JP2004163410A - Stimulable phosphor screen showing less scattering upon stimulation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stimulatable phosphor screen or panel which is useful for an X-ray recording system that has an excellent compromise between the speed of the recording system (or the minimum patient dose) and images with high sharpness and low noises. <P>SOLUTION: In the stimulatable phosphor screen or panel including a support 3, a layer 2 made of lead or containing a lead compound and a storage phosphor layer 1, the layer 2 containing lead or the lead compound exists as an intermediate layer between the support 3 and the storage phosphor layer 1. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to a method for storing and reproducing a radiation image using a radiation image storage sheet or panel, and radiation having a stimulable phosphor layer suitable for use in the method for storing and reproducing a radiation image. Image storage screen or panel and layer arrangement.

BACKGROUND OF THE INVENTION As an alternative to conventional radiography, radiographic image recording and reproduction methods utilizing image storage screens or panels known to include sheets or layers containing stimulable phosphors have been proposed. The method comprises causing the stimulable phosphor of the storage panel to absorb radiation energy that has passed through or emitted from the subject, and then excites the stimulable phosphor with electromagnetic waves such as visible or infrared (ie, stimulating light); Emits radiation energy stored in the phosphor as light emission (ie, stimulated emission), photoelectrically detects the emitted light to obtain an electrical signal, and from the electrical signal the radiation of the subject as a visible image. And reproducing the image. In order to use the panel repeatedly, the radiation energy remaining there is further erased and then further subjected to the procedure of storing and reconstructing the next image.

  US-A 3,585,527 discloses a method for producing an X-ray image with a photostimulable phosphor contained in a panel. The panel is exposed to an incident X-ray beam modulated according to the pattern, so that the phosphor temporarily stores the energy contained in the X-ray radiation pattern.

  At some interval after exposure, a beam of visible or infrared light scans the panel and stimulates the emission of stored energy as light. The light is detected and sequentially converted to an electrical signal, which is processed to produce a visible image. For this purpose, the phosphor should store as much as possible of the incident X-ray energy and emit as little as possible of the stored energy until stimulated by the scanning beam. This is referred to as "digital radiography" or "computer radiography".

  Image quality is extremely important in applications for digital radiography. High resolution and low noise levels are highly desirable. Resolution (sharpness) is determined to a large extent by the scattering properties of the phosphor layer. As a result, the phosphor layer thickness is limited by the desired sharpness. Especially in mammography applications, the sharpness should be very high to have an image with a sufficiently high diagnostic value, without leaving doubt about the presence or absence of microcalcifications, in order to avoid further retakes. Therefore the phosphor layer thickness should not exceed 150 μm to obtain the desired sharpness or resolution. However, it has been established that in practice the resolution does not reach the expected level, and that every measure has been taken to reach it, an unexpectedly low level is achieved.

  The image quality produced by any radiographic system that uses a phosphor screen, and thus by a digital radiographic system, is highly dependent on the construction or layer arrangement of the phosphor screen. In general, the thinner the phosphor screen at a given amount of x-ray absorption, the better the image quality. This means that the lower the ratio of binder to phosphor of a phosphor screen, the better the image quality that can be achieved with that screen. Optimum sharpness can be obtained when a binderless screen is used. Such screens can be produced, for example, by physical vapor deposition, which may be thermal vapor deposition of a phosphor material on a support, sputtering, electron beam vapor deposition, and the like. However, this manufacturing method can be used to manufacture high quality screens with any available phosphor. The above manufacturing method leads to the best results when phosphor crystals with high crystal symmetry and simple chemical composition are used.

  The use of alkali metal halide phosphors in storage screens or panels is well known in the field of storage phosphor radiation, and the high crystal symmetry of these phosphors provides a structured screen and a binderless screen simultaneously. can do.

  It has been disclosed that when binderless screens with alkali halide phosphors are produced, it is beneficial to deposit the phosphor crystals in several types, such as piles, needles, tiles, etc. I have. U.S. Pat. No. 4,769,549 discloses that the image quality of a binderless phosphor screen can be improved when the phosphor layer has a block structure formed by narrow columns. U.S. Pat. No. 5,055,681 discloses a storage phosphor screen containing an alkali halide phosphor in a pile-like structure. The image quality of such screens still needs to be improved, and JP-A 06/230198 discloses that the surface of a screen having columnar phosphors is rough and that the height of the surface can improve its sharpness. . US-A 5,874,744 focuses on the reflectivity of phosphors used to produce storage phosphor screens having needle-like or columnar phosphors.

