JP2005091221A - Radiological image convertor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiological image convertor excellent in vibration resistance and impact resistance and capable of giving a radiological image with high quality. <P>SOLUTION: The radiological image convertor comprises a moisture impermeable rigid sheet having a phosphor layer formed on one surface thereof by a vapor deposition method and a second moisture impermeable sheet, both of which sheets are opposed to each other with the phosphor layer being disposed inside, with side faces being sealed moisture-impermeably. At least one of the two moisture impermeable sheets is transparent. A vibration absorbing material is attached to at least one surface of the moisture impermeable sheets. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radiation image converter in which a phosphor layer formed by vapor deposition is sandwiched between two non-moisture permeable rigid substrates.

  When irradiated with radiation such as X-rays, it absorbs and accumulates part of the radiation energy, and then emits light according to the accumulated radiation energy when irradiated with electromagnetic waves (excitation light) such as visible light and infrared rays. Using a stimulable phosphor having properties (such as a stimulable phosphor exhibiting stimulated emission), a planar radiation image converter (or radiation image conversion panel) containing the stimulable phosphor is subjected to After the radiation image information of the subject is once accumulated and recorded by irradiating the radiation that has passed through the specimen or emitted from the subject, the converter is scanned with excitation light such as laser light and sequentially emitted as emitted light, A radiation image information recording / reproducing method is widely used, which comprises photoelectrically reading the emitted light to obtain an image signal. The radiation image converter that has finished reading is erased for the remaining radiation energy, and is then prepared and used repeatedly for the next imaging.

  The radiation image converter used in the radiation image information recording / reproducing method includes, as a basic structure, a support and a storage phosphor layer provided thereon. In addition, a protective layer is usually provided on the upper surface of the stimulable phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact. Yes.

  The phosphor layer includes a stimulable phosphor and a binder containing and supporting the phosphor in a dispersed state, and does not contain a binder formed by a vapor deposition method or a sintering method. Those composed only of collections are known.

  Regarding the radiation image information reading apparatus used in the above-described radiation image information recording / reproducing method (radiation image conversion method), as an excitation light source, there are a number of line light sources that irradiate the radiation image converter in a linear manner, and many detection means The photoelectric conversion elements are linearly arranged, a line sensor for detecting emitted light generated linearly from the radiation image converter, and a line light source and a line sensor or radiation image converter are substantially defined as the linear direction. There has been proposed a configuration of a line scan reading system provided with a conveying means that moves in an orthogonal direction. According to the line scan reading method using this line light source and line sensor, since reading is performed by linear excitation and linear detection, the reading time of emitted light is shortened, the apparatus is miniaturized, and the cost is reduced. be able to.

  In the line scan reading method, in order to increase the light collection efficiency of emitted light, an image forming lens such as a gradient index lens array is used to emit light emitted from the radiation image converter onto the line sensor through the image forming lens. The image is formed. Such an imaging lens has a narrow allowable range (a range in which an imaging relationship is established, that is, a depth of focus) with respect to a decrease in the horizontality of the radiation image converter. The amount of light will decrease. Therefore, when the horizontality of the radiation image converter is low, the image quality is degraded.

  On the other hand, when the phosphor layer is easily changed (deteriorated) due to humidity, such as a phosphor layer formed by vapor deposition, a moisture-resistant protective layer is formed on both sides of the phosphor layer. It is desirable to provide a support or the like.

  Patent Document 1 discloses a radiation image converter in which a phosphor layer is sandwiched between a non-moisture permeable rigid substrate and a non-moisture permeable rigid protective plate arranged on both sides thereof. Specifically, glass and metal are described as the moisture-impermeable rigid substrate.

JP-A-4-76500

  In the radiation image information reading apparatus and the radiation image information recording / reproducing apparatus further provided with image information recording means, the radiation image converter is read in a horizontal state or a vertical state. In particular, the latter miniaturized apparatus often employs a method of recording image information by irradiating radiation from one side of the radiation image converter and reading it from the other side. In order not to block light or emitted light, the radiation image converter is supported only from both ends along the longitudinal direction, so that the horizontality of the radiation image converter tends to be impaired.

  If a rigid sheet is attached to the opposite side of the protective layer of the phosphor layer (usually a transparent glass plate) in order to improve the level, radiation will be emitted from the rigid sheet side, so image quality will be reduced. Therefore, it is desirable that the rigid sheet has as little radiation absorption as possible. As such a rigid sheet, a rigid sheet made of an organic material in which a reinforcing material such as a carbon fiber reinforced plastic (CFRP) sheet is embedded is suitable.

  A radiation image converter using a phosphor sheet in which a phosphor layer is formed on a glass plate by vapor deposition may be damaged by various external impacts in the radiation image recording and reproducing process. . Further, in the process of reading a radiation image using the above-described radiation image information reading apparatus, vibration generated from the apparatus is easily transmitted to the radiation image converter. In this case, the stability of image reading and the radiation obtained It has been found by the inventor that undesirable effects can appear on the image quality of the image.

  In addition, when the protective layer is provided with rigidity in order to improve the horizontality, a rigid sheet is not required, but in order to provide the radiation image converter with moisture resistance, the phosphor layer glass plate and It is desirable to cover the opposite surface with a rigid sheet that is moisture resistant and has little radiation absorption.

  As a result of examining these problems and requirements, the present inventor can solve the problem of damage and destruction of the radiation image converter by attaching a vibration absorbing material to the rigid sheet surface of the radiation image converter. It has been found that the instability of the radiation image reading process due to the influence of vibration generated by the radiation image reading apparatus and the deterioration of the image quality of the obtained radiation image can be prevented.

  An object of the present invention is to provide a radiation image converter which is excellent in moisture resistance, vibration resistance and impact resistance and which can provide a high-quality radiation image.

  In the present invention, a non-moisture permeable rigid sheet having a phosphor layer formed on one surface by a vapor deposition method and another non-moisture permeable rigid sheet are face-to-face with the phosphor layer facing inside. In a radiation image converter that is non-breathably sealed and at least one of the non-breathable rigid sheets is transparent, vibrates on at least one surface of at least one of the plurality of non-breathable rigid sheets. The radiation image converter is characterized in that an absorptive material is attached.

  In the radiation image converter of the present invention, the vibration-absorbing material is attached to the surface of a rigid sheet, such as CFRP, whose main constituent material is an organic resin material that mainly functions as a support. Remarkably enhances shock resistance, reduces the occurrence of damage and destruction of the radiation image converter, and is less susceptible to vibrations generated by the playback device during radiation image playback operations. Can be obtained. Furthermore, the radiation image converter of the present invention can improve moisture resistance by using a metal thin film in combination, has a small self-weight deflection, excellent horizontality, and a rigid sheet or phosphor mainly composed of an organic resin material. Even if radiation is irradiated from the layer side, radiation absorption by a rigid sheet or vibration absorbing material mainly composed of an organic resin material is small, so that a high-quality radiation image can be provided.

  Therefore, the radiation image converter of the present invention is suitable for a line scan type reading apparatus. Particularly, it is advantageously used for a radiation image information recording / reproducing apparatus with a small-sized radiation image converter that employs a method of irradiating radiation from one side of the radiation image converter and reading from the other side. Can do.

A preferred embodiment of the radiation image converter of the present invention will be described next.
(1) The non-moisture permeable rigid sheet on which the phosphor layer is formed is transparent, and the vibration absorbing material is attached to the surface of another non-moisture permeable rigid sheet.
(2) The non-breathable rigid sheet to which the vibration absorbing material is attached is a carbon fiber reinforced resin molded sheet (CFRP).
(3) A vibration-absorbing material is attached to the outer surface of another non-moisture permeable rigid sheet.
(4) The vibration-absorbing material is attached to the inner surface of another non-breathable rigid sheet.
(5) The vibration-absorbing material is attached to the outer surface of the non-moisture permeable rigid sheet on which the phosphor layer is formed, and another non-moisture permeable rigid sheet is transparent.
(6) A vibration-absorbing material is attached to the outer surface of another moisture-impermeable rigid sheet.

