JPS61120886A - Radiation image converting method and radiation image converting panel for said method - Google Patents

Abstract

PURPOSE:To improve sensitivity in a radiation image converting method, by allowing a radiation passed through a material to be absorbed by a phosphor, irradiating the phosphor with electromagnetic waves and detecting radiation energy stored therein as fluorescence. CONSTITUTION:A radiation passed through a material or radiated from a mate rial to be detected is allowed to be absorbed by a bivalent europium-activated composite halide phosphor of the formula. The phosphor is irradiated with electromagnetic waves in the wavelength region of 450-1,000nm to release radiation energy stored in the phosphor as fluorescence, and the released fluores cence is detected. In the formula, MII is Ba, Sr, Ca; X, X' are different groups and each is Cl, Br, I; 0.1<=a<=10.0; 0<b<=10<-3>; 0<x<=0.2. Pref. the phosphor is incorporated in a radiation image converting panel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a radiation image conversion method and a radiation image conversion panel used in the method. More specifically, the present invention relates to a radiation image conversion method using a photostimulable divalent europium-activated composite halide phosphor, and a radiation image conversion panel used in the method.

[Background of the Invention] Conventionally, as a method for obtaining radiation images as images, so-called radiography uses a combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen. law is being used. ] As one of the methods to replace the conventional radiographic method, a radiation image conversion method using a stimulable phosphor is known, for example, as described in JP-A-55-12145. ing.

In this method, radiation transmitted through the subject or radiation emitted from the subject is absorbed into a stimulable phosphor, and then the phosphor is exposed to electromagnetic waves (excitation light) such as visible light or infrared rays in a time-series manner. By exciting the phosphor, the radiation energy stored in the phosphor is emitted as fluorescence (stimulated luminescence), this fluorescence is read photoelectrically to obtain an electrical signal, and this electrical signal is converted into an image. .

The radiation image conversion method has the advantage that it is possible to obtain an X-ray image with a rich amount of information with a much lower exposure dose than when conventional radiography is used. Therefore, this radiation image conversion method has a very high utility value especially in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

Conventionally, a divalent europium-activated alkaline earth metal fluoride halide phosphor (M"FX: Eu&, however, MI
[is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, and X is a halogen other than fluorine] has been proposed. This phosphor is
After absorbing radiation such as radiation, it emits light in the near-ultraviolet region (stimulated luminescence) when irradiated with electromagnetic waves in the visible light to infrared region.

As mentioned above, the radiation image conversion method utilizes the photostimulability of the phosphor, but the stimulable phosphor itself, other than this divalent europium-activated alkaline earth metal fluoride halide phosphor, does not have much effect. unknown.

The applicant has already filed a patent application for a radiation image conversion method and a radiation image conversion panel using a novel divalent europium-activated alkaline earth metal halide phosphor represented by the following compositional formula (Japanese Patent Application No. No. 193162).

Compositional formula: MIIX2eaMIIX'2:xEu2+
(However, MN is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
and Xo is at least one halogen selected from the group consisting of Cl, Br and I, and
and a is a numerical value in the range of 0.1≦a≦10.0, and X is a numerical value in the range of 0<x≦0.2). From its X-ray diffraction pattern, the phosphor has the above-mentioned M "F
X: It has been found that E u 2+ phosphor is a different type of phosphor with a different crystal structure, and it is
450 to 11,000 after irradiating with radiation such as electron beam
When excited with electromagnetic waves in the wavelength range of n, it exhibits near-ultraviolet to blue light emission (stimulated luminescence) with an emission maximum around 405 nm.

- The radiation image conversion method using a radiation image conversion panel made of a stimulable phosphor is a very advantageous image forming method as described in -■-, but even in this method, the sensitivity is as high as possible. It is desirable that the Generally, the sensitivity of a radiation image storage panel to radiation increases as the stimulated luminance of the phosphor used therein increases. Therefore, it is desired that the stimulable phosphor used in the panel has as high a stimulable luminance as possible.

[Summary of the Invention] An object of the present invention is to provide a radiation image conversion method with improved sensitivity and a radiation image conversion panel used in the method.

In order to achieve the above object, the present inventor conducted various studies on the new divalent europium-activated alkaline earth metal halide phosphor. As a result, it was discovered that a phosphor obtained by adding a specific amount of tin halide to the phosphor exhibits high-intensity stimulated luminescence, leading to the present invention.

That is, in the radiation image conversion method of the present invention, after the radiation transmitted through the subject or emitted from the subject is absorbed by the divalent europium-activated composite halide phosphor represented by the following compositional formula (I), 450~ for this phosphor
It is characterized in that by irradiating electromagnetic waves in a wavelength range of 1000 nm, the radiation energy stored in the phosphor is emitted as fluorescence, and this fluorescence is detected.

