JP2003329798A - Radiation image conversion panel and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel which has less afterglow, high intensity and high sharpness and a method for manufacturing the radiation image conversion panel. <P>SOLUTION: The radiation image conversion panel which has stimulable phosphor layers on a support is characterized in that at least one of the stimulable phosphor layers is formed by a vapor phase method (or a vapor phase deposition method) so that its film thickness will be 50 μm to 1 mm and two or more rare-earth compounds are contained in the phosphor composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a radiation image conversion panel and a method for manufacturing a radiation image conversion panel.

[0002]

2. Description of the Related Art Conventionally, a so-called radiographic method using a silver salt for obtaining a radiographic image has been used, but a method for forming a radiographic image without using the silver salt has been developed. That is, the radiation that has passed through the subject is absorbed by the fluorescent substance, and then this fluorescent substance is excited with a certain energy to cause the radiation energy accumulated by this fluorescent substance to be emitted as fluorescent light, and this fluorescent light is detected. A method of imaging is disclosed.

As a concrete method, there is known a radiation image conversion method using a panel having a stimulable phosphor layer provided on a support and using one or both of visible light and infrared as excitation energy ( U.S. Pat. No. 3,859,52
(See No. 7).

A radiation image conversion method using a stimulable phosphor having higher brightness and higher sensitivity is disclosed in, for example, JP-A-59-75.
BaFX: Eu ²⁺ system (X:
Cl, Br, I) Radiation image conversion method using phosphor
A radiographic image conversion method using an alkali halide phosphor as described in JP-A-61-72087,
-73786, 61-73787, etc., Tl ⁺ and Ce ³⁺ , Sm ³⁺ , E as co-activators.
Alkali halide phosphors containing metals such as u ³⁺ , Y ³⁺ , Ag ⁺ , Mg ²⁺ , Pb ²⁺ and In ³⁺ have been developed.

Further, in recent years, a radiation image conversion panel having higher sharpness has been demanded in analysis of diagnostic images. As a means for improving the sharpness, for example, attempts have been made to improve the sensitivity and the sharpness by controlling the shape itself of the stimulable phosphor formed.

As one of the methods of these attempts, for example, a fine pseudo columnar structure formed by depositing a stimulable phosphor on a support having a fine concavo-convex pattern as described in JP-A-61-242497. There is a method of using a stimulable phosphor layer composed of blocks.

Further, as described in JP-A-61-142500, a crack between columnar blocks obtained by depositing a stimulable phosphor on a support having a fine pattern is shock-treated to further A method of using a radiation image conversion panel having a developed photostimulable phosphor layer, and further, a photostimulable phosphor layer formed on a support described in JP-A-62-39737, the surface of which. A method of using a radiation image conversion panel in which cracks are generated from the side to form a pseudo column, and further, as described in JP-A-62-110200, a stimulable material having cavities on a support by vapor deposition. A method has also been proposed in which, after forming the phosphor layer, a cavity is grown by heat treatment to form a crack.

Further, in JP-A-2-58000, elongated columnar crystals having a constant inclination with respect to the normal direction of the support are formed on the support by a vapor phase growth method (vapor deposition method). A radiation image conversion panel having a stimulable phosphor layer is described.

In any of these methods for controlling the shape of the stimulable phosphor layer, the stimulable phosphor layer is formed into a columnar shape to suppress lateral diffusion of stimulated excitation light or stimulated emission. Since it can reach the surface of the support while repeating reflection at the crack (columnar crystal) interface, the sharpness of the image due to stimulated emission can be remarkably increased.

Recently, there has been proposed a radiation image conversion panel using a stimulable phosphor in which Eu is activated with an alkali halide such as CsBr as a matrix, and it has been impossible by using Eu as an activator. It has become possible to improve the line conversion efficiency.

However, in the host crystal of alkali halide, when the composition with increased X-ray absorption is increased, the strain of the phosphor crystal becomes large, and since it has a large number of emission levels, it has a high luminance, but at the emission wavelength. The light emission distribution is broad and the light emission is broad. This broad emission has a remarkable effect when Eu is used as the activator, and although the luminance is high, the afterglow and the response are deteriorated because the distribution in the emission level is widened.

When an alkali halide is used for a CR detector as a radiation imaging system, the problem of this afterglow characteristic is large, and in particular, in a radiation imaging system, the effect of instantaneous afterglow causes a fixed time until reading after X-ray exposure. It is necessary to read after placing, and the effect of photostimulable afterglow is that deterioration of reading contrast due to afterglow poses a problem and adversely affects the reading speed (reading cycle, number of times of use). I found out.

Therefore, there is still a demand from the market for further improvement of the brightness and sharpness of the radiation image conversion panel, and improvement of the afterglow characteristics (instantaneous afterglow, stimulated afterglow) commensurate with the speeding up.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation image conversion panel and a radiation image conversion panel which exhibit excellent contrast due to less afterglow (instantaneous afterglow, photostimulable afterglow), high brightness and high sharpness. It is to provide a method for manufacturing an image conversion panel.

[0015]

The above object of the present invention can be achieved by the following constitutions.

