JPH0535399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radiation image conversion method using a photostimulable phosphor.

(Prior Art) Radiographic images such as X-ray images are often used for medical purposes. Conventionally, in order to obtain this radiographic image, a so-called radiographic method has been used in which a radiographic film made of a silver salt photosensitive material and an intensifying screen are combined. However, in recent years, with the advancement of radiographic image diagnostic technology, methods of obtaining radiographic images without using radiographic films made of silver salt photosensitive materials have been devised.

Such a method involves causing the radiation transmitted through the subject to be absorbed by some type of phosphor, and then exciting this phosphor with, for example, light or thermal energy, so that the phosphor absorbs the energy accumulated by the absorption. There is a method of emitting the radiation energy in the form of fluorescence, detecting this fluorescence, and creating an image.
Specifically, for example, British Patent No. 1462769 and Japanese Unexamined Patent Publication No. 51-29889 disclose a method of using a heat-stimulable phosphor as the phosphor. This method uses a radiation image conversion panel with a heat-stimulable phosphor layer formed on a support.The heat-stimulable phosphor layer of this radiation image conversion panel absorbs the radiation that has passed through the subject. Then, radiation energy corresponding to the radiation transmittance of each part of the subject is accumulated to form a latent image, and then this heat-stimulable phosphor layer is heated to excite it, and the radiation energy is accumulated in each part of the panel. The accumulated radiation energy is extracted as a light signal, and a radiation image is obtained by varying the intensity of this light.

Also, for example, U.S. Patent No. 3,859,527 and
No. 12144 discloses a method of using a photostimulable phosphor as the phosphor. This method uses a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support. After forming a latent image as described above, this photostimulable phosphor layer is photostimulated. By scanning with light, the radiation energy accumulated in each part of the panel is extracted as a light signal and a radiation image is obtained. This final image may be reproduced as a hard copy or on a CRT.

By the way, at present, there are almost no descriptions regarding the stimulable phosphor layer of the radiation image conversion panel used in such radiation image conversion methods.
Generally, it consists of only one stimulable phosphor layer, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 55-12144. However, when there is only one photostimulable phosphor layer, most of the accumulated radiation energy is released by just one stimulation excitation, and one radiation irradiation causes It was impossible to obtain multiple radiographic image data.

On the other hand, several methods are known for obtaining data of a plurality of radiation images by one radiation irradiation. As a specific method, for example,
No. 56-11399 discloses a method of stacking a plurality of radiation image conversion panels, irradiating them with radiation at the same time, and sequentially stimulating the plurality of radiation image conversion panels to obtain data of a plurality of radiation images. A method is shown. However, this method has the disadvantage that it requires multiple radiation image conversion panels, which makes it cumbersome to handle during radiation irradiation, and that the reading device for obtaining radiation image data is complex and large-scale. Ta.

(Object of the present invention) The present invention has been made in view of the above-mentioned drawbacks of radiation image conversion panels using stimulable phosphors. Therefore, it is an object of the present invention to provide a radiation image conversion method by which a plurality of pieces of radiation image data can be obtained.

Another object of the present invention is to provide a radiation image conversion method that does not cause image shift due to overlay processing or the like.

Still another object of the present invention is to provide a radiation image conversion method that causes less deterioration in image quality due to scratches on the stimulable phosphor layer even after repeated use.

(Structure of the Invention) In order to achieve the above object, the present inventor has conducted intensive research on a radiation image conversion method using a photostimulable phosphor. As a result, each photostimulable phosphor has its own unique photostimulation excitation energy distribution, and the photostimulable luminescence efficiency increases when excited with photostimulation excitation energy matched to the individual photostimulable phosphor. I found that the maximum. That is, by utilizing the above phenomenon, a stimulable phosphor layer containing at least two types of stimulable phosphors whose stimulable luminescence efficiencies have different dependencies on stimulable excitation energy can be formed into a stimulable phosphor layer containing each stimulable phosphor. By excitation multiple times with luminous layer excitation energy matched to the body, multiple radiation images can be obtained with one X-ray irradiation.

