JPH07287328A - Transformation of radiation image and phosphor - Google Patents

Abstract

PURPOSE:To provide a transforming method of a radiation image using a new stimulable phosphor. CONSTITUTION:In this transformation method of a radiation image, radiation transmitted through an objective body 12 or emitted from the objective body is absorbed and accumulated in a phosphor expressed by ZnO:nX (X is Zn, EuBr3, MgO or the like and (n) is 0.00001 to 0.1); BaO:nEuBr3 ((n) is 0.00001 to 0.1); and MgO:nEuBr3 ((n) is 0.00001 to 0.1). Then the phosphor is irradiated with electromagnetic waves in 450-800nm wavelength region to stimulate the radiation energy accumulated in the phosphor to emit as stimulated light. This stimulated light is detected. The stimulable phosphor used is expressed by ZnO:nX (X is EuBr3, MgO or the like, (n) is 0.00001 to 0.1); BaO:nEuBr3 ((n) is 0.00001 to 0.1); and MgO:nEuBr3 ((n) is 0.00001 to 0.1).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel photostimulable phosphor and a radiation image conversion method using the novel photostimulable phosphor.

[0002]

2. Description of the Related Art Conventionally, a so-called radiographic method has been used as a method for obtaining a radiographic image as an image by using a combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen (intensifying screen). Is used.

On the other hand, in recent years, as one of the methods to replace the above radiographic method, a radiation image conversion utilizing a stimulable phosphor as described in JP-A-55-12145. A method (radiation image recording / reproducing method) was developed,
Has received attention. This method involves absorbing and accumulating radiation transmitted through a subject or radiation emitted from a subject in a stimulable phosphor, and then exciting this phosphor with electromagnetic waves (excitation light) such as visible light and infrared light. By
Radiation energy accumulated in a phosphor is emitted as fluorescence (stimulated luminescence), the fluorescence is photoelectrically read to obtain an electric signal, and the electric signal is visualized.

According to the above radiation image recording / reproducing method,
Compared with the case of using the conventional radiography, there is an advantage that a radiographic image having a large amount of information can be obtained with a much smaller exposure dose. Therefore, this radiographic image recording / reproducing method is very useful particularly in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

In the above-mentioned radiation image conversion method, a stimulable phosphor that emits light (stimulated luminescence) by being irradiated with radiation such as X-ray and then excited by electromagnetic waves in the visible or infrared region is used. As such a stimulable phosphor, conventionally, a divalent europium-activated alkaline earth metal fluorohalide phosphor (M ^II FX: Eu ²⁺ ; where M ^II is a group consisting of Mg, Ca and Ba) Which is at least one alkaline earth metal selected from the group X is at least one halogen selected from the group consisting of Cl, Br and I); europium and samarium activated strontium sulfide phosphor (SrS: Eu, Sm) ); Europium and samarium activated lanthanum oxysulfide phosphor (La ₂ O ₂ S:
Eu, Sm); europium oxide aluminum barium phosphor _{(BaO · Al 2 O 3:} Eu); europium-activated alkaline earth metal silicate phosphor (M ²⁺ O · Si
O ₂ : Eu; provided that M ²⁺ is at least one alkaline earth metal selected from the group consisting of Mg, Ca and Ba); cerium-activated rare earth oxyhalide phosphor (LnOX: Ce; provided that Ln Is La, Y, Gd and L
is at least one rare earth element selected from the group consisting of u, and X is at least one halogen selected from the group consisting of Cl, Br, and I).

Of these, the divalent europium-activated alkaline earth metal fluorohalide phosphor has a high stimulated emission luminance (stimulated emission sensitivity) and is highly useful. However, since the above-mentioned phosphor is easily dissolved in water, it is inferior in moisture resistance, and is also insufficient in heat resistance, resulting in a problem that chemical stability is inferior. The density of the phosphor is about 5.2 g /
Since it is as small as cm ³ and the number of moles of the phosphor per unit volume is also low, it is disadvantageous in obtaining a high stimulated emission luminance per unit area of the sheet in an embodiment using this as a sheet-shaped radiation image conversion panel. is there.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radiation image conversion method using a novel photostimulable phosphor. Another object of the present invention is to provide a novel stimulable phosphor that can be advantageously used in a radiation image conversion method.