Composition formula (I): MIIX2*aMx' 2 ・bSnX" 2 :X
E u 2') ... (I) (However, Mm is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr and Ca;
o is at least one kind of halogen selected from the group consisting of CJL, Br and I, and X#X'
And; Xo.

is at least one halogen selected from the group consisting of F, Cl, Br and I; and a is 0.1≦a≦
10.0, b is a numerical value in the range of o<b≦10-3, and X is a numerical value in the range of O<x≦0.2). The conversion panel is a radiation image conversion panel substantially composed of a support and a stimulable phosphor layer provided on the support, wherein the stimulable phosphor layer has the above composition. 4! Contains a divalent europium-activated composite halide phosphor represented by formula (I)! be a sign.

The present invention enables the phosphor to be irradiated with radiation such as X-rays by adding specific tin halide (tin halide) to the novel divalent europium-activated alkaline earth metal halide phosphor. After that 450-11000
This was completed based on the new finding that the luminance of stimulated luminescence increases significantly when excited by electromagnetic waves in the wavelength region of n.

Therefore, by using the divalent europium-activated composite halide phosphor represented by the composition formula (I) shown in -1-, the sensitivity of the radiation image conversion method can be improved. Furthermore, the radiation image conversion panel of the present invention made of the L phosphor exhibits significantly improved sensitivity.

[Structure of the Invention] The divalent europium-activated composite halide phosphor used in the present invention has a composition formula (I): MIIX2 *'aMI
IX' 2 e bS nX” 2 :xEu2+
River (I) (However, MIIF is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X' are both at least one kind selected from the group consisting of CM, Br, and I. is a halogen, and X#X' is at least one kind of halogen selected from the group consisting of F, Cl, Br, and ■;
and a is a numerical value in the range of 0.1≦a≦10, o;
b is a numerical value in the range o<b≦10-3, and X is 0<x
It is a numerical value in the range of ≦0.2).

■-In the phosphor represented by the above formula (I), from the point of view of #exhaustive luminance, tin halide (Snx”2)cy)
The b value representing the quantity is preferably in the range lO'≦b≦5X10-4, and x'' is preferably F. Further, the a value representing the ratio of MIIX2 and MIIX'2 in composition formula (I) is preferably in the range of 0.25≦6.0, more preferably in the range of 0.5≦a≦2.0. The X value representing the activation amount of europium is 10'≦
It is preferable that X≦10 −1.

-1- BaCu2 *BaBr2 * bSnF2, which is an example of a phosphor represented by the composition formula (I): 0.00
In the 1Eu2+ phosphor, the b value representing the amount of tin fluoride in the phosphor and the stimulated luminance have a relationship as shown in FIG.

Figure 81 shows BaCjL2 eBaBr2 * bSnF
2: b value and stimulated luminance of 0.001E u” phosphor [stimulated luminance when excited with semiconductor laser light (780 nm) after irradiation with 80 KVp X-rays]
It is a graph showing the relationship between As is clear from Fig. 1, BaCfL2 whose b value is in the range of o<b≦10−3
*BaBr211bSnF2:0.001Eu2+ phosphor exhibits stimulated luminescence with higher brightness than phosphor to which no tin fluoride is added (b=o). It is based on this fact that the b value in the divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention is defined in the range of o<b≦10-4. Furthermore, from FIG. 1, it is clear that particularly phosphors having a b value in the range of 10-5≦b≦5X10-4 exhibit extremely high-intensity stimulated luminescence.

ft, O, M", X, X', X" 7 It has been confirmed that the relationship has the same tendency as in Figure 1.

Incidentally, the stimulated emission spectrum and the cape-stimulated excitation spectrum of the divalent europium-activated composite halide phosphor represented by the above compositional formula (I) are as described in the above-mentioned Japanese Patent Application No. 58-19.
It is almost the same as the stimulated emission spectrum and stimulated excitation spectrum of the divalent europium-activated alkaline earth metal halide phosphor described in No. 3162. The wavelength range of the photostimulated excitation spectrum is 450 to 1
1000 nm, and therefore, in the radiation image conversion method of the present invention using this phosphor, the wavelength of the excitation light can be changed appropriately, that is, the excitation light source can be appropriately selected depending on the purpose. . For example, since the stimulated excitation spectrum of the above-mentioned phosphor extends to about 11,000 nm, a compact semiconductor laser (having an emission wavelength in the infrared region) with low driving power can be used as a stimulated light source. Therefore, it is possible to downsize the apparatus for carrying out the radiation image conversion method. In addition, from the point of view of the brightness of stimulated luminescence and the wavelength separation from the emitted light, the excitation light in the radiation image conversion method of the present invention is 500 to 85
Preferably, the electromagnetic wave is in a wavelength range of 0 nm.

