JP2003270395A - Radiogram conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiogram conversion panel having excellent rigidity, capable of preventing decline of phosphor brightness and preventing generation of horizontal stripes caused by vibration at the image reading time. <P>SOLUTION: This radiogram conversion panel having a stimulable phosphor layer on a support is characterized by providing an alkali dissolution prevention layer between the support and the stimulable phosphor layer, and using a glass support as the support. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a radiation image conversion panel.

[0002]

2. Description of the Related Art In recent years, a method of forming a radiation image by a radiation image conversion panel using a stimulable phosphor has been used.

This is described, for example, in US Pat. No. 3,859,
A radiation image conversion panel having a stimulable phosphor layer formed on a support as disclosed in JP-A No. 527 and JP-A-55-12144 is used. Radiation that has passed through the subject is applied to the stimulable phosphor layer of this radiation image conversion panel, and radiation energy corresponding to the radiation transmittance of each part of the subject is accumulated in the stimulable phosphor layer to form a latent image (accumulated image). By scanning the photostimulable phosphor layer with photostimulable excitation light (laser light is used), the radiation energy accumulated in each part is emitted and converted into light, and the intensity of this light is read. And get the image. This image may be reproduced on various displays such as a CRT, or may be reproduced as a hard copy.

The stimulable phosphor layer of the radiation image conversion panel used in this radiation image conversion method has a high radiation absorption rate and a high light conversion rate, and has good image graininess and high sharpness. Required.

Usually, the film thickness of the stimulable phosphor layer must be increased in order to increase the radiance, but if it is too thick, the scattering of stimulated emission between the stimulable phosphor particles will occur. Therefore, there is a limit that light emission does not come out to the outside.

Further, the sharpness is improved as the stimulable phosphor layer is made thinner, but if it is too thin, the decrease in luminance becomes large.

Regarding the graininess, the graininess of the image is determined by the spatial fluctuation of the radiation quantum number (quantum mottle), the structural disorder of the stimulable phosphor layer of the radiation image conversion panel (structural mottle), or the like. Therefore, as the layer thickness of the stimulable phosphor layer becomes thin, the number of radiation quantum absorbed in the stimulable phosphor layer decreases and mottle increases, or structural disorder becomes apparent and structural mottle increases. As a result, the image quality is degraded.
Therefore, in order to improve the graininess of the image, the stimulable phosphor layer needs to be thick.

As described above, the image quality and the brightness of the radiation image conversion method using the radiation image conversion panel are determined by various factors. Various studies have been conducted so far in order to improve the brightness and the image quality by adjusting a plurality of factors relating to the brightness and the image quality.

Among them, as a means for improving the sharpness of a radiation image, for example, an attempt has been made to improve the brightness and the sharpness by controlling the shape itself of the stimulable phosphor to be formed.

As one of these attempts, for example, as in JP-A-61-242497, a fine stimulable phosphor formed by depositing a stimulable phosphor on a support having a fine uneven pattern is formed. There is a method of using a stimulable phosphor layer formed of a pseudo columnar block.

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 and further A method of using a radiation image conversion panel having a developed photostimulable phosphor layer, and further, JP-A-Sho 6
A method of using a radiation image conversion panel in which a stimulable phosphor layer formed on the surface of a support is cracked from the surface side thereof to form a pseudo column, as described in JP-A-2-39737, and further, As described in JP-A-62-110200, a method of forming a stimulable phosphor layer having cavities on the upper surface of a support by vapor deposition and then growing the cavities by heat treatment to form cracks has been proposed. .

Further, in JP-A-2-58000,
There has been proposed a radiation image conversion panel having a stimulable phosphor layer on a support, which is formed by a vapor deposition method, and has elongated columnar crystals having a certain inclination with respect to the normal direction of the support.

In all of these attempts to control the shape of the photostimulable phosphor layer, the photostimulable phosphor layer is formed into a columnar shape so that the photostimulable excitation light (or the photostimulated light emission) is directed in the lateral direction. Since the diffusion can be suppressed (it reaches the surface of the support while repeating the reflection at the crack (columnar crystal) interface), the sharpness of the image due to the stimulated emission can be remarkably increased.

However, these vapor-phase growth (deposition)
Even in the radiation image conversion panel having the stimulable phosphor layer formed by the above method, it cannot be said that the relationship between the brightness and the sharpness has sufficient characteristics as described above, and further improvement is required.

In a radiation image conversion panel having a stimulable phosphor layer formed by these vapor phase growth (deposition) methods, an attempt to further improve the image quality, particularly sharpness, is made in JP-A-1-1319898. It is being appreciated. This is to suppress reflection and refraction at the layer interface in the radiation image conversion panel by combining the phosphor layer made of the quasi-columnar stimulable phosphor crystal and the low refractive index layer to further improve the image quality. .

