WO1991011011A1 - Solid-state structure for intensifying the effect of x-ray radiation, particularly for industrial applications - Google Patents

Solid-state structure for intensifying the effect of x-ray radiation, particularly for industrial applications Download PDF

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Publication number
WO1991011011A1
WO1991011011A1 PCT/HU1990/000008 HU9000008W WO9111011A1 WO 1991011011 A1 WO1991011011 A1 WO 1991011011A1 HU 9000008 W HU9000008 W HU 9000008W WO 9111011 A1 WO9111011 A1 WO 9111011A1
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WO
WIPO (PCT)
Prior art keywords
layer
zone
thickness
lead
set forth
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Application number
PCT/HU1990/000008
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French (fr)
Inventor
Péter Teleki
Original Assignee
Teleki Peter
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Publication date
Application filed by Teleki Peter filed Critical Teleki Peter
Priority to PCT/HU1990/000008 priority Critical patent/WO1991011011A1/en
Publication of WO1991011011A1 publication Critical patent/WO1991011011A1/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/16—X-ray, infrared, or ultraviolet ray processes
    • G03C5/17—X-ray, infrared, or ultraviolet ray processes using screens to intensify X-ray images
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
    • G03C2001/03511—Bromide content

Definitions

  • the present invention refers to the field of the radiography and offers a solid-state structure for intensifying the effect of X-ray radiation, particularly for industrial applications, the structure proposed being a combination suited for use in radiographic recording of information with a silver halide, especially bromide recording material and comprising at least one metallic layer or sheet composed of or containing at least one metal excited under influence of the X-ray radiation.
  • the structure as proposed has first and second sides, the X-ray radiation striking on the first side, the second side being arranged at the surface of the radiographic recording material.
  • the structure comprises at least three structural layers and each of the first two structural layers, taken in sequence from the first side toward the second side, includes an element converting at least a part of a first kind of radioactive radiation into a second kind thereof.
  • the structures according to the art can be divided into two groups.
  • the first of them consists of the solutions equipped with a metallic foil (made e.g. of lead) and the second includes the structures comprising a foil made of a salt, e.g. of calcium tungstate (CaWO 4 ).
  • the metallic foil structures show relatively low amplification and very high effectiveness in filtering scattered radiation, the last resulting in deterioration of the picture quality because of high level halation.
  • the salt foil structures ensure very good amplification but the picture quality is many times not satisfactory.
  • the increased amplification with simultaneous improvement of the picture quality is the object of the European Patent No. 0.128.922 resulting from the PCT application No. PCT/HU83/00062 published under the number W084/02399.
  • a modification member consisting of more metallic thin foils made e.g. of lead is applied.
  • the improved picture quality is ensured in this case by the increased time of exposition and this is also not desired. The thicker the modification member the longer the exposition time, however the better the picture quality.
  • the combinations as disclosed comprise at least one metallic layer or sheet composed of or containing at least one metal having an atomic number in the range of 46 to 83 and at least one fluorescent layer or sheet, which in working relationship with the metal(s) consists of or contain at least one fluorescent substance determined by the general formula M (w-n) M n 'O w X, wherein M and M' are yttrium and differrent rare earth metals, X means sulphur or halogen.
  • the fluorescent stimulation is an important factor of excitation of the ligth emission ensured by the salt foil.
  • the way of excitation proposed by De Belder et al. was known earlier; its application itself is novel.
  • One of the metals M and M' can be excited, e.g. by silver emitting characteristic radiation which is capable of exciting this metal.
  • the idea is difficult to realize, in many cases the effectiveness of the excitation is low. It can be stated that the excitation exerted on the salt foil is an advantageous basis but the effectiveness of energy conversion can not be remarkably improved in an extent which can be regarded to be economically positive.
  • the fluorescent excitation can be ensured in a way whereby both components of the silver bromide registration substance are excited.
  • a modifying body is inserted for receiving the X-ray radiation and converting its energy at least partly into characteristic radiation having two components, the first ensuring excitation of the silver part and the second that of the bromine part of the photosensitive material.
  • the excitation is ensured by elements issuing radiation according to the K-edge levels of silver and bromine.
  • the invention is based on the recognition that in radiographic recording of information the sensitivity of the recording material (film) was not really taken into account. This sensitivity depends on the energy, its highest values can be about thousand times higher than the lowest.
  • a radiation should be generated showing a characteristics matching the excitation features of the recording material.
  • both kinds of radiation i.e. electrons and gamma radiation
  • the recording material there are components e- mitting electrons and/or gamma particles present.
  • the pi bonds of the chemical compounds, the holes emitting electrons can be excited, too.
  • the empty traps, the holes of the other kinds and the acceptors of chemical processes cause under excitation a process slowing or in given case reverting the direction of the chemical reaction. This means, excitation of silver and bromine in a simultaneous process is not desired.
  • the bromine ion having negative electric charge is the donor and the silver ion having positive electric charge the acceptor of electrons.
  • a solid-state structure for intensifying the effect of the X-ray radiation should be created which generates radiation "tuned” to the energetic characteristics of the halide component, especially bromine.
  • the tuned radiation means that the energy of the excited particles is at most two times higher than the required energy E of excitation but is not lower. The most advantageous is if the energy of the excited particles does not exceed E + E 1/2 , wherein E equals at least 2 keV.
  • the proposed invention is a structure for intensifying the effect of X-ray radiation, particularly for industrial applications, which has first and second sides, the X-ray radiation striking the structure on the first side, the second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, the structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from the first side toward the. second side, includes an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof.
  • the structure comprises a first structural layer system essentially consisted of lead covered by a lead oxide layer forming a first zone for generating primary electrons on the basis of the X-ray radiation and a second structural layer system forming a second zone for receiving the primary electrons and generating secondary electrons and characteristic radiation influencing the halide component of the radiographic recording material, which is particularly made of an alkali earth metal, especially strontium and a further layer consisted of the oxide of the alkali earth metal.
  • the first structural layer system is formed by a foil made of lead doped with at least one metal selected from the group consisted of cadmium, zinc and calcium, and the alkali earth metal is doped with calcium.
