JP2002107852A - Radiographic image conversion panel and radiographic image information reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic image conversion panel which is superior damp-proof and generates radiation image of high image quality and a radiation image information reading method. SOLUTION: This radiation image conversion panel has a base, a phosphor layer which is formed by vapor-phase deposition, and a protective layer. Here, the base is formed in the shape of a frame body, having a projection part at its peripheral edge part, and the phosphor layer is formed inside the frame body; and the projection layer is jointed with at least the projection part and the phosphor layer is held airtight and shielded from the outside atmosphere. Furthermore, the radiation image information reading method uses combination of the radiation image conversion panel and a line sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image conversion panel and a radiation image information reading method used in a radiation image recording / reproducing method using stimulable light emission of a stimulable phosphor.

[0002]

2. Description of the Related Art A radiation image recording / reproducing method using a stimulable phosphor is known as an alternative to the conventional radiographic method. This method uses a radiation image conversion panel (a stimulable phosphor sheet) containing a stimulable phosphor, and transmits radiation transmitted through a subject or emitted from a subject to the stimulable phosphor of the panel. The radiation energy stored in the stimulable phosphor is absorbed by the body in a time-series manner by exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. The fluorescent light is emitted as (stimulated emission light), the fluorescence is read photoelectrically to obtain an electric signal, and a radiation image of a subject or a subject is reproduced as a visible image based on the obtained electric signal. After the reading, the panel is prepared for the next photographing after the remaining image is erased. That is, the radiation image conversion panel is used repeatedly.

The radiation image conversion panel used in the radiation image recording / reproducing method has, as a basic structure, a support and a stimulable phosphor layer. However, when the stimulable phosphor layer is self-supporting, a support is not necessarily required. Also, a protective layer is usually provided on the upper surface of the stimulable phosphor layer (the side not facing the support) to protect the phosphor layer from chemical alteration or physical impact. ing.

The stimulable phosphor layer usually comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. However, the stimulable phosphor layer may be composed of only an aggregate of the stimulable phosphor without a binder formed by a vapor deposition method or a sintering method, or may be formed of a stimulable phosphor. It is also known that a polymer substance is impregnated in the gap of the aggregate. In any of these phosphor layers, the stimulable phosphor has a property of exhibiting stimulable emission when irradiated with excitation light after absorbing radiation such as X-rays. The radiation emitted from the subject is absorbed in the stimulable phosphor layer of the radiation image conversion panel in proportion to the amount of the radiation, and the radiation image of the subject or the subject is stored in the panel as an accumulated image of radiation energy ( (Latent image). This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading the stimulated emission light and converting it into an electric signal. Can be realized.

As a method of reading radiation image information emitted as stimulating light, pixel division is performed by scanning with excitation light, and stimulating is performed by a light receiving element such as a photomultiplier tube or a photoconductive element having a wide light receiving surface. Methods for detecting emitted light are known. Then, in order to solve the problems such as the complicated and large-sized device and the long processing time associated with this method, pixel division is performed by a light-receiving element such as a two-dimensional solid-state imaging device or a semiconductor line sensor, and a time-series image is formed by an electric circuit. A method for forming a signal has been proposed. For example, Japanese Patent Publication No. 5-32945 discloses that a radiation image conversion panel is irradiated with light emitted from a fluorescent lamp or the like through a slit to irradiate excitation light in a linear manner (so-called “line excitation”). An apparatus for detecting emitted stimulating light by a line sensor including a large number of solid-state photoelectric conversion elements arranged opposite to an excitation light irradiation portion (so-called “line detection”) is described. According to this apparatus, reading can be performed at high speed, the S / N ratio of the image signal is improved, and the manufacturing and handling of the reading apparatus can be simplified and the cost can be reduced.

As another method of the above-mentioned radiation image recording / reproducing method, Japanese Patent Application No. 11-372978 by the present applicant discloses a stimulable phosphor-containing stimulable phosphor layer (and a radiation-absorbing phosphor layer). A radiation image forming method using a combination of a radiation image conversion panel having a body layer) and a phosphor screen having a radiation absorbing phosphor layer containing a phosphor that absorbs radiation and emits light in the ultraviolet to visible region, and Radiation imaging materials comprising combinations thereof are described. In this method, radiation transmitted through a subject, diffracted or scattered by the subject, or emitted from the subject is first applied to a fluorescent screen or a radiation absorbing phosphor layer of a radiation image conversion panel in an ultraviolet to visible region. After that, the light is accumulated and recorded as a latent image in the stimulable phosphor layer of the panel. Next, the panel is irradiated with excitation light to photoelectrically read the stimulated emission light from the stimulable phosphor layer to convert it into an image signal, and reconstruct an image corresponding to the spatial energy distribution of radiation from the image signal. Make up. The radiation image conversion panel of the present invention, the image forming material used in the above method, that is, a panel containing both a stimulable phosphor and a phosphor that absorbs radiation and emits light in the ultraviolet to visible region, And fluorescent screens.