  The vibration-absorbing material itself used for improving the vibration resistance and impact resistance of the radiation image converter of the present invention is obtained by immediately converting vibration energy or impact energy applied to the material into thermal energy. It is already known as a material having a function of quickly suppressing vibration and impact. Typical examples of the material include norbornene rubber (norsolex), polyurethane low hardness rubber (sorbosein), silicone gel (α gel), silicone gel (β gel), and the dynamic tan δ at 20 ° C. is Usually, it is in the range of 1.2 to 1.7. In the radiation image converter of the present invention, the vibration absorbing material is used as a film, a covering layer, or a packed layer.

  In order to improve the moisture resistance of the radiation image converter of the present invention in addition to the improvement of vibration resistance and impact resistance, at least part of the surface of the phosphor layer of the radiation image converter is directly or indirectly applied. It is desirable to cover with a metal film (metal foil or metal vapor deposition layer) whose moisture permeability is below the measurement limit.

Here, that the moisture permeability is below the measurement limit means that the moisture permeability at 25 ° C. is 0.001 g / m ² or less. The X-ray absorption rate of the metal thin film is generally 10% or less. Examples of the metal thin film satisfying such conditions include a thin film made of aluminum, a magnesium alloy, beryllium, or the like, and an aluminum thin film is particularly preferable. The thickness of the metal thin film is generally in the range of 0.1 to 700 μm. When an aluminum thin film is used, it is preferable that the aluminum vapor deposition film has a thickness of 0.1 to 10 μm, and the aluminum foil has a thickness of 10 to 350 μm.

  The phosphor layer is provided in contact with a transparent rigid sheet such as a glass plate (provided on the reading side of the radiation image converter and functions as a protective sheet) and inside the rigid transparent sheet. It is preferable that a filling resin layer is provided on the surface of the phosphor layer opposite to the transparent rigid sheet so as to cover the phosphor layer. A rigid frame spacer (moisture-resistant sealing member or moisture-resistant adhesive) is disposed between the transparent rigid sheet and the opposite rigid sheet mainly composed of an organic resin material, and around the phosphor layer. It is preferable that a sealing portion with an agent is provided.

  Next, the structure of the radiation image converter of this invention is demonstrated, referring an accompanying drawing. FIG. 1 is a schematic sectional view showing a configuration example of a radiation image converter according to the present invention. In FIG. 1, the radiation image converter includes a glass plate 11, a phosphor layer 12, a filling resin layer 13, a rigid sheet 14 mainly composed of an organic resin material, a frame spacer 15, and a vibration absorbing material 16a. Is done.

  Since the glass plate 11 is normally the side on which the radiation image is read, it is transparent, has a high transmittance with respect to excitation light and emitted light, is excellent in air tightness, and has a very low moisture permeability. It has properties (non-moisture permeable). Moreover, it is desirable to have high parallel flatness.

  The phosphor layer 12 is a layer made of a stimulable phosphor formed by a vapor deposition method, and is provided in contact with the glass plate 11 and leaving a peripheral portion inside thereof. The reason why the phosphor layer 12 is in contact with the glass plate 11 is to keep the distance from the imaging lens to the surface of the phosphor layer 12 within an allowable range during reading as described above.

  The filling resin layer 13 is provided so as to cover the phosphor layer 12. The filling resin layer 13 is provided in order to maintain high plane accuracy in the radiation image converter, particularly the glass plate 11 and the phosphor layer 12. Usually, it is made of a material having a lower density and lighter than the rigid sheet 14 whose main constituent material is an organic resin material.

  A rigid sheet 14 made of an organic resin material as a main constituent material such as CFRP has rigidity in order to keep the radiation image converter horizontal. Further, the rigid sheet 14 is usually on the side irradiated with radiation, and thus is made of an organic material with little radiation absorption.

  The frame spacer 15 is provided between the glass plate 11 and the rigid sheet 14 and in the periphery of the phosphor layer 12 and the filling resin layer 13 in order to prevent moisture from entering from the side surface. The frame spacer is desirably rigid and impermeable to moisture, but may be formed from a normal adhesive.

  In FIG. 1, the vibration-absorbing material 16a, which is a characteristic requirement of the present invention, is provided on the outer surface (the surface opposite to the phosphor layer) of the rigid sheet 14 having an organic resin material as a main constituent material. Yes. The vibration absorbing material may be a laminate with a metal thin film. Alternatively, the phosphor layer may be covered with a metal thin film.