  • a further object of the present invention is also a structure having first and second sides, the X-ray radiation striking the structure on the first side, the second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, the structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from the first side toward the second side, includes an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof, wherein according to the present invention a first structural layer element constitutes a first zone for generating primary electrons on the basis of the X-ray radiation, the first zone comprising at least one heavy metal as tungsten, lead and tantalum and a second structural layer system forms a second zone made of at least three components for receiving the primary electrons and generating secondary electrons and an exciting zone for generating characteristic radiation influencing the halide component of the radiographic recording material, the exciting zone being at least partly made of strontium and/or yttrium.
  • the exciting zone consists of a light layer made of strontium and/or yttrium and a heavy layer made of molybdenum and/or niobium having lower thickness than the light layer.
  • the first structural layer element either is arranged between the exciting zone having thickness in the range of 0.010 to 0.020 mm, especially 0.014 to 0.016 mm and is made for having thickness in the range of 0.002 to 0.004 mm or it has thickness in the range of 0.003 to 0.020 mm, particularly 0.010 to 0.012 mm and is arranged on the first side adjacent to the exciting zone contacting the second zone, the exciting zone having thickness in the range of 0.004 to C.020 mm, particularly 0.008 to 0.010 mm.
  • the second zone with thickness in the range of 0.0002 to 0.0030 mm and an outer layer made of at least one metal selected from lead, cerium and aluminium and the oxide of the at least metal selected, an inner layer contacting the radiographic recording material made of lead and/or aluminium and the oxide of lead and/or aluminium and a cathodic layer arranged between the inner and outer layers, the cathodic layer being an oxide cathode or a photocathode, wherein the inner and outer layers advantageously have thickness essentially about 0.0001 mm, the thickness of the cathodic layer is essentially about 0.0002 mm.
  • a biasing layer is arranged, which has thickness in the range of 0.0005 to 0.0010 mm and being made of rubidium. This layer increases the effectiveness of excitation of bromine.
  • the first zone may comprise either at least one metal layer made of lead, tungsten and/or tantalum and an oxide layer consisted of the oxide of the metal(s) of the metal layer or at least one metal layer made of lead and an auxiliary layer made of tungsten and/or tantalum.
  • the scattered radiation can harm both the persons applying the X-ray radiation and the environment of the apparatuses, therefore it is advantageous to equip the proposed structure with a reduction attachment arranged before the first side of the structure and divided therefrom by a layer of insulating material - consisted of plastic or air gap - of thickness at least 0.02 mm, the reduction attachment consisting of thirty-two or more structural layers of thickness in the range of about 0.0001 to 0.010 mm, particularly of 0.001 to 0.002 mm forming a body of thickness in the range of about 0.03 to 0.30 mm, particularly about 0.1 mm, wherein the structural layers are separated by respec tive oxide or adhesive layers and made of at least three metals selected from of lead, aluminium, copper and nickel in a space sequence, in which at least one layer made of a metal of higher atomic number is arranged between et least two layers consisted of metal of lower atomic number.
  • the structure built-up according to the principles shown above ensures a very effective excitation of the halide component of the radiographic recording material without a remarkable deterioration of the picture quality, intensification of the electron emission, reduction of the scattered radiation. It can be applied both in medical and industrial investigations requiring photosensitive material coating a film on both sides or on one side only. In the first case it is preferred to apply the structure as proposed on both sides of the film.
  • FIG. 1 illustrates a cross-section of a basic embodiment of the proposed structure completed with a reduction attachment
  • FIG. 2 shows a cross-section of another basic embodiment of the proposed structure comprising also a reduction attachment
  • FIG. 3 is the cross-section of an advantageous realization of the secondary electron generating zone of the proposed structure
  • FIG. 4 is the cross-section of an advantageous realization of the exciting zone of the proposed structure
  • FIG. 5 illustrates a cress-section of a basic embo diment of the primary electron generating zone of the proposed structure
  • FIG. 6 is a cross-section of another basic embodiment of the primary electron generating zone the structure of the invention.
  • the structure proposed by the invention basically comprises two structural layer systems for generating electrons. It is applied at the surface of a radiographic recording material, matching it generally from one or two sides depending on the fact whether the photosensitive emulsion prepared for generating a radiographic picture covers the material from one or two sides. Of course, a one side arrangement is always possible.
  • the first structural layer system ensures generating primary electrons and it forms a first zone 3 (FIG. 1 and 2).
  • the second structural layer system constitutes a part of the structure of the invention which receives the primary electrons and generates secondary electrons and characteristic radiation influencing a halide component of the radiographic recording material being especially a film 4 made on the basis of silver bromide. It includes a second zone 1 contacting or lying close to the surface of the film 4.
  • the proposed structure has a first side receiving X-ray radiation R reflected or declined by an object to be investigated (not shown on the drawings).
  • the radiographic recording material contacts its second side.
  • the object can be a living body or a piece of an inorganic material.
  • the structure of the invention can be completed with a reduction attachment 7 for reducing scattered radiation which is divided from the structure by the means of an insulating body 6 made of a plastic (e.g. polyethylene or mylar) of at least 0.02 mm thickness or constituted by an air gap of appropriate width.
  • a plastic e.g. polyethylene or mylar
  • the X-ray radiation impacts the insulating body 6 before entering the structure proposed by the invention.
  • the first zone 1 consists of a heavy metal as tungsten, tantalum and especially lead and is covered on its inner side directed to the film 4 with an oxide layer lying under two further layers made respectively of an alkali earth metal, especially strontium and its oxide. The last is arranged at the film 4.
  • This embodiment is advantageously realized on the basis of the known lead foils of thickness about 0.027 mm covered by the further layers having general thickness about 0.001 to 0.002 mm.
  • the heavy metal may be doped with cadmium, zinc and calcium, the strontium with calcium.
  • the main idea of the present invention is, however, more than to improve the known lead foil systems. It is directed to offering a structure for remarkable improvements in the processes of registering information during radiographic investigations.
