JP3133557B2 - Radiation image conversion panel and radiation image conversion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image conversion method utilizing the stimulable properties of a stimulable phosphor and a radiation image conversion panel which can be advantageously used in the method. The present invention particularly relates to a radiation image conversion method for simultaneously detecting stimulated emission from both surface sides, and a radiation image conversion panel that can be advantageously used in the method.

[0002]

2. Description of the Related Art As a method for obtaining a radiographic image as an image, as a method replacing the radiographic method using a combination of a radiographic film having a silver salt emulsion layer and an intensifying screen, for example, a method disclosed in A radiation image conversion method using a stimulable phosphor as described in JP-A-55-12145 or the like has come to be used. This radiation image conversion method uses a radiation image conversion panel (also referred to as a stimulable phosphor sheet) having a stimulable phosphor, and transmits radiation transmitted through a subject or radiation emitted from a subject to the panel. The stimulable phosphor is absorbed in the stimulable phosphor, and thereafter, the stimulable phosphor is excited in a time-series manner by electromagnetic waves (excitation light) such as visible light and infrared light, whereby the stimulable phosphor is accumulated in the stimulable phosphor. The emitted radiation energy is emitted as fluorescent light (stimulated light emission), the fluorescent light is read photoelectrically to obtain an electric signal, and then the electric signal is imaged.

According to the above-mentioned radiation image conversion method, there is an advantage that a radiation image rich in the 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 radiation image conversion method generally has a basic structure consisting of a support and a stimulable phosphor layer provided on one side thereof, and is usually in the form of a rectangular or square sheet. Having. In general, a transparent protective film is provided on the surface of the stimulable phosphor layer opposite to the support (that is, the surface not facing the support), and the phosphor layer is provided with a transparent protective film. Protects against chemical alteration or physical impact.

The stimulable phosphor layer is composed of stimulable phosphor particles and a binder (also referred to as a binder or a binder) which contains and supports the stimulable phosphor particles in a dispersed state. Has a property of emitting light (stimulated emission) when irradiated with electromagnetic waves (excitation light) such as visible light or infrared light after absorbing radiation such as X-rays. Therefore, radiation transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and the radiation of the subject or the subject is displayed on the radiation image conversion panel. A radiation image is formed as an accumulated image (latent image) of radiation energy. This accumulated image can be radiated as stimulated emission by exciting the panel in a time series with the electromagnetic wave, and the stimulated emission is photoelectrically read and converted into an electric signal, and the accumulated image of radiation energy is obtained. It becomes possible to make an image.

The above-described radiation image conversion method generally includes a means for irradiating a radiation image conversion panel with radiation having image information to record a radiation image on the panel (recording means), and a method for exciting a radiation image on a panel on which the radiation image is recorded. A means for irradiating light to cause the panel to emit stimulating light to photoelectrically read a radiation image (reading means)
Means for irradiating the read panel with erasing light to erase the radiation image remaining on the panel (erase means), and a transport for connecting the processing means and transporting the panel toward each processing means. A system in which the recording means and the reading means and the erasing means are separated by using an integrated radiation image recording and reading apparatus in which the system is incorporated in one apparatus, that is, a radiation image recording apparatus (imaging apparatus) and an erasing function This is performed using a radiation image reading apparatus having the following. In either case, the panel after erasing can be used for recording radiographic images, so the panels are used repeatedly.In particular, in the former radiographic image recording and reading device, the panels are circulated and reused while repeating transport and movement within the device. Is done. For this reason, the radiation image conversion panel used in such a normal radiation image conversion apparatus includes a thickness and a type of a support and a stimulable phosphor layer for the purpose of facilitating movement and direction change in the apparatus. The flexibility (ease of bending) is imparted by appropriately selecting the thickness, type and amount of the binder, and the like.

In the reading step in the radiation image conversion method, in general, the excitation light is irradiated from one surface side of the radiation image conversion panel, and the stimulable phosphor emitted from the stimulable phosphor particles is irradiated with the excitation light.
A method is used in which the light is extracted by a condensing guide provided on the excitation light irradiation side, photoelectrically converted, and read. However, when it is desired to extract as much stimulable light emitted from the stimulable phosphor particles as possible, or the accumulated image of the radiation energy formed in the stimulable phosphor layer has energy in the depth direction within the layer. If you want to obtain the change in energy intensity distribution as radiation image information when the intensity distribution is changing, use the method of condensing stimulating light from both sides of the radiation image conversion panel (double-sided condensing reading method) May be. FIG. 1 shows a conceptual diagram of a reading apparatus of a radiation image conversion method using such a light condensing system. In FIG. 1, the radiation image conversion panel is indicated by 11, and a pair of nip rollers for moving and transporting the radiation image conversion panel 11 are denoted by 12 a and 12 a.
This is indicated by b. Excitation light 13 such as a laser beam is irradiated from one side, and the stimulating light emitted from the inside of the radiation image conversion panel 11 proceeds to both surface sides thereof, and the stimulating light proceeds to the lower side of the panel 11 among them. 14a is condensed by a condensing guide 15a provided on the lower side, is converted into an electric signal by a photoelectric conversion device (photomultiplier) 16a provided at the base of the condensing guide 15a, and is amplified by an amplifier 17a. The signal is sent to the signal processing device 18. On the other hand, the stimulated emission 14b that has advanced to the upper side of the radiation image conversion panel 11 is directly or reflected by the mirror 19,
The light is condensed by a condensing guide 15b provided above, is converted into an electric signal by a photoelectric conversion device (photomultiplier) 16b provided at the base of the condensing guide 15b, and is amplified by an amplifier 17b. 18 is sent. The signal processing device 18 performs predetermined arithmetic processing such as addition or subtraction on the electric signal sent from the amplifier 17a and the amplifier 17b based on the type of the target radiation image. The signal is sent out as an image signal.

[0008]

In the radiation image conversion method utilizing the double-sided condensing reading method as described above, as shown in FIG. 1, the reading system is suspended in the air between two sets of nip rollers in the reading system. State. At this time, if the radiation image conversion panel is deformed beyond a certain degree, a partially blurred area is finally generated in the finally obtained radiation image, which adversely affects the image quality of the subsequent radiation image. Further, when the radiation image conversion panel is protruded from one set of nip rollers and is sandwiched between the other set of nip rollers, a trouble is likely to occur due to deformation of the radiation image conversion panel.

[0009]

A stimulable phosphor layer comprising stimulable phosphor particles and a binder for dispersing and supporting the particles, and at least one surface (preferably both surfaces) of the layer.
A radiation image conversion panel comprising a transparent resin film layer having a thickness of 30 μm or less, wherein the panel has a curl of 3 mm or less when measured by placing the panel on a horizontal table, and holds the end of the panel horizontally. 5 mm or less (preferably 0.1 to 3 m)
m) A radiation image conversion panel characterized in that: A stimulable phosphor layer comprising stimulable phosphor particles and a binder for dispersing and supporting the particles, and a transparent resin film layer having a thickness of 30 μm or less is provided on at least one surface (preferably, both surfaces) of the layer. A radiation image conversion panel comprising:
When the panel is placed on a horizontal table, the curl is 3
mm or less, and the edge of the panel is 70 m from a horizontal table.
The radiation image conversion panel having a tip deflection of 5 mm or less (preferably 0.1 to 3 mm) when the m
By irradiating the radiation transmitted through the subject or the radiation emitted from the subject, the radiation is absorbed by the stimulable phosphor particles, and then, while the radiation image conversion panel is transported and moved, the radiation image conversion panel is moved to the surface on one side thereof. By irradiating the excitation light, the radiation energy accumulated in the stimulable phosphor is emitted in a time-series manner as stimulating light, and the stimulating light is emitted from both surface sides of the radiation image conversion panel. A radiation image conversion method comprising photoelectrically reading an electric signal to obtain an electric signal, and then combining and processing the electric signals obtained on both surfaces to form an image.

The “curl” defined in the present invention is:
As shown in FIG. 2, the radiation image conversion panel is placed on a horizontal table with its bulging side (convex side) facing down, and the height of the lower surface of the highest part (h, unit: mm)
Means the value measured.

The “deflection” defined in the present invention is:
As shown in FIG. 3, the radiation image conversion panel is placed on a horizontal table, and one end of the panel is projected from the table by 70 mm. Means the vertical distance (j, unit: mm) to the lower surface.

In the radiation image conversion panel of the present invention,
By adjusting the thickness of the phosphor layer, the type of binder, the ratio of phosphor and binder, etc., the amount of deflection on the panel surface side including the phosphor layer is adjusted to a certain range and curl is suppressed. are doing.

The radiation image storage panel of the present invention can be manufactured, for example, by the following method.

As described above, the stimulable phosphor emits stimulable light when irradiated with radiation and then with excitation light, but from a practical point of view, has a wavelength of 400 to 900 nm.
It is desirable that the phosphor exhibit a photostimulated emission in the wavelength range of 300 to 500 nm by the excitation light in the range of m.
Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention,

SrS: Ce, Sm, SrS: Eu, Sm, ThO described in US Pat. No. 3,859,527.
₂ : Er, and La ₂ O ₂ S: Eu, Sm;
No. 5-12142, ZnS: Cu, Pb, Ba
O.xAl ₂ O ₃ : Eu (where 0.8 ≦ x ≦ 1
0) and M ^II O.xSiO ₂ : A (where M ^II is M
g, Ca, Sr, Zn, Cd or Ba, and A is C
e, Tb, Eu, Tm, Pb, Tl, Bi, or Mn
And x is 0.5 ≦ x ≦ 2.5),

(Ba _{1 -xy} , Mg _x , Ca _y ) FX: aEu ²⁺ described in JP _-A- 55-12143 (where X is at least one of Cl and Br, x and y is 0 <x + y ≦ 0.6 and xy ≠ 0, and a is 10 ⁻⁶ ≦ a ≦ 5 × 10 ⁻² ),

Ln described in JP-A-55-12144
OX: xA (where Ln is La, Y, Gd, and L
at least one of u, 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),

(Ba _1-x , M ²⁺ _x ) FX: yA described in JP-A-55-12145 (where M ²⁺ is M
g, at least one of Ca, Sr, Zn and Cd, X is at least one of Cl, Br and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho,
At least one of Nd, Yb, and Er, and x is 0 ≦ x ≦ 0.6, and y is 0 ≦ y ≦ 0.2),

M ^II FX · xA: yLn described in JP-A-55-160078 [where M ^II is Ba, Ca,
At least one of 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 , GeO ₂ , SnO
₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and at least one of ThO ₂ , Ln is Eu, Tb, Ce, Tm, D
y, Pr, Ho, Nd, Yb, Er, Sm, and Gd
X is at least one of Cl, Br, and I, and x and y are each 5
× 10 ⁻⁵ ≦ x ≦ 0.5 and 0 <y ≦ 0.2].

(Ba _{1 -x} , M ^II _x ) F ₂ .aBaX ₂ : yEu, zA described in JP-A-56-116777
[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 zirconium and scandium] , A, x, y, and z
Are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶
≦ y ≦ 2 × 10 ⁻¹ , and 0 <z ≦ 10 ⁻² ].

(B) described in JP-A-57-23673.
^{_{a 1-x, M II x}} ) F 2 · aBaX 2: yEu, zB [ However, M ^II is beryllium, magnesium, calcium,
At least one of strontium, zinc and cadmium, X is at least one of chlorine, bromine and iodine, 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 ≦ 2 × 10 ^-1 ],

(B) described in JP-A-57-23675
^{_{a 1-x, M II x}} ) F 2 · aBaX 2: yEu, zA [ However, M ^II is beryllium, magnesium, calcium,
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 each at least one of strontium, zinc and cadmium. 5 ≦ a
≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦ 2 × 10 ⁻¹ , and 0 <z ≦ 5 × 10 ⁻¹ ].

M described in JP-A-58-69281
^III OX: xCe [where M ^III is Pr, Nd, P
m, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
b, and at least one trivalent metal selected from the group consisting of Bi, X is one or both of Cl and Br, and x is 0 <x <0.1]. A phosphor represented by the formula:

B described in JP-A-58-206678
a _1-x M _{x / 2} L _{x / 2} FX: yEu ²⁺ [where M is L
L represents at least one alkali metal selected from the group consisting of i, Na, K, Rb and Cs;
Y, La, Ce, Pr, Nd, Pm, Sm, Gd, T
b, Dy, Ho, Er, Tm, Yb, Lu, Al, G
X represents at least one trivalent metal selected from the group consisting of a, In, and Tl; X represents at least one halogen selected from the group consisting of Cl, Br, and I; and x represents 10 ^-2. ≦ x ≦ 0.5, y is 0 <y
≦ 0.1], a phosphor represented by a composition formula:

B described in JP-A-59-27980
aFX · xA: yEu ²⁺ [where X is Cl, Br,
A is at least one halogen selected from the group consisting of and I; A is a calcined product of a tetrafluoroborate compound; and x is 10 ⁻⁶ ≦ x ≦ 0.1, and y is 0 <y
≦ 0.1], a phosphor represented by a composition formula:

B described in JP-A-59-47289
aFX · xA: yEu ²⁺ [where X is Cl, Br,
And A is selected from the group consisting of hexafluorosilicic acid, hexafluorotitanic acid and a salt of a monovalent or divalent metal of hexafluorozirconic acid. X is a calcined product of at least one compound; and x is 10 ⁻⁶ ≦ x ≦ 0.1, and y is 0 <y ≦
0.1], a phosphor represented by a composition formula:

B described in JP-A-59-56479
aFX.xNaX ': aEu ²⁺ [where X and X'
Is at least one of Cl, Br, and I, and x and a are respectively 0 <x ≦ 2 and 0 <a ≦ 0.2].

M described in JP-A-59-56480
^II FX.xNaX ': yEu ²⁺ : zA [where M ^II is
X and X 'are at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
A is at least one halogen selected from the group consisting of Cl, Br and I; A is V, Cr, M
x is at least one transition metal selected from n, Fe, Co, and Ni; and x is 0 <x ≦ 2, and y is 0
<Y ≦ 0.2 and z is 0 <z ≦ 10 ⁻² ], a phosphor represented by a composition formula:

M ^II described in JP-A-59-75200
FX ・ aM ^I X ′ ・ bM ′ ^II X ″ ₂・ cM ^III X ″ ′ ₃・
xA: yEu ²⁺ [where M ^II is Ba, Sr, and C
is at least one alkaline earth metal selected from the group consisting of a; M ^I is Li, Na, K, Rb, and C
M ′ ^II is at least one divalent metal selected from the group consisting of Be and Mg; M ^III is Al,
X is at least one trivalent metal selected from the group consisting of Ga, In, and Tl; A is a metal oxide;
Is at least one halogen selected from the group consisting of Cl, Br, and I; X ′, X ″ and X ″ ″ are
Is 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 ≦ 10 ⁻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], a phosphor represented by a composition formula:

M ^II described in JP-A-60-84381
X ₂ · aM ^II X ′ ₂ : xEu ²⁺ [where M ^II is Ba,
At least one alkaline earth metal selected from the group consisting of Sr and Ca; X and X 'are Cl, Br
At least one halogen selected from the group consisting of and I, and X ≠ X ′; and a is 0.1 ≦ a ≦
10.0, x is 0 <x ≦ 0.2], a stimulable phosphor represented by a composition formula:

M described in JP-A-60-101173
^{II FX · aM I X ':} xEu 2+ [ However, M ^II is Ba,
M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; M is at least one alkaline earth metal selected from the group consisting of Sr and Ca; X is from the group consisting of Cl, Br and I X 'is at least one halogen selected; X' is F, Cl, Br
And at least one halogen selected from the group consisting of I and I; and a and x are each 0 ≦ a ≦
4.0 and 0 <x ≦ 0.2], a stimulable phosphor represented by a composition formula:

M described in JP-A-62-25189
^I X: xBi [However, M ^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; and x is 0 <x ≦ 0.2
A stimulable phosphor represented by the composition formula:

L described in JP-A-2-229882
nOX: xCe (where Ln is at least one of La, Y, Gd and Lu, X is Cl, Br and I
At least one of x is 0 <x ≦ 0.2,
The ratio of Ln to X is 0.500 <X / Ln ≦
And cerium-activated rare earth oxyhalide phosphors having a maximum wavelength λ of 0.998 and a stimulable excitation spectrum having a maximum wavelength λ of 550 nm <λ <700 nm.

The M ^II X ₂ · aM ^II X ′ ₂ : xEu ²⁺ stimulable phosphor described in JP-A-60-84381 described above contains the following additives M ^II X ₂・ aM
^II X ′ ₂ may be contained in the following ratio per 1 mol.
BM ^I X described in JP 60-166379 discloses "
(Where M ^I is at least one alkali metal selected from the group consisting of Rb and Cs, and X ″ is F, C
at least one halogen selected from the group consisting of l, Br and I, and b is 0 <b ≦ 10.0); bK described in JP-A-60-221483
_{X "· 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 selected from the group consisting of F, Cl, Br and I At least one halogen, 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-60-228592 (provided that y is 2 × 10 ⁻⁴ ≦ y ≦ 2 × 10 ⁻¹ ); and yB described in JP-A-60-228593. bA
(Where A is at least one oxide selected from the group consisting of SiO ₂ and P ₂ O ₅ , and b is 1
0 at ^-4 ≦ b ≦ 2 × 10 ^-1 is); JP 61-1208
No. 83, where b is 0 <b ≦ 3
× 10 ^-2 ); bSnX ″ ₂ described in JP-A-61-120885, wherein X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I; Is 0 <b ≦ 10 ⁻³ ); bCsX ″ · cSn described in JP-A-61-235486.
X "' ₂ (where X" and X "' are each 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 );
And bCsX ".yLn3 ⁺ (where X" is F, Cl, B
rn is at least one halogen selected from the group consisting of r and I, and Ln is Sc, Y, Ce, Pr, Nd, S
m, Gd, Tb, Dy, Ho, Er, Tm, Yb, and at least one rare earth element selected from the group consisting of Lu, and b and y are each 0 <b ≦ 1.
0.0 and 10 ⁻⁶ ≦ y ≦ 1.8 × 10 ⁻¹ ).

Further, according to Japanese Patent Application No. Hei 4-276540 specification, the following composition formula (I): BaFX · aNaX ' · dCsX "· eCaX'" 2 · fSrX "" 2 · gCaO · hSrO: bCe 3+ ... (I) (where X is at least one halogen selected from the group consisting of Cl, Br and I; X 'is Br and / or
Or X ", X", X '"and X""are F, Cl, B
at least one halogen selected from the group consisting of r and I; a, d, e, f, g and h are 10 ⁻⁴ ≦
a + d + e + f + g + h ≦ 10 ⁻¹ , and b is a value in the range of 10 ⁻⁵ ≦ b ≦ 10 ⁻² . Cerium-activated barium fluoride halide phosphor represented by the following formula (II): BaFX.aNaX ': bCe ³⁺ (II) (where X is a group consisting of Cl, Br and I) X 'is Br and / or I; and a and b are each 0 <
A cerium-activated barium fluorohalide-based phosphor represented by a ≦ 10 ⁻¹ and 10 ⁻⁵ ≦ b ≦ 10 ⁻² ) can also be advantageously used.

Among the above stimulable phosphors, rare earth element activated rare earth oxyhalides such as divalent europium activated or cerium activated alkaline earth metal halide phosphors and cerium activated rare earth oxyhalide phosphors. The system phosphor is particularly preferable because it shows a high-luminance photostimulated luminescence. However, the stimulable phosphor used in the present invention is not limited to the above-described phosphors, and any phosphor that emits stimulable light when irradiated with radiation and then with excitation light is used. It may be.

Examples of the binder of the stimulable phosphor layer include:
Natural polymers such as proteins such as gelatin, polysaccharides such as dextran; and polyvinyl butyral, polyvinyl acetate, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, vinyl chloride / vinyl acetate copolymer, cellulose acetate butyrate, polyvinyl alcohol; Examples thereof include polymers represented by synthetic high molecular substances such as linear polyester, polystyrene, and epoxy resin. Since the flexibility of such a binder varies depending on the molecular structure, the molecular weight, and the like, it is preferable to select a relatively hard binder. Particularly preferred are polystyrene, epoxy resin, or a mixture of these resins with another polymer, which can easily improve the rigidity of the stimulable phosphor layer. These binders may be cross-linked by a cross-linking agent.

The stimulable phosphor layer can be formed, for example, by the following method. First, the stimulable phosphor and the binder are added to an appropriate solvent, and the mixture is sufficiently mixed to prepare a coating solution in which the phosphor particles are uniformly dispersed in the binder solution. Examples of the solvent for preparing the coating liquid include lower alcohols such as methanol, ethanol, n-propanol and n-butanol; hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. Esters of lower fatty acids such as methyl acetate, ethyl acetate and butyl acetate with lower alcohols; ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; and mixtures thereof.

The mixing ratio between the binder and the stimulable phosphor in the coating solution varies depending on the desired characteristics of the radiation image conversion panel, the type of the phosphor, and the like. Generally, the mixing ratio between the binder and the phosphor is as follows. 1: 1 to 1: 100 (weight ratio)
Is selected from the range. And it is preferable to select from the range of 1: 8 to 1:40 (weight ratio), and in the present invention, it is particularly preferable to select from the range of 1: 8 to 1:30 (weight ratio).

The coating solution contains a dispersant for improving the dispersibility of the phosphor particles in the coating solution, and the dispersing agent between the binder and the phosphor in the formed phosphor layer (phosphor sheet). Various additives such as a plasticizer for improving the bonding strength of the rubber may be mixed.

The coating solution containing the phosphor particles and the binder prepared as described above is uniformly applied to the surface of a temporary support having a flat surface such as a plastic sheet, a glass plate, or a metal plate. A coating film of the coating solution is formed. This coating operation can be performed by using ordinary coating means, for example, a doctor blade, a roll coater, a knife coater, or the like. Next, the formed coating film is dried by gradually heating to complete the formation of the phosphor layer. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of the phosphor, the mixing ratio of the binder and the phosphor, and is usually 20 μm to 1 mm.
And However, this layer thickness is preferably 50 to 500 μm, and in the present invention, in particular, 100 to 400 μm.
m is preferable. Next, the phosphor layer is peeled off from the temporary support. When a transparent plastic film is used as the temporary support, this can be used as a radiation image conversion panel as it is.

In the present invention, the deflection amount of the radiation image conversion panel may be determined, for example, by mixing one or more of three of the mixing ratio of the phosphor and the binder, the thickness of the phosphor layer, and the type of the binder. Can be adjusted by suitably adjusting the temperature.

A thin transparent plastic film layer having a thickness of 30 μm or less is provided on at least one surface of the phosphor layer (sheet) (usually, the lower surface during transportation), preferably on both surfaces, which has been peeled off from the temporary support. To form The transparent plastic film layer includes, for example, cellulose derivatives such as cellulose acetate and nitrocellulose, or polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, fluoroolefin.
It can be formed by applying a solution prepared by dissolving a transparent polymer material such as a synthetic polymer material such as a vinyl ether copolymer in a suitable solvent to the surface of the phosphor. Or polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate,
A transparent thin film separately formed from polyethylene, vinylidene chloride, polyamide, or the like can also be formed by a method such as bonding to the surface of a phosphor sheet using an appropriate adhesive. The side on which the thin transparent plastic film is not provided may be provided with a transparent support for an ordinary radiation image conversion panel.

In this way, when the panel is placed on a horizontal table, the curl is 3 mm or less, and when the end of the panel is projected 70 mm from the horizontal table, the deflection at the tip is 5 mm. The following radiation image conversion panel of the present invention can be obtained.

Incidentally, Japanese Patent Application Laid-Open No. 55-163500,
As described in JP-A-57-96300, etc., the radiation image conversion panel of the present invention may be colored with a coloring agent, and this coloring can improve the sharpness of an obtained image. it can.

[0046]

In the radiation image conversion panel of the present invention, the amount of deflection of the entire panel including the phosphor layer is controlled by adjusting the thickness of the phosphor layer, the kind of the binder, the ratio of the phosphor to the binder, and the like. It is adjusted to a certain range and curl is suppressed. Therefore, even when the radiation image conversion panel of the present invention is used in a radiation image conversion method using a two-sided condensing system, troubles such as deformation in a reading system and poor engagement with a nip roller, which are particularly problematic, are likely to occur. It hardly occurs, so that a radiographic image can be obtained clearly.

[0047]

【Example】

Example 1 200 g of stimulable divalent europium-activated barium fluorobromide phosphor (BaFBr: Eu ²⁺ ) particles and 10 g of polystyrene resin (DIAREX HF-55, manufactured by Mitsubishi Kasei Polytech Co., Ltd.) were added to methyl ethyl ketone. And the mixing ratio of the binder to the phosphor particles is 1:20.
(Weight ratio) was prepared. This coating solution is placed horizontally on a glass plate and uniformly applied on a polyethylene terephthalate sheet (temporary support having a surface treated with a release agent, thickness: 250 μm) fixed and adhered using a doctor blade. did. After the application, the support on which the coating film is formed is put into a drier, and the temperature inside the drier is set at 2.
The coating was dried by gradually increasing the temperature from 5 ° C to 100 ° C. Thus, a thickness of 250 μm and a length of 20.1 c
m, 25.2 cm wide stimulable phosphor sheet (phosphor layer)
Was formed. The polyethylene terephthalate is peeled off from the stimulable phosphor sheet, and then a transparent polyethylene terephthalate film (thickness: 10 μm) is bonded to both sides of the stimulable phosphor sheet using a polyester-based adhesive. A conversion panel was obtained.

Example 2 On one surface of the stimulable phosphor sheet (peeled from the temporary support) obtained in Example 1,
Fluororesin (fluoroolefin-vinyl ether copolymer: Lumiflon LF-100, manufactured by Asahi Glass Co., Ltd.) 70
g and a crosslinking agent (isocyanate: Desmodur Z437)
And 25 g of Sumitomo Bayer Urethane Co., Ltd.) in a toluene-isopropyl alcohol mixed solvent (1: 1) so as to have a solid content of 10% by weight. After drying, a transparent resin film having a thickness of 5 μm was formed. Next, a transparent resin film having a thickness of 5 μm was similarly formed on the other surface to obtain a radiation image conversion panel according to the present invention.

Example 3 A stimulable divalent europium-activated barium fluoroiodobromide phosphor (BaFBr _0.85 I _0.15 :
Eu ²⁺ ) particles and epoxy resin (Epicoat 1)
009, 10 g of Yuka Shell Epoxy Co., Ltd.) and methyl ethyl ketone were added to prepare a dispersion having a mixing ratio of binder and phosphor particles of 1:20 (weight ratio). Then, the same stimulable phosphor sheet as in Example 1 was formed using this coating solution. Next, the same operation as in Example 1 was performed on both surfaces of the obtained stimulable phosphor sheet to form a transparent resin film having a thickness of 5 μm, thereby obtaining a radiation image conversion panel according to the present invention.

[Example 4] On both surfaces of the stimulable phosphor sheet (peeled from the temporary support) obtained in Example 1,
The operation according to Example 2 was performed to form a transparent resin film having a thickness of 5 μm, and a radiation image conversion panel according to the present invention was obtained.

Comparative Example 1 200 g of stimulable divalent europium-activated barium fluorobromide phosphor (BaFBr: Eu ²⁺ ) particles, polyalkyl acrylate resin (solid content: 8 g), and nitrification degree Methyl ethyl ketone was added to 5% nitrocellulose (solid content: 2 g) to prepare a dispersion of a binder and phosphor particles at a mixing ratio of 1:20. Then, the same stimulable phosphor sheet as in Example 1 was formed using this coating solution. Next, the same operation as in Example 1 was performed on both surfaces of the obtained stimulable phosphor sheet to form a 5 μm-thick transparent resin film, and a comparative radiation image conversion panel was obtained.

[Comparative Example 2] On both surfaces of the stimulable phosphor sheet (peeled from the temporary support) obtained in Comparative Example 1,
The same operation as in Example 2 was performed to form a transparent resin film having a thickness of 5 μm, thereby obtaining a comparative radiation image conversion panel.

Comparative Example 3 200 g of stimulable divalent europium-activated barium fluorobromide phosphor (BaFBr: Eu ²⁺ ) particles and a polyurethane resin (Desmolac TPKL-)
5-2625, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 10 g
Was added to the mixture to prepare a dispersion having a mixing ratio of the binder to the phosphor particles of 1:20 (weight ratio).
Then, the same stimulable phosphor sheet as in Example 1 was formed using this coating solution. Next, the same operation as in Example 1 was performed on both surfaces of the obtained stimulable phosphor sheet to a thickness of 5 μm.
Was formed to obtain a comparative radiation image storage panel.

Comparative Example 4 On both surfaces of the stimulable phosphor sheet (peeled from the temporary support) obtained in Comparative Example 3,
The same operation as in Example 2 was performed to form a transparent resin film having a thickness of 5 μm, thereby obtaining a comparative radiation image conversion panel.

[Comparative Example 5] In Example 1, the coating solution containing stimulable phosphor particles was uniformly applied using a doctor blade onto a polyethylene terephthalate sheet simply placed horizontally on a glass plate. . Then, after coating, the support on which the coating film was formed was placed in a drier, and the temperature inside the drier was gradually increased from 25 ° C. to 100 ° C. to dry the coating film. A similar stimulable phosphor sheet was formed. Next, the same operation as in Example 1 was performed on both surfaces of the obtained stimulable phosphor sheet to a thickness of 5 μm.
Was formed to obtain a comparative radiation image storage panel.

[Comparative Example 6] In Example 3, the coating solution containing stimulable phosphor particles was uniformly applied on a polyethylene terephthalate sheet simply placed horizontally on a glass plate using a doctor blade. . Then, after coating, the support on which the coating film was formed was placed in a drier, and the temperature inside the drier was gradually increased from 25 ° C. to 100 ° C. to dry the coating film. A similar stimulable phosphor sheet was formed. Next, the same operation as in Example 1 was performed on both surfaces of the obtained stimulable phosphor sheet to a thickness of 5 μm.
Was formed to obtain a comparative radiation image storage panel.

[Evaluation of Radiation Image Conversion Panel]
Table 1 shows the deflection amount (mm) of each radiation image conversion panel of Comparative Example 4 and Comparative Examples 1 to 6. The amount of flexure was measured by placing the panel (100 mm x 250 mm) on a horizontal table, leaving the panel in the long-axis direction from the side end of the table by 70 mm, and allowing it to stand. It was determined by measuring the vertical distance from the mounting surface (horizontal plane). The curl of the radiation image conversion panel was measured by the above method.