EP-A 111 113 458 discloses binderless storage phosphor screens comprising alkali metal storage phosphors, wherein said screen has an intensity I ₁₀₀ (100) diffraction such that I ₁₀₀ / I ₁₁₀ ≧ 1. XRD spectrum with (110) diffraction lines having a line and intensity I ₁₁₀ is characterized. Such a phosphor screen shows a better compromise between speed and sharpness.

  All screens disclosed in this prior art are capable of producing X-ray images with good quality, but with a higher speed between the recording system (i.e., the lowest possible patient dose) and images with higher sharpness and lower noise. There is still a need for a good compromise.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to provide an X-ray recording system that has a good compromise between the speed of the recording system (i.e., the lowest possible patient dose) and images with high sharpness and low noise as normally expected. It is to provide a useful stimulable phosphor screen.

  The above objective is accomplished by providing a stimulable phosphor screen having the special features defined in claim 1. Specific features for preferred embodiments of the invention are disclosed in the dependent claims.

  Further advantages and embodiments of the present invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows lead as an interlayer between a phosphor layer coated with a stimulable phosphor (BaFBr: Eu, CsBr: Eu) and a support (PET, Al, glass, amorphous carbon). 3 shows a storage phosphor panel with foil.

  FIG. 2 shows a panel with a layer of lead glass between a conventional phosphor layer (with CsI: Eu as a conventional phosphor) and an electron detector (CCD, diode array).

DETAILED DESCRIPTION OF THE INVENTION Not only is the sharpness determined by the scattered radiation passing through the phosphor layer and dependent on the thickness and content of that layer, but also once the support layer or undercoat layer (which are the same Have also been unexpectedly found to be determined to a greater extent by the scattering of the radiation passing through and impacting.

  In the storage phosphor layer, the scattering properties are usually related to radiation in the wavelength range of the visible stimulating light, but the support or undercoat layer causes X-ray scattering and the support or undercoat layer is "backscattering". Development, also known as "".

  Said "backscatter" is generated in all layers known as the support layer or undercoat layer, said undercoat layer being between the support layer and the phosphor layer as an intermediate layer.

  With these ideas in mind, and further knowledge that the undercoat layer or support does not strongly absorb X-rays, X-rays penetrate to significant depths into the layers below the phosphor layer, and It is clear that "backscatter" appears in all layers farther from the radiation source than the phosphor layer. That is, "backscattering" induces "exposure of one or more pixels" and places a burden on the expected sharpness as actually achieved. It has been found that a sharpness loss results.

  In order to eliminate the above "backscattering loss factor", the following solution is found.

In one example according to the invention, a thin interlayer of a material that strongly absorbs X-rays, said material layer being between the phosphor layer and the underlying support layer, provides substantially improved sharpness. Is established. This result can be interpreted as being due to such a small distance that "backscattering" disappears to give rise to "neighboring pixels". Lead or a lead compound is particularly preferred as the strongly absorbing material for the intermediate layer.

  In another example according to the invention, it has been established that it is sufficient to have a material in the above-mentioned intermediate layer, wherein said material may absorb X-rays to a low extent, but it nevertheless does not scatter. Avoid to a large extent. As a result, the presence of less scattered light is not related to the actual "depth" at which scattered radiation is generated. This is because only one pixel is overlapped by the "scattering".

It is also known from lead as a preferred metallic material that, from the point of view mentioned in the second example, the amount of "backscattered radiation" generated in the lead layer is much lower than, for example, an aluminum or tungsten layer. A preferred alternative for supporting the preferred lead metal is amorphous carbon (a-C), which, to a large extent, generates very little backscatter, not only due to the particles absorbing the black radiation. Thanks.

  As a result, the presence of a thin interlayer containing lead or a lead compound supported by amorphous carbon is highly recommended. It is known that a "thick" layer, foil or screen of lead may be present in the cassette in which the phosphor plate is used, but said foil or screen is at a distance from the phosphor layer and the phosphor layer It is known to be located not as a coating layer between the phosphor layer and the support layer. Including an amorphous carbon film as a support further reduces the binder on the support having low X-ray absorption and low "backscatter" even if the storage phosphor layer is applied by vacuum deposition at a significantly higher temperature. It has been found that indeed opens up the prospects for producing a storage phosphor screen free of defects. Amorphous carbon film supports suitable for use in the present invention are commercially available through, for example, Tokyo Carbon Co, Ltd., Tokyo, Japan or Nissinbo Industries, Inc., Tokyo, Japan, where they are " Also referred to as "glassy carbon film" or "glassy carbon". Amorphous carbon is preferably applied in the manufacture of binderless phosphor screens by chemical vapor deposition in vacuum. This is because the support on which the phosphor is deposited can be heated to a temperature of about 400 ° C., thus requiring the use of a thermally stable support. Thus, even with supports containing only elements with a low atomic number, polymeric supports are not the most preferred, in contrast to the preferred amorphous carbon supports.

  In a phosphor panel or screen according to the invention, the thickness of the amorphous carbon layer can range from 100 μm to 3000 μm, but a thickness of 500 μm to 2000 μm is a compromise between flexibility, strength and X-ray absorption. Is preferred. EP Application No. 08/28/2002, provided with lead foil as an intermediate layer between the aC layer support and the phosphor layer. Phosphor screens or panels as described in 02100764 are highly preferred within the scope of the present invention.

  In another method, EP application no. It is advantageous to provide a stimulable phosphor screen having a support, characterized in that the support has a reflectivity of 80% or more as disclosed in U.S. Pat. No. 2,100,763 (filed on Jun. 28, 2002). . Preferably, said reflectivity is provided by an aluminum layer covering the support as disclosed therein. US-A 4,618,778 also discloses the addition of a reflective layer between the support and the layer containing the phosphor dispersed in a binder as applied here in a special example of the invention.

  In US-A 4,796,549 and US-A 496,375, which disclose a storage phosphor screen with a deposited phosphor layer without binder, in such screens a compromise between speed and sharpness is very favorable, sharpness and speed. It has been suggested that it is not required to include any special measures to further improve the compromise between the applications described in EP Application No. From the teaching of 01000697, even with a binderless stimulable phosphor screen with deposited phosphor, which already exhibits a high speed combined with a high sharpness, the screen layer arrangement can be up to 30% or more. It is recognized that a better speed / sharpness compromise can be achieved when including a support that is covered with a layer that absorbs the stimulating light and reflects at least 60% of the stimulated light. The demand optimizes the balance between the reflection and absorption characteristics of the system: while giving priority to high speeds, one would strive for 80% reflectivity (eg, as in mammography systems). When considering higher sharpness, the reflectivity should be lower and an absorption of less than 80% would be required.

  According to the invention, the lead-containing layer covering the support absorbs at least 80% of the stimulating light (for mammography applications) and reflects at least 80% of the stimulated light (generally applied radiography). In a particular example, said layer is covered with an adjacent thin layer, for example aluminum or another reflective layer, to achieve the above-mentioned values. Since the lead layer has reflective properties, it can be used in this way to further optimize the layer arrangement in the storage phosphor panel and to obtain an optimized resolution. Alternatively, for reflective properties, a lead foil in combination with a thin reflective aluminum foil can be used.

  As is known in the art of producing storage screens in which the storage phosphor is dispersed in a binder, the coloring of the screen is advantageously applied to enhance sharpness. For example, US-A 4,394,581 and US-A 4,491,736 disclose such screens. However, in the present invention, the support may be colored, but any advantageous effect on the colored layer due to the presence of a layer of lead as an intermediate layer between the support and the phosphor layer is obtained from the colored support. It is understood that it should be expected from the colored phosphor layer rather than from.

  Obviously, the storage phosphor panel is not limited to "storage phosphors without binder". “Evaporated phosphor” is further referred to throughout this specification as a phosphor produced by any method selected from the group consisting of thermal evaporation, chemical vapor deposition, electron beam evaporation, radio frequency evaporation, and pulsed laser evaporation. Means This deposition is preferably carried out under the conditions as described in EP-A-111458.

