JPH08114897A - Intensifying screen for dry process x-ray film - Google Patents

Abstract

PURPOSE: To make it possible to rapidly obtain a transmissive film with high accuracy even to an object which is to be inspected and has a high transmission thickness by providing the surface of a base with a scattering preventive layer consisting of lead foil and a phosphor layer formed by dispersing rare earth phosphors into a binder thereon. CONSTITUTION: The surface of the base 1 is provided with the scattering preventive layer 2 consisting of the lead foil and the phosphor layer 3 formed by dispersing the rare earth phosphors into the binder thereon. The scattering preventive layer 2 is a layer for preventing the forward and backward scattering of the X-rays at the time of using sensitizing paper and the lead foil is directly adhered on the base 1 in order to form the scattering preventive layer 2. The phosphor layer 3 is a layer for enhancing the sensitivity of an X-ray film. The phosphor layer 3 is formed simply by applying a dispersion prepd. by dispersing the rare earth phosphors into an org. solvent soln. of the binder on the scattering preventive layer 2 formed on the base 1 and drying the coating. The sensitizing paper is composed of such double laminated structure and the phosphor layer 3 is further preferably provided thereon with a transparent protective layer 4 in order to protect the phosphor layer 3 on the surface against chemical change in properties and physical impact.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an intensifying screen used for sensitizing a dry X-ray film in an X-ray transmission test.

[0002]

2. Description of the Related Art In an X-ray transmission test for various industrial X-ray photography such as medical diagnosis and non-destructive inspection of substances, X-ray transmission
The intensifying screen is adhered to one or both sides of the line film to take a picture.

Conventionally used intensifying screens are of a single-layer structure in which a rare earth-based phosphor layer is provided on a support (hereinafter referred to as a rare earth fluorescent intensifying screen) and a support. It is roughly classified into a laminated structure type (hereinafter referred to as a metal fluorescent intensifying screen) in which an X-ray scattering prevention layer made of a metal foil such as lead foil and a non-rare earth phosphor layer such as calcium tungstate are sequentially provided. It The former rare earth fluorescent intensifying screen is used only for medical diagnosis as a wet X-ray film using a liquid developer for developing the X-ray film.

[0004]

Since the rare earth fluorescent intensifying screen has high sensitivity, it is possible to obtain a transmission photograph with a small X-ray dose, but it is not possible to obtain a highly accurate X-ray transmission photograph. On the other hand, the metal fluorescent intensifying screen can obtain a high-accuracy transmission photograph, but since the sensitivity is low, in order to obtain a transmission photograph of the inspection object having a large transmission thickness, the irradiation time required for photographing becomes long, It lacks promptness.

As described above, conventionally, there is no high-sensitivity and high-precision dry X-ray film intensifying screen, and for an inspection object having a large transmission thickness, either speediness or precision must be sacrificed. I had to do it. Incidentally, the dry X-ray film is different from the wet X-ray film which is developed by a complicated wet development method including development-stop-fixing-washing-washing steps, and in particular, only a heating step (for example, heating at 133 ° C for 6 seconds) is performed. It was developed as an X-ray film that has the feature that it can be developed by a simple heat development method and can immediately respond to various nondestructive inspections.

An object of the present invention is to provide a high-sensitivity intensifying screen for a dry X-ray film, which can quickly obtain a highly accurate transmission photograph even for an inspection object having a large transmission thickness.

[0007]

The present invention adopts the following means in order to solve the above problems. That is, the intensifying screen of the present invention comprises a support, on which a scatter-preventing layer made of lead foil and a phosphor layer in which a rare earth phosphor is dispersed in a binder are provided. Used in combination with film.

