JP2640021B2 - Radiation image conversion panel and radiation image reproduction method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radiation image conversion panel having a support and a phosphor layer made of a stimulable phosphor provided on the support, and a radiation image. The present invention relates to a method for reproducing a radiation image recorded on a conversion panel. More specifically,
The present invention provides a method of irradiating one side with excitation light, extracting photostimulated light (stimulated light) from both sides, and reproducing a radiation image,
And a radiation image conversion panel which is advantageously used in the radiation image reproducing method.

[Background of the Invention] As one of the alternatives to radiography using a silver halide photosensitive material, a radiation image conversion method using a stimulable phosphor has recently attracted attention. This radiation image conversion method uses a radiation image conversion panel (stimulable phosphor sheet) having a stimulable phosphor.
The radiation transmitted through the subject or the radiation emitted from the subject is absorbed by the stimulable phosphor of the panel, and then the stimulable phosphor is converted into an electromagnetic wave selected from visible light and infrared light. (Excitation light), the radiation energy accumulated in the stimulable phosphor is emitted as fluorescence (stimulation light) by exciting the stimulable phosphor in a time-series manner. This is a method of obtaining signals and imaging the obtained electric signals.

According to the above-described radiation image conversion method, there is an advantage that a radiographic image with a large amount of information can be obtained with a much smaller exposure dose than in the case of the conventional radiographic method. Therefore, this radiation image conversion method is very useful especially in direct medical radiography such as X-ray radiography for medical diagnosis.

The radiation image conversion panel used in the above-described radiation image conversion method has, as a basic structure, a support and a phosphor layer provided on one surface thereof. In general, a transparent protective film is provided on the surface of the phosphor layer opposite to the support (the surface not facing the support) so that the phosphor layer is chemically altered or physically changed. Protection from shocks.

The phosphor layer is composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. The stimulable phosphor absorbs radiation such as X-rays, and then emits visible light, It has a property of emitting light (stimulated emission) when irradiated with electromagnetic waves such as infrared rays. Therefore, the radiation transmitted through the subject or emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and the radiation image of the subject or the subject is displayed on the radiation image conversion panel. Are formed as an accumulated image of radiation energy. This accumulated image can be emitted as stimulating light (fluorescence) by being excited by electromagnetic waves (excitation light) such as visible light and infrared light, and the stimulating light is photoelectrically read and converted into an electric signal. This makes it possible to image (reproduce) a stored image of radiation energy.

In the step of reproducing a recorded radiation image (accumulated image) from a radiation image conversion panel using the stimulable phosphor described above, radiation is usually applied from the surface side of the phosphor layer (the side opposite to the side where the support is provided). A method has been used in which an image conversion panel is irradiated with excitation light, stimulating light generated by the excitation light is extracted from the surface on the excitation light irradiation side, and the image is read photoelectrically.

On the other hand, in order to more effectively or diversify the use of a radiation image stored as an energy image having image information in the phosphor layer of the radiation image conversion panel, a radiation image reproducing method for extracting stimulating light from both sides of the panel. Is also known.
That is, in the ordinary radiation image reproducing method, of the energy stored in the phosphor layer, the radiation energy stored in the front surface portion of the phosphor layer is mainly used, and the deep region of the phosphor layer, that is, the support side (back surface) is used. The radiation energy stored in (side) is hardly used. However, the image information (radiation energy image) recorded on the front surface of the phosphor layer and the image information recorded on the back surface thereof have radiation image information of different energies.
In other words, the relatively low-energy radiation is efficiently absorbed by the phosphor layer on the front surface side, so that a radiation image with a relatively low energy is recorded. Since low-energy radiation is absorbed, a relatively high-energy radiation image is recorded. By utilizing this, image processing such as so-called “energy subtraction processing” can be performed, and the obtained information can be further processed. It can be used effectively.

Further, since the beam diameter of the stimulating excitation light (laser light) on the back side of the phosphor is substantially larger than that on the back side due to scattering, the information of the phosphor layer on the front side is used as a normal image, The information of the body layer can be used as a blurred image for so-called “blurred mask processing”. In any case, in order to effectively perform these processes, it is important to extract information from the front-side phosphor layer and the back-side phosphor layer with good separation.

