyd resin, modified polyester, or the like is used.
Next, the polymer 1 having an organic halide in the skeleton may be either a polymer having a halogen atom in the main chain or a polymer having a halogen atom in the side chain. Examples of the polymer having a halogen atom in the main chain include polyvinyl chloride (PVC), polyvinylidene chloride, and polyvinylidene fluoride (PVDF). Moreover, a copolymer may be sufficient if the monomer unit which has a halogen atom in a principal chain or a side chain exists. An example is a copolymer of vinyl chloride and vinyl acetate.

Next, polymer 2 which does not contain an organic halide and does not have an organic halide in its skeleton is used.
As the pH indicator, methyl yellow (hereinafter referred to as MY), bromcresol green (hereinafter referred to as BCG) or the like is used.

  As a method for preparing the laminate, the polymer 1 and the polymer 2 may be prepared separately and bonded by heating. Further, after the polymer 1 or polymer 2 layer is formed, the polymer 2 or polymer 1 layer may be formed thereon. As a layer forming method, it can be molded using various known techniques such as a casting method, a spin coating method, a bar coater method, and a die casting method. The thickness of the film is not particularly limited as long as it brings out the characteristics of a color dosimeter, but a range of 0.01 to 1 mm is preferable.

  When radiation is applied to the laminate that has been molded as described above, the color tone changes according to the radiation dose. The absorption dose of radiation can be estimated by measuring the absorption / transmission spectrum or reflection spectrum and measuring the amount of change in absorbance, transmittance or reflectance.

  The color dosimeter of the present invention may be used in combination with an ultraviolet absorber in order to avoid coloring due to ambient light such as room light. Specifically, the ultraviolet absorber may be contained as one component of the composition, or an ultraviolet cut layer may be formed on the surface of a color dosimeter prepared from the composition.

[Dispersion]
As shown in FIGS. 3 and 4, the dispersion includes an organic halide or the polymer 1 having an organic halide as a skeleton contains a pH indicator, but does not contain an organic halide. In addition, it refers to a form in which the organic halide is not dispersed in the polymer 2 or a form in which the polymer 2 is dispersed in the polymer 1.

Each of the polymer 1 and the polymer 2 may be the same as the laminate.
As a method for preparing the dispersion, the polymer 1 and the polymer 2 may be vigorously stirred in a molten state, or the solvent may be removed by mixing the polymer 1 solution and the polymer 2 solution. . The mixed solution may be a heterogeneous solution system such as a micelle or emulsion, but may be a homogeneous solution system. However, in the case of the latter homogeneous solution system, in the process of removing the solvent, it is necessary to phase-separate each polymer so as to hold each component.

  When the dispersion formed as described above is irradiated with radiation, the color tone changes according to the radiation dose. By measuring the absorption / transmission spectrum or the reflection spectrum and measuring the amount of change in absorbance, transmittance or reflectance, the radiation dose can be measured.

  The color dosimeter of the present invention may be used in combination with an ultraviolet absorber in order to avoid coloring due to ambient light such as room light. Specifically, the ultraviolet absorber may be contained as one component of the composition, or an ultraviolet cut layer may be formed on the surface of a color dosimeter prepared from the composition.

Hereinafter, the present invention will be specifically described with reference to examples.
Examples 1 and 2
Radiation was irradiated to a film in which a polymer 1 containing an organic halide and a polymer containing a pH indicator but not containing an organic halide and having no organic halide in the skeleton had a laminated structure. The irradiated radiation is X-rays, and the irradiation amount is 5 Gy (tube voltage 5 keV, tube current 20 mA). At this time, the colored state was visually evaluated, and further, left for 48 hours in a dark place, and then visually evaluated.

The above results are shown in Table 1.
In addition, the preparation method of a film is as follows. The raw materials of the polymer 1 layer and the polymer 2 layer were separately applied on a PET sheet using an applicator set to a film thickness of 0.3 mm. Next, after removing the solvent over 30 minutes on a hot plate heated to 80 ° C., an evaluation film was prepared by pasting each layer so that the layers face each other.

(note)
1) Toluene was used as the solvent.
2) 1.0 g of TBC (carbon tetrabromide) was added.
3) 0.1 mL of MY (methyl yellow) 0.006 g / L (toluene solution) was added.
4) 1.0 g of TBS (tribromomethylphenyl sulfone) was added.