[0008]

Means for Solving the Problems The present inventors have searched for a stimulable phosphor, and as a result, a phosphor obtained by firing a composition having a specific metal oxide as a basic skeleton is found. The present invention has been newly found that it shows stimulated emission.

In the present invention, the radiation transmitted through the subject or emitted from the subject is detected as ZnO: nX (where X is
Is Zn, EuBr ₃ , ZnBr ₂ , CBr ₄ , Ba
O, CaO, MgO, NiO, VO, Al ₂ O ₃ , B ₂
At least one selected from the group consisting of O ₃ , Gd ₂ O ₃ and Sm ₂ O ₃ ; and n is 0.00001
In the range of ~0.1), BaO: nEuBr ₃ (where, n is in the range of 0.00001) and MgO:. NEuBr ₃ (where, n is 0.00001
It is in the range of 0.1. Radiation energy accumulated in the phosphor by irradiating the phosphor with electromagnetic waves in the wavelength region of 450 to 800 nm after being absorbed and accumulated in the metal oxide phosphor having a composition selected from the group consisting of Is emitted as photostimulable light, and the photostimulable light is detected.

The present invention also provides ZnO: nX (provided that
X is EuBr ₃ , ZnBr ₂ , CBr ₄ , BaO, C
aO, MgO, NiO, VO, Al ₂ O ₃ , B ₂ O ₃ ,
At least one selected from the group consisting of Gd ₂ O ₃ and Sm ₂ O ₃ ; and n is 0.00001 to 0.
1) in the photostimulable phosphor.

The preferred embodiments of the above stimulable phosphor are as follows. 1) The above X is EuBr ₂ , ZnBr ₃ and CBr ₄
It is at least one bromide selected from the group consisting of: 2) X is BaO, CaO, MgO, NiO, V
O, AL ₂ O ₃ , B ₂ O ₃ , Gd ₂ O ₃ and Sm ₂ O ₃
It is at least one oxide (preferably MgO) selected from the group consisting of 3) The above n is in the range of 0.0001 to 0.01.

The present invention also provides BaO: nEuBr ₃
(However, n is in the range of 0.00001 to 0.1 (preferably 0.0001 to 0.01).).

Further, the present invention provides MgO: nEuBr ₃
(However, n is in the range of 0.00001 to 0.1 (preferably 0.0001 to 0.01)). The above ZnO: nX, BaO: n
The formula represented by EuBr ₃ and MgO: nEuBr ₃ represents the raw material composition for obtaining the phosphor,
It does not represent the composition of the phosphor obtained by firing.

The photostimulable phosphor of the present invention absorbs or accumulates radiation transmitted through an object or emitted from an object, and then the phosphor absorbs and accumulates radiation in the range of 450 to 800.
Radiation energy accumulated in the phosphor is emitted as stimulated light by irradiating an electromagnetic wave in the wavelength region of nm, and is advantageously used in a radiation image conversion method comprising detecting this stimulated light. can do.

The photostimulable phosphor of the present invention is a photostimulable phosphor layer of a radiation image conversion panel comprising a support and a photostimulable phosphor layer provided on one surface of the support. It can be advantageously used as a stimulable phosphor.

ZnO: Zn obtained by firing ZnO
(That is, the phosphor represented by the above ZnO: nX (X = Zn)) is described in Phosphor Handbook, 28.
Page 0 (Ohm Co., Ltd., issued December 25, 1987)
However, in this document, it is described as an example of a phosphor for a cathode ray tube, and there is no suggestion that this phosphor exhibits photostimulability.

ZnO: nX (where X is Zn, E
uBr ₃ etc., a phosphor represented by BaO: nEuBr
Phosphor represented by _3, and MgO: phosphor represented by NEuBr ₃ is what to have a stimulable was newly found this time.

The phosphor represented by the above ZnO: nX (X = Zn) Zn is 0.00001 with respect to the raw material compounds ZnO or ZnO and ZnO, like the ordinary phosphors.
To 0.1 mol (preferably 0.0001 to 0.01 mol) of Zn at a temperature of about 700 to 1200 ° C. under an atmosphere of an inert gas such as nitrogen or a noble gas,
It can be manufactured by firing under reducing conditions or in a halogen gas atmosphere. Furthermore, it is preferable to perform firing at a temperature of 900 to 1100 ° C. in an atmosphere of an inert gas such as nitrogen or a noble gas. The phosphor can be subjected to known treatments such as crushing treatment, sieving treatment and washing treatment, if necessary.

