JP3130632B2 - 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 radiation image conversion panel, and more particularly, to a radiation image conversion panel having a stimulable phosphor layer whose crystal lattice planes are aligned.

[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 taking out an image directly from the phosphor layer without using a film coated with a silver salt, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or heat energy. Then, a method has been proposed in which 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 disclose radiation image conversion using a stimulable phosphor and using visible light or infrared light as stimulating excitation light. The method is shown. This method
A radiation image conversion panel having a stimulable phosphor layer formed on a substrate is used. Radiation transmitted through a subject is applied to the stimulable phosphor layer of the radiation image conversion panel, and radiation of each part of the subject is irradiated. A latent image is formed by accumulating radiation energy corresponding to the transmittance, and thereafter the stimulable phosphor layer is scanned with stimulating excitation light to emit the radiation energy accumulated in each part as stimulating light. The optical signal based on the intensity of the light is photoelectrically converted, for example, and is imaged by an image reproducing device. 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 has a radiation absorption rate and a light conversion rate (both of which are the same as in the case of the radiography method using a fluorescent screen described above). (Hereinafter, referred to as “radiation sensitivity”) and high image sharpness.

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 rather by the stimulable phosphor. 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.

[0005]

However, even in the above-mentioned prior art, there is still a problem that the radiation sensitivity and the sharpness of an image are insufficient. In other words, in the stimulable phosphor layer, by forming columnar crystallization or cracks extending in a direction perpendicular to the substrate surface, even if an attempt is made to provide a waveguide effect of stimulating excitation light, the crystal inside the crystal is If the growth direction is non-uniform or if there are many defects and grain boundaries, the stimulating light will be scattered and the sharpness will not be sufficiently improved. Further, the stimulated emission is also scattered, so that the sensitivity is not sufficiently increased. Then, an object of the present invention is to provide a radiation image conversion panel excellent in radiation sensitivity and image sharpness.

[0006]

A radiation image conversion panel according to the present invention is a radiation image conversion panel having at least one stimulable phosphor layer on a substrate, wherein the stimulable phosphor layer has a growth rate. The second peak intensity I ₂ and the first peak in the X-ray diffraction pattern when the crystal lattice plane perpendicular to the fastest direction is measured by an X-ray diffractometer of a powder method at an X-ray incident angle of 10 ° to 35 °. as the ratio I ₂ / I ₁ of the intensity I ₁ is 0.3 or less, and a direction of crystal lattice planes are aligned.

Hereinafter, the present invention will be described specifically. In the present invention, the I ₂ / I ₁ is measured as follows. FIG. 1 shows the relationship between the radiation image conversion panel and the X-ray incident direction. The X-ray incident angle refers to the stimulable phosphor layer 1
1 is an acute angle θ between a plane perpendicular to the direction of the highest growth rate and the X-ray incidence direction. The direction of the highest growth rate when the stimulable phosphor layer 11 is formed is usually a direction perpendicular to the substrate 10 as shown in FIG. 1A, but as shown in FIG. 1B. The direction may be inclined at an angle φ with respect to the direction perpendicular to the substrate 10. This θ is 1
X-ray source 12 while changing in the range of 0 ° to 35 °
In the X-ray diffraction pattern obtained by measuring the amount of X-rays reaching the X-ray detector 13 by making X-rays incident on the stimulable phosphor layer 11 from
The peak intensity I ₁ and the peak intensity indicating the second intensity are defined as the second peak intensity I ₂ , and the ratio I ₂ / I ₁ is obtained. X-rays use CuKα (1.54 °). Further, for example, when the crystal lattice planes are synonymous, such as the (200) plane and the (400) plane, only those having high peak intensities are handled, and peaks relating to other synonymous crystal lattice planes are ignored.