1. In a radiation image conversion panel having a stimulable phosphor layer on a support, at least one stimulable phosphor layer is formed by a gas phase method (also referred to as a vapor phase deposition method).
A radiation image conversion panel, which is formed to have a film thickness of μm to 1 mm and which contains two or more kinds of rare earth compounds uniformly in the phosphor composition.

2. The at least one stimulable phosphor layer contains a stimulable phosphor having an alkali halide represented by the general formula (1) as a matrix, and the stimulable phosphor layer is vapor-phase grown. Method (also called vapor deposition method) 50 μm to 1
2. The radiation image conversion panel as described in 1 above, which is formed to have a film thickness of mm.

3. 3. The radiation image conversion panel according to 1 or 2, wherein at least one rare earth compound among the two or more rare earth compounds in the phosphor composition has a Cs atom.

4. The radiation image conversion panel according to any one of the above 1 to 3, wherein the amount of photostimulable afterglow after 300 msec of X-ray bombardment is 0.0001 to 0.1%.

5. The radiation image conversion panel as described in 4 above, wherein the instantaneous light emission afterglow amount after 300 msec of X-ray bombardment is 0.0001 to 0.01%.

6. A method for manufacturing a radiation image conversion panel, comprising manufacturing the radiation image conversion panel according to any one of 1 to 5 in an atmosphere of dry air.

The present invention will be described in more detail below. In the radiation image conversion panel of the present invention, at least one stimulable phosphor layer on the support is a vapor phase method (also referred to as a vapor phase deposition method).
Is formed to have a film thickness of 50 μm to 1 mm, and the phosphor composition contains two or more kinds of rare earth compounds uniformly.

Here, the term “uniformly contained” means that the amount of activator present in the phosphor layer is the same as that of the activator in the phosphor surface.

Specifically, it means that the amount of the activator present on the support side of the phosphor layer and the amount of the activator present on the surface side are within ± 10%,
As a confirmation method, the amount of activator present in the phosphor layer is about 10 on the surface side of the phosphor layer formed as a phosphor layer of about 500 μm.
100μ between the sample and the phosphor layer on the support side
Each of the samples of m is dissolved in pure water to obtain an aqueous solution. This aqueous solution can be analyzed by ICP to calculate and confirm the amount of activator.

In the present invention, having two or more kinds of rare earth compounds in the phosphor composition means that, for example, when there are three kinds of rare earth compounds, there are three kinds of phosphor activators, and each of the phosphor activators is a phosphor. The main activator, phosphor sub-activator 1 and phosphor sub-activator 2 are used.

Phosphor main activator (hereinafter also referred to as main activator), phosphor sub activator 1 (hereinafter also referred to as sub activator 1)
The phosphor sub-activator 2 (hereinafter, also referred to as the sub-activator 2) will be described.

1) Phosphor Subactivator 1 When the subactivator 1Gd is added as a diffusion inhibitor for the main activator Eu, the thermal diffusion rate of the main activator Eu is suppressed by the presence of Gd, and the main activator after the vapor deposition film is formed. It is possible to prevent the agent Eu from being unevenly distributed in the phosphor crystal and from being separated from the vapor deposition film, so that the emission distribution can be stabilized.

The amount of Eu used is usually 5 × 10 ^-4 g, but it may be used in the range of 5 × 10 ^{-2 to} 5 × 10 ^-5 g.

The amount of Gd used is usually 5 × 10 ^-5 g, but it may be used in the range of 5 × 10 ^{-2 to} 5 × 10 ^-5 g.

2) Phosphor subactivator 2 When the subactivator 2Ce is added as a level stabilizer of the main activator Eu, the presence of Ce causes the main activator Eu to the phosphor crystal.
The stability of the phosphor crystal increases due to the lattice defects introduced,
Even if the main activator Eu is ubiquitous, the luminescence distribution does not spread,
The luminescence becomes sharp.

3) Vapor deposition method In forming a vapor deposition film by vapor phase deposition, phosphor host crystal Cs
Impurities (activator) added to Br lower the melting point of the phosphor material.

Particularly, the main activator Eu is added to the phosphor host crystal CsB.
When the phosphor raw material (CsBr: Eu) added to r has a low melting point and is vapor-deposited by heating, it gradually volatilizes from CsBr having a low melting point (melting point of about 645 ° C.) in the vapor deposition film formation stage, and serves as a main activator. The amount of Eu to be introduced into
In addition, Eu is present in the crystal lattice (lattice defect) of the CsBr crystal, the obtained columnar crystal is in a deformed crystalline state, light scattering occurs in the columnar crystal, and sharpness for laser excitation is obtained. Cause decrease.

Therefore, when the main activator Eu is introduced in CsBr vapor deposition, for example, CsBr and EuBr are introduced.
_When using a phosphor material that is a mixture of ₂ and vapor deposition,
The phosphor material is heated at a temperature higher than the melting point of EuBr ₂ (705 ° C.) by 20 ° C. or more to form a vapor deposition film.

(Csa, Eub) Brx (a + b = x)
When vapor-depositing a double salt crystal as a raw material is vapor-deposited, the raw material is heated at a temperature higher than the melting point of EuBr ₂ by 20 ° C. or more to form vapor. Therefore, it is preferable that the film thickness formation rate during evaporation is 20 μm / min or more, and 60 μm or more.
Most preferably m / min or more.