Based on this knowledge, an object of the present invention is to provide a radiation image conversion panel having a stimulable phosphor layer containing at least two types of stimulable phosphors whose stimulable luminescence rates are different in dependence on stimulable excitation energy. of,
This is achieved by a radiation image conversion method characterized in that each of the stimulable phosphors is excited with a different stimulable excitation energy corresponding to the stimulable phosphor, and a plurality of radiation images are read out as separate images. .

In addition, in one embodiment of the present invention, it is preferable to use at least one type of heat-stimulable phosphor among the above-mentioned photostimulable phosphors.
It becomes one.

In the present invention, a photostimulable phosphor refers to a photostimulable phosphor that is first irradiated with light or high-energy radiation and then stimulated optically, thermally, mechanically, chemically, or electrically (stimulated excitation). A phosphor that exhibits stimulated luminescence corresponding to the amount of light or high-energy radiation irradiated with it. In particular, those in which the photostimulation occurs optically are called photostimulable phosphors, and those in which the photostimulation occurs thermally are called thermally stimulable phosphors.

Light here includes visible light, ultraviolet light, and infrared light among electromagnetic radiation, and high-energy radiation refers to
rays, gamma rays, beta rays, alpha rays, and neutron rays.

In addition, in the present invention, stimulable phosphors having different stimulable excitation energy in terms of stimulable luminescence efficiency broadly refer to phosphors that require different types of stimulation energy to cause the stimulable phosphor to emit stimulated light. In other words, it refers to phosphors whose photostimulated excitation spectra have different peaks of 50 nm or more.

The present invention will be explained in detail below.

The photostimulable phosphor used in the radiation image conversion panel of the present invention is a phosphor that exhibits stimulated luminescence when stimulated after being irradiated with radiation as described above, and at least two types thereof are used. may be any phosphors as long as they differ in the dependence of their stimulated luminescence rates on stimulated excitation energy.

Examples of combinations of photostimulable phosphors with different dependencies on photostimulable excitation energy include photostimulable phosphors and heat-stimulable phosphors; Examples include, but are not limited to, phosphors that differ from each other by 50 nm or more, and phosphors that have different photostimulation temperatures among heat-stimulable phosphors.

