JPS60228999A - Method of converting radiation image and radiation image converting panel used for said method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 is based on a detailed description of the invention.

This invention relates to a radiation image conversion method using an activated valent europium-activated alkaline earth metal halide phosphor, and a radiation image conversion panel used in the method.

[Background of the Invention] Conventionally, there have been seven ways to obtain radiographic images as images.
A combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen is used. A so-called radiographic method is used. As one of the methods to replace the above-mentioned conventional radiography method, a radiation image conversion method using a stimulable phosphor is known, for example, as described in Japanese Patent Application Laid-Open No. 55-12145 (g, etc.). ing.

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

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

As a stimulable phosphor used in the old radiation image conversion method, divalent europium-activated alkaline earth metal fluoride halokenide phosphor (M"FX: Eu2+, however, M
It has been proposed that 1 is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, and X is 7X rogen other than fluorine. This phosphor is
After absorbing radiation such as X-rays, 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 phosphors, but little is known about the stimulable phosphors themselves other than this divalent europium-activated alkaline earth metal halide phosphor. Not yet.

The applicant has already filed a patent application for a radiation image conversion method and a radiation image conversion panel using a new divalent europium-activated alkaline earth metal/rokenide phosphor represented by the following compositional formula (patent application 58-193162
issue).

Compositional formula: M ” X 2 ・a M ” X ' 2
: , and XsX': and a is 0.1≦
It is a numerical value in the range of a≦10.0, and X is 0<x≦0.2
) The conodivalent europium activated alkaline earth metal halide phosphor is
From the line diffraction pattern, it has been determined that the M"FX・Eu2+ phosphor is a different type of phosphor with a different crystal structure, and after irradiation with radiation such as X-rays, ultraviolet rays, and electron beams, 450 When excited with electromagnetic waves in the wavelength range of ~11,000 nm, it exhibits near-ultraviolet to blue light emission (stimulated luminescence) with an emission maximum around 405 nm.

The radiation image conversion method using the radiation image conversion panel made of the above-mentioned stimulable phosphor is a very advantageous image forming method as described above, and even in this method, the sensitivity must be as high as possible. 1 is desirable. 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 degree of stimulated luminescence 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 above-mentioned novel divalent europium-activated alkaline earth metal halide phosphor. As a result, it was discovered that a phosphor obtained by coactivating the phosphor with a specific amount of boron exhibits high-intensity stimulated luminescence, leading to the present invention.

That is, the radiation image conversion method of the present invention converts radiation transmitted through an object or emitted from an object into divalent europium-activated alkaline earth metal halogen co-activated with boron represented by the following compositional formula (I). After absorption by the compound phosphor, the phosphor is irradiated with electromagnetic waves in the wavelength range of 450 to 1000 nm to release the radiation energy stored in the phosphor as fluorescence, and detect this fluorescence. It is characterized by

Composition formula (1): % formula % (1) (where Mll is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
Both X and X' are at least one kind of haloken selected from the group consisting of C1, Br, and I, and X≠X゛; and a is a numerical value in the range of 0.1≦a≦100. , X is a numerical value in the range of O<x≦0.2, and y is a numerical value in the range of 2 is a radiation image conversion panel substantially composed of a support and a stimulable phosphor layer provided on the support, the stimulable phosphor layer having the above composition formula (I). It is characterized by containing a divalent europium-activated alkaline earth metal halide phosphor co-activated with boron represented by:

In the present invention, the novel divalent europium-activated alkaline earth metal halide phosphor is further co-activated with a specific amount of boron, and after irradiating the phosphor with radiation such as X-rays, This work was completed based on the new knowledge that the luminance of stimulated luminescence is significantly improved when excited by electromagnetic waves in the region.

Therefore, by using the boron-coactivated divalent europium-activated alkaline earth metal halide phosphor represented by the composition formula (I), the sensitivity of the radiation image conversion method can be improved. Furthermore, the radiation image conversion panel of the present invention made of the above-mentioned phosphor exhibits significantly improved sensitivity.