For the above reasons, the support is formed from a transparent material so that the photostimulable light is easily transmitted, and the photostimulable light is extracted not only from the front side of the radiation image conversion panel but also from the back side (the support side). Proposals to try have already been made. However, in this method, the photostimulated light that is extracted on either side includes the photostimulated light generated on the side from which the photostimulated light is extracted, and the photostimulated light that is generated on the opposite side and is scattered within the phosphor layer. Since the photostimulated light reaching the side is mixed, the radiation image recorded on the phosphor layer on each side and the radiation image recorded on the opposite phosphor layer are not separated well, and the image processing However, there is a problem that it is difficult to obtain useful image information.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 60-262099 proposes that a plurality of stimulable phosphor layers are provided and an excitation light blocking layer is provided between the stimulable phosphor layers. It has been done. The addition of the excitation light blocking layer enables the reproduction of a radiation image with completely separated information on both sides of the phosphor layer, but on the other hand, the excitation light must be irradiated from the screen. Operational problems occur on the device.
Further, the method cannot be applied to the blur mask processing.

[Object of the Invention] An object of the present invention is to provide a radiation image conversion panel having a novel support and a phosphor layer made of a stimulable phosphor provided on the support.

Further, the present invention provides a method of irradiating one side with excitation light, extracting stimulating light from both sides to reproduce a radiation image, and a radiation image conversion panel advantageously used in the radiation image reproducing method. With the goal.

[Summary of the Invention] The present invention relates to a radiation image conversion panel having a transparent support and a phosphor layer provided on the support and comprising a binder containing and supporting stimulable phosphor particles in a dispersed state. ,
The phosphor layer is a surface-side phosphor layer, an intermediate in which stimulable phosphor particles having an average particle diameter smaller than the average particle diameter of the stimulable phosphor particles present in the surface-side phosphor layer are arranged. A region phosphor layer, and a backside phosphor layer on which stimulable phosphor particles having an average particle diameter larger than the average particle diameter of the stimulable phosphor particles present in the intermediate region phosphor layer are arranged. A radiation image conversion panel characterized in that:

The present invention also provides a radiation image conversion panel having a transparent support and a phosphor layer made of stimulable phosphor particles provided on the support, wherein the phosphor layer is a front-side phosphor layer. An intermediate layer that transmits excitation light for extracting photostimulated light from the radiation image conversion panel, and blocks transmission of photostimulated light, and a radiation image conversion panel including a backside phosphor layer. is there.

Any of the above radiation image conversion panels of the present invention, the radiation image conversion panel, irradiates the excitation light to one surface, the stimulating light generated from the phosphor layer by the irradiation of the excitation light,
A method of reproducing a radiation image recorded on a radiation image conversion panel, comprising photoelectrically reading from both sides of the radiation image conversion panel to obtain an electronic signal, and then performing image processing by combining the electric signals obtained from both sides. It can be used advantageously.

[Configuration of the Invention] The first representative example of the configuration of the radiation image conversion panel of the present invention is as follows.
2 and 3 show.

FIG. 1 shows a radiation image conversion panel having a transparent support 11, a phosphor layer 12 made of a binder containing and supporting stimulable phosphor particles in a dispersed state, and a protective film 13. In the phosphor layer 12, the surface-side phosphor layer 12a, stimulable phosphor particles having an average particle diameter smaller than the average particle diameter of the stimulable phosphor particles present in the surface-side phosphor layer 12a are arranged. Intermediate region phosphor layer 12b, and a backside phosphor layer on which stimulable phosphor particles having an average particle diameter larger than the average particle diameter of the stimulable phosphor particles present in intermediate region phosphor layer 12b are arranged. 12c
Having a configuration consisting of:

FIG. 2 shows a radiation image conversion panel having a transparent support 21, a phosphor layer 22 made of a binder containing and supporting stimulable phosphor particles in a dispersed state, and a protective film 23. Phosphor layer
Numeral 12 includes an upper phosphor layer 22d and a lower phosphor layer 22e.
Both the upper phosphor layer 22d and the lower phosphor layer 22e are such that the phosphor particles have a smaller (or larger) particle diameter from one side to the other along the depth direction. They are arranged with a gentle gradient. Then, the two phosphor layers are joined such that the smaller particle diameter sides of the phosphor layers face each other. By this method, an intermediate region phosphor layer having a smaller particle diameter than either region on both sides is formed at the center.

FIG. 3 shows a radiation image conversion panel having a transparent support 31, a phosphor layer 32 made of a binder containing and supporting stimulable phosphor particles in a dispersed state, and a protective film 33. Phosphor layer
33 is a front side phosphor layer 32f, an intermediate layer 32g that transmits excitation light for extracting stimulating light from the radiation image conversion panel, and blocks transmission of stimulating light, and a back side phosphor layer 32h.
Consists of In the radiation image conversion panel shown in FIG. 3, the phosphor layer 32 is a phosphor layer formed without using a binder (binder), for example, a stimulable phosphor layer formed by evaporation, Other stimulable phosphor layers may be used, such as a stimulable phosphor layer formed by sintering, or a stimulable phosphor layer formed by sintering impregnated with a polymer.

