JP3130633B2 - Manufacturing method of radiation image conversion panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic image comprising a step of vapor-depositing a stimulable phosphor on a surface of a substrate using a vapor stream to form at least one stimulable phosphor layer. The present invention relates to a method for manufacturing a conversion panel.

[0002]

2. Description of the Related Art In the medical field, for example, radiation images such as X-ray images are often used for diagnosing diseases. Conventionally, as a method of forming a radiation image, X-rays transmitted through a subject are irradiated on a phosphor layer (fluorescent screen) to generate visible light, and this visible light is used in the same manner as when a normal photograph is taken. A so-called radiographic method of irradiating and developing a film using a silver salt has been generally used.

However, in recent years, as a method of directly taking out an image from a phosphor layer without using a film coated with a silver salt, radiation that has passed through a subject is absorbed by the phosphor, and then the phosphor is irradiated with light or heat, for example. A method has been proposed in which, by excitation with energy, radiation energy absorbed and accumulated in the phosphor is emitted as fluorescence, and the fluorescence is detected and imaged.

For example, US Pat. No. 3,859,527 and JP-A-55-12144 show a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulating excitation light. ing. In this method, a radiation image conversion panel having a stimulable phosphor layer formed on a substrate is used. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance of each part, and then the radiation energy accumulated in each part is stimulated by scanning the stimulable phosphor layer with stimulating excitation light. The light is emitted as light emission, and an optical signal based on the intensity of the light is photoelectrically converted, for example, and is imaged by an image reproducing apparatus. This final image may be played as a hard copy or on a display such as a CRT.

A radiation image conversion panel having a stimulable phosphor layer used in such a radiation image conversion method includes:
As in the case of the above-described radiographic method using a fluorescent screen, it is necessary to have a high radiation absorption rate and a high light conversion rate (hereinafter, referred to as “radiation sensitivity”), and high image sharpness is required. Is required.

By the way, the sharpness of an image in a radiation image conversion panel using a stimulable phosphor is not determined by the spread of the stimulable luminescence of the stimulable phosphor, but by the panel of the stimulable excitation light. It is determined depending on the spread within. More specifically, since the radiation image information stored in the radiation image conversion panel is time-sequentially extracted, the photostimulated light emitted by the photostimulated excitation light irradiated at a certain time (t _i ) is preferably all collected. At that time, a pixel (x _i ,
y _i ), the stimulating excitation light spreads in the panel due to scattering or the like, and the illuminated pixel (x
_i, when thus excited even a stimulable phosphor which is present on the outside of y _i), the irradiation pixel (x _i, the output from the region wider than the pixel as output from y _i) are recorded I will. Therefore, the stimulating light emitted by the stimulating excitation light irradiated at a certain time (t _i ) is changed to the pixel (x _i , y) on the panel to which the stimulating light was truly irradiated at the time (t _i ). The light emission from _i ) alone has no effect on the sharpness of the obtained image, regardless of the extent of the light emission. In such a situation, as a technique for improving the sharpness of a radiographic image, for example, a radiographic image conversion panel in which a stimulable phosphor layer is formed of fine columnar crystals and a method for manufacturing the same have been proposed (Japanese Patent Application Laid-Open No. H10-163,878). 61-142497-142
Nos. 500 and 62-105098). According to this technique, the stimulating excitation light reaches the bottom of the columnar crystal without dissipating outside the columnar crystal while repeating reflection within the columnar crystal due to the light guiding effect of the fine columnar crystal,
The sharpness of an image due to stimulated emission can be further increased. In particular, when a layer is formed by vapor-phase deposition on a surface of a substrate to be vapor-deposited using a vapor flow, conventionally, a stimulable phosphor layer is formed by an oblique vapor deposition method, thereby focusing on the direction of the vapor flow. Means for improving the sharpness of a radiation image have been proposed (see Japanese Patent Application No. 63-129996).
.

[0007]

However, in the above technique, the stimulable phosphor has a plate-like shape connected in one direction, so that the sharpness greatly differs depending on the reading direction of the radiation image. There was a problem. That is,
When the vapor flow is incident obliquely on the substrate surface, a shadow is formed on the substrate surface where it is difficult for the vapor flow to reach. Is improved. However, in the conventional vapor deposition method, since the streamline direction of the vapor flow is fixed with respect to the substrate surface, the "shadow" portion is deviated, and the width of the plate differs greatly depending on the direction instead of the narrow column shape. The resulting crystal has a problem that the sharpness varies depending on the reading direction.

Accordingly, an object of the present invention is to form a stimulable phosphor layer composed of a columnar crystal having a narrow width and high accuracy, thereby improving the sharpness of a radiographic image and the sharpness in a reading direction. It is an object of the present invention to provide a method capable of manufacturing a radiation image conversion panel having a small change.