Examples of the photostimulable phosphor used in the radiation image conversion panel of the present invention include BaSO ₄ :A _x (where A is D _y , Tb
and Tm, and x is 0.001
≦x<1 mol%), MgSO ₄ :A _x (where A is H ₀
or Dy, 0.001≦x≦1
Fluorescent substance expressed in mol%), JP-A-1988-
SrSO ₄ :Ax (However, A is
At least one of Dy, Tb and Tm,
x is 0.001≦x<1 mol%), which is described in JP-A-51-29889.
Mn, Dy and Tb in Na ₂ SO ₄ , CaSO ₄ and BaSO ₄ etc.
A phosphor containing at least one of the following, JP-A-Sho
BeO, LiF, described in No. 52-30487,
Fluorescent substances such as MgSO ₄ and CaF ₂ , JP-A-53-39277
Li ₂ B ₄ O ₇ described in JP-A-54-47883: Fluorescent material such as Cu, Ag, Li ₂ O.
(B ₂ O ₂ ) _x : Cu (where x is 2<x≦3), and
Li ₂ O・(B ₂ O ₂ ) _x : Cu, Ag (however, x is 2<x≦3)
etc., SrS:Ce, Sm, SrS:Eu, Sm, La ₂ O ₂ S: Eu, as described in U.S. Pat. No. 3,859,527.
Examples include phosphors represented by Sm and (Zn, Cd)S:Mn, X (where X is a halogen). In addition, ZnS: Cu, Pb described in JP-A-55-12142
Fluorescent material, general formula is BaS・_x Al ₂ O ₃ :Eu (however, 0.8≦x
≦10) barium aluminate phosphor,
and the general formula is M〓O・_x SiO ₂ :A (however, M〓 is Mg,
Ca, Sr, Xn, Cd or Ba, and A is Ce, Tb,
Examples include alkaline earth metal silicate-based phosphors that are at least one of Eu, Tm, Pb, Tl, Bi, and Mn, and x is 0.5≦x≦2.5. In addition, the general formula is (Ba _1-xy Mg _x Ca _y )FX: _l Eu (However, X is at least one of Br and Cl, x, y and l are each 0<x+y≦0.6,
xy≠0 and 10 ^-6 ≦l≦5×10 ^-2 The formula is LnOX: _x A (where Ln is at least one of La, Y, Gd, and Lu)
X represents Cl and/or Br, A represents Ce and/or Tb, and x represents a number satisfying 0<x<0.1. ), the general formula described in JP-A-55-12145 is (Ba _1-x M〓 _x )FX: _y A (where M〓 is Mg, Ca, Sr, Zn and Cd X is at least one of Cl, Br and I, A is Eu, Tb, Ce, Tm, Dy,
At least one of Pr, Ho, Nd, Yd and Er
x and y represent numbers satisfying the conditions 0≦x≦0.6 and 0≦y≦0.2. ), the general formula of which is described in JP-A-55-84389 is BaFX: _x Ce, _y A (where X is at least one of Cl, Br and I, and A is In). , Al, Gd, Sm and
at least one of Sr, and x and y are 0<x≦2×10 ^-1 and 0<y≦5×10 ^{-2 respectively}
It is. ), Japanese Patent Application Laid-Open No. 1986-
The general formula described in No. 160078 is M〓FX・_x A: _y Ln (However, M〓 is at least one of Mg, Ca, Br, Zn, and Cd, and A is BeO, MgO, CaO, SrO,
BaO, ZnO, _{Al2O3 , Y2O3 , La2O3 , In2O3 ,
SiO2} , _TiO2 , _ZrO2 , _GeO2 , _SnO2 , _{Nb2O5 ,}
At least one of TTa ₂ O ₅ and ThO ₂ , Ln
are Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb,
At least one of Er, Sm and Gd,
X is at least one of Cl, Br, and I, and x and y are numbers satisfying the conditions of 5×10 ⁻⁵ ≦x≦0.5 and 0<y≦0.2, respectively. ) Rare earth element-activated divalent metal fluorohalide phosphors, whose general formulas are ZnS:A, CaS:A, (Zn,
Cd) Fluorescent material represented by S: A, ZnS: A, X and CdS: A, −
General formula [] or [] described in No. 148285, General formula [] _x M ₃ (PO ₄ ) ₂・NX ₂ : _y A General formula [] M ₃ (PO ₄ ) ₂ : _y A (in the formula , M and N are respectively Mg, Ca, Sr, Ba,
At least one of Zn and Cd, X is F, Cl,
At least one of Br and I, A is Eu, Tb,
Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sb,
Represents at least one of Tl, Mn and Sn.
Furthermore, x and y are numbers that satisfy the conditions 0<x≦6 and 0≦y≦1. ) represented phosphor and the general formula [] or [] general formula [] nReX ₃・mAX′ ₂ : _x Eu general formula [] nReX ₃・mAX′ ₂ : _x Eu, ySm (in the formula, Re is La , Gd, Y, and Lu; A represents an alkaline earth metal; and at least one of Ba, Sr, and Ca; X and X' represent at least one of F, Cl, and Br; x and y
are 1×10 ^-4 <x<3×10 ^-1 , 1×10 ^-4 <y<1
It is a number that satisfies the condition ×10 ^-1 , and n/m is 1 ×
The condition 10 ^-3 <n/m<7×10 ^-1 is satisfied. ) and the like. However, the photostimulable phosphor used in the radiation image conversion panel of the present invention is not limited to the above-mentioned phosphor, and exhibits stimulated luminescence when irradiated with radiation and then irradiated with stimulated excitation light. Any fluorescent material may be used as long as it is a fluorescent material.

The average particle size of the stimulable phosphor used is appropriately selected within the range of 0.1 to 100 μm, taking into consideration the sensitivity and granularity of the radiation image conversion panel.
More preferably, those having an average particle size of 1 to 30 μm are used.

In the radiation image conversion panel of the present invention, the stimulable phosphor layer only needs to contain at least two types of stimulable phosphors whose stimulable luminescence efficiencies have different dependencies on stimulable excitation energy, and the stimulable phosphor layer of the present invention Examples of embodiments include a radiation image conversion panel having a layer structure as shown below.

(1) A radiation image conversion panel comprising a single photostimulable phosphor layer containing at least two types of photostimulable phosphors whose photostimulable luminous efficiencies differ in dependence on photostimulation excitation energy.

(2) The photostimulable phosphor layer consists of at least two layers,
A radiation image conversion panel in which at least two of the stimulable phosphor layers are composed of stimulable phosphors whose stimulable luminescence efficiencies are different in dependence on stimulable excitation energy.

FIG. 1 shows an example based on the embodiment of the present invention. In FIG. 1, numerals 1, 2, and 3 are photostimulable phosphors whose bright layer luminous efficiency depends on different photostimulable excitation energy, 12 is a mixture of the above photostimulable phosphors, and 4 is a mixture of the above-mentioned photostimulable phosphors.
5 is a protective film, and 5 is a support. 6 is a photostimulation excitation light blocking layer.

Note that the panel of the present invention is not limited to the above-mentioned examples, and for example, the support may or may not be provided as long as the structural strength of the photostimulable phosphor layer or the photostimulable light blocking layer is sufficient. good.

Further, in the case of an embodiment in which thermal stimulation excitation is performed, it is preferable to use heat-resistant materials for panel components such as a binder and a support.

Furthermore, when two types of stimulable phosphors with different stimulable excitation dependencies of stimulable luminescence efficiency are used, the ratio of their use varies depending on the purpose of use, but is 1:1 to 1:0.05.
(weight ratio) is preferable.

Generally, the photostimulable phosphor layer is prepared by dispersing the photostimulable phosphor in a suitable binder to prepare a coating solution.
It is produced by applying this to a uniform layer using conventional coating methods. Binders include, for example, proteins such as gelatin, polysaccharides such as dextran or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polymethyl methacrylate, vinyl chloride-vinyl acetate. copolymer,
Binders commonly used in layer construction are used, such as polyurethane, cellulose acetate butyrate, polyvinyl alcohol, silicone resins, polysiloxane resins, and the like. Generally, the binder is used in an amount of 0.01 to 1 part by weight per 1 part by weight of the stimulable phosphor. However, in terms of the sensitivity and sharpness of the radiation image conversion panel obtained, it is preferable to use less binder, and from the viewpoint of ease of application,
A range of 0.03 to 0.2 parts by weight is more preferred.

The thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention is determined by the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the binder and the stimulable phosphor. Although it varies depending on the mixing ratio etc., in general, when the stimulable phosphor layer consists of one layer, the thickness is 10 μm or more.
It is preferably selected from the range of 1200 μm, and more preferably selected from the range of 10 μm to 800 μm. In addition, when the photostimulable phosphor layer consists of two or more layers, the film thickness per layer is 10 μm to 800 μm.
The diameter is preferably selected from the range of 10 μm to 600 μm in order to reduce the deviation of radiation images obtained from each stimulable phosphor layer. In addition, for the purpose of improving the sharpness of the radiation image conversion panel of the present invention,
55-146447, white powder may be dispersed in the stimulable phosphor layer of the radiation image conversion panel; The stimulable phosphor layer of the image conversion panel may be colored with a coloring agent that absorbs stimulable excitation light.

