JPS6121499B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a divalent metal fluorohalide phosphor and a radiation image storage panel having a phosphor layer comprising the phosphor. Traditionally, a so-called photographic method has been used to obtain radiation images as images, using a photographic film having an emulsion layer made of a silver salt photosensitive material, but in recent years silver salts have been used due to problems such as the depletion of silver resources. It has become desirable to develop a method of imaging radiographic images without By the way, some types of phosphors emit light when they are made to absorb radiation such as ionizing radiation, electron beams, vacuum ultraviolet rays, and ultraviolet rays, and then are excited by electromagnetic waves such as visible light or infrared rays. This phenomenon is called ``stimulable phosphor'', and a phosphor that exhibits ``stimulable phosphor'' is called a ``stimulable phosphor''. A radiation image conversion method using a light body is known (U.S. Patent No.
No. 3859527). This method uses a radiation image conversion panel (so-called storage type radiation image conversion panel) that has a phosphor layer made of a photostimulable phosphor, and the phosphor layer of the panel receives radiation that has passed through the subject. After absorbing the phosphor layer, the phosphor layer is excited with visible light or infrared rays to cause the stimulable phosphor to emit the accumulated radiation energy as fluorescence, and by detecting this, a radiation image of the subject is obtained. It is something. When this radiation image conversion method is put into practice, the radiation is often ionizing radiation such as X-rays and the subject is a person, and therefore it is necessary to reduce the exposure dose of the subject as much as possible. From this point of view, it is desired that the stimulable phosphor used in the radiation image conversion panel has higher stimulable luminance. The compositional formula is ( _{B a1- x} , _M〓 and a, x and y are numbers satisfying the following conditions, respectively: 0.5≦a≦1.25, 0≦x≦1 and 10 ^-6 ≦y≦2×10 ^-1 ) The europium-activated divalent metal fluorohalide phosphor is a practical photostimulable phosphor, and after irradiation and absorption, the
When excited with 800 nm light, it exhibits high-intensity stimulated luminescence. Some of these europium-activated divalent metal fluorohalide phosphors are known. For example, Japanese Patent Application Publication No. 55
-12143 and JP-A-55-12145, the composition formula is (B _a1-x , M〓x)FX:yEu (where M〓 is at least one of magnesium, calcium, strontium, zinc, and cadmium). species, X is at least one of chlorine, bromine, and iodine, and x and y are each 0
A divalent metal fluorohalide stimulable phosphor is described, which is a number satisfying the following conditions: ≦x≦0.6 and ≦y≦2×10 ^-1 . As mentioned above, when a photostimulable phosphor is used in a radiation image conversion panel, a photostimulable phosphor exhibiting higher luminance stimulated luminescence is desired, so the europium-activated divalent metal is used. A stimulable phosphor that exhibits higher luminance stimulated luminescence than a fluorohalide phosphor is desired. Accordingly, an object of the present invention is to provide a phosphor that exhibits stimulated luminescence with higher brightness than the conventional europium-activated divalent metal fluorohalide phosphor. Furthermore, the present invention also provides the above-mentioned conventional europium activated 2
It is an object of the present invention to provide a radiation image conversion panel having higher sensitivity than a radiation image conversion panel having a phosphor layer made of a valent metal fluorohalide phosphor. In order to achieve the above object, the present inventors have conducted various experiments on a europium co-activator, which is an activator for the phosphor. As a result, they discovered that if an appropriate amount of at least one of zirconium and scandium is contained in a phosphor as a coactivator for europium, the luminance of light emitted by exhaustion of the phosphor can be significantly improved. The present invention has now been completed. The divalent _metal fluorohalide phosphor of the present invention has a compositional formula of (B _{a1-x , M〓} At least one of cadmium, X is at least one of chlorine, bromine, and iodine, A is at least one of zirconium and scadinium, and a, x, y, and z are each 0.5≦a≦
1.25, 0≦x≦1, ^{10 -6} ≦y≦2×10 ^-1 and 0
It is a number that satisfies the condition <z≦10 ^-2 ). Further, the radiation image conversion panel of the present invention is a radiation image conversion panel having a phosphor layer made of a photostimulable phosphor, in which the above-mentioned photostimulable phosphor is
It is characterized by comprising a valent metal fluorohalide phosphor. The phosphor of the present invention can contain ionizing radiation such as X-rays and γ-rays,
After irradiating and absorbing radiation such as electron beams, vacuum ultraviolet rays, and ultraviolet rays, and then excitation with light with a wavelength of 450 to 800 nm, a phosphor with significantly higher volatility than conventional europium-activated divalent metal fluorohalide phosphors is produced. Shows stimulated luminescence. Therefore, the radiation image conversion panel of the present invention having a phosphor layer made of the phosphor of the present invention is different from the conventional radiation image conversion panel having a phosphor layer made of a europium-activated divalent metal fluorohalide phosphor. Significantly more sensitive than panels. From the viewpoint of stimulated luminescence volatility, the more preferable y and z value ranges of the compositional formula of the phosphor of the present invention are 10 ^-5 ≦y≦10 ^-2 , respectively.
