JPH0690317B2 - Radiographic intensifying screen - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a radiographic intensifying screen. More specifically, in the present invention, the composition ratio of the support to the binder and the phosphor provided on the support is 1: 1 to 1:25 (weight ratio, but not including 1:25). The present invention relates to a radiation intensifying screen substantially composed of a phosphor-containing resin layer in the range.

Radiographic intensifying screens are used in radiographic imaging in various fields such as medical radiographic imaging such as X-ray imaging for medical diagnosis and industrial radiographic imaging for nondestructive inspection of substances. In order to improve the sensitivity of (1), it is used by superimposing it on one side or both sides of a radiographic film such as an X-ray photographic film. This radiation intensifying screen has, as a basic structure, a support and a phosphor-containing resin layer formed on one surface thereof. Incidentally, a transparent protective film is generally provided on the surface of the phosphor-containing resin layer opposite to the support (the surface not facing the support), and the phosphor layer is chemically treated. Protects against alteration or physical shock.

[0003]

2. Description of the Related Art A phosphor-containing resin layer comprises a binder which contains and supports phosphor particles in a dispersed state. The attachment of the phosphor-containing resin layer on the support is generally carried out by utilizing a coating method under normal pressure as described below. That is, the phosphor particles and the binder are mixed and dispersed in a suitable solvent to prepare a coating solution, and the coating solution is radiation-sensitized under normal pressure using a coating means such as a doctor blade, a roll coater, or a knife coater. After directly coating on the support of the screen, by removing the solvent from the coating film, or by applying the coating solution in advance on a temporary support such as a glass plate under normal pressure, then remove the solvent from the coating film Then, the phosphor-containing resin thin film is formed, and the phosphor-containing resin layer is attached to the support by peeling it from the temporary support and bonding it to the support of the radiographic intensifying screen. There is.

The phosphor particles in the phosphor-containing resin layer have the property of emitting light with high brightness when excited by radiation such as X-rays. Therefore, the phosphor exhibits high-luminance light emission depending on the amount of radiation passing through the subject, and the radiographic film placed so as to be in contact with the surface of the phosphor-containing resin layer of the radiation intensifying screen is Since the phosphor also sensitizes light, the photographic film can be sufficiently exposed with a relatively small radiation dose.

The radiation intensifying screen having the above-mentioned basic structure is desired to have high sensitivity and to provide an image having good image quality (sharpness, graininess, etc.). Of these, with regard to the sharpness of the image, from the point of obtaining more accurate and detailed information of the subject,
It is desired to develop a radiation intensifying screen in which the sharpness of the obtained image is improved even slightly.

It is an object of the present invention to provide a radiographic intensifying screen which gives an image with particularly improved sharpness.

According to the present invention, the composition ratio of the support, the binder provided on the support and the phosphor is 1: 1 to 1:25.
In a radiographic intensifying screen substantially composed of a phosphor-containing resin layer in the range of (weight ratio, but not including 1:25), the porosity of the phosphor-containing resin layer is completely eliminated.
A radiographic intensifying screen having a pair value of 28% or less and a value of 85% or less of the porosity of the phosphor-containing resin layer having the composition ratio formed by a normal coating method under normal pressure. It is in.

The radiographic intensifying screen of the present invention comprises (1)
The composition ratio of the support and the binder and the phosphor formed on the support by the usual coating method under normal pressure is 1: 1 to 1:25 (weight ratio, but 1:25 is By compressing a sheet that is substantially composed of a phosphor-containing resin layer in the range (not included), the porosity of the phosphor-containing resin layer is set to 85% or less of the porosity before the compression treatment. The production method or (2) the composition ratio of the binder and the phosphor formed by the ordinary coating method under normal pressure is 1: 1 to 1:25 (weight ratio, but not including 1:25). By compressing the phosphor-containing resin layer in the range so that the porosity of the phosphor-containing resin layer is 85% or less of the porosity before the compression treatment, the phosphor-containing resin layer is attached on the support. It can be advantageously produced by the production method.