In the radiation image conversion panel of the present invention, various polymeric materials, glass, etc. that are transparent to stimulated excitation light and stimulated luminescence are used as the support for supporting the photostimulable phosphor layer. In particular, materials that can be processed into flexible sheets or rolls are suitable for handling as information recording materials, and from this point of view, for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate. Plastic films such as films are particularly preferred. These supports may be provided with a subbing layer on the surface on which the photostimulable phosphor layer is provided, for the purpose of improving adhesion to the photostimulable phosphor layer. The film thickness of the support varies depending on the material of the support used, but is generally 80 μm to 1000 μm, more preferably 80 μm to 500 μm from the viewpoint of handling.

In the radiation image conversion panel of the present invention, the photostimulable phosphor layer is generally physically or chemically applied to the surface opposite to the surface on which the support for the photostimulable phosphor layer is provided. A protective layer is provided to protect the material. This protective layer may be formed by directly applying a protective layer coating solution onto the stimulable phosphor layer, or by adhering a separately formed protective layer onto the stimulable phosphor layer. It's okay. As the material for the protective layer, common protective film materials such as cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, and nylon are used. The thickness of these protective films is generally preferably about 1 μm to 40 μm.

The photostimulation excitation light blocking layer used as necessary in the radiation image conversion panel of the present invention can be made of any material as long as it reflects and/or absorbs the photostimulation excitation light. It is preferable that the panel be flexible in handling as an image conversion panel. From this point, for example, Al, Pb, Ni, Cu,
Metal sheets made of metals such as Zn, Ag, Pt, Au, Fe, etc. and their alloys, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film,
polyimide film, triacetate film,
Various sheet materials include plastic film sheets such as polycarbonate film, and paper. However, when a plastic film sheet or paper is used as a photostimulation excitation light blocking layer, these sheets themselves have almost no ability to block photostimulation excitation light, so the sheet may be used as a photostimulation reflection layer or absorption layer. It is necessary to color the sheet itself in order to make it look like this. In order for the sheet to become a photostimulation excitation light reflecting layer, the sheet may be colored with a white pigment or the like, and in order to make the sheet become a photostimulation excitation light absorption layer, the sheet may be colored in a photostimulation excitation light absorption layer. It may be colored with a pigment that absorbs light or a black pigment.

Instead of coloring the sheet itself, a stimulated excitation light reflecting layer or an absorbing layer may be provided on one or both sides of the sheet. As the stimulated excitation light reflection layer, a metal reflection layer may be provided on the surface of the sheet by a method such as vapor deposition or sputtering, or a white pigment layer or the like may be provided by a method such as coating. As the photostimulation excitation light absorption layer, a pigment or a black pigment that absorbs photostimulation excitation light may be provided on the surface of the sheet by a method such as coating.

Furthermore, after coloring the sheet as necessary, a photostimulation excitation light reflection layer or an absorption layer may be provided on the surface thereof, or a photostimulation excitation light reflection layer may be provided on one side of the sheet and a photostimulation excitation light reflection layer is provided on the other side. An excitation light absorption layer may also be provided.

In addition to the sheet-like material, the photostimulation light blocking layer may be made by dispersing white powder, black powder, etc. in a resin and applying the same.

The thickness of the stimulated excitation light blocking layer of the radiation image conversion panel of the present invention is preferably as thin as possible;
It is 1000 μm or less, more preferably 400 μm or less. If the thickness of the photostimulable excitation light blocking layer exceeds 1000 μm, the thickness of the radiation image conversion panel as a whole becomes large, making handling difficult. In addition, for the purpose of improving the adhesion to the photostimulable phosphor layer, a subbing layer may be provided on one or both sides of the photostimulable light blocking layer.

The radiation image conversion panel of the present invention is, for example, a second
An excellent radiographic image is obtained when the radiographic image conversion method schematically shown in the figure is used. That is, in FIG. 2, 10 is an imaging unit, and 20 is a first unit for reading a radiation image of the first photostimulable phosphor.
A reading section 30 indicates a second reading section for reading a radiation image of the second photostimulable phosphor.