Each of FIGS. 1, 2 and 3 shows a basic configuration of the radiation image conversion panel. The radiation image conversion panel of the present invention is not limited to the above-described configuration. For example, radiation image conversion panels having various configurations such as providing an undercoat layer between arbitrary layers are possible.

The radiation image conversion panel of the present invention having the above configuration can be manufactured, for example, by the following method.

First, the manufacture of the radiation image storage panel shown in FIG. 1 will be described.

This radiation image conversion panel discloses a radiation image conversion panel in which phosphor layers having different particle diameters (average particle diameters) of stimulable phosphors contained therein are different from each other, together with a method for producing the same. It can be manufactured using techniques such as various materials and a method for manufacturing a phosphor layer described in the gazette.

The support is transparent in order to transmit the generated photostimulated light (and in some cases also to transmit the excitation light). Examples of such materials include films of plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, and the like. In order to strengthen the bond between the support and the support and the phosphor layer, a polymer substance such as gelatin may be applied to the surface of the support on the side where the phosphor layer is provided to form an adhesion-imparting layer.

A phosphor layer is formed on the support. The phosphor layer is basically a layer made of a binder that contains and supports the stimulable phosphor particles in a dispersed state. In the radiation image conversion panel of FIG. 1, the phosphor layer is composed of three layers: a front side phosphor layer, an intermediate region phosphor layer, and a back side phosphor layer.

The stimulable phosphor is a phosphor that emits stimulable light when irradiated with excitation light after irradiating radiation as described above, but from a practical aspect, the wavelength is in the range of 400 to 800 nm. It is desirable that the phosphor be a phosphor that shows stimulated emission in a wavelength range of 300 to 500 nm by the excitation light. Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include StS: C described in U.S. Pat.No. 3,859,527.
e, Sm, SrS: Eu, Sm, ThO 2: Er, and _{La 2 O 2 S: Eu,} Sm, are described in JP-A-55-12142 ZnS: Cu, Pb,
BaO.xAl ₂ O ₃ : Eu (where 0.8 ≦ x ≦ 10) and M ^II
O.xSiO ₂ : A (where M ^II is Mg, Ca, Sr, Zn, Cd, or Ba, and A is Ce, Tb, Eu, Tm, Pb, Tl, Bi, or
Mn, and x is 0.5 ≦ x ≦ 2.5), which is described in JP-A-55-12143 (Ba _1-xY , M
g _x , Ca _y ) FX: aEu ²⁺ (where X is at least one of Cl and Br, x and y are 0 <x + y ≦ 0.6,
And xy ≠ 0, a is 10 ⁻⁶ ≦ a ≦ 5 × 10 ⁻² ), and LnOX: xA described in JP-A-55-12144 (where Ln is La, Y, Gd and at least one of Lu, X is at least one of Cl and Br, A is at least one of Ce and Tb, and x is 0 <x
<0.1), described in JP-A-55-12145 (Ba _1-x , M ²⁺
_x ) FX: yA (where M ²⁺ is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br and I, A is Eu, Tb, Ce , Tm, Dy, Py, Ho, Nd,
At least one of Yb and Er, and x is 0
.Ltoreq.x.ltoreq.0.6, y is 0.ltoreq.y.ltoreq.0.2), M ^II FX.xA described in JP-A-55-160078:
yLn [where M ^II is at least one of Ba, Ca, Sr, Mg, Zn, and Cd; A is BeO, MgO, CaO, SrO, BaO, Z
nO, Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , G
_{eO 2, SnO 2, Nb 2} O 5, Ta 2 O 5, and at least one of ThO _2, Ln is Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb,
At least one of Er, Sm, and Gd, X is Cl, B
at least one of r and I, wherein x and y are respectively 5 × 10 ⁻⁵ ≦ x ≦ 0.5 and 0 <y ≦ 0.2]. No. 116777 (Ba _1-x , M
^{_{II x) F 2 · aBaX 2}} : yEu, zA [ provided that at least one of the at least one of M ^II is beryllium, magnesium, calcium, strontium, zinc and cadmium,, X is 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 <z ≦ 10 ⁻²
And a phosphor represented by the composition formula (Ba _1-x , M ^II).
_{x) F 2 · aBaX 2:} yEu, zB [ provided that at least one of the M ^II is beryllium, magnesium, calcium, strontium, zinc and cadmium,, X is chlorine, bromine,
And at least one of iodine and a, x,
y and z are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 1
0 ⁻⁶ ≦ y ≦ 2 × 10 ⁻¹ and 0 <z ≦ 2 × 10 ⁻¹ ]
A phosphor represented by the following composition formula is described in JP-A-57-23675 (Ba _1-x , M ^II
_x ) F ₂ .aBaX ₂ : yEu, zA [where M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc and cadmium, X is at least one of chlorine, bromine and iodine, A Is at least one of arsenic and silicon, and a, x, y and z are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦
y ≦ 2 × 10 ⁻¹ and 0 <z ≦ 5 × 10 ⁻¹ ], and M ^III OX: xCe described in JP-A-58-69281.
[However, M ^III is Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, E
at least one trivalent metal selected from the group consisting of r, Tm, Yb, and Bi, X is one or both of Cl and Br, and x is 0 <x <0.1] A phosphor represented by the following formula: Ba _1-x M _{x / 2} described in JP-A-58-206678.
L _{x / 2} FX: yEu ²⁺ [where M is Li, Na, K, Rb, and C
s represents at least one alkali metal selected from the group consisting of s; L is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and T
X represents at least one trivalent metal selected from the group consisting of l; X represents at least one halogen selected from the group consisting of Cl, Br, and I; and x represents 10 ^-2
.Ltoreq.x.ltoreq.0.5, y is 0 <y.ltoreq.0.1]. BaFX.xA: yE described in JP-A-59-27980.
u ²⁺ [where X is at least one halogen selected from the group consisting of Cl, Br and I; A is a calcined product of a tetrafluoroborate compound; and x is 10 ^−6.
.Ltoreq.x.ltoreq.0.1, y is 0 <y.ltoreq.0.1], BaFX.xA: yE described in JP-A-59-47289.
u ²⁺ [where X is at least one halogen selected from the group consisting of Cl, Br and I; A is monovalent or divalent hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid] A calcined product of at least one compound selected from the group of hexafluoro compounds consisting of salts of valent metals; and x is 10 ⁻⁶ ≦ x ≦
0.1, y is 0 <y ≦ 0.1], and BaFX.xNa described in JP-A-59-56479.
X ′: aEu ²⁺ [where X and X ′ are Cl, B
r and at least one of I, and x and a are respectively 0 <x ≦ 2 and 0 <a ≦ 0.2]
A phosphor represented by the following composition formula: M ^II FXxNa described in JP-A-59-56480
X ′: yEu ²⁺ : zA [where M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X ′ are Cl, Br, and I, respectively. At least one halogen selected from the group consisting of: A
Is at least one transition metal selected from V, Cr, Mn, Fe, Co, and Ni; and x is 0 <x ≦ 2,
y is 0 <y ≦ 0.2, and z is 0 <z ≦ 10 ^-2 a] phosphor represented by a composition formula of, M ^II FX · aM that is described in JP-A-59-75200
^I X ′ ・ bM ′ ^II X ″ ₂・ cM ^III X ₃・ xA: yEu ²⁺ [However, M
^II is Ba, Sr, and is at least one alkaline earth metal selected from the group consisting of Ca; M ^I is Li, Na, K, R
b, and at least one alkali metal selected from the group consisting of Cs; M ′ ^II is at least one divalent metal selected from the group consisting of Be and Mg; M ^III is Al, G
a, In, and at least one trivalent metal selected from the group consisting of Tl; A is a metal oxide; X is Cl, Br,
X ', X ", and X are at least one halogen selected from the group consisting of F, Cl, Br, and I; and a is 0 ≦ a ≦ 2, b is 0 ≦ b ≦ 1
0 ^-2 , c is 0 ≦ c ≦ 10 ⁻² , and a + b + c ≧ 10 ⁻⁶ ;
x is 0 <x ≦ 0.5, y is 0 <y ≦ 0.2], and M ^II X ₂ · aM ^II described in JP-A-60-84381.
X ₂ : xEu ^{2+ wherein} M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X and X ′ are selected from the group consisting of Cl, Br, and I A stimulable phosphor represented by a composition formula of at least one halogen and X 、 X ′; and a is 0.1 ≦ a ≦ 10.0 and x is 0 <x ≦ 0.2. M ^II FX ・ aM ^I described in JP-A-60-101173
X ′: xEu ²⁺ [where M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca;
^I is at least one alkali metal selected from the group consisting of Rb and Cs; X is at least one halogen selected from the group consisting of Cl, Br and I; X 'is F,
At least one halogen selected from the group consisting of Cl, Br and I; and a and x are each 0 ≦ a
≦ 4.0 and 0 <x ≦ stimulable phosphor represented by a composition formula of 0.2 and is, is described in Japanese Patent Application No. Sho 60-70484 Pat of the applicant M ^I X: xBi [However, M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X is C
at least one halogen selected from the group consisting of l, Br and I; and x is a numerical value in the range of 0 <x ≦ 0.2]. And alkali metal halide phosphors described in 72087 and JP-A-61-72088.

Further, M described in JP-A-60-84381 described above
^II X ₂・ aM ^II X ₂ : xEu ²⁺ stimulable phosphor may contain the following additives at the following ratio per mole of M ^II X ₂・ aM ^II X ′ ₂ : Good.

BM ^I X "described in JP-A-60-166379 (where M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X" represents F, Cl, Br and I
At least one halogen selected from the group consisting of: and b is 0 <b ≦ 10.0);
No. 83, bKX ″ · cMgX ₂ · dM ^III X ′
₃ (where M ^III is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu, and X ″,
X and X ′ are each at least one halogen selected from the group consisting of F, Cl, Br and I, and b, c and d are respectively 0 ≦ b ≦ 2.0, 0 ≦ c ≦ 2.
0, 0 ≦ d ≦ 2.0 and 2 × 10 ⁻⁵ ≦ b + c + d); yB described in JP-A-20-228592
(However, y is 2 × 10 ⁻⁴ ≦ y ≦ 2 × 10 ⁻¹ );
BA described in JP-A-60-228593 (where A is Si
At least one oxide selected from the group consisting of O ₂ and P ₂ O ₅ , and b is 10 ⁻⁴ ≦ b ≦ 2 × 10 ⁻¹ ); described in JP-A-61-120883. BSiO
(However, b is 0 <b ≦ 3 × 10 ^-2 );
BSnX ″ ₂ described in JP120885 (where X ″
Is at least one halogen selected from the group consisting of F, Cl, Br and I, and b is 0 <b ≦ 10 ^-3 ); bCsX ″ described in JP-A-61-235486.
CSnX ₂ (where X ″ and X are F, Cl,
At least one halogen selected from the group consisting of Br and I, and b and c are each 0 <b ≦
10.0 and 10 ⁻⁶ ≦ c ≦ 2 × 10 ⁻² );
Is described in -235,487 JP bCsX "· yLn ³⁺ (However, X" is at least one halogen selected from the group consisting of F, Cl, Br and I, Ln is Sc, Y, Ce, P
r, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are at least one rare earth element selected from the group consisting of Lu and b and y are respectively 0 <b ≦ 10.0 and
10 ⁻⁶ ≦ y ≦ 1.8 × 10 ⁻¹ ).

Particularly preferred phosphors described in _{JP-A-63-101478 (Ba 1-a, M} II a) F (Br 1-b, I b) · cNaX · dCs
X ′ · eA: xEu ²⁺ [where M ^II is Sr or Ca, X and X ′
Are Cl, Br or I, respectively, A is Al ₂ O ₃ , SiO ₂ or Z
rO ₂ , a, b, c, d, e and x are each 0 <a ≦
0.5, 0 <b <1, 0 <c ≦ 2, 5 × 10 ⁻⁵ ≦ d ≦ 5 × 10
^-2 , 5 × 10 ⁻⁵ ≦ e ≦ 0.5 and 0 <x ≦ 0.2].

Among the above stimulable phosphors, a divalent europium-activated alkaline earth metal halide-based phosphor and a rare earth element-activated rare earth oxyhalide-based phosphor are particularly preferable because they exhibit high-luminance stimulable light emission. However, the stimulable phosphor used in the present invention is not limited to the above-described phosphors, and any phosphor can be used as long as it exhibits stimulable emission when irradiated with radiation and then irradiated with excitation light. There may be.

In the radiation conversion panel of the present invention, the stimulable phosphors are arranged such that the average particle diameter of the stimulable phosphor is large on both surface sides and small in the intermediate region. The average particle size of the phosphor particles on both surface sides is preferably in the range of 2 to 50 μm, and particularly preferably in the range of 5 to 2 μm. On the other hand, the average particle diameter of the phosphor particles in the middle region is 0.5 to 10 μm
, And particularly preferably in the range of 1 to 5 μm. The difference between the average particle diameter of the phosphor particles and the average particle diameter of the phosphor particles in the intermediate region is usually provided at 1 μm or more, preferably 2 to 10 μm, on both surface sides. The average particle diameter on both surfaces may be the same or different.

In addition, the thickness of the phosphor layer portion on both surface sides is 30 to
It is preferably in the range of 200 μm, especially 50 to 150 μm
m is preferably in the range. The intermediate region preferably has a thickness in the range of 10 to 100 μm, particularly preferably in the range of 10 to 50 μm.