Next, the present invention will be described in detail. The present invention is
The porosity of the phosphor-containing resin layer of the radiographic intensifying screen in which the composition ratio of the binder and the phosphor is in the range of 1: 1 to 1:25 (weight ratio, but not including 1:25) is By reducing the porosity of the phosphor-containing resin layer having the composition ratio formed by the coating method under normal pressure to a certain level or less, the sharpness of the radiation intensifying screen is significantly improved, that is, the radiation sensitization is performed. When the screen is used, the sharpness of the image formed and recorded on the radiographic film is significantly improved.

That is, when a phosphor-containing resin layer (hereinafter, simply referred to as a phosphor layer) composed of a phosphor and a binder is formed on a support by a usual coating method under normal pressure, the phosphor layer is formed on the support. Is easily mixed with air, resulting in voids. This void is
In particular, it tends to occur around the phosphor particles. Further, as the content of the phosphor with respect to the binder increases, the phosphor particles become denser, and a large amount of voids are likely to occur between the phosphor particles.

By the way, when radiation such as X-rays transmitted through a subject enters the phosphor layer of the radiographic intensifying screen,
The phosphor particles in the phosphor layer absorb the radiation energy corresponding to the transmitted image to be in an excited state, and instantly emit light in the visible region to the near-ultraviolet region having a wavelength different from that of the radiation. The light emitted from the phosphor particles sensitizes the photographic film and contributes to image formation. Generally, as the amount of the phosphor contained in the phosphor layer increases, the amount of light emission increases, and thus the sensitivity improves. On the other hand, the sharpness depends on the thickness of the phosphor layer. That is, the thicker the phosphor layer, the more the light emitted from the phosphor particles is diffused in the phosphor layer, and the light image is recorded on the photographic film in a blurred state. Sharpness decreases. Therefore, if the phosphor layer is thinned, an image with improved sharpness can be obtained.

According to the study by the present inventor, the composition ratio of the binder and the phosphor is 1: 1 to 1:25 (weight ratio, but 1: 2).
In a radiation intensifying screen which is substantially composed of a phosphor-containing resin layer in the range of 5), the porosity of the phosphor layer is formed by a coating method under normal atmospheric pressure. 85% of the porosity of the phosphor-containing resin layer
By making the density of the phosphor in the phosphor layer higher than the density of the phosphor in the conventional radiographic intensifying screen by making the following, as a result, the thickness of the phosphor layer is reduced, and the sharpness of the image is reduced. It has been found that can be significantly improved.

Further, the radiographic intensifying screen of the present invention is
Since the phosphor layer of the conventional radiographic intensifying screen has a phosphor layer having a higher density than that of the phosphor in the phosphor layer of the conventional radiographic intensifying screen, the phosphor layer of the radiographic intensifying screen of the present invention is, for example, a conventional radiographic intensifying screen. If the same layer thickness as the phosphor layer of, the phosphor layer of the radiographic intensifying screen of the present invention can contain more phosphor particles, and thus the radiographic intensifying screen of the present invention The sensitivity can be improved without lowering the sharpness. That is,
In the comparison of the same sharpness, the radiographic intensifying screen of the present invention has higher sensitivity than the conventional radiographic intensifying screen. On the contrary, in comparison of the same sensitivity, the radiographic intensifying screen of the present invention has higher sharpness than the conventional radiographic intensifying screen.

Furthermore, the radiation intensifying screen of the present invention, which has the same sensitivity and the same sharpness as the conventional radiation intensifying screen by coloring the protective film or the phosphor layer, has a higher image quality than the conventional radiation intensifying screen. Has good graininess.

The radiation sensitizing screen of the present invention having the above-mentioned preferable characteristics can be manufactured, for example, by the following method.

In the radiographic intensifying screen of the present invention,
The phosphor-containing resin layer is basically a layer composed of a binder that contains and supports phosphor particles in a dispersed state.

Various types of phosphor particles are already known. Examples of the radiation-sensitizing phosphor particles that are preferably used in the present invention include particles made of the following substances.