The divalent europium-activated composite halide phosphor represented by the above compositional formula (I) can be manufactured, for example, by the manufacturing method described below.

First, as raw materials for the phosphor, 1) at least two alkaline earth metal halides selected from the group consisting of barium halide, calcium halide, and strontium halide, 2) tin halide, and 3) halide, oxide. At least one compound selected from the group consisting of compounds of europium such as compounds, nitrates, and sulfates is prepared. In some cases, ammonium halide or the like may also be used as a flux.

When producing a phosphor, first, using the alkaline earth metal halide (1) above, the tin halide (2), and the europium compound (3) above, the composition formula (■
): MIIX2 ・aMIIX' 2 @bSnX” 2
:xEu...(n) (However, the definitions of M", X, X', x°", a, b, and X are the same as above).

The above mixture operation is carried out, for example, in the form of a suspension. Then, by removing water from the suspension of this phosphor raw material mixture, a solid dry mixture is obtained. This water removal operation is preferably carried out at room temperature or at a not very high temperature (for example, 200° C. or lower) by drying under reduced pressure, vacuum drying, or both. Of course, the mixing operation is not limited to the above method.

Note that the tin halide mentioned in 2) above may be added to this dry mixture without being added at the time of weighing and mixing the phosphor raw materials.

Next, the obtained dry mixture is finely pulverized, and the pulverized product is filled into a heat-resistant container such as a quartz port or an alumina crucible, and fired in an electric furnace. The firing temperature is 4
A temperature in the range of 00 to 1300° C. is appropriate, and the firing time varies depending on the amount of the phosphor raw material mixture filled and the firing temperature, but in general, 0.5 to 6 hours is appropriate. As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere, or a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas or a carbon dioxide atmosphere containing -carbon oxide is used. When the europium compound used contains trivalent europium, the trivalent europium is reduced to divalent europium during the firing process.

Note that a method may also be used in which the phosphor raw material mixture is once fired under the above firing conditions, and then the fired product is left to cool, pulverized, and then re-fired (secondary firing). Re-firing is carried out under the above neutral atmosphere or weakly reducing atmosphere at a temperature of 400 to 80
The firing is carried out at a firing temperature of 0° C. for 0.5 to 12 hours.

The powdered phosphor used in the present invention is obtained by the above baking. Regarding the obtained powdered phosphor,
If necessary, various general operations in the production of phosphors such as washing, drying, sieving, etc. may be further performed.

By utilizing the manufacturing method described below, the divalent europium-activated composite halide phosphor represented by the above compositional formula (I) can be obtained.

In the radiation image conversion method of the present invention, the compositional formula (I
) is preferably used in the form of a radiation image storage panel (also referred to as a stimulable phosphor sheet) containing the divalent europium-activated composite halide phosphor.

The basic structure of a radiation image storage panel is a support and at least one stimulable phosphor layer provided on one side of the support. The stimulable phosphor layer consists of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state. Note that a transparent protective film is generally provided on the surface of the phosphor layer opposite to the support (the surface not facing the support) to protect the phosphor layer from chemical deterioration or Protects from physical impact.

That is, the radiation image conversion method of the present invention is preferably carried out using a radiation image conversion panel having a phosphor layer made of a divalent europium-activated composite halide phosphor represented by the above-mentioned compositional formula (I).

In the radiation image conversion method of the present invention using the stimulable phosphor represented by the composition formula (I) in the form of a radiation image conversion panel, the radiation image is transmitted through the object. Alternatively, the radiation emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and the radiation image of the subject or subject appears on the radiation image conversion panel as an image of accumulated radiation energy. Formed S. This accumulated image is 450 to 110
By exciting it with electromagnetic waves (excitation light) in the 00n wavelength range, it can be emitted as stimulated luminescence (fluorescence),
By photoelectrically reading this stimulated luminescence and converting it into an electrical signal, it becomes possible to image the accumulation of radiation energy.

The radiation image conversion method of the present invention will be specifically explained using the schematic diagram shown in FIG. 2, taking as an example an embodiment in which a stimulable phosphor represented by the composition formula (I) is used in the form of a radiation image conversion panel. do.

In FIG. 2, ll is a radiation generating device such as an X-ray, and 1
2 is a subject, 13- is a radiation image conversion panel containing a stimulable phosphor represented by the above compositional formula (I), and 14 is a radiation image conversion panel for emitting an image of accumulated radiation energy on the radiation image conversion panel 13 as fluorescence. A light source as an excitation source, 15 a photoelectric conversion device that detects fluorescence emitted from the radiation image conversion panel 13, 16 a device that reproduces the photoelectric conversion signal detected by the photoelectric conversion device 15 as an image, and 17 a reproduced image. A device for displaying an image, and a filter 18 that does not allow the reflected light from the light source 14 to pass through, but only allows the fluorescence emitted from the radiation image conversion panel 13 to pass through.

