JPH1184097A - Radiation sensitized screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a screen superior in sensitivity, clarity and grain state by mixing phosphor constituting phosphor layer with a plurality of specific equations. SOLUTION: The Ln in the equation I is one kind of rare earth elements selected among Y, Lu, Gd and La and more desirably Y or Gd and most desirably Y. M<1> is at least one of divalent metal element selected among Be, Mg, Ca, Sr, Be, Zn and Cd and more desirably Sr. M<2> in the equation II means at least one of divalent element selected among Sr or Ca and X is at least one kind of halogen elements selected among Br and I. If Br or I is contained, sensitivity increases but afterglow performance gets worse, the container is weak for humidity and causes sensitivity lowering with time. Therefore, the contents of them is desirably less or below 50% in total. The fluorescent body in the equation I and the equation II is produced from the mixture of equation I and II or layer consisting of phosphor is produced by layering the different layer in the adjacent layer with different fluorescent kind in the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic intensifying screen, and more particularly to a radiographic intensifying screen for providing a high-sensitivity, high-sharpness image.

[0002]

2. Description of the Related Art Radiation intensifying screens (hereinafter simply referred to as "radiation intensifying screens") are used for medical radiography such as X-ray radiography for medical diagnosis and industrial radiography for nondestructive inspection of substances. A radiographic method in which a silver halide photographic light-sensitive material (hereinafter, also simply referred to as a light-sensitive material) is combined with a screen.

[0003] In radiography, radiation transmitted through or emitted from a subject is irradiated on a phosphor of a screen to excite the phosphor to convert the radiation into visible light, thereby forming a radiation image on a photosensitive material to perform a diagnosis. It is to be inspected.

The screen has a basic structure comprising a support, a phosphor layer and a protective layer provided on one surface of the support, and the phosphor layer is made of a binder containing phosphor particles in a dispersed state. The phosphor particles emit high-luminance light when excited by radiation such as X-rays, and the light-sensitive material placed on top of the phosphor layer of the screen is superposed by the light emission of the phosphor. Due to the photosensitivity, sufficient imagewise exposure can be given to the photosensitive material with a relatively small radiation dose.

Generally, the image quality (sharpness, granularity) of an image obtained by a photographing system largely depends on the characteristics of a screen incorporated in the system, and the screen gives an image with excellent image quality. It is hoped that it is.

For example, in order to increase the granularity of an image, calcium tungstate (CaW) is added to the phosphor layer.
O ₄ ) and rare earth tantalate (YNb _x Ta _1-x O ₄ , Lu
_{Nb x Ta 1-x O 4} , Y 1-y Tm y TaO 4) with a mixture of phosphor (the latter phosphors containing 5 to 75 wt%) method using a is disclosed in KOKOKU No. 5-17518 And also
Calcium tungstate on the protective layer side and rare earth tantalate phosphor on the support side (M _a Ln _{1- (2/3) a} DO ₄ : xTm
^{3 +} where M is Be, Mg, Ca, Sr, Ba, Zn,
At least one divalent element selected from Cd, Ln is at least one element selected from Y, Gd, La, and Lu; D is at least one element selected from Ta and Nb; ), And x is 0 or more and 0.05 or less). A screen comprising a phosphor is disclosed in JP-B-7-56023, but the sensitivity, sharpness, and granularity are insufficient. A screen excellent in sharpness and granularity has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a screen having excellent sensitivity, sharpness and granularity.

[0008]

The above problems are as follows. In a radiation intensifying screen in which a phosphor layer and a protective layer are arranged in this order on a support, the phosphor constituting the phosphor layer is a phosphor represented by the following general formula (1) and a phosphor represented by the following general formula ( A radiation intensifying screen comprising a mixture of the phosphors represented by 2).

[0009] General formula _{(1) Ln 1-ax M} 1 a Ta 1-p Nb p O 4-a / 2: xA 3+ ( wherein, Ln is Y, Lu, Gd, at least one selected from La A rare earth element, M ¹ is Be, Mg, C
a, at least one divalent metal element selected from a, Sr, Ba, Zn, and Cd, and A is at least one rare earth element selected from Tm, Gd, and Tb [where Ln is G
A does not include Gd when d is included).