In the present invention, in order to increase the radiation sensitivity and the sharpness of the image, the ratio I ₂ / I ₁ needs to be 0.3 or less, and particularly preferably 0.1 or less. When the ratio I ₂ / I ₁ exceeds 0.3, the radiation sensitivity and the sharpness of the image decrease as will be understood from the description of the comparative examples described later. In the present invention,
From the viewpoint of further improving radiation sensitivity and sharpness, the crystal lattice planes indicated by the first peak are (200) planes, (22)
The (0) plane, the (222) plane or the (422) plane is preferable, and the (200) plane is particularly preferable.

As a method of forming the stimulable phosphor layer, the method of forming the stimulable phosphor layer while growing the crystal in the thickness direction, for example, a vapor phase deposition method is preferable from the viewpoint that the crystal growth directions are aligned. . The stimulable phosphor layer preferably has a columnar crystal structure from the viewpoint of enhancing radiation sensitivity and sharpness, and from this point as well, is preferably formed by a vapor deposition method. Examples of the vapor deposition method include a vacuum deposition method (hereinafter, simply referred to as a “deposition method”), a sputtering method, a CVD method, an ion plating method, and the like. The resistance heating evaporation method is preferred. According to the vapor deposition method, a crystal plane in which crystal growth is promoted and a plane in which crystal growth is suppressed are generated by selecting manufacturing conditions, so that a large number of fine particles are formed in the thickness direction of the stimulable phosphor layer. It is possible to form a stimulable phosphor layer having a fine columnar structure having various cracks.

For example, when a stimulable phosphor layer is formed by a vapor deposition method, the substrate is placed in a vapor deposition apparatus, and then the inside of the vapor deposition apparatus is evacuated to a predetermined degree of vacuum. Next, the substrate is heated to a predetermined temperature, and at least one kind of the stimulable phosphor is heated and evaporated by a method such as a resistance heating method or an electron beam method, so that the stimulable phosphor is deposited on the surface of the substrate at a predetermined temperature. Deposit to thickness. In the vapor deposition method, the value of I ₂ / I ₁ can be controlled by appropriately adjusting the temperature of the substrate, the atmospheric pressure, the vapor deposition rate, the direction of the vapor flow of the evaporation source with respect to the substrate surface, and the like. In the vapor deposition step, the stimulable phosphor layer can be formed in a plurality of times. In the evaporation step, co-evaporation can be performed using a plurality of resistance heaters or electron beams. After the vapor deposition, a protective layer may be provided on the surface of the stimulable phosphor layer on the side opposite to the substrate side, if necessary, directly or via a gap.

In the vapor deposition method, a stimulable phosphor raw material is co-deposited by using a plurality of resistance heaters or electron beams to synthesize a desired stimulable phosphor on the surface of the substrate, and at the same time, to stimulate stimulable phosphor. It is also possible to form a luminescent phosphor layer. Further, in the vapor deposition method, at the time of vapor deposition, an object to be deposited (a support or a protective layer) may be cooled or heated as necessary. Further, the stimulable phosphor layer may be subjected to a heat treatment after the deposition is completed. In the vapor deposition method, O ₂ ,
Reactive deposition may be performed by introducing a gas such as H ₂ .

The thickness of the stimulable phosphor layer varies depending on the intended radiation sensitivity of the radiation image conversion panel, the kind of the stimulable phosphor and the like, but is preferably 30 to 1000 μm, particularly preferably 50 to 500 μm. When the layer thickness of the stimulable phosphor layer is too small, the radiation sensitivity decreases because the radiation absorptivity decreases, and when the layer thickness is too large, the lateral spread of the stimulable excitation light increases. The sharpness of the image deteriorates.

In the present invention, it is preferable to produce the stimulable phosphor layer by an oblique deposition method. In this case, the average incident angle of the vapor flow with respect to the normal to the substrate surface is 20 to 60 °
Preferably, the average of the angles in the crystal growth direction is 5 to 40 °
Is preferred. According to such an oblique deposition method, a stimulable phosphor layer having higher radiation sensitivity and sharpness can be obtained.