Although FIG. 2 shows an example of obtaining a radiographic image of a subject, the subject 12 itself emits radiation (
In this specification, this is referred to as a subject), there is no particular need to install the radiation generating device 11 described above. Further, the photoelectric conversion device 15 to the image display device 17 can be replaced with other suitable devices that can reproduce information emitted as fluorescence from the radiation image conversion panel 13 as an image in some form.

As shown in FIG. 2, when a subject 12 is irradiated with radiation such as X-rays from the radiation generating device 11, the radiation passes through the subject 12 in proportion to the radiation transmittance of each part of the subject 12. The radiation that has passed through the subject 12 then enters the radiation image conversion panel 13 and is absorbed by the phosphor layer of the radiation image conversion panel 13. That is, a radiation energy accumulation image (a kind of latent image) corresponding to a radiation transmission image is formed on the radiation image conversion panel 13.

Next, using the light source 14 on the radiation image conversion panel 13,
When irradiated with electromagnetic waves in the wavelength range of 0 to 1000 nm, the accumulated radiation energy image formed on the radiation image conversion panel 13 is emitted as fluorescence. The emitted fluorescence is proportional to the intensity of the radiation energy absorbed by the phosphor layer of the radiation image conversion panel 13. This optical signal composed of the intensity of fluorescence is converted into an electrical signal by a photoelectric conversion device 15 such as a photomultiplier tube, and the image reproducing device 1
6, the image is reproduced as an image, and the image display device 17 displays this image.

The operation of reading out the image information accumulated in a radiation image conversion panel as fluorescence is generally performed by scanning the panel in time series with a laser beam, and by photoelectron amplification of the fluorescence emitted from the panel through an appropriate light condenser. This is done by detecting with a photodetector such as a multiplier tube and obtaining time-series electrical signals.

In order to obtain an image with better observation and interpretation performance, this readout may consist of a pre-reading operation by irradiating low-energy excitation light and a main-reading operation by irradiating high-energy excitation light (JP-A-58 (Refer to Publication No.-67240). By performing this pre-read operation, there is an advantage that the read conditions for the main read operation can be suitably set.

Furthermore, solid photoelectric conversion elements such as photoconductors and photodiodes can also be used as photoelectric conversion devices (Japanese Patent Application No. 58-86226, Japanese Patent Application No. 58-862).
No. 27, Japanese Patent Application No. 1983-219313 and Japanese Patent Application No. 1983
Specifications of No.-219314 and JP-A-58-12
(See Publication No. 1874). In this case, a large number of solid-state photoelectric conversion elements may be configured to cover the entire surface of the panel, and may be integrated with the panel, or may be arranged in close proximity to the panel. Further, the photoelectric conversion device may be a line sensor in which a plurality of photoelectric conversion elements are connected in a linear manner, or may be composed of one solid-state photoelectric conversion element corresponding to one pixel.

In addition to a point light source such as a laser, the light source in the case of -1- may be a line light source such as an array of light emitting diodes (LEDs), semiconductor lasers, etc. arranged in a row. By performing readout using such a device, it is possible to prevent loss of fluorescence emitted from the panel, and at the same time, increase the solid angle of light reception and increase the S/N ratio. Further, since the obtained electrical signal is converted into a time series by electrical processing of a photodetector rather than by time-series irradiation of excitation light, it is possible to increase the readout speed.

The radiation image conversion panel from which the image information has been read is erased by irradiating it with light in the wavelength range of the excitation light of the phosphor or by heating it. It is preferable to do so (Japanese Patent Application Laid-open No. 11392/1983 and
(Refer to Publication No.-12599). By performing this erasing operation, it is possible to prevent noise from occurring due to afterimages when the panel is used next time. Furthermore, by performing the erasing operation twice, once after reading and immediately before the next use, it is possible to prevent the generation of noise due to natural radioactivity and perform the erasing more efficiently (Japanese Patent Laid-Open No. 57-116
(See Publication No. 300).

In the radiation image conversion method of the present invention, the radiation used to obtain a radiation transmission image of the subject is capable of exhibiting stimulated luminescence when the phosphor is excited by the electromagnetic waves after being irradiated with this radiation. Any radiation may be used as long as it is suitable for the radiation, for example, commonly known radiation such as X-rays, electron beams, and ultraviolet rays can be used. Further, when obtaining a radiation image of the subject, the radiation directly emitted from the subject may be any radiation that is similarly absorbed by the phosphor and serves as an energy source for stimulated luminescence. Examples include radiation such as gamma rays, alpha rays, beta rays, and neutron radiation.