ZnO: nX (when X is not Zn)
In represented by phosphor to ZnO as a raw material compound, further _{EuBr 3, ZnBr 3, CBr 4} , BaO, Ca
O, MgO, NiO, VO, AL ₂ O ₃ , B ₂ O ₃ , G
At least one kind (preferably MgO) selected from the group consisting of d ₂ O ₃ and Sm ₂ O ₃ is 0.00001 to 0.1 mol (preferably 0.0001) with respect to ZnO.
˜0.01 mol), and a raw material mixture obtained by adding and mixing can be produced by firing in the same manner as above. The phosphor can be subjected to known treatments such as crushing treatment, sieving treatment and washing treatment, if necessary. Examples of compounds added to ZnO include EuBr ₃ and
ZnBr ₃ , CBr ₄ and MgO are preferred, especially E
uBr ₃ is preferred.

The phosphor represented by the above BaO: nEuBr ₃ has a composition of Ba.O.
00001 to 0.1 mol (preferably 0.0001 to
0.01 mol) of EuBr ₃ are mixed and the mixture is mixed with 9
It can be manufactured by firing at a temperature of 00 to 1400 ° C. under an atmosphere of an inert gas such as nitrogen or a noble gas, under reducing conditions or under a halogen gas atmosphere. Furthermore, 110
It is preferable to perform firing at a temperature of 0 to 1300 ° C. in an atmosphere of an inert gas such as nitrogen or a noble gas. The phosphor can be subjected to known treatments such as crushing treatment, sieving treatment and washing treatment, if necessary.

The phosphor represented by the above MgO: nEuBr ₃ has Mg.
00001 to 0.1 mol (preferably 0.0001 to
0.01 mol) of EuBr ₃ are mixed and the mixture is mixed with 5
It can be produced by firing at a temperature of 00 to 1000 ° C. under an atmosphere of an inert gas such as nitrogen or a noble gas, under reducing conditions or under a halogen gas atmosphere. Furthermore, 600
It is preferable to perform firing at a temperature of up to 900 ° C. in an atmosphere of an inert gas such as nitrogen or a noble gas. The phosphor can be subjected to known treatments such as crushing treatment, sieving treatment and washing treatment, if necessary.

Since the above-mentioned phosphor is usually used in the radiation image conversion method in the form of a radiation image conversion panel, it is used in the stimulable phosphor layer of the radiation image conversion panel in that case. A radiation image conversion panel generally comprises a support and a stimulable phosphor layer made of a binder which is provided on the support and contains and supports the stimulable phosphor in a dispersed state. However,
The stimulable phosphor layer may be composed of only phosphor particles, or a sintered body of phosphor or a vapor-deposited layer, and the binder is not always necessary.

The most general radiation image conversion panel can be manufactured, for example, by the method described below. First, the stimulable phosphor particles and the binder are added to an appropriate solvent (for example, lower alcohol, chlorine atom-containing hydrocarbon, ketone, ester, ether), and they are thoroughly mixed to prepare a binder solution. A coating liquid in which the stimulable phosphor is uniformly dispersed is prepared. Examples of the binding agent include binding agents represented by proteins such as gelatin, polyvinyl acetate, nitrocellulose, polyurethane, polyvinyl alcohol, polyalkyl (meth) acrylate, and synthetic polymer substances such as linear polyester. be able to. The mixing ratio of the binder and the stimulable phosphor in the coating liquid is usually selected from the range of 1: 8 to 1:40 (weight ratio).

Next, the coating solution is uniformly applied to the surface of the support to form a coating film of the coating solution, and the coating film is dried to form a stimulable phosphor layer on the support. Complete the formation of. The layer thickness of the stimulable phosphor layer is generally 50 to 50.
It is 0 μm. The support can be appropriately selected from various materials used as a support for an intensifying screen (or intensifying screen) in a conventional radiographic method or a support for a known radiation image conversion panel. Examples of such materials include films of plastic substances such as cellulose acetate, polyethylene terephthalate,
Examples include metal sheets such as aluminum foil, ordinary paper, baryta paper, and resin-coated paper. In addition,
An adhesiveness-imparting layer, a light-reflecting layer, a light-absorbing layer or the like may be provided on the surface of the support on which the phosphor layer is provided, and the support is provided with fine irregularities uniformly. (If the adhesion-providing layer, the light-reflecting layer, the light-absorbing layer, etc. are provided on the surface of the support on the side of the phosphor layer, these irregularities are formed on the surface).