In the present invention, a 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. Refers to a phosphor that exhibits stimulated emission corresponding to the dose of the first light or high-energy radiation, but from a practical viewpoint, a phosphor that exhibits 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 is particularly preferable. The following can be used as the stimulable phosphor constituting the stimulable phosphor layer. (1) SrS: Ce, Sm, SrS: Eu, Sm, La ₂ O ₂ described in US Pat. No. 3,859,527.
S: Eu, Sm, (Zn, Cd) S: Mn, X (where X represents a halogen). (2) In formula described in JP 55-12142 Patent Publication No. _{BaO · xAl 2 O 3: Eu} ( here, x is 0.8 ≦ x
Represents a number that satisfies ≦ 10. Barium aluminate phosphor represented by). (3) The general formula described in JP-A-55-12142 describes M ^I
O · xSiO _2: A (however, M ^I is, Mg, Ca, S
r, Zn, Cd, Ba, where 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:

(4) The general formula described in JP-A-55-12143 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, xy ≠ 0, 1
It represents a number satisfying 0 ⁻⁶ ≦ e ≦ 5 × 10 ⁻² . The phosphor represented by). (5) The general formula described in JP-A-55-12144 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). (6) When the general formula described in JP-A-55-12145 is (Ba _1-x (M ^I ) _x ) FX: yA (where M ^I is
X represents at least one of Mg, Ca, Sr, Zn, and Cd; X represents at least one of Cl, Br, and I;
Are 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). (7) The general formula described in JP-A-55-160078 is M ^I FX · xA: yLn (where M ^I is Mg, C
a, Ba, Sr, Zn, Cd.
A is BeO, MgO, CaO, SrO, BaO, Zn
O, 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 ,
Ln represents at least one of Nb ₂ O ₅ , Ta ₂ O ₅ , and ThO ₂ , and Ln represents Eu, Tb, Ce, Tm, Dy, Pr,
Ho, Nd, Yb, Er, Sm, Gd, represents at least one of Cl, Br, I, x, y represents 5 × 10 ⁻⁵ ≦ x ≦ 0.5, 0 <y ≦ 0.
Represents a number satisfying 2. ) A rare earth element-activated divalent metal fluorohalide phosphor represented by the formula:

(8) 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 (where M,
N is Mg, Ca, Sr, Ba, Zn, Cd, respectively.
X represents at least one of F, Cl, Br, I, and A represents Eu, Tb, Ce, T
m, Dy, Pr, Ho, Nd, Yb, Er, Sb, T
1, at least one of Mn and Sn, wherein x and y are 0
<X ≦ 6, 0 ≦ y ≦ 1. The phosphor represented by). (9) General formula M described in JP-A-60-84381
^I X ₂ · aM ^I X ' ₂ : xEu ²⁺ (where M ^I is B
a, Sr, Ca represents at least one alkaline earth metal, and X and X ′ are at least one of Cl, Br, I
X <X ', wherein a represents 0.
Represents a number satisfying 1 ≦ a ≦ 10.0, and x is 0 <x ≦
Represents a number satisfying 0.2. ) A divalent europium activated alkaline earth metal halide phosphor represented by the following formula: (10) The general formula MX ₂ · aMX ′ ₂ : bEu ²⁺ described in JP-A-63-27588 (where M is Ca,
X and X ′ represent at least one halogen of Cl, Br and I, and a represents a number satisfying 0.5 ≦ a ≦ 1.8. And b represents a number that satisfies 10 ⁻⁴ ≦ b ≦ 10 ⁻² . ) A divalent europium activated alkaline earth metal halide phosphor represented by the following formula:

(11) A bivalent europium activation represented by the general formula BaX ₂ : Eu (X is a halogen) described on page 1086 of the 51st Annual Meeting of the Japan Society of Applied Physics (Autumn 1990) Barium halide phosphor. (12) In formula described in JP 61-72088 JP ^{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, Mg, C
a, Sr, Ba, Zn, Cd, Cu, Ni represents at least one divalent metal, and M ^III represents Sc, Y, La,
Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
y, Ho, Er, Tm, Yb, Lu, Al, Ga, In
Represents at least one trivalent metal of X, X ′, X ″
Represents at least one halogen of F, Cl, Br, I, and A represents Eu, Tb, Ce, Tm, Dy, Pr, H
o, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl,
Represents at least one metal of Na, Ag, Cu and Mg, wherein a, b and c are 0 <a <0.5, 0 ≦ b <0.5,
Represents a number satisfying 0 <c ≦ 0.2. ) An alkali halide phosphor represented by the formula:

In the present invention, in particular, alkali halide phosphors are preferable because the phosphor layer can be easily formed by vapor deposition such as vapor deposition. However, in the present invention, the phosphor is not limited to the above, and may be a phosphor that emits light or radiation and then stimulates, preferably emits photostimulated light when irradiated with photostimulated excitation light. Other phosphors can be used as long as it is used. In the present invention, a plurality of stimulable phosphor layers may be used to form a stimulable phosphor layer group including two or more stimulable phosphor layers. In this case, the stimulable phosphor contained in each stimulable phosphor layer may be the same or different.

In the present invention, examples of the substrate include a ceramic plate such as alumina and crystallized glass, a glass plate such as quartz glass and chemically strengthened glass, aluminum, and the like.
A metal plate of iron, copper, chromium or the like or a metal plate having a coating layer of the metal oxide is preferable, but plastics such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, polycarbonate film, and triacetate film are preferable. It may be a film. In addition, the layer thickness of these substrates differs depending on the material of the substrate to be used and the like.
Generally, it is preferably from 100 to 5000 μm, and particularly preferably from 200 to 2000 μm from the viewpoint of convenience of 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. The surface of the substrate is disclosed in Japanese Patent Laid-Open No. 61-142.
The surface may have an uneven surface as described in JP-A-497-497, or a structure in which isolated tile-like plates are spread as described in JP-A-61-142498. In addition, most of the substrate may be made smooth, and only the peripheral portion may be made rough for the purpose of enhancing the 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. Further, a light reflection layer, a light absorption layer, an adhesive layer, and the like may be provided on these substrates as needed.

If necessary, a protective layer for physically or chemically protecting the stimulable phosphor layer may be provided on the surface of the stimulable phosphor layer. This protective layer may be formed by directly applying a coating solution for the protective layer on the stimulable phosphor layer, or by bonding a separately formed protective layer on the stimulable phosphor layer. Is also good. Further, a resin that is cured by radiation and / or heat as proposed in JP-A-61-176900 may be used. As the material of the protective layer, cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polypropylene, polyvinylidene chloride, nylon, polytetrafluoroethylene,
Examples include poly (ethylene trifluoride), ethylene tetrafluoride / propylene hexafluoride copolymer, vinylidene chloride / vinyl chloride copolymer, vinylidene chloride / acrylonitrile copolymer and the like.

The protective layer is made of SiC, SiO ₂ , SiN, Al by vacuum evaporation, sputtering or the like.
_It may be formed by laminating inorganic substances such as ₂ O ₃ . Also,
What can be formed into a sheet having excellent translucency can be used as a protective layer by closely adhering it on the stimulable phosphor layer or disposing it at a distance. The protective layer desirably exhibits high light transmittance in a wide wavelength range in order to efficiently transmit stimulated excitation light and stimulated emission, 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 is 3
It shows a light transmittance of 80% or more in a wavelength range of 30 nm to 2.6 μm, and quartz glass shows a high light transmittance even at a shorter wavelength.