[0009]

According to the manufacturing method of the present invention, at least one stimulable phosphor layer is formed by vapor-phase depositing a stimulable phosphor on a surface to be deposited of a substrate using a vapor flow. In the method for manufacturing a radiation image conversion panel including a step, while the streamline direction of the vapor flow is relatively rotated around the normal direction of the deposition surface of the substrate, the photostimulable It is characterized in that the phosphor is deposited in a vapor phase.

[0010]

According to the present invention, when the stimulable phosphor is deposited in the vapor phase, the streamline direction of the vapor flow is relatively rotated around the normal direction of the surface of the substrate to be deposited. It becomes fine columnar crystals that are clearly separated from each other without spreading. In other words, when the streamline direction of the vapor flow is obliquely inclined with respect to the deposition surface of the substrate, the crystal tends to grow obliquely under the influence of the streamline direction, and the vapor flow hardly reaches the deposition surface of the substrate. A "shadow" portion is formed, and this portion becomes a crack to form a partitioned crystal that extends with a certain inclination in the streamline direction of the steam flow. Conventionally, this "shadow" portion was fixed, so the crystal spread in a plate shape, making it difficult to obtain a fine columnar crystal.In the present invention, the substrate was adjusted so that the "shadow" portion was not biased. Since the streamline direction of the vapor flow is relatively rotated around the normal direction of the surface to be vapor-deposited, a stimulable phosphor layer composed of fine columnar crystals having a small width can be obtained. Therefore, it is possible to obtain a radiation image conversion panel which is excellent in the sharpness of a radiation image and has a small change in sharpness depending on the reading direction. For convenience, the streamline direction of the vapor flow is defined as a point where the evaporation source is regarded as a point in consideration of the evaporation amount distribution in the vicinity of the evaporation source, and a direction connecting this point and each point on the surface of the substrate on which the evaporation is to be performed. Say. The normal direction of the deposition surface of the substrate is the normal direction when the deposition surface is approximated to a flat surface or a curved surface having a constant curvature.Partial warpage, undulation, or unevenness of the deposition surface is Shall not be taken into account.

[0011]

In the embodiment shown in FIG. 1, a substrate 1 is fixedly arranged in a horizontal position, and an evaporation source 2 made of a stimulable phosphor material can revolve at a position below a deposition surface 1A of the substrate 1. Are located in When the evaporation source 2 is evaporated by an excitation means such as an electron beam to form a steam flow while revolving the evaporation source 2 about the normal direction B at the center of the surface 1A to be evaporated, the streamline direction A of the steam flow becomes The substrate 1 relatively rotates around the normal direction B. Therefore, on the deposition surface 1A of the substrate 1, the "shadow" portion where the vapor flow is difficult to reach is not biased, and a stimulable phosphor layer made of fine columnar crystals having a small width is obtained. As described above, the streamline direction A of the vapor flow is, for convenience, considered as the point of the evaporation source 2 in consideration of the evaporation amount distribution near the evaporation source 2, and this point and the deposition surface 1 A of the substrate 1. Means the direction connecting each point.

In the embodiment shown in FIG. 2, an evaporation source 2 made of a stimulable phosphor material is fixedly arranged, and at a position above the evaporation source 2, the substrate 1 moves in a horizontal plane in a normal direction B at the center thereof. It is arranged so that it can rotate around the center. While rotating the substrate 1 in a horizontal plane about the normal direction B, the evaporation source 2 is excited by an excitation means such as an electron beam.
Is evaporated to form a vapor flow, the streamline direction A of the vapor flow relatively rotates around the normal direction B at the center of the substrate 1. Therefore, a stimulable phosphor layer composed of fine columnar crystals having a small width can be obtained.

In the embodiment shown in FIG. 3, an evaporation source 2 made of a stimulable phosphor material is fixed, and at a position above the evaporation source 2, the substrate 1 is moved in a normal direction B at the center thereof in an inclined plane. It is arranged so that it can rotate around the center.
When the evaporation source 2 is evaporated by an excitation means such as an electron beam to form a vapor flow while the substrate 1 is rotated on an inclined plane with the normal direction B as an axis, the streamline direction A of the vapor flow becomes Will rotate relatively in the direction of the normal B at the center of. Therefore, a stimulable phosphor layer composed of fine columnar crystals having a small width can be obtained.

In the embodiment shown in FIG. 4, an annular evaporation source 2 made of a stimulable phosphor material is fixedly arranged in a horizontal position, and an electron beam generator 3 is provided at the center of the annular evaporation source 2. The substrate 1 is fixedly arranged in a horizontal position at a position above the evaporation source 2. When the irradiation position of the electron beam 3A from the electron beam generator 3 is sequentially or randomly moved along the circumference of the annular evaporation source 2 to evaporate the evaporation source 2 and form a steam flow, The streamline direction A relatively rotates around the normal direction B of the substrate 1. Therefore, a stimulable phosphor layer composed of fine columnar crystals having a small width can be obtained.

In the present invention, when performing vapor phase deposition,
The intersection angle (acute angle) θ (see FIG. 1) between the streamline direction A of the vapor flow and the normal direction of the surface on which the substrate is to be deposited is preferably larger than 0 ° and 80 ° or less, preferably 5 ° or more and 70 ° or less. Is particularly preferred. If θ is too small, it is difficult to form a “shadow” portion, and it is difficult to form a fine columnar crystal having the portion as a crack. On the other hand, if θ is too large, the mechanical strength of the phosphor layer and the adhesion to the substrate are reduced, and the flaws and the peeling of the film are likely to occur.

As shown in FIG. 5, when the streamline direction A of the vapor flow is relatively rotated around the normal direction B of the surface 1A of the substrate 1 to be evaporated, the evaporation source 2 is set at the starting point. The intersection angle φ between the sum vector C of the vapor flow vector at each point on the deposition surface 1A and the normal direction of the deposition surface 1A at each point where the normal intersects the deposition surface 1A is 0 °. It is preferably at least 30 ° and at most 30 °, particularly preferably at least 0 ° and at most 10 °. Each of the partitioned fine columnar crystals grows to some extent in the direction of the sum vector C of the vapor flow vectors at each point on the deposition surface 1A, and the growth direction is close to the normal direction of the deposition surface 1A ( The smaller the intersection angle φ), the smaller the deviation of cracks caused by the steam flow becoming “shadow”. Therefore, the closer the direction of the sum vector C is to the normal direction of the deposition target surface 1A (the smaller the intersection angle φ), the more
This makes it possible to manufacture a radiation image conversion panel having a small difference in sharpness depending on the reading direction of the radiation image.

In the present invention, the stimulable phosphor layer is formed by a vapor deposition method. As the vapor deposition method, an evaporation method is preferably used. In particular, an electron beam evaporation method and a resistance heating evaporation method are used. It is preferably used. When the stimulable phosphor layer is formed by an evaporation method, the stimulable phosphor layer having a multilayer structure may be formed by performing vapor deposition a plurality of times. In the evaporation method, the substrate may be cooled or heated as needed during the evaporation. Further, the stimulable phosphor layer may be subjected to a heat treatment (annealing) after the deposition. In the vapor deposition method, reactive vapor deposition may be performed by introducing a gas such as O ₂ or H ₂ as necessary.

In the step of forming the stimulable phosphor layer by the vapor deposition method, the deposition rate of the stimulable phosphor layer is 0.1 to 50.
μm / min is preferred. If the deposition rate is too low, the productivity will be low, and if the deposition rate is too high, it will be difficult to control the deposition rate. By the way, it is clear that the “shadow” portion, which is difficult to reach by the steam flow caused by making the steam flow obliquely incident on the substrate surface, is more likely to occur as the straightness of the steam flow is higher (there is less wraparound). Therefore, in order to form fine crystals partitioned by cracks, the lower the pressure of the deposition atmosphere (the higher the degree of vacuum), the better. Specifically, the deposition atmosphere pressure is 5 × 10 ⁻⁴ Torr.
r, preferably 5 × 10 ⁻⁵ Torr or less. Further, in the step of forming the stimulable phosphor layer by the vapor deposition method, the temperature of the substrate is preferably at least 100 ° C. lower than the melting point of the evaporating substance from the viewpoint of preventing the sharpness of the image from being reduced due to the enlargement of the crystal. preferable.
The thickness of the stimulable phosphor layer depends on the radiation sensitivity of the intended radiation image conversion panel, the type of the stimulable phosphor, etc., but from the viewpoint of preventing a decrease in radiation sensitivity due to a decrease in radiation absorption, It is preferably from 30 to 1000 μm, particularly preferably from 50 to 500 μm. When the layer thickness of the stimulable phosphor layer is too small, the radiation absorptivity decreases, so that the radiation sensitivity deteriorates. When the layer thickness is too large, the lateral spread of the stimulable excitation light increases. Therefore, the sharpness of the image deteriorates.

FIGS. 6 and 7 schematically show the columnar crystals 5 of the stimulable phosphor layer 4 formed by the manufacturing method of the present invention. Cracks 6 are formed, and each columnar crystal 5 has an independent structure. Therefore, the stimulating excitation light and the stimulating light are emitted from each columnar crystal 5.
With sharp directivity, and the sharpness of the image is improved. Further, since the columnar crystals of the stimulable phosphor layer formed by the manufacturing method of the present invention do not differ greatly in the average sizes of a and b shown in FIG. 7 (X direction) or the vertical direction (Y direction in FIG. 7), the sharpness is almost even.

The scattering of the stimulating excitation light by the columnar crystal 5 and the decrease in the directivity of the stimulating excitation light are prevented, and the MTF is reduced.
In order to improve the (modulation transfer function of an image), the columnar crystal 5 preferably has a vertical width a and a horizontal width b (see FIG. 7) of about 1 to 50 μm, particularly preferably 1 to 30 μm. It should be noted that the columnar crystal shapes shown in FIGS. 6 and 7 are written schematically, and are not limited to these shapes. Further, the columnar crystal shapes have a uniform shape or a uniform size over the entire phosphor layer. It doesn't have to be.

FIG. 8 shows a specific configuration example of the radiation image conversion panel manufactured by the manufacturing method of the present invention, wherein 7 is a protective layer, 8 is a spacer, and 9 is a low refractive index layer. As a material of the substrate 1, glass, ceramics, various polymer materials, metals, and the like are used. Specifically, quartz glass, glass such as chemically strengthened glass, crystallized glass, ceramics such as a sintered plate of alumina or zirconia, or cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film , A plastic film such as a polycarbonate film, a metal sheet such as aluminum, an aluminum-magnesium alloy, iron, stainless steel, copper, and chromium.
The thickness of the substrate varies depending on its material and the like, but is generally preferably 100 μm to 5 mm, and particularly preferably 200 μm to 2 mm from the viewpoint of convenient handling. The surface of these substrates may be smooth or may be rough for the purpose of improving the adhesion to the stimulable phosphor layer. Further, most of the substrate may be made smooth, and only the peripheral portion may be made rough for the purpose of improving adhesion. In this case, it is preferable to stop the roughened peripheral portion at a portion that is not substantially used as an image, in terms of uniform image quality.

The protective layer 7 is provided for physically or chemically protecting the stimulable phosphor layer 4.
This protective layer 7 may be provided so as to face the stimulable phosphor layer 4 via the low refractive index layer 9 as shown in FIG. It may be formed by directly applying on the upper surface. Further, a protective layer separately formed in advance may be bonded onto the stimulable phosphor layer.

When the protective layer 7 is provided with the low refractive index layer 9 interposed therebetween, the constituent material of the protective layer 7 has good translucency,
What can be formed into a sheet is used. In order for the protective layer 7 to efficiently transmit stimulated excitation light and stimulated emission, it is desirable to exhibit a high light transmittance in a wide wavelength range, and the light transmittance is preferably 80% or more. Examples of such a material include plate glass such as quartz, borosilicate glass, and chemically strengthened glass, and organic polymer compounds such as PET, drawn polypropylene, and polyvinyl chloride. Borosilicate glass shows a light transmittance of 80% or more in a wavelength range of 330 nm to 2.6 μm, and quartz glass shows a high light transmittance even at a shorter wavelength. Furthermore, M
Providing an antireflection layer such as gF ₂ is preferable because it has the effect of efficiently transmitting stimulated excitation light and stimulated emission and also has the effect of reducing sharpness deterioration. The thickness of the protective layer is 50 to 5
000 μm is preferred, and 100-3000 μm is more preferred.

When the protective layer 7 is provided directly on the stimulable phosphor layer 4, the constituent materials of the protective layer 7 include cellulose acetate, nitrocellulose, polymethyl methacrylate, and the like.
Polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, nylon and the like can be used. The protective layer 6 is made of SiC, SiO ₂ , SiN, A
It may be formed by laminating inorganic substances such as l ₂ O ₃ . In this case, the thickness of the protective layer 7 is preferably from 0.1 to 100 μm, and more preferably from 1 to 50 μm.

The low refractive index layer 9 is provided as necessary from the viewpoint of further improving the sharpness of a radiation image. Specifically, CaF ₂ (refractive index 1.23 to 1.2)
6), Na ₃ AlF ₆ (refractive index: 1.35), MgF
₂ (refractive index: 1.38), SiO ₂ (refractive index: 1.46), etc .; ethanol (refractive index: 1.36), methanol (refractive index: 1.33), diethyl ether (refractive index: 1.35) A layer made of a liquid such as air; a layer made of a gas such as air, nitrogen, or argon; a layer having a refractive index of substantially 1 such as a vacuum layer; Particularly, a gas layer or a vacuum layer is preferable. In this case, the thickness of the low refractive index layer 9 is usually 0.05 to 3 mm.

The low-refractive-index layer 9 is preferably in close contact with the stimulable phosphor layer 4. Therefore, when the low-refractive-index layer 9 is a liquid layer, a gas layer, or a vacuum layer, it may be left as it is. However, when the low refractive index layer 9 is formed of CaF ₂ , Na ₃ AlF ₆ , MgF ₂
When it is provided on the inner surface of the protective layer 7 using iO ₂ or the like, the stimulable phosphor layer 4 and the low refractive index layer 9 may be brought into close contact with each other by, for example, an adhesive.

When the protective layer 7 is disposed at a distance from the stimulable phosphor layer 4, a spacer surrounding the stimulable phosphor layer 4 is provided between the substrate 1 and the protective layer 7. 8 are provided. The spacer 8 is not particularly limited as long as it can hold the stimulable phosphor layer 4 in a state of being shielded from the external atmosphere, and glass, ceramics, metal, plastic, or the like can be used. Is preferably not less than the thickness of the stimulable phosphor layer.

In the present invention, the term “stimulable phosphor” refers to a stimulus such as optical, thermal, mechanical, chemical, or electrical (stimulated excitation) after the first irradiation of light or high-energy radiation. ) Means a phosphor that shows stimulated emission corresponding to the dose of the first light or high-energy radiation, but from a practical viewpoint, a phosphor that shows stimulated emission by photostimulation (stimulated excitation). Is preferable, and a phosphor that emits stimulating light by stimulating excitation light having a wavelength of 500 nm or more and 1 μm or less is particularly preferable.

The following can be used as the stimulable phosphor constituting the stimulable phosphor layer. (1) BaSO described in JP-A-48-80487
₄ : Phosphor represented by A _x (where A represents at least one of Dy, Tb, and Tm, and x represents a number satisfying 0.001 ≦ x <1 mol%). (2) SrSO described in JP-A-48-80489
₄ : Phosphor represented by A _x (where A represents at least one of Dy, Tb, and Tm, and x represents a number satisfying 0.001 ≦ x <1 mol%). (3) Na ₂ S described in JP-A-51-29889
A phosphor in which at least one of Mn, Dy, and Tb is added to O ₄ , CaSO ₄ , BaSO _4, or the like. (4) BeO, described in JP-A-52-30487,
Phosphors such as LiF, MgSO ₄ and CaF ₂ . (5) Li ₂ B described in JP-A-53-39277
₄ O ₇ : phosphor such as Cu and Ag.

(6) Li ₂ O. (B ₂ O ₂ ) _x : Cu (where x is 2) described in JP-A-54-47883.
<X ≦ 3. ), Li ₂ O · (B
₂ O ₂ ) _x : a phosphor such as Cu or Ag (where x represents a number satisfying 2 <x ≦ 3). (7) SrS: Ce, Sm, SrS: Eu, Sm, La ₂ O ₂ described in US Pat. No. 3,859,527.
S: Eu, Sm, (Zn, Cd) S: Phosphor represented by Mn, X (where X represents halogen). (8) ZnS described in JP-A-55-12142:
Cu, Pb phosphor. (9) The general formula described in JP-B-55-12142 is Ba.
O.xAl ₂ O ₃ : Eu (where x is 0.8 ≦ x ≦ 10
Represents a number that satisfies Barium aluminate phosphor represented by). (10) The general formula described in JP-A-55-12142 is represented by M
_I O · xSiO _2: A (however, M _I is, Mg, Ca,
Represents Sr, Zn, Cd, Ba, and A is Ce, Tb, E
u represents at least one of Tm, Pb, Tl, Bi, and Mn, and x represents a number satisfying 0.5 ≦ x <2.5. )
An alkaline earth metal silicate phosphor represented by the formula:

(11) The general formula described in JP-A-55-12142 is represented by (Ba _1-xy Mg _x C a _y ) FX: eEu ²⁺
(Where X represents at least one of Br and Cl;
x, y, and e are 0 <x + y ≦ 0.6 and xy ≠, respectively.
It represents a number that satisfies 0, 10 ⁻⁶ ≦ e ≦ 5 × 10 ⁻² . The phosphor represented by). (12) The general formula described in JP-A-55-12142 is LnOX: xA (where Ln is La, Y, Gd, L
u represents at least one kind, X represents at least one kind of Cl and Br, A represents at least one kind of Ce and Tb, and x represents a number satisfying 0 <x <0.1. The phosphor represented by). (13) When the general formula described in JP-A-55-12145 is (Ba _1-x (M _I ) _x ) FX: yA (where M _I
Represents at least one of Mg, Ca, Sr, Zn, and Cd; X represents at least one of Cl, Br, and I;
A is Eu, Tb, Ce, Tm, Dy, Pr, Ho, N
represents at least one of d, Yb and Er, and x and y are 0
It represents a number that satisfies ≦ x ≦ 0.6 and 0 ≦ y ≦ 0.2. The phosphor represented by). (14) The general formula described in JP-A-55-84389 is BaFX: xCe, yA (where X is Cl, B
r, at least one of I, A is In, Tl, G
represents at least one of d, Sm, and Zr, and x and y are 0
<X ≦ 2 × 10 ⁻¹ and 0 <y ≦ 5 × 10 ⁻² . The phosphor represented by). (15) The general formula described in Japanese Patent Application Laid-Open No. 55-160078 is M _I FX · xA: yLn (where M _I is M
g, at least one of Ca, Ba, Sr, Zn, and Cd, where A is BeO, MgO, CaO, SrO, Ba
O, ZnO, Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In
₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , GeO ₂ , S
represents at least one of nO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and ThO ₂ , wherein Ln is Eu, Tb, Ce, Tm, D
y represents at least one kind of Pr, Ho, Nd, Yb, Er, Sm, and Gd, X represents at least one kind of Cl, Br, and I, and x and y represent 5 × 10 ⁻⁵ ≦ x ≦ 0.5, 0 <
represents a number satisfying y ≦ 0.2. ) A rare earth element-activated divalent metal fluorohalide phosphor represented by the formula:

(16) The general formulas described in JP-A-55-160078 are ZnS: A, (Zn, Cd) S: A, Cd
S: A, ZnS: A, X, CdS: A, X (where A
Represents any of Cu, Ag, Au, and Mn, and X represents
Represents halogen. The phosphor represented by). (17) General formula [I] xM ₃ (PO ₄ ) ₂ .NX ₂ : yA described in JP-A-59-38278: General formula [II] M ₃ (PO ₄ ) ₂ .yA (wherein M , N are Mg, Ca, Sr, and B, respectively.
a represents at least one of Zn, Cd, and X represents F, C
1, at least one of Br, I, and A represents Eu, T
b, Ce, Tm, Dy, Pr, Ho, Nd, Yb, E
represents at least one of r, Sb, Tl, Mn, and Sn;
x and y represent numbers that satisfy 0 <x ≦ 6 and 0 ≦ y ≦ 1. The phosphor represented by). (18) General formula [III] described in JP-A-59-155487: nReX ₃ .MAX ' ₂ : xEu General formula [IV] nReX ₃ .MAX' ₂ : xEu,
ySm (where Re is at least one of La, Gd, Y, and Lu)
A represents a species, A represents at least one alkaline earth metal of Ba, Sr, Ca, and X, X ′ represent F, Cl, Br
Wherein x and y are 1 × 10 ⁻⁴ <x <
3 × 10 ⁻¹ , 1 × 10 ⁻⁴ <y <1 × 10 ⁻¹ , and n / m represents a number satisfying 1 × 10 ⁻³ <n / m <7 × 10 ⁻¹ . The phosphor represented by). (19) General formula aBaX ₂ · (1-a) BaY ₂ : bEu ²⁺ described in JP-A-2-58593 (wherein X and Y are at least one of F, Cl, Br and I, respectively) Represents a seed, X ≠ Y, and a and b are 0 <a
<1, 10 ⁻⁵ <b <10 ⁻¹ . The phosphor represented by). (20) JP formula described in JP _{61-72087 M I X · aM II X} '2 · bM III X''3: cA ( However, M _I is, Li, Na, K, Rb , Cs M _II represents Be, M
g, at least one divalent metal of Ca, Sr, Ba, Zn, Cd, Cu, Ni, and M _III is Sc, Y,
La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, T
b, Dy, Ho, Er, Tm, Yb, Lu, Al, G
a, In represents at least one trivalent metal of In,
X ′, X ″ represent at least one halogen of F, Cl, Br, I, and A represents Eu, Tb, Ce, Tm, D
y, Pr, Ho, Nd, Yb, Er, Gd, Lu, S
at least one of m, Y, Tl, Na, Ag, Cu, Mg
A, b, c, where 0 ≦ a <0.5, 0 ≦
It represents a number that satisfies b <0.5 and 0 <c ≦ 0.2. ) An alkali halide phosphor represented by the formula:

In the present invention, an alkali halide phosphor can be particularly preferably used because it is suitable for a vapor deposition method. However, in the present invention, the phosphor is not limited to the above phosphor, and is a phosphor that emits stimulated light when irradiated with radiation and then irradiated with stimulated excitation light, as long as it can be vapor-deposited. And other phosphors can also be used.

FIG. 9 schematically shows an example of a radiation image conversion apparatus constituted by using a radiation image conversion panel manufactured by the method of the present invention, wherein 10 is a radiation generator, 11 is a subject, and 12 is a radiation image conversion apparatus. Panel, 13 is stimulating excitation light source, 14
Is a photoelectric conversion device that detects stimulated emission emitted from the radiation image conversion panel 12, 15 is a reproduction device that reproduces the signal detected by the photoelectric conversion device 14 as an image, and 16 is an image that is reproduced by the reproduction device 15. The display device 17 for displaying is a filter that separates the stimulating light and the stimulating light and transmits only the stimulating light. In this radiation image conversion device,
Radiation from the radiation generator 10 enters the radiation image conversion panel 12 through the subject 11. This incident radiation is absorbed by the stimulable phosphor layer of the radiation image conversion panel 12,
The energy is accumulated, and an accumulation image of the radiation transmission image is formed. Next, this accumulated image is excited by stimulating light from the stimulating light source 13 and emitted as stimulating light. Since the intensity of the emitted stimulating luminescence is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 14 such as a photomultiplier tube, and reproduced as an image by a reproduction device 15, By displaying the image on the display device 16, a radiation transmission image of the subject 11 can be observed.

Hereinafter, more specific examples will be described, but the present invention is not limited to these examples. EXAMPLE 1 As shown in FIG. 1, an aluminum plate having a thickness of 0.5 mm, a size of 100 mm × 100 mm, and a smooth surface was formed at 250 ° C. under an atmospheric pressure of 1 × 10 ⁻⁵ Torr or less. Is fixed in a horizontal position, and an evaporation source 2 made of a stimulable phosphor material (RbBr: 1 × 10 ⁻⁴ Tl) is provided below the deposition surface 1A of the substrate 1. Are arranged so as to be able to revolve around the normal direction of the deposition surface 1A of the substrate 1 as an axis. While revolving the evaporation source 2 in a horizontal plane about the normal direction of the deposition surface 1A as an axis, the evaporation source 2 is evaporated by an electron beam to form a vapor flow, and the stimulable fluorescent light is emitted on the deposition surface 1A of the substrate 1. A body layer was formed. However, the intersection angle (the acute angle) θ between the streamline direction A of the vapor flow and the normal direction at the central portion of the deposition surface of the substrate was set to 45 °. When the obtained stimulable phosphor layer was observed with an electron microscope, the average of the vertical width a was 7 μm and the average of the horizontal width b was 1
It was confirmed that it was composed of fine columnar crystals having a thickness of 1 μm and a thickness of 250 μm. On this stimulable phosphor layer,
The radiation image conversion panel 1 was manufactured by providing a protective layer made of a glass plate via a low refractive index layer made of dried nitrogen gas.

[Embodiment 2] As shown in FIG.
An evaporation source 2 made of the same stimulable phosphor material is fixedly arranged. At a position above the evaporation source 2, a substrate 1 similar to that of the first embodiment is centered on a horizontal plane in a normal direction B at the center thereof. It was arranged so that it could rotate. While rotating the substrate 1 in a horizontal plane with the normal direction B as an axis,
The evaporation source 2 was evaporated by an electron beam to form a vapor flow, and a stimulable phosphor layer was formed on the surface 1A of the substrate 1 on which the evaporation was performed. However, the intersection angle θ was set to 45 °. Observation of the resulting stimulable phosphor layer with an electron microscope revealed that the vertical width a
Has an average of 7 μm, an average width of 11 μm, and a thickness of 25 μm.
It was confirmed that it was composed of fine columnar crystals of 0 μm. Thereafter, a radiation image conversion panel 2 was manufactured in the same manner as in Example 1.

[Embodiment 3] As shown in FIG.
An evaporation source 2 made of the same stimulable phosphor material is fixedly arranged. At a position above the evaporation source 2, a substrate 1 similar to that of the first embodiment is placed on an inclined plane in a normal direction B at the center thereof. It was arranged so that it could rotate around the center. While rotating the substrate 1 in the inclined plane with the normal direction B as an axis,
The evaporation source 2 was evaporated by an electron beam to form a vapor flow, and a stimulable phosphor layer was formed on the surface 1A of the substrate 1 on which the evaporation was performed. However, the intersection angle θ was set to 40 °. Observation of the resulting stimulable phosphor layer with an electron microscope revealed that the vertical width a
Is 8 μm, the average width b is 11 μm, and the film thickness is 25 μm.
It was confirmed that it was composed of fine columnar crystals of 0 μm. Thereafter, a radiation image conversion panel 3 was manufactured in the same manner as in Example 1.

[Fourth Embodiment] As shown in FIG.
An annular evaporation source 2 made of a stimulable phosphor material similar to the above is fixedly arranged in a horizontal position, and an electron beam generator 3 is arranged at the center of the annular evaporation source 2.
, The substrate 1 similar to that of Example 1 was fixedly arranged in a horizontal posture. The irradiation position of the electron beam 3A from the electron beam generator 3 is sequentially moved along the circumference of the annular evaporation source 2 to evaporate the evaporation source 2 to form a vapor flow, and the surface of the substrate 1 to be evaporated. A stimulable phosphor layer was formed on 1A. However, the intersection angle θ was set to 40 °. Observation of the resulting stimulable phosphor layer with an electron microscope revealed that the vertical width a
Is 8 μm, the average width b is 11 μm, and the film thickness is 25 μm.
It was confirmed that it was composed of fine columnar crystals of 0 μm. Thereafter, a radiation image conversion panel 4 was manufactured in the same manner as in Example 1.