A transparent protective film for physically and chemically protecting the phosphor layer may be provided on the surface of the stimulable phosphor layer opposite to the side in contact with the support. Examples of materials used for the transparent protective film include cellulose acetate,
Examples thereof include polymethylmethacrylate, polyethylene terephthalate, and polyethylene. The thickness of the transparent protective film is usually about 0.1 to 20 μm.

A radiation image conversion panel using the phosphor of the present invention is disclosed in JP-A-55-163500 and JP-A-57-63500.
It may be colored with a colorant as described in JP-A-96300 and the like.
White powder may be dispersed in the stimulable phosphor layer as described in Japanese Patent No. 6447.

The radiation image conversion method of the present invention is applied to the above Zn
A case where a stimulable phosphor such as O: nZn is used in a form in which it is contained in a radiation image conversion panel will be specifically described with reference to the schematic diagram shown in FIG.

In FIG. 1, 11 is a generator for radiation such as X-rays, 12 is a subject, 13 is a radiation image conversion panel containing a phosphor, and 14 is an accumulated image of radiation energy on the radiation image conversion panel 13. An excitation source (light source) for emitting light as light, 15 is a photoelectric conversion device that detects photostimulated light emitted from the radiation image conversion panel 13, and 16 is an electric signal detected by the photoelectric conversion device 15 that is reproduced as an image. Device, 17 is a device for displaying the reproduced image, and 18
Is a filter for transmitting only the stimulated light emitted from the radiation image conversion panel 13 without transmitting the reflected light from the light source 14.

Although FIG. 1 shows an example in which a radiation transmission image of a subject is obtained, when the subject 12 itself emits radiation (this is referred to as a subject in the present specification), It is not necessary to specifically install the radiation generator 11 of. In addition, the photoelectric conversion device 15 and the image reproduction device 1
6 and the image display device 17 may be replaced with other suitable devices capable of visualizing and reproducing the image information emitted from the radiation image conversion panel 13 as stimulating light in some way.

As shown in FIG. 1, when the subject 12 is irradiated with radiation such as X-rays from the radiation generator 11, the radiation passes through the subject 12 in proportion to the radiation transmittance of each part thereof. The radiation transmitted through the subject 12 is
The light enters the radiation image conversion panel 13 and is absorbed by the stimulable phosphor layer of the radiation image conversion panel 13 in proportion to the intensity of the radiation. That is, an accumulated image of radiation energy (a kind of latent image) corresponding to a radiation transmission image is formed on the radiation image conversion panel 13.

Next, the light source 1 is attached to the radiation image conversion panel 13.
When the electromagnetic wave in the wavelength region of 450 to 800 nm is irradiated using the No. 4, the accumulated image of the radiation energy formed on the radiation image conversion panel 13 is emitted as stimulating light. The emitted photostimulable light is proportional to the intensity of the radiation energy absorbed in the photostimulable phosphor layer of the radiation image conversion panel 13. Image information consisting of the intensity of this bright stimulus,
For example, it is converted into an electric signal by the photoelectric conversion device 15 such as a photomultiplier tube, reproduced as an image by the image reproduction device 16, and displayed by the image display device 17.

The operation of reading out the image information accumulated in the radiation image conversion panel as photostimulable light is generally performed by scanning the panel in a time series with a laser beam, and the photostimulable light emitted from the panel by this scanning is appropriately collected. It is carried out by detecting with a photodetector such as a photomultiplier tube through the optical body to obtain a time-series electric signal. This read-out may be composed of a pre-reading operation by irradiating low-energy excitation light and a main reading operation by irradiating high-energy excitation light in order to obtain an image having a better observation / interpretation performance (JP-A-58). -67
No. 240). By performing this pre-read operation, there is an advantage that the read condition in the main read operation can be set appropriately.

A solid-state photoelectric conversion element such as a photoconductor and a photodiode may be used as the photoelectric conversion device (see Japanese Patent Laid-Open No. 58-121874). In this case, a large number of solid-state photoelectric conversion elements are configured so as to cover the entire surface of the panel and may be integrated with the panel, or may be arranged in the state of being close to the panel. Further, the photoelectric conversion device may be a line sensor in which a plurality of photoelectric conversion elements are linearly connected, or may be composed of one solid-state photoelectric conversion element corresponding to one pixel.