and 5×10 ⁻⁶ ≦z≦5×10 ⁻³ . Further, the phosphor of the present invention can be used for ionizing radiation, electron beams, vacuum ultraviolet rays,
It also emits high-intensity near-ultraviolet to blue light (instantaneous light emission) when excited by radiation such as ultraviolet rays. Furthermore, the phosphor of the present invention can be applied to ionizing radiation, electron beams, vacuum ultraviolet rays,
When heated after being irradiated with radiation such as ultraviolet rays and absorbed, it exhibits high-intensity thermal fluorescence. The phosphor of the present invention is manufactured by the manufacturing method described above. First, the raw materials for the phosphor include barium fluoride (BeF ₂ ), beryllium fluoride (BeF ₂ ), magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), strontium fluoride (SrF ₂ ), and zinc fluoride ( One or more divalent metal fluorides consisting of ZnF ₂ ) and cadmium fluoride (CdF ₂ ), barium chloride (BaCl ₂ ), barium bromide (BaBr ₂ ), barium iodide (BaI ₂ ), chloride One or more halides consisting of ammonium (NH ₄ Cl), ammonium bromide (NH ₄ Br) and ammonium iodide (NH ₄ I) Europium chloride (EuCl ₃ ), europium oxide (Eu ₂ O ₃ ) , europium fluoride ( _EuF3 ),
selected from the group consisting of one or more europium compounds such as europium sulfate [Eu ₂ (SO ₄ ) ₃ ], and zirconium compounds and scandium compounds such as chlorides, fluorides, bromides, nitrates, oxides, etc. One or more compounds may be used. The above raw materials for _each phosphor are stoichiometrically expressed as ( _{B a1-x ,} M〓 at least one kind, X is at least one kind of chlorine, bromine and iodine, A is at least one kind of zirconium and scandium, a, x, y and z are each 0.5≦a≦
1.25, 0≦x≦1, ^{10 -6} ≦y≦2×10 ^-1 and 0
<z≦10 ^-2 ) The mixture composition is weighed and thoroughly mixed using a ball mill, mixer mill, etc. Note that when the x value of the above mixed composition formula is 0, the above phosphor raw material) is unnecessary, and when the x value is 1, the above phosphor raw material) is unnecessary, and the above phosphor raw material ) It is essential to use at least barium halide. In addition, one of the phosphor raw materials
When using ammonium halide (NH ₄ During the calcination process, it is dissipated out of the reaction system as NH ₄ X. Next, the raw material mixture is filled into a heat-resistant container such as an alumina crucible or a quartz crucible, and fired in an electric furnace. The firing temperature is suitably 600 to 1000°C, preferably 700 to 950°C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature employed, etc., but in general, 1 to 6 hours is appropriate.
Firing may be performed in air, but it is preferable to perform firing in a neutral atmosphere such as an argon gas atmosphere or a nitrogen gas atmosphere, or in a weakly reducing atmosphere such as a carbon atmosphere or a nitrogen gas atmosphere containing a small amount of hydrogen gas. . Incidentally, the luminance of the resulting phosphor can be further increased by firing once under the above firing conditions, taking the fired product out of the electric furnace, pulverizing it, and then firing it again under the same conditions. The phosphor of the present invention is obtained by pulverizing the fired material obtained after the calcination, and then performing various operations generally employed in the production of phosphors, such as washing, drying, and sieving. The divalent metal fluorohalide phosphor of the present invention produced as described above exhibits higher luminance stimulated luminescence than conventional europium-activated divalent metal fluorohalide phosphors, and Shows instantaneous luminescence and thermal fluorescence. Figure 1 illustrates the emission spectrum of photostimulation when the phosphor of the present invention is irradiated with 80 KVp X-rays and then excited with 630 nm light, and curves a and b represent BaF ₂ and BaBr ₂ , respectively. :0.0002Fu，0.0002Zr
Fluorescent material and ( _{Ba 0.95} , Mg _{0.05 )} F ₂・BaBr ₂ :
This is the emission spectrum of 0.0002Eu and 0.0002Zr phosphors. As is clear from FIG. 1, the divalent metal fluorohalide phosphor of the present invention has an emission spectrum of approximately 390 nm, similar to the conventional divalent metal fluorohalide phosphor using only europium as an activator. Shows near-ultraviolet to blue stimulated luminescence with a peak. The instantaneous emission spectrum of the phosphor of the present invention when excited with radiation such as X-rays, electron beams, and ultraviolet rays was also almost the same as the stimulated emission spectrum illustrated in FIG. Even if the composition of the phosphor of the present invention changes within the range of the above-mentioned compositional formula, the emission spectrum hardly changes. Shows exhaustive and instantaneous luminescence. Figure 2 shows _BaF2, one of the phosphors of the present invention.
BaBr ₂ :0.0002Eu, the amount of zirconium (z value) for the zZr phosphor and the 80KVp
It is a graph showing the relationship between luminescence brightness when photoexcitation is caused by excitation with 630 nm light after irradiation with a ray. In Figure 2, the vertical axis showing the photostimulated luminance is the conventional one in which zirconium is not co-activated.
BaF ₂・BaBr ₂ : Shown as a relative value with the stimulated luminance of the 0.0002Eu phosphor as 100. As is clear from Figure 2, when the amount of europium activation (y value) is constant, when the z value is in the range of 0<z≦10 ^-2 , BaF ₂ · BaBr ₂ : 0.0002Eu, zZr firefly The phosphor exhibits stimulated luminescence with higher brightness than the conventional BaF ₂ / BaBr ₂ :0.0002Eu phosphor, and even within this range, especially at 5×
When 10 ^-6 ≦z≦5×10 ^-3 , even higher luminance stimulated luminescence is exhibited. In addition, Figure 2 shows BaF ₂・
BaBr ₂ :0.0002Eu, This is a graph showing the relationship between the z value and the stimulated luminance for the zZr phosphor.
Even when the value changes, and when the coactivator (A) is scandium or consists of both zirconium and scandium, the relationship between the z value and the stimulable emission brightness tends to be almost the same as in Figure 2. It was confirmed that there is. It was also confirmed that even if the matrix composition was changed within the range of the above compositional formula, the relationship between the z value and the stimulable luminance was almost the same as that shown in FIG. 2. The range of europium activation amount (y value) in the divalent metal fluorohalide phosphor of the present invention is 10 ^-6 as in the case of the conventional divalent metal fluorohalide phosphor using only europium as an activator. ≦y≦
It is 2×10 ^-1 . A more preferable y value range from the viewpoint of stimulable luminance is 10 ^-5 _≦ y≦10 ^-5 . Furthermore, the M value (x value) range and the _Ba As in the case of fluorescent materials, the conditions are limited to 0≦x≦1 and 0.5≦a≦1.25, respectively. The excitation spectrum of the divalent metal fluorohalide phosphor of the present invention is almost the same as that of the conventional divalent metal fluorohalide phosphor using only europium as an activator. The body is
It exhibits stimulated luminescence when excited by light with a wavelength of 450 to 800 nm, and within this wavelength range, it exhibits stimulated luminescence.
It exhibits high-intensity stimulated luminescence when excited by light with a wavelength of 700 nm. Next, the radiation image conversion panel of the present invention will be explained. The radiation image conversion panel of the present invention is the above-mentioned radiation image conversion panel of the present invention.
It has a phosphor layer made of a valent metal fluorohalide phosphor. Generally, the phosphor layer is formed by dispersing the phosphor in a suitable binder. If the phosphor layer is self-supporting, the phosphor layer itself can serve as a radiation image conversion panel, but generally the phosphor layer is formed on one or both sides of a sheet-like support to absorb radiation. It is considered to be an image conversion panel. Furthermore, the surface of the phosphor layer (the surface of the phosphor layer opposite to the support) is usually provided with a protective film for physically or chemically protecting the phosphor layer. Further, an undercoat layer may be provided between the phosphor layer and the support for the purpose of increasing the degree of adhesion between the phosphor layer and the support. The radiation image storage panel of the present invention is generally manufactured as follows. First, a phosphor coating solution is prepared by mixing 0.01 to 1 part by weight of a binder with 1 part by weight of the divalent metal fluorohalide phosphor of the present invention, and this is horizontally coated using an appropriate coating method. A phosphor layer is formed by coating it on a support placed on a substrate and drying it to form a radiation image storage panel. In this case, the binder used is a binder commonly used for layer formation, such as nitrified cotton, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetate, or polyurethane. Various sheet-like materials such as plastic sheets, glass plates, paper, and metal plates can be used as the support, but materials that are flexible and easy to process are preferred for handling purposes. It is particularly preferable to use a plastic sheet or paper such as starate film or cellulose acetate film.
The thickness of the phosphor layer is appropriately set in the range of 10 to 1000 μm. Furthermore, when providing a protective film on the phosphor layer of the radiation image conversion panel, polyvinyl chloride, polyethylene teresterate, polymethacrylate,
Either a coating solution containing a resin such as cellulose acetate dissolved in an appropriate solvent is applied directly and dried, or a transparent thin film made of these resins is separately formed in advance and adhered to the surface of the phosphor layer. Forms a protective film. In addition, when providing a phosphor layer on a support, the phosphor layer is formed by directly applying a coating liquid containing a photostimulable phosphor dispersed in a binder onto the support as described above. Alternatively, a separately formed phosphor layer may be adhered onto the support. As explained above, when the phosphor of the present invention is irradiated with and absorbed radiation such as ionizing radiation, electron beam, vacuum ultraviolet ray, ultraviolet ray, etc., and then excited with light of 450 to 800 nm, the phosphor of the present invention can be produced using only europium as an activator. 2
It exhibits stimulated luminescence with higher brightness than valent metal fluorohalide phosphors. Therefore, the radiation image conversion panel of the present invention having a phosphor film made of the phosphor of the present invention has a phosphor film made of a conventional divalent metal fluorohalide phosphor using only europium as an activator. It has higher brightness than a radiation image conversion panel. As described above, the phosphor of the present invention is particularly useful as a phosphor for radiation image conversion panels, but the use of the phosphor of the present invention is not limited to this. That is, the phosphor of the present invention emits high-intensity near-ultraviolet to blue instantaneous light when excited by ionizing radiation, electron beams, vacuum ultraviolet rays, ultraviolet rays, etc., so it can be used in intensifying screens, cathode ray tubes, fluorescent lamps, etc. can be used. Furthermore, the phosphor of the present invention exhibits high-intensity thermal fluorescence when heated after being irradiated with ionizing radiation, electron beams, vacuum ultraviolet rays, ultraviolet rays, etc. and then heated, so it can be used in thermal fluorescence dosimeters, etc. be able to. As described above, the industrial utility value of the present invention is extremely large. Next, the present invention will be explained with reference to Examples. Example As shown in (1) to (18) below, each phosphor raw material was weighed out and thoroughly mixed using a ball mill.