The radiation image recording / reproducing method (and the radiation image forming method) has many excellent advantages as described above, but the radiation image conversion panel used in this method has as high a sensitivity as possible. It is desired to provide an image with good image quality (sharpness, granularity, etc.).

For the purpose of improving sensitivity and image quality, as described in, for example, Japanese Patent Application Laid-Open No. 62-47600, as a method for manufacturing a radiation image conversion panel, a stimulable phosphor layer is formed by a vapor deposition method. A method of forming by an electron beam evaporation method, which is one of the methods, has been proposed. This method uses a stimulable phosphor or a raw material of a stimulable phosphor as an evaporation source, and irradiates an electron beam with an electron gun to the evaporation source to evaporate the evaporation source.
By scattering and depositing the evaporated substance on the surface of the support, a layer composed of columnar crystals of the stimulable phosphor is formed. The phosphor layer formed by a vapor deposition method such as an electron beam evaporation method does not contain a binder, and is composed of only a stimulable phosphor, and between the columnar crystals of the stimulable phosphor. There are voids (cracks). For this reason, the entrance efficiency of the excitation light and the extraction efficiency of the emission light can be improved, and an image with high sensitivity and high sharpness can be obtained.

However, in general, a phosphor layer formed by a vapor deposition method is not easily covered with a binder such as a resin, so that it is easy to absorb moisture, and the panel is repeatedly used or stored for a long period of time. During this time, the emission characteristics of the phosphor may change (deteriorate), or if the moisture absorption is significant, the phosphor itself may deliquesce. Therefore, it is desired to prevent the phosphor from absorbing moisture as much as possible.

For example, Japanese Utility Model Application Laid-Open No. Sho 62-173100 discloses that a stimulable phosphor layer is formed on the inner side of a support and a protective layer, and the protective layer is formed of an adhesive in order to increase the moisture resistance of the phosphor layer. Describes a radiation image conversion panel in which the entire surface of the phosphor layer is covered with a support and a protective layer by adhering to the phosphor layer and the support using the above method. It has also been proposed to provide a spacer between the support and the protective layer so as to cover the side surface of the phosphor layer.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a radiation image conversion panel which is excellent in moisture resistance and gives a high quality radiation image. Another object of the present invention is to provide a radiation image information reading method capable of obtaining a high-quality radiation image at high speed.

[0012]

The present inventor studied the moisture resistance of a radiation image conversion panel having a phosphor layer formed by a vapor deposition method, and found that the shape of the support was changed to a convex at the periphery. It has been found that the moisture resistance of the panel can be remarkably enhanced by forming a frame having the protective layer bonded to the upper portion of the frame and sealing the phosphor layer.

Accordingly, in a radiation image conversion panel having a support, a phosphor layer formed by a vapor deposition method, and a protective layer in this order, the support has a shape of a frame having a convex portion at a peripheral edge. A phosphor layer is formed inside the frame,
The radiation image conversion panel is characterized in that a protective layer is bonded to at least the projections to shield the phosphor layer from an external atmosphere and to keep the phosphor layer airtight.

Further, according to the present invention, while the radiation image conversion panel in which the radiation image information is stored is moved in the plane direction, the panel is irradiated with excitation light linearly in a direction different from the moving direction. Then, the stimulated emission light emitted from the excitation light irradiation portion of the panel is one-dimensionally received and photoelectrically converted using a line sensor in which a number of solid-state photoelectric conversion elements are linearly arranged, There is also a radiation image information reading method that sequentially reads the output from the line sensor according to the movement of the panel and obtains radiation image information as an electric image signal.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the radiation image storage panel of the present invention will be described below. (1) A radiation image conversion panel whose support is made of quartz or metal. (2) A radiation image conversion panel in which the protective layer is made of glass. (3) A radiation image conversion panel in which the phosphor layer is made of a stimulable phosphor.

The configuration of the radiation image conversion panel of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing an example of the configuration of the radiation image conversion panel of the present invention.

In FIG. 1, a radiation image conversion panel 10
Is composed of a support 1, a phosphor layer 2, and a protective layer 3 in this order from the bottom. The support 1 has a protrusion (frame) on its peripheral edge.
4, and the protective layer 3 is provided on the phosphor layer 2 and the protrusions 4 in close contact with each other. Therefore, the phosphor layer 2 is sealed between the support 1 and the protective layer 3 and is shielded from an external atmosphere.