In the imaging unit 10, the radiation emitted from the radiation source 101 toward the subject 102
2, the first photostimulable phosphor 105 and the second photostimulable phosphor layer 104 of the radiation image conversion panel 103 have different photostimulable excitation energy dependencies of stimulated luminescence efficiency. Stimulable fluorophore 1
06, and a radiation image of the subject is stored and recorded. Next, this radiation image conversion panel 103
is sent to the first reading section 20.

In the first reading section 20, the first photostimulable excitation light 202 from the reading light source 201 is one-dimensionally applied onto the photostimulable phosphor layer 104 of the radiation image conversion panel 103 by a light deflector such as a galvanometer mirror. By being deflected and sub-scanning the radiation image conversion panel 103, the entire surface of the stimulable phosphor layer 104 is irradiated with the stimulable excitation light 202. When the photostimulable excitation light 202 is irradiated in this way, the first photostimulable excitation light 202 that has a photostimulated excitation energy distribution that matches the first photostimulated excitation light 202 contained in the photostimulable phosphor layer 104 of the radiation image conversion panel 103 is emitted. The stimulable phosphor 105 of No. 1 emits stimulated luminescence that is proportional to the radiation energy stored and recorded therein. This emitted light passes through a filter 203 that cuts only the stimulated excitation light 202, and then enters a photoelectric converter 204 where it is photoelectrically converted. The output of photoelectric converter 204 is amplified by amplifier 205. The radiation image conversion panel 103 that has finished reading the first photostimulable phosphor 105 is sent to the second reading section 30.

In the second reading unit 30, in the same manner as in the first reading unit 20, the second photostimulable excitation light 302 from the reading light source 301 is used to direct the photostimulable excitation light 302 of the radiation image conversion panel 103 to the radiation image conversion panel 103 using an optical polarizer such as a carbano mirror. The photostimulable excitation light 302 is one-dimensionally deflected onto the light layer 104 and sub-scanned by the radiation image conversion panel 103, thereby irradiating the entire surface of the photostimulable phosphor layer 104. When the stimulable excitation light 302 is irradiated in this way, a stimulable excitation light 302 is irradiated with the stimulable phosphor layer 104 of the radiation image conversion panel 103. 2 photostimulable phosphor 1
06 emits stimulated luminescence that is proportional to the radiation energy stored and recorded therein, and this luminescence is caused by a filter 303 that cuts only the stimulated excitation light 302.
After passing through, the light enters a photoelectric converter 304, undergoes photoelectric conversion, and is amplified by an amplifier 305.

The final output 206 of the first reading unit 20 and the final output 306 of the second reading unit 30 may be output as visible images on a hard copy or CRT separately, or may be electrically superimposed or subtracted. The image may be processed and output as a single visible image on a hard copy or CRT.

Furthermore, the radiation information stored in the radiation image conversion panel 103 is grasped from the final output 206 of the first reading section 20, and based on this information, the sensitivity of the photoelectric converter 304 of the second reading section 30 and the sensitivity of the amplifier 305 are adjusted. The amplification factor etc. may also be set.

Stimulable fluorescent layer 1 of radiation image conversion panel 103
The first photostimulable phosphor 105 and the second photostimulable phosphor 105 contained in 04
The stimulable phosphors 106 need not be read in this order; they may be read in the reverse order or at the same time.

(Example) Next, the present invention will be explained by examples.

Example 1 BaFBr: 4 parts by weight of Eu photostimulable phosphor, BaSO ₄ :
4 parts by weight of Mn photostimulable phosphor and 1 part of silicone resin
parts by weight were mixed and dispersed using 5 parts by weight of a solvent (toluene) to prepare a coating solution for a photostimulable phosphor layer. Next, this coating solution was uniformly applied onto a polyimide amide resin as a support with a thickness of 200 μm placed horizontally, and air-dried to form a stimulable phosphor layer with a thickness of about 400 μm. A radiation image conversion panel A was created.