Further, it is preferable to provide an anti-reflection layer such as MgF _{2 on} the surface of the protective layer, because it has the effects of efficiently transmitting stimulated excitation light and stimulated emission and reducing a decrease in sharpness. Moreover, the thickness of the protective layer is 50 μm to 5 m.
m, preferably from 100 μm to 3 mm. When the protective layer is disposed at a distance from the stimulable phosphor layer,
It is preferable to provide a spacer between the substrate and the protective layer so as to surround the phosphor layer, and such a spacer is capable of holding the stimulable phosphor layer in a state shielded from the external atmosphere. There is no particular limitation as long as glass, ceramics, metal, plastic, etc. can be used,
The thickness is preferably equal to or greater than the thickness of the stimulable phosphor layer.

FIG. 2 schematically shows an example of a radiation image conversion apparatus constituted by using the radiation image conversion panel of the present invention, wherein 21 is a radiation generator, 22 is a subject, 23 is a radiation image conversion panel, and 24 is bright. Depleted excitation light source, 25 is a photoelectric conversion device for detecting stimulated emission emitted from the radiation image conversion panel 23, 26 is a reproducing device for reproducing a signal detected by the photoelectric conversion device 25 as an image, and 27 is a reproducing device 26
Is a filter that separates the photostimulated light and the photostimulated light and transmits only the photostimulated light. In the radiation image conversion apparatus shown in FIG.
Through the radiation image conversion panel 23. The incident radiation RI is absorbed by the stimulable phosphor layer of the radiation image conversion panel 23, its energy is accumulated, and an accumulation image of the radiation transmission image is formed. Next, the accumulated image is excited by stimulating light from the stimulating light source 24 and emitted as stimulating light. Since the intensity of the emitted stimulating light is proportional to the amount of the accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 25 such as a photomultiplier tube, and reproduced as an image by a reproduction device 26. By displaying the image on the display device 27, a radiation transmission image of the subject 22 can be observed.

[0025]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these embodiments. Example 1 RbBr as an evaporation source: 0.002 Tl
Br (a stimulable phosphor material) is vapor-deposited on a substrate made of an aluminum plate having a thickness of 0.5 mm and a smooth surface by an electron beam vapor deposition method, and a stimulable phosphor having a film thickness of about 200 μm is deposited. A body layer was formed. However, the temperature of the substrate was set to 300 ° C., the atmospheric pressure was set to 3 × 10 ⁻³ Torr by introducing N _2, and the deposition rate of the stimulable phosphor layer was set to 10 μm / min. The average direction of the vapor flow of the raw material for the stimulable phosphor was made substantially perpendicular to the substrate surface. As shown in FIG. 3, the obtained stimulable phosphor layer 31 had a columnar crystal structure extending substantially perpendicular to the surface of the substrate 30.

The direction in which the growth rate of the stimulable phosphor layer is the fastest (in this embodiment, the direction perpendicular to the substrate surface)
X-ray diffractometer of powder method using intrinsic X-ray CuKα (1.54 °) of copper with respect to a crystal lattice plane perpendicular to the crystal plane, that is, a crystal lattice plane parallel to the substrate plane.
A ”indicates that the X-ray has an X-ray incidence angle in the range of 10 ° to 35 °.
When the X-ray diffraction pattern was measured, the most strongly oriented crystal lattice plane (first oriented plane) was the (422) plane, and the peak intensity of the second oriented plane relative to its peak intensity (first peak intensity) I ₁ . (second peak intensity) ratio of I ₂ I ₂ / I ₁
Was 0.06. This X-ray diffraction pattern is shown in FIG. Using the stimulable phosphor layer obtained as described above, a radiation image conversion panel of the present invention (hereinafter abbreviated as “conversion panel”) is manufactured, and the radiation sensitivity and sharpness are determined by the following method. Upon examination, the radiation sensitivity was 1.4.
2. The sharpness was 52%.