2 to 4 are schematic cross-sectional views each showing another configuration example of the radiation image converter of the present invention in the case of having a rigid sheet mainly composed of an organic resin material.
In FIG. 2, the radiation image converter includes a glass plate 11, a phosphor layer 12, a filling resin layer 13, a rigid sheet 14 composed mainly of an organic resin material, a frame spacer 15, and a vibration absorbing material 16b. Is done. The vibration-absorbing material 16b is integrated with the outer surface of the rigid sheet 14 mainly composed of an organic resin material and the peripheral side surface of the radiation image converter (that is, the entire surface of the radiation image converter excluding the surface of the glass plate 11). Is provided. The vibration absorbing material may be a laminate with a metal thin film. The phosphor layer may be coated with a metal thin film.

  In FIG. 3, the radiation image converter includes a glass plate 11, a phosphor layer 12, a filling resin layer 13, a rigid sheet 14 mainly composed of an organic resin material, and a vibration absorbing material 16c. The vibration-absorbing material 16c is provided integrally over the outer surface of the rigid sheet 14, the peripheral side surface of the radiation image converter, and the outer surface edge of the glass plate 11. The vibration absorbing material may be a laminate with a metal thin film. The phosphor layer may be coated with a metal thin film.

  As shown in FIGS. 2 and 3, the vibration absorbing material is also provided on the side surface of the radiation image converter to further improve the vibration resistance and impact resistance of the radiation image converter.

  In FIG. 4, the radiation image converter sequentially includes a glass plate 11, a phosphor layer 12, a filling resin layer 13, a vibration-absorbing material 16 d, a rigid sheet 14 mainly composed of an organic resin material, and a frame spacer 15. Composed. The vibration absorbing material 16 d is provided on the phosphor layer side surface of the rigid sheet 14. Thereby, the phosphor layer 12 has a structure confined in a sealed space composed of the glass plate 11, the frame spacer 15, and the vibration absorbing material 16d. The vibration absorbing material may be a laminate with a metal thin film. The phosphor layer may be coated with a metal thin film.

In the present invention, the radiation image converter is not limited to the illustrated configuration. For example, when the vibration-absorbing material is also provided on the side surface of the radiation image converter, it is not always necessary to provide the frame spacer. Alternatively, the phosphor layer may be provided on the entire surface of the glass plate. Further, the filling resin layer may not be provided, or a configuration in which various known auxiliary layers such as a light reflection layer and an undercoat layer are further provided may be used.
Alternatively, the phosphor layer may be laminated on a metal substrate, and the counterpart substrate may be a transparent substrate. In this case, the vibration-absorbing material is provided outside the metal substrate.

  Next, the method for producing the radiation image converter of the present invention will be described in more detail by taking as an example the case where the transparent rigid sheet is a glass plate and the phosphor is a storage phosphor.

The elastic modulus of the glass plate directly supporting the phosphor is preferably 9.8 × 10 ³ MPa or more, more preferably 1.96 × 10 ^{4 to} 9.8 × 10 ⁶ MPa. Further, it is desirable that the glass plate is transparent (having high transmittance with respect to excitation light and emitted light), has high parallel flatness, is excellent in airtightness, and has low moisture permeability. A typical glass plate that satisfies such conditions is a glass sheet (silicate glass sheet). Specifically, Cornig Japan Co., Ltd. # 1737 0.5t, # 1737 0.7t, EAGLE 2000 0.63t, Central Glass Co., Ltd. FL0.7, 0.85, 1.0; Nippon Sheet Glass Co., Ltd. UFFO.40 0.50, 0.55, 0.70; and Asahi Glass Co., Ltd. RRQS40SX. The layer thickness of the glass plate is generally in the range of 200 μm to 10 mm.

  Further, a fluororesin coating layer may be provided on the surface of the glass plate (on the surface on which the phosphor layer is not provided) in order to enhance the stain resistance of the glass plate. The fluororesin coating layer can be formed by coating a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent on the surface of the glass plate and drying. Although the fluororesin may be used alone, it is usually used as a mixture of a fluororesin and a resin having a high film forming property.