However, since the amount of vapor generated cannot be sufficiently controlled only by controlling the heating based on the melting point, the crystals obtained on the substrate do not show fine needle-like crystals having a columnar shape, and it can be said that the effect of the sharpness of the phosphor is sufficient. Absent.

Therefore, according to the present invention, the sub-activators Ce and Gd are added to suppress the melting point of the phosphor raw material within a certain range and the deposition amount of the phosphor raw material on the substrate is kept constant between the vapor deposition source and the substrate. It is preferable to form a plate to limit the amount of volatilization.

The baffle installed between the substrate and the source of vapor deposition of the raw material is parallel to the raw material and the substrate, and has a shape in which the passage is greatly suppressed in the center and less in the side according to the volatilization temperature (eg, the number of holes: It is more preferable to form so as to have a small number in the center and a large number of sides.

Further, the full width at half maximum of the emission wavelength of the phosphor becomes one of the factors showing the state of the crystal, and when the half width is wide, the crystal collapses.
It is preferable because it does not cause light scattering in the columnar crystals and is sharp.

The emission wavelength of the phosphor is measured by a usual absorption spectrum device. The radiation image conversion panel of the present invention has a photostimulable afterglow ratio of 0.0001 to 300 msec after X-ray irradiation.
0.1% is preferable, X-ray exposure is 300 mse
The instantaneous light emission afterglow ratio after c is preferably 0.0001 to 0.01%, and in this range, a radiation image conversion panel having good contrast can be obtained.

Next, the stimulable phosphor represented by the general formula (1), which is preferably used in the present invention, will be described.

In the stimulable phosphor represented by the general formula (1), M ^I represents at least one alkali metal atom selected from each atom such as Na, K, Rb and Cs, and among them, Rb And at least one kind of alkaline earth metal atom selected from each atom of Cs, and more preferably Cs atom.

M ² is Be, Mg, Ca, Sr, Ba, Z
It represents at least one divalent metal atom selected from each atom such as n, Cd, Cu and Ni, and among them, preferably used is selected from each atom such as Be, Mg, Ca, Sr and Ba. It is a divalent metal atom.

M ³ is Sc, Y, La, Ce, Pr, N
d, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
It represents at least one trivalent metal atom selected from each atom such as r, Tm, Yb, Lu, Al, Ga and In, among which Y, Ce, Sm and E are preferably used.
It is a trivalent metal atom selected from each atom such as u, Al, La, Gd, Lu, Ga and In.

A is Eu, Tb, In, Ce, Tm, D
y, Pr, Ho, Nd, Yb, Er, Gd, Lu, S
It is at least two kinds of metal atoms selected from each atom of m, Y, Tl, Na, Ag, Cu and Mg.

From the viewpoint of improving the stimulated emission brightness of the stimulable phosphor, X, X'and X "represent at least one halogen atom selected from each atom of F, Cl, Br and I.
At least one halogen atom selected from F, Cl and Br is preferable, and at least one halogen atom selected from Br and I is more preferable.

In the general formula (1), the b value is 0 ≦.
It represents b <0.5, preferably 0 ≦ b ≦ 10 ⁻² .

The stimulable phosphor represented by the general formula (1) of the present invention is produced, for example, by the production method described below.

As the phosphor material, (a) NaF, Na
Cl, NaBr, NaI, KF, KCl, KBr, K
I, RbF, RbCl, RbBr, RbI, CsF, C
at least 1 selected from sCl, CsBr, and CsI
One kind or two or more kinds of compounds are used.

(B) MgF ₂ , MgCl ₂ , MgBr ₂ ,
MgI ₂ , CaF ₂ , CaCl ₂ , CaBr ₂ , CaI ₂ ,
SrF ₂ , SrCI ₂ , SrBr ₂ , SrI ₂ , BaF ₂ ,
BaCl ₂ , BaBr ₂ , BaBr ₂ .2H ₂ O, Ba
I ₂ , ZnF ₂ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , Cd
F ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ , Cu
Cl ₂ , CuBr ₂ , CuI, NiF ₂ , NiCl ₂ , Ni
At least one compound or two or more compounds selected from compounds of Br ₂ and NiI ₂ are used.

(C) In the general formula (1), Eu,
Tb, In, Cs, Ce, Tm, Dy, Pr, Ho, N
d, Yb, Er, Gd, Lu, Sm, Y, Tl, Na,
A compound having a metal atom selected from each atom such as Ag, Cu and Mg is used.

In the compound represented by the general formula (1),
a is 0 ≦ a <0.5, preferably 0 ≦ a <0.01, b
Is 0 ≦ b <0.5, preferably 0 ≦ b ≦ 10 ⁻² , and e is 0
<E ≦ 0.2, preferably 0 <e ≦ 0.1.

The phosphor raw materials (a) to (c) described above are weighed so as to obtain a mixed composition within the above numerical range, and sufficiently mixed using a mortar, a ball mill, a mixer mill or the like.