FIG. 2A is a schematic top view showing a support according to the present invention, and FIG. 2B is a sectional view taken on line II of FIG.
It is sectional drawing along the line. In (1) and (2) of FIG. 2, a convex portion (frame) 4 having a constant width and height is provided on a peripheral portion of the support 1. Width a, c, d, f of frame 4
Are the moisture resistance required for the radiation image conversion panel,
It depends on the rigidity, the conveyance method at the time of reading, the frame material, etc., but is generally in the range of 1 to 100 mm, preferably in the range of 10 to 30 mm. The length of the horizontal b and the vertical e inside the support 1 is determined by the image area required for the panel. However, in practice, an area larger than the image area is required. This is the above (for example, 1.2 times). Therefore, the lengths of the horizontal b and the vertical e are generally in the range of 10 to 100 cm.
The height g of the frame 4 is determined by the radiation absorptivity of the phosphor layer since it corresponds to the thickness of the phosphor layer.
000 μm, preferably 200 μm to 70 μm.
It is in the range of 0 mm. The thickness h of the central portion of the support is determined by the rigidity, moisture resistance and support material required for the panel, but is generally in the range of 0.1 to 10 mm, preferably in the range of 0.5 to 5 mm. is there.

Next, the method for producing the radiation image storage panel of the present invention will be described in detail by taking as an example a case where a phosphor layer comprising a stimulable phosphor is provided. The material of the support having the frame shape as described above can be arbitrarily selected from the materials known as the support of the conventional radiation image conversion panel, but when forming the phosphor layer by the vapor deposition method. It is preferable to use a metal such as quartz or aluminum or a ceramic in consideration of the substrate and the moisture resistance. The frame portion of the support may be formed of a material different from the material of the support, but is preferably made of the same material in terms of strength and moisture resistance. The support may be integrally formed from the beginning by molding the above material, or after the above material is processed into a sheet, a frame portion is attached thereto, provided by vapor deposition, coating, or the like. Is also good. When irradiating secondary excitation light from the support side or detecting stimulated emission light, the support material is preferably a material that transmits each light (for example, quartz glass).

In a known radiation image conversion panel, in order to improve the sensitivity or image quality (sharpness, granularity) of the panel, a light reflecting layer made of a light reflecting material such as titanium dioxide, or a light reflecting material such as carbon black. It is known to provide a light absorbing layer or the like made of an absorbing substance. Also for the support used in the present invention, these various layers can be provided inside the frame, and the configuration thereof can be arbitrarily selected according to the purpose, use, etc. of the desired radiation image conversion panel. . Further, JP-A-58-200
As described in JP-A-200, for the purpose of improving the sharpness of the obtained image, the inner surface of the frame of the support (an undercoat layer (adhesion-imparting layer) on the inner surface of the frame, a light reflecting layer or a light absorbing layer) When an auxiliary layer such as a layer is provided, the surface of the auxiliary layer may be provided).

A phosphor layer is provided in the frame of the support by a vapor deposition method. As a stimulable phosphor, the wavelength is 4
Irradiation of excitation light in the range of 00 to 900 nm results in 300
A stimulable phosphor that emits stimulable light in the wavelength range of from 500 nm to 500 nm is preferred. An example of such a stimulable phosphor is described in
No. 84588, JP-A-2-193100 and JP-A-4-310900.

[0022] Among these, the basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zA ‥‥ alkali metal halide stimulable phosphor represented by (I) Is particularly preferred, provided that M ^I is Li, Na, K, Rb
And represents at least one alkali metal selected from the group consisting of Cs, M ^II is Be, Mg, Ca, Sr, B
a, at least one kind of alkaline earth metal or divalent metal selected from the group consisting of Ni, Cu, Zn and Cd, and M ^III is Sc, Y, La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
m represents at least one rare earth element or trivalent metal selected from the group consisting of Lu, Al, Ga and In, and A represents Y, Ce, Pr, Nd, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu, N
a, at least one rare earth element or metal selected from the group consisting of Mg, Cu, Ag, Tl and Bi.
X, X ′ and X ″ are F, Cl, Br and I, respectively.
Represents at least one halogen selected from the group consisting of a, b and z are respectively 0 ≦ a <0.5, 0 ≦
b <0.5, 0 ≦ z <0.2.

It is preferable that M ^I in the above basic composition formula (I) contains at least Cs. It is preferable that X contains at least Br. A is particularly preferably Eu or Bi. In addition, the basic composition formula (I) includes, if necessary, aluminum oxide,
A metal oxide such as silicon dioxide or zirconium oxide may be added as an additive in an amount of 0.5 mol or less based on 1 mol of M ^I.