  In addition, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used in combination. The fluororesin coating layer can be filled with a fine particle filler in order to reduce interference unevenness and further improve the image quality of the radiation image. The thickness of the fluororesin coating layer is usually in the range of 0.5 to 20 μm. In forming the fluororesin coating layer, additive components such as a cross-linking agent, a hardener, and a yellowing inhibitor can be used. In particular, the addition of a crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

  A phosphor layer is provided on one surface of the glass plate using a vapor deposition method. A dichroic coat, an antireflection coat, or a microlens that transmits only light of a specific wavelength may be provided on the surface of the glass plate.

  The stimulable phosphor is preferably a stimulable phosphor that exhibits stimulated emission in a wavelength range of 300 to 500 nm when irradiated with excitation light having a wavelength of 400 to 900 nm.

Among these, basic composition formula (I):
M ^I X · aM ^II X ' ₂ · bM ^III X " ₃ : zA (I)
An alkali metal halide photostimulable phosphor represented by the formula (1) is particularly preferred. M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and M ^II consists of Be, Mg, Ca, Sr, Ba, Ni, Cu, Zn, and Cd. at least one rare earth element or trivalent metal selected from the group, M ^III is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Represents at least one rare earth element or trivalent metal selected from the group consisting of Yb, Lu, Al, Ga and In, and A represents Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho Represents at least one rare earth element or metal selected from the group consisting of Er, Tm, Yb, Lu, Na, Mg, Cu, Ag, Tl and Bi. X, X ′ and X ″ each represent at least one halogen selected from the group consisting of F, Cl, Br and I. a, b and z are 0 ≦ a <0.5 and 0 ≦ b <, respectively. It represents a numerical value within the range of 0.5 and 0 <z <1.0.

M ^I in the basic composition formula (I) preferably contains at least Cs. X preferably contains at least Br. A is particularly preferably Eu or Bi. In addition, in the basic composition formula (I), if necessary, a metal oxide such as aluminum oxide, silicon dioxide, zirconium oxide or the like is added in an amount of 0.5 mol or less with respect to 1 mol of M ^I. May be added.

The basic composition formula (II):
M ^II FX: zLn (II)
Also preferred are rare earth activated alkaline earth metal fluoride halide stimulable phosphors. M ^II represents at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca, and Ln represents Ce, Pr, Sm, Eu, Tb, Dy, Ho, Nd, Er, Tm and Yb. Represents at least one rare earth element selected from the group consisting of X represents at least one halogen selected from the group consisting of Cl, Br and I. z represents a numerical value within the range of 0 <z ≦ 0.2.

In M ^II in the basic composition formula (II), Ba preferably occupies half or more. Ln is particularly preferably Eu or Ce. Further, in the basic composition formula (II), it appears as F: X = 1: 1 on the notation, but this indicates that it has a BaFX-type crystal structure, and the stoichiometric value of the final composition. It does not indicate composition. In general, a state in which many F ⁺ (X ⁻ ) centers, which are X ⁻ ion vacancies, are generated in a BaFX crystal is preferable in order to increase the photostimulation efficiency with respect to light of 600 to 700 nm. At this time, F is often slightly more excessive than X.

Although omitted in the basic composition formula (II), one or more of the following additives may be added to the basic composition formula (II) as necessary.
bA, wN ^I , xN ^II , yN ^III
However, A represents a metal oxide such as Al ₂ O _3, SiO ₂ and ZrO _2. In preventing sintering between M ^II FX particles, it is preferable to use an average particle size of the primary particles has low reactivity with M ^II FX in the following ultrafine particles 0.1 [mu] m. N ^I represents at least one alkali metal compound selected from the group consisting of Li, Na, K, Rb and Cs, N ^II represents an alkaline earth metal compound composed of Mg and / or Be, N ^III represents a compound of at least one trivalent metal selected from the group consisting of Al, Ga, In, Tl, Sc, Y, La, Gd, and Lu. Although it is preferable to use a halide as these metal compounds, it is not limited thereto.

In addition, b, w, x, and y are the amounts added to the feed when the number of moles of M ^II FX is 1, and 0 ≦ b ≦ 0.5, 0 ≦ w ≦ 2, 0 ≦ x ≦ 0. 3 represents a numerical value within each range of 0 ≦ y ≦ 0.3. These numerical values do not represent the ratio of elements contained in the final composition with respect to the additive that is reduced by firing or subsequent cleaning treatment. Some of the compounds remain as added in the final composition, while others react with or be taken up by M ^II FX.