Tungstate phosphor (CaWO ₄ ,
MgWO ₄ , CaWO ₄ : Pb, etc.), terbium-activated rare earth oxysulfide-based phosphor [Y ₂ O ₂ S: Tb, Gd ₂ O ₂
S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O ₂
S: Tb, (Y, Gd) ₂ O ₂ S: Tb, Tm, etc.], terbium-activated rare earth phosphate-based phosphor (YPO ₄ : Tb,
GdPO ₄ : Tb, LaPO ₄ : Tb, etc.), terbium-activated rare earth oxyhalide-based phosphor (LaOBr:
Tb, LaOBr: Tb, Tm, LaOCl: Tb, L
aOCl: Tb, Tm, GdOBr: Tb, GdOC
l: Tb, etc.), thulium-activated rare earth oxyhalide-based phosphors (LaOBr: Tm, LaOCl: Tm, etc.),
Barium Sulfate Phosphor [BaSO ₄ : Pb, BaSO
₄ : Eu ²⁺ , (Ba, Sr) SO ₄ : Eu ^2+, etc.] Divalent europium-activated alkaline earth metal phosphate-based phosphor [Ba ₃ (PO ₄ ) ₂ : Eu ²⁺ , (Ba, Sr) ₃ (P
O ₄ ) ₂ : Eu ^2+, etc.] Divalent europium-activated alkaline earth metal fluoride halide phosphor [BaFCl: Eu]
²⁺ , BaFBr: Eu ²⁺ , BaFCl: Eu ²⁺ , Tb,
BaFBr: Eu ²⁺ , Tb, BaF ₂ · BaCl ₂ · K
Cl: Eu ²⁺ , BaF ₂ · BaCl ₂ · xBaSO ₄ ·
KCl: Eu ²⁺ , (Ba, Mg) F ₂ · BaCl ₂ · K
Cl: Eu ^2+, etc.], an iodide-based phosphor (CsI: Na, C
sI: Tl, NaI, KI: Tl, etc.), a sulfide-based phosphor [ZnS: Ag, (Zn, Cd) S: Ag, (Zn, C)
d) S: Cu, (Zn, Cd) S: Cu, Al, etc.], Hafnium phosphate-based phosphor (HfP ₂ O ₇ : Cu, etc.). However, the phosphor particles used in the present invention are not limited to these, and any phosphor particles that emit light in the visible to near-ultraviolet region upon irradiation with radiation may be used.

Examples of the binder for the phosphor layer include proteins such as gelatin, polysaccharides such as dextran,
Or natural polymeric substances such as gum arabic; and
Polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polymethylmethacrylate, vinyl chloride /
Examples thereof include binders represented by synthetic polymer substances such as vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, and linear polyester. Particularly preferred among such binders are nitrocellulose, linear polyesters, and mixtures of nitrocellulose and linear polyesters.

The phosphor layer can be formed on the support by the following coating method, for example.

First, the phosphor particles and the binder are added to an appropriate solvent and mixed sufficiently to prepare a coating solution in which the phosphor particles are uniformly dispersed in the binder solution.

Examples of the solvent for preparing the coating solution include lower alcohols such as methanol, ethanol, n-propanol and n-butanol; chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone and methyl isobutyl ketone. Examples thereof include ketones; esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether; and mixtures thereof.

The composition ratio of the binder to the radiation sensitizing phosphor particles in the coating liquid varies depending on the characteristics of the intended radiation intensifying screen, the type of phosphor particles, etc., but is 1:
1 to 1:25 (weight ratio, but not including 1:25)
It is preferable to select from the range of, and especially from the range of 1: 8 to 1:22 (weight ratio).

The coating liquid contains a dispersant for improving the dispersibility of the phosphor particles in the coating liquid.
Various additives such as a plasticizer for improving the binding force between the binder and the phosphor particles in the formed phosphor layer may be mixed. Examples of dispersants used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl glycolate, butyl phthalyl butyl glycolate, etc. And a polyester of polyethylene glycol and an aliphatic dibasic acid, such as a polyester of triethylene glycol and adipic acid, a polyester of diethylene glycol and succinic acid, and the like.

The coating solution containing the phosphor particles and the binder prepared as described above is then uniformly coated on the surface of the support to form a coating film of the coating solution. This coating operation can be performed by using an ordinary coating means such as a doctor blade, a roll coater or a knife coater.