Further, a rare earth-activated alkaline earth metal fluorinated halide stimulable phosphor represented by the basic composition formula (II): M ^II FX: zLn ‥‥ (II) is also preferable. However, M ^II is Ba,
Ln represents at least one kind of alkaline earth metal selected from the group consisting of Sr and Ca, and Ln represents Ce, Pr, Sm, E
represents at least one rare earth element selected from the group consisting of u, Tb, Dy, Ho, Nd, Er, Tm and Yb. X represents at least one halogen selected from the group consisting of Cl, Br and I. z is 0 <z ≦ 0.2
Represents a numerical value within the range.

In the above basic composition formula (II), M ^II represents
Ba preferably accounts for more than half. Ln is particularly preferably Eu or Ce. In addition, in the basic composition formula (II), F: X = 1: 1 appears in the notation, which indicates that it has a BaFX type crystal structure, and the stoichiometry of the final composition It does not indicate the composition. In general, a state in which many F ⁺ (X ⁻ ) centers, which are vacancies of X ⁻ ions, are generated in the BaFX crystal is preferable from the viewpoint of increasing the photostimulation efficiency with respect to light of 600 to 700 nm. At this time, F is often slightly more than X.

Although omitted in the basic composition formula (II), one or more of the following additives may be added to the basic composition formula (II) as necessary. bA, wN ^I , xN ^II , yN ^III where A represents a metal oxide such as Al ₂ O ₃ , SiO ₂ and ZrO ₂ . In preventing sintering between M ^II FX particles, it is preferable to use an average particle size of the primary particles has low reactivity with M ^II FX in the following ultrafine particles 0.1 [mu] m. N ^I represents at least one kind of alkali metal compound selected from the group consisting of Li, Na, K, Rb and Cs; N ^II represents an alkaline earth metal compound consisting of Mg and / or Be; ^III is Al, Ga, In,
It represents a compound of at least one trivalent metal selected from the group consisting of Tl, Sc, Y, La, Gd and Lu. As these metal compounds, it is preferable to use halides as described in JP-A-59-75200, but it is not limited thereto.

B, w, x and y are each M ^II
This is the charged addition amount when the number of moles of FX is 1, and 0
≦ b ≦ 0.5, 0 ≦ w ≦ 2, 0 ≦ x ≦ 0.3, 0 ≦ y ≦
Represents a numerical value within each range of 0.3. These figures do not represent the element ratios contained in the final composition for additives that are reduced by baking or subsequent cleaning. Some of the above compounds may remain as added in the final composition.
^Some react with ^II FX or are incorporated.

In addition, if necessary, the basic composition formula (II) may further include, as necessary, Z Z described in JP-A-55-12145.
n and Cd compounds; TiO ₂ , BeO, MgO, C which are metal oxides described in JP-A-55-160078.
aO, SrO, BaO, ZnO, Y 2 O 3, La 2 O 3, I
n ₂ O ₃ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Th
O ₂ ; Zr and Sc compounds described in JP-A-56-116777; B compounds described in JP-A-57-23673; As described in JP-A-57-23675.
And Si compounds; tetrafluoroboric acid compounds described in JP-A-59-27980; JP-A-59-4728.
No. 9, hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid, a hexafluoro compound comprising a monovalent or divalent salt of hexafluorozirconic acid; V, Cr, Mn, F
e, a compound of a transition metal such as Co and Ni, or the like may be added. Further, the present invention is not limited to the phosphor containing the above-described additive, and any phosphor having a composition which is basically regarded as a rare earth activated alkaline earth metal fluorinated halide-based stimulable phosphor can be used. It may be.

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

In the present invention, the phosphor layer can be formed on a support by, for example, an electron beam evaporation method, which is a kind of vapor deposition method, as follows. In the electron beam evaporation method, a columnar crystal having a good shape and a well-aligned array is obtained, and at the same time, the evaporation source is locally heated and evaporated instantaneously. After evaporation (for example, the activator evaporates before the phosphor matrix), the composition of the phosphor charged as the evaporation source does not match the composition of the phosphor in the formed phosphor layer. There is almost nothing.

First, a stimulable phosphor as an evaporation source and a substrate as an object to be deposited are placed in a deposition apparatus, and the inside of the apparatus is evacuated to about 3 × 10 ^{−7 to} 3 × 10 ⁻⁴ Pa. Degree of vacuum. At this time, while maintaining the degree of vacuum at this level, Ar
An inert gas such as a gas or a Ne gas may be introduced.

It is preferable that the stimulable phosphor is processed into a tablet (pellet) shape by pressure compression. The compression under pressure is generally performed by applying a pressure in the range of 800 to 1000 kg / cm ² . During compression, the tablet may be heated to a temperature in the range of 50 to 200 ° C., and after compression, the resulting tablet may be subjected to a degassing treatment. Thereby, the relative density of the evaporation source can be increased. If the relative density of the evaporation source is low,
If the phosphor does not evaporate uniformly, the film thickness of the deposited film becomes uneven, bumps adhere to the substrate, and the phosphor itself evaporates unevenly, and the phosphor is activated in the deposited film. Agents and additives may segregate. Further, it is also possible to use the raw material or the raw material mixture instead of the stimulable phosphor.