In addition, in the basic composition formula (II), if necessary, Zn and Cd compounds; metal oxides TiO ₂ , BeO, MgO, CaO, SrO, BaO, ZnO, Y ₂ O ₃ , La ₂ O ₃ In ₂ O ₃ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , ThO ₂ ; Zr and Sc compound; B compound; As and Si compound; tetrafluoroboric acid compound; hexafluorosilicic acid, hexa Hexafluoro compounds composed of monovalent or divalent salts of fluorotitanic acid and hexafluorozirconic acid; compounds of transition metals such as V, Cr, Mn, Fe, Co and Ni may be added. Furthermore, in the present invention, not only the phosphor containing the above-mentioned additives, but any material having a composition basically regarded as a rare earth activated alkaline earth metal fluoride halide stimulable phosphor. It may be.

However, in the present invention, the phosphor is not limited to the stimulable phosphor, and may be a phosphor that absorbs radiation such as X-rays and emits (instantaneous) emission in the ultraviolet to visible region. Examples of such phosphors include LnTaO ₄ : (Nb, Gd), Ln ₂ SiO ₅ : Ce, LnOX: Tm (Ln is a rare earth element), CsX (X is a halogen). Gd ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Pr, Ce, ZnWO ₄ , LuAlO ₃ : Ce, Gd ₃ Ga ₅ O ₁₂ : Cr, Ce, HfO _{2 and the} like.

  In the present invention, the phosphor layer can be formed on the glass plate as follows, for example, by vapor deposition which is a kind of vapor deposition method. According to this vapor deposition method, a phosphor layer made of columnar crystals of phosphor without containing a binder can be obtained. For this reason, it is possible to improve the entrance efficiency of the excitation light and the extraction efficiency of the emitted light, so that the sensitivity is high, and the scattering of the excitation light in the plane direction can be prevented, so that a high sharpness image can be obtained. It becomes. Further, in the electron beam evaporation method, a columnar crystal having a good shape and a well-aligned arrangement can be obtained.

First, a rigid sheet mainly composed of a storage phosphor that is an evaporation source and an organic resin material that is an evaporation target is installed in the vapor deposition apparatus, and the inside of the apparatus is evacuated to 1 × 10 ⁻⁵ to 1 ×. The degree of vacuum is about 10 ⁻² Pa. At this time, an inert gas such as Ar gas or Ne gas may be introduced while maintaining the degree of vacuum at this level. The stimulable phosphor is preferably processed into a tablet (tablet) shape by pressure compression. Heating may be performed during compression, and after compression, the obtained tablet may be subjected to dehydration and degassing treatment by heating under reduced pressure. Moreover, it is also possible to use the raw material or raw material mixture instead of the phosphor.

  An electron beam is generated from an electron gun with an acceleration voltage of 1.5 kV or more and 5.0 kV or less, and irradiated to the evaporation source. Thereby, the stimulable phosphor is heated to evaporate and scatter, and is deposited on the surface of the glass plate material. The deposition rate is generally in the range of 0.1 to 1000 μm / min, preferably in the range of 1 to 100 μm / min. Note that two or more phosphor layers may be formed by performing electron beam irradiation in a plurality of times, or different phosphors may be co-evaporated using a plurality of electron guns. It is also possible to form a phosphor layer at the same time as the phosphor is synthesized on a glass plate using the phosphor material. Furthermore, the vapor deposition target (glass plate) may be cooled or heated as necessary during vapor deposition, or the phosphor layer may be heat treated (annealed) after vapor deposition.

  In this way, a layer is obtained in which columnar crystals made of a stimulable phosphor are grown in the thickness direction on a glass plate. The layer thickness of the phosphor layer is usually in the range of 50 to 1000 μm, preferably in the range of 200 μm to 700 mm. This phosphor layer does not contain a binder and consists only of the phosphor, and there are voids (cracks) between the columnar crystals of the phosphor.

  Note that the vapor deposition method is not limited to the above-described electron beam evaporation method, and other known methods such as a resistance heating method and the like, a sputtering method, and a chemical vapor deposition (CVD) method should be used. Can do. These methods may be used in combination with a vapor deposition method.