[Structure of the Invention] The divalent europium-activated alkaline earth metal halide phosphor co-activated with boron used in the present invention has the composition formula (1): % formula % () (where yIXl is Ba, Sr and is at least one kind of alkaline earth metal selected from the group consisting of Ca; X and Xo are both 0; at least one halogen selected from the group consisting of Br and I; and a is a numerical value in the range of O1l≦a≦1O00, X is a numerical value in the range of O<x≦0.2, and y is a numerical value in the range of 2X10-'≦y≦2X10-'' ).

In terms of stimulated luminance in the phosphor represented by composition formula (I), the y value representing the amount of boron is 4 X I
It is preferable that the range is O-'≦y≦10-'. Further, the a value representing the ratio of M" 2.0, and the X value representing the activation amount of europium is 10-
It is preferable that the range is '≦X≦10-I.

” B, which is an example of a phosphor represented by the bipedal composition formula (I)
acl2-B aB r2 :0.001Eu”
In the yB phosphor, the y value representing the amount of boron in the phosphor and the stimulated luminance have a relationship as shown in FIG.

Figure 1 shows BaC sentence 2 IIB a B r 2 :
0.001E u2+, y value and stimulated luminance in B phosphor [x of 80KVp! It is a graph showing the relationship between the irradiation of M and the stimulated luminescence brightness when excited with semiconductor laser light (780 nm). As is clear from Fig. 1, the y value is in the range of 2X10-'≦y≦2X10'.
:O,0OIE u'', the VB phosphor exhibits stimulated luminescence with higher brightness than the phosphor without boron (y=0). The y value in this valent europium-activated alkaline earth metal halide phosphor is 2 X 10-'≦y≦2
It is based on this fact that the range of XIO-' is defined. Also, from Fig. 1, especially the y value is 4X10-
It is clear that phosphors in the range '≦y≦10-'' exhibit stimulated luminescence with extremely high brightness.

Furthermore, regarding the boron-coactivated divalent europium-activated alkaline earth metal halide phosphor used in the present invention other than the M-, X, X'', a, and X-configuration,
It has been confirmed that the relationship between the y value and the stimulated luminance is similar to that shown in FIG.

In addition, the divalent europium-activated alkaline earth metal halide phosphor co-activated with boron should be added within a range that does not lose the effect of adding boron (direction of luminance - L). Various additive components may also be added.

The stimulated excitation spectrum of the boron-coactivated divalent europium-activated alkaline earth metal halo saponide phosphor represented by the above compositional formula (I) is as described in the above-mentioned Japanese Patent Application No. 58-19.
This is almost the same as the photostimulated excitation spectrum of the divalent europium-activated alkaline earth metal halide phosphor described in No. 3162. The wavelength range of the stimulated excitation spectrum is as wide as 450 to 11,000 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. It becomes possible to appropriately select a light source 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. Furthermore, from the viewpoint 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 preferably electromagnetic waves in the wavelength range of 500 to 850 nm.

The boron-coactivated divalent europium-activated alkaline earth metal halide phosphor represented by the above compositional formula (I) can be produced, for example, by the production method described below.

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

When producing a phosphor, first, using the above alkaline earth metal halide in 1), the boron compound in 2), and the europium compound in 3), the composition formula (■
): M"X2- aM"X'2: xEu, yB・
...(n) Cf:t:I,, M", X, X', 8,. and uyo
'The definition is the same as above).

The above mixture operation is carried out, for example, in the state of an aqueous solution. Then, by removing water from the aqueous solution of this phosphor raw material mixture, a solid dry mixture is obtained. This moisture 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 boron compound in 2) above may be added to this dry mixture without being added at the time of weighing and mixing the phosphor raw materials.

The resulting dry mixture is then finely ground.

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 suitably in the range of 500 to 1300°C, and the firing time varies depending on the filling amount of the phosphor raw material mixture and the firing temperature, but is generally suitable for 0.5 to 6 hours. As the firing atmosphere, a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen scum or a carbon dioxide atmosphere containing -carbon oxide is used. When the europium compound used contains trivalent europium, the weakly reducing atmosphere reduces the trivalent europium 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 at a firing temperature of 500 to 800° C. for 0.5 to 12 hours under the above-mentioned weak binary atmosphere or a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere.