Next, an electron beam is generated from the electron gun and irradiated to the evaporation source. At this time, the electron beam acceleration voltage is set to 1.5
It is desirable to set the voltage to not less than kV and not more than 5.0 kV. If the acceleration voltage is lower than 1.5 kV, the voltage becomes unstable, the beam position of the electron beam fluctuates, or the shape of the scanning surface by the electron beam of the evaporation source changes to keep the evaporation surface flat. It becomes difficult. On the other hand, when the acceleration voltage is higher than 5.0 kV, the columnar crystals of the phosphor that grows in vapor phase by evaporation become uneven.

The stimulable phosphor, which is an evaporation source, is heated by the irradiation of the electron beam, evaporates and scatters, and deposits on the substrate surface. The deposition rate of the phosphor, that is, the deposition rate, is generally in the range of 0.1 to 1000 μm / min, preferably in the range of 1 to 100 μm / min. The irradiation of the electron beam may be performed a plurality of times to form two or more phosphor layers, or different phosphors may be co-evaporated using a plurality of electron guns. Further, it is also possible to synthesize a phosphor on a substrate using the phosphor raw material and simultaneously form the phosphor layer. Further, the object to be deposited (substrate) may be cooled or heated as necessary during the vapor deposition, or the phosphor layer may be subjected to a heat treatment (annealing treatment) after the vapor deposition.

The vapor phase deposition method used in the present invention is not limited to the above-mentioned electron gland deposition method, but employs other deposition methods such as a resistance heating method or various known methods such as a sputtering method. be able to.

In this manner, a phosphor layer in which the columnar crystals of the stimulable phosphor have grown substantially in the thickness direction is obtained. The phosphor layer does not contain a binder and consists only of a stimulable phosphor,
Voids (cracks) exist between the columnar crystals of the stimulable phosphor. The thickness of the phosphor layer is usually 50 to 1
000 μm, preferably 200 μm to 70 μm.
It is in the range of 0 mm. Note that the phosphor layer does not necessarily need to be formed by vapor phase growth of the phosphor directly on the support as described above. For example, the phosphor layer may be separately formed on a substrate such as a glass plate, a metal plate, or a plastic sheet. After the phosphor layer is formed by vapor-phase growth, a method of bonding the phosphor layer on a support using an adhesive or the like may be used, or the phosphor layer may be formed on a protective layer. .

On the support having the phosphor layer, a protective layer is provided. The protective layer can be arbitrarily selected from known materials as a protective layer of a conventional radiation image conversion panel, but it is preferable to use a transparent inorganic film, particularly transparent glass or ceramic in consideration of moisture resistance. The protective layer can be formed by depositing such a material on the frame of the phosphor layer and the support. Alternatively, a sheet made of such a material is placed on the upper frame of the support,
Further, it can be provided by adhering on the phosphor layer using an appropriate adhesive. In the protective layer, various additives such as light scattering fine particles such as magnesium oxide, zinc oxide, titanium dioxide, and alumina, slip agents such as perfluoroolefin resin powder and silicone resin powder, and cross-linking agents such as polyisocyanate. May be dispersedly contained. The thickness of the protective layer is preferably thin in order to prevent blurring of the radiation image, but too thin is not preferred because the moisture permeability increases. Generally, the thickness of the protective layer is 100 to 100
0 μm, preferably 200 μm to 500 μm
m. Thus, the protective layer can be provided on the phosphor layer, and at the same time, the phosphor layer can be sealed by the support and the protective layer, thereby shielding the phosphor layer from the external atmosphere.

A fluorine resin coating layer may be further provided on the surface of the protective layer in order to increase the stain resistance of the protective layer. The fluororesin coating layer can be formed by applying a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent on the surface of the protective layer and drying.
The fluororesin may be used alone, but is usually used as a mixture of the fluororesin and a resin having a high film forming property. Further, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used in combination. The fluororesin coating layer may be filled with a particulate filler in order to reduce interference unevenness and further improve the quality of a radiographic image. The thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, additional components such as a crosslinking agent, a hardening agent, an anti-yellowing agent and the like can be used. In particular, the addition of a crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

Although the radiation image conversion panel of the present invention is obtained as described above, the configuration of the panel of the present invention may include various known variations. For example, for the purpose of improving the sharpness of the obtained image, at least one of the above-mentioned layers may be colored with a coloring agent that absorbs excitation light but does not absorb stimulating light (Japanese Patent Publication No. No. 59-23400).

Next, the radiation image information reading method of the present invention using the above radiation image conversion panel will be described with reference to the drawings.