In the reading step in the radiation image recording / reproducing method, generally, excitation light is irradiated from one surface side of the radiation image conversion panel, and the stimulated emission light (stimulated emission light) emitted from the phosphor particles is converted into the excitation light. A method is used in which a light-collecting guide provided on the irradiation side is used to take out, photoelectrically convert, and read. However, when it is desired to extract as much stimulable light emitted from the stimulable phosphor particles as possible, or the accumulated image of the radiation energy formed in the stimulable phosphor layer has an energy intensity in the depth direction in the layer. When you want to obtain the change of the energy intensity distribution as radiation image information when the distribution is changing, use the method of concentrating stimulated light from both sides of the radiation image conversion panel (double-sided condensing reading method). Sometimes. This double-sided condensing reading method is described in, for example, JP-A-55-87970.

Further, in the radiation image conversion panel having the stimulable phosphor layer using the alkaline earth metal type phosphor formed by the vapor phase growth (deposition) described above, when glass is used as the support. However, there is a problem in that the alkaline component contained in the glass is eluted during the heating step to lower the phosphor brightness. Also, when the glass thickness becomes thin (for example,
(Less than 0.3 mm) There is a problem in terms of rigidity and generation of lateral stripes due to vibration during image reading.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation image in which there is no reduction in phosphor brightness (hereinafter, also referred to as sensitivity), which is excellent in rigidity, and which does not cause lateral stripes due to vibration during image reading. To provide a conversion panel.

[0019]

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, an alkali elution preventing layer is provided between the support and the stimulable phosphor layer, and the support is a glass support. Radiation image conversion panel.

2. 2. The radiation image conversion panel as described in 1 above, wherein the glass support has a thickness of 0.3 mm or more.

3. 2. The radiation image conversion panel as described in 1 above, wherein the glass support has a thickness of 0.5 mm or more.

4. 2. The radiation image conversion panel as described in 1 above, wherein the glass support has a thickness of 0.7 mm or more.

5. The thickness of the alkali elution prevention layer is 10
Any one of 1 to 4 above, which is 0 Å or more
The radiation image conversion panel according to item.

6. The alkali elution prevention layer has a thickness of 50.
Any one of 1 to 4 above, which is 0 Å or more
The radiation image conversion panel according to item.

7. The thickness of the alkali elution prevention layer is 80
Any one of 1 to 4 above, which is 0 Å or more
The radiation image conversion panel according to item.

8. 8. The radiation image conversion panel according to any one of 1 to 7 above, wherein the alkali elution prevention layer contains at least one compound selected from SiO ₂ and Si ₃ N ₄ .

9. The stimulable phosphor layer has the general formula (1)
And a stimulable phosphor layer formed by a vapor growth method (also referred to as a vapor deposition method) to have a film thickness of 50 μm or more. 1 to do
The radiation image conversion panel according to any one of items 1 to 8.

10. M ¹ in the general formula (1) is K, R
10. The radiation image conversion panel as described in 9 above, which is at least one kind of alkali metal atom selected from each atom of b and Cs.

11. X in the general formula (1) is at least one halogen atom selected from Br atom and I atom, The radiation image conversion panel as described in 9 or 10 above.

12. M ² in the general formula (1) is Be,
12. The radiation image conversion panel according to any one of 9 to 11 above, which is at least one divalent metal atom selected from each atom of Mg, Ca, Sr, and Ba.

13. M ³ in the general formula (1) is Y or C.
13. The radiation according to any one of 9 to 12 above, which is at least one trivalent metal atom selected from the atoms of e, Sm, Eu, Al, La, Gd, Lu, Ga and In. Image conversion panel.

14. B in the general formula (1) is 0 ≦ b ≦
10 ^-2 , any one of 9 to 13 above
The radiation image conversion panel according to item.

15. A in the general formula (1) is Eu,
9 to 1 characterized in that it is at least one metal atom selected from each atom of Ce, Sm, Tl and Na.
4. The radiation image conversion panel according to any one of 4 above.

16. 16. The radiation image conversion panel according to any one of 1 to 15 above, wherein the stimulable phosphor has columnar crystals.

17. 17. The radiation image conversion panel as described in 16 above, wherein columnar crystals have a stimulable phosphor represented by the general formula (2) as a main component.

The present invention will be described in more detail below. The support of the radiation image conversion panel of the present invention will be described.