- The phosphor used in the present invention is obtained by the above baking. The obtained phosphor may be subjected to various general operations in the production of phosphors, such as washing, drying, and sieving, if necessary.

By utilizing the manufacturing method described above, a boron-coactivated divalent europium-activated alkaline earth metal halide phosphor represented by the above-mentioned compositional formula (I) can be obtained.

In the radiation image conversion method of the present invention, the above composition formula (I)
The boron-coactivated divalent europium-activated alkaline earth metal halide phosphor represented by is preferably used in the form of a radiation image storage panel (also referred to as a stimulable phosphor sheet) containing it.

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 provides a radiation image conversion panel having a phosphor layer made of a divalent europium-activated alkaline earth metal halide phosphor co-activated with boron and represented by the above compositional formula (I). It is preferable to use

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 transmitted through the subject or emitted from the subject is The radiation is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the amount of radiation, and a radiation image of the subject or subject is formed on the radiation image conversion panel as an image of accumulated radiation energy. 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 create an image of 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 CI) is used in the form of a radiation image conversion panel. . 1 In Fig. 2, 11 is a radiation generating device such as an X-ray;
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 an excitation for emitting the accumulated radiation energy image on the radiation image conversion panel 13 as fluorescence. 15 is a photoelectric conversion device that detects fluorescence emitted from the radiation image conversion panel 13; 16 is a device that reproduces the photoelectric conversion signal detected by the photoelectric conversion device 15 as an image; 17 is a reproduced image and 18 is a filter that allows only the fluorescence emitted from the radiation image conversion panel 13 to pass through while not allowing the reflected light from the light source 14 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 in proportion to the intensity of the radiation. 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 11000 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.

For example, the radiation image accumulated on the radiation image conversion panel 13 is read by scanning the panel 13 with electromagnetic waves emitted from the light source 14, and detecting the fluorescence emitted from the panel 13 by this scanning using the photoelectric conversion device 15. , by obtaining time-series electrical signals.

In the radiation image conversion method of the present invention, the radiation used to obtain a radiation transmission image of the subject can exhibit stimulated luminescence when the phosphor is further excited by the electromagnetic waves after being irradiated with the radiation. Any type of radiation may be used, and for example, commonly known radiation such as X-rays, electron beams, and ultraviolet rays can be used.

Furthermore, the radiation directly emitted from the subject when obtaining a radiation image of 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, and beta rays.

As a light source of electromagnetic waves that excites the phosphor that has absorbed radiation from the subject or subject as described above, 45
In addition to the light source that emits light with a hentos vector distribution in the wavelength range of 0 to lo00 nm, there is also an Ar ion laser-1K.
Lasers such as r-ion lasers, He-Ne lasers, ruby lasers, semiconductor lasers, glass fist lasers, YAG lasers, dye lasers, and light sources such as light emitting diodes can be used. Among these, laser light is preferred as the excitation light source used in the present invention because it can irradiate the radiation image conversion panel with a laser beam with high energy source per unit area.
Yes. Among them, from the viewpoint of stability and output, the preferred laser beams are He-Ne laser and Ar ion laser-8! UKr4- to 7v-E1A6・Samurai・
Single semiconductor lasers are preferred as excitation light sources because they are compact, require low driving power, and can be directly modulated, making it easy to stabilize the laser output.

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 consists essentially of a support and an alkaline earth metal activated with divalent europium co-activated with boron represented by the compositional formula (I) provided on the support. and a stimulable phosphor layer comprising a binder containing and supporting a halide phosphor in a dispersed state. 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 seratin,
Polysancharides such as dextran, or natural polymeric substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride @ vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride/acetic acid Examples of binders include synthetic polymeric substances such as vinyl copolybutylene, polyurethane, cellulose acetate butylene, polyvinyl alcohol, and linear polyester. 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 transparent solvent and mixed thoroughly to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution. .