FIG. 3 is a configuration diagram showing an example of a radiation image information reading apparatus used in the method of the present invention, and FIG. 4 is a cross-sectional view taken along line II of FIG. 3, the radiation image conversion panel 10 has a structure including a support 1, a phosphor layer 2 made of a stimulable phosphor, and a protective film 3 as shown in FIG. Radiation image information of the subject is accumulated and recorded, for example, by irradiation with radiation. The radiation image conversion panel 10 placed on the scanning belt 40 is conveyed in the arrow Y direction as the scanning belt 40 moves in the arrow Y direction. The conveying speed of the panel 10 is equal to the moving speed of the belt 40, and the moving speed of the belt 40 is input to the image reading means 30.

On the other hand, a broad area laser (hereinafter referred to as BL
D), a linear excitation light L emitted substantially parallel to the surface of the panel 10 is converted into a parallel beam by an optical system 12 including a collimator lens and a toric lens provided on the optical path, 45 for panel 10
The dichroic mirror 14 is arranged to be inclined at an angle of degree, and is set to reflect the excitation light and transmit the stimulating light. Gradient index lens array (a lens in which a number of gradient index lenses are arranged, hereinafter referred to as a first selfoc lens array) 1
5, the light is condensed on the panel 10 in a linear shape extending along the arrow X direction.

Excitation of the linear excitation light L incident on the panel 10 causes the stimulated emission light M having an intensity corresponding to the accumulated and recorded radiation image information to be emitted from the condensing area of the panel 10 and its vicinity. . The stimulated emission light M is converted into a parallel light beam by the first selfoc lens array 15, passes through the dichroic mirror 14, and is converted by the second selfoc lens array 16 into each photoelectric conversion element 21 constituting the line sensor 20. Is collected on the light receiving surface of the. The line sensor 20 has a large number of solid-state photoelectric conversion elements 21 arranged at least along the length of the linear excitation light irradiation portion, and each element corresponds to one pixel.

Here, considering the resolving power of the line sensor, the allowable range of the position of the light receiving surface (which is called "depth of focus") at which a clear image can be obtained is small. It is required to keep the distance between them constant. In the past, the distance between the panel and the line sensor was adjusted to be constant by using a protective layer surface further provided by bonding or the like on the vapor-phase deposited phosphor layer as a reference on the panel side. In the present invention, since the surface of the protective layer on the frame of the support that has been accurately prepared in advance can be used as a reference, it is easy to keep the distance constant.

At this time, the excitation light L slightly reflected in the stimulated emission light M transmitted through the second selfoc lens array 16 and reflected on the surface of the panel 10 cuts the excitation light to generate the stimulated emission light. It is cut by the transmitted excitation light cut filter 17.

The stimulated emission light M received by each photoelectric conversion element 21 is photoelectrically converted, and each signal S obtained by the photoelectric conversion is input to the image information reading means 30. Each signal S is processed by the image information reading means 30 in accordance with the position of the panel 10 based on the moving speed of the scanning belt 40, and is output as image data to an image processing device (not shown).

The radiation image information reading apparatus used in the present invention is not limited to the embodiments shown in FIGS. 3 and 4, but includes a light source, a condensing optical system between the light source and the panel, a panel and a line sensor. Various known configurations can be employed for the optical system and the line sensor. For example, as the line light source, the light source itself may be linear, and a fluorescent lamp, a cold cathode fluorescent lamp, an LED (light emitting diode) array, an LD (semiconductor laser) array, or the like can also be used. The excitation light emitted from the line light source may be one that emits continuously, or may be pulse light that repeats emission and stop. From the viewpoint of noise reduction, it is preferable that the light is a high-output pulse light.

As the line sensor, an amorphous silicon sensor, a CCD sensor, a CCD with a back illuminator, a MOS image sensor, or the like can be used.

The direction in which the radiation image conversion panel is moved is
It is desirable that the direction is substantially perpendicular to the length direction of the line light source and the line sensor, but, for example, within a range where the excitation light can be uniformly irradiated over substantially the entire surface of the panel,
It may be moved in an oblique direction deviating from the length direction or in a zigzag manner.

In the above embodiment, the optical system between the panel 10 and the line sensor 20 is set to a 1: 1 image forming system for the sake of simplicity. Is also good. However, it is preferable to use a unity or magnifying optical system in order to increase the light collection efficiency. In the above-described embodiment, the device is made compact by adopting a configuration in which the optical path of the excitation light L and the optical path of the photostimulated light M partially overlap. A completely different optical path may be adopted. Alternatively, the image processing apparatus may further include an image processing device that performs various signal processing on the data signal output from the image information reading unit, or may appropriately emit radiation energy still remaining on the panel after the reading is completed. A configuration further including an erasing means may be employed.