The support of the radiation image conversion panel of the present invention is a glass support, and the glass thickness is preferably 0.3 mm or more, more preferably 0.5 mm or more, and further preferably 0.7 mm or more. . The upper limit is 5 due to handling.
mm is preferred.

Within the above range, the rigidity is good, and horizontal stripes are not generated due to vibration during image reading, which is suitable for image reading.

Specific examples of the glass include borosilicate glass (BLC (manufactured by Nippon Electric Glass Co., Ltd.), 7740 (manufactured by Corning Co.), tempax (manufactured by Shot Company)), low alkali glass (AL (manufactured by Asahi Glass Co., Ltd.), D263 (manufactured by Schott) and soda glass (As (manufactured by Asahi Glass)) are preferable.

The present invention also provides a radiation image conversion panel in which a stimulable phosphor is formed on a glass support by a vapor deposition method, with an alkali elution between the glass support and a stimulable phosphor layer described later. It is a radiographic image conversion panel characterized by providing an prevention layer.

The thickness of the alkali elution prevention layer is 100Å
It is preferably at least 500 l, more preferably at least 500 l, particularly preferably at least 800 l. The thicker the thickness, the better, but from a practical point of view, the upper limit is 600.
It is less than 0Å.

Although a cross-sectional view of the radiation image conversion panel layer having the alkali elution preventing layer is not shown, for example,
In FIG. 1A, an alkali elution preventing layer can be provided between the support 1 and the stimulable phosphor layer b having the columnar crystals 2 so as to have the above thickness.

The alkali elution-preventing layer may be provided on the glass support by any of a coating method and a vapor deposition method (vapor layer deposition method). In the present invention, the vapor deposition method (vapor layer deposition method) is used. Is preferred.

In the above vapor deposition method, the temperature of the glass support is preferably not higher than 250 ° C., and the degree of vacuum is preferably 1.3 × 10 ⁻³ Pa or less.

In the present invention, the alkali elution preventive layer is vapor-deposited on a support, and the stimulable phosphor described later is continuously vapor-deposited on the alkali elution preventive layer under the following conditions. An exhaustible phosphor layer may be formed.

In the present invention, when the above alkali elution preventing layer is provided and the thickness of the layer is within the above range, alkali elution from the glass support during the heating step is eliminated, and the phosphor sensitivity which is the object of the present invention. Is preferable, and the effect of the present invention is further exhibited, which is preferable.

Further, the alkali elution preventing layer is SiO ₂
And having at least one compound selected from Si ₃ N ₄ is more preferable from the viewpoint of particularly exhibiting the effects of the present invention.

Next, the stimulable phosphor layer of the present invention will be described. FIG. 1 is a schematic view showing an example of a columnar crystal shape formed on the support of the present invention. In a) and b) of FIG. 1, 2 is a columnar crystal of a stimulable phosphor formed on a support 1 by a vapor deposition method, and its crystal tip passes through the center of the crystal growth direction. The angle (θ) formed by the perpendicular 3 and the tangent 4 of the crystal tip cross-section is preferably 20 ° to 80 °, more preferably 40 ° to 80 °.

1A) is an example in which the columnar crystal has a sharp corner at the center thereof, and FIG. 1B) shows that the tip of the columnar crystal has a certain inclination, and This is an example of having a sharp corner on the side surface.

In the present invention, the tip shape is not particularly limited in terms of the angle (θ) specified in the present invention,
For example, it can be obtained by appropriately selecting the temperature of the support during the crystal growth, the degree of vacuum, the crystal growth rate, the type of the stimulable phosphor, and the like by the vapor deposition method described below.

Further, in the present invention, the average crystal diameter of the columnar crystals is preferably 0.5 to 50 μm, more preferably 1 to 50 μm.

By setting the average crystal diameter of the columnar crystals defined above, the haze ratio of the stimulable phosphor layer b can be reduced, and as a result, excellent sharpness can be realized.

The average crystal diameter of the columnar crystals is the average value of the circle-converted diameters of the cross-sectional areas of the columnar crystals when the columnar crystals are observed from a plane parallel to the support, and at least 100 or more columnar crystals. Is calculated from the electron micrograph including in the visual field.

The columnar crystal diameter is influenced by the temperature of the support, the degree of vacuum, the vapor flow incident angle, etc., and by controlling these, a columnar crystal having a desired thickness can be formed.

For example, the temperature of the support tends to become thinner as the temperature becomes lower, but if it is too low, it becomes difficult to maintain the columnar state. As the temperature of the preferable support,
100-300 degreeC, More preferably, it is 150-27.
It is 0 ° C. The incident angle of the steam flow is preferably 0 to 5 °. The degree of vacuum is 1.3 × 10 ^-1 Pa
The following is preferable.