Examples of the binder for the phosphor layer include proteins such as gelatin, polysaccharides such as dextran, and natural high molecular substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride, and the like. Vinyl chloride copolymer,
Bonds represented by synthetic polymers such as polymethyl methacrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, (meth) acrylate / (meth) acrylonitrile copolymer, polyvinyl alcohol, and linear polyester Agents can be mentioned.

The phosphor layer can be formed on the support by the following method, for example.

First, a stimulable phosphor and a binder are added to an appropriate solvent and mixed well to prepare a coating solution in which phosphor particles are uniformly dispersed in a binder solution. Coating on top to form a coating. Next, the formed coating film is dried by gradually heating to complete the formation of the first phosphor layer (backside phosphor layer) on the support. Then, on this first phosphor layer, a second phosphor layer (intermediate region phosphor layer) is formed in a similar manner, and a third phosphor layer (front surface phosphor) is further formed in a similar manner. By forming the layer, a phosphor layer having a desired configuration can be obtained.

It should be noted that each phosphor layer does not necessarily need to be formed by directly applying a coating liquid sequentially as described above. For example, the coating liquid is separately applied to a sheet such as a glass plate, a metal plate, or a plastic sheet. After the phosphor layer is formed by drying, the phosphor layer is pressed onto the support or another phosphor layer, or an adhesive is used to form the support and the phosphor layer, or between the phosphor layers. May be joined.

Furthermore, each phosphor layer may be colored with a colorant that selectively absorbs excitation light for the purpose of improving the sharpness of an image.

A transparent protective film for physically and chemically protecting the phosphor layer is provided on the surface of the phosphor layer. The thickness of the transparent protective film is desirably about 3 to 20 μm.

Next, a method of manufacturing the radiation image conversion panel having the configuration shown in FIG. 2 will be described.

In the phosphor layer having a particle diameter gradient shown in FIG. 2, for example, after a coating solution containing a stimulable phosphor and a binder is applied to a temporary support, large particles first settle to the bottom side. As described above, the coating film is dried and cured under slow conditions to form two phosphor films in which the particle diameter gradient is formed in one direction in advance. It can be manufactured using a method of joining face to face. The selection and preparation of each material of the phosphor layer, the support, the protective film, and the like are the same as in the case of manufacturing the radiation image conversion panel of FIG.

In addition, as is clear from the configuration of the radiation image conversion panel shown in FIG. 2, the division of the phosphor layer of the radiation image conversion panel of the present invention is performed in such a manner that the phosphor layers in each area are independent and distinct. It does not mean that they can be separated. In addition, each area can be further divided as necessary.

Next, a radiation image conversion panel having the configuration shown in FIG. 3 will be described.

The phosphor layer of the radiation image conversion panel having the structure shown in FIG. 3 has the same structure as that shown in FIGS. 2
It can be manufactured in the same manner as the phosphor layer shown in the figure. In addition,
As described above, the phosphor layer may be formed by another method such as vapor deposition or sintering, and a method of forming the phosphor layer using such a method is already known.

Examples of the intermediate layer having the above transmission and reflection characteristics include a multilayer filter such as a dichroic filter.

The multilayer filter is formed by sequentially laminating two or more substances having different refractive indexes with a thickness of about 1 of the wavelength of light. Various materials used for known optical thin films can be used for the multi-layer filter.
Examples include low refractive index substances such as O ₂ and MgF ₂ and high refractive index substances such as TiO ₂ , ZrO ₂ and ZnS.

The multilayer filter is provided by, for example, forming a thin film composed of the above substances by laminating several to several tens of layers on the surface of a transparent substrate such as a glass plate by a method such as vacuum deposition, sputtering, or ion plating. it can. Note that the ion plating method is a preferable method in the case where a substrate is made of a polymer substance, since a filter having high adhesion to the substrate can be formed without raising the temperature of the substrate.

By controlling the substance (refractive index) used and the thickness of each layer in the production of the multilayer filter, various filters having the above characteristics can be obtained in accordance with the stimulable phosphor to be used. Generally, the thickness of the entire multilayer filter is in the range of about 0.1 to 10 μm.

That is, in the manufacturing process of the radiation image conversion panel as described above, the radiation image conversion panel shown in FIG. 3 can be manufactured by manufacturing the multilayer filter so as to be interposed between the phosphor layers.

FIG. 4 is a schematic view showing a method of reproducing an image from the radiation image conversion panel of the present invention.