0 ≦ a ≦ 1, 0 ≦ x ≦ 0.1, a + x ≦ 1
And 0 ≦ p ≦ 1. ) General formula _{(2) Ba 1-by M} 2 b FCl 1-z X z: yEu 2+ ( wherein, ^{M 2} is Sr, at least one trivalent metal element selected from Ca, X is Br, the I At least one selected halogen atom, 0 ≦ b ≦ 1, 0.001
≦ y ≦ 0.2, b + y ≦ 1, and 0 ≦ z ≦ 0.5).

2. In a radiation intensifying screen in which a plurality of phosphor layers and a protective layer sequentially laminated on a support are arranged in this order, the phosphor constituting each phosphor layer is represented by the general formula (1). A radiation intensifying screen comprising a phosphor or a phosphor represented by the general formula (2), wherein phosphor types in adjacent phosphor layers are different from each other.

Hereinafter, the present invention will be described in detail.

In the general formula (1), Ln is Y, Lu,
It is at least one rare earth element selected from Gd and La, preferably Y (yttrium) and Gd (gadolinium), and particularly preferably Y. M ¹ is B
e, at least one divalent metal element selected from Mg, Ca, Sr, Ba, Zn, and Cd;
r (strontium). A is at least one rare earth element selected from Tm, Gd, and Tb, and is preferably Tm (thulium). [However, when Ln contains Gd, A does not contain Gd]. a satisfies 0 ≦ a ≦ 1, preferably 0 ≦ a ≦ 0.3, and when a is 0.3 or less, sensitivity and sharpness are good. x is 0 ≦ x ≦ 0.1,
Preferably, 0 ≦ x ≦ 0.05, and at 0.05 or less, the sensitivity is good. a + x ≦ 1, preferably a + x ≦
0.35. p is 0 ≦ p ≦ 1, preferably 0
.Ltoreq.p.ltoreq.0.05, and sharpness was further excellent at 0.05 or less.

In the general formula (2), M ² is Sr, Ca
At least one divalent metal element selected from
X is at least one halogen atom selected from Br and I. However, when Br or I is contained, the sensitivity is increased, but the afterglow is deteriorated, the humidity is weak, and the sensitivity decreases over time. For this reason, it is preferable that the content of these elements be 50% or less in total. b is 0 ≦ b ≦ 1, preferably 0 ≦ b ≦ 0.3, and y is 0.01 ≦ y ≦ 0.
2, preferably 0.01 ≦ y ≦ 0.05.
b + y ≦ 1, preferably b + y ≦ 0.5.

The phosphor layer of the screen of the present invention may be prepared from a mixture of the phosphors of the general formulas (1) and (2) or may be formed of a phosphor layer of the general formula (1) and a phosphor layer of the general formula (1). It is characterized in that the phosphor layer made of the phosphor of the formula (2) is produced by laminating layers of different phosphor types in adjacent phosphor layers.

Here, that the phosphor types are different from each other means a phosphor represented by the general formula (1) or (2).

In the screen of the present invention, the content of the phosphor represented by the general formula (1) in the phosphor layer is 20 to 95% by weight.
And more preferably 50 to 95% by weight. In the present invention, it is preferable that the average particle size of the phosphor of the applied phosphor layer is smaller as it is closer to the support, and one is to appropriately mix the classified radiation phosphor and the binder resin, Further, an appropriate amount of a solvent is added to this, a phosphor coating solution having an optimum viscosity is prepared by the number of the phosphor layers, and the phosphor coating solution is overlaid so that the average particle size on the support side becomes small.

As another method, after a phosphor coating solution is coated on a temporary support, large particles are allowed to settle to the lower part according to Stoke's law over a sufficient time, and dried with a gradient particle diameter. One-layer coating may be applied. In this case, the phosphor layer having a gradient particle diameter such that the average particle diameter becomes smaller as the substrate is closer to the support can be obtained by bonding the surface far from the temporary support to the support with the bonding surface.

The average particle size of the phosphor in the layer closest to the support is preferably 1 to 5 μm, and the average particle size of the phosphor in the layer farthest from the support is preferably 8 to 20 μm.

As a method for classifying the phosphor particle size, a sieve method using a sieve, elutriation performed by placing the phosphor in a nylon mesh bag and shaking in water or pouring the phosphor coating solution through the sieve is used. And a sedimentation method in which the phosphor is left standing after stirring in water, and after a certain time, the supernatant or the precipitate is removed.

The method of measuring the particle size distribution of the classified phosphor is as follows: volume analysis such as sieving and a Coulter counter; image analysis using a microscope; sedimentation by gravity and centrifugation; Surface area analysis methods such as the Cozeny Kalman method and the Nudesen method, BE
There are adsorption methods such as the T method and the flow method, and methods utilizing electromagnetic wave scattering such as the light diffraction method.

It is preferable that the screen having the gradient particle size structure has a multilayer structure (a plurality of phosphor layers) because the mixing ratio of the phosphor and the average particle diameter of the phosphor can be easily controlled. In particular, the manufacturing method is simple. In this case, the layer configuration is preferably a two- to five-layer structure, and particularly preferably a two- to three-layer structure.

Examples of the binder resin used in the phosphor coating solution include polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polybutadiene-based thermoplastic elastomers. Plastic elastomer, ethylene vinyl acetate thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, natural rubber thermoplastic elastomer, fluoro rubber thermoplastic elastomer, polyisoprene thermoplastic elastomer, chlorinated polyethylene thermoplastic elastomer, styrene Butadiene rubber and silicone rubber-based thermoplastic elastomer.

Of these, polyurethane-based thermoplastic elastomers and polyester-based thermoplastic elastomers have good dispersibility since they have a strong bonding force with the phosphor.
Further, it is preferable because it has high ductility and the bending resistance of the radiation intensifying screen becomes good.

Examples of the solvent used in the phosphor coating solution include lower alcohols such as methanol, ethanol, n-propanol and n-butanol, hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride, acetone, methyl ethyl ketone, and the like. Ketones such as methyl isobutyl ketone; aromatic compounds such as toluene and benzene; esters of lower fatty acids such as methyl acetate, ethyl acetate and butyl acetate with lower alcohols; ethers such as dioxane, ethylene glycol monoethyl ester and ethylene glycol monomethyl ester And mixtures thereof.

Examples of dispersants used in the phosphor of the present invention include, for example, phthalic acid, stearic acid, caproic acid,
Examples include lipophilic surfactants.

Examples of the plasticizer used in the coating solution of the phosphor of the present invention include phosphoric esters such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate; phthalic esters such as diethyl phthalate and dimethoxyethyl phthalate; Glycolic acid esters such as ethylphthalylethyl glycolate and butylphthalbutyl glycolate, polyesters of triethylene glycol and adipic acid, polyesters of polyethylene glycol such as polyester of diethylene glycol and succinic acid, and polyesters of aliphatic dibasic acid, etc. Can be mentioned.

When preparing a radiographic intensifying screen, first, a binder and a phosphor are added to an appropriate organic solvent, and the mixture is stirred and mixed using a disper or a ball mill to uniformly disperse the phosphor in the binder. Prepare a coating solution. A coating film is formed by simultaneously and simultaneously applying a plurality of coating solutions prepared as described above on the surface of the support.

This coating operation can be performed by using a usual coating means, for example, a doctor blade, a roll coater, a knife coater or the like.

Next, the formed coating film is dried by gradually heating to complete the formation of the phosphor layer on the support. Alternatively, a multilayer phosphor layer may be formed on the support by repeating the operation of coating and drying each coating liquid one by one in order.

Further, the phosphor layer does not necessarily need to be formed by directly applying a coating solution on the support as described above, and the coating solution may be applied on another temporary support or a protective layer in the same manner as described above. After the phosphor layer is formed by drying, the phosphor layer may be bonded to the support by pressing the phosphor layer on the support or using an adhesive.

As the support or the temporary support, for example, those made of various materials such as glass, wool, cotton, paper, and metal can be used. What can be processed into a sheet or a roll is preferred. From this point, for example, plastic films such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate film, metal sheets such as aluminum foil and aluminum alloy foil, general paper, and photographic base paper, for example. Base paper for printing such as coated paper or art paper, baryta paper, resin coated paper, paper sized with polysaccharides as described in Belgian Patent 784,615, pigments such as titanium dioxide Pigmented paper containing, and processed paper such as paper sized with polyvinyl alcohol are particularly preferred.