  From the results in Table 1, it can be seen that the film is discolored by irradiation with X-ray 5Gy and exhibits high sensitivity performance as a color dosimeter, and further, after leaving for 48 hours in a dark place, no change in color is observed after 48 hours after irradiation.

Examples 3 to 4
Radiation was irradiated to a film in which a polymer 1 having an organic halide in the skeleton and a polymer containing a pH indicator but not containing an organic halide and having no organic halide in the skeleton had a laminated structure.

  The irradiated radiation is X-rays, and the irradiation amount is 5 Gy (tube voltage 5 keV, tube current 20 mA). At this time, the colored state was visually evaluated, and further, visually evaluated after being left in a dark place for 48 hours.

The above results are shown in Table 2.
In addition, the preparation method of a film is as follows. The raw materials of the polymer 1 layer and the polymer 2 layer were separately applied on a PET sheet using an applicator set to a film thickness of 0.3 mm. Next, after removing the solvent over 30 minutes on a hot plate heated to 80 ° C., an evaluation film was prepared by pasting each layer so that the layers face each other.

(note)
1) Vinyl chloride-vinyl acetate copolymer. The solvent is butyl acetate.
2) Toluene was used as the solvent.
3) 0.1 mL of MY (methyl yellow) 0.006 g / L (toluene solution) was added.
4) 0.1 mL of BCG (bromocresol green) 0.004 g / L (toluene solution) was added.

  From the results of Table 2, it can be seen that the film shows sensitivity performance as a color dosimeter that changes color when irradiated with X-rays 5 Gy, and that it does not change after standing for 48 hours in a dark place.

Comparative Examples 1 to 3
Three points of 100 g of a butyl acetate solution of polyvinyl chloride as an organic halide (concentration 37 wt%) were prepared, and 0.04 g, 0.40 g, and 0.80 g of methyl yellow as a pH indicator were dissolved separately. Each of these solutions was coated on a PET film with a 0.3 mm applicator, and the solvent was removed on a hot plate at 80 ° C. for 30 minutes to prepare a film sample. Two samples of each were prepared, and X-rays were irradiated with 5 Gy and 5000 Gy (tube voltage 5 keV, tube current 20 mA). The results are shown in Table 3.

  From the results in Table 3, it can be seen that the color development reaction of the pH indicator utilizing the radiolysis reaction of polyvinyl chloride, which is an organic halide, requires irradiation of about 5000 Gy. Therefore, it is impossible to detect radiation irradiation of about several Gy.

Comparative Example 4
0.19 g of 10,12-pentacosadiynoic acid was dissolved in 2 mL of toluene. 2 μL of this was dropped onto glossy inkjet paper, and the solvent was removed over 30 minutes on a hot plate at 80 ° C. to prepare a film sample.

  This sample was irradiated with X-rays at 5 Gy (tube voltage 5 keV, tube current 20 mA). At this time, the colored state was visually evaluated, and further, left for 48 hours in a dark place, and then visually evaluated. The results are shown in Table 4. As can be seen from the results in Table 4, discoloration did not end even after irradiation, suggesting that a dose with excellent immediacy cannot be evaluated.

  The color dosimeter of the present invention can measure X-rays with high sensitivity and color in real time, and does not hinder observation even in X-ray fluoroscopy, and can be used as an over-irradiation prevention detection label such as IVR and CT.

It is sectional drawing which shows typically one embodiment of the layer structure of the laminated body as a color dosimeter of this invention. It is sectional drawing which shows typically the other embodiment of the laminated constitution of the laminated body as a color dosimeter of this invention. It is sectional drawing which shows typically the other embodiment of the layer structure of the dispersion body as a color dosimeter of this invention. It is sectional drawing which shows typically the other embodiment of the layer structure of the dispersion body as a color dosimeter of this invention.

Explanation of symbols

1 Polymer 1
2 Polymer 2

Claims (2)

  At least the polymer 1 containing an organic halide or having an organic halide in the skeleton is in contact with the polymer 2 containing a pH indicator but not containing an organic halide and having no organic halide in the skeleton. A color dosimeter characterized by   The color dosimeter according to claim 1, wherein the polymer 1 and the polymer 2 are in contact with each other stacked in at least two layers.

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