  • Two basic embodiments of the structure built-up according to the invention are shown in FIG. 1 and 2. This a body of preferred thickness in the range of 0.01 to 0.05 mm, particularly 0.020 to 0.024 mm.
  • the second structural layer system includes two main layer parts.
  • the first of them forms the second zone 1 lying, as mentioned, at the film 4 and serving for generating secondary electrons.
  • the second part constitutes an exciting zone 2 for generating characteristic radiation.
  • the two embodiments shown in FIG. 1 and 2 differ in the space sequence of the first zone 3 and the exciting zone 2, any one of them may be the first receiving the X-ray radiation R.
  • inner side means the part lying nearer to the film 4 and outer side the part arranged nearer to the source of the X-ray radiation R.
  • the second zone 1 can be made (FIG. 3) with a biasing laver 5 of thickness in the range of 0.0C05 to 0.001 mm made of rubidium. It comprises an outer layer 13 lying at the film 4 and consisted of lead, cerium and/or aluminium and the oxide(s) of the metal(s) selected, a middle, cathodic layer 12 forming an oxide cathode or a photocathode and an inner layer 11 contacting the exciting zone 2 (FIG. 1.) or the first zone 3 (FIG. 2) and consisting of lead and/or aluminium and the oxide(s) of the metal(s) selected.
  • the cathodic layer 12 as oxide cathode is made of beryllium, magnesium or strontium and the oxide of the metal selected and as photocathode it forms blends with preferred composition on the basis of copper and rubidium, silver and rubidium, bismuth and rubidium, tellurium and rubidium, silver and caesium or antimony and caesium.
  • the second zone 1 is as thick as 0.0002 to 0.003 mm, wherein it is especially preferred to apply the inner and outer layers 13, 11 with thicknesses about 0.0001 mm and the cathodic layer 12 having thickness about 0.0002 mm.
  • the exciting zone 2 is made generally as a homogeneous body consisted of strontium and/or yttrium. It is also possible and advantageous to prepare this zone as an inhomogeneous body consisting of a light layer 21 which consists of strontium and/or yttrium and a heavy layer 22 prepared from molybdenum or niobium covering the light layer 21 (FIG. 4.).
  • the thickness of the heavy layer 22 makes out essentially about 0.001 to 0.002 mm.
  • the preferred thickness of the exciting zone 2 depends on the structure prepared. Advantageously it is equal either 0.004 to 0.020 mm, particularly in the range of 0.008 to 0.010 mm when the exciting zone 2 is arranged in the middle part of the structure proposed by the invention or 0.010 to 0. 0020 mm, particularly in the range of 0.014 to 0.016 mm when it covers the structure from the first side (i.e. the exciting zone 2 and the second zone 1 are divided by the first zone 3).
  • the first zone 3 can be also a homogeneous body and is as thick as about 0.003 to 0.020 mm. particularly 0.010 to 0.012 mm when prepared as the outer layer element forming the first side or as about 0.002 to 0.004 mm if arranged in the middle part of the structure of the invention.
  • the same thickness values are valid for a first zone 3 consited of more layers wherein advantageously metal layers 31 divided by oxide layers 32 are applied.
  • the metal layers 31 are made of lead, however, they can include or consisted of tungsten and tantalum. If the metal layers 31 are prepared from lead, on the inner side of the first zone 1 an auxiliary layer 33 made of tantalum or tungsten can be applied (FIG. 5).
  • the metal layers 31 are generally thicker than 0.0001 mm and the preferred thickness range is of 0.001 to 0.002 mm.
  • Another preferred possiblity is shown in FIG. 6: the first zone 3 comprises a lead body 34 covered on its inner side by the auxiliary layer 33.
  • the scattered radiation can be the source of different problems. Hence, shielding the environment therefrom is desired.
  • the reduction attachment 7 consisted of at least 32 layers. Each of these layers has thickness in the range of 0.0001 to 0.0100 nm, particularly of 0.001 to 0.002 mm giving a general thickness from about 0.03 to 0.30 mm, particularly about 0.10 mm.
  • the layers of this layer system are made of at least three metals crystallizing according to the FCC (face-centered) system, generally selected from lead, silver, copper, nickel and aluminium, wherein advantageously lead is always present.
  • the layers should preferably be arranged in a space sequence according to their atomic numbers which are decreasing or increasing from one layer to the other or from one layer group to the other. In a layer group the layers are divided by oxide and/or adhesive layers.
  • This structure reduces the scattered radiation which can not further penetrate the structure of the invention: the characteristic radiation generated in it is absorbed by the attachmemt itself and the electrons generated by the insulating body 6.
  • An especially preferred embodiment of the reduction attachment 7 consists of the following:
  • the structure of the invention is applied on one or two sides of the film, depending on the fact whether the film is coated with photosensitive emulsion on one or two sides.
  • the film 4 is coated from both by an emulsion for generating a radiographic picture it is preferred to apply the structure of the invention on both sides of the film 4, e.g. in the sequence as given below:
  • This arrangement assures pictures of high quality independently on the kind of the X-ray radiation, i.e. with soft radiation applied in medicine or with hard X-ray beams required in the industrial radiography.
  • the invention will be further described with special reference to the radiographic recording material based on silver bromide which is generally applied in the radiographic investigations.
  • the excitation of the silver bromide based recording material results also in the excitation of the other elements present therein, especially copper, cadmium, sulphur, iodine and gold. Only iodine plays role similar to that of bromine in this system, i.e.
  • the bromine component of the radiographic recording material (film 4) is excited by radiation emitted from the K shell of the strontium and/or yttrium (Sr, Y).
  • the a1 and a2 levels of the rubidium, because of being higher then a1 level and lower then K level of the bromine is a "biasing" component which facilitates the excitation by yttrium or strontium and gives a remarkable improvement of the picture quality.
  • yttrium and/or strontium can or may advantageously be excited, too. This is assured by niobium and molybdenum influencing strontium or by molybdenum in the case of yttrium. Niobium and molybdenum are effective also in excitation of rubidium and in small extent of bromine. If iodine is present it is advantageous to ensure the excitation by cerium, the other lantanoids from lanthanum to neodymium are rather not preferred.