  A conventional phosphor such as a conventional CsI: Eu phosphor as in FIG. 2 may be used, and in a special case the panel is a conventional phosphor layer (1 ′) having CsI: Eu as the conventional phosphor. ) And the layer (2 ') of lead glass between the electron detectors (CCD, diode array) as layer (3') shows a panel according to the invention. Apart from the said conventional phosphors, well-known storage phosphors, such as for example BaFBr type phosphors known from US-A 5,514,298, are advantageously applied to panels as described in FIG. Is lead as an interlayer between the support (3) (PET, Al, glass, amorphous carbon) and the phosphor layer (1), coated with a stimulable phosphor (BaFBr: Eu, CsBr: Eu). Fig. 3 shows a storage phosphor panel having a foil, wherein a lead foil (2) is located as an intermediate layer between the phosphor layer (1) and the support (3).

  Preferred supports for the storage phosphor screen of the present invention are selected from the group consisting of ceramics, glass, polymer films, and amorphous carbon as described above. In the screen according to the present invention, among the polymer films, a heat-stable polyester film (for example, polyethylene terephthalate and polyethylene naphthalate) having a thickness of 100 to 1000 μm is preferred as a support. In order to achieve the desired absorption and reflection properties, the support used in the screen of the invention, apart from the desired lead-containing layer as a special layer, is deposited on the support in the case of needle-like phosphor deposition. Furthermore, there is no special layer to be coated. When the support for use in the storage phosphor screen of the present invention is glass, by heating at a temperature high enough to melt the glass particles or fibers together in a manner sufficient to form a plate. Preference is given to using fritted glass. The surface of such plates of fritted glass is uneven, and the profile depends on the diameter of the glass beads used to form the fritted glass plate. The lead-containing layer may further describe non-uniformities in the support for depositing the phosphor. This is a highly desirable example. Because it helps to deposit the phosphor crystals in needle-like form if desired.

  In a further example, a flexible layer of a lead or lead acid compound is provided with an adhesive layer on a flexible polymer support, and the lead or lead oxide dispersed in a binder coated on the adhesive layer. Layer. These lead or lead oxide layers have the special advantage that they do not absorb moisture and the flexible lead or lead acid compound layer coated on the polymer support is reduced due to the creation of an electrostatic charge during use. Having a defined propeneness.

  A lacquer layer may be provided as a barrier layer present on one or both sides of the intermediate lead foil or layer present on the support of the screen or panel of the present invention, where a thin and tough for lead foil screen is provided. Any of the well-known lacquers may be used to provide a transparent overcoat, on which the acicular stimulable phosphor may be deposited. The lacquer may be applied as a liquid by any conventional method and may be dried to form a tough, smooth overcoat finish on it. Further, a fluorine surfactant may be applied on the lacquer layer.

  The adhesive-coated polyethylene terephthalate film support to which the lead foil is applied is advantageously laminated to this support and dried to ensure good adhesion thereto. As another layer on top of the lead foil layer, a lacquer layer containing, for example, a polymeric polyvinyl chloride may be coated on this adhesive layer and dried. A thin layer of fluorosurfactant may then be applied over the lacquer layer and the structure may be completely dried. Thus, a flexible lead layer is provided as a support for the stimulable phosphor screen layer of the screen or panel according to the invention.

  It has been surprisingly found that the use of lead or lead oxide on a support layer as described above produces such improved results in conjunction with image sharpness due to reduced incident X-ray scattering. Further, the storage screens or panels of the present invention do not burden the applied system with respect to moisture and curl and other undesirable side effects (eg, static charge). Screens that are not susceptible to moisture absorption and that have antistatic properties provide better resolution or sharpness.

  Lead foil or lead oxide dispersed in a binder is commercially available. Various thicknesses of lead foil can be applied, but lead foils having a thickness of 25 μm to 150 μm are preferred. The thickness selected ultimately depends strongly on the application considered and the energy of the incident X-rays associated therewith.

  The lead foil layer may contain small amounts of other metals such as Sn and Sb in addition to Pb. This lead foil is then applied to a film support using the usual adhesives therefor. As a commercially available adhesive, for example UK2600 sold by BASF, Dusseldorf, Germany and mixed with Zappon® blue may be used. Other adhesives can be used as long as they are compatible with the lead layer and do not interfere with the recording of the X-ray image. After application of a suitable layer of adhesive to the film support, a lead foil layer is then laminated to it.