After firing once under the above firing conditions, the fired product is taken out of the electric furnace and crushed, and then the fired product powder is charged again in a heat-resistant container and placed in the electric furnace to perform the same firing as described above. The light emission brightness of the phosphor can be further increased by performing the re-baking under the conditions. Further, when the baked product is cooled to the room temperature from the baking temperature, the baked product is taken out of the electric furnace and allowed to cool in the air. Although a desired phosphor can be obtained, the phosphor may be cooled in the same weak reducing atmosphere or neutral atmosphere as when firing. Further, by moving the fired product from the heating unit to the cooling unit in the electric furnace and quenching it in a weak reducing atmosphere, a neutral atmosphere or a weak oxidizing atmosphere,
The emission brightness due to the stimulation of the obtained phosphor can be further increased.

The photostimulable phosphor layer of the present invention is formed by the vapor phase growth method. As the vapor phase growth method of the stimulable phosphor, a vapor deposition method, a sputtering method, a CVD method, an ion plating method, or the like can be used.

In the present invention, for example, the following methods can be mentioned. The vapor deposition method of the first method is as follows. First, the support is installed in the vapor deposition apparatus, and then the apparatus is evacuated to 1.333 ×.
The degree of vacuum is set to about 10 ⁻⁴ Pa.

Next, at least one of the stimulable phosphors is heated and evaporated by a method such as a resistance heating method or an electron beam method to grow the stimulable phosphor on the surface of the support to a desired thickness.

As a result, the stimulable phosphor layer containing no binder is formed, but it is also possible to form the stimulable phosphor layer in a plurality of times in the vapor deposition step.

In the vapor deposition step, a plurality of resistance heaters or electron beams are used for co-evaporation to synthesize the desired stimulable phosphor on the support and simultaneously form a stimulable phosphor layer. Is also possible.

After completion of the vapor deposition, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side of the stimulable phosphor layer opposite to the support side, if necessary. Incidentally, after forming the stimulable phosphor layer on the protective layer, a procedure of providing a support may be adopted.

Further, in the vapor deposition method, during vapor deposition,
The material to be vapor-deposited (support, protective layer or intermediate layer) may be cooled or heated as necessary.

After the completion of vapor deposition, the stimulable phosphor layer may be heat-treated. Further, in the above vapor deposition method, reactive vapor deposition in which a gas such as O ₂ or H ₂ is introduced and vapor deposition may be performed, if necessary.

The sputtering method as the second method is
Similar to the vapor deposition method, a support having a protective layer or an intermediate layer is placed in a sputtering apparatus, and then the apparatus is evacuated to a vacuum degree of about 1.333 × 10 ⁻⁴ Pa and then used as a gas for sputtering. 1.333 × 10 ^-1 P by introducing an inert gas such as Ar or Ne into the sputtering apparatus
The gas pressure is about a. Next, by using the stimulable phosphor as a target, sputtering is performed to grow a stimulable phosphor layer on the support to a desired thickness.

In the sputtering process, various applied treatments can be used as in the vapor deposition method.

The third method is the CVD method, and the fourth method is the ion plating method.

The growth rate of the stimulable phosphor layer in the vapor phase growth is preferably 0.05 μm / min to 300 μm / min. When the growth rate is less than 0.05 μm / min, the productivity of the radiation image conversion panel of the present invention is poor, which is not preferable. When the growth rate exceeds 300 μm / min, it is difficult to control the growth rate, which is not preferable.

When the radiation image conversion panel is obtained by the above-mentioned vacuum deposition method, sputtering method, etc., since the binder is not present, the packing density of the stimulable phosphor can be increased, and the sensitivity and resolution can be improved. Is preferable because a preferable radiation image conversion panel can be obtained.

The film thickness of the stimulable phosphor layer varies depending on the purpose of use of the radiation image conversion panel and the type of the stimulable phosphor, but is 50 μ from the viewpoint of obtaining the effect of the present invention.
m to 1 mm, preferably 50 to 300 μm, more preferably 100 to 300 μm, and particularly preferably 150 to 300 μm.

In the production of the stimulable phosphor layer by the above vapor phase growth method, the temperature of the support on which the stimulable phosphor layer is formed is preferably set to 100 ° C. or higher, more preferably 150 ° C or higher, particularly preferably 150
~ 400 ° C.

From the viewpoint of obtaining a radiation image conversion panel exhibiting high sharpness, the reflectance of the stimulable phosphor layer of the present invention is 20% or more, preferably 30% or more, more preferably It is 40% or more. The upper limit is 100%.

A filler such as a binder may be filled in the gaps between the columnar crystals to reinforce the stimulable phosphor layer, and a substance having a high light absorption and a substance having a high light reflectance are filled. Maybe,
This is effective not only for providing a reinforcing effect but also for reducing the lateral light diffusion of the photostimulated excitation light that has entered the photostimulable phosphor layer.

Next, the formation of the stimulable phosphor layer of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing an example of a stimulable phosphor layer having columnar crystals formed on a support by using the vapor phase growth method described above. Reference numeral 11 is a support, 12 is a stimulable phosphor layer, and 13 is a columnar crystal constituting the stimulable phosphor layer. Incidentally, 14 indicates a gap formed between the columnar crystals.