Next, the vapor deposition method will be described in detail. Examples of the stimulable phosphor that can be used in the stimulable phosphor layer formed by the vapor deposition method include, for example, JP-A-48-
BaSO are described in JP 80487 _4: phosphor represented by Ax, MgSO described in JP 48-80488
₄ : a phosphor represented by Ax, a phosphor represented by SrSO ₄ : Ax described in JP-A-48-80489,
Na ₂ S described in JP-A-51-29889
Mn, Dy and Tb in O ₄ , CaSO ₄ and BaSO ₄ etc.
Of at least one of the above-mentioned compounds, JP-A-52-3
BeO, LiF, MgSO described in No. 0487
₄ , phosphors such as CaF ₂ , phosphors such as Li ₂ B ₄ O ₇ : Cu, Ag described in JP-A-53-39277,
Li ₂ O described in JP-A-54-47883
(Be ₂ O ₂ ) x: phosphors such as Cu and Ag, SrS: Ce, described in US Pat. No. 3,859,527
Examples include phosphors represented by Sm, SrS: Eu, Sm, La ₂ O ₂ S: Eu, Sm and (Zn, Cd) S: Mnx.

Further, a ZnS: Cu, Pb phosphor described in JP-A-55-12142, whose general formula is BaO.
Examples include barium aluminate phosphors represented by xAl ₂ O ₃ : Eu and alkaline earth metal silicate phosphors represented by the general formula of M (II) O.xSiO ₂ : A.

Further, it is described in JP-A-55-12143.
The general formula is (Ba_1-xyMg_xCa_y) F_x: Eu²⁺
Alkaline earth fluorohalide phosphor represented by
The general formula described in Kaisho 55-12144 is Ln.
OX: phosphor represented by xA, JP-A-55-12145
The general formula described in No._1-xM (II)_x)
F _x: YA phosphor, JP-A-55-84389
The general formula described in No. is BaFX: xCe, yA
Phosphors represented, described in JP-A-55-160078
The general formula is represented by M (II) FX · xA: yLn
Rare earth element activated divalent metal fluorohalide phosphor,
General formula ZnS: A, CdS: A, (Zn, Cd) S: A,
Phosphor represented by X, described in JP-A-59-38278
A phosphor represented by any one of the following general formulas, General formula xM₃(PO_Four)₂・ NX₂: YA xM₃(PO_Four)₂: YA What is described below in JP-A-59-155487
A phosphor represented by the general formula.

A phosphor represented by the general formula nReX ₃ .mAX ' ₂ : xEu nReX ₃ .mAX' ₂ : xEu, ySm, the following general formula described in JP-A-61-272087, M (I) X · aM (II) X ′ ₂ · bM (III) X ″ ₃ : c
Alkali halide phosphor represented by A and JP-A-61-2
No. 28400, the general formula M (I) X: xB
Examples thereof include bismuth-activated alkali halide phosphors represented by i. In particular, alkali halide phosphors are vapor deposited,
A columnar stimulable phosphor layer can be easily formed by a method such as sputtering, which is preferable.

Next, the stimulable phosphor represented by the general formula (1) of the present invention will be described. In the stimulable phosphor represented by the general formula (1) of the present invention, M ^I is N
a, K, Rb, and Cs, which represent at least one alkali metal atom selected from each atom, among which Rb and Cs
At least one kind of alkaline earth metal atom selected from each atom is preferable, and Cs atom is more preferable.

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, Ga, Ce, T
m, Dy, Pr, Ho, Nd, Yb, Er, Gd, L
It is at least one metal atom selected from each atom of u, Sm, 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 an atom of at least one halogen selected from the atoms 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 photostimulable 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, NaCl, NaBr, NaI, KF, K
Cl, KBr, KI, RbF, RbCl, RbBr, R
At least one compound or two or more compounds selected from bI, CsF, CsCl, CsBr, and CsI is 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 (I),
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 and the like.

Next, the obtained phosphor raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace.

A firing temperature of 300 to 1000 ° C. is suitable. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature, etc., but generally 0.5 to 6 hours is appropriate.

The firing atmosphere is a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide gas atmosphere containing a small amount of carbon monoxide, a neutral atmosphere such as a nitrogen gas atmosphere, an argon gas atmosphere, or a small amount of oxygen. A weakly oxidizing atmosphere containing gas is preferred.

After firing once under the above firing conditions, the fired product is taken out of the electric furnace and crushed. After that, the fired product powder is charged again into the heat resistant container and placed in the electric furnace, and the same firing as described above is performed. Rebaking under the conditions is preferable because the emission brightness of the phosphor can be further increased.