As a light source of excitation light for exciting the phosphor that has absorbed radiation from the subject or the subject, 450~looo
In addition to light sources that emit light with a band spectral distribution in the onm wavelength region, for example, Ar ion laser-1K
Lasers such as r-ion lasers, He-Ne lasers, ruby lasers, semiconductor lasers, glass lasers, YAG lasers, dye lasers, and light sources such as light emitting diodes can also be used. Among these, lasers can irradiate a radiation image conversion panel with a laser beam with high energy density per unit area.
It is preferred as an excitation light source used in the present invention. Among them, preferred lasers are He-Ne laser and Ar ion laser in terms of stability and output.
and a Kr ion laser. In addition, semiconductor lasers are preferable as excitation light sources because they are compact, require low driving power, and can be directly modulated, making it easy to stabilize laser output.

The light source used for erasing may be one that emits light in the excitation wavelength range of the stimulable phosphor; examples include tungsten lamps, fluorescent lamps, halogen lamps, and high-pressure sodium lamps. can.

The radiation image conversion method of the present invention includes: a storage section that absorbs and stores radiation energy in a stimulable phosphor; a photodetection (readout) section that irradiates the phosphor with excitation light and emits the radiation energy as fluorescence; It can also be applied to a built-in type radiation image conversion device in which an erasing section for emitting energy remaining in the phosphor is built into one device (Japanese Patent Application No. 57-84436 and Japanese Patent Application No. 58-6
6730 specification). By using such a built-in device, the radiation image conversion panel (or the recording material containing the stimulable phosphor) can be reused and a stable and homogeneous image can be obtained. can.

Further, by using a built-in type, the device can be made smaller and lighter, and its installation and movement become easier. Furthermore, by mounting this device on a mobile vehicle, it becomes possible to carry out circular radiography.

Next, a radiation image conversion panel used in the radiation image conversion method of the present invention will be explained.

As described above, this radiation image storage panel substantially contains a support and a divalent europium-activated composite halide phosphor provided on the support and represented by the composition formula (I) in a dispersed state. and a stimulable phosphor layer comprising a supporting binder. The stimulable phosphor layer can be formed on the support, for example, by the following method.

Examples of binders 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, niatrocellulose, ethylcellulose, bee chloride + 1 densine/vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride - Binders typified by synthetic polymeric substances such as vinyl acetate copolymers, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, and linear polyesters. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth)acrylates, mixtures of nitrocellulose and linear polyesters, and mixtures of nitrocellulose and polyalkyl (meth)acrylates. It is.

First, the above-mentioned particulate stimulable phosphor and a binder are added to a suitable solvent and thoroughly mixed to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution.

Examples of solvents for preparing coating solutions include lower alcohols such as methanol, ethanol, n-propanol, and n-phthanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, and methyl isobutyl ketone. 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, and ethylene glycol monomethyl ether; and mixtures thereof.

The mixing ratio of the binder and the stimulable phosphor in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, etc., but generally the mixing ratio of the binder and the stimulable phosphor is 1. :1 to 1:100 (weight ratio), and particularly preferably l:8 to 1:40 (weight ratio).

The coating solution contains a dispersant to improve the dispersibility of the phosphor in the coating solution, and a dispersant to improve the bonding force between the binder and the phosphor in the phosphor layer after formation. Various additives, such as plasticizers, may be mixed to make the material more durable. Examples of dispersants used for such purposes include:
Examples include phthalic acid, stearic acid, caproic acid, and lipophilic surfactants. Examples of plasticizers include phosphate esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalate esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate, butyl phthalyl glycolate, etc. and polyesters of polyethylene glycol and aliphatic dibasic acids, such as polyesters of triethylene glycol and adipic acid and polyesters of diethylene glycol and succinic acid.

The coating solution containing the phosphor and binder prepared as described above is then uniformly applied to the surface of the support to form a coating film of the coating solution.

This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc.

As a support, an intensifying screen (
The material can be arbitrarily selected from various materials used as supports for (or intensifying screens) or conventional materials known as supports for radiation image storage panels. Examples of such materials include films of plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, ordinary paper, baryta, etc. Examples include paper, resin-coated paper, pigment paper containing pigments such as titanium dioxide, and paper sized with polyvinyl alcohol.

However, in consideration of the characteristics and handling of the radiation image storage panel as an information recording material, a particularly preferred 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 radiation image conversion panel, and the latter is a support suitable for a high sensitivity type radiation image conversion panel.

In known radiation image conversion panels, a 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 (g sharpness, granularity) of the radiation image conversion panel. A polymeric substance such as gelatin is coated on the surface of the support on the side to be coated to form an adhesion imparting layer, or a light reflective layer made of a light reflective substance such as titanium dioxide, or a light absorbing substance such as carbon black. It is known to provide a light absorption layer or the like. The support used in the present invention can also be provided with these various layers, and their configurations can be arbitrarily selected depending on the purpose, use, etc. of the desired radiation image storage panel.