Different types of phosphor raw material mixtures were prepared. (1) BaF ₂ 175.3g (1 mol), BaBr ₂・2H ₂ O333.2
g (1 mol), EuCl ₃ 0.052 g (0.0002 mol) and ZrO ₂ 0.024 g (0.0002 mol) (2) BaF ₂ 166.5 g (0.95 mol), BaF ₂ 1.4 g (0.05
mol), BaBr ₂・2H ₂ O333.2g (1 mol),
EuCl ₃ 0.052g (0.0002 mol) and ZrO ₂ 0.024
g (0.002 mol) (3) BaF ₂ 166.5 g (0.95 mol), MgF ₂ 3.1 g (0.05 mol)
mol), BaBr ₂・2H ₂ O333.2g (1 mol)
EuCl ₃ 0.052g (0.0002 mol) and ZrO ₂ 0.024
g (0.0002 mol) (4) BaF ₂ 166.5 g (0.95 mol), CaF ₂ 3.9 g (0.05 mol)
mol), BaBr ₂・2H ₂ O336.4g (1.01 mol),
EuCl ₃ 0.052g (0.0002 mol) and ZrO ₂ 0.024
g (0.0002 mol) (5) BaF ₂ 166.5 g (0.95 mol), SrF ₂ 6.3 g (0.05 mol)
mol), BaBr ₂・2H ₂ O336.4g (1.01 mol),
EuCl ₃ 0.077g (0.0003 mol) and ScCl ₃ 0.045
g (0.0003 mol) (6) BaF ₂ 166.5 g (0.95 mol), ZnF ₂ 5.2 g (0.05 mol)
mol), BaBr ₂・2H ₂ O333.2g (1 mol)
EuCl ₃ 0.052 g (0.0002 mol) and Sc ₂ O ₃ 0.028
g (0.0002 mol) (7) BaF ₂ 166.5 g (0.95 mol), CdF ₂ 7.5 g (0.05 mol)
mol), BaBr ₂・2H ₂ O333.1g (1 mol),
EuCl ₃ 0.052g (0.0002 mol) and ZrO ₂ 0.024
g (0.0002 mol) (8) BaF ₂ 175.3 g (1 mol), BaCl ₂・2H ₂ O244.2
g (1 mol), EuF ₃ 0.042 g (0.0002 mol) and ZrCl ₄ 0.047 g (0.0002 mol) (9) BaF ₂ 168.3 g (0.96 mol), BaF ₂ 1.12 g (0.04
mol), BaCl ₂・2H ₂ O244.2g (1 mol),
EuF ₃ 0.042g (0.0002mol) and Sc
(NO ₃ ) ₃ 0.069g (0.0003mol) (10) BaF ₂ 164.8g (0.94mol), MgF ₂ 3.7g (0.06
mol), BaCl ₂・2H ₂ O251.6g (1.03 mol),
EuF ₃ 0.042g (0.0002 mol) and ZrCl ₄ 0.070
g (0.0003 mol) (11) BaF ₂ 166.5 g (0.95 mol), SrF ₂ 6.3 g (0.05 mol)
mol), BaCl ₂ 2・H ₂ O249.1g (1.02 mol),
EuCl ₃ 0.077g (0.0003 mol) and ScCl ₃ 0.045
g (0.0003 mol) (12) BaF ₂ 168.3 g (0.96 mol), ZnF ₂ 4.14 g (0.04
mol), BaCl ₂・2H ₂ O249.1g (1.02 mol),
EuCl ₃ 0.077g (0.0003 mol) and ZrCl ₄ 0.047
g (0.0002 mol) (13) BaF ₂ 168.3 g (0.96 mol), CdF ₂ 6.02 g
(0.04 mol), BaCl ₂ 2H ₂ O2 39.4 g (0.98 mol), EuCl ₃ 0.077 g (0.0003 mol) and
Sc ₂ O ₃ 0.028g (0.0002 mol) (14) BaF ₂ 175.3g (1 mol), BaBr ₂ .
2H ₂ O319.6g (0.96 mol), BaI ₂・2H ₂ O21.6g
(0.05 mol), EuCl ₃ 0.129 g (0.0005 mol) and ZrCl ₄ 0.047 g (0.002 mol) (15) BaF ₂ 168.3 g (0.96 mol), BaF ₂ 1.12 g
(0.04 mol), BaBr ₂ 2H ₂ O 303.1g (0.91 mol), BaCl ₂ 2H _{2 O} 24.4g (0.1 mol),
EuF ₃ 0.104g (0.0005mol) and Sc
(NO ₃ ) ₃ 0.045g (0.0002mol) (16) BaF ₂ 164.8g (0.94mol), MgF ₂ 3.7g
(0.06 mol), BaBr _{2.2H 2} O322.8g (0.969 mol), BaI _2.2H 2 _O2 1.8g (0.051 mol),
EuF ₃ 0.104g (0.0005 mol) and ZrCl ₄ 0.047
g (0.0002 mol) (17) BaF ₃ 166.5 g (0.95 mol), SrF ₂ 6.3 g (0.05 mol)
mol), BaBr ₂ 316.4g (0.95 mol), BaCl ₂ .
_2H2O12.2g (0.05mol), _EuCl3 0.129g
(0.0005 mol) and ScCl ₃ 0.045 (0.0003 mol) (18) BaF ₂ 166.5 g (0.95 mol), ZnF ₂ 5.2 g (0.05 mol)
mol), BaCl ₂ 2H ₂ O231.9g (0.95 mol),
_Bal2・_2H2O21.4g (0.05mol), _EuCl3 0.129g
(0.0005 mol) and ZrO ₂ 0.062 g (0.0005 mol) Next, each of the above 18 types of phosphor raw material mixtures was packed into an alumina crucible and placed in an electric furnace, and the phosphor raw material mixtures (14), (16) and ( 18) Regarding 2
The phosphor raw material mixtures were fired at a temperature of 800° C. in a nitrogen gas atmosphere containing % of hydrogen gas, and the other phosphor raw material mixtures were fired at a temperature of 850° C. in a carbon atmosphere for 3 hours. After firing, the crucible was taken out of the electric furnace and rapidly cooled in air. The obtained fired product was pulverized and then passed through a sieve to make the particle size uniform, thereby obtaining a phosphor.