[Radiation sensitivity] A tube voltage of 80 k is applied to the conversion panel.
X-ray of V _PP is 10mR (distance from tube to panel:
1.5 m) and then irradiate the semiconductor laser light (oscillation wavelength 78
(0 nm, beam diameter: 100 μmφ) to stimulate stimulus excitation, read out stimulable luminescence emitted from the stimulable phosphor layer, and perform photoelectric conversion with a photodetector (photomultiplier tube) to obtain a signal. The relative sensitivity of this signal value is used as radiation sensitivity. [Sharpness] After attaching a CTF chart to the conversion panel, X-rays with a tube voltage of 80 kV _PP were irradiated with 10 mR (distance from the tube to the panel: 1.5 m), and then a semiconductor laser beam (oscillation wavelength: 780 nm, (Beam diameter: 100 μmφ)
Scans with, stimulates photostimulation, reads the CTF chart image as photostimulated light emitted from the photostimulable phosphor layer,
(Photomultiplier tube) to perform photoelectric conversion to obtain an image signal. With this signal value, the modulation transfer function (MTF) of the image is examined,
The sharpness of the image was evaluated. Note that the modulation transfer function (MT
F) is a value when the spatial frequency is 3 cycles / mm.

Example 2 A stimulable phosphor layer was manufactured in the same manner as in Example 1 except that the substrate temperature was changed to 250 ° C. In this stimulable phosphor layer, the first orientation plane is the (422) plane, and I ₂ / I ₁ is 0.16.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. As a result, the radiation sensitivity was 1.28 and the sharpness was 51%. there were.

Example 3 A stimulable phosphor layer was manufactured in the same manner as in Example 1 except that the substrate temperature was changed to 200 ° C. In this stimulable phosphor layer, the first orientation plane is the (422) plane, and I ₂ / I ₁ is 0.26.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. As a result, the radiation sensitivity was 1.17 and the sharpness was 50%. there were.

Example 4 A stimulable phosphor layer was manufactured in the same manner as in Example 1 except that the atmospheric pressure was changed to 1.0 × 10 ⁻⁴ Torr. In this stimulable phosphor layer, the first orientation plane is the (220) plane, and I ₂
/ I ₁ was 0.02. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 1,
When evaluated in the same manner as in Example 1, the radiation sensitivity was 1.62 and the sharpness was 48%.

Example 5 A stimulable phosphor layer was manufactured in the same manner as in Example 4 except that the substrate temperature was changed to 250 ° C. In this stimulable phosphor layer, the first orientation plane is the (220) plane, and I ₂ / I ₁ is 0.21.
Met. FIG. 5 shows the obtained X-ray diffraction pattern. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 4, and evaluated in the same manner as in Example 4. The radiation sensitivity was 1.41 and the sharpness was 46%. there were.

Example 6 A stimulable phosphor layer was manufactured in the same manner as in Example 4 except that the substrate temperature was changed to 200 ° C. In this stimulable phosphor layer, the first orientation plane is the (220) plane, and I ₂ / I ₁ is 0.28.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 4, and evaluated in the same manner as in Example 4. The radiation sensitivity was 1.25 and the sharpness was 45%. there were.

Example 7 In Example 1, the substrate temperature was set to 250 ° C., the introduction of N ₂ was stopped, and the atmospheric pressure was increased to 10 ° C.
^-6 Torr, and the average direction of the vapor flow of the raw material for the stimulable phosphor is 40 ° with respect to the direction perpendicular to the substrate surface.
A stimulable phosphor layer was produced in the same manner as in Example 1 except that the vapor deposition was carried out at a positional relationship of an angle of °. As shown in FIG. 6, the obtained stimulable phosphor layer 61 is
A columnar crystal structure extending in a direction inclined by about 20 ° with respect to a direction perpendicular to the plane was obtained. The direction inclined by about 20 ° with respect to the direction perpendicular to the surface of the substrate 60 is the direction in which the growth rate is the fastest in this embodiment. FIG. 7 shows the obtained X-ray diffraction pattern. In this stimulable phosphor layer, the first
The orientation plane was the (200) plane, and I ₂ / I ₁ was 0. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. As a result, the radiation sensitivity was 2.10 and the sharpness was 54%.
Met.