Using this radiation image conversion panel A
After simple radiography of the chest was performed using X-rays under the conditions of 100 KVp and 100 mA, two pieces of radiographic image data were obtained by reading with a device used in the radiographic image conversion method shown in FIG. In this embodiment, the first reading light source 201 is a 500mW CO ₂ laser (10600n
m), the reading light source 30 of the second reading section
1, a 50 mW He-Ne laser (633 nm) was used.

The two image data obtained were electrically superimposed and reconstructed as one image. The obtained images reproduced even the slightest differences in the contrast of the subject, and were of extremely high diagnostic value.

Example 2 In Example 1, 4 parts by weight of BaF _0.95 Br _1.05 :Eu photostimulable phosphor was used instead of BaFBr:Eu photostimulable phosphor, and 4 parts by weight of BaSO ₄ :Mn photostimulable phosphor was used instead of BaFBr:Eu photostimulable phosphor.
A radiation image conversion panel B of the present invention was prepared in the same manner as in Example 1 except that ZnS:Cu and 4 parts by weight of Pb stimulable phosphor were used.

Example 1 using this radiation image conversion panel B
The reading light source 201 of the first reading section is
A radiographic image was obtained in the same manner as in Example 1, except that a 50 mW Ar laser (515 nm) was used and the reading light source 301 of the second reading section was a 50 mW semiconductor laser (800 nm). The obtained images reproduced even the slightest contrast differences in the subject, and were of extremely high diagnostic value.

Example 3 A radiation image conversion panel of the present invention was produced in the same manner as in Example 1 except that BaFCl:Tb,Eu photostimulable phosphor was used instead of BaSO ₄ :Mn photostimulable phosphor in Example 1. Created C.

Using this radiation image conversion panel C, a radiation image was obtained in the same manner as in Example 1. The obtained images reproduced even the slightest contrast differences in the subject, and were of extremely high diagnostic value.

Comparative Example 1 A comparative radiation image conversion panel P was prepared in the same manner as in Example 1 except that BaFI:Eu photostimulable phosphor was used instead of BaSO ₄ :Mn photostimulable phosphor in Example 1. Created.

Using this comparative radiation image conversion panel P,
In the first embodiment, the reading light source 201 of the first reading section is a 50 mW He-Ne laser (633 nm), and the reading light source 301 of the second reading section is a 50 mW He-Ne laser (633 nm).
An attempt was made to obtain two radiographic image data in the same manner as in Example 1 except that the W Kr ⁺ laser (6471 nm) was used, but the second image data had a poor S/N ratio and could not be put to practical use. Nakatsuta.

Example 4 ZnS: 8 parts by weight of Cu, Pb photostimulable phosphor and 1 part by weight of polyvinyl butyral resin were mixed and dispersed using 5 parts by weight of a solvent (cyclohexanone), and applied for the photostimulable phosphor layer. The liquid was adjusted. Next, this coating solution was uniformly applied onto a horizontally placed transparent polyethylene terephthalate layer having a thickness of 300 μm and air-dried to form a first stimulable phosphor layer having a thickness of about 150 μm.
Similarly, 8 parts by weight of BaFBr:Eu photostimulable phosphor and 1 part by weight of polyvinyl butyral resin were mixed and dispersed using 5 parts by weight of a solvent (cyclohexanone) to form a coating solution for the photostimulable phosphor layer. A second photostimulable phosphor layer having a thickness of about 150 μm is formed by uniformly coating the first photostimulable phosphor layer and drying it naturally, thereby forming a radiation image D of the present invention. It was created.

Using this radiation image conversion panel D, in the first embodiment, the reading light source 201 of the first reading section
A 50 mW semiconductor laser (800 nm) was used to perform photostimulation excitation from the support side and photoelectric conversion was performed on the support side, and a 50 mW He-Ne laser (633 nm) was used as the reading light source 301 of the second reading section. A radiographic image was obtained in the same manner as in Example 1 except for the above. The obtained images reproduced even the slightest contrast differences in the subject, and were of extremely high diagnostic value.