When the calcined product is cooled to room temperature from the calcining temperature, the desired phosphor can be obtained by removing the calcined product from the electric furnace and allowing it to cool in the air. You may cool in a weak reducing atmosphere or a neutral atmosphere.

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 phosphor obtained is stimulated. The emission brightness can be further increased.

The stimulable phosphor layer of the present invention is characterized by being formed by a 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 and other methods 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, a 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 vapor deposition, it is preferable that 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. After forming the stimulable phosphor layer on the protective layer,
You may take the procedure of providing a support body.

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 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 / minute, the productivity of the radiation image conversion panel of the present invention is low, 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 vapor deposition method, sputtering method, etc., since the binder does not exist, 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 kind of the stimulable phosphor, but is 50 μ from the viewpoint of obtaining the effect of the present invention.
It is preferably m to 1 mm, more preferably 10
0 to 600 μm, more preferably 300 to 600
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, and more preferably, 150 ° C or higher, particularly preferably 150
~ 400 ° C.

The stimulable phosphor layer of the radiation image conversion panel of the present invention is preferably formed by vapor-phase growth of the stimulable phosphor represented by the general formula (1) on a support. ,
More preferably, the stimulable phosphor forms columnar crystals during layer formation.

In order to form a columnar stimulable phosphor layer by a method such as vapor deposition or sputtering, the compound represented by the above general formula (1) (stimulable phosphor) is used. Among them, CsBr is used. System phosphors are particularly preferably used.

Further, in the present invention, it is preferable that the columnar crystal has a stimulable phosphor represented by the following general formula (2) as a main component.

General Formula (2) CsX: A In the general formula (2), X represents Br or I, and A is E.
represents u, In, Tb or Ce.

As a method for forming a phosphor layer on a glass support (hereinafter, also simply referred to as a support) by a vapor deposition method, vapor of a stimulable phosphor or the raw material thereof is supplied and vapor deposition or the like is performed. A stimulable phosphor layer composed of independent elongated columnar crystals can be obtained by a vapor growth (deposition) method.

In these cases, it is preferable that the distance between the shortest part of the support and the crucible is usually 10 to 60 cm in accordance with the average range of the stimulable phosphor.

The stimulable phosphor serving as an evaporation source is uniformly dissolved, or molded into a crucible by pressing or hot pressing. At this time, it is preferable to perform degassing treatment. The method of evaporating the stimulable phosphor from the evaporation source is performed by scanning an electron beam emitted by an electron gun, but it can be evaporated by a method other than this.

The evaporation source does not necessarily have to be a stimulable phosphor, and may be a mixture of stimulable phosphor raw materials.

Further, the matrix of the phosphor may be doped with an activator later. For example, after vapor-depositing only the base material RbBr, the activator Tl may be doped.
That is, since the crystals are independent, it is possible to dope sufficiently even if the film is thick, and crystal growth does not easily occur.
This is because F does not decrease.

Doping can be performed by a thermal diffusion or ion implantation method of a doping agent (activator) in the formed base layer of the phosphor.

The size of the gap between the columnar crystals is 30.
It is preferably not more than μm, more preferably not more than 5 μm. That is, when the gap exceeds 30 μm, the scattering of laser light in the phosphor layer increases and the sharpness decreases.

Next, the formation of the stimulable phosphor layer of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing a state in which a stimulable phosphor layer is formed on a support by vapor deposition. The stimulable phosphor vapor stream 16 is used as an incident angle of 0 to 5 with respect to the normal direction of the support surface. A columnar crystal is formed by incidence in the range of °.

The stimulable phosphor layer thus formed on the support has no directivity because it does not contain a binder, 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.

In addition, the gaps between the columnar crystals may be filled with a filler such as a binder to reinforce the stimulable phosphor layer.
It may be filled with a substance having a high light absorption, a substance having a high light reflectance, etc., thereby providing the above-mentioned reinforcing effect and reducing the light diffusion in the lateral direction of the stimulable excitation light incident on the stimulable phosphor layer. It is valid.

A substance having a high reflectance means a stimulated excitation light (500
Up to 900 nm, particularly 600 to 800 nm), which has a high reflectance, for example, 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.

From the viewpoint of obtaining a radiation image conversion panel having high sensitivity, the reflectance of the stimulable phosphor layer of the present invention is preferably 20% or more, more preferably 30% or more, and particularly preferably. It is 40% or more. The upper limit is 1
It is 00%.

A substance having a high reflectance means a stimulated excitation light (500
Up to 900 nm, particularly 600 to 800 nm), which has a high reflectance, for example, 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.

In the present invention, the reflectance of the stimulable phosphor layer is measured when a mirror surface treatment (for example, vapor deposition) that reflects light such as aluminum is performed on the substrate.

Here, the reflectance can be measured using the following measuring device under the same measuring conditions.

Equipment: HITACHI 557 type, Spec
trophotometer (Measurement condition) Measurement light wavelength: 680 nm Scan speed: 120 nm / min Number of repetitions: 10 times Response: Automatic setting White pigments can also reflect stimulated emission. White pigment
As TiO₂(Anatase type, rutile type), Mg
O, PbCO₃・ Pb (OH)₂, BaSO_Four, Al
₂O₃, M (II) FX (where M (II) is Ba, Sr and
At least one of Ca, X is Cl, and Br
Is at least one of the ), CaCO ₃, Zn
O, Sb₂O₃, SiO₂, ZrO₂, Lithopone (BaSO
_Four・ ZnS), magnesium silicate, basic silicate salts, salts
Examples include basic lead phosphate and aluminum silicate. this
These white pigments have strong hiding power and high refractive index, so
Easily stimulated emission by reflecting or refracting
Scatters and remarkably increases the sensitivity of the obtained radiation image conversion panel
Can be improved.

As the substance having a high light absorptivity, for example, carbon black, chromium oxide, nickel oxide, iron oxide or 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 Fast Blue 3G (made by Hoechst), Estrol Brill Blue N-3RL (made by Sumitomo Chemical), and D & C Blue No. 1
(Manufactured by National Aniline), Spirit Blue (manufactured 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.
In addition, the color index No. 24411, 23160,
74180, 74200, 22800, 23154, 2
3155, 24401, 14830, 15050, 15
760, 15707, 17941, 74220, 134
25, 13361, 13420, 11836, 7414
Organic metal complex salt colorants such as 0, 74380, 74350, 74460 are also included. Inorganic colorants include ultramarine blue, cobalt blue, cerulean blue, chromium oxide, TiO
_2- ZnO-Co-NiO-based pigments may be mentioned.

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 procedure for forming the stimulable phosphor layer on the separately formed protective layer may be performed. Materials for the protective layer include cellulose acetate, nitrocellulose, polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride,
Ordinary protection of nylon, polytetrafluoroethylene, polytrifluoride-ethylene chloride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, etc. A layering material is used. Alternatively, a transparent glass substrate can be used as the protective layer. In addition, this protective layer is a vapor deposition method,
By sputtering, etc., SiC, SiO ₂ , Si
N, may be formed by laminating an inorganic material such as Al ₂ O _3. The layer thickness of these protective layers is generally 0.1 to 200.
About 0 μm is preferable.

FIG. 3 is a schematic view showing an example of the configuration of the radiation image conversion panel and the radiation image reading device 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 of obtaining a radiation transmission image of a subject, the radiation generator 21 is not particularly necessary when the subject 22 itself emits radiation.

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 irradiated with the radiation R, the radiation R is transmitted according to changes 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 incident on the radiation image conversion panel 23. The incident transmission image RI is absorbed by the stimulable phosphor layer of the radiation image conversion panel 23, whereby a number of electrons and / or holes proportional to the amount of radiation absorbed in the stimulable phosphor layer is generated. Occurs, which accumulates 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. That is, by irradiating the stimulable phosphor layer with a stimulable excitation light source 24 that irradiates light in the visible or infrared region, electrons and / or holes accumulated at the trap level are expelled, and the accumulated energy is stimulated to emit light. To release it. 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 a photoelectric conversion device 25 such as a photomultiplier tube, reproduced by an image reproducing device 26 as an image, and displayed by the image display device 27. The image reproducing device 26 not only reproduces an electric signal as an image signal, but also performs so-called image processing and image calculation,
It is more effective to use one that can store and save images.

Further, when excited by light energy, it is necessary to separate the reflected light of the photostimulable excitation light and the photostimulated luminescence emitted from the photostimulable phosphor layer, 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 3
0 to 500 nm, while the stimulated excitation wavelength range is 500
Since it is ~ 900 nm, the above conditions are satisfied at the same time,
Recently, the downsizing of diagnostic equipment has progressed, and a semiconductor laser that has a high output as an excitation wavelength used for image reading of a radiation image conversion panel and that can be easily made compact is preferred, and the wavelength of the laser light is 680 nm. 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.

That is, each of the stimulable phosphors of the present invention emits light having a main peak at 500 nm or less, and it is easy to separate the stimulable excitation light and matches well with the spectral sensitivity of the photoreceiver. As a result of being able to receive light, 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, the use of laser light simplifies the optical system, and since the intensity of stimulated excitation light can be increased, the stimulated emission efficiency can be increased, and more preferable results can be obtained.

In the present invention, the laser diameter with which the stimulable phosphor layer is irradiated is preferably 100 μm or less, more preferably 80 μm or less.

As the laser, a He-Ne laser,
He-Cd laser, Ar ion laser, Kr ion laser, N ₂ laser, YAG laser and its second
There are harmonics, ruby lasers, semiconductor lasers, various dye lasers, metal vapor lasers such as copper vapor lasers, and the like. Normally, a continuous wave laser such as a He-Ne laser or an Ar ion laser is desirable, but a pulsed laser can be used if the scanning time of one pixel of the panel is synchronized with the pulse. Further, in the case of the method of separating by utilizing the delay of light emission as shown in JP-A-59-22046 without using the filter 28, the pulse oscillation laser is used rather than the modulation using the continuous oscillation laser. It is preferable to use.

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.

As the filter 28, the photostimulable luminescence emitted from the radiation image conversion panel 23 is transmitted and the photostimulation excitation light is cut off. 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 having a stimulated emission wavelength of 300 to 500 nm in m, examples of the filter include C-39, C-40, V-40 and V-4 manufactured by Toshiba Corporation.
2, V-44, Corning 7-54, 7-59, Spectrofilm BG-1, BG-3, BG-2.
5, BG-37, BG-38 and other purple to blue glass filters 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.

[0130]

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

Example << Preparation of Radiation Image Conversion Panel Samples 1 to 8 (Indicated as Samples 1 to 8 in Table 1) >> Under the conditions shown in Table 1,
On a 0.3 mm thick soda glass (manufactured by Asahi Glass Co., Ltd.) support, a stimulable phosphor (C
A stimulable phosphor layer having sBr: Eu) 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.
Was 60 cm, vapor deposition was carried out while transporting the glass support in a direction parallel to the glass support, and the thickness of the stimulable phosphor layer was adjusted to 300 μm.

In the vapor deposition, the support is placed in the vapor deposition device, and then the phosphor material (CsBr: Eu) is used.
Was used as a vapor deposition source and was put into a crucible that was press-molded and water-cooled.

Then, the inside of the vapor deposition device is evacuated once, and then N 2
_After introducing ₂ gases and adjusting the vacuum degree to 0.133 Pa,
Deposition was performed while maintaining the temperature of the support (also referred to as the substrate temperature) at about 240 ° C.

When the film thickness of the stimulable phosphor layer reached 300 μm, vapor deposition was terminated to obtain a stimulable phosphor layer. A radiation image conversion panel sample 1 having a structure in which the stimulable phosphor layer was sealed by enclosing the periphery of the protective layer made of a support and borosilicate glass with an adhesive in an atmosphere of dry air was obtained.

Radiation image conversion panel samples 1 were prepared in the same manner as in the preparation of radiation image conversion panel sample 1, except that the conditions shown in Table 1 were used.

For the alkali elution preventing layer, the compounds shown in Table 1 were used on the soda glass (Asahi Glass Co., Ltd.) support, and the vacuum degree was 1.3 × 10 ⁻³ Pa using the apparatus shown in FIG. ,
While maintaining the temperature of the glass support at 200 ° C., vapor deposition was performed by adjusting the film thickness shown in Table 1.

<< Evaluation of Radiation Image Conversion Panel >> Each of the radiation image conversion panel samples prepared as described above was evaluated for brightness and generation of horizontal stripes according to the following methods.

(Evaluation of Luminance) Each produced radiation image conversion panel sample was uniformly irradiated with X-rays having a tube voltage of 80 kVp, and then the laser beam diameter was 8 from the surface side provided with the phosphor layer.
The semiconductor laser beam (690 nm) of 0 μm was used for scanning and excitation, and photostimulable luminescence emitted from each phosphor layer was received by a photodetector (photoelectron image multiplier with spectral sensitivity S-5), and its intensity was measured. This was defined as luminance, and the radiation image conversion panel sample 1 was set to 1.0 and displayed as a relative value.

(Evaluation of generation of transverse stripes due to vibration) Each sample was subjected to image processing of linear gradation processing with an inclination of 3.0, and then film output was performed using a laser imager with an average optical density of 1.0. This was visually evaluated using a Schaukasten in 5 grades. (1 (bad) to 5 (excellent))

[0141]

[Table 1]

[0142]

As demonstrated in the examples, the radiation image conversion panel according to the present invention has an excellent effect in that the brightness of the phosphor is not lowered, the rigidity is excellent, and the horizontal stripes are not generated due to vibration during image reading. Have.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a columnar crystal shape formed on a support.