Examples of solvents for producing 1 h liquid temperature include lower alcohols such as methanol, ethanol, n-propanol, and n-butasol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, and methyl isobutyl. Ketones such as 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 methyl ether; and mixtures thereof. can.

The mixing ratio of the binder and the stimulable phosphor in the coating solution is
The mixing ratio of the binder and the phosphor is generally selected from the range of 1:1 to 1:1OO (weight ratio), although it varies depending on the characteristics of the radiation image conversion panel to be used and the type of phosphor. In particular, it is preferable to select from the range of 1:8 to 1:40 (weight ratio).

The coating liquid also contains a dispersant to improve the dispersibility of the phosphor in the coating liquid, 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. Examples of dispersants used for such purposes 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, and diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; and ethyl phthalyl ethyl glycolate and butyl phthalyl glycolate. Glycolic acid esters of triethylene glycol and adipine, and polyesters of polyethylene glycol and aliphatic dibasic acids, such as polyesters of diethylene glycol and amber.

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 a 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 materials known as supports for radiation image storage panels. 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, aluminum alloy foil, regular paper, baryta paper, resin. Examples include 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. A light-absorbing substance such as carbon blank may be kneaded into this plastic film, or a light-reflecting substance such as titanium dioxide may be kneaded into the plastic film. 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 (sharpness, granularity) of the radiation image conversion panel. A polymeric substance such as gelatin is coated on the surface of the side support to form an adhesion imparting layer, or a light reflective layer made of a light reflective material such as titanium dioxide or a light absorbing material such as carbon blank is used. It is known to provide an absorbent 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 and use 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 on the surface of the adhesive layer (meaning the surface thereof), minute irregularities may be formed thereon.

After forming the coating film on the support as described above, the coating film 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 pm to 1 mm.

However, the thickness of this layer is preferably 50 to 500 μm.

In addition, the stimulable phosphor layer does not necessarily need to be formed by directly applying a coating solution onto the support as described above, but can be formed by separately applying it onto a sheet such as a glass plate, metal plate, or plastic sheet. After forming a phosphor layer by applying a liquid and drying it.

The support and the phosphor layer may be bonded together by pressing this onto the support or using an adhesive.

The stimulable phosphor layer may be only one layer, but it may be two or more layers. In the case of six layers, at least one layer is a divalent europium-activated alkali co-activated with boron of composition formula (I). Any layer may be used as long as it contains an earth metal halide phosphor, and a plurality of phosphor layers may be stacked so that the luminous efficiency with respect to radiation increases sequentially toward the surface of the panel. Furthermore, in both the single-layer and multilayer cases, a known stimulable phosphor can be used in combination with the above-mentioned phosphor.

Examples of such known stimulable phosphors include, in addition to the above-mentioned phosphors, ZnS:Cu,Pb,BaO*xAl2O3, which is described in JP-A-55-12142:
Eu (however, 0.8≦x≦10), J:'bi,
M”O・xSi02:A (However, MI! is Mg, Ca
, Sr, Zn, Cd, or Ba, and A is Ce, T
b, Eu, Tm, Pb, T1. Bi or Mn, and X is 0.5≦X≦2.5), as described in JP-A-55-12143 (S)
a1-z-y, MgX, Cay)
F X :aEu2+ (X is C1 and Br
at least one of the following, and X and y are O<x
+7≦0°6・f's Q X y”r-with OT・
0 is 10-1≦a≦5×10-”),
and LnOX:xA described in JP-A-55-12144 (where Ln is at least one of La, Y, Gd, and Lu, and X is C1 and Br).
A is at least one 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 is, for example, a cellulose such as cellulose acetate or nitrocellulose + iA conductor;) +6 or a synthetic polymer material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copolymer. The phosphor layer can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a transparent polymeric substance such as 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 thus formed is preferably about 0.1 to 20 gm.