Comparative Example 2 In Example 4, the support was made of black polyethylene terephthalate with a thickness of 300 μm, and the lower side of the support was coated with ZnS:Cu, Pb stimulable phosphor.
The first photostimulable phosphor layer is BaFBr:Eu on the upper side.
A comparative radiation image conversion panel Q was prepared in the same manner as in Example 4, except that a photostimulable phosphor was applied as a second photostimulable phosphor layer.

Using this comparative radiation image conversion panel Q,
50 in the first reading section in the same manner as in Example 4.
The first photostimulable phosphor layer is read with a mW semiconductor laser, and a 50 mW He-
The second photostimulable phosphor layer was read with a Ne laser to obtain two radiation image data.

The obtained two image data were electrically superimposed and reconstructed as one image, but there was a shift between the two images, and the reconstruction actually deteriorated the sharpness. did.

Example 5 In Example 1, BaFBr:Eu stimulable phosphor 6
A radiation image conversion panel E of the present invention was prepared in the same manner as in Example 1 except that parts by weight and 2 parts by weight of BaSO ₄ :Mn photostimulable phosphor were used in the same proportions.

Using this radiographic image conversion panel E, simple chest radiography was performed in the same manner as in Example 1, and then the two pieces of radiographic image data were read by a device used in the radiographic image conversion method shown in FIG. Obtained.

In this embodiment, the reading light source 2 of the first reading section
A thermal head is used instead of 01, and a 50mW reading light source 301 of the second reading section is used.
A He-Ne laser (633 nm) was used. Furthermore, in this embodiment, the radiation image information stored in the radiation image conversion panel E of the present invention is grasped from the radiation image data obtained by the first reading section, and the photoelectric converter and amplifier of the second reading section are After adjusting the gain, the image was read in the second reading section. The obtained images had optimal gain settings and were of high diagnostic value.

(Effects of the Invention) As explained above, according to the radiation image conversion method of the present invention, it is possible to obtain radiation image data of a plurality of sheets by one radiation irradiation.

Further, according to the radiation image exchange method of the present invention,
There is almost no image shift between multiple radiographic images, and it is possible to obtain high-quality radiographic images through overlapping processing or the like.

Furthermore, according to the radiation image conversion method of the present invention,
When obtaining radiation image data for a plurality of images, the reading conditions for the second and subsequent images can be controlled from the image information of the first image, making it possible to obtain high-quality radiation images.

The present invention has many effects as described above, and is industrially very useful.

[Brief explanation of the drawing]

FIG. 1 is an example of the radiation image conversion panel of the present invention, and FIG. 2 is a schematic explanatory diagram of a radiation image conversion method using the radiation image conversion panel of the present invention. 10... Imaging department, 101... Radiation source, 102
...Subject, 103...Radiation image conversion panel,
104... Stimulable phosphor layer, 105... First photostimulable phosphor, 106... Second photostimulable phosphor, 1
07...Support, 20...First reading section, 20
1... Stimulation excitation light source, 202... Stimulation excitation light, 2
03... Filter, 204... Photoelectric converter, 2
05...Amplifier, 206...Output, 30...Second
Reading section, 301... Stimulative excitation light source, 302...
...Photostimulation excitation light, 303...Filter, 304...
...Photoelectric converter, 305...Amplifier, 306...Output.

Claims (1)

[Scope of Claims] 1. A radiation image conversion panel having a stimulable phosphor layer containing at least two types of stimulable phosphors having different stimulable excitation energy dependencies of stimulable luminescence efficiency, A radiation image conversion method characterized in that a plurality of radiation images are read out as separate images by exciting the stimulable phosphor with different stimulable excitation energy corresponding to the stimulable phosphor. 2. The radiation image conversion method according to claim 1, wherein at least one type of the stimulable phosphor is a thermally stimulable phosphor.