FIG. 2 is a view showing a state in which a stimulable phosphor layer is formed on a support by vapor deposition, and the stimulable phosphor vapor stream 16 with respect to the normal direction (R) to the support surface is shown. If the incident angle is θ ₂ (incident at 60 ° in the figure), the angle of the formed columnar crystal with respect to the normal direction (R) of the support surface is θ ₁ (about 30 ° in the figure, empirically Columnar crystals are formed at this angle.

Since the stimulable phosphor layer thus formed on the support does not contain a binder, it has excellent directivity, and the directivity of stimulated excitation light and stimulated emission is excellent. The layer thickness is higher than that of a radiation image conversion panel having a dispersion-type stimulable phosphor layer in which a stimulable phosphor is dispersed in a binder. Further, the scattering of the stimulable excitation light in the stimulable phosphor layer is reduced to improve the sharpness of the image.

A filler such as a binder may be filled in the gap between the columnar crystals to reinforce the stimulable phosphor layer, and a substance having a high light absorption and a substance having a high light reflectance may be filled. May
This is effective not only for providing the above-mentioned reinforcing effect but also for reducing the lateral light diffusion of the photostimulable excitation light incident on the photostimulable phosphor layer.

A substance having a high reflectance means a stimulated excitation light (500
Up to 900 nm, especially 600 to 800 nm), and a white pigment and a coloring material in the green to red region such as aluminum, magnesium, silver, indium, and other metals can be used. White pigments can also reflect stimulated emission.

Examples of white pigments include TiO ₂ (anatase type, rutile type), MgO, PbCO ₃ .Pb
(OH) ₂ , BaSO ₄ , Al ₂ O ₃ , M (II) FX (provided that M (II) is at least one atom selected from each atom of Ba, Sr and Ca, and X is a Cl atom or B
r atom. ), CaCO ₃ , ZnO, Sb ₂ O ₃ , S
Examples thereof include iO ₂ , ZrO ₂ , lithopone (BaSO ₄ .ZnS), magnesium silicate, basic silicate sulfate, basic lead phosphate, and aluminum silicate.

Since these white pigments have a strong hiding power and a large refractive index, the photostimulable luminescence is easily scattered by reflecting or refracting light, and the sensitivity of the obtained radiation image conversion panel is remarkably improved. Can be made.

As the substance having a high light absorptivity, for example, carbon black, chromium oxide, nickel oxide, iron oxide and the like, and a blue coloring material are used. Of these, carbon black also absorbs stimulated emission.

The coloring material may be either organic or inorganic coloring material. Examples of organic colorants include Pomelo First Blue 3G (made by Hoechst), Estrol Brill Blue N-3RL (made by Sumitomo Chemical), and D & C Blue No.
1 (made by National Aniline), Spirit Blue (made by Hodogaya Chemical Co., Ltd.), Oil Blue No. 603 (manufactured by Orient), Kiton Blue A (manufactured by Ciba Geigy), Aizenka Tiron Blue GLH (manufactured by Hodogaya Chemical), Lake Blue AFH (manufactured by Kyowa Sangyo), Primocyanin 6GX (manufactured by Inabata Sangyo), Brill Acid Green 6BH (Hodogaya). Chemically manufactured), cyan blue BNRCS (manufactured by Toyo Ink), lionoyl blue SL (manufactured by Toyo Ink) and the like are used.

The color index No. 2441
1, 23160, 74180, 74200, 2280
0, 23154, 23155, 24401, 1483
0, 15050, 15760, 15707, 1794
1, 74220, 13425, 13361, 1342
0, 11836, 74140, 74380, 7435
Organic metal complex salt colorants such as 0 and 74460 are also included.

As the inorganic coloring material, ultramarine blue, for example, cobalt blue, cerulean blue, chromium oxide, TiO ₂ −
Inorganic pigments such as ZnO-Co-NiO type can be used.

As the support used in the radiation image conversion panel of the present invention, various kinds of glass such as polymer material,
Metals or the like are used, for example, quartz, borosilicate glass, plate glass such as chemically strengthened glass, or cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film,
A plastic film such as a polyimide film, a triacetate film or a polycarbonate film, a metal sheet such as an aluminum sheet, an iron sheet, a copper sheet or a metal sheet having a coating layer of the metal oxide is preferable.

That is, the surface of these supports may be a smooth surface, or the surface of the supports may be a matte surface for the purpose of improving the adhesiveness to the stimulable phosphor layer.

In the present invention, in order to improve the adhesiveness between the support and the stimulable phosphor layer, an adhesive layer may be provided in advance on the surface of the support, if necessary.

The thickness of these supports varies depending on the material of the support used and the like, but is generally 80 to 2000 μm, and more preferably 80 to 2000 from the viewpoint of handling.
It is 1000 μm.

Further, the stimulable phosphor layer of the present invention may have a protective layer. The protective layer may be formed by directly coating the protective layer coating solution on the stimulable phosphor layer, or a separately formed protective layer may be adhered onto the stimulable phosphor layer. Alternatively, a means for forming a stimulable phosphor layer on a separately formed protective layer may be used.