  Lead oxide dispersed in a suitable binder and coated with a layer on a preferred polymer support may be used as an alternative for lead foil. Any of the conventional binders such as those used for the dispersion of phosphors in the layers of an intensifying screen may be used here. Examples of such a binder include polyvinyl butyral, polyvinyl acetate, urethane, polyvinyl alcohol, polyester resin, and polymethyl methacrylate. According to the present invention, in a storage phosphor screen or panel, the binder containing a lead compound is selected from the group consisting of polyvinyl butyral, polyvinyl acetate, urethane, polyvinyl alcohol, polyester resin and polymethyl methacrylate. Usually, the binder is mixed with a suitable solvent and a conventional wetting agent as a dispersing aid for the lead oxide therein. The level of binder present should be kept low relative to the dispersed lead oxide to provide a thin support coated with lead.

  In one example, a support provided with an elastomeric layer on top and having a metal-containing filler therein may be used.

  Apart from the polymer support, the aluminum layer may be used coated with a layer of a poly (vinylidene-fluoride-hexafluoro-propylene) copolymer having a dispersed metal-containing filler such as lead oxide.

  Lead salts may be used as an alternative for lead oxide, said salts being from the group consisting of lead carbonate, lead acetate, lead iodide, lead chloride, lead fluoride, lead sulfide, lead sulfate and lead nitrate. Selected.

  To provide an embossed layer, a lead-based paint may be used and applied by well-known coating techniques (eg silk screen printing), and a needle-shaped phosphor deposited on that layer. Good.

  Substrates, such as glazings or polymeric supports, all of which are preferably cleaned, may alternatively be subjected to magnetic sputtering from a series of target cathodes, and the amount of each sputter-coated material May be controlled by changing the number of cathodes through which the support is passed during the coating operation. A layer of lead oxide may be deposited directly on a glass surface or a polymer support from a lead cathode operating in an oxygen-argon atmosphere. In certain applications associated with mammography, where soft x-ray exposure occurs, the lead oxide layer may be deposited to a thickness of about 50 angstroms. Obviously, for all other energy-rich exposures, a higher absorption layer thickness is preferred.

Details on magnetic sputtering can be found, for example, in the following documents:

  Sol-gel reactions have recently been used to make inorganic-organic composites. This general reaction, using hydrolysis and polycondensation of the metal alkoxide species, is preferably applied to provide a layer with lead oxide in the screen or panel layer arrangement of the present invention. According to the invention, in a particular example, the binder containing a lead compound in the storage screen or panel of the invention is a matrix of a polycondensation compound of the metal alkoxide species. The reaction takes place under the influence of a suitable catalyst, for example an acid, and a network is formed in the process. According to a further preferred embodiment of the present invention, the binder containing a lead compound is a matrix of an inorganic network of an alkoxymetal-substituted organic polymer or copolymer matrix.

  During the formation of this inorganic network, the alkoxy metal-substituted organic polymer or copolymer is also present in the reaction medium, undergoes the same polycondensation reaction as the hydrolyzed metal alkoxide, and is incorporated into the network. In a further example according to the present invention, the binder containing a lead compound is a matrix of an inorganic network of an alkoxy metal substituted organic polymer or copolymer matrix.

Certain types of inorganic-organic composites are named ORMOCHERS (ORganically Modified Ceramics), ORMOSILS (ORganically Modified Silicates) or CERAMERS. Scientific literature on inorganic-organic composites includes:

  In one example, the screen or panel according to the invention is provided with an intermediate layer, wherein said lead compound is an oxide or hydroxide of lead metal dispersed in a binder. In a preferred embodiment, the phosphor screen or panel according to the invention comprises a crosslinked polymer matrix and a binder containing a lead compound in a layer comprising a colloid of silica, said matrix comprising dialkoxysilane, trialkoxysilane, tetraalkoxysilane, titanate. , Zirconates and aluminates, wherein the matrix comprises a colloid of a lead metal oxide or hydroxide. Alternatively, the support may be coated with a hydrophilic layer comprising a crosslinked polymer matrix and a colloid of silica, said matrix being selected from the group consisting of dialkoxysilanes, trialkoxysilanes, tetraalkoxysilanes, titanates, zirconates and aluminates. Derived from a crosslinker, the matrix comprises a colloid of an oxide or hydroxide of lead metal. The amount of silica in the layer is preferably in the range of 1 to 50 times the amount of the crosslinking agent. Crosslinked polymer matrices include N-trimethoxy-N, N, N-trimethylammonium chloride, 3-aminopropyltriethoxysilane; a mixture of dimethyldimethoxysilane and methylmethoxysilane sold as Z-6070 by Dow Corning Company; Sidoxypropyltrimethoxysilane can be used, but is not limited to these.