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

[Example 1 Co-culture barium (B a B r 2 ” 2 H20)
3332g, barium chloride (BaC Bun 2/2H20
) 244.3g, boron oxide (B203)O', 069
6g, and culture europium (EuBr3) 0.78
3 g of the sardine was added to 800 mM of distilled water (B20) and mixed to form an aqueous solution. This aqueous solution was dried under reduced pressure at 60°C for 3 hours, and then further vacuum dried at 150°C for 3 hours.

Next, the obtained phosphor raw material mixture was filled into an alumina crucible, which was then placed in a high-temperature electric furnace and fired. Firing is carried out at 900°C in a carbon dioxide atmosphere containing carbon oxide.
The test was carried out at a temperature of 1.5 hours. After the firing was completed, the fired product was taken out of the furnace and cooled. In this way, a divalent europium-activated barium chloride bromide phosphor co-activated with boron (BaC!;L2"BaBr2:0.
001Eu2+, 0.002B) was obtained.

Furthermore, by changing the amount of boron oxide in the range of 0 to 2.0 mol per mol of BaCu2/BaBr2, various types of divalent europium-activated barium chloride bromide co-activated with boron with different amounts of boron were prepared. Phosphor (BaC
Jlz・BaBr2: 0.001E u 2+, V
B) was obtained. Next, each phosphor obtained in Example 1 was irradiated with X-rays at a tube voltage of 80 KV p, and the brightness of stimulated luminescence when excited with semiconductor laser light (780 nm) was measured. did. The results are shown in FIG.

Figure 1 shows B a Cl 2 order B a B r 2
: 0.001E u2+ , yB is a graph showing the relationship between the amount of boron (y value) in the phosphor and the stimulated luminance.

As is clear from FIG. 1, the BaC statement 2*B of the present invention
aBr2: 0.001E u2+,yB The luminance of stimulated luminescence of the yB phosphor is improved when the y value is in the range of 2X10-'≦y≦2XIO-'. In particular, y
A phosphor having a value in the range of 4X10-'≦y≦10-1 exhibits high-intensity stimulated luminescence.

[Example 2] Divalent europium-activated barium chloride bromide phosphor co-activated with boron obtained in Example 1 (BaC12*BaB
rz + 0.001Eu-, 0,002B) were thoroughly loosened, methyl ethyl ketone was added to a mixture of the particles and linear polyester resin, and nitrocellulose with a degree of nitrification of 11.5% was added to disperse the phosphor. A dispersion containing the following was prepared. Next, tricresyl phosphate, n-butanol, and methyl ethyl ketone were added to this dispersion, and the mixture was sufficiently 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. is 1 = 10, viscosity is 25-35PS (25℃)
A coating solution was prepared.

Next, a titanium dioxide kneaded polyethylene tere-2-talate sheet (support, thickness: 2
The coating solution was applied uniformly onto the film (50 pm) using a doctor blade. After coating, the support on which the coating film has been formed is placed in a dryer, and the temperature inside the dryer is adjusted to 25°C.
The temperature was gradually increased from 100°C to 100°C to dry the coating film. In this way, a phosphor layer with a layer thickness of 250 gm was formed on the support.

Then, by placing and bonding a transparent film of polyethylene terephthalate (thickness: 12 pm, coated with a polyester adhesive) on top of this phosphor layer with the adhesive layer side facing down, a transparent protective film is formed. A radiation image storage panel consisting of a support, a phosphor layer and a transparent protective film was manufactured.

[Example 3] Boron was produced by performing the same operation as in Example 1, except that 210 g of ammonium borofluoride (N H4B Fa ) 0 was used instead of boron oxide. divalent europium-activated barium chloride bromide phosphor (Ba0 sentence 2 *BaBr
2:0.001Eu2+, 0.002B) was obtained.

Next, a radiation image conversion panel consisting of a support, a phosphor layer and a transparent protective film was manufactured by carrying out the same treatment as in Example 2 except for using this stimulable phosphor.

[Comparative Example 1] Divalent europium-activated barium chloride bromide phosphor (BaCl
2*BaBr2:0.001Eu24) was obtained.