[0051]

EXAMPLES Example 1 (1) Preparation of evaporation source 100 g of cesium bromide (CsBr, 0.47 mol) and 1.8404 g of europium bromide (EuBr ₃ , 4.7 ×)
10 ⁻³ mol) in a mortar, and then mixed by stirring with a stirring vibrator for 15 minutes. The resulting mixture was placed in a furnace, evacuated for 3 minutes, and then heated to 525 ° C. in a nitrogen atmosphere.
For 2 hours. After firing, the furnace was evacuated for 15 minutes to cool the fired product. Then, the obtained europium-activated cesium bromide (CsBr: 0.01 Eu) stimulable phosphor was pulverized in a mortar, and then press-compressed at a pressure of 800 kg / cm ² to prepare a tablet for vapor deposition. Tablets with an additional temperature of 15
Evacuation was performed at 0 ° C. for 2 hours to perform a degassing treatment.

(2) Formation of Phosphor Layer An integrated quartz frame (frame width a, c, d, f: 20 mm, frame height g: 5) as shown in FIG. 2 was used as a support.
00 μm, the area in the frame b × e: 40 cm × 40 cm, and the thickness h: 10 mm). After placing the support and the evaporation source at predetermined positions in the vapor deposition apparatus, the inside of the apparatus was evacuated to a degree of vacuum of 3.0 × 10 ⁻⁶ Pa. Then, an electron gun was irradiated with an electron beam having an acceleration voltage of 4.0 kV and 60 W using an electron gun to deposit a stimulable phosphor at a rate of 25 μm / min in the frame of the support. Thereafter, the irradiation of the electron beam was stopped, the inside of the apparatus was returned to the atmospheric pressure, and the support was taken out of the apparatus. On the support, a vapor-deposited film (film thickness: 480 μm) having a structure in which columnar crystals of a phosphor having a width of about 10 μm and a length of about 480 μm were densely formed almost vertically in a vertical direction was formed.

(3) Formation of Protective Layer A glass material is vapor-deposited on the above-mentioned phosphor layer and the frame of the support to form a protective layer (thickness: 50 μm), and at the same time the phosphor layer is sealed. The support and the protective layer were bonded. Thus, a radiation image conversion panel of the present invention comprising the support, the phosphor layer and the protective layer was obtained (see FIG. 1).

Comparative Example 1 In Example 1, a quartz sheet (thickness: 10 mm) was used as a support, a protective layer (layer thickness: 50 μm) was used, a silicon dioxide (SiO ₂ ) phosphor layer and a support were used. A radiation image conversion panel as shown in FIG. 5 was manufactured in the same manner as in Example 1 except that the radiation image conversion panel was formed by vapor deposition on the above.

FIG. 5 is a schematic sectional view showing the configuration of the radiation image conversion panel of Comparative Example 1. In FIG. 5, the radiation image conversion panel includes a support 51 and a phosphor layer 5 in this order from the bottom.
2 and a protective layer 53. The protective layer 53 is joined to the support body 51 at the periphery thereof so as to cover the phosphor layer, and the phosphor layer 52 is sealed between the support body 51 and the protective layer 53.

Comparative Example 2 A quartz sheet (thickness: 10 mm) was used as a support, and a phosphor layer was formed thereon in the same manner as in Example 1. Next, a glass spacer (width: 20 mm) having the same height as the thickness of the phosphor layer is disposed on the support and around the phosphor layer, and then a polyethylene terephthalate sheet (thickness: 50 μm) is placed. Was bonded to a phosphor layer and a spacer using an adhesive to form a protective layer. Thus, a radiation image conversion panel as shown in FIG. 6 was manufactured.

FIG. 6 is a schematic sectional view showing the configuration of the radiation image conversion panel of Comparative Example 2. In FIG. 6, the radiation image conversion panel includes a support 61 and a phosphor layer 6 in this order from the bottom.
2 and a protective layer 63. A spacer 6 is provided between the support 61 and the protective layer 63 along the periphery thereof.
5 are arranged and joined, and the phosphor layer 62 is sealed in a space formed by the support 61, the protective layer 63, and the spacer 65.

Comparative Example 3 In Comparative Example 2, instead of bonding a polyethylene terephthalate sheet, silicon dioxide (SiO ₂ ) was vapor-deposited on the phosphor layer and the spacer to form a protective layer (layer thickness: 50 μm). Except for this, a radiation image conversion panel as shown in FIG. 6 was manufactured in the same manner as in Comparative Example 2.

[Evaluation of Performance of Radiation Image Conversion Panel] Each of the obtained radiation image conversion panels was subjected to a moisture resistance test to evaluate its performance.