As a material for the protective layer, cellulose acetate,
Nitrocellulose, polymethylmethacrylate, polyvinylbutyral, polyvinylformal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoride-ethylene chloride, tetrafluoroethylene-hexafluoride Usual protective layer materials such as propylene copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer and the like are used.
Alternatively, a transparent glass substrate can be used as the protective layer.

Further, this protective layer may be formed by laminating an inorganic substance such as SiC, SiO ₂ , SiN or Al ₂ O ₃ by a vapor deposition method, a sputtering method or the like.

The layer thickness of these protective layers is 0.1 to 2000.
μm is preferred. FIG. 3 is a schematic diagram showing an example of the configuration of the radiation image conversion panel of the present invention.

In FIG. 3, 21 is a radiation generator, 22
Is a subject, 23 is a radiation image conversion panel having a stimulable phosphor layer of visible light or infrared light containing a stimulable phosphor,
24 is a stimulated excitation light source for emitting the radiation latent image of the radiation image conversion panel 23 as stimulated emission, 25 is a photoelectric conversion device for detecting the stimulated emission emitted from the radiation image conversion panel 23, and 26 is photoelectric conversion An image reproducing device that reproduces the photoelectrically converted signal detected by the device 25 as an image, 27 is an image display device that displays the reproduced image, and 28 is a radiation image conversion panel that cuts off the reflected light from the stimulated excitation light source 24. It is a filter for transmitting only the light emitted from 23.

Although FIG. 3 shows an example in which a radiation transmission image of a subject is obtained, the radiation generator 21 is not particularly required when the subject 22 itself emits radiation.

Further, the photoelectric conversion device 25 and thereafter may be any device capable of reproducing the optical information from the radiation image conversion panel 23 as an image in some form, and is not limited to the above.

As shown in FIG. 3, when the subject 22 is placed between the radiation generator 21 and the radiation image conversion panel 23 and the radiation R is irradiated, the radiation R is transmitted according to the change in the radiation transmittance of each part of the subject 22. And the transmitted image RI
(That is, an image of the intensity of radiation) is the radiation image conversion panel 2
It is incident on 3.

This incident transmission image RI is absorbed by the stimulable phosphor layer of the radiation image conversion panel 23, and as a result, the number of electrons and / or the number of electrons and / or that is proportional to the amount of radiation absorbed in the stimulable phosphor layer. Holes are generated and accumulated at the trap level of the stimulable phosphor.

That is, a latent image is formed by accumulating the energy of the radiation transmission image. Next, this latent image is excited by light energy to become visible.

Further, the photostimulable excitation light source 24 for irradiating light in the visible or infrared region irradiates the stimulable phosphor layer to expel the electrons and / or holes accumulated at the trap level to accumulate the accumulated energy. Is emitted as stimulated emission.

The intensity of the emitted stimulated emission is proportional to the number of accumulated electrons and / or holes, that is, the intensity of the radiation energy absorbed in the stimulable phosphor layer of the radiation image conversion panel 23. The optical signal is converted into an electric signal by the photoelectric conversion device 25 such as a photomultiplier tube, reproduced by the image reproduction device 26 as an image, and displayed by the image display device 27.

It is more effective for the image reproducing device 26 to use not only an electric signal as an image signal but also a so-called image processing, image calculation, image storage and storage.

Further, it is necessary to separate the reflected light of the photostimulable excitation light and the photostimulated luminescence emitted from the photostimulable phosphor layer when excited by light energy, and The photoelectric converter that receives the emitted light is generally 600 nm
The photostimulable luminescence emitted from the stimulable phosphor layer preferably has a spectral distribution in the short wavelength region as much as possible, because the sensitivity to the light energy of the following short wavelengths is high.

The emission wavelength range of the stimulable phosphor of the present invention is 30.
0 to 500 nm, while the stimulated excitation wavelength range is 500 to
Since it is 900 nm, the above conditions are satisfied at the same time, but recently, the downsizing of diagnostic equipment has advanced, and the excitation wavelength used for the image reading of the radiation image conversion panel has a high output and a semiconductor laser which is easy to be made compact. Preferably, the wavelength of the laser beam is preferably 680 nm, and the stimulable phosphor incorporated in the radiation image conversion panel of the present invention exhibits extremely good sharpness when an excitation wavelength of 680 nm is used. It is a thing.

That is, each of the stimulable phosphors of the present invention is 5
Emission having a main peak at 00 nm or less is shown, the stimulated excitation light can be easily separated, and the spectral sensitivity of the photodetector is in good agreement, so that the light can be efficiently received, and as a result, the sensitivity of the image receiving system can be increased.

As the stimulated excitation light source 24, a light source containing the stimulated excitation wavelength of the stimulable phosphor used in the radiation image conversion panel 23 is used. In particular, when laser light is used, the optical system becomes simple, and the intensity of stimulated excitation light can be increased, so that the stimulated emission efficiency can be increased, and more preferable results can be obtained.

Examples of the laser include He-Ne laser, He-Cd laser, Ar ion laser, Kr ion laser, N ₂ laser, YAG laser and its second harmonic, ruby laser, semiconductor laser, various dye lasers. ,
There is a metal vapor laser such as a copper vapor laser. Usually He
A continuous wave laser such as a —Ne laser or an Ar ion laser is preferable, but a pulsed laser can also be used if the scanning time of one pixel on the panel is synchronized with the pulse.

Further, without using the filter 28, the method disclosed in JP-A-59-59
In the case of the method of separating by utilizing the delay of light emission as shown in No. 22046, it is preferable to use a pulse oscillation laser rather than modulation using a continuous oscillation laser.

Among the various laser light sources described above, the semiconductor laser is particularly preferable because it is small and inexpensive, and a modulator is unnecessary.

The filter 28 transmits the stimulated emission emitted from the radiation image conversion panel 23 and cuts the stimulated excitation light. Therefore, this is a stimulable phosphor contained in the radiation image conversion panel 23. Of the stimulated emission wavelength and the wavelength of the stimulated excitation light source 24.

For example, the stimulated excitation wavelength is 500 to 900 n.
In the case of a practically preferable combination such that the stimulated emission wavelength is 300 to 500 nm in m, the filter is, for example, C-39, C-40, V-40, V-42, V manufactured by Toshiba Corporation.
-44, Corning 7-54, 7-59, Spectrofilm BG-1, BG-3, BG-25, BG.
A purple to blue glass filter such as -37 or BG-38 can be used. Further, if an interference filter is used, a filter having arbitrary characteristics can be selected and used to some extent. The photoelectric conversion device 25 may be a photoelectric tube, a photomultiplier tube, a photodiode, a phototransistor, a solar cell, a photoconductive element, or any other device capable of converting a change in the amount of light into a change in an electronic signal.

[0108]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 << Preparation of Radiation Image Conversion Panel Samples 1 to 5 (Indicated as Samples 1 to 5 in Table 1) >> 1 mm thick crystallized glass (manufactured by Nippon Electric Glass Co., Ltd.) under the conditions shown in Table 1. ) A stimulable phosphor layer having a stimulable phosphor (CsBr: Eu) on the surface of a support by using the vapor deposition device shown in FIG. 4 (where θ1 = 5 degrees and θ2 = 5 degrees are set). Was formed.

Using the vapor deposition apparatus shown in FIG. 4, a slit made of aluminum was used, and the distance d between the support and the slit was d.
Is 60 cm, vapor deposition is carried out while transporting the support in a direction parallel to the support, and the thickness of the stimulable phosphor layer is 300.
It was adjusted to be μm.

In the vapor deposition, the support is placed in the vapor deposition device, and then the phosphor material (CsBr: Eu) is used.
Was deposited in a tungsten vapor deposition plate as a vapor deposition source, and an electric current was passed to vapor-deposit the vapor deposition plate while adjusting the heating temperature.

After that, the inside of the vapor deposition apparatus was once evacuated, N ₂ gas was introduced, the degree of vacuum was adjusted to 0.133 Pa, and the vapor deposition was performed while maintaining the temperature of the support (also referred to as the substrate temperature) at about 350 ° C. did. The vapor deposition was terminated when the film thickness of the stimulable phosphor layer reached 300 μm, and then this phosphor layer was heat-treated at a temperature of 400 ° C. In an atmosphere of dry air,
A radiation image conversion panel sample 1 (comparative example) having a structure in which the phosphor layer was sealed was obtained by encapsulating the periphery of the protective layer having the support and borosilicate glass with an adhesive.

The evaporation source heating temperature during vapor deposition was 638.degree. In the production of the radiation image conversion panel sample 1 (comparative example), the conditions are the same as those shown in Table 1, except that
Radiation image conversion panel samples 2, 3, 4 and 5 were prepared respectively. The amount of Eu used is 5 × 10 ⁻⁴ g, and the amount of Gd used is 5 × 10 ⁻⁴ g.

Radiation image conversion panel samples 1 to 5 thus obtained
Was evaluated as follows.

<< Evaluation of Luminance >> Luminance is measured by Re manufactured by Konica Corporation.
Evaluation was performed using gius350.

X-rays were emitted from a tungsten tube at 80 kVp,
After irradiation at 10 mAs with a distance of 2 m between the radiation source and the plate, the plate was placed on the Regius 350 and read. Relative evaluation was performed based on the electric signal from the obtained photomul. The brightness of Sample 2 was set to 1.0, and the subsequent values were represented by their relative values.

<< Evaluation of Sharpness >> The sharpness of the radiation image conversion panel sample was evaluated by obtaining the modulation transfer function (MTF).

MTF is a radiographic image conversion panel sample with C
After attaching the TF chart, the radiation image conversion panel sample was exposed to 80 mVp of X-ray at 10 mR (distance to the subject:
After irradiation for 1.5 m), a CTF chart image was obtained by scanning and reading using a semiconductor laser having a diameter of 100 μm (680 nm: power on the panel: 40 mW). The values in the table are shown as a value (%) obtained by adding MTF values of 2.0 lp / mm. The obtained results are shown in Table 1 below.