Table 1 量 Deflection (mm) Curl (mm) ) ──────────────────────────────────── Example 1 1.0 +0.5 Example 22 0.0 +1.0 Example 3 0.5 -0.5 Example 4 1.0 -1.0 ─────────────────────────比較 Comparative Example 1 6.0 +2.0 Comparative Example 2 12.0 -0.5 Comparative Example 3 9.0 -1.0 Comparative Example 4 20.0 +1.5 Comparative Example 5 1.0 + 4.0 Comparative Example 60.5 + 4.5 ───

Next, the image forming performance of each radiation image conversion panel was evaluated by an image output test. Using the double-sided condensing type reader shown in FIG. 1, an image reading output test was performed under the following conditions. Tube voltage 80k for radiation image conversion panel
After irradiating X-rays of Vp, the surface of the panel between the nip rolls is irradiated with He-Ne laser light (excitation light) while the radiation image conversion panel is transported and moved between the nip rolls as shown in FIG. The photostimulated light emitted from the stimulable phosphor layer was condensed from both sides and converted into an electric signal, and the upper and lower signals were summed to obtain an image signal. After the image signals were combined and subjected to arithmetic processing, an image was exposed and recorded on a silver halide photographic film using a film scanner. When the obtained photographic image was observed, the following results were obtained.

Examples 1-4: Any of the radiation image conversion panels could be read without any trouble, and the obtained radiation images were clear and no partial "unevenness" was observed. Comparative Example 1: When the radiation image conversion panel was moved in the reading apparatus, a trouble occurred in which the rear end touched the light-collecting guide, and "unevenness" was observed near the rear end of the obtained radiation image. . Comparative Examples 2 to 4: When the radiation image conversion panel was moved by the reading device, a trouble occurred in which the front end portion touched the light collecting guide and then the nip roller. For this reason, a normal image could not be obtained. Comparative Example 5: When moving the radiation image conversion panel in the reading, a trouble occurred in which the front end portion touched the upper light collection guide, and "unevenness" was observed near the front end portion of the obtained radiation image. . Comparative Example 6: When moving the radiation image conversion panel in reading, a trouble occurred in which the front end portion touched the lower light-collecting guide, and "unevenness" was observed near the front end portion of the obtained radiation image. Was.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a double-sided condensing type reading apparatus used in a radiation image conversion method using the stimulable phosphor of a radiation image conversion panel.

FIG. 2 is a diagram showing a method of measuring “sag (amount)” of a radiation image conversion panel defined in the present invention.

FIG. 3 is a diagram showing a method for measuring “curl” of the radiation image conversion panel defined in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Radiation image conversion panel 12a, 12b Nip roller 13 Excitation light 14a, 14b Luminescence 15a, 15b Condensing guide 16a, 16b Photoelectric conversion device 17a, 17b Amplifier 18a, 18b Signal processing device 19 Mirror

Claims (5)

(57) [Claims] 1. A stimulable phosphor layer comprising stimulable phosphor particles and a binder for dispersing and supporting the particles, and a transparent resin film layer having a thickness of 30 μm or less is provided on at least one surface of the layer. A radiation image conversion panel having a curl of 3 m when measured by placing the panel on a horizontal table.
m or less, and the edge of the panel is 70 mm from a horizontal base.
A deflection of the tip at the time of sticking out is 5 mm or less. 2. A thickness of 30 on both surfaces of the stimulable phosphor layer.
The radiation image storage panel according to claim 1, further comprising a transparent resin film layer having a thickness of not more than μm. 3. A stimulable phosphor layer comprising stimulable phosphor particles and a binder for dispersing and supporting the particles, and a transparent resin film layer having a thickness of 30 μm or less is provided on at least one surface of the layer. A radiation image conversion panel having a curl of 3 m when measured by placing the panel on a horizontal table.
m or less, and the edge of the panel is 70 mm from a horizontal base.
A radiation image conversion panel having a tip deflection of 5 mm or less when sticking out is irradiated with radiation transmitted through the subject or emitted from the subject, and the radiation is absorbed by the stimulable phosphor particles. Then, by irradiating the surface of one side of the radiation image conversion panel with excitation light while transporting and moving the radiation image conversion panel, the radiation energy accumulated in the stimulable phosphor is converted into stimulable emission light. The stimulated emission light is photoelectrically read from both front sides of the radiation image conversion panel to obtain electric signals, and then the electric signals obtained on both front sides are combined and arithmetically processed. A radiation image conversion method comprising: 4. A radiation image conversion panel according to claim 3, wherein the radiation image conversion panel is a radiation image conversion panel having a transparent resin film layer having a thickness of 30 μm or less on both surfaces of a stimulable phosphor layer. Conversion method. 5. The radiation image conversion method according to claim 3, wherein the radiation image conversion panel is conveyed and moved between two pairs of nip rollers while irradiating the surface of the radiation image conversion panel located between the nip rollers with excitation light.