The thickness of the phosphor layer varies depending on the characteristics of the intended radiographic intensifying screen, the kind of the phosphor, the mixing ratio between the binder and the phosphor, etc., but is usually in the range of 20 μm to 1 mm. Preferably it is in the range of 50 to 300 μm.

The thickness of the phosphor layer must be uniform so as not to cause unevenness in light emission intensity.

In order to strengthen the bond between the support and the phosphor layer,
Alternatively, in order to improve the sensitivity or image quality (sharpness, granularity, etc.) of the radiation intensifying screen, a polymer material such as gelatin is applied to the surface of the support on which the phosphor layer is provided to impart adhesiveness. An undercoat layer may be provided, a light reflecting layer made of a light reflecting material such as titanium dioxide, or a light absorbing layer made of a light absorbing material such as carbon black.

The structure can be arbitrarily selected according to the purpose, application, and the like.

In order to increase the filling rate of the phosphor in the phosphor layer,
The obtained phosphor layer may be placed on a support and compressed at a temperature higher than the softening temperature or melting point of the binder. In this case, it is effective to prepare the phosphor layer on a temporary support and adhere the phosphor layer on the support while compressing the obtained phosphor layer.

As a compression apparatus used for the compression processing, generally known apparatuses such as a calender roll and a hot press can be mentioned.

For example, the compression treatment by a calender roll is carried out by placing the obtained phosphor layer on a support and passing it at a constant speed between rollers heated to a temperature higher than the softening temperature or melting point of the binder. . However, the compression device is not limited to these, and any device may be used as long as it can compress the sheet while heating it.

The pressure during compression is preferably at least 30 kgw / cm ² . The compression may be performed after the protective layer is applied.

Usually, the radiation intensifying screen is provided with a transparent protective layer for physically and chemically protecting the phosphor layer on the surface of the phosphor layer opposite to the side in contact with the support described above. . Such a transparent protective layer is preferably applied to the present invention from the viewpoint of the effect of the present invention. The thickness of the protective layer is generally in the range of 2 to 20 μm.

The transparent protective layer is made of, for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene,
A plastic sheet made of polyvinylidene chloride, polyamide, etc., and a protective layer forming sheet such as a transparent glass plate are separately prepared and formed by a method such as bonding to a surface of the phosphor layer using a suitable adhesive. Can be. Alternatively, a cellulose derivative such as cellulose acetate and nitrocellulose, or a synthetic polymer such as polymethyl methacrylate, polyethylene terephthalate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, and vinyl chloride / vinyl acetate copolymer are dissolved in an appropriate solvent. The solution prepared as described above can be formed by applying the solution to the surface of the phosphor layer.

These polymer substances can be used alone or in combination. When the protective layer is formed by coating, it is desirable to add a crosslinking agent immediately before coating.

The protective layer has a thickness of 10 formed on the phosphor layer.
It is preferably a transparent synthetic resin layer having a thickness of not more than μm. By using such a thin protective layer, particularly in the case of a radiographic intensifying screen, the distance from the phosphor to the silver halide emulsion is shortened, which contributes to the improvement of the sharpness of the obtained radiographic image.

The performance of the radiation intensifying screen was evaluated by the following method.

1) Sensitivity A green-sensitized SR-IC single-sided photosensitive material manufactured by Konica Corporation was placed in contact with an intensifying screen to be measured, and placed at a position 2 m from an X-ray tube. A light-sensitive material was arranged in front of the X-ray source, and an intensifying screen was arranged behind it.
The X-ray tube used was DRX-2724 HD-
P is used to generate X-rays through a 3 mm aluminum equivalent material, including a stop, with a focus spot size of 0.6 mm × 0.6 mm using a tungsten target and a focus spot size. A voltage of 80 KV was applied to the three phases by a pulse generator, and X-rays passed through a 7 cm water filter having absorption substantially equivalent to a human body were used as a light source. The sensitivity was measured by changing the amount of X-ray exposure by the distance method, and performing step exposure with a width of logE = 0.15. After exposure, develop the photosensitive material,
A measurement sample was obtained. The development process is performed by a Konica roller transport type automatic developing machine (SRX-502) using a Konica SR-D
At 35 ° C. using an F developer, fixing is performed using a fixing solution (ammonium thiosulfate (70% weight / volume) 200 ml, sodium sulfite 20 g, boric acid 8 g, disodium ethylenediaminetetraacetate (dihydrate) 0.1 g, aluminum sulfate 15).
g, sulfuric acid 2 g, and glacial acetic acid 22 g, water was added to make up to 1 liter, and the pH was adjusted to 10.02) at 25 ° C. for a total treatment time of 45 seconds. Perform a concentration measurement on the measurement sample with visible light,
A characteristic curve was obtained. From the characteristic curve, the minimum density (Dmi
The sensitivity was represented by the reciprocal of the amount of X-ray exposure necessary to obtain a density obtained by adding 1.0 to n), and the relative sensitivity was shown by setting the sensitivity of the comparative screen to 100.