The radiation image conversion panel was operated at 40 ° C. and 80% RH.
After one week of standing in a high-temperature, high-humidity room, the change in the amount of stimulated emission from the panel before and after the standing was measured and evaluated according to the following criteria. A: A decrease in luminescence of less than 5%. B: A decrease in luminescence of 5% or more and less than 10%. C: A decrease in luminescence of 10% or more. Table 1 summarizes the obtained results.

[0061]

[Table 1] Table 1 湿 Moisture resistance ──────────────────── ── Example 1 A 比較 Comparative Example 1 B Comparative Example 2 C Comparative Example 3 D ────────── ────────────

As is clear from the results shown in Table 1, the radiation image conversion panel of the present invention (Example 1) has a higher moisture resistance than the various known radiation image conversion panels (Comparative Examples 1 to 3). Was significantly better. It is considered that Comparative Example 1 exhibited insufficient moisture resistance because the adhesion of the SiO ₂ protective layer was not so good. It is considered that Comparative Examples 2 and 3 exhibited insufficient moisture resistance because the adhesion between the spacer and the support was not perfect. Further, compared with Example 1, Comparative Examples 2 and 3 require a step of separately providing a spacer, and the manufacturing steps are complicated.

[0063]

According to the present invention, the use of the frame as the support eliminates the need for spacers, simplifies the structure of the radiation image conversion panel, and significantly improves the moisture resistance. At the same time, the manufacturing process can be simplified. When a protective layer is provided on the upper and side surfaces of the phosphor layer by a vapor deposition method without a spacer, it is necessary to form the protective layer with a thickness sufficient to completely contain the phosphor layer. There was a problem that it was easily blurred,
Such a problem does not occur in the present invention.

Further, when the radiation image conversion panel of the present invention is used in a radiation image information reading method using a line sensor, the distance between the panel and the line sensor is adjusted by utilizing the upper frame of the support. It is easy to keep the distance constant, and a higher quality radiation image can be obtained by increasing the clearance of the line sensor. Therefore, the radiation image conversion panel and the reading method of the present invention
It is advantageous when used for medical diagnostic radiography, industrial radiography, and fluoroscopy.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of the configuration of a radiation image conversion panel of the present invention.

FIG. 2A is a schematic top view showing a support according to the present invention, and FIG. 2B is a cross-sectional view taken along line II of FIG.

FIG. 3 is a configuration diagram illustrating an example of a radiation image information reading apparatus used in the method of the present invention.

FIG. 4 is a sectional view of the radiation image information reading apparatus shown in FIG.
It is sectional drawing along the line.

FIG. 5 is a schematic sectional view showing an example of the configuration of a radiation image conversion panel of Comparative Example 1.

FIG. 6 is a schematic cross-sectional view showing another example of the configuration of the radiation image conversion panels of Comparative Examples 2 and 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Support 2 Phosphor layer 3 Protective layer 4 Convex part (frame) 10 Radiation image conversion panel 11 Broad area laser (BLD) 12 Optical system consisting of a collimator lens and a toric lens 14 Dichroic mirror 15, 16 Selfoc lens array 17 Excitation Light cut filter 20 Line sensor 21 Solid-state photoelectric conversion element 30 Image information reading means 40 Scanning belt L Excitation light M Stimulated emission light S Signal

Claims (7)

[Claims] 1. A radiation image conversion panel having a support, a phosphor layer formed by a vapor deposition method, and a protective layer in this order, wherein the support has a shape of a frame having a convex portion at a peripheral portion. A radiation image conversion device, wherein a phosphor layer is formed inside the frame, and a protective layer is bonded to at least the projections to shield the phosphor layer from an external atmosphere to be in an airtight state. panel. 2. The radiation image storage panel according to claim 1, wherein the support is made of quartz or metal. 3. The radiation image storage panel according to claim 1, wherein the protective layer is made of glass. 4. The radiation image conversion panel according to claim 1, wherein the phosphor layer is made of a stimulable phosphor. 5. The radiation image conversion panel according to claim 1, wherein the radiation image conversion panel on which the radiation image information is stored is moved in a plane direction thereof. A line formed by linearly irradiating the panel with excitation light in a direction different from the moving direction, and stimulating light emitted from an excitation light-irradiated portion of the panel to a large number of solid-state photoelectric conversion elements arranged linearly. A radiation image obtained by one-dimensionally receiving light using a sensor, performing photoelectric conversion, and sequentially reading the output from the line sensor according to the movement of the panel to obtain radiation image information as an electric image signal Information reading method. 6. A method for adjusting the distance between the panel and the line sensor based on a position on the surface of the radiation image conversion panel, the position corresponding to the protrusions on both sides of the support parallel to the moving direction of the panel. The radiation image information reading method according to claim 5, wherein: 7. The radiation image information reading method according to claim 5, wherein an area of the phosphor layer of the radiation image conversion panel is larger than an image area.