That is, the excitation light source 41 is arranged on one side of the radiation image conversion panel 40 of the present invention, and the excitation light source irradiates the radiation image conversion panel with excitation light. The irradiation of the excitation light excites the phosphor of the radiation image conversion panel to generate photostimulated light. Then, the photostimulated luminescence is detected by photostimulated photodetectors 42a and 42b arranged on both sides of the radiation image conversion panel.
Detected from both sides, photoelectrically converted by a known method to obtain a radiation image. In addition, the excitation system of the radiation image conversion panel and the photostimulation device, the photoelectric conversion device, and the reproduction system until reproducing the radiation image are already known, and even when the radiation image reproduction method of the present invention is performed, Since a known device can be used, a detailed description is omitted here.

[Effects of the Invention] When a radiation image reproducing method is performed using the radiation image conversion panel of the present invention, a radiation image is emitted from both sides (front side and back side) of the radiation image conversion panel by irradiation of excitation light from one side. Since they are taken out with a high degree of separation from each other, the image information obtained from the front side and the image information obtained from the back side are appropriately combined to enable various kinds of image processing operations such as energy subtraction processing and blur mask processing. Thus, useful image information can be obtained.

 Next, examples of the present invention and comparative examples will be described.

Example 1 Two types of stimulable divalent europium-activated barium fluorobromide phosphors (BaFBr: Eu ²⁺ ) having different average particle diameters, that is, each having an average particle diameter of 8 μm (phosphor I) ) And 2.
Two types of stimulable phosphors of 5 μm (phosphor II) were prepared.

Production of Radiation Image Conversion Panel Toluene and ethanol were added to a mixture of phosphor I and polyurethane to prepare a dispersion containing phosphor particles in a dispersed state. Next, tricresyl phosphate is added to the dispersion, and the mixture is sufficiently stirred and mixed using a propeller mixer to uniformly disperse the phosphor particles. The mixing ratio between the binder and the phosphor is 1:20 (weight Ratio) and viscosity 25-35PS
(25 ° C.) was prepared.

Next, a transparent polyethylene terephthalate film (support, thickness: 250 μm) horizontally placed on a glass plate, and a coating solution was uniformly applied thereon using a doctor blade. After the application, the support on which the coating film was formed was placed in a dryer, and the temperature inside the dryer was gradually increased from 25 ° C to 100 ° C, and the coating film was dried. Thus, a phosphor layer (first phosphor layer) having a layer thickness of 80 μm was formed on the support.

Next, methyl ethyl ketone was added to a mixture of the phosphor II and the linear polyester resin, and nitrocellulose having a nitrification degree of 11.5% was further added to prepare a dispersion containing phosphor particles in a dispersed state. Next, tricresyl phosphate, n-butanol, and methyl ethyl ketone are added to the dispersion, and the mixture is sufficiently stirred and mixed using a propeller mixer to uniformly disperse the phosphor particles and mix the binder and the phosphor. Ratio 1:20 (weight ratio) and viscosity 25-35PS (25 ° C)
Was prepared.

This coating solution was applied on the first phosphor layer previously formed by the same operation as described above to form a phosphor layer (second phosphor layer) having a thickness of 30 μm.

Next, the same coating solution as that used in the production of the first phosphor layer is applied on the second phosphor layer by the same operation, and dried to form a phosphor layer having a thickness of 80 μm (third phosphor layer). Body layer).

A transparent protective film of polyethylene terephthalate (thickness: 12 μm, to which a polyester-based adhesive has been applied) is placed on the third phosphor layer with the adhesive layer side facing down, thereby bonding the transparent protective film. Then, a radiation image conversion panel comprising a support, a first phosphor layer, a second phosphor layer, a third phosphor layer, and a transparent protective film was manufactured.

Example 2 A first phosphor layer was formed on a support in the same manner as in Example 1.

Separately, a dichroic filter that transmits the excitation wavelength (632.8 nm) and reflects the stimulating light (peak wavelength: 390 nm) is placed horizontally, and the same coating solution as the first phosphor layer coating solution is uniformly applied thereon. A second phosphor layer having a thickness of 80 μm was formed in the same manner.

Next, on the support with the first phosphor layer manufactured earlier, on the first phosphor layer, a dichroic filter with a second phosphor layer was bonded such that the dichroic filter was in contact with the first phosphor layer. . Next, a protective film is similarly provided on the second phosphor layer, and a radiation image conversion panel including a support, a first phosphor layer, a dichroic filter layer, a second phosphor layer, and a transparent protective film is provided. Was manufactured.