The light source in the above case may be a point light source such as a laser, or a line light source such as an array in which light emitting diodes (LEDs) and semiconductor lasers are connected in a row. By performing reading using such a device, it is possible to prevent the loss of photostimulated light emitted from the panel, and at the same time increase the light receiving solid angle to increase the S / N ratio. Further, the obtained electric signal is not time-sequentially irradiated with the excitation light but is time-sequentially processed by the electric processing of the photodetector, so that the reading speed can be increased.

The radiation image conversion panel from which the image information has been read is irradiated with light in the wavelength region of the excitation light of the photostimulant or is heated.
The remaining radiation energy may be erased, which is preferable (see JP-A-56-11392 and JP-A-56-12599). By performing this erasing operation, it is possible to prevent generation of noise due to an afterimage when the panel is used next time. Furthermore, by performing the erasing operation twice after the reading and immediately before the next use, it is possible to prevent the generation of noise due to natural radioactivity and to perform the erasing more efficiently (see Japanese Patent Laid-Open No. 57-116300). ).

In the radiation image conversion method of the present invention, the radiation used when obtaining a radiation transmission image of a subject is as follows: when the stimulable phosphor is irradiated with this radiation and is excited by the electromagnetic wave. Any radiation may be used as long as it can exhibit stimulated emission, such as X
Commonly known radiation such as rays, electron rays, and ultraviolet rays can be used. Further, the radiation emitted directly from the subject in the case of obtaining a radiation image of the subject may be any radiation as long as it is absorbed by the stimulable phosphor and becomes an energy source of stimulated luminescence. As an example thereof, radiation such as γ-ray, α-ray, β-ray and the like can be mentioned.

As a light source of excitation light for exciting the stimulable phosphor that has absorbed the radiation from the subject or the subject, in addition to a light source that emits light having a band spectrum distribution in the wavelength region of 450 to 800 nm, For example, a laser such as an Ar ion laser, a Kr ion laser, a He-Ne laser, a ruby laser, a semiconductor laser, a glass laser and a dye laser, and a light source such as a light emitting diode can also be used. Among them, the laser can irradiate the radiation image conversion panel with a laser beam having a high energy density per unit area,
Various lasers are preferable as the excitation light source used in the present invention. Among them, the He—Ne laser is particularly preferable in terms of matching with the stimulable excitation spectrum of the stimulable phosphor of the present invention. In addition, the semiconductor laser has a small size and a small driving power,
It is preferable as a light source for excitation because it can be directly modulated and the laser output can be easily stabilized.

The light source used for erasing may be one that emits light in the excitation wavelength region of the stimulable phosphor, and examples thereof include a tungsten lamp, a stimulant lamp,
Mention may be made of halogen lamps.

The radiation image conversion method of the present invention comprises a storage part for absorbing and accumulating radiation energy in the stimulable phosphor, and irradiating the stimulable phosphor with excitation light to release the energy of the radiation as stimulable light. It can also be applied to a built-in type radiation image conversion device in which a photodetection (readout) unit for causing the emission and an erasing unit for releasing the energy remaining in the stimulable phosphor are built in one device.

[0040]

【Example】

[Example 1] Production of ZnO: Zn 81.37 g (1 mol) of zinc oxide (ZnO) was charged into an alumina crucible, which was placed in a high-temperature electric furnace for firing. Firing is performed at a temperature of 1000 ° C. in a nitrogen atmosphere for 2 hours.
It took time. After firing was completed, the fired product was taken out of the furnace, cooled, loosened, and washed with methanol. Thus, a powdery phosphor (ZnO: Zn) was obtained.

