EP0370812A2 - Méthode d'atténuation fractionnée d'une radiation électromagnétique - Google Patents

Méthode d'atténuation fractionnée d'une radiation électromagnétique Download PDF

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Publication number
EP0370812A2
EP0370812A2 EP89312178A EP89312178A EP0370812A2 EP 0370812 A2 EP0370812 A2 EP 0370812A2 EP 89312178 A EP89312178 A EP 89312178A EP 89312178 A EP89312178 A EP 89312178A EP 0370812 A2 EP0370812 A2 EP 0370812A2
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EP
European Patent Office
Prior art keywords
group
lead
elements
weight
bismuth
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EP89312178A
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German (de)
English (en)
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EP0370812A3 (fr
Inventor
Georg Peter Reh
Gordon Edward Mawdsley
Martin Joel Yaffe
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811654 ONTARIO INC.
DuPont Canada Inc
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811654 ONTARIO Inc
DuPont Canada Inc
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Publication of EP0370812A2 publication Critical patent/EP0370812A2/fr
Publication of EP0370812A3 publication Critical patent/EP0370812A3/fr
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F1/00—Shielding characterised by the composition of the materials
    • G21F1/02—Selection of uniform shielding materials

Definitions

  • the present invention relates to a method of shielding or protection against electromagnetic radiation, including x-rays and gamma radiation, and to compositions for protection against electromagnetic radiation that are mixtures of two or more radiation-absorbing elements, or compounds thereof, that complement each other over a range of energies.
  • Exposure of matter, including humans, to electromagnetic radiation, especially x-rays or alpha, beta or gamma radiation, from a wide variety of sources is increasing. Such exposure may be deliberate, for example, in the x-raying of a patient or an object, or treatment of a patient with radiotherapy or other radiation emitting devices, but the exposure to radiation may also be an occupational hazard e.g. to the operators of v-ray or other radiation emitting materials or equipment. Many steps are taken to protect workers from exposure to radiation, including the extreme step of completely separating the operator from the radiation source. However, on many occasions such separation is impractical or even impossible.
  • the element is normally selected to reduce or prevent penetration by the highest quantum level of energy in the spectrum, usually the shortest wavelength or highest keV band.
  • Typical methods involve the use of sheet metal, especially metallic lead or lead compounds; lead and its compounds are frequently used for protection against x-rays and beta and gamma radiation.
  • Lead has the advantages of being readily available at low cost and it has a high density and a high atomic number, and is thus a compact absorber of medium to high energy radiation.
  • lead or compounds of lead are finely dispersed in a matrix e.g. an inert, rigid or flexible, polymeric or elastomeric material, or laminated to flexible or reinforced plastics or rubbers, or sintered into refractory lead bricks.
  • a matrix e.g. an inert, rigid or flexible, polymeric or elastomeric material, or laminated to flexible or reinforced plastics or rubbers, or sintered into refractory lead bricks.
  • a matrix e.g. an inert, rigid or flexible, polymeric or elastomeric material, or laminated to flexible or reinforced plastics or rubbers, or sintered into refractory lead bricks.
  • a matrix e.g. an inert, rigid or flexible, polymeric or elastomeric material, or laminated to flexible or reinforced plastics or rubbers, or sintered into refractory lead bricks.
  • Yamamoto published 1982 September 01, discloses a leaded foam material comprising a foamed material having as its base a natural or synthetic rubber.
  • Japanese patent application 61 228 051 of Dainichi Nippon Cables, published 1986 October 11, discloses compositions of ethylene copolymers that contain 5-50 parts of antimony oxide and 5-100 parts of barium sulphate, per 100 parts of polymer, as a wire coating composition that may be cross linked with electrons.
  • U.S. Patent 4 563 494 discloses a polymer composition formed from at least one lanthanide oxide or hydroxide for use as a shield against neutron radiation.
  • U.K Patents 1 603 654 and 1 603 655, granted 1981 November 25, disclose use of compositions of metallic lead in polyvinyl chloride as an x-ray absorption material.
  • additional elements are added in small quantities of from about 5 ppm to less than 5%, as processing aids or as modifiers of the product obtained or to improve the metallurgical properties of lead.
  • processing aids or as modifiers of the product obtained or to improve the metallurgical properties of lead.
  • Such compounds are known in their respective arts as refractory aids, polymer/rubber stabilizers, alloying elements and the like, with the selection of those compounds not being related to any energy absorption properties that the elements may exhibit.
  • UK 2 117 964A of Amersham International published 1983 October 19, discloses a radiation shielding brick formed from a layer of e.g. an alloy of lead that contains 4% of antimony, and a layer of a plastic material.
  • UK 1 137 554 of A. Donath et al (Glasswell Projects), published 1968 December 27, relates to building products formed from a paste or powder of compounds containing lead mixed with an oil or epoxy resin; the lead compound may be a lead oxide or tungstate.
  • UK 984 213 of Egon Rauschert et al, published 1965 February 24, relates to a refractory radiation protection material comprising at least 50% by weight of an inorganic lead compound and at least one inorganic compound of a rare earth metal e.g. a phosphate of cerium or monazite sand; the material is stated to have a higher temperature resistance than lead but only about half the absorption value of lead with respect to hard gamma rays.
  • a rare earth metal e.g. a phosphate of cerium or monazite sand
  • Japanese Kokai 59 126 296 of S. Madao et al, published 1984 July 20, relates to a laminated composition for shielding against radiation, formed from lead or lead compound in a copolymer resin laminated to plasticized polyvinyl chloride.
  • the copolymer may contain roll releasing agents, blocking inhibiting agents and the like, while the polyvinyl chloride is exemplified as containing tin maleate and magnesium oxide.
  • UK 1 122 766 of S. Sedlak published 1968 August 07, discloses a flexible radiation shielding material comprising an elastomeric matrix having filler particles distributed throughout the matrix.
  • the filler is formed from an alloy of an ionization absorbing metal and at least one other metal.
  • the latter is intended to overcome effects of lead compounds e.g. oxides and carbonates, that tend to be naturally present in small amounts in or on metallic lead, for instance as a result of atmospheric pollution, and which act as accelerators for various types of rubber latices; in some instances the same or related compounds are added to rubber latices to promote, catalyse or stabilize reactions e.g. cross-linking or vulcanizing of the rubber.
  • Lead/tin and lead/antimony alloys are disclosed as overcoming such effects.
  • the material is in the form of a body of cement or concrete having a 2.5-35% content of one or more lead, bismuth, tungsten, zirconium, iron, tin, cadmium, lithium or barium compounds of stearic acid and/or a fatty acid, and may be used as shielding against alpha, beta and gamma rays and neutron radiation.
  • Radiation protection materials especially in the form of apparel, are disclosed in the patent application of M.J. Lilley, J.M. MacLeod, G.E. Mawdsley, G.P. Reh and M. J. Yaffe filed concurrently herewith.
  • Highly filled compositions of metal compounds in polymers for use in attenuation of energy are disclosed in the patent application of M.J. