JP3538781B2 - Alkali halide phosphor, radiation image conversion panel using the phosphor, and radiation image conversion method using the radiation image conversion panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkali halide phosphor activated with thallium and lead, a radiation image conversion panel using the phosphor, and a radiation image reading method using the radiation image conversion panel.

[0002]

2. Description of the Related Art Conventionally, a so-called radiographic method using a silver salt has been used to obtain a radiographic image. However, a method of imaging a radiographic image without using a silver salt has been developed. That is, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited with a certain energy to emit the radiation energy stored in the phosphor as fluorescence, and the fluorescence is detected. A method for imaging is disclosed. As a specific method, a radiation image conversion method using a panel having a stimulable phosphor layer formed on a support and using one or both of visible light and infrared light as excitation energy is known (US Pat. No. 3,859, 52
No. 7).

As a radiation image conversion method using a stimulable phosphor, for example, a method described in Japanese Patent Application Laid-Open No.
A radiation image conversion method using an FX: Eu ²⁺ (X: Cl, Br, I) phosphor, a radiation image conversion method using an alkali halide phosphor described in JP-A-61-72087, etc. It has been known. In JP-A-61-73786 and 61-73787, Tl ⁺ and Ce ³⁺ , Sm ³⁺ , Eu ³⁺ ,
Alkali halide phosphors containing Y ³⁺ , Ag ⁺ , Mg ²⁺ , Pb ²⁺ , and In ³⁺ metals are known.

[0004]

When a radiation image conversion panel made of a stimulable phosphor is used for radiography such as X-ray photography for medical diagnosis, the radiation dose to the human body is reduced. Therefore, it is desired that the sensitivity of the radiation image conversion panel, that is, the stimulable light emission luminance of the stimulable phosphor is high. In addition, this accumulated image is usually accumulated by using laser light as excitation light and scanning the radiation image conversion panel with this laser light to excite the stimulable phosphor in the radiation image conversion panel in time series. The emitted radiation energy is emitted as fluorescence, and the fluorescence is detected by a photodetector. Therefore, the fluorescence that is still continuously emitted after the stimulable phosphor used in the radiation image conversion panel stops excitation by the excitation light, that is, afterglow (stimulation afterglow) is the S / N ratio of the obtained image. This may cause a decrease in the image quality, thereby deteriorating the image quality. Therefore, it is desirable that the stimulable phosphor used in the radiation image conversion panel has less stimulus afterglow, that is, does not emit light in a shorter time after the excitation by the excitation light is stopped.

However, the above-mentioned stimulable phosphors are not sufficiently satisfactory in terms of stimulable light emission luminance and stimulable afterglow, and improvement thereof is desired. Also, JP-A-61-737
In the alkali halide phosphors described in Nos. 86 and 61-73787, the content of the coactivator has a wide range of 0 to less than 0.2, and the coactivator need not be contained.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide an alkali halide phosphor having a higher stimulable emission luminance and less stimulus afterglow. It is another object of the present invention to provide a radiation image conversion panel that provides a radiation image having a higher luminous emission luminance and less luminous afterglow. It is another object of the present invention to provide a radiation image conversion method that provides a radiation image having a higher stimulus emission luminance and a lower stimulus afterglow.

[0007]

In accordance with the object of the present invention, as a result of various studies on a phosphor exhibiting high luminance stimulating light emission and having a small amount of stimulating afterglow, it is represented by the following general formula (1). The object of the present invention can be achieved by an alkali halide phosphor, a radiation image conversion panel using the phosphor, and a radiation image conversion method using the radiation image conversion panel.

General formula (1) M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : cTl ⁺ , dPb ²⁺ (where M ¹ is at least one selected from Li, Na, K, Rb and Cs) M ² is Be, M
g, at least one divalent metal selected from Ca, Sr, Ba, Zn, Cd, Cu and Ni, and M ³ is Sc, Y, L
a, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga and In are at least one trivalent metal, and X, X 'and X "are at least one halogen selected from F, Cl, Br and I. Also, a, b, c and d are respectively 0 ≦ a ≦ 0.3, 0 ≦ b ≦ 0.3, 10 ⁻⁶ ≦ c ≦ 10 ⁻² , 10 ⁻⁵
≦ d ≦ 10 ⁻³ . That is, when the alkali halide phosphor of the present invention is irradiated with radiation such as X-rays, ultraviolet rays, and electron beams, and then the phosphor is irradiated with one or both of visible light and infrared light to stimulate and stimulate the phosphor, it has been conventionally known. Compared to the case where the same operation is performed using the alkali halide phosphor, the photoluminescence exhibits a clearly stronger photostimulated luminescence, and the photostimulated afterglow is reduced.

Further, the alkali halide phosphor of the present invention can be used as a sensitizer, a phosphor for an X-ray image intensifier, and the like in addition to the radiation image conversion panel.

In the radiation image conversion panel of the present invention, basically, at least one of the support and at least one of the phosphors provided on one or both sides thereof is an alkali halide phosphor of the general formula (1). It consists of layers.

Further, the radiation image conversion method of the present invention is carried out in a mode using a radiation image conversion panel containing the alkali halide phosphor of the general formula (1).

Hereinafter, the structure of the present invention will be specifically described together with its operation.

FIG. 1 shows one of the phosphors according to the present invention.
RbI: 10 ^-4 Tl ^+, the DPB ²⁺ phosphor, tube voltage 80 KV _P, tube current 10mA
After irradiating with X-rays for 0.1 second, this is irradiated with a semiconductor laser beam (780
FIG. 3 is a diagram showing the relationship between the emission intensity due to the stimulus emitted from the phosphor layer and the Pb ²⁺ content when excited at 10 nm (nm, 10 mW). In FIG. 1, the ordinate represents d = 0, that is, RbI containing no Pb ²⁺ , and represents the relative intensity with the luminescence intensity due to the photostimulation of 10 ⁻⁴ Tl ⁺ phosphor set to 1. As is clear from FIG.
The emission intensity due to photostimulation is significantly enhanced by the inclusion of Pb ²⁺ , and a sufficient effect is obtained when the content d is in the range of 10 ⁻⁶ ≦ d ≦ 10 ⁻² , and particularly, 10 ⁻⁵ ≦ d ≦ 10 ^−. The effect is remarkable in the range of ³ .

The alkali halide phosphor of the present invention represented by the general formula (1) is produced, for example, by the following production method.

First, in the case of the firing method, 1) LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, K
F, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl,
One or more of CsBr and CsI, 2) BeF ₂ , BeCl ₂ , BeBr ₂ , BeI ₂ , MgF ₂ , MgCl ₂ , MgBr ₂ ,
_{MgI 2, CaF 2, CaCl 2} , CaBr 2, CaI 2, SrF 2, SrCl 2, SrB
r ₂ , SrI ₂ , BaF ₂ , BaCl ₂ , BaBr ₂ , BI ₂ , ZnF ₂ , ZnCl ₂ , Zn
Br ₂ , ZnI ₂ , CdF ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ , CuCl ₂ ,
_{CuBr 2, CuI 2, NiF 2} , NiCl 2, NiBr 2, NiI 2 2 divalent metal one or two or more of _{such, 3) ScF 3, ScCl 3} , ScBr 3, ScI 3, YF 3, YCl 3 , YBr ₃ , Y
I ₃ , LaF ₃ , LaCl ₃ , LaBr ₃ , LaI ₃ , CeF ₃ , CeCl ₃ , CeBr ₃ ,
CeI ₃ , PrF ₃ , PrCl ₃ , PrBr ₃ , PrI ₃ , NdF ₃ , NdCl ₃ , NdB
_{r 3, NdI 3, PmF 3} , PmCl 3, PmBr 3, PmI 3, SmF 3, SmCl 3, S
_{mBr 3, SmI 3, EuF 3} , EuCl 3, EuBr 3, EuI 3, GdF 3, GdC
_{l 3, GdBr 3, GdI 3} , TbF 3, TbCl 3, TbBr 3, TbI 3, DyF 3, D
_{yCl 3, DyBr 3, DyI 3} , HoF 3, HoCl 3, HoBr 3, HoI 3, Er
F ₃ , ErCl ₃ , ErBr ₃ , ErI ₃ , TmF ₃ , TmCl ₃ , TmBr ₃ , TmI ₃ ,
_{YbF 3, YbCl 3, YbBr 3} , YbI 3, LuF 3, LuCl 3, LuBr 3, Lu
I ₃ , AlF ₃ , AlCl ₃ , AlBr ₃ , AlI ₃ , GaF ₃ , GaCl ₃ , GaBr ₃ ,
One of trivalent metals such as GaI ₃ , InF ₃ , InCl ₃ , InBr ₃ , and InI ₃
Species or two or more, 4) TlF, TlCl, TlBr , TlI, Tl 2 O, Tl 2 O 3, TlOH, Tl 2 CO
₃ , one or more of thallium compounds such as TlNO ₃ , 5) PbF ₂ , PbCl ₂ , PbBr ₂ , PbI ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb
₃ O ₄ , PbSO ₄ , Pb (NO ₃ ) ₂ , PbCO ₃ , Pb (C ₁₇ H ₃₃ COO) ₂ , (CH ₃ C
One or more of lead compounds such as OO) ₂ Pb and (CH ₃ COO) ₂ Pb.3H ₂ O are used.

The raw materials are weighed so as to have a mixed composition represented by the general formula (1), and are sufficiently mixed using a ball mill, a mixer mill, a mortar or the like.

In the phosphor of the present invention, M ¹ in the general formula (1) is considered from the viewpoints of stimulating luminescence luminance and stimulating afterimage.
Is preferably at least one alkali metal selected from K, Rb and Cs. X is preferably at least one halogen selected from Br and I. M ²
Is preferably at least one divalent metal selected from Be, Mg, Ca, Sr and Ba. The M ³ Y,
At least one trivalent metal selected from Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In is preferred. M ³
B value representing the content of X ″ ₃ and d representing the content of Pb ²⁺
The values are preferably selected from the ranges of 0 ≦ b ≦ 10 ⁻² and 10 ⁻⁵ ≦ d ≦ 10 ⁻³ , respectively. Pb compounds having low melting points such as PbF ₂ , PbCl ₂ , PbBr ₂ , PbI ₂ , Pb (NO ₃ ) ₂ , and Pb (C ₁₇
H ₃₃ COO) ₂ , (CH ₃ COO) ₂ Pb, and (CH ₃ COO) ₂ Pb · 3H ₂ O are preferable, and Pb (NO ₃ ) ₂ is particularly preferable.

Next, the obtained phosphor raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace. The firing temperature is suitably from 400 to 1000 ° C, preferably from 500 to 700 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature, and the like.
2 to 10 hours are appropriate, preferably 1 to 4 hours.
As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere or an oxidizing atmosphere containing an oxygen gas is preferable. After firing once under the above firing conditions,
The fired product is taken out of the electric furnace and pulverized, and then the fired material powder is again filled in a heat-resistant container, placed in an electric furnace, and re-fired under the same firing conditions as described above, resulting in phosphor emission resulting in photostimulation. Brightness can be further increased. Also, when the fired material is cooled from the firing temperature to room temperature, the phosphor is moved from the heating unit to the cooling unit in the electric furnace, and rapidly cooled in a neutral atmosphere or an oxidizing atmosphere using a fan or the like. The stimulated emission luminance can be further increased.

By utilizing the property that the alkali halide constituting the base of the phosphor has a high solubility in water, the phosphor of the present invention can be prepared without a firing step as described in JP-A-63-179992. Can be obtained. That is,
The phosphor raw material is weighed so as to have a mixed composition represented by the general formula, dissolved or suspended in water, mixed well, and then water is evaporated by heating, drying under reduced pressure, vacuum drying, spray drying, or the like. By doing so, the phosphor of the present invention can be obtained.

Further, a stimulable phosphor or the like is previously added to a binder liquid by a vapor deposition method such as an evaporation method, a sputtering method, a CVD method, or an ion plating method as described in JP-A-61-73100. The phosphor of the present invention can be obtained by a coating method in which a phosphor coating prepared by dissolving and suspending in a single layer or a plurality of layers is divided according to performance and applied without performing the firing step.

When the phosphor layer is formed by the vapor deposition method, after the support is placed in the vapor deposition apparatus, the inside of the vapor deposition apparatus is evacuated to a degree of vacuum of about 10 ^{-6 to} 10 ^-2 Torr. Then
The phosphor raw material mixture similar to that shown in the firing method is heated and evaporated by a method such as a resistance heating method or an electron beam method to deposit the phosphor to a predetermined thickness on the surface of the support. Also,
The phosphor material may be co-evaporated using a plurality of resistance heaters or electron beams to synthesize a desired phosphor on the surface of the support and simultaneously form a phosphor layer. After forming the phosphor base layer containing no activator on the support, the activator may be doped into the phosphor base layer by a method such as a thermal diffusion method to form the phosphor layer. Further, at the time of vapor deposition, reactive vapor deposition may be performed by introducing a gas such as O ₂ or H _{2 as} necessary. After the deposition, the phosphor layer may be subjected to a heat treatment (annealing).

When the phosphor of the present invention is used as a radiation image conversion panel, it is preferable to prepare it by a vapor deposition method or a coating method. It is desirable to use the vapor deposition method because the light emitting luminance can be improved without causing a decrease in sharpness due to a high filling rate of. In the case of evaporation method,
The deposition rate of the phosphor layer is preferably 0.1 to 50 μm / min. If the deposition rate is too low, the productivity will be low, and if the deposition rate is too high, it will be difficult to control the deposition rate. The temperature of the support during the vapor deposition step is suitably 500 ° C. or less, and 300 ° C. to 40 ° C.
0 ° C. is preferred. If this temperature is too high, the sharpness of the image tends to decrease due to the progress of crystallization.

Next, a radiation image conversion panel using the alkali halide phosphor of the present invention will be described.

FIG. 2 is a cross-sectional view showing an example of the radiation image conversion panel, wherein 1 is a support, 2 is a phosphor layer, 3 is a low refractive index layer, 4 is a protective layer, and 5 is a spacer.

The material of the support 1 is preferably a material having sufficient heat resistance during vapor deposition and subsequent heat treatment, and examples thereof include glass ceramics, alumina, quartz glass, soda glass, and aluminum.
The thickness of the support 1 depends on its material and the like, but is generally preferably 0.1 to 5 mm.
In particular, 0.2 to 2 mm is preferable.

The surface of the support 1 may be smooth, or may be rough for the purpose of improving the adhesion to the phosphor layer 2. However, scattering of the excitation light on the substrate surface is suppressed as much as possible. In order to enhance the sharpness of the obtained image, the surface roughness is preferably 0.1 μm or less, more preferably 0.01 μm or less in terms of center line average roughness Ra (JIS B-0601). In addition, since the phosphor layer 2 is more likely to be peeled off as the surface of the support 1 is smoother, the phosphor layer 2 should be provided wider than the actual radiation image reading area, and the surface roughness of a portion other than the reading area should be increased. Is desirable. This makes it difficult to peel off. Methods for adjusting the surface roughness of the support 1 include sandblasting, powder spraying, lapping, etching with hydrofluoric acid and the like. The surface roughness Ra of the support 1 other than the reading area is preferably 0.1 μm or more in Ra, more preferably 0.5 μm or more.

Further, an undercoating layer may be provided on the surface of the support 1 on which the phosphor layer 2 is provided for the purpose of improving the adhesion to the phosphor layer 2, and it is necessary to adjust the light reflectance. Accordingly, a metal such as Al and an oxide layer such as SiO ₂ and Al ₂ O ₃ may be provided by a vacuum evaporation method, a sputtering method, a thermal spraying method, or the like. Further, a subbing layer may be provided on the surface of the support 1 on which the phosphor layer 2 is provided for the purpose of improving the adhesiveness to the phosphor layer 2, and if necessary, a light reflecting layer, a light absorbing layer, or the like. A layer or the like may be provided.

The thickness of the phosphor layer 2 is preferably 30 to 1000 μm, and more preferably 100 to 500 μm. When heat treatment is performed on the phosphor layer 2 formed by the vapor deposition method, sensitivity to X-rays is improved. Further, after a phosphor base layer containing no activator is formed on the support 1 or the protective layer 4, the activator is doped into the phosphor base layer by a method such as a thermal diffusion method to obtain a predetermined phosphor. It can also be a layer.

The protective layer 4 is provided to protect the phosphor layer 2 physically or chemically, and has high transparency and can be formed on a sheet. The protective layer 4 preferably has a high transmittance in a wide wavelength range in order to efficiently transmit stimulated excitation light and stimulated emission light. That is, the light transmittance is 70% in the wavelength range of 300 to 900 nm.
The above is preferable, and 90% or more is particularly preferable for the stimulating light having a wavelength of 350 to 500 nm and the stimulating light having a wavelength of 600 to 900 nm. Examples of such a material include plate glass such as quartz, borosilicate glass, and chemically strengthened glass, and organic polymer compounds such as polyethylene terephthalate (PET), drawn polypropylene, polyvinyl chloride, and acrylic resin. Borosilicate glass shows a light transmittance of 80% or more in the wavelength range of 330 to 2600 nm, and quartz glass shows a high light transmittance even at a shorter wavelength, and is particularly preferable. Further, it is preferable to provide an anti-reflection layer such as MgF _{2 on} the surface of the protective layer 4 because it has the effect of efficiently transmitting stimulated excitation light and stimulated emission light and increasing sharpness. The layer thickness of the protective layer 4 is, for example, 25 μm to 5 mm, and is 0.2 μm in order to obtain good moisture resistance and impact resistance and to secure a sufficient light transmittance.
1-3 mm is preferred.

The phosphor layer 2 may be in contact with both the support 1 and the protective layer 4, but it is necessary to provide a low refractive index layer 3 between the phosphor layer 2 and the protective layer 4 as shown in FIG. Is preferred. The low-refractive-index layer 3 exists in a state where it is shielded from the external atmosphere, and the presence of the low-refractive-index layer 3 substantially reduces the thickness of the protective layer 4 without lowering sharpness. And the moisture resistance and durability can be further improved. Examples of such a low refractive index layer 3 include a layer made of an inert gas such as air, nitrogen, and argon, and a layer having a refractive index of substantially 1, such as a vacuum layer;
Layer composed of liquid such as methyl alcohol (refractive index 1.33), ethyl alcohol (refractive index 1.36), CaF ₂ (refractive index 1.23)
~ 1.26), Na ₃ AlF ₆ (refractive index 1.35), MgF ₂ (refractive index 1.3
8) and a substance such as SiO ₂ (refractive index 1.46). Among these, the low refractive index layer 3 composed of a gas layer or a vacuum layer is particularly preferred because it has a high effect of preventing the sharpness of an image from lowering. The thickness of the low refractive index layer 3 is usually 0.05 μm
~ 3 mm is practical.

The spacer 5 is not particularly limited as long as it can hold the phosphor layer 2 in a state of being shielded from the external atmosphere, and examples thereof include glass, ceramics, metal, and plastic.

FIG. 3 schematically shows an embodiment in which the alkali halide phosphor represented by the general formula (1) is used in the form of a radiation image conversion panel (hereinafter, conversion panel) in the radiation image conversion method of the present invention. .

An object 102 is composed of a conversion panel 103 and a radiation source 101.
Then, when the radiation source 101 is turned on, a transmitted radiation image of the subject 102 is recorded and accumulated in the stimulable phosphor 104 of the conversion panel 103. Thereafter, the conversion panel 103 is scanned by a stimulating light source 105 such as a laser through a mirror 106, and the stimulating light emitted from the stimulable phosphor 104 is transmitted to a light transmitting means 108.
Is detected by the photodetector 107 via the. At this time, the transport stage 109 performs, for example,
The entire photostimulated luminescence is detected. The time-sequential photostimulated light emission signal is amplified by an amplifier 111 and then converted to an A / D converter.
It is sent to the storage means 113 through 112. Also, conversion panel 10
An erasing light source 110 is provided at a position facing the phosphor-side surface of No. 3, and after detecting stimulated emission, erases the latent image accumulated in the phosphor.

[0034] As the stimulating light source 105, the He-Ne laser, the He-Cd laser, Ar ion laser, Kr ion laser, N ₂ laser, YAG laser and its second harmonic, Bireza, semiconductor lasers, various Lasers such as a dye vapor laser and a metal vapor laser such as a copper vapor laser are exemplified. It is preferable that the light source for stimulating excitation light be small, have high output, and have good matching with the stimulating excitation spectrum. When the light source light includes a portion overlapping the photostimulated emission spectrum, it is preferable to use a filter that cuts off the spectrum portion. Further, it is preferable to use a filter for passing the stimulated emission and cutting off the stimulated excitation light in the photoelectric converter, and it is preferable that the photoelectric converter and the filter have good photoelectric conversion system sensitivity and good matching with the stimulated emission light.

The erasing light source 110 is a stimulable phosphor 1
Reference numeral 04 denotes a light source that emits light including the excitation wavelength region of the phosphor, such as a halogen lamp, a tungsten lamp, an infrared lamp, and an LED as disclosed in JP-A-56-11392.
Alternatively, a laser light source or the like can be arbitrarily selected and used.

[0036]

EXAMPLES Examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these embodiments.

Example 1 Each of the phosphor raw materials was weighed into the combinations shown in the following (1) to (17), and then thoroughly mixed using a ball mill to prepare the following phosphor raw material mixtures.

(1a) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 33.123 g (10 ^-1 mol) (1b) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^{− 4} mol) Pb (NO ₃ ) ₂ 3.3123 g (10 ^-2 mol) (1c) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.3312 g (10 ^-3 mol) ( 1d) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.0331 g (10 ^-4 mol) (1e) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.0033 g (10 ^-5 mol) (1f) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.0003 g (10 ^-6 mol) (1 g) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.00003 g (10 ^-7 mol) (2) KBr 119.01 g (1 mol) BaBr ₂ 29.716 g (10 ^-1 mol) TlBr 0.0284 g ( ^10-4 mol) PbBr ₂ 0.0367 g (10 ^-4 mol) (3) CsI 259.81 g (1 mol) SmCl ₃ 0.2567 g (10 ^-3 mol) TlCl 0.0240 g (10 ^-4 mol) (CH ₃ COO) ₂ Pb 0.0325 g (10 ^-4 mol) (4) RbBr 165.38 g (1 mol) SrBr ₂ 2.4744 g (10 ^-2 mol) TlNO ₃ 0.0266 g (10 ^-4 mol) PbI ₂ 0.0461 g (10 ^-4 mol) (5) KI 83.003 g (0.5 mol) CsCl 84.179 g (0.5 mol) Tl ₂ O 0.0425 g (10 ^-4 mol) Pb Cl ₂ 0.0243 g (10 ^-4 mol) (6) RbI 212.37 g (1 mol) CeI ₃ 5.2083 g (10 ^-2 mol) TlI 0.0331 g (10 ^-4 mol) PbI ₂ 0.0461 g (10 ^-4 mol) (7 ) KI 166.01 g (1 mol) MgI ₂ 27.812 g (10 ^-1 mol) TlI 0.0331 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.0331 g (10 ^-4 mol) (8) KCl 74.555 g (1 mol) CaCl ₂ 11.099 g (10 ^-1 mol) TlCl 0.0240 g (10 ^-4 mol) PbSO ₄ 0.0303 g (10 ^-4 mol) (9) NaI 149.89 g (1 mol) EuBr ₃ 0.3917 g (10 ^-3 mol) Tl 0.0331 g ^{(10 -4 mol) PbO 0.0223g (} 10 -4 mol) (10) RbBr 165.38g (1mol) YF 3 14.590g (10 -1 mol) TlBr 0.0284g (10 -4 mol) PbBr 2 0.0367g (10 - ( ⁴ mol) (11) RbCl 12092 g (1 mol) BeI ₂ 0.2628 g (10 ^-3 mol) TlCl 0.0240 g (10 ^-4 mol) PbCl 0.0243 g (10 ^-4 mol) (12) NaBr 102.90 g (1 mol) AlBr ₃ ^{0.0267g (10 -4 mol) TlBr 0.0284g} (10 -4 mol) PbCO 3 0.0267g (10 -4 mol) (13) PbI 212.37g (1mol) InF 3 1.7182g (10 -2 mol) TlI 0.0331g ( (10 ^-4 mol) PbF ₂ 0.0245 g (10 ^-4 mol) (14) CsBr 212.84 g (1 mol) LaI ₃ 5.1962 g (10 ^-2 mol) TlBr 0.0284 g (10 ^-4 mol) Pb (NO ₃ ) ₂ 0.0331 g (10 ^-4 mol) (15) LiI 133.84 g (1 mol) GdBr ₃ ^{0.0397g (10 -4 mol) TlI 0.0331g} (10 -4 mol) PbI 2 0.0461g (10 -4 mol) (16) RbF 104.47g (1mol) LuF 3 0.2320g (10 -3 mol) TlF 0.0223g ( ^10-4 mol) PbO ₂ 0.0239 g (10 ^-4 mol) (17) KF 58.100 g (1 mol) GaCl ₃ 0.0018 g (10 ^-5 mol) TlF 0.0223 g (10 ^-4 mol) Pb ₂ O ₃ 0.0462 g ( 10 ^-4 mol) Ra: A support provided with a light reflection layer composed of an Al / SiO ₂ sputtered film on the surface of a crystallized glass plate of 0.001 μm was placed in an electron beam evaporator, and then the phosphor thus prepared was mixed. The raw material mixtures (1) to (17) were put into a crucible which was press-formed and water-cooled as an evaporation source. After that, the inside of the evaporator was once evacuated, and then N ₂ gas was introduced to adjust the degree of vacuum to 1 × 10 ⁻³ Torr. Then, while maintaining the temperature of the support at about 350 ° C., the inside of the crucible was irradiated with an electron beam gun. The surface of the deposition source was scanned in a raster shape and evaporated to deposit. When the thickness of the phosphor layer became 300 μm, the deposition was terminated, and then
This phosphor layer was heated at a temperature of 400 ° C. In a dry air atmosphere, the periphery of the support and the protective layer made of borosilicate glass were sealed with an adhesive to obtain radiation image conversion panels (1) to (17) having a structure in which the phosphor layer was sealed. .

The tube voltage at a distance of 100cm the radiation image conversion panel from the X-ray tube focal point, respectively 80 KV _P, tube current
After irradiating with a 10 mA X-ray for 0.1 second, it was excited with a semiconductor laser beam (780 nm, 10 mW), and the fluorescence due to stimulus emitted from the phosphor layer was measured with a photodetector. Table 1 shows the results.
It is shown in Table 17.

Comparative Example 1 The following phosphors (1) to (17) were prepared in the same manner as in Example 1 except that the raw materials of the respective phosphors were weighed into the combinations shown in the following (1) to (17). Obtained.

(1) RbI 212.37 g (1 mol) TlI 0.0331 g (10 ^-4 mol) (2) KBr 119.01 g (1 mol) BaI ₂ 39.115 g (10 ^-1 mol) TlBr 0.0284 g (10 ^-4 mol) ( 3) CsI 259.81 g (1 mol) SmCl ₃ 0.2567 g (10 ^-3 mol) TlCl 0.0240 g (10 ^-4 mol) (4) RbBr 165.38 g (1 mol) SrI ₂ 3.4143 g (10 ^-2 mol) TlNO ₃ 0.0266 g (10 ^-4 mol) (5) KI 83.003 g (0.5 mol) CsCl 84.179 g (0.5 mol) TlI 0.0331 g (10 ^-4 mol) (6) RbI 212.37 g (1 mol) CeBr ₃ 3.7985 g (10 ^-2 mol ) TlI 0.0331 g (10 ^-4 mol) (7) KI 166.01 g (1 mol) MgI ₂ 27.812 g (10 ^-1 mol) TlI 0.0331 g (10 ^-4 mol) (8) KCl 74.555 g (1 mol) CaCl ₂ 11.099 g (10 ^-1 mol) TlCl 0.0240 g (10 ^-4 mol) (9) NaI 149.89 g ( ¹ mol) EuBr ₃ 0.3917 g (10 ^-3 mol) TlI 0.0331 g (10 ^-4 mol) (10) RbBr 165.38 g (1 mol) YF ₃ 14.590 g (10 ^-1 mol) TlBr 0.0284 g (10 ^-4 mol) (11) RbCl 12092 g (1 mol) BeI ₂ 0.2628 g (10 ^-3 mol) TlCl 0.0240 g (10 ^-4 mol) ( 12) NaBr 102.90 g (1 mol) AlBr ₃ 0.0267 g (10 ^-4 mol) TlBr 0.0284 g (10 ^-4 mol) (13) PbI 212.37 g (1 mol) InF ₃ 1.7182 g (10 ^-2 mol) Tl 0.0331 g ( 10 ^-4 mol) (14) CsBr 212.84 g (1 mol) LaI ₃ 5.1962 g (10 ^-2 mol) TlBr 0.0284 g (10 ^-4 mol) (15) LiI 133.84 g (1 mol) GdBr ₃ 0.0397 g (10 ^-4 mol) TlI 0.0331 g ^{(10 -4 mol) (16)} RbF 104.47g (1mol) LuF 3 0.2320g (10 -3 mol) TlF 0.0223g (10 -4 mol) (17) KF 58.100g (1mol) GaCl 3 0.0018g (10 - ⁵ mol) TlF 0.0223 g (10 ^-4 mol) Using these phosphors (1) to (17), a radiation image conversion panel was obtained in the same manner as in Example 1, and a semiconductor laser was further formed in the same manner as in Example 1. The stimulable light emission luminance was measured using this method. The results are also shown in Tables 1 to 17.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

[0047]

[Table 6]

[0048]

[Table 7]

[0049]

[Table 8]

[0050]

[Table 9]

[0051]

[Table 10]

[0052]

[Table 11]

[0053]

[Table 12]

[0054]

[Table 13]

[0055]

[Table 14]

[0056]

[Table 15]

[0057]

[Table 16]

[0058]

[Table 17]

Tables 1 to 17 show that the samples (1) to (1) of the present invention were prepared.
The emission luminance of the phosphor of (17) due to photostimulation was determined by the comparative samples (1) to (17) made of the conventionally known phosphor shown in Comparative Example 1.
Is extremely higher than the emission luminance due to the measured stimulus.

Table 1 and FIG. 1 show the stimulable luminescence intensity with respect to the Pb ²⁺ content when RbI: Tl ⁺ contains Pb ²⁺ . The content of Pb ²⁺ is
In 10 ^{-6 to} 10 ^-2 , the stimulated emission intensity increases, and further,
It can be seen that it is extremely high in 10 ^{-5 to} 10 ^-3 . So
Table 1 also shows the state of photostimulated afterglow.
You. That is, the content of Pb ²⁺ is 10 ^{−6 with respect} to the base material 1 of the phosphor.
To the ^10-2 becomes less bright尽残light rate, further, ^10-5 乃
It can be seen that very low in optimum 10 ^-3.

Example 2 The radiation image conversion panels (1) to (1) used in Example 1 were used.
Tube voltage at 100cm distance 7) from the X-ray tube focal point, respectively 80 KV _P, after irradiation 0.1 sec X-ray tube current 10 mA, using a function generator emitting diode (680 nm)
For 5 ms, and the time change (decay) of the stimulated emission intensity emitted from the phosphor after the excitation was stopped was measured. 5 after stopping the excitation light for the intensity immediately before stopping the excitation light
The intensity after milliseconds was defined as the afterglow intensity, and the results are shown in Tables 1 to 17.

Comparative Example 2 The stimulus afterglow was determined in the same manner as in Example 2 except that the radiation image conversion panel used in Comparative Example 1 was used. Table 1 shows the results
To Table 17 together.

As shown in Tables 1 to 17, the samples (1) to
The stimulus afterglow of the phosphor of (17) is extremely smaller than the stimulus of afterglow measured in Comparative Samples (1) to (17), which are composed of the conventionally known phosphors shown in Comparative Example 1.

[0064]

As described above, the phosphor of the present invention has a significantly increased photostimulated luminous intensity as compared with the conventional alkali halide phosphor, and the photostimulated afterglow is greatly reduced. Therefore, when the radiation image conversion method using the radiation image conversion panel of the present invention is used for X-ray diagnosis or the like, the amount of X-ray exposure of the subject can be reduced due to high sensitivity, and the afterglow is reduced. Since the number is small, the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the Pb ²⁺ content of the phosphor of the present invention and the emission intensity due to its stimulus.

FIG. 2 is a sectional view of a radiation image conversion panel according to one embodiment of the present invention.

FIG. 3 is a schematic view of an embodiment of the method of the present invention for performing image conversion using the phosphor of the present invention for the radiation image conversion panel of the present invention.

[Explanation of symbols]

1 Support 2 Phosphor layer 3 Low refractive index layer 4 Protective layer 5 Spacer 101 radiation source 103 Conversion Panel 104 Stimulable phosphor 105 Stimulated excitation light source 106 mirror 107 Photodetector 108 Light transmission means 109 Transfer stage 110 Light source for erasure 111 amplifier 112 A / D converter 113 Memory

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09K 11/61 G03C 5/17 G21K 4/00

Claims (3)

(57) [Claims] 1. An alkali halide phosphor characterized in that the composition formula is represented by the general formula (1). General formula (1) M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : cTl ⁺ , dPb ²⁺ (where M ¹ is at least one kind of alkali metal selected from Li, Na, K, Rb and Cs) And M ² is Be, M
g, at least one divalent metal selected from Ca, Sr, Ba, Zn, Cd, Cu and Ni, and M ³ is Sc, Y, L
a, Ce, Pr, Nd, Pm, Sm, Eu , Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga and In are at least one trivalent metal, and X, X 'and X "are at least one halogen selected from F, Cl, Br and I. Also, a, b, c and d are respectively 0 ≦ a ≦ 0.3, 0 ≦ b ≦ 0.3 , 10 ⁻⁶ ≦ c ≦ 10 ⁻² , 10 ⁻⁵
≦ d ≦ 10 ⁻³ . ) 2. In a radiation image conversion panel having a support and at least one phosphor layer provided on the support, at least one of the phosphor layers is represented by the following general formula (1). A radiation image conversion panel comprising an alkali halide phosphor. General formula (1) M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : cTl ⁺ , dPb ²⁺ (where M ¹ is at least one kind of alkali metal selected from Li, Na, K, Rb and Cs) And M ² is Be, M
g, at least one divalent metal selected from Ca, Sr, Ba, Zn, Cd, Cu and Ni, and M ³ is Sc, Y, L
a, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga and In are at least one trivalent metal, and X, X 'and X "are at least one halogen selected from F, Cl, Br and I. Also, a, b, c and d are respectively 0 ≦ a ≦ 0.3, 0 ≦ b ≦ 0.3, 10 ⁻⁶ ≦ c ≦ 10 ⁻² , 10 ⁻⁵
≦ d ≦ 10 ⁻³ . ) 3. A radiation image is radiated on the radiation image conversion panel by irradiating a radiation image on the radiation image conversion panel having a phosphor layer by irradiating the radiation with the radiation to the radiation object. In a radiation image conversion method of storing and recording, converting the stored and recorded radiation energy into stimulating light by stimulating excitation with excitation light, and reproducing a radiation image, at least one of the phosphor layers has the following general formula: A radiation image conversion method comprising an alkali halide phosphor represented by the formula (1). General formula (1) M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : cTl ⁺ , dPb ²⁺ (where M ¹ is at least one kind of alkali metal selected from Li, Na, K, Rb and Cs) And M ² is Be, M
g, at least one divalent metal selected from Ca, Sr, Ba, Zn, Cd, Cu and Ni, and M ³ is Sc, Y, L
a, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga and In are at least one trivalent metal, and X, X 'and X "are at least one halogen selected from F, Cl, Br and I. Also, a, b, c and d are respectively 0 ≦ a ≦ 0.3, 0 ≦ b ≦ 0.3, 10 ⁻⁶ ≦ c ≦ 10 ⁻² , 10 ⁻⁵
≦ d ≦ 10 ⁻³ . )