[Examples 2 to 15] Examples 2 to 15 except that the following compounds were added to 81.37 g (1 mol) of zinc oxide (ZnO) and fired in the same manner as in Example 1 A phosphor in powder form was obtained in the same manner as in 1. Barium oxide (BaO) 0.15 g (0.001 mol) ... [Example 2] Calcium oxide (CaO) 0.006 g (0.0001 mol) ... [Example 3] Magnesium oxide (MgO) 0.004 g (0.0001 mol) ... [Example 4] vanadium oxide (VO) 0.007 g (0.0001 mol) ... [Example 5] aluminum oxide (Al ₂ O ₃ ) 0.10 g (0.001) mol) example 6 boron oxide _{(B 2 O 3) 0.007g (} 0.0001 moles) .... [example 7] oxidation Gadomiumu _{(Gd 2 O 3) 0.37 g} (0.001 mol) - example 8 samarium oxide _{(Sm 2 O 3) 0.035 g} (0.0001 mol) example 9 europium bromide (EuBr ₃₎ 0.39 g (0.001 mol) example 10 four carbon bromide (CBr ₄₎ 0.033 g (0.0001 mol) ... Example 11 carbon tetrabromide (CBr ₄₎ 0.33 g (0.01 mol) ...... [Example 12] zinc bromide (ZnBr ₂₎ 0.23 g (0.001 mol) [Example 13] Zinc (Zn) 0.007 g (0.0001 mol) ... [Example 14] Zinc (Zn) 0.65 g (0.01 mol) ... ........... [Example 15]

Among the phosphors produced as described above, the stimulated excitation spectrum of the phosphor obtained in Example 1 is shown in FIG. 2, and the stimulated emission spectrum (radiation) thereof is shown in FIG. The stimulated excitation spectrum of the phosphor obtained in Example 10 is shown in FIG. 4, and the stimulated emission spectrum (UV
And radiation) are shown in FIGS.

Next, the relative stimulated emission luminance (relative PSL) of the phosphors (Examples 1 to 15) produced as described above.
Was measured. The value is tube voltage 40KV-3 for each phosphor powder.
After irradiation with X-ray under the condition of 0 mA-120 seconds, He-N
The stimulated emission intensity generated when excited by e laser light (633 nm) is a relative value obtained by converting the luminance of ZnO: Zn obtained in Example 1 into 1. Table 1 shows the obtained relative stimulated emission intensity.

[0044]

[Table 1] Table 1 ───────────────────────── Additive stimulated emission intensity (mol) (relative value) ────── ─────────────────── Example 1-1.00 Example 2 BaO (1 × 10 ⁻³ ) 1.57 Example 3 CaO (1 × 10 ⁻⁴⁾ ) 1.80 Example 4 MgO (1 × 10 ^-4 ) 3.57 Example 5 VO (1 × 10 ^-4 ) 1.53 Example 6 Al ₂ O ₃ (1 × 10 ^-3 ) 1.80 Implementation Example 7 B ₂ O ₃ (1 × 10 ^-4 ) 1.96 Example 8 Gd ₂ O ₃ (1 × 10 ^-3 ) 2.02 Example 9 Sm ₂ O ₃ (1 × 10 ^-4 ) 2.60 Example 10 EuBr ₃ (1 × 10 ⁻³ ) 6.00 Example 11 CBr ₄ (1 × 10 ⁻⁴ ) 1.85 Example 12 CBr ₄ (1 × 10 ⁻² ) 2.96 Example 13 ZnBr ₂ (1 × 10 ⁻³ ) 3.52 Example 14 Zn (1 × 10 ⁻⁴ ) 1.70 Example 15 Zn (1 × 10 ⁻² ) 2.28 ───────────── ─────────────

[Example 16] Barium oxide (BaO) 1
53.34 g (1 mol) and europium bromide (Eu
Br ₃₎ 0.039 g of (0.0001 mol) was charged into an alumina crucible and subjected to firing take this into high-temperature electric furnace. Firing is performed at a temperature of 1250 ° C. in a nitrogen atmosphere for 2 hours.
It took time. After firing was completed, the fired product was taken out of the furnace, cooled, loosened, and washed with methanol. In this way, the powdered phosphor (BaO: 0.0
001.EuBr ₃ phosphor) was obtained.

Next, FIG. 7 shows the phosphor stimulated emission spectrum (radiation) produced as described above.

[Example 17] Magnesium oxide (Mg)
O) 40.31 g (1 mol) and EuBr ₃ 0.039
An alumina crucible was charged with g (0.0001 mol), and the alumina crucible was placed in a high-temperature electric furnace for firing. The firing was performed in a nitrogen atmosphere at a temperature of 750 ° C. for 2 hours.
After firing is completed, the fired product is taken out of the furnace and cooled,
After loosening, it was washed with methanol. In this way, the powdered phosphor (MgO: 0.0001.EuBr)
₃ phosphor) was obtained.

Next, FIG. 8 shows the stimulated excitation spectrum of the phosphor produced as described above. The stimulated emission light of this phosphor was detected near 400 nm.