FIG. 2 is a schematic view showing an example of how a stimulable phosphor layer is formed on a support by vapor deposition.

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

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

[Explanation of symbols] 1 support 2 columnar crystals 3 Perpendicular line passing through the center of crystal growth direction 4 Tangent line of crystal tip cross section 5 Crystal size of columnar crystals 15 Support holder 21 Radiation generator 22 subject 23 Radiation image conversion panel 24 Excited excitation light source 25 Photoelectric conversion device 26 Image playback device 27 Image display device 28 filters

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/61 CPF C09K 11/61 CPF 11/85 11/85 G01T 1/00 G01T 1/00 BF term (Reference) 2G083 AA03 BB01 CC03 CC04 CC08 DD01 DD02 DD11 EE02 EE03 EE07 4H001 CA02 CA04 CA08 CC11 CF01 XA00 XA03 XA04 XA09 XA11 XA12 XA13 XA17 XA19 XA20 XA XAX XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 XA31 YA58 YA62 YA63 YA81

Claims (17)

[Claims] 1. A radiation image conversion panel having a stimulable phosphor layer on a support, wherein an alkali elution preventing layer is provided between the support and the stimulable phosphor layer, and the support is a glass support. A radiation image conversion panel characterized by: 2. The radiation image conversion panel according to claim 1, wherein the glass support has a thickness of 0.3 mm or more. 3. The radiation image conversion panel according to claim 1, wherein the glass support has a thickness of 0.5 mm or more. 4. The radiation image conversion panel according to claim 1, wherein the glass support has a thickness of 0.7 mm or more. 5. The thickness of the alkali elution prevention layer is 100.
It is Å or more, 1 in any one of Claims 1-4 characterized by the above-mentioned.
The radiation image conversion panel according to item. 6. The alkali elution prevention layer has a thickness of 500.
It is Å or more, 1 in any one of Claims 1-4 characterized by the above-mentioned.
The radiation image conversion panel according to item. 7. The thickness of the alkali elution preventing layer is 800.
It is Å or more, 1 in any one of Claims 1-4 characterized by the above-mentioned.
The radiation image conversion panel according to item. 8. The radiation image conversion according to any one of claims 1 to 7, wherein the alkali elution preventing layer contains at least one compound selected from SiO ₂ and Si ₃ N _4. panel. 9. The stimulable phosphor layer contains a stimulable phosphor represented by the following general formula (1), and the stimulable phosphor layer is formed by a vapor phase growth method (both vapor phase deposition method). According to claim 1), the film is formed to have a film thickness of 50 μm or more.
The radiation image conversion panel according to any one of items 1 to 8. 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. At least one halogen atom selected from
Is Eu, Tb, In, Ga, Ce, Tm, Dy, Pr,
Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, T
1, at least one metal atom selected from each of Na, Ag, Cu, and Mg, and a, b, and e are 0 ≦ a <0.5, 0 ≦ b <0.5, 0, respectively. <E ≦ 0.
Represents a numerical value in the range of 2. ] 10. M ¹ in the general formula (1) is K or Rb.
The radiation image conversion panel according to claim 9, wherein the radiation image conversion panel is at least one kind of alkali metal atom selected from the atoms of Cs and Cs. 11. The radiation image conversion panel according to claim 9, wherein X in the general formula (1) is at least one halogen atom selected from Br atom and I atom. 12. M ² in the general formula (1) is Be, M
The radiation image conversion panel according to any one of claims 9 to 11, wherein the radiation image conversion panel is at least one divalent metal atom selected from each of g, Ca, Sr, and Ba atoms. 13. M ³ in the general formula (1) is Y or C.
13. At least one trivalent metal atom selected from each atom of e, Sm, Eu, Al, La, Gd, Lu, Ga, and In, according to any one of claims 9 to 12. Radiation image conversion panel. 14. b in the general formula (1) is 0 ≦ b ≦ 1.
It is 0 ^-2 , 1 in any one of Claims 9-13 characterized by the above-mentioned.
The radiation image conversion panel according to item. 15. A in the general formula (1) is Eu or C.
It is at least 1 sort (s) of metal atom selected from each atom of e, Sm, Tl, and Na, It is characterized by the above-mentioned.
4. The radiation image conversion panel according to any one of 4 above. 16. The radiation image conversion panel according to claim 1, wherein the stimulable phosphor has columnar crystals. 17. The radiation image conversion panel according to claim 16, wherein the columnar crystal has a stimulable phosphor represented by the following general formula (2) as a main component. General formula (2) CsX: A [In formula, X represents Br or I, A is Eu, In, G.
represents a or Ce. ]