  Alternatively, the stimulable phosphor layer is formed by applying a coating solution in which the particles of the stimulable phosphor and the binder are dispersed and dissolved in an appropriate organic solvent on a glass plate using a coating machine, and drying the coating solution. It is good also as a fluorescent substance layer which consists of fluorescent substance particles and the binder which disperse-supports it. The ratio of the binder to the phosphor in the coating solution is usually in the range of 1: 1 to 1: 100 (weight ratio), and preferably in the range of 1: 8 to 1:40 (weight ratio). The binder can be appropriately selected from known various binder resins.

  In addition, it is not always necessary to form the stimulable phosphor layer directly on the glass plate. After forming the phosphor layer on a separately prepared substrate (temporary support), the phosphor layer is peeled off from the substrate, and the glass plate You may adhere | attach using an adhesive agent etc. on the top.

  On this phosphor layer, if desired, a light reflecting material such as alumina, titanium dioxide, barium sulfate or the like is used as a main component in order to improve sensitivity or image quality (sharpness, graininess) as a radiation image converter. A light reflecting layer or a light absorbing layer made of a light absorbing material such as carbon black or ultramarine may be provided.

  Further, as described above, a filling resin layer is provided on the phosphor layer in order to improve the parallel flatness of the radiation image converter. The filled resin layer is desirably lower in density and softer than a rigid sheet mainly composed of an organic resin material, and has less radiation absorption. Examples of the filling resin used in such a filling resin layer include nonwoven fabrics, synthetic fibers and natural fibers, or woven fabrics and glass fibers thereof; fine urethane foam, polyethylene terephthalate foam, porous ceramics, microfilters, and the like. Those having pores (voids); general resins, especially resins having a density of 1.7 or less, such as silicone, polyurethane, acrylic resin, epoxy resin; and hollow particles (hollow polymers, etc.) mixed with a binder Can be mentioned. Further, as described above, the filling resin layer may be formed of a vibration absorbing material.

  As binders for dispersing the hollow particles, polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, ethylene vinyl acetate, polyvinyl chloride, natural rubber, fluoro rubber, polyisoprene, chlorinated polyethylene, styrene-butadiene rubber, silicon rubber And the like.

  When the filling resin has adhesiveness, a filling resin layer is formed on the phosphor by coating or the like, and then a rigid sheet mainly composed of an organic resin material is joined with the filling resin. When the filling resin does not have adhesiveness, the filling resin is bonded onto the phosphor layer with an adhesive, and then a rigid sheet mainly composed of an organic resin material is bonded onto the filling resin layer with an adhesive. . The layer thickness of the filled resin layer is generally in the range of 100 μm to 10 mm, and preferably in the range of 1 to 5 mm.

  As the adhesive, those having excellent airtightness and low moisture permeability are preferable. For example, epoxy resin, phenol resin, cyanoacrylate resin, vinyl acetate resin, vinyl chloride resin, polyurethane resin, acrylic resin, Mention may be made of organic polymer adhesives such as ethylene vinyl acetate resins, polyolefin resins, chloroprene rubbers and nitrile rubbers; and silicone adhesives.

The rigid sheet mainly composed of an organic resin material preferably has an elastic modulus of 9.8 × 10 ³ MPa or more, more preferably 1.96 × 10 ^{4 to} 9.8 × 10 ⁶ MPa. Is in range. In addition, it is desirable that the rigid sheet containing the organic resin material as a main constituent material has little radiation absorption, and the X-ray absorption rate is generally 20% or less, preferably 10% or less. Furthermore, from the viewpoint of moisture resistance, it is desirable that the air tightness is excellent and the moisture permeability is low. The material of the rigid sheet mainly composed of such an organic resin material includes a carbon fiber reinforced plastic (CFRP) sheet, a plastic sheet such as a glass fiber reinforced plastic (GFRP), and a porous ceramic. Mention may be made of ceramic sheets. The layer thickness of the rigid sheet mainly composed of an organic resin material is generally in the range of 100 μm to 10 mm, and preferably in the range of 1 to 5 mm. When the glass plate has rigidity, it is not always necessary to provide a rigid sheet whose main constituent material is an organic resin material.