  • the L shell of the heavy metal present i.e. lead, tantalum or tungsten can be effectively excited by the K shell emission of rubidium, strontium and yttrium.
  • the electron emission of the heavy metal resulting from this excitation is advantageously influences the process of generating picture in the photosensitive recording material. Therefore lead is especially preferred.
  • a further advantage thereof is the fact that it is capable, by the L shell emission, of exciting bromine.

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Conversion Of X-Rays Into Visible Images (AREA)

Abstract

A structure is proposed for intensifying the effect of X-ray radiation, particularly for industrial applications. It has first and second sides, the X-ray radiation (R) striking on the first side, the second side being arranged at the surface of a radiographic recording material (4) made with a silver halide, especially bromide component. The structure comprises at least three structural layers, wherein each of the first two structural layers, taken in sequence from the first side toward the second side, includes an element converting at least a part of a first kind of radioactive radiation into a second kind thereof. The first structural layer element forms a first zone (3) for generating primary electrons on the basis of the X-ray radiation (R), the first zone (3) comprising at least one heavy metal as tungsten, lead and tantalum and a second structural layer system forming a second zone (1) made of at least three components for receiving the primary electrons and generating secondary electrons and an exciting zone (2) for generating characteristic radiation influencing the halide component of the radiographic recording material (4), the exciting zone (2) being at least partly made of strontium and/or yttrium.

Description

SOLID-STATE STRUCTURE FOR INTENSIFYING THE
EFFECT OF X-BAY RADIATION, PARTICULARLY FOR
INDUSTRIAL APPLICATIONS
FIELD OF THE INVENTION The present invention refers to the field of the radiography and offers a solid-state structure for intensifying the effect of X-ray radiation, particularly for industrial applications, the structure proposed being a combination suited for use in radiographic recording of information with a silver halide, especially bromide recording material and comprising at least one metallic layer or sheet composed of or containing at least one metal excited under influence of the X-ray radiation. The structure as proposed has first and second sides, the X-ray radiation striking on the first side, the second side being arranged at the surface of the radiographic recording material. The structure comprises at least three structural layers and each of the first two structural layers, taken in sequence from the first side toward the second side, includes an element converting at least a part of a first kind of radioactive radiation into a second kind thereof.
BACKGROUND OF THE INVENTION The structures proposed in the art for intensifying X-ray radiation in radiographic recording information with a silver halide, especially silver bromide recording material are intended to diminish the time of X-ray exposition with ensuring simultaneously the required quality of the radiographic picture. The basic problem of the art lies in the fact that increased intensification (amplification) offered by the structure is linked with deterioration of the picture quality.
The structures according to the art can be divided into two groups. The first of them consists of the solutions equipped with a metallic foil (made e.g. of lead) and the second includes the structures comprising a foil made of a salt, e.g. of calcium tungstate (CaWO4). The metallic foil structures show relatively low amplification and very high effectiveness in filtering scattered radiation, the last resulting in deterioration of the picture quality because of high level halation. The salt foil structures ensure very good amplification but the picture quality is many times not satisfactory.
From the literature of the art there are some solutions known wherein the drawbacks of a structure belonging to one of the mentioned groups are intended to be avoided or reduced at least.
The increased amplification with simultaneous improvement of the picture quality is the object of the European Patent No. 0.128.922 resulting from the PCT application No. PCT/HU83/00062 published under the number W084/02399. According to this specification between a body to be investigated by the means of X-ray radiation and a member for receiving the radiation a modification member consisting of more metallic thin foils made e.g. of lead is applied. The improved picture quality is ensured in this case by the increased time of exposition and this is also not desired. The thicker the modification member the longer the exposition time, however the better the picture quality.
A very important solution was described in the U.S. Letters Patent 3-872.309 issued to De Belder et al. in 1975, wherein radiographic intensifying screens suited for use in radiographic recording material were proposed. The combinations as disclosed comprise at least one metallic layer or sheet composed of or containing at least one metal having an atomic number in the range of 46 to 83 and at least one fluorescent layer or sheet, which in working relationship with the metal(s) consists of or contain at least one fluorescent substance determined by the general formula M(w-n)Mn'OwX, wherein M and M' are yttrium and differrent rare earth metals, X means sulphur or halogen. In this solution the fluorescent stimulation is an important factor of excitation of the ligth emission ensured by the salt foil. The way of excitation proposed by De Belder et al. was known earlier; its application itself is novel. One of the metals M and M' can be excited, e.g. by silver emitting characteristic radiation which is capable of exciting this metal. The idea is difficult to realize, in many cases the effectiveness of the excitation is low. It can be stated that the excitation exerted on the salt foil is an advantageous basis but the effectiveness of energy conversion can not be remarkably improved in an extent which can be regarded to be economically positive.
The fluorescent excitation can be ensured in a way whereby both components of the silver bromide registration substance are excited. According to a solution proposed by P. Teleki in the U. S. patent document No. 4.764.946 a modifying body is inserted for receiving the X-ray radiation and converting its energy at least partly into characteristic radiation having two components, the first ensuring excitation of the silver part and the second that of the bromine part of the photosensitive material. The excitation is ensured by elements issuing radiation according to the K-edge levels of silver and bromine.
The methods of applying a salt foil or exciting the active components of a photosensitive material show some drawbacks following from the fact that the electrons entering the photosensitive material excite both silver and bro¬mine. The scattered radiation is further very intensive and this is also disadvantageous.
SUMMARY OF THE INVENTION The invention is based on the recognition that in radiographic recording of information the sensitivity of the recording material (film) was not really taken into account. This sensitivity depends on the energy, its highest values can be about thousand times higher than the lowest.