  The binder-free phosphor screens according to the invention are obtained by vacuum deposition of phosphor crystals on a support as well as mixing the components for the phosphor (phosphor precursor), and then evaporating this mixture in situ during evaporation. It can be made by forming a phosphor.

  It is further preferred according to the present invention to provide a binderless stimulable phosphor screen on a polymer film covered with a lead layer as a support in the intermediate layer, said intermediate layer for forming a fine uneven pattern. It has an embossed surface. The phosphor in the binderless phosphor screen according to the present invention can be any conventionally known stimulable phosphor. Preferably, the storage phosphor used in the binderless phosphor screen is a binderless phosphor having acicular crystals, and in an even more preferred embodiment said acicular phosphor crystals are alkali metal phosphor crystals. is there.

Highly suitable phosphors are, for example, phosphors according to formula I below:
M ¹⁺ X. aM ²⁺ X ′ ₂ bM ³⁺ X ″ ₃ : cZ (I)
^Wherein M ¹⁺ is at least one element selected from the group consisting of Li, Na, K, Cs and Rb, and M ²⁺ is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, Pb and At least one element selected from the group consisting of Ni, wherein M ³⁺ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Z is at least one element selected from the group consisting of Lu, Al, Bi, In and Ga, and Z is at least one element selected from the group consisting of Ga ¹⁺ , Ge ²⁺ , Sn ²⁺ , Sb ³⁺ and As ^3+. X, X ′ and X ″ may be the same or different and each represents a halogen atom selected from the group consisting of F, Br, Cl and I, and 0 ≦ a ≦ 1, 0 ≦ b ≦ 1 and 0 <c ≦ 0. It. Such phosphors have been disclosed in US-A 5736069, for example.

A particularly preferred phosphor for use in the binderless phosphor screen of the present invention is a CsX: Eu stimulable phosphor, wherein X represents a halide selected from the group consisting of Br and Cl, wherein the phosphor is Is produced by a method comprising the following steps:
- EuX _{'2, EuX' 3} and EuOX '(where, X' is F, Cl, an element of one selected from the group consisting of Br and I) ¹⁰ of europium compound selected from the group consisting of ^-3 Mixing the CsX with ~ 5 mol%;
Burning the mixture at a temperature of 450 ° C. or higher;
-Cooling the mixture; and-recovering the CsX: Eu phosphor.

Most preferably, a CsBr: Eu stimulable phosphor is used, said phosphor being made by a method comprising the following steps:
- EuX _{'2, EuX' 3} and EuOX '(where, X' is F, Cl, an element of one selected from the group consisting of Br and I) ¹⁰ of europium compound selected from the group consisting of ^-3 Mixing the CsX with ~ 5 mol%;
Burning the mixture at a temperature of 450 ° C. or higher;
-Cooling the mixture; and-recovering the CsX: Eu phosphor.

  A binderless screen is made by bringing the finished phosphor onto a support by any method selected from the group consisting of thermal evaporation, chemical vapor deposition, electron beam evaporation, radio frequency evaporation and pulsed laser evaporation. be able to. It is also possible to bring the alkali metal halide and dopant together and co-evaporate them on a support in such a way that the alkali metal phosphor is doped during the manufacture of the screen.

The present invention is a method for producing a phosphor screen containing a CsX: Eu stimulable phosphor, wherein X represents a halide selected from the group consisting of Br and Cl, further comprising a method comprising the following steps: Include:
- EuX _{'2, EuX' 3} and EuOX '(where, X' is F, Cl, a is selected halides from the group consisting of Br and I) Europium compound selected from the group consisting of and the number of CsX To a state of vapor deposition; and-doped with 10 ^{-3 to 5} mol% of europium by a method selected from the group consisting of thermal vapor deposition, chemical vapor deposition, electron beam vapor deposition, radio frequency vapor deposition and pulsed laser vapor deposition. Both the CsX and the europium compound are deposited on the support in such a ratio that the resulting CsX phosphor is formed on the support.