2) Sharpness In the same manner as described above, a rectangular chart for MTF measurement (made of molybdenum, thickness: 80 μm, spatial frequency: 0 / mm)
10 lines / mm) were photographed and developed. Next, the obtained measurement sample was scanned with a microdensitometer. At this time, the aperture used a slit of 10 μm in the scanning direction and 1000 μm in the direction perpendicular thereto, and the density profile was measured at a sampling interval of 10 μm. This operation 2
The average value was calculated by repeating 0 times, and this was used as the base profile for calculating the CTF. Thereafter, the peak of the rectangular wave at each frequency of the density profile is detected, the density contrast at each frequency is calculated, and further the Koltzmann correction is performed to obtain the MTF.
And expressed as relative values. Note that the MTF has a spatial frequency of 2.
A value of 0 / mm was measured. Accordingly, the higher the relative value, the better the sharpness.

3) Granularity Photographing and developing were performed in the same manner as in the sensitivity measurement, and a measurement sample having a density after development of 1.0 ± 0.1 was obtained by adjusting the amount of exposure. Next, the obtained measurement sample was scanned with a microdensitometer. At this time, the aperture is 1 in the scanning direction.
The density profile was measured at a sampling interval of 10 μm using a slit of 00 μm and a vertical direction of 200 μm, and 5000 points of data were acquired. In order to increase the measurement accuracy, this operation was repeated 10 times, and the RMS granularity was determined based on these measurement data, and expressed as a relative value with the RMS value of the comparative screen being 100.
For "RMS" granularity see T.W. H. James Version: T
he Theory of The Photograph
hic Process pages 619-620 (1977)
Year, Macmillan). In addition,
The smaller the relative value, the better the graininess.

[0049]

Hereinafter, embodiments of the present invention will be described.
As a matter of course, the present invention is not limited to the embodiments described below.

Example 1 Preparation of Comparative Screen (1) Classification was performed by elutriation, and (Y _0.98 , Sr _0.02 ) Ta _0.98 Nb having an average particle size of 3 μm measured by a Coulter counter.
_0.02 O _3.99 phosphor 400g, binder polyurethane 10
g, solvent methyl ethyl ketone 50 g in a ball mill 6
After mixing and dispersing for a time, a phosphor coating solution was prepared. The coating solution was dried on a polyethylene terephthalate (250 μm) support placed horizontally on a glass plate to have a layer thickness of 120 μm.
To form a phosphor layer by applying evenly with a knife coater, and apply a 8 μm-thick transparent polyethylene terephthalate film having a polyester-based adhesive applied to one side on the phosphor layer with the adhesive down. By bonding, a comparative screen (1) was produced as a protective layer.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Comparative Screen (2) In the preparation of Comparative Screen (1), the phosphor was prepared by using (Y _0.96 , Sr _0.02 ) TaO _3.99 having an average particle size of 3 μm:
A comparative screen (2) was produced in the same manner as the comparative screen (1) except that the screen was replaced with 0.02 Tm ³⁺ .