In the excitation of the recording material a radiation should be generated showing a characteristics matching the excitation features of the recording material. Because of applying electrons generated by the X-ray radiation both kinds of radiation (i.e. electrons and gamma radiation) are present. In the recording material there are components e- mitting electrons and/or gamma particles present. The pi bonds of the chemical compounds, the holes emitting electrons can be excited, too. The empty traps, the holes of the other kinds and the acceptors of chemical processes cause under excitation a process slowing or in given case reverting the direction of the chemical reaction. This means, excitation of silver and bromine in a simultaneous process is not desired.
When taking into account the silver halide recording materials it is obvious that the bromine ion having negative electric charge is the donor and the silver ion having positive electric charge the acceptor of electrons. Hence, a solid-state structure for intensifying the effect of the X-ray radiation should be created which generates radiation "tuned" to the energetic characteristics of the halide component, especially bromine. This recognition is based on the fact that radiation "tuned" to the silver component results in weakening effect. The tuned radiation means that the energy of the excited particles is at most two times higher than the required energy E of excitation but is not lower. The most advantageous is if the energy of the excited particles does not exceed E + E1/2, wherein E equals at least 2 keV.
Thus, the proposed invention is a structure for intensifying the effect of X-ray radiation, particularly for industrial applications, which has first and second sides, the X-ray radiation striking the structure on the first side, the second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, the structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from the first side toward the. second side, includes an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof. According to the invention the structure comprises a first structural layer system essentially consisted of lead covered by a lead oxide layer forming a first zone for generating primary electrons on the basis of the X-ray radiation and a second structural layer system forming a second zone for receiving the primary electrons and generating secondary electrons and characteristic radiation influencing the halide component of the radiographic recording material, which is particularly made of an alkali earth metal, especially strontium and a further layer consisted of the oxide of the alkali earth metal.
It is very advantageous when the first structural layer system is formed by a foil made of lead doped with at least one metal selected from the group consisted of cadmium, zinc and calcium, and the alkali earth metal is doped with calcium.
A further object of the present invention is also a structure having first and second sides, the X-ray radiation striking the structure on the first side, the second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, the structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from the first side toward the second side, includes an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof, wherein according to the present invention a first structural layer element constitutes a first zone for generating primary electrons on the basis of the X-ray radiation, the first zone comprising at least one heavy metal as tungsten, lead and tantalum and a second structural layer system forms a second zone made of at least three components for receiving the primary electrons and generating secondary electrons and an exciting zone for generating characteristic radiation influencing the halide component of the radiographic recording material, the exciting zone being at least partly made of strontium and/or yttrium. The thickness of this structure is advantageosly in the range of 0.01 to 0.05 mm, particularly 0.020 to 0.024 mm.
In an especially advantageous embodiment of the proposed structure the exciting zone consists of a light layer made of strontium and/or yttrium and a heavy layer made of molybdenum and/or niobium having lower thickness than the light layer.
In the structure according to the invention it is particularly preferred that the first structural layer element either is arranged between the exciting zone having thickness in the range of 0.010 to 0.020 mm, especially 0.014 to 0.016 mm and is made for having thickness in the range of 0.002 to 0.004 mm or it has thickness in the range of 0.003 to 0.020 mm, particularly 0.010 to 0.012 mm and is arranged on the first side adjacent to the exciting zone contacting the second zone, the exciting zone having thickness in the range of 0.004 to C.020 mm, particularly 0.008 to 0.010 mm. As for the further dimension particulars it is preferred in the structure of the invention to prepare the second zone with thickness in the range of 0.0002 to 0.0030 mm and an outer layer made of at least one metal selected from lead, cerium and aluminium and the oxide of the at least metal selected, an inner layer contacting the radiographic recording material made of lead and/or aluminium and the oxide of lead and/or aluminium and a cathodic layer arranged between the inner and outer layers, the cathodic layer being an oxide cathode or a photocathode, wherein the inner and outer layers advantageously have thickness essentially about 0.0001 mm, the thickness of the cathodic layer is essentially about 0.0002 mm. It is also preferred when before the outer layer a biasing layer is arranged, which has thickness in the range of 0.0005 to 0.0010 mm and being made of rubidium. This layer increases the effectiveness of excitation of bromine.
In the structure as proposed by the invention the first zone may comprise either at least one metal layer made of lead, tungsten and/or tantalum and an oxide layer consisted of the oxide of the metal(s) of the metal layer or at least one metal layer made of lead and an auxiliary layer made of tungsten and/or tantalum.
The scattered radiation can harm both the persons applying the X-ray radiation and the environment of the apparatuses, therefore it is advantageous to equip the proposed structure with a reduction attachment arranged before the first side of the structure and divided therefrom by a layer of insulating material - consisted of plastic or air gap - of thickness at least 0.02 mm, the reduction attachment consisting of thirty-two or more structural layers of thickness in the range of about 0.0001 to 0.010 mm, particularly of 0.001 to 0.002 mm forming a body of thickness in the range of about 0.03 to 0.30 mm, particularly about 0.1 mm, wherein the structural layers are separated by respec tive oxide or adhesive layers and made of at least three metals selected from of lead, aluminium, copper and nickel in a space sequence, in which at least one layer made of a metal of higher atomic number is arranged between et least two layers consisted of metal of lower atomic number.
The structure built-up according to the principles shown above ensures a very effective excitation of the halide component of the radiographic recording material without a remarkable deterioration of the picture quality, intensification of the electron emission, reduction of the scattered radiation. It can be applied both in medical and industrial investigations requiring photosensitive material coating a film on both sides or on one side only. In the first case it is preferred to apply the structure as proposed on both sides of the film.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure proposed by the invention will be further shown in more detail with reference to the attached drawings and several embodiments described by way of example only. In the drawings
FIG. 1 illustrates a cross-section of a basic embodiment of the proposed structure completed with a reduction attachment,
FIG. 2 shows a cross-section of another basic embodiment of the proposed structure comprising also a reduction attachment,
FIG. 3 is the cross-section of an advantageous realization of the secondary electron generating zone of the proposed structure, FIG. 4 is the cross-section of an advantageous realization of the exciting zone of the proposed structure,
FIG. 5 illustrates a cress-section of a basic embo diment of the primary electron generating zone of the proposed structure and
FIG. 6 is a cross-section of another basic embodiment of the primary electron generating zone the structure of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The structure proposed by the invention basically comprises two structural layer systems for generating electrons. It is applied at the surface of a radiographic recording material, matching it generally from one or two sides depending on the fact whether the photosensitive emulsion prepared for generating a radiographic picture covers the material from one or two sides. Of course, a one side arrangement is always possible.