The intensifying screen of the present invention will be described in detail below with reference to FIG. 1 is a block diagram of an intensifying screen of an example of the present invention, in which 1 is a support, 2 is an anti-scattering layer, 3 is a phosphor layer, and 4 is a transparent protective layer. <Anti-scattering layer 2> The anti-scattering layer 2 is X when the intensifying screen is used.
A layer to prevent the forward and backscattering of lines, which is composed of lead foil. The thickness of this layer is preferably about 10 to 500 μm, and particularly preferably about 20 to 50 μm. To form the anti-scatter layer, lead foil is directly adhered to the support. <Phosphor layer 3> The phosphor layer 3 is a layer for increasing the sensitivity of the X-ray film, and is a rare earth phosphor dispersed in a binder. The thickness of this layer is preferably about 70 to 200 μm, particularly preferably about 100 to 150 μm. This phosphor layer is
Whether the X-ray film is an ortho type (type having sensitivity to green) or a regular type (type having sensitivity to blue) by appropriately selecting the type of rare earth phosphor as described below. It shows a remarkable sensitizing effect.

In order to form such a phosphor layer 3, a dispersion liquid in which a rare earth phosphor is dispersed in an organic solvent solution of a binder is applied and dried on the anti-scattering layer 2 provided on a support. do it. It should be noted that a plasticizer may be added to this dispersion to improve the binding force between the phosphor and the binder, or a dispersant may be added to improve the dispersibility of the phosphor.

[0010] As the rare-earth phosphor used in the phosphor layer, the general formula I M _(wn) such as those described in ^{_{JP-A-48-81582 O w X: M 1 n}} ( where, M is yttrium (Y ), Lantern (La),
It represents at least one selected from the group consisting of gadolinium (Gd) and lutetium (Lu), and M ¹ is dysprosium (Dy), erbium (Er), europium (Eu), holmium (Ho), neodymium (Nd), Protheodymium (Pr), samarium (Sm), terbium (Tb), thulium (Tm) and ytterbium (Y
b) represents at least one selected from the group consisting of
Represents sulfur or halogen, and n is 0.0002 to 0.2.
And w is 1 when X is halogen and 2 when X is sulfur. ), Preferably represented by the general formula II Ln ₂ O ₂ S: Tb described in JP-B-4-75479 (where Ln is at least 1 of Y, La, Gd and Lu).
Species, preferably at least one of Y, La and Gd. ), A terbium-activated rare earth oxysulfide, for example, terbium-activated gadolinium oxysulfide (Gd ₂ O ₂ S: Tb), terbium-activated yttrium oxysulfide (Y ₂ O ₂ S: Tb), terbium-activated lanthanum oxysulfide (La ₂ O). ₂ S: T
b), terbium activated gadolinium / yttrium oxysulfide [(Gd, Y) ₂ O ₂ S: Tb] and the like. Note that Ce, Tm, Er, Pr or the like may be added to the phosphor of the general formula II as a coactivator of Tb.

In the phosphor represented by the above composition formula, when the rare earth which is the constituent component of the matrix is, for example, yttrium, light is emitted mainly in the blue region, but when the rare earth is lanthanum, gadolinium or lutetium, it is mainly emitted. Light emission is shown in the green region. In addition, the luminescent color differs depending on the activation amount of terbium, which is an activator, and as the amount of terbium increases, the emission in the green region tends to be emphasized. Therefore, for example, when the phosphor of the above composition formula is used, the emission color of the intensifying screen is changed by changing the kind and composition ratio of the rare earth element which is the constituent component of the matrix, or the amount of terbium which is the activator. It can be changed in the range from blue to green.

On the other hand, as a binder for forming a phosphor layer together with the above-mentioned phosphor, proteins such as gelatin, polysaccharides such as dextran, gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride to chloride are used. Vinyl copolymer, polymethylmethacrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate butyrate,
Examples include polyvinyl alcohol, linear polyester, and natural or synthetic polymer substances such as a mixture thereof. Among them, nitrocellulose, polyvinyl butyral, and vinyl chloride are excellent because they have excellent flexural strength or flexibility as a film. Vinyl acetate copolymer is preferred.

The mixing ratio of the phosphor and the binder in the phosphor layer varies depending on the characteristics of the target intensifying screen, the type of phosphor, etc., but is generally (1 to 100): 1 (weight ratio). ),
The range is preferably (8-40): 1. <Support 1> Anti-scattering layer 2 and phosphor layer 3 as described above
Examples of the support 1 for supporting: a plastic film such as a polyethylene terephthalate film, a cellulose acetate film, a polyamide film, a polyimide film, a triacetate film, a polycarbonate film; a metal foil such as an aluminum foil or an aluminum alloy foil; a plain paper; Baryta paper, resin coated paper,
Pigment paper containing pigments such as titanium dioxide, papers such as sizing paper sized with polyvinyl alcohol and the like, and composites thereof are mentioned. Among them, plastic film is excellent in bending strength or flexibility. Polyethylene terephthalate is particularly preferable. The plastic film may contain a light absorbing substance such as carbon black or a light reflecting substance such as titanium dioxide.