Comparative Example 1 The same operation as in Example 1 was carried out except that the third phosphor layer was formed directly on the first phosphor layer without forming the second phosphor layer, and the particle diameter was relatively intermediate. A comparative radiation image conversion panel was manufactured without any intervening small phosphor particle regions.

Evaluation of Radiation Image Conversion Panel Each radiation image conversion panel manufactured as described above was evaluated by the sensitivity test described below.

After irradiating the radiation image conversion panel with X-rays having a tube voltage of 80 KVp, the radiation image conversion panel is irradiated with He
Excitation of the phosphor by scanning with -Ne laser light (wavelength: 632.8 nm), stimulated emission emitted from the phosphor layer,
Light was received by light receivers (photomultiplier tubes having a spectral sensitivity of S-5) arranged on both sides of the radiation image conversion panel, and the photostimulated light intensity on each side was separately measured.

Table 1 shows the contribution of each layer to the measured photostimulated intensity on both sides of the radiation image storage panel. The higher the contribution ratio, the higher the degree of separation of photostimulated light, and the more easily useful image information can be obtained.

Contribution ratio I: The proportion of the stimulated emission measured on the front side, of the stimulated emission on the front side phosphor layer. If the contribution ratios I and II are both 100%, all the stimulated emission from the front-side phosphor layer is measured on the front side, while all the stimulated emission from the back side is on the back side. , Which means that the information of the phosphor layers on the front side and the back side is completely separated.

[Brief description of the drawings]

FIGS. 1, 2, and 3 are schematic views showing examples of the configuration of the radiation image conversion panel according to the present invention. FIG. 4 is a schematic diagram for explaining the radiation image reproducing method of the present invention. 11,21,31: Support 12,22,32: Phosphor layer 12a, 12b, 12c, 22d, 22e, 22f, 22h: Phosphor layer 22g: Excitation light transmission / stimulated light shielding layer 13,23,33 : Protective film 40: Radiation image conversion panel 41: Excitation light source 42a, 42b: Stimulation detector

Claims (4)

(57) [Claims] 1. A radiation image conversion panel comprising a transparent support and a phosphor layer provided on the support and comprising a binder containing and supporting stimulable phosphor particles in a dispersed state,
The phosphor layer is a surface-side phosphor layer, an intermediate in which stimulable phosphor particles having an average particle diameter smaller than the average particle diameter of the stimulable phosphor particles present in the surface-side phosphor layer are arranged. A region phosphor layer, and a backside phosphor layer on which stimulable phosphor particles having an average particle diameter larger than the average particle diameter of the stimulable phosphor particles present in the intermediate region phosphor layer are arranged. A radiation image conversion panel, characterized in that: 2. A radiation image conversion panel comprising a transparent support and a phosphor layer provided on the support and comprising a binder containing and supporting stimulable phosphor particles in a dispersed state,
The phosphor layer is a surface-side phosphor layer, an intermediate in which stimulable phosphor particles having an average particle diameter smaller than the average particle diameter of the stimulable phosphor particles present in the surface-side phosphor layer are arranged. A region phosphor layer, and a backside phosphor layer on which stimulable phosphor particles having an average particle diameter larger than the average particle diameter of the stimulable phosphor particles present in the intermediate region phosphor layer are arranged. Irradiating one surface of the radiation image conversion panel with excitation light,
The photostimulation generated from the phosphor layer by the irradiation of the excitation light is photoelectrically read from both sides of the radiation image conversion panel to obtain electric signals, and then image processing is performed by combining the electric signals obtained from both sides. A method for reproducing a radiation image recorded on a radiation image conversion panel. 3. A radiation image conversion panel having a transparent support and a phosphor layer made of a stimulable phosphor provided on the support, wherein the phosphor layer is a surface-side phosphor layer, A radiation image conversion panel comprising an intermediate layer that transmits excitation light for extracting photostimulated light from the radiation image conversion panel and blocks transmission of photostimulated light, and a backside phosphor layer. 4. A radiation image conversion panel comprising a transparent support and a phosphor layer comprising stimulable phosphor particles provided on the support, wherein the phosphor layer is a phosphor on the front side. layer,
An excitation light for extracting the stimulating light from the radiation image conversion panel is transmitted therethrough, and the excitation light is transmitted to one surface of the radiation image conversion panel including the intermediate layer and the back surface side phosphor layer, which block transmission of the stimulating light. And irradiating the excitation light with photostimulated light generated from the phosphor layer by photoelectrically reading from both sides of the radiation image conversion panel to obtain an electric signal, and then combining the electric signals obtained from both sides to form an image. A method for reproducing a radiation image recorded on a radiation image conversion panel, the method comprising processing.