The first structural layer system ensures generating primary electrons and it forms a first zone 3 (FIG. 1 and 2). The second structural layer system constitutes a part of the structure of the invention which receives the primary electrons and generates secondary electrons and characteristic radiation influencing a halide component of the radiographic recording material being especially a film 4 made on the basis of silver bromide. It includes a second zone 1 contacting or lying close to the surface of the film 4. The proposed structure has a first side receiving X-ray radiation R reflected or declined by an object to be investigated (not shown on the drawings). The radiographic recording material contacts its second side. The object can be a living body or a piece of an inorganic material.
The structure of the invention can be completed with a reduction attachment 7 for reducing scattered radiation which is divided from the structure by the means of an insulating body 6 made of a plastic (e.g. polyethylene or mylar) of at least 0.02 mm thickness or constituted by an air gap of appropriate width. In this case the X-ray radiation impacts the insulating body 6 before entering the structure proposed by the invention.
In a first realization of the invention the first zone 1 consists of a heavy metal as tungsten, tantalum and especially lead and is covered on its inner side directed to the film 4 with an oxide layer lying under two further layers made respectively of an alkali earth metal, especially strontium and its oxide. The last is arranged at the film 4. This embodiment is advantageously realized on the basis of the known lead foils of thickness about 0.027 mm covered by the further layers having general thickness about 0.001 to 0.002 mm. The heavy metal may be doped with cadmium, zinc and calcium, the strontium with calcium.
The main idea of the present invention is, however, more than to improve the known lead foil systems. It is directed to offering a structure for remarkable improvements in the processes of registering information during radiographic investigations. Two basic embodiments of the structure built-up according to the invention are shown in FIG. 1 and 2. This a body of preferred thickness in the range of 0.01 to 0.05 mm, particularly 0.020 to 0.024 mm.
The second structural layer system includes two main layer parts. The first of them forms the second zone 1 lying, as mentioned, at the film 4 and serving for generating secondary electrons. The second part constitutes an exciting zone 2 for generating characteristic radiation. The two embodiments shown in FIG. 1 and 2 differ in the space sequence of the first zone 3 and the exciting zone 2, any one of them may be the first receiving the X-ray radiation R. In the further description inner side means the part lying nearer to the film 4 and outer side the part arranged nearer to the source of the X-ray radiation R.
The second zone 1 can be made (FIG. 3) with a biasing laver 5 of thickness in the range of 0.0C05 to 0.001 mm made of rubidium. It comprises an outer layer 13 lying at the film 4 and consisted of lead, cerium and/or aluminium and the oxide(s) of the metal(s) selected, a middle, cathodic layer 12 forming an oxide cathode or a photocathode and an inner layer 11 contacting the exciting zone 2 (FIG. 1.) or the first zone 3 (FIG. 2) and consisting of lead and/or aluminium and the oxide(s) of the metal(s) selected. The cathodic layer 12 as oxide cathode is made of beryllium, magnesium or strontium and the oxide of the metal selected and as photocathode it forms blends with preferred composition on the basis of copper and rubidium, silver and rubidium, bismuth and rubidium, tellurium and rubidium, silver and caesium or antimony and caesium. The second zone 1 is as thick as 0.0002 to 0.003 mm, wherein it is especially preferred to apply the inner and outer layers 13, 11 with thicknesses about 0.0001 mm and the cathodic layer 12 having thickness about 0.0002 mm.
The exciting zone 2 is made generally as a homogeneous body consisted of strontium and/or yttrium. It is also possible and advantageous to prepare this zone as an inhomogeneous body consisting of a light layer 21 which consists of strontium and/or yttrium and a heavy layer 22 prepared from molybdenum or niobium covering the light layer 21 (FIG. 4.). The thickness of the heavy layer 22 makes out essentially about 0.001 to 0.002 mm. The preferred thickness of the exciting zone 2 depends on the structure prepared. Advantageously it is equal either 0.004 to 0.020 mm, particularly in the range of 0.008 to 0.010 mm when the exciting zone 2 is arranged in the middle part of the structure proposed by the invention or 0.010 to 0. 0020 mm, particularly in the range of 0.014 to 0.016 mm when it covers the structure from the first side (i.e. the exciting zone 2 and the second zone 1 are divided by the first zone 3).
The first zone 3 can be also a homogeneous body and is as thick as about 0.003 to 0.020 mm. particularly 0.010 to 0.012 mm when prepared as the outer layer element forming the first side or as about 0.002 to 0.004 mm if arranged in the middle part of the structure of the invention. The same thickness values are valid for a first zone 3 consited of more layers wherein advantageously metal layers 31 divided by oxide layers 32 are applied. Advantageously the metal layers 31 are made of lead, however, they can include or consisted of tungsten and tantalum. If the metal layers 31 are prepared from lead, on the inner side of the first zone 1 an auxiliary layer 33 made of tantalum or tungsten can be applied (FIG. 5). The metal layers 31 are generally thicker than 0.0001 mm and the preferred thickness range is of 0.001 to 0.002 mm. Another preferred possiblity is shown in FIG. 6: the first zone 3 comprises a lead body 34 covered on its inner side by the auxiliary layer 33.
The scattered radiation can be the source of different problems. Hence, shielding the environment therefrom is desired. This is ensured by the reduction attachment 7 consisted of at least 32 layers. Each of these layers has thickness in the range of 0.0001 to 0.0100 nm, particularly of 0.001 to 0.002 mm giving a general thickness from about 0.03 to 0.30 mm, particularly about 0.10 mm. The layers of this layer system are made of at least three metals crystallizing according to the FCC (face-centered) system, generally selected from lead, silver, copper, nickel and aluminium, wherein advantageously lead is always present. The layers should preferably be arranged in a space sequence according to their atomic numbers which are decreasing or increasing from one layer to the other or from one layer group to the other. In a layer group the layers are divided by oxide and/or adhesive layers. Some preferred solutions are the reduction attachments 7 made on the basis of layers arranged in the following sequences:
Pb - Al - Pb - Al - ...