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Comparative Screen (3) Same as Comparative Screen (1) except that the phosphor was changed to Ba _0.95 FCl: 0.05 Eu ²⁺ having an average particle diameter of 3 μm in the preparation of Comparative Screen (1). The comparative screen (3) was produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (4) of the Present Invention A phosphor (Y _0.98 , Sr _0.02 ) Ta having an average particle size of 3 μm, which was classified by elutriation and measured by a Coulter counter.
_0.98 Nb _0.02 O _3.99 and phosphor Ba _0.95 having an average particle size of 3 μm
400 g of FCl: 0.05Eu ²⁺ was mixed at a weight ratio of 6: 4, and 10 g of a binder polyurethane and 50 g of a solvent methyl ethyl ketone were mixed and dispersed in a ball mill for 6 hours to prepare a phosphor coating solution. The coating solution was uniformly applied with a knife coater on a polyethylene terephthalate (250 μm) support placed horizontally on a glass plate so as to have a layer thickness of 120 μm after drying to form a phosphor layer, and a polyester-based material was coated on one side. A transparent polyethylene terephthalate film having a thickness of 8 μm to which an adhesive was applied was adhered onto the phosphor layer with the adhesive facing down to produce a screen (4) of the present invention as a protective layer.

Next, the sensitivity, sharpness and granularity were measured by the above-mentioned methods.

Preparation of Screen (5) of the Present Invention In the preparation of the screen (4), the phosphor was prepared by using (Y _0.96 , Sr _0.02 ) TaO _3.99 : 0.0 having an average particle diameter of 3 μm.
Screen (5) of the present invention was produced in the same manner as screen (4) except that 2Tm ³⁺ was used.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (6) of the Present Invention In the preparation of the screen (4), the phosphor was made to have an average particle size of 3
μm (Y _0.90 , Sr _0.02 ) TaO _3.99 : 0.08 Tm
Screen (6) of the present invention was produced in the same manner as screen (4) except that ³⁺ was used.

Preparation of Comparative Screen (7) In the preparation of the screen (4), the phosphor was prepared by using (Y _0.86 , Sr _0.02 ) TaO _3.99 : 0.1 having an average particle diameter of 3 μm.
A comparative screen (7) was produced in the same manner as the screen (4) except that 2Tm ³⁺ was used.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (8) of the Present Invention In the preparation of the screen (4), the phosphor was prepared by using (Y _0.5 , Sr _0.5 ) Ta _0.98 Nb _0.02 O having an average particle diameter of 3 μm.
A screen (8) of the present invention was produced in the same manner as the screen (4) except that the screen was replaced with _3.75 .

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (9) of the Present Invention In the preparation of the screen (4), the phosphor was prepared by using (Y _0.98 , Sr _0.02 ) Ta _0.92 Nb _0.08 O having an average particle size of 3 μm.
Screen (9) of the present invention was produced in the same manner as screen (4) except that _3.99 was used.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (10) of the Present Invention In the preparation of the above-mentioned screen (4), the phosphor was made of Ba _0.75 Sr _0.2 FCl: 0.05 Eu ²⁺ having an average particle diameter of 3 μm.
A screen (10) of the present invention was produced in the same manner as in the screen (4) except that the above was replaced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (11) of the Present Invention In the preparation of the screen (4), the phosphor was changed to Ba _0.55 Sr _0.4 FCl: 0.05 Eu ²⁺ having an average particle diameter of 3 μm.
A screen (11) of the invention was produced in the same manner as the screen (4) except that the above was replaced with

Next, the sensitivity, sharpness and granularity were measured by the above-mentioned methods.

Preparation of Screen (12) of the Present Invention Same as Screen (4), except that the phosphor was changed to Ba _0.85 FCl: 0.15Eu ²⁺ having an average particle diameter of 3 μm in the preparation of Screen (4). Thus, a screen (12) of the present invention was produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Comparative Screen (13) Screen (4) was prepared in the same manner as screen (4) except that the phosphor was changed to Ba _0.75 FCl: 0.25 Eu ²⁺ having an average particle diameter of 3 μm. A comparative screen (13) was prepared.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Comparative Screen (14) The procedure of Screen (4) was the same as that of Screen (4) except that the phosphor was changed to Ba _0.9995 FCl: 0.0005Eu ²⁺ having an average particle diameter of 3 μm. A comparative screen (14) was produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (15) of the Present Invention In the preparation of the screen (4), the phosphor was changed to Ba _0.95 FCl _0.7 Br _0.3 : 0.05 Eu having an average particle diameter of 3 μm.
Screen (15) of the present invention was produced in the same manner as screen (4), except that ²⁺ was used.