[Embodiment 8] The vapor deposition was performed in the same manner as in Embodiment 7, except that the average direction of the vapor flow of the stimulable phosphor material was at an angle of about 20 ° to the direction perpendicular to the substrate surface. A stimulable phosphor layer was manufactured in the same manner as in Example 7 except that the above was performed. The resulting stimulable phosphor layer had a columnar crystal structure extending in a direction inclined by about 10 ° with respect to a direction perpendicular to the substrate surface. The direction inclined by about 10 ° with respect to the direction perpendicular to the substrate surface is the direction of the highest growth rate in this embodiment. In this stimulable phosphor layer, the first orientation plane was the (200) plane, and I ₂ / I ₁ was 0.04. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 7, and evaluated in the same manner as in Example 7. As a result, the radiation sensitivity was 1.86 and the sharpness was 52%.
Met.

Example 9 The raw material of the stimulable phosphor was Rb
I: The stimulable phosphor layer was manufactured in the same manner as in Example 1 except that the substrate temperature was changed to 0.002 TlI and the substrate temperature was changed to 270 ° C. In this stimulable phosphor layer, the first orientation plane is (4
22) plane, and I ₂ / I ₁ was 0.04. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. As a result, the radiation sensitivity was 1.59 and the sharpness was 49%. there were.

Example 10 A stimulable phosphor layer was manufactured in the same manner as in Example 9 except that the substrate temperature was changed to 220 ° C. In this stimulable phosphor layer, the first orientation plane is the (422) plane, and I ₂ / I ₁ is 0.16.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 9 and evaluated in the same manner as in Example 9. The radiation sensitivity was 1.40 and the sharpness was 47%. there were.

Example 11 A stimulable phosphor layer was manufactured in the same manner as in Example 9 except that the substrate temperature was changed to 170 ° C. In this stimulable phosphor layer, the first orientation plane is the (422) plane, and I ₂ / I ₁ is 0.27.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 9 and evaluated in the same manner as in Example 9. As a result, the radiation sensitivity was 1.25 and the sharpness was 46%. there were.

Example 12 A stimulable phosphor layer was manufactured in the same manner as in Example 9 except that the atmospheric pressure was changed to 1.0 × 10 ⁻⁴ Torr. In this stimulable phosphor layer, the first orientation plane is the (220) plane, and I ₂
/ I ₁ was 0.02. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 9,
When evaluated in the same manner as in Example 9, the radiation sensitivity was 1.81 and the sharpness was 45%.

Example 13 A stimulable phosphor layer was manufactured in the same manner as in Example 12, except that the substrate temperature was changed to 220 ° C. In this stimulable phosphor layer, the first orientation plane was the (220) plane, and I ₂ / I ₁ was 0.20. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 12, and evaluated in the same manner as in Example 12. The radiation sensitivity was 1.5.
7. The sharpness was 43%.

Example 14 A stimulable phosphor layer was produced in the same manner as in Example 12, except that the substrate temperature was changed to 170 ° C. In this stimulable phosphor layer, the first orientation plane was the (220) plane, and I ₂ / I ₁ was 0.27. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 12, and evaluated in the same manner as in Example 12. The radiation sensitivity was 1.3.
4. The sharpness was 42%.

Example 15 The raw material of the stimulable phosphor was Rb
I: A stimulable phosphor layer was produced in the same manner as in Example 7, except that the substrate temperature was changed to 0.002 TlI and the substrate temperature was set to 220 ° C. In this stimulable phosphor layer, the first orientation plane is (2
00) plane, and I ₂ / I ₁ was 0. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 7, and evaluated in the same manner as in Example 7.
Radiation sensitivity was 2.35 and sharpness was 51%.

Example 16 The raw material of the stimulable phosphor was Rb
I: The stimulable phosphor layer was manufactured in the same manner as in Example 8, except that the substrate temperature was changed to 0.002 TlI and the substrate temperature was set to 220 ° C. In this stimulable phosphor layer, the first orientation plane is (2
00) plane, and I ₂ / I ₁ was 0.03. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 8, and evaluated in the same manner as in Example 8. As a result, the radiation sensitivity was 2.07 and the sharpness was 49%. there were.

Comparative Example 1 A stimulable phosphor layer was manufactured in the same manner as in Example 1 except that the substrate temperature was changed to 50 ° C. In this stimulable phosphor layer, the first
The orientation plane was the (200) plane, and I ₂ / I ₁ was 0.78. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The radiation sensitivity was 1.0 and the sharpness was 42.
%Met.

Comparative Example 2 A stimulable phosphor layer was manufactured in the same manner as in Example 4 except that the substrate temperature was changed to 50 ° C. In this stimulable phosphor layer, the first
The orientation plane was (200) plane, and I ₂ / I ₁ was 0.73. FIG. 8 shows the obtained X-ray diffraction pattern. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 4, and evaluated in the same manner as in Example 4. As a result, the radiation sensitivity was 1.07 and the sharpness was 40%. .

Comparative Example 3 A stimulable phosphor layer was produced in the same manner as in Example 9 except that the substrate temperature was changed to 50 ° C. In this stimulable phosphor layer, the first
The orientation plane was the (200) plane, and I ₂ / I ₁ was 0.75. Using this stimulable phosphor layer, a conversion panel of the present invention was prepared in the same manner as in Example 9 and evaluated in the same manner as in Example 9. As a result, the radiation sensitivity was 1.12 and the sharpness was 3
9%.

Comparative Example 4 A stimulable phosphor layer was manufactured in the same manner as in Example 12, except that the substrate temperature was changed to 50 ° C. In this stimulable phosphor layer, the first orientation plane is the (200) plane, and I ₂ / I ₁ is 0.68.
Met. Using this stimulable phosphor layer, a conversion panel of the present invention was produced in the same manner as in Example 12, and evaluated in the same manner as in Example 12. The radiation sensitivity was 1.16 and the sharpness was 38%. there were.

[0047]

According to the radiation image conversion panel of the present invention, since the directions of the crystal lattice planes of the stimulable phosphor layer are aligned, the sharpness of the image and the radiation sensitivity are improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for measuring an X-ray diffraction pattern.

FIG. 2 is a schematic diagram of an example of a radiation image conversion device configured using the radiation image conversion panel of the present invention.

FIG. 3 is a schematic view showing a columnar crystal structure of a stimulable phosphor layer obtained in Example 1.

FIG. 4 is a graph of an X-ray diffraction pattern of a stimulable phosphor layer obtained in Example 1.

FIG. 5 is a graph showing an X-ray diffraction pattern of a stimulable phosphor layer obtained in Example 5.

6 is a schematic view showing a columnar crystal structure of a stimulable phosphor layer obtained in Example 7. FIG.

FIG. 7 is a graph showing an X-ray diffraction pattern of a stimulable phosphor layer obtained in Example 7.

FIG. 8 is a graph of an X-ray diffraction pattern of a stimulable phosphor layer obtained in Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Substrate 11 Stimulable phosphor layer 12 X-ray source 13 X-ray detector 21 Radiation generator 22 Subject 23 Radiation image conversion panel 24 Stimulation excitation light source 25 Photoelectric conversion device 26 Reproduction device 27 Display device 28 Filter 30 Substrate 31 Stimulation Phosphor layer 60 substrate 61 stimulable phosphor layer

Claims (1)

(57) [Claims] 1. A radiation image conversion panel having at least one stimulable phosphor layer on a substrate, wherein the stimulable phosphor layer is formed on a crystal lattice plane perpendicular to a direction in which a growth rate is fastest by a powder method. X when measured with an X-ray diffractometer at an X-ray incident angle of 10 ° to 35 °
As the ratio I ₂ / I ₁ of the second peak intensity I ₂ and the first peak intensity I ₁ is less than 0.3 at a linear diffraction pattern,
A radiation image conversion panel wherein the directions of crystal lattice planes are aligned.