<< Measurement of Instantaneous Afterglow Ratio and Stimulated Afterglow Ratio >> Evaluation Method For stimulated luminescence, the signal value is read and measured in the same manner as the luminance evaluation.

For the measurement of the photostimulable afterglow ratio, half the laser scanning was carried out at the time of laser scanning, and the value (a) of the luminance after scanning was obtained.
Half of the laser was turned off, and after laser off, the value (b) after 300 msec of X-ray bombardment was measured and the ratio of luminance was taken as the photostimulable afterglow ratio.

Stimulated afterglow ratio (%) = (a / b) × 100 X-ray / plate / Photomar (R manufactured by Hamamatsu Photonics KK
In the configuration of 1305), the signal immediately after X-ray bombardment was set to 1.0, and the signal after 300 msec of X-ray bombardment was measured (c), and the ratio was defined as the instantaneous afterglow ratio.

Instantaneous afterglow ratio (%) = (c / 1.0) × 1
00 <Measurement of full width at half maximum of emission wavelength> The full width at half maximum of emission wavelength of the phosphor was measured using an absorption spectrum device.

When the full width at half maximum is wide, the crystal collapses, and when the full width at half maximum is narrow, a columnar crystal in which the crystal does not collapse is obtained, light scattering does not occur in the columnar crystal, and the sharpness is excellent.

The numbers below the main activator Eu in the table represent the evaporation source heating temperature during vapor deposition.

[0125]

[Table 1]

[0126]

As demonstrated in the examples, the radiation image conversion panel and the method for manufacturing the radiation image conversion panel according to the present invention have a small afterglow, a narrow half-width of the emission wavelength of the phosphor, a high brightness and a high sharpness. Property is obtained and it has an excellent effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a stimulable phosphor layer having columnar crystals formed on a support.

FIG. 2 is a diagram showing how a stimulable phosphor layer is formed on a support by a vapor deposition method.

FIG. 3 is a schematic diagram showing an example of a configuration of a radiation image conversion panel of the present invention.

FIG. 4 is a schematic view showing an example of a method for producing a stimulable phosphor layer on a support by vapor deposition.

[Description of Reference Signs] 11 support 12 stimulable phosphor layer 13 columnar crystal 14 gap 15 formed between columnar crystals 15 support holder 21 radiation generator 22 subject 23 radiation image conversion panel 24 photostimulation excitation light source 25 conversion Photoelectric conversion device 26 for detecting stimulated fluorescence emitted by the panel 26 Image reproducing device 27 Image display device 28 Filter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/85 C09K 11/85 G01T 1/00 G01T 1/00 BF term (reference) 2G083 AA03 BB01 CC03 DD02 DD11 EE02 EE03 EE04 4H001 CA04 CA05 CA08 CF01 XA00 XA03 XA04 XA09 XA11 XA12 XA13 XA17 XA19 XA20 XA21 XA28 XA29 XA30 XA31 XA35 XA37 XA38 XA55 YAYA YA47 YA49 YA49 YA49 YA56 YA56 YA47

Claims (6)

[Claims] 1. A radiation image conversion panel having a stimulable phosphor layer on a support, wherein at least one stimulable phosphor layer is 50 μm by a vapor phase method (also referred to as a vapor phase deposition method).
A radiation image conversion panel, which is formed to have a film thickness of m to 1 mm and which contains two or more kinds of rare earth compounds uniformly in the phosphor composition. 2. The stimulable phosphor layer, wherein the at least one stimulable phosphor layer contains a stimulable phosphor having an alkali halide represented by the following general formula (1) as a matrix. The layer has a thickness of 50 μm to 1 by a vapor deposition method (also referred to as vapor deposition method)
The radiation image conversion panel according to claim 1, wherein the radiation image conversion panel is formed to have a thickness of mm. Formula ^{(1) M 1 X · aM} 2 X '2 · bM 3 X "3: eA wherein at least one alkali metal M ¹ is Li, Na, K, selected from atoms of Rb and Cs Is an atom, and M ² is Be, Mg, Ca, Sr, Ba, Zn, C
d is at least one divalent metal atom selected from Cu and Ni atoms, and M ³ is Sc, Y, La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga, and at least one trivalent metal atom selected from In, X, X ′, and X ″ are F, Cl, Br, and I atoms. Is at least one kind of halogen atom selected from, A is Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, N
d, Yb, Er, Gd, Lu, Sm, Y, Tl, Na,
At least 2 selected from each atom of Ag, Cu and Mg
It is at least one kind of metal atom, and a, b, and e each represent a numerical value in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <e ≦ 0.2. ] 3. The radiation image conversion panel according to claim 1, wherein at least one rare earth compound among the two or more rare earth compounds in the phosphor composition has a Cs atom. 4. The radiation image conversion panel according to any one of claims 1 to 3, wherein the amount of photostimulable afterglow after 300 msec of X-ray bombardment is 0.0001 to 0.1%. 5. The radiation image conversion panel according to claim 4, wherein the amount of instantaneous afterglow after 300 msec of X-ray exposure is 0.0001 to 0.01%. 6. A method of manufacturing a radiation image conversion panel, which comprises manufacturing the radiation image conversion panel according to claim 1 in an atmosphere of dry air.