The deposition can be performed from a single vessel containing the mixture of the starting compounds in the desired proportions. The method is a method of manufacturing a phosphor screen containing a CsX: Eu stimulable phosphor (where X represents a halide selected from the group consisting of Br and Cl), further comprising a method comprising: Include:
- EuX _{'2, EuX' 3} and EuOX '(where, X' is F, Cl, a is selected halides from the group consisting of Br and I) ^{10 -3} ~ europium compound selected from the group consisting of Mixing 5 mol% with the CsX;
-Bringing the mixture into a state of vapor deposition; and-depositing the mixture on a support by a method selected from the group consisting of physical vapor deposition, thermal vapor deposition, chemical vapor deposition, electron beam vapor deposition, radio frequency vapor deposition and pulsed laser vapor deposition. I do.

  Apart from applications in "needle-shaped phosphors", especially those using columnar CsBr: Eu needle-shaped crystals, screens or panels coated with "powdered phosphor" are particularly considered in general radiographic diagnostics. Can be In particular, for applications in mammography, for the reasons mentioned above, the phosphor layer should be very thin (on the order of 150 μm) so that X-rays can easily pass through the phosphor layer, so that in the layer below the phosphor layer Generates much more backscattered radiation.

  Aside from its use in digital radiography, such applications may also be considered "direct radiography", in which the electronic detector makes direct contact with the direct processing of the signal obtained as already shown in FIG. provide. It will be appreciated that in a similar manner sharpness is not only determined by the thickness of the phosphor layer for such direct radiographic systems, but also by the scattering characteristics of the diode array under the CCD. An additional condition is the presence of a transparent foil, which cannot form a problem if, for example, lead glass is used: its thin layer between the phosphor layer and the electron detector (layer (2 'in FIG. 2)) Application) will improve sharpness to a significant degree.

The present invention further includes a method of manufacturing a storage phosphor panel comprising the following steps:
Providing a suitable support (eg an amorphous carbon film) covered with an intermediate lead-containing sheet or foil as a support material for a phosphor plate or panel;
-Vacuum depositing a storage phosphor layer on said support material;
-Optionally laminating a polymer film on the side of the support material which is not covered by said phosphor.

The present invention further includes a method of manufacturing a storage phosphor panel comprising the following steps:
Providing a suitable support (eg an amorphous carbon film) covered with an intermediate lead-containing sheet or foil as a support material for a phosphor plate or panel;
-Applying a specular reflection layer thereon;
-Further depositing a storage phosphor layer on said reflective layer; and-optionally laminating a polymer film on the side of the reflective layer not covered by said phosphor.

The present invention further includes a method of manufacturing a storage phosphor panel comprising the following steps:
Providing a suitable support (eg an amorphous carbon film) covered with an intermediate lead-containing sheet or foil as a support material for a phosphor plate or panel;
-Applying a specular reflection layer thereon;
Chemical vapor deposition of a moisture repellent layer (preferably a parylene layer) on said specular layer;
-Further vacuum depositing a storage phosphor layer on said reflective layer and optionally polishing said phosphor layer; and-optionally further depositing a polymer film on the side of the amorphous carbon film not covered by said phosphor. Laminate.

  The screen or panel of the present invention may include any known protective layer on the phosphor layer. However, particularly preferred for use are EP Application No. 02100297 (filed on March 26, 2002); 01000694 and 01000695 (both filed on December 3, 2001). In order to provide an image storage panel with high surface durability, i.e. to avoid surface damage due to abrasion and dirt after multiple uses, further ease of handling, excellent image quality without screen structure noise (improved Advantageously, the radiation image storage panel comprises a protective coating, said protective coating having, in addition to a binder, a white color having a reflectance of 1.6 or more, more preferably 2.0 or more. The protective coating is characterized in that it comprises a pigment and, more particularly, titanium dioxide present in the binder, and optionally further comprises a urethane acrylate, the protective coating being characterized in EP application no. It has a surface roughness (Rz) of 2 μm to 10 μm as disclosed in 01000711 (filed on Dec. 5, 2001).

Alternatively, the protective layer is a vinyl resin containing a portion derived from an ester of acrylic acid and a vinyl resin containing a portion derived from an ester of methacrylic acid, more preferably EP Application No. No. 02100235 (filed on Mar. 8, 2002), comprising a polymer compound selected from the group consisting of thermoplastic rubbers. For sharpness, the polymer further comprises at least one colorant, more preferably a colorant having the same absorption properties for stimulating rays as colorants deposited by chemical vapor deposition as described above. As the outermost layer, for example, EP Application No. A parylene layer is highly preferred as a moisture-resistant layer, as described in 0104001.8 (filed August 23, 2001). In still another example according to the present invention, poly (p-xylylene) (= parylene), poly (p-2-chloroxylylene), poly (p-2,6-dichloroxylylene), fluorine-substituted poly (p- xylylene), photostimulable binderless phosphor screen that is overcoated with MgF _2, or a combination thereof are provided. Said technique is advantageously applied in this case, as chemical vapor deposition is a technique that can be applied when using those components. "Parylene" provides especially excellent moisture resistance, whereas MgF ₂ provides excellent antireflection properties.