The thickness of the support varies depending on its type, but in the case of a plastic film, it is 100 to 30.
A range of about 0 μm, particularly about 150 to 200 μm is preferable. <Transparent Protective Layer 4> The intensifying screen of the present invention has a double-layered structure as described above. However, in order to protect the surface phosphor layer from chemical alteration and physical impact, it is formed on the phosphor layer. Further, it is preferable to provide a transparent protective layer. Examples of the material for forming the protective layer include cellulose derivatives (eg, cellulose acetate, nitrocellulose), polymethylmethacrylate,
Examples thereof include polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyethylene terephthalate, polyethylene, polyvinylidene chloride, and polyamide.
These are dissolved in an appropriate organic solvent to form a solution, which is applied on the phosphor layer or formed into a film in advance,
A protective layer can be formed by bonding this to the phosphor layer with an appropriate adhesive. The thickness of the protective layer is preferably about 3 to 15 μm. <Method of using the intensifying screen of the present invention> The intensifying screen of the present invention is used by adhering it to one side or both sides of an X-ray film and applying the same to an object to be inspected as in the conventional case. In order to obtain the effect of X-ray film, the X-ray film must be of a type that is dry-processed and heat-developed.

Further, in the industrial non-destructive inspection, since it is often applied to an inspection object having a particularly small curvature, in such a case, it is preferable to use an intensifying screen which is easy to bend and has good flexibility. . As a flexible intensifying screen, a group in which the support is made of a polyethylene terephthalate film having a thickness of 100 to 300 μm and the binder of the phosphor layer is made of nitrocellulose, polyvinyl butyral and vinyl chloride-vinyl acetate copolymer It is preferable that at least one kind selected from the above and the thickness of the phosphor layer is 70 to 200 μm.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to examples.

[0017]

Example 1 An anti-scattering layer 2 made of a lead foil having a thickness of 30 μm (previously coated with a polyester adhesive) was adhered and formed on a polyethylene terephthalate support 1 having a thickness of 188 μm, and terbium activation was performed thereon. Add 95 parts by weight of gadolinium oxysulfide to polyvinyl butyral 5
A dispersion liquid (a solvent is a mixed solvent of ethyl alcohol and toluene) dispersed in parts by weight is uniformly applied with a doctor blade and dried to form a phosphor layer 3 having a thickness of 120 μm. A protective layer 4 was formed by adhering the adhesive surface of a polyethylene terephthalate film having a thickness of 9 μm to which a polyester adhesive was applied in advance to form the intensifying screen of the present invention (hereinafter referred to as intensifying screen D).

On the other hand, as a comparative intensifying screen, a conventional metallic fluorescent intensifying screen (trade name: SMP308 manufactured by Kasei Optonix Co., Ltd.)
(An anti-scattering layer consisting of 30 μm thick lead foil on a 290 μm thick paper support and calcium tungstate 1
A phosphor layer having a thickness of 20 μm and a polyethylene terephthalate layer having a thickness of 9 μm are sequentially provided, which is hereinafter referred to as intensifying screen A. ), Rare earth fluorescent intensifying screen (trade name T manufactured by DuPont)
6) (total thickness 600 μm; a terbium-activated gadolinium oxysulfide Gd ₂ O ₂ S: Tb phosphor layer and a protective layer are sequentially provided on a paper support, which is hereinafter referred to as intensifying screen B), And a rare earth fluorescent intensifying screen (trade name T12 manufactured by DuPont) (total thickness: 720 μm; terbium-activated gadolinium oxysulfide Gd ₂ O ₂ S: Tb on a paper support).
A fluorescent substance layer and a protective layer are sequentially provided, which will be hereinafter referred to as an intensifying screen C. ) Was prepared. X-ray transmission test: Each of the above intensifying screens was brought into close contact with a dry X-ray film (made by DuPont) called a rapid film,
An X-ray transmission test was performed under the following shooting conditions to evaluate the sensitivity of the intensifying screen and the resolution of the transmitted image.