  In order to increase the moisture resistance of the radiation image converter, a stimulable phosphor layer (and a filling resin layer, etc.) may be formed on the inner side of the glass plate and a frame spacer may be provided therearound. As the frame spacer, those having excellent airtightness and low moisture permeability are preferable, and specific examples thereof include sealing agents such as the above-described adhesive and low-melting glass. Alternatively, a frame body (spacer) made of glass, ceramics, metal, plastic, or the like is used between the glass plate and a rigid sheet mainly composed of an organic resin material by using the above adhesive or adhesive filling resin. You may join. The frame is preferably integrated.

  A vibration-absorbing material, which is a characteristic feature of the present invention, is provided on a rigid sheet (or a storage phosphor layer, a filling resin layer, or the like) whose main constituent material is an organic resin material. The vibration-absorbing material may be directly layered on the rigid sheet, or may be adhered on the rigid sheet using an adhesive.

  The film thickness of the metal thin film that may be used in combination with the vibration absorbing material is usually in the range of 0.1 to 700 μm. In the case of a metal film (metal foil), it is preferably in the range of 10 to 350 μm, and in the case of a deposited thin film, it is preferably in the range of 0.1 to 10 μm.

  In order to further improve the vibration resistance and impact resistance of the radiation image converter, the vibration-absorbing material is applied not only to the outer surface of the rigid sheet mainly composed of an organic resin material, but also to the peripheral side surface of the radiation image converter. May also be provided. Further, the vibration-absorbing material may extend to the outer surface edge of the glass plate. In this case, the vibration-absorbing material is preferably provided integrally.

  Alternatively, in order to protect the stimulable phosphor layer from vibrations and shocks, as shown in FIG. 4, the vibration-absorbing material is a phosphor layer side surface of a rigid sheet mainly composed of an organic resin material, Or you may provide in the surface on the opposite side to the glass plate of a fluorescent substance layer.

  Although the radiation image converter of the present invention is obtained as described above, the configuration of the radiation image converter of the present invention may include various known variations. For example, for the purpose of improving the sharpness of the obtained image, any one of the above layers may be colored with a colorant that absorbs excitation light and does not absorb emitted light.

It is a schematic sectional drawing which shows an example of a structure of the radiographic image converter of this invention. It is a schematic sectional drawing which shows another structural example of the radiographic image converter of this invention. It is a schematic sectional drawing which shows another structural example of the radiographic image converter of this invention. It is a schematic sectional drawing which shows another structural example of the radiographic image converter of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass plate 12 Phosphor layer 13 Filling resin layer 14 Rigid sheet 15 having organic resin material as main constituent material Frame spacers 16a to 16d Vibration absorbing material

Claims (7)

  A non-moisture permeable rigid sheet having a phosphor layer formed on one surface by a vapor deposition method and another non-moisture permeable rigid sheet are in a state of facing each other with the phosphor layer facing inward, and the side surface is impermeable to moisture. In the radiation image converter in which at least one of the non-breathable rigid sheets is transparent, a vibration-absorbing material is provided on at least one surface of at least one of the plurality of non-breathable rigid sheets. A radiation image converter characterized by being attached.   The radiation image converter according to claim 1, wherein the non-moisture permeable rigid sheet having a phosphor layer formed on the surface thereof is transparent, and the vibration absorbing material is attached to the surface of another non-moisture permeable rigid sheet. .   The radiation image converter according to claim 2, wherein the non-moisture permeable rigid sheet to which the vibration absorbing material is attached is a carbon fiber reinforced resin molded body sheet.   The radiation image converter according to claim 2 or 3, wherein the vibration-absorbing material is attached to the outer surface of another moisture-impermeable rigid sheet.   The radiation image converter according to claim 2 or 3, wherein the vibration-absorbing material is attached to the inner surface of another non-breathable rigid sheet.   The radiation image converter according to claim 1, wherein the vibration-absorbing material is attached to the outer surface of the non-moisture permeable rigid sheet having a phosphor layer formed on the surface, and the other non-moisture permeable rigid sheet is transparent. . The radiation image converter according to claim 6, wherein the vibration-absorbing material is attached to the outside of another non-breathable rigid sheet.

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