Then, the formed coating film is gradually heated and dried to complete the formation of the phosphor layer on the support. The layer thickness of the phosphor layer varies depending on the characteristics of the intended radiation intensifying screen, the type of phosphor particles, the mixing ratio of the binder and the phosphor particles, etc., but is usually 20 μm to 1 mm. However, this layer thickness is 50 to 500 μm.
It is preferably m.

The phosphor-containing resin layer does not necessarily have to be formed by directly applying the coating liquid on the support as described above, and for example, separately, a sheet such as a glass plate, a metal plate or a plastic sheet ( (Temporary support) A coating solution is applied on the support and dried to form a phosphor layer, and then the support is pressed onto the support or an adhesive is used to separate the support and the phosphor layer. You may join.

The phosphor-containing resin layer may be colored with a colorant for the purpose of improving the graininess of the resulting radiation intensifying screen.

The support used in the present invention can be arbitrarily selected from various materials known as materials for producing a radiographic intensifying screen. Examples of such materials include films of plastic substances such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil and aluminum alloy foil, ordinary paper, baryta paper, resin. Examples thereof include coated paper, pigment paper containing a pigment such as titanium dioxide, and paper sized with polyvinyl alcohol. However, in consideration of the characteristics as a radiation intensifying screen, a particularly preferable material for the support in the present invention is a plastic film. This plastic film may be kneaded with a light absorbing substance such as carbon black, or may be kneaded with a light reflecting substance such as titanium dioxide.
The former is a support suitable for a high sharpness type radiographic intensifying screen, and the latter is a support suitable for a high sensitivity type radiographic intensifying screen.

In the known radiation intensifying screen, the support on the side where the phosphor layer is provided in order to strengthen the bond between the support and the phosphor layer, or to improve the sensitivity or image quality as the radiation intensifying screen. A high molecular substance such as gelatin is applied to the surface to form an adhesion-imparting layer,
Alternatively, a light reflecting layer made of a light reflecting substance such as titanium dioxide or a light absorbing layer made of a light absorbing substance such as carbon black is also provided. Further, in a radiographic intensifying screen used for industrial radiography for the purpose of nondestructive inspection of a substance, a lead foil, a lead alloy is used on the surface of a support on which a phosphor layer is provided for the purpose of removing scattered radiation. It is also practiced to provide metal foil such as foil and tin foil. The support used in the present invention can also be provided with these various layers.

Further, for the purpose of improving the sharpness of the obtained image, the surface of the support on the side of the phosphor layer (on the surface of the support on the side of the phosphor layer, an adhesion imparting layer, a light reflection layer, a light absorption layer, Alternatively, when a metal foil or the like is provided, it means the surface thereof, and it is possible to form unevenness, and those configurations are arbitrarily selected according to the desired purpose and application of the radiation intensifying screen. can do.

The porosity of the phosphor-containing resin layer formed on the support as described above can be theoretically determined by the following formula (I).

[0033] _{(a + b) ρ x ρ} y V-A (aρ y + bρ x) Vair / V = ────────────────────── - - (I) V [(a + b) ρ x ρ y - aρ y ρair - bρ x ρair] ( However, V: total volume of the phosphor layer Vair: air volume a in the phosphor layer: all of the phosphor Weight ρ _x : Density of phosphor ρ _y : Density of binder ρ air: Density of air a: Weight of phosphor b: Weight of binder)

In expression (I), since ρair is ˜0, expression (I) can be approximately represented by expression (II) below.

[0035] _{(a + b) ρ x ρ} y V-A (aρ y + bρ x) Vair / V = ─────────────────── --- (II ) V [(a + b) ρ _x ρ _y ] (where V, Vair, A, ρ _x , ρ _y , a, and b
Is the same as the formula (I))

In the present invention, the porosity of the phosphor-containing resin layer was calculated by the above formula (II).

As an example, the formation of a phosphor-containing resin layer consisting of a terbium-activated gadolinium oxysulfide phosphor and a mixture of a linear polyester and nitrocellulose as a binder on a support is carried out by the usual conventional method described above. It is carried out by a coating method under pressure, and specifically, for example, as follows.