Example 18 Production of Radiation Image Conversion Panel 600 g of the powdered phosphor obtained in Example 10 and polyurethane resin (manufactured by Sumitomo Bayer Urethane Co., desmolak 4)
215) 15.8 g and bisphenol A type epoxy resin 2.0 g were added to methyl ethyl ketone-toluene (1:
It was added to the mixed solvent of 1) and dispersed by a propeller mixer to prepare a coating liquid having a viscosity of 20 to 30 PS. This coating solution was applied onto a polyethylene terephthalate sheet support with an undercoat layer using a doctor blade and then 100
It was dried at 15 ° C. for 15 minutes to form a stimulable phosphor layer. Next, a transparent protective film is formed by adhering a polyethylene terephthalate film with an adhesive layer (thickness: 10 μm) on the photostimulable phosphor layer, and the support, the photostimulable phosphor layer and the transparent protective film are formed. A constructed radiation conversion panel was produced.

[0050]

The phosphor having a basic skeleton of the metal oxide of the present invention is already known as ZnO: Zn, but it is a novel photostimulable phosphor. , Can be advantageously used in a radiation image conversion method. That is, the phosphor of the present invention has the advantage that it has good chemical stability such as humidity resistance and heat resistance, and has a high density (eg, ZnO: Zn: about 5.8 g / cm ^3). , BaO: about 5.7 g / cm ³ ), so that the X-ray absorption amount is large and the density is high, so the number of moles of the phosphor per unit volume is also low. In the embodiment utilized as, since a high packing degree per unit area of the sheet is obtained, it can be said that the phosphor is advantageous in obtaining a high stimulated emission luminous intensity.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a radiation image conversion method of the present invention.

FIG. 2 is a photostimulated excitation spectrum of a phosphor represented by ZnO: Zn.

FIG. 3 is a stimulated emission spectrum of a phosphor represented by ZnO: Zn.

FIG. 4 is a photostimulated excitation spectrum of a phosphor represented by ZnO: 0.001.EuBr ₃ .

FIG. 5 is a UV stimulated emission spectrum of a phosphor represented by ZnO: 0.001.EuBr ₃ .

FIG. 6 is a photostimulated emission spectrum by radiation of a phosphor represented by ZnO: 0.001.EuBr ₃ .

FIG. 7: Radiation-stimulated emission spectrum of a phosphor represented by BaO: 0.0001.EuBr ₃ .

FIG. 8 is a photostimulated excitation spectrum of a phosphor represented by MgO: 0.0001.EuBr ₃ .

[Explanation of symbols]

 11 Radiation Generation Device 12 Subject 13 Radiation Image Conversion Panel 14 Light Source 15 Photoelectric Conversion Device 16 Image Reproduction Device 17 Image Display Device 18 Filter

Claims (4)

[Claims] 1. Radiation transmitted through a subject or emitted from a subject is ZnO: nX (where X is Z
n, EuBr ₃ , ZnBr ₂ , CBr ₄ , BaO, Ca
O, MgO, NiO, VO, Al ₂ O ₃ , B ₂ O ₃ , G
at least one selected from the group consisting of d ₂ O ₃ and Sm ₂ O ₃ ; and n is 0.00001 to 0.
It is in the range of 1. ), BaO: nEuBr ₃ (however, n
Is in the range of 0.00001 to 0.1. ) And Mg
O: nEuBr ₃ (where n is 0.00001 to 0.1
Is the range. After being absorbed and accumulated in a metal oxide phosphor having a composition selected from the group consisting of
A radiation image conversion method comprising irradiating an electromagnetic wave in the wavelength region of up to 800 nm to release the radiation energy accumulated in the phosphor as stimulating light, and detecting the stimulating light. 2. ZnO: nX (where X is EuBr)
₃ , ZnBr ₂ , CBr ₄ , BaO, CaO, MgO,
At least one selected from the group consisting of NiO, VO, Al ₂ O ₃ , B ₂ O ₃ , Gd ₂ O ₃ and Sm ₂ O ₃ ; and n is in the range of 0.00001 to 0.1) A stimulable phosphor represented by. 3. BaO: nEuBr ₃ (where n is 0.
It is in the range of 00001 to 0.1. ) A stimulable phosphor represented by. 4. MgO: nEuBr ₃ (where n is 0.
It is in the range of 00001 to 0.1. ) A stimulable phosphor represented by.