X-ray tube voltage and current: 160 KVp, 3 mA Thickness of inspection object (iron plate): 9 mm FFD: 600 mm Film density: 1.7 to 1.9 <Comparison of sensitivity> A transmission test was performed under the above photographing conditions. The sensitivity at that time was determined as the X-ray irradiation time required for transmission. The result is shown in FIG.

It can be said that the shorter the X-ray irradiation time, the better the sensitivity. From FIG. 2, it was the intensifying screen C that had the highest sensitivity, but the intensifying screen D of the present invention has almost the same sensitivity as the intensifying screen C having the highest sensitivity. On the other hand, the sensitivity of the intensifying screen B was rather low, and the sensitivity of the intensifying screen A was extremely low. <Comparison of Resolutions> The resolution of each transmission image obtained by performing the above-mentioned transmission test was evaluated as the degree of discrimination by a transmission meter.
The result is shown in FIG.

The smaller the numerical value is, the higher the degree of identification (resolution) is, which means that a minute defect can be detected. It can be seen from FIG. 3 that the intensifying screen D of the present invention has the highest degree of distinction together with the intensifying screen A, the intensifying screen B has the next highest degree of discrimination, and the intensifying screen C has the lowest degree of discrimination. According to JIS Z3104, the degree of distinction required for a transmission image is 2.0. Bending test: Each of the above-mentioned intensifying screens was wound around a pipe having a diameter of 50 to 300 mm and the ease of bending was evaluated. As a result, intensifying screen C
Wrinkles occurred at 60 mmφ or less, whereas no wrinkles were observed in other intensifying screens within the above range of curvature. Also, the degree of bending of each intensifying screen due to its own weight was measured. The results are shown in Table 1.

[0022]

[Table 1] From Table 1, intensifying screen D of the present invention is most easily bent, and intensifying screen A
However, next to this, it is understood that the intensifying screens B and C are considerably difficult to bend, and those having a small curvature are difficult to use.

[0023]

According to the intensifying screen of the metal / rare earth phosphor layer structure of the present invention as described above, when applied to a dry X-ray film, the sensitivity (rapidity), accuracy (discrimination), and bending are improved. In terms of sex, it can be greatly improved as compared with the conventional intensifying screen. That is, the degree of discrimination was better than that of the conventional rare earth fluorescent intensifying screen, and the sensitivity was significantly higher than that of the conventional metal fluorescent intensifying screen, which was equivalent to that of the rare earth fluorescent intensifying screen. Further, in particular, when the support and the phosphor layer are made thin and a flexible plastic and resin binder which is resistant to bending is used for the material of the support and the phosphor layer, any conventional intensifying screen is used. Easier to bend than Therefore, the use of such an intensifying screen which is easily bendable is particularly suitable for testing an inspection object having a small curvature.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing the configuration of an example of an intensifying screen of the present invention.

FIG. 2 is a diagram comparing the required irradiation times of the present invention and the conventional intensifying screen tested in Example 1 as sensitivity.

FIG. 3 is a diagram comparing the discriminating degree of the intensifying screen of the present invention and the conventional intensifying screen tested in Example 1 as accuracy.

[Explanation of symbols]

 1 ... Support 2 ... Anti-scattering layer 3 ... Phosphor layer 4 ... Protective layer A, B, C ... Conventional intensifying screen D ... Intensifying screen of the present invention

Claims (2)

[Claims] 1. An anti-scattering layer made of lead foil on a support,
A intensifying screen for a dry X-ray film, which further comprises a phosphor layer in which a rare earth phosphor is dispersed in a binder. 2. The support is made of a polyethylene terephthalate film having a thickness of 100 to 200 μm, and the binder of the phosphor layer is at least one selected from the group consisting of nitrocellulose, polyvinyl butyral and vinyl chloride-vinyl acetate copolymer. And the thickness of the phosphor layer is 70-
The intensifying screen according to claim 1, which has a thickness of 200 μm.