Comparative Example 1 As shown in FIG. 10, an evaporation source 2 made of the same stimulable phosphor material as in Example 1 was fixedly arranged. The substrate 1 is fixedly arranged so that it cannot rotate on an inclined plane where the intersection angle θ is 40 °. The evaporation source 2 was evaporated by an electron beam to form a vapor flow, and a stimulable phosphor layer was formed on the surface 1A of the substrate 1 on which the evaporation was performed. Observation of the resulting stimulable phosphor layer with an electron microscope revealed that the average of the vertical width a was 6 μm, the average of the horizontal width b was 26 μm, and the film thickness was 250 μm.
It was confirmed that it was composed of a wide range of plate-like crystals. Hereinafter, the radiation image conversion panel a is set in the same manner as in the first embodiment.
Was manufactured.

Comparative Example 2 As shown in FIG. 11, an evaporation source 2 made of the same stimulable phosphor material as in Example 1 was fixedly arranged. A substrate 1 similar to that described above was arranged so as to be able to rotate around a normal direction B at the center thereof in the horizontal plane. However, the evaporation source 2 was disposed immediately below the center of the deposition surface 1A of the substrate 1 in the normal direction. While rotating the substrate 1 in a horizontal plane about the normal direction B as the axis, the evaporation source 2 is evaporated by an electron beam to form a vapor flow, and a stimulable phosphor layer is formed on the deposition surface 1A of the substrate 1. did. When the obtained stimulable phosphor layer was observed with an electron microscope, it was confirmed that no columnar crystal was formed. Thereafter, a radiation image conversion panel b was manufactured in the same manner as in Example 1.

Evaluation Radiation image conversion panels 1-4 manufactured as described above
A radiation image conversion apparatus having the configuration shown in FIG. 9 is used to perform a test for actually forming a radiation image by using the radiation image conversion panels a and b for comparison, respectively. The sex was examined.

Sharpness After attaching the CTF chart to the radiation image conversion panel,
After irradiating X-rays with a tube voltage of 80 kV _PP at 10 mR (distance from the tube to the panel: 1.5 m), the substrate is scanned with a semiconductor laser beam (oscillation wavelength: 780 nm, beam diameter: 100 μm) to stimulate excitation, and CTF is excited. The chart image was read as stimulated emission emitted from the stimulable phosphor layer, and photoelectrically converted by a photodetector (photomultiplier) to obtain an image signal. Based on this signal value, the modulation transfer function (MTF) of the image was examined, and the sharpness of the radiation image was evaluated as a relative value. The MTF is a value when the spatial frequency is 3 cycles / mm. The above results are shown in Table 1 below.

[0043]

[Table 1]

As is clear from Table 1, according to the production method of the present invention, the radiation image is excellent in sharpness, the sharpness does not change much depending on the reading direction, and the radiation image has good uniformity in image quality. An image conversion panel is obtained.

[0045]

As described above in detail, according to the present invention, it is possible to form a stimulable phosphor layer composed of a columnar crystal having a narrow width and high accuracy, and to provide excellent radiation image sharpness. In addition, since the change in sharpness depending on the reading direction is small, it is possible to manufacture a good radiation image conversion panel in terms of uniformity of image quality.

[Brief description of the drawings]

FIG. 1 is a view showing a production example of a stimulable phosphor layer.

FIG. 2 is a view showing another example of manufacturing a stimulable phosphor layer.

FIG. 3 is a view showing another example of manufacturing a stimulable phosphor layer.

FIG. 4 is a view showing another example of manufacturing a stimulable phosphor layer.

FIG. 5 is an explanatory diagram of an intersection angle φ between a sum vector of vapor flow vectors and a normal direction of a surface to be vapor-deposited.

FIG. 6 is a cross-sectional view schematically showing a stimulable phosphor layer made of a columnar crystal.

FIG. 7 is a perspective view schematically showing a stimulable phosphor layer made of a columnar crystal.

FIG. 8 is a cross-sectional view showing a specific configuration example of the radiation image conversion panel.

FIG. 9 is an explanatory diagram schematically showing an example of a radiation image conversion apparatus.

FIG. 10 is an explanatory diagram of Comparative Example 1.

FIG. 11 is an explanatory diagram of Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Evaporation source 3 Electron beam generator 4 Stimulable phosphor layer 5 Columnar crystal 6 Crack 7 Protective layer 8 Spacer 9 Low refractive index layer 10 Radiation generator 11 Subject 12 Radiation image conversion panel 13 Stimulation excitation light source 14 Photoelectric Conversion device 15 Reproduction device 16 Display device 17 Filter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21K 4/00

Claims (1)

(57) [Claims] 1. A method for manufacturing a radiation image conversion panel, comprising a step of vapor-depositing a stimulable phosphor on a surface of a substrate using a vapor flow to form at least one stimulable phosphor layer. The method further comprises vapor-depositing a stimulable phosphor on the deposition surface of the substrate while relatively rotating the streamline direction of the vapor flow around the normal direction of the deposition surface of the substrate. Of manufacturing a radiation image conversion panel.