Furthermore, as disclosed in JP-A-58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side) When an adhesion-imparting layer, a light-reflecting layer, a light-absorbing layer, etc. are provided, minute irregularities may be formed on the surface (meaning the surface thereof).

After forming a coating film on the support as described above, the coating is dried to complete the formation of the stimulable phosphor layer on the support. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, the mixing ratio of the binder and the phosphor, and is usually 20 gm to 1 mm. However, the thickness of this layer is preferably between 50 and 500 gm.

In addition, the stimulable phosphor layer does not necessarily have to be formed by directly applying a coating solution onto the support as described above, but can be formed by separately applying it to a sheet such as a glass plate, metal plate, plastic sheet, etc. After forming a phosphor layer by applying a liquid and drying it, this is pressed onto a support, or
Alternatively, the support and the phosphor layer may be bonded together using an adhesive or the like.

Although only one stimulable phosphor layer may be used, two or more layers may be stacked. In the case of multiple layers, at least one of the layers should contain the divalent europium-activated composite halide phosphor of composition formula (I), and the luminous efficiency against radiation increases sequentially toward the surface of the panel. A structure in which a plurality of phosphor layers are stacked may be used. Moreover, in both the case of a single layer and a multilayer, a known stimulable phosphor can be used in combination with the phosphor described in -.

Examples of such known stimulable phosphors include, in addition to the above-mentioned phosphors, ZnS:Cu, Pb, Bab@xA 1203, which is described in JP-A-55-12i42.
:Eu (however, 0.8≦x≦10), and M
”0-xsi02:A (However, MII is Mg, C
a, Sr, Zn, Cd, or Ba, A is Ce,
Tb, Eu, Tm, Pb, Tl, Bi, or Mn, and X is 0.5≦X≦2.5), as described in JP-A-55-12143 (
al-x-y, Mgx, Cay) FX
:aEu2') (However, X is at least one of 0 sentence and Br, and X and y are 0<x+y≦0
．． 6, and xy+o, and a is 10-6≦a≦5
X 10-2), and JP-A-55-1214
LnOX: xA (however, L
n is at least − of La, Y, Gd, and Lu;
t, X is at least of CJI and Br - t, A
is at least − of Ce and Tb, and X is O<x<O, l).

In a normal radiation image storage panel, as mentioned above, a transparent protective film is provided on the surface of the phosphor layer on the side opposite to the side that contacts the support to physically and chemically protect the phosphor layer. It is being Such a transparent protective film is preferably provided also in the radiation image conversion panel of the present invention.

The transparent protective film may be made of, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a synthetic polymer material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copolymer. It can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a transparent polymeric substance in an appropriate solvent. Alternatively, it can also be formed by a method such as adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide, etc. to the surface of the phosphor layer using a suitable adhesive. The thickness of the transparent protective film formed in this way is approximately 0.1 to 2.
It is desirable to set it to 0gm.

In addition, JP-A-55-163500, JP-A-57-
As described in Japanese Patent No. 96300 and the like, the radiation image conversion panel of the present invention may be colored with a colorant, and the sharpness of the image obtained can be improved by coloring. Further, as described in Japanese Patent Application Laid-Open No. 55-146447, the radiation image conversion panel of the present invention may have white powder dispersed in its phosphor layer for the same purpose.

Examples and comparative examples of the present invention are described below. However, each of these does not limit the present invention.

[Example 1] Barium bromide (BaBr2) (7) aqueous solution (1,55X
10"mol/g) 192, 7g, barium chloride (BaCjL2)cy) aqueous solution (1,18X 10"
mol/g) 253.

5g, and an aqueous solution of europium bromide (EuBr3) (2,841X 10''-'mol/ml) 2,1
1 ml was mixed. This aqueous solution was dried under reduced pressure at 60°C for 3 hours, and then further vacuum dried at 150'0 for 3 hours.

Next, 10 g of the obtained phosphor raw material mixture and tin fluoride (S
After thoroughly mixing 0.6 mg of nF2), it was filled into an alumina crucible, and the mixture was placed in a high-temperature electric furnace for firing. The calcination was carried out in a carbon dioxide atmosphere containing -carbon oxide.
The test was carried out at a temperature of 50° C. for 1.5 hours. After the firing was completed, the fired product was taken out of the furnace and cooled. In this way, divalent europium-activated composite halide phosphor (BaCJL2 eBaBr2 eO,o001snF
2:0.0oIE u”) Omata.

An example? ] In Example 1, a divalent europium-activated composite halide phosphor (BaCM.*BaBr 240.00005 S
n F z :0.001E u2+) was obtained.

[Example 3] Divalent europium-activated composite halide phosphor (BaCu2・BaBr2 ・0.001S
n F 2 :0.001E u2+) was obtained.