A mixture of linear polyester and nitrocellulose and a terbium activated gadolinium oxysulfide phosphor (G
d ₂ O ₂ S: Tb) particles were sufficiently mixed in a methyl ethyl ketone using a propeller mixer so that the composition ratio was 1:20 (weight ratio), and the viscosity was 30 PS (25 ° C.).
To prepare a coating solution. This coating solution was evenly coated on polyethylene terephthalate (support) using a doctor blade, and then placed in a drier, and the temperature inside the device was set to 25 ° C.
To 100 ° C. and the coating film is dried to form a phosphor-containing resin layer on the support.

The void ratio of the phosphor-containing resin layer having the composition ratio of the binder and the phosphor thus formed of 1:20 is 2
It was 5.8%. Further, the void ratio of the phosphor-containing resin layer having a composition ratio of the binder and the phosphor of 1:10, which was formed in the same manner as above except that the amounts of the binder and the phosphor used were changed, was 10. It was 7%.

The above-mentioned phosphor-containing resin layer is a typical example of a phosphor layer formed by a normal coating method under normal pressure, and the binder, phosphor particles, solvent, etc. used may be changed. However, the porosity of the obtained phosphor layer does not change significantly. Moreover, in the calculation of the porosity of the formula (II),
The amount of additive added to the coating liquid is very small and can be ignored. Furthermore, the porosity of the phosphor layer is not significantly affected by changes in coating conditions as long as it is within the range of coating operations that are normally performed.

Therefore, the maximum factor that changes the porosity of the phosphor-containing resin layer is that the composition ratio of the binder and the phosphor [from the definition of the formula (II) is b as is clear from the formula (II). :
a, weight ratio]. As the ratio of the phosphor particles to the binder in the phosphor-containing resin layer increases, the average distance between the phosphor particles dispersed in the binder becomes shorter and voids are more likely to occur between them. Therefore, the porosity of the phosphor-containing resin layer tends to increase as the amount of phosphor increases.

In the production of the radiation intensifying screen of the present invention, next, the voids are reduced by, for example, removing a part of the air mixed in the phosphor layer. The reduction of the voids is performed, for example, by compressing the phosphor layer.

The compression treatment of the phosphor layer is generally 100 to 1
The heating is performed at a pressure in the range of 500 kg / cm ² at a temperature in the range of room temperature to the melting point of the phosphor layer. The compression time is preferably in the range of 30 seconds to 5 minutes. A preferred pressure is 100 to 1000 kg / cm ² ,
A particularly preferable pressure is 300 to 700 kg / cm ² . The preferable temperature is 50 to 120 ° C., though it depends on the binder used and the like.

Examples of the compression apparatus used for the compression treatment of the present invention include generally known ones such as a calender roll and a hot press. For example, the compression treatment with a calendar roll is performed by passing a sheet composed of a support and a phosphor layer at a constant speed between rollers heated to a constant temperature. The compression treatment by hot pressing is performed by fixing the sheet between two metal plates heated to a constant temperature and then applying a constant pressure from both sides for a certain period of time. However, the compression device used in the present invention is
The sheet is not limited to these, and any sheet can be used as long as the sheet can be compressed while being heated.

For example, when the phosphor-containing resin thin film formed on the temporary support is compressed, it can be performed before the thin film is attached to the support of the radiation intensifying screen. In that case, the phosphor-containing resin thin film alone or a composite sheet of the phosphor-containing resin thin film and the temporary support is compressed, and then the compressed phosphor-containing resin thin film is radiation-sensitized. It is attached to the screen support.

In a usual radiation intensifying screen, a transparent protective film for physically and chemically protecting the phosphor layer is provided on the surface of the phosphor layer on the side opposite to the side in contact with the support. It is provided. It is preferable to install such a transparent protective film also in the radiation intensifying screen of the present invention.