Next, a radiation image conversion panel consisting of a support, a phosphor layer and a transparent protective film was manufactured by carrying out the same treatment as in Example 2 except for using this stimulable phosphor.

Each radiation image conversion panel obtained in Examples 2 and 3 and Comparative Example 1 was irradiated with X-rays with a tube voltage of 80 KVp and then excited with semiconductor laser light (780 nm). ) was measured. The result is the first
Shown in the table.

Table 1 Boron compounds Relative sensitivity Example 2 B2O3115 Example 3 N Ha B F 4 140 Comparative example 1 1
00

[Brief explanation of drawings]

FIG. 1 shows B, which is a specific example of the phosphor used in the present invention.
a(:J12 *BaBr2:0.001Eu2+,y
It is a graph which shows the relationship between the y value and the stimulated luminance luminance in B phosphor. FIG. 2 is a schematic diagram illustrating the radiation image conversion method of the present invention. 11: Radiation generator 12: Subject 13, Radiation image conversion panel 14: Light source 15: Photoelectric conversion device 16: Image reproduction device 17: Image display device 18: Filter Patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Yasuo Yanagawa No. Figure 1 y Direction Figure 2

Claims (1)

[Claims] 1. Radiation transmitted through the object or emitted from the object is transferred to a divalent europium-activated alkaline earth metal halide phosphor co-activated with boron expressed by the following compositional formula CI). After absorption, this phosphor has 450 to 1
By irradiating electromagnetic waves in the wavelength range of 1000n,
A radiation image conversion method characterized by emitting radiation energy accumulated in the phosphor as fluorescence and detecting this fluorescence. Composition formula (1): % formula % () (where M'' is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca;
and Xo are at least one kind of halogen selected from the group consisting of C1, Br and I, and
sX'; and a is a numerical value in the range of 0.1≦a≦10.0, X is a numerical value in the range of 0 < x≦0.2, and y is 2 X I O-'≦y ≦2 X I O−
2° in the compositional formula (I) is a numerical value in the range of 0.3≦a≦3.3. Method. 3゜y in compositional formula (I) or 4 X 10-'≦y≦
Feature 1.1 characterized by a numerical value in the range of 10-1
A radiation image conversion method according to claim 1. 2. The radiation image conversion method according to claim 1, wherein M or Ba is present in the 4° compositional formula (I). 5゜X and Xo in compositional formula (I) each represent C
The radiation image conversion method according to claim 1, characterized in that the material is either M or Br. 6゜X in compositional formula (I) is 10-'≦X≦10-1
The radiation image conversion method according to claim 1, characterized in that the value is in the range of . 7. 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. 8. The radiation image conversion method according to claim 1, wherein the radiation image conversion method is a bipedal electromagnetic wave or a laser beam. In a radiation image conversion panel substantially composed of a 9° support and a stimulable phosphor layer provided on the support, the stimulable phosphor layer is represented by the following compositional formula (I). A radiation image storage panel comprising a divalent europium-activated alkaline earth metal halide phosphor co-activated with boron. Composition formula (I): M"X2 m aM"X' 2 : xEu", yB・
...(I) (However, M" is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca:
and
~X′: and a is a numerical value in the range of 0.1≦a≦io, o, X is a numerical value in the range of O<x≦02,
y is a numerical value in the range of 2 X 10-'≦y≦2X10-') 10° A in the compositional formula (I) is a numerical value in the range of 0.3≦a≦3.3. Claim No. 9
The radiation image conversion panel described in Section 1. 11゜y in compositional formula (I) is 4X10''≦y≦1
10. The radiation image conversion panel according to claim 9, wherein the numerical value is in the range of 0-1. 12. The radiation image conversion panel according to claim 9, characterized in that MI [ or Ba in the 12° compositional formula (I) is selected from the group consisting of: 13° X and X'' in compositional formula (I) are each
The radiation image conversion panel according to claim 9, characterized in that it is either Cfl or Br. 14゜X in Ml formula (I) is l O-'≦X≦1
10. The radiation image conversion panel according to claim 9, wherein the numerical value is in the range of 0-1.