Pb - Cu - Al - Cu - Pb - Cu - ... Pb - Ni - Al - Ni - Pb - Ni - ...
Pb - Cu - Ni - Al - Ni - Cu - Pb - ...
This structure reduces the scattered radiation which can not further penetrate the structure of the invention: the characteristic radiation generated in it is absorbed by the attachmemt itself and the electrons generated by the insulating body 6. An especially preferred embodiment of the reduction attachment 7 consists of the following:
10 layers made of Alx - 0.01 mm 10 layers made of Cu - 0.02 mm
10 layers made of Pbx - 0.04 mm 10 layers made of Cu - 0.02 mm . 10 layers made of Alx - 0.01 mm The thickness of this body is about 0.1 mm. The symmetry of the arrangement is not a strict requirement, however, it is advantageous. By the preferred possibility of doping with copper is marked.
The structure of the invention is applied on one or two sides of the film, depending on the fact whether the film is coated with photosensitive emulsion on one or two sides.
If the film 4 is coated from both by an emulsion for generating a radiographic picture it is preferred to apply the structure of the invention on both sides of the film 4, e.g. in the sequence as given below:
reduction attachment 7 0.1 mm
insulating body 6 0.03 mm
structure with zones 1, 2 and 3 0.02 mm
FILM 4
structure with zones 1, 2 and 3 0.02 mm
insulating body 6 0.03 mm
reduction attachment 7 0.1 mm
rear plate made of lead 0.1 mm
This arrangement assures pictures of high quality independently on the kind of the X-ray radiation, i.e. with soft radiation applied in medicine or with hard X-ray beams required in the industrial radiography.
The invention will be further described with special reference to the radiographic recording material based on silver bromide which is generally applied in the radiographic investigations. The excitation of the silver bromide based recording material results also in the excitation of the other elements present therein, especially copper, cadmium, sulphur, iodine and gold. Only iodine plays role similar to that of bromine in this system, i.e. silver iodide is also a photosensitive component and a proposal for ensuring its excitation is given, too, however the atomic numbers of iodine (Z = 53) and silver (Z = 47) lie relatively close one to another and because of anomaly characterizing the absorption coefficients of the ionized elements in the range of Z = 42 to Z = 65 the excitation of silver can be carried out more effectively than that of iodine (the absorption coeffecient of silver is higher than that of iodine).
The absorption and emission data of the elements listed up above are given hereinafter, wherein before symbols of the elements the atomic number Z will always be indicated; the energy level of absorption defined by the electron shell K of an element, representing the limit value of excitation of this element, expressed in unit keV, will be indicated with K. The most probably energy levels of e- mission corresponding to the transition between the electron shells K and L of the excited element, expressed also in unit keV, are marked with a1 and a2.
Figure imgf000017_0001
a2 = 72.79 keV L111 = 13.04 keV The effective excitation of photosensitive material is ensured if the energy of exciting particles is in the range of K to 2K, preferably K to K1/2, wherein K is the energy value given above for the halide component. In the case of bromine this means the preferred range of 13-47 to 17-14 keV and in the case of iodine the range of 33-17 to 38.93 keV (the role of iodine is rather subdominant).
According to the invention the bromine component of the radiographic recording material (film 4) is excited by radiation emitted from the K shell of the strontium and/or yttrium (Sr, Y). The a1 and a2 levels of the rubidium, because of being higher then a1 level and lower then K level of the bromine is a "biasing" component which facilitates the excitation by yttrium or strontium and gives a remarkable improvement of the picture quality.
A further recognition of the invention is that yttrium and/or strontium can or may advantageously be excited, too. This is assured by niobium and molybdenum influencing strontium or by molybdenum in the case of yttrium. Niobium and molybdenum are effective also in excitation of rubidium and in small extent of bromine. If iodine is present it is advantageous to ensure the excitation by cerium, the other lantanoids from lanthanum to neodymium are rather not preferred.
In the structure of the invention the L shell of the heavy metal present, i.e. lead, tantalum or tungsten can be effectively excited by the K shell emission of rubidium, strontium and yttrium. The electron emission of the heavy metal resulting from this excitation is advantageously influences the process of generating picture in the photosensitive recording material. Therefore lead is especially preferred. A further advantage thereof is the fact that it is capable, by the L shell emission, of exciting bromine.

Claims

WHAT I CLAIM IS :
1. A structure for intensifying the effect of X-ray radiation, particularly for industrial applications, said structure having first and second sides, said X-ray radiation striking said structure on said first side, said second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, said structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from said first side toward said second side, comprises an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof,
characterized in
comprising a first structural layer system forming a first zone for generating primary electrons on the basis of said X-ray radiation, said first zone comprising at least one heavy metal selected from the group consisting of lead, tungsten and tantalum and a second structural layer system forming a second zone for receiving said primary electrons and generating secondary electrons and characteristic radiation influencing said halide component of said radio- graphic recording material.
2. The structure as set forth in claim 1,
characterized in
that said first structural layer system comprises a layer consisted essentially of lead covered by a lead oxide layer and said second structural layer system comprises at least one layer consisted of an alkali earth metal, especially strontium and a further layer consisted of the oxide of said alkali earth metal.
3. The structure as set forth in claim 2,
c h a r a c t e r i z e d in that said first structural layer system is formed by a foil made of lead doped with at least one metal selected from the group consisted of cadmium, zinc and calcium, and said alkali earth metal is doped with calcium.