  The screens or panels according to the invention can also have reinforcing edges, for example as described in US-A 5,334,842 and US-A 5,340,661.

  The surface of the phosphor layer (1) in the panel or screen of the present invention can be smaller than the surface of the support (2) so that the phosphor layer does not reach the edge of the support. Such screens are described, for example, in EP Application No. No. 02100297 (filed on March 26, 2002).

The invention further includes a method for exposing a subject to X-rays comprising the following steps:
An X-ray tube equipped to emit X-rays having an energy of 70 keV or less, and a photometer coupled to the X-ray tube for switching the tube on and off according to the X-ray dose reaching the photometer Providing an X-ray device comprising:
-Placing a subject between the X-ray tube and the photometer;
-Placing a binderless storage phosphor panel or screen according to the invention between the object and the photometer; and-the object, the cassette and the photometer until the photometer switches off the X-ray tube. Activate the X-ray tube to expose.

  Although the preferred examples have been described in detail, it is clear that the invention should not be limited to those examples.

A storage phosphor panel having a lead foil as an intermediate layer between a phosphor layer coated with a stimulable phosphor (BaFBr: Eu, CsBr: Eu) and a support (PET, Al, glass, amorphous carbon). Show. Figure 2 shows a panel with a layer of lead glass between a conventional phosphor layer (with CsI: Eu as a conventional phosphor) and an electron detector (CCD, diode array).

Claims (11)

  A stimulable phosphor screen or panel comprising a phosphor layer and a support, wherein an intermediate layer comprising lead or a layer comprising a lead compound is present between said support and said phosphor layer. Or panel.   The phosphor screen or panel according to claim 1, wherein the lead compound is an oxide or hydroxide of lead metal dispersed in a binder.   The phosphor screen or panel according to claim 2, wherein said binder containing a lead compound is selected from the group consisting of polyvinyl butyral, polyvinyl acetate, urethane, polyvinyl alcohol, polyester resin and polymethyl methacrylate.   3. The phosphor screen or panel according to claim 2, wherein said binder containing a lead compound is a matrix of a polycondensation compound of a metal alkoxide species.   5. The phosphor screen or panel according to claim 4, wherein said binder containing a lead compound is a matrix of an inorganic network of an alkoxy metal substituted organic polymer or copolymer matrix.   A layer comprising a colloid of silica and a crosslinked polymer matrix wherein the binder containing a lead compound is derived from a crosslinker selected from the group consisting of dialkoxysilane, trialkoxysilane, tetraalkoxysilane, titanate, zirconate and aluminate 6. The phosphor screen or panel of claim 5, wherein the matrix comprises a colloid of a lead metal oxide or hydroxide.   7. The phosphor screen or panel according to claim 1, wherein said support is selected from the group consisting of ceramics, glass, amorphous carbon and polymer films.   8. The phosphor screen or panel according to claim 1, wherein the intermediate layer has a surface subjected to embossing for forming a fine uneven pattern.   9. A phosphor screen or panel according to any of the preceding claims, wherein the phosphor is a binderless phosphor having needle-like crystals.   10. The phosphor screen or panel according to claim 9, wherein said acicular phosphor crystals are alkali metal phosphor crystals. The phosphor screen or panel according to claim 10, wherein the alkali metal phosphor is a CsX: Eu stimulable phosphor, wherein X represents a halide selected from the group consisting of Br and Cl. A phosphor screen or panel wherein said phosphor is produced by a method comprising the following steps:
- EuX _{'2, EuX' 3} and EuOX '(where, X' is F, Cl, an element of one selected from the group consisting of Br and I) ¹⁰ of europium compound selected from the group consisting of ^-3 Mixing the CsX with an amount of ５5 mol%;
Burning the mixture at a temperature of 450 ° C. or higher;
Cooling the mixture; and recovering the CsX: Eu phosphor.

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