The transparent protective film is, for example, cellulose acetate,
Cellulose derivatives such as nitrocellulose; or transparent polymeric substances such as polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, and other transparent polymeric substances dissolved in a suitable solvent It can be formed by a method of applying the solution prepared in this way to the surface of the phosphor layer. Alternatively, it can also be formed by a method of adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, vinylidene chloride, polyamide or the like to the surface of the phosphor layer with an appropriate adhesive. The thickness of the transparent protective film thus formed is preferably about 3 to 20 μm.

The transparent protective film may be colored with a colorant for the purpose of improving the graininess of the resulting radiation intensifying screen.

The phosphor-containing resin layer of the radiation intensifying screen of the present invention produced by the method represented by the above-mentioned method (the composition ratio of the binder and the phosphor is 1: 1 to 1).
The range of 1:25, but not including 1:25) is 85% or less of the porosity of the phosphor-containing resin layer having the composition ratio and formed by a normal coating method under normal pressure.
The void ratio (absolute value) of the phosphor-containing resin layer thus obtained generally does not exceed 28%.

By reducing the porosity of the phosphor-containing resin layer in the radiation intensifying screen as described above, the density of the phosphors in the phosphor layer is increased, and thus when the amount of the phosphor used is constant, the phosphor layer is Becomes thin, and the sharpness of the obtained image is significantly improved.

Next, examples and comparative examples of the present invention will be described. However, each of these examples does not limit the present invention.

[0052]

EXAMPLES Example 1 A mixture (binder) of a linear polyester resin and nitrocellulose having a nitrification degree of 11.5% and a terbium-activated gadolinium oxysulfide phosphor (Gd ₂ O ₂ S :) for radiation sensitization. Tb) particles are mixed at a weight composition ratio of 1:20, methyl ethyl ketone is added, and then the mixture is sufficiently stirred and mixed using a propeller mixer so that the phosphor particles are uniformly dispersed and have a viscosity of 30 PS (25 ° C.). ) Was prepared. Next, a polyethylene terephthalate sheet in which titanium dioxide was kneaded (support, thickness: 250 μm
m) was placed horizontally on a glass plate, and the coating solution was uniformly applied onto this support using a doctor blade. After coating, the support on which the coating film was formed was placed in a dryer, and the temperature inside the dryer was gradually raised from 25 ° C. to 100 ° C. to dry the coating film. In this way, a sheet comprising a support and a fluorescent layer having a layer thickness of about 120 μm provided on the support was obtained.

Then, a sheet comprising a support and a phosphor layer formed on one surface of the support was compressed with a calender roll at a pressure of 620 kg / cm ² and a temperature of 100 ° C.

A transparent film of polyethylene terephthalate (thickness: 12
μm, a polyester adhesive is applied) with the adhesive layer side facing down to form a transparent protective film, and the transparent protective film is composed of a support, a phosphor layer, and a transparent protective film. Manufactured radiographic intensifying screen.

Example 2 The same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support was used, and a pressure of 520 kg / cm ² and 1 were applied.
A radiation intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in the method of Example 1 except that compression was performed at a temperature of 00 ° C.

[Example 3] The same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support was subjected to a pressure of 420 kg / cm ² and 1
A radiation intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in the method of Example 1 except that compression was performed at a temperature of 00 ° C.

Example 4 The same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support was used, and a pressure of 620 kg / cm ² and 8 were applied.
A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in Example 1 except that compression was performed at a temperature of 0 ° C.

Example 5 The same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support was used, and a pressure of 520 kg / cm ² and 8 were applied.
A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in Example 1 except that compression was performed at a temperature of 0 ° C.

Example 6 The same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support was used, and a pressure of 420 kg / cm ² and 8 were applied.
A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in Example 1 except that compression was performed at a temperature of 0 ° C.

[Comparative Example 1] Similar to the method of Example 1 except that the same sheet as the sheet made of the support produced in Example 1 and the phosphor layer provided on the support is not compressed. By performing various treatments, the support, the phosphor layer,
And a radiographic intensifying screen composed of a transparent protective film.

The measured volume and weight of the phosphor layer of each of the radiographic intensifying screens produced as described above,
Since the density of the phosphor density (7.5g / cm ³⁾ and a binder was used (1.258g / cm ^3), was calculated porosity of phosphor-containing resin layer, respectively by formula (II) .