4. A structure for intensifying the effect of X-ray radiation, particularly for industrial applications, said structure having first and second sides, said X-ray radiation striking said structure on said first side, said second side being arranged at the surface of a radiographic recording material made with a silver halide, especially bromide component, said structure comprising at least three structural layers, wherein each of the first two structural layers, taken in sequence from said first side toward said second side, comprises an element which converts at least a part of a first kind of radioactive radiation into a second kind thereof,
characterized in
comprising a first structural layer element forming a first zone for generating primary electrons on the basis of said X-ray radiation, said first zone comprising at least one heavy metal selected from the group consisting of tungsten, lead and tantalum and a second structural layer system forming a second zone made of at least three components for receiving said primary electrons and generating secondary electrons and an exciting zone for generating characteristic radiation influencing said halide component of said radiographic recording material, said exciting zone being at least partly made of at least one metal selected from the group consisted of strontium and yttrium.
5. The structure as set forth in claim 4, characterized in
that said exciting zone consists of a light layer made of strontium and/or yttrium and a heavy layer made of molybdenum and/or niobium having lower thickness than said light layer.
6. The structure as set forth in claim 4,
characterized in
that said first structural layer element is arranged between said exciting zone having thickness in the range of 0.010 to 0.020 mm, especially 0.014 to 0.016 mm and is made for having thickness in the range of 0.002 to 0.004 mm.
7. The structure as set forth in claim 4, characterized in
that said first structural layer element having thickness in the range of 0.003 to 0.020 mm, particularly 0.010 to 0.012 mm is arranged on said first side adjacent to said exciting zone contacting said second zone, said exciting zone having thickness in the range of 0.004 to 0.020 mm, particularly 0.008 to 0.010 mm.
8. The structure as set forth in claim 4, characterized in
that said first, second and exciting zones form a body of summarized thickness in the range of 0.01 to 0.05 mm, particularly of 0.020 to 0.024 mm.
9. The structure as set forth in claim 4, characterized in
that said second zone has thickness in the range of 0.0002 to 0.0030 nm and comprises an outer layer made of at least one metal selected from the group consisted of lead, cerium and aluminium and the oxide of the at least metal selected, an inner layer contacting said radiographic recording material made of lead and/or aluminium and the oxide of lead and/or aluminium and a cathodic layer arranged between said inner and outer layers, the cathodic layer being an oxide cathode or a photocathode.
10. The structure as set forth in claim 8,
characterized in
that said inner and outer layers have thickness essentially about 0.0001 mm and the thickness of the cathodic layer is essentially about 0.0002 mm.
11. The structure as set forth in claim 8,
characterized in
that before said outer layer a biasing layer is arranged, said biasing layer having thickness in the range of 0.0005 to 0.0010 mm and being made of .rubidium.
12. The structure as set forth in claim 4,
characterized in
that said first zone comprises at least one metal layer made of at least one metal selected from the group consisted of lead, tungsten and tantalum and an oxide layer consisted of the oxide of said at least one selected metal.
13. The structure as set forth in claim 4,
characterized in
that said first zone comprises at least one metal layer made of lead and an auxiliary layer made of tungsten and/or tantalum.
14. The structure as set forth in any one of the precedent claims,
characterized in
comprising a reduction attachment arranged before said first side and divided therefrom by an insulating layer of thickness at least 0.02 mm, said reduction attachment consisting of at least thirty-two structural layers of thickness in the range of about 0.0001 to 0.010 mm, particularly of 0.001 to 0.002 mm forming a body of thickness in the range of about 0.03 to 0.30 nm, particularly about 0.1 mm, wherein said structural layers are separated by respective oxide or adhesive layers and made of at least three metals selected from the group consisted of lead, silver, copper, nickel and aluminium in a space sequence, in which at least one layer made of a metal of higher atomic number is arranged between et least two layers consisted of metal of lower atomic number.
15. The structure as set forth in claim 4,
characterized in comprising at least in said exciting zone an element issuing characteristic radiation with energy in the range of E to E + E1/2 wherein E means the absorption energy level defined by the electron shell K of said halide component.
PCT/HU1990/000008 1990-01-22 1990-01-22 Solid-state structure for intensifying the effect of x-ray radiation, particularly for industrial applications WO1991011011A1 (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0011909A1 (en) * 1978-08-11 1980-06-11 E.I. Du Pont De Nemours And Company X-ray intensifying screen based on a tantalate phosphor and process for producing the phosphor
GB2082617A (en) * 1980-08-25 1982-03-10 Gen Electric X-ray image converters utilizing rare earth phosphor mixtures
EP0081227A1 (en) * 1981-12-07 1983-06-15 Albert Macovski Energy-selective X-ray recording and readout system
EP0094259A1 (en) * 1982-05-12 1983-11-16 E.I. Du Pont De Nemours And Company X-ray intensifying screens based on phosphor mixtures
EP0160327A1 (en) * 1984-03-05 1985-11-06 Mitsubishi Cable Industries, Ltd. Laminar radiation-shielding article
EP0174875A2 (en) * 1984-09-14 1986-03-19 Konica Corporation Method for converting radiographic image and radiation energy storage panel having stimulable phosphor-containing layer
EP0347171A2 (en) * 1988-06-13 1989-12-20 Konica Corporation Radiation image storage panel

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0011909A1 (en) * 1978-08-11 1980-06-11 E.I. Du Pont De Nemours And Company X-ray intensifying screen based on a tantalate phosphor and process for producing the phosphor
GB2082617A (en) * 1980-08-25 1982-03-10 Gen Electric X-ray image converters utilizing rare earth phosphor mixtures
EP0081227A1 (en) * 1981-12-07 1983-06-15 Albert Macovski Energy-selective X-ray recording and readout system
EP0094259A1 (en) * 1982-05-12 1983-11-16 E.I. Du Pont De Nemours And Company X-ray intensifying screens based on phosphor mixtures
EP0160327A1 (en) * 1984-03-05 1985-11-06 Mitsubishi Cable Industries, Ltd. Laminar radiation-shielding article
EP0174875A2 (en) * 1984-09-14 1986-03-19 Konica Corporation Method for converting radiographic image and radiation energy storage panel having stimulable phosphor-containing layer
EP0347171A2 (en) * 1988-06-13 1989-12-20 Konica Corporation Radiation image storage panel

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