[Comparative Example 1] In Example 1, divalent europium-activated barium chloride bromide phosphor (BaCJlz・BaBr2: 0.001E
u2+) was obtained.

Next, each of the phosphors obtained in Examples 1 to 3 and Comparative Example 1 was irradiated with X-rays at a tube voltage of 80 KVp and then excited with semiconductor laser light (780 nm), and the stimulated luminance was measured. The results are summarized in Figure 1.

Figure 1 shows BaCM2 @BaBr2 a bSnF
2 :0.001E u 2+ FIG. 2 is a graph showing the relationship between the content of tin fluoride (b value) and stimulated luminance in a phosphor.

As is clear from FIG. 1, B a used in the present invention
CJl 2 II B a B r 2 * b S
nF2:0.001Eu2+ phosphor has a stimulated luminance of −1 when the b value is in the range of o<b≦t o−3. In particular, if the b value is 10-5≦b≦5
Phosphors in the O-4 range exhibit high brightness stimulated luminescence.

[Example 41 Using each of the phosphors obtained in Examples 1 to 3 and Comparative Example 1, a radiation image conversion panel was manufactured as follows.

A dispersion liquid containing a phosphor in a dispersed state by adding methyl ethyl ketone to a mixture of a powdered bivalent europium-activated composite halide phosphor and a linear polyester resin, and further adding nitrocellulose with a degree of nitrification of 11.5%. was prepared. Next, tricresyl phosphate, n-butanol, and methyl ethyl ketone were added to this dispersion, and the mixture was thoroughly stirred and mixed using a propeller mixer to ensure that the phosphor was uniformly dispersed and that the mixing ratio between the binder and the phosphor was adjusted. 1:Lo
A coating solution with a viscosity of 25 to 35 PS (25°C) was prepared. Next, the coating solution was placed on a titanium dioxide-mixed polyethylene terephthalate sheet (support, thickness: 25011.m) placed horizontally on a glass plate. was applied evenly 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 layer thickness of 250
A phosphor layer of pLm was formed.

Then, by placing and adhering a transparent film of polyethylene terephthalate (thickness: 12 JLm, polyester adhesive has been treated with H4) on top of this phosphor layer with the adhesive layer side facing down, a transparent protective film is formed. was formed.

In this manner, various radiation image conversion panels each comprised of a support, a phosphor layer, and a transparent protective film were manufactured.

[Example 5] In Example 1, tin chloride (S n
Divalent europium-activated composite halide phosphor (BaCu
2eBaBr2*o,ooolsnCl2:0.
001E u 2+) was obtained.

Next, the obtained phosphor was subjected to the same treatment as in Example 4 to produce various radiation image conversion panels each comprised of a support, a phosphor layer, and a transparent protective film.

[Example 6] In Example 1, tin bromide (SnB) was used instead of tin fluoride.
r2) Divalent europium-activated composite halide phosphor (BaCl2eBaBr2*0
．． 0001snBr2:0.001Eu2+).

Next, the obtained phosphor was subjected to the same treatment as in Example 4 to produce various radiation image conversion panels each comprised of a support, a phosphor layer, and a transparent protective film.

Next, after irradiating each radiation image conversion panel obtained in Examples 4 to 6 with X-rays with a tube voltage of 80 KVp, the sensitivity (stimulated luminescence brightness) of the panel when excited with semiconductor laser light (780 nm) was measured. It was measured. The results are shown in Table 1.

1. Lower shear Table 1 Relative sensitivity BaCl2 @ BaBr2 @ 0.0001 SnF
2: Panel using 0.001Eu2+phosphor 1
21BaCl2* BaBr2 m 0.00005S
nF2: Panel using 0.0OIEu2+phosphor
119BaCl2e BaBr2 *O,0OIS
nF2: 0, (panel using 101Eu2+ phosphor
101BaCl2* BaBr2* Q, 0001
SnCI2: Panel using 0.001Eu2+phosphor 103BaCl2* BaBr2 e O,00
01SnBr2: 0.001Eu2+panel using phosphor 103BaCl2e BaBr2: 0.0
Panel using QIEu2+ phosphor 10
0

[Brief explanation of the drawing]