The results obtained for each phosphor-containing resin layer are shown in Table 1.

[0063]

Example 1 manufactured as described above
And the radiographic intensifying screen of Comparative Example 1 was evaluated by the Image Sharpness Test described below. That is, a radiographic intensifying screen and an X-ray photographic film were pressure-bonded in a cassette, X-ray photography was performed through a resolution chart, and the modulation transfer function (MTF) of the resulting X-ray photography was measured.

The obtained results are shown together in the form of a graph in the drawing.

In the drawing, A is the relationship between the spatial frequency and the MTF value in the radiographic intensifying screen of Example 1, and B is
Represents the relationship between the spatial frequency and the MTF value in the radiographic intensifying screen of Comparative Example 1.

Table 2 shows the results obtained (MTF value at spatial frequency of 2 cycles / mm) for each of the radiographic intensifying screens.

[0068]

Example 7 Mixture of linear polyester resin and nitrocellulose having a nitrification degree of 11.5% (binder)
The same treatment as in the method of Example 1 was performed except that the radiation sensitizing terbium-activated gadolinium oxysulfide phosphor (Gd ₂ O ₂ S: Tb) particles were mixed at a weight composition ratio of 1:10. By carrying out, a radiation intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced.

Example 8 The same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was used, and a pressure of 520 kg / cm ² and 1 were applied.
A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by carrying out the same treatment as in Example 7, except for compressing at a temperature of 00 ° C.

[Example 9] The same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was subjected to a pressure of 420 kg / cm ² and 1
A radiation intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by carrying out the same treatment as in Example 7 except that compression was carried out at a temperature of 00 ° C.

Example 10 The same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was used, and a pressure of 620 kg / cm ² and a temperature of 80 ° C. were used. A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in the method of Example 7 except that the radiation intensifying screen was used.

Example 11 The same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was applied to a sheet having a pressure of 520 kg / cm ² and a temperature of 80 ° C. A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in the method of Example 7 except that the radiation intensifying screen was used.

Example 12 The same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was used, and a pressure of 420 kg / cm ² and a temperature of 80 ° C. were used. A radiographic intensifying screen composed of a support, a phosphor layer, and a transparent protective film was produced by performing the same treatment as in the method of Example 7 except that the radiation intensifying screen was used.

[Comparative Example 2] The same method as in Example 7 was repeated except that the same sheet as the sheet made of the support produced in Example 7 and the phosphor layer provided on the support was not compressed. By performing various treatments, the support, the phosphor layer,
And a radiographic intensifying screen composed of a transparent protective film.

The porosity of the phosphor-containing resin layer of each radiation intensifying screen manufactured as described above was calculated and calculated by the same method as described above.

The results obtained for each phosphor-containing resin layer are shown in Table 3.

[0078]

Example 7 manufactured as described above
And the radiographic intensifying screen of Comparative Example 2 was evaluated by the image sharpness test described above.

Results obtained for each radiographic intensifying screen (MT at spatial frequency 2 cycles / mm
The F value) is shown in Table 4.

[0081]

[Brief description of drawings]

1 is a graph of the modulation transfer function (MTF) of radiographs obtained with the radiographic intensifying screens manufactured in Example 1 and Comparative Example 1. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-38699 (JP, A) JP-B-55-7575 (JP, B2) JOURNAL OF THE ELE CTROCHEMICAL SOCIETY Y, Vol. 122, No. 8 (1975-8) (US) P. 1089-10

Claims (2)

[Claims] 1. A fluorescent material having a composition ratio of a support, a binder provided on the support and a phosphor of 1: 1 to 1:25 (weight ratio, but not including 1:25). In a radiographic intensifying screen substantially composed of a phosphor-containing resin layer, the absolute value of the porosity of the phosphor-containing resin layer is 28%.
Hereinafter, and radiographic intensifying screens, characterized in that it has a normal 85% the following values of the porosity of the phosphor-containing resin layer of the composition ratio is formed by a coating method at normal pressure. 2. The phosphor is a terbium-activated rare earth oxysulfide system.
The radiographic intensifying screen according to claim 1, which is a phosphor .