Each of the 18 types of phosphors produced in this way
After irradiating with 80KVp X-rays, these phosphors are excited and illuminated with 630nm light obtained by dividing the light emitted from a xenon lamp set in a spectrometer (Hitachi spectrophotometer MPF-2A model). The exhaust luminescence was measured. As a result, the stimulated luminescence brightness of these phosphors is higher than that of conventional europium-activated divalent metal fluorohalide fluorophores prepared using the same method except that no co-activator is used, as shown in the table below. The luminance was significantly higher than the stimulated luminance measured under the same conditions.

【table】

[Table] Next, for each of the above 18 types of phosphors of the present invention, 8 parts by weight of the phosphor and 1 part by weight of nitrified cotton were mixed using a solvent (mixture of acetone, ethyl acetate, and butyl acetate). A phosphor coating solution with a viscosity of 50 centistokes was prepared. Next, this coating solution was applied uniformly onto a horizontally placed polyethylene terephthalate film (support) using a knife coater, and dried at 50°C until the layer thickness was approximately 300°C.
A phosphor layer of μ is formed, then an acetone solution of cellulose acetate is uniformly applied on this phosphor layer, and dried to form a transparent protective film with a layer thickness of approximately 8 μ. A radiation image conversion panel was fabricated. Separately, for comparison, the conventional europium-activated divalent metal fluorohalide phosphor was used.
A radiation image conversion panel was produced in the same manner as above. Sensitivity of the radiation image conversion panels of the present invention thus obtained (photosensitivity when excited with He-Ne laser light (633 nm) after irradiating each radiation image conversion panel with X-rays with a tube voltage of 80 KVp) As with the comparison of the stimulated luminance of the phosphors in the table above, the luminance of the conventional europium-activated divalent metal fluorohalide phosphor prepared for comparison The cost was higher than that of a radiation image conversion panel having a light layer.

[Brief explanation of the drawing]

FIG. 1 is a graph illustrating the stimulated emission spectrum of the phosphor of the present invention. FIG. 2 is a graph illustrating the relationship between the amount of coactivator (Z value) and the stimulated luminance in the phosphor of the present invention.

Claims (1)

[Claims] 1. The compositional formula is (B _a1-x , M〓 _x )F ₂ ·aBaX ₂ : yEu, zA (where M〓 is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium) species, X is at least one of chlorine, bromine and iodine, A is at least one of zirconium and scandium, and a, x, y and z are each 0.5≦a≦
1.25, 0≦x≦1, ^{10 -6} ≦y≦2×10 ^-1 and 0
A divalent metal fluorohalide phosphor represented by <z≦ ^10-2 ). 2. The divalent metal fluorohalide phosphor according to claim 1, wherein y is a number satisfying the condition 10 ^-5 ≦y≦10 ^-2 . 3. Divalent metal fluorohalide fluorescence according to claim 1 or 2, wherein z is a number satisfying the condition 5×10 ^-6 ≦z≦5×10 ^-3 body. 4. In a radiation image conversion panel having a phosphor layer made of a photostimulable phosphor, the above-mentioned photostimulable phosphor has a compositional formula (B _a1-x , M〓 _x )F ₂ · aBaX ₂ : yEu, zA (However, M is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, and A is at least one of zirconium and scandium. , a, x, y and z are each 0.5≦a≦
1.25, 0≦x≦1, 10 ^-6 <y≦2×10 ^-1 and 0
A radiation image conversion panel comprising a divalent metal fluorohalide phosphor represented by <z≦10 ^-2 . 5. The radiation image conversion panel according to claim 4, wherein y is a number satisfying the condition 10 ^-5 ≦y≦10 ^-2 . 6. The radiation image conversion panel according to claim 4 or 5, wherein z is a number satisfying the following condition: 5×10 ⁻⁶ ≦z≦5×10 ⁻³ .