Preparation of Screen (16) of the Present Invention In the preparation of the above-mentioned screen (4), the phosphor was changed to Ba _0.95 FC _0.7 Br _0.3 : 0.05 Eu having an average particle diameter of 3 μm.
Screen (16) of the present invention was produced in the same manner as screen (4) except that ²⁺ was used.

Preparation of Screen (17) of the Present Invention In the preparation of the above-mentioned screen (16), the phosphor was changed to Ba _0.95 FCl _0.7 Br _0.15 I _0.15 having an average particle diameter of 3 μm:
Screen (17) of the present invention was made in the same manner as screen (16), except that 0.05Eu ²⁺ was used.

Production of Screen (18) of the Present Invention In the production of the screen (4), the general formula (1)
A screen (18) of the present invention was produced in the same manner as the screen (4) except that the mixing ratio of the phosphors represented by (2) and (3) was 3: 7.

Preparation of Screen (19) of the Present Invention In the preparation of the screen (4), the general formula (1)
A screen (19) of the present invention was produced in the same manner as the screen (4) except that the mixing ratio of the phosphors represented by and (2) was 1: 9.

Preparation of Screen (20) of the Present Invention Preparation of First Layer Phosphor Coating Solution (Y _0.98 , Sr _0.02 ) Ta _0.98 Nb having an average particle size of 3 μm, which was classified by elutriation and measured by a Coulter counter.
_0.02 O _3.99 phosphor and phosphor Ba _0.95 F with average particle size of 3 μm
400 g of Cl: 0.05Eu ²⁺ was mixed at a weight ratio of 6: 4, and 10 g of a binder polyurethane and 50 g of a solvent methyl ethyl ketone were mixed and dispersed in a ball mill for 6 hours to prepare a first layer phosphor coating solution.

Preparation of Second Layer Phosphor Coating Solution Similarly, (Y _0.98 , Sr _0.02 ) Ta having an average particle size of 10 μm was classified by elutriation and measured by a Coulter counter.
_{A 0.98} Nb _0.02 O _3.99 phosphor and a phosphor Ba _0.95 FCl: 0.05 Eu ²⁺ having an average particle size of 10 μm are mixed at a weight ratio of 6: 4 to 4
Then, 10 g of a binder polyurethane and 50 g of a solvent methyl ethyl ketone were mixed and dispersed in a ball mill for 6 hours to prepare a second layer phosphor coating solution.

The coating solution for the first layer was uniformly applied on a polyethylene terephthalate (250 μm) support placed horizontally on a glass plate with a knife coater so that the layer thickness after drying was 60 μm, and the first phosphor was applied. Layers were made.

After drying, the coating liquid for the second layer was evenly applied on the first layer with a knife coater so that the layer thickness after drying was 60 μm (total layer thickness: 120 μm) to produce a second phosphor layer. . Then, a transparent polyethylene terephthalate film having a thickness of 8 μm having a polyester-based adhesive applied to one surface thereof was adhered onto the phosphor layer with the adhesive down, thereby producing a screen (20) of the present invention as a protective layer.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (21) of the Present Invention Preparation of Phosphor Coating Solution for First Layer Phosphor Ba _0.95 FCl having an average particle diameter of 3 μm, which was classified by elutriation and measured by a Coulter counter: 0.05E
400 g of u ²⁺ was mixed and dispersed in a ball mill for 6 hours with 10 g of a binder polyurethane and 50 g of a solvent methyl ethyl ketone to prepare a first layer phosphor coating solution.

Preparation of Phosphor Coating Solution for Second Layer Phosphor (Y _0.98 , Sr _0.02 ) Ta having an average particle diameter of 3 μm, which was classified by elutriation and measured by a Coulter counter.
_0.98 Nb _0.02 O _3.99 400 g of binder polyurethane 10
g, solvent methyl ethyl ketone 50 g in a ball mill 6
The mixture was dispersed for a period of time to prepare a second layer phosphor coating solution.

The coating solution for the first layer was uniformly coated on a polyethylene terephthalate (250 μm) support placed horizontally on a glass plate with a knife coater so that the layer thickness after drying was 40 μm. A body layer was prepared.

After drying, the coating solution for the second layer is uniformly applied on the first layer by a knife coater so that the layer thickness after drying becomes 80 μm (total layer thickness: 120 μm) to form a second phosphor layer. did.

Then, a transparent polyethylene terephthalate film having a thickness of 8 μm having a polyester-based adhesive applied on one side is adhered on the phosphor layer with the adhesive down, and the screen (21) of the present invention is used as a protective layer. Produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Production of Screen (22) of the Present Invention In the production of the radiation intensifying screen (21),
The screen (22) of the present invention was prepared in the same manner as the screen (21) except that (Y _0.98 , Sr _0.02 ) Ta _0.98 Nb _0.02 O _3.99 having an average particle size of 10 μm was used as the phosphor for the second layer. Produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (23) of the Present Invention Preparation of Phosphor Coating Solution for First Layer Phosphor (Y _0.98 , Sr _0.02 ) Ta having an average particle diameter of 3 μm which was classified by elutriation and measured by a Coulter counter.
_0.98 Nb _0.02 O _3.99 400 g of binder polyurethane 10
g, solvent methyl ethyl ketone 50 g in a ball mill 6
The mixture was dispersed for a period of time to prepare a first layer phosphor coating solution.

Preparation of Phosphor Coating Solution for Second Layer Phosphor Ba _0.95 FCl having an average particle diameter of 3 μm, which was classified by elutriation and measured by a Coulter counter: 0.05E
400 g of u ²⁺ was mixed and dispersed in a ball mill for 6 hours with 10 g of a binder polyurethane and 50 g of a solvent methyl ethyl ketone to prepare a second layer phosphor coating solution.

The coating solution for the first layer was uniformly coated on a polyethylene terephthalate (250 μm) support placed horizontally on a glass plate with a knife coater so that the layer thickness after drying was 40 μm. A body layer was prepared.

After drying, the coating solution for the second layer is uniformly applied on the first layer by a knife coater so that the layer thickness after drying is 80 μm (total layer thickness: 120 μm) to form a second phosphor layer. did.

Then, a transparent polyethylene terephthalate film having a thickness of 8 μm having a polyester-based adhesive applied on one side is adhered on the phosphor layer with the adhesive down, and the screen (23) of the present invention is used as a protective layer. Produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

Preparation of Screen (24) of the Present Invention In the preparation of the screen (23), the phosphor of the second layer was added to the phosphor having an average particle diameter of 10 μm (Y _0.98 , S
r _0.02 ) Ta _0.98 Nb _0.02 O _3.99 , except that screen (23) was used in the same manner as screen (23).
4) was produced.

Next, the sensitivity, sharpness and granularity were measured by the methods described above.

The results are summarized in Tables 1 to 3.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

[Table 3]

From Tables 1 to 3, it can be seen that all of the samples of the present invention have high sensitivity and are excellent in sharpness and granularity.

[0108]

According to the present invention, it is possible to provide a screen which provides an image with improved sensitivity, sharpness and granularity.

Claims (2)

[Claims] 1. A radiation intensifying screen in which a phosphor layer and a protective layer are arranged in this order on a support, wherein the phosphor constituting the phosphor layer is a phosphor represented by the following general formula (1). And a phosphor represented by the following general formula (2). General formula (1) Ln _1-ax M ¹ _a Ta _1-p Nb _p O _{4-a / 2} : xA ³⁺ [wherein, Ln is at least one rare earth element selected from Y, Lu, Gd and La. Yes, M ¹ is Be, Mg, C
a, at least one divalent metal element selected from Sr, Ba, Zn, and Cd; A is at least one rare earth element selected from Tm, Gd, and Tb; (however, when Ln includes Gd, A does not include Gd). 0 ≦ a ≦
1, 0 ≦ x ≦ 0.1, a + x ≦ 1, and 0 ≦ p ≦ 1. General formula (2) Ba _1-by M ² _b FCl _1-z X _z : yEu ²⁺ (wherein, M ² is at least one divalent metal element selected from Sr and Ca, and X is Br, I At least one halogen atom selected from the group consisting of 0 ≦ b ≦ 1, 0.001
≦ y ≦ 0.2, b + y ≦ 1, and 0 ≦ z ≦ 0.5). 2. In a radiation intensifying screen in which a plurality of phosphor layers and a protective layer sequentially laminated on a support are arranged in this order, the phosphor constituting each phosphor layer is represented by the general formula (1). Or a phosphor represented by the general formula (2), wherein phosphor types in adjacent phosphor layers are different from each other.