FIG. 1 shows B, which is a specific example of the phosphor used in the present invention.
aCl12 ・BaBr2 ・bSnF2: 0.001
It is a graph showing the relationship between b value and stimulated luminescence luminance in E u 2+ phosphor. FIG. 2 is a schematic diagram illustrating the radiation image conversion method of the present invention. ll: Radiation generator, 12: Subject, 13: Radiation image conversion panel, 14: Light source, 15: Photoelectric conversion device, 16:
Image reproducing device, 17: Image display device, 18: Filter Patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Yasuo Yanagawa Figure 1-fL Figure 2 The "Detailed description of the invention" column of the specification is as follows: I will correct it accordingly. Hand Thread Sales Assistant - iTg Book December 1980 1411 1988 Patent Application No. 240455 2, Title of Invention Radiation Image Conversion Method and Emission Radiation Image Conversion Panel 3 Used in the Method, Person Who Makes Amendment Case and Relationship Patent applicant name (520) Fuji Photo Film Co., Ltd. 4, agent address 8 Miya Yotsuya Building, 2-14 Yotsuya, Shinjuku-ku, Tokyo
Floor 6: Number of inventions increased by amendment None 7: Subject of amendment “Detailed description of the invention” column of the specification ・(
1) +3 page 6th line 10.25≦6, Oj is Ir
Correct as O, 25≦a≦6, Oj. (2) Page 3B, line 8, ``2, 11m intersection j to Ii'1
．． Corrected to 06m look J. (3) Fo, 6mgj on page 38, line 13 is “0.3
Correct as mgj. (4) Fo on page 38, line 3 to line 4 of the same page, 3 mg
Correct j to 110.15 mgj. (5) From page 39, line 10 to page 111, ff6.2
Correct mgj to 3.1mgj. (6) Correct lro, 9mgj to 1'0.4 on page 42, line 9.
Corrected to 4mgj. (7) 0.1 mgJ on page 42, line 20 is l'0.55
Correct as mgj. ”−

Claims (16)

[Claims] 1. After the radiation transmitted through the subject or emitted from the subject is absorbed by the divalent europium-activated composite halide phosphor represented by the composition formula (I) below,
A radiation image conversion method characterized in that the phosphor is irradiated with electromagnetic waves in a wavelength range of 450 to 1000 nm to cause the radiation energy stored in the phosphor to be emitted as fluorescence, and the fluorescence is detected. Composition formula (I): M^IIIX_2・a_M^IIIX'_2・b_SnX"
_2:x_Eu^2^+ ...(I) (However, M^III is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X' are both Cl, At least one halogen selected from the group consisting of Br and I, and X≠X';X'' is F, Cl, Br and
I is at least one halogen selected from the group consisting of ,
x is a numerical value in the range of 0<x≦0.2) 2. b in composition formula (I) is 10^-^5≦b≦
2. The radiation image conversion method according to claim 1, wherein the value is in the range of 5×10^-^4. 3. 2. The radiation image conversion method according to claim 1, wherein X'' in compositional formula (I) is F. 4. a in the compositional formula (I) is 0.25≦a≦6.
2. The radiation image conversion method according to claim 1, wherein the value is in the range of 0. 5. 2. The radiation image conversion method according to claim 1, wherein M^III in the compositional formula (I) is Ba. 6. 2. The radiation image conversion method according to claim 1, wherein X and X' in compositional formula (I) are each Cl or Br. 7. x in compositional formula (I) is 10^-^5≦x≦1
2. The radiation image conversion method according to claim 1, wherein the value is in the range of 0^-^1. 8. The radiation image conversion method according to claim 1, wherein the electromagnetic wave is an electromagnetic wave in a wavelength range of 500 to 850 nm. 9. 2. The radiation image conversion method according to claim 1, wherein the electromagnetic wave is a laser beam. 10. In a radiation image conversion panel substantially composed of a support and a stimulable phosphor layer provided on the support, the stimulable phosphor layer is composed of two compounds represented by the following compositional formula (I). A radiation image conversion panel comprising a valent europium-activated composite halide phosphor. Composition formula (I): M^IIX_2・aM^IIX'_2・bSnX"_2
:xEu^2^+...(I) (However, M^II is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and x' are both Cl, Br and at least one halogen selected from the group consisting of I, and X≠X';X'' is at least one halogen selected from the group consisting of F, CL, Br, and I;
and a is a numerical value in the range of 0.1≦a≦10.0,
b is a numerical value in the range of 0<b≦10^-^3, and x is 0
<A numerical value in the range of x≦0.2) 11. b in compositional formula (I) is 10^-^5≦b≦
11. The radiation image conversion panel according to claim 10, wherein the value is in the range of 5×10^-^4. 12. 11. The radiation image storage panel according to claim 10, wherein x'' in compositional formula (I) is F. 13. a in compositional formula (I) is 0.25≦a≦6.
11. The radiation image conversion panel according to claim 10, wherein the value is in the range of 0. 14. 11. The radiation image conversion panel according to claim 10, wherein M^II in compositional formula (I) is Ba. 15. 11. The radiation image storage panel according to claim 10, wherein x and x' in compositional formula (I) are each Cl or Br. 16. x in compositional formula (I) is 10^-^5≦x≦
11. The radiation image conversion panel according to claim 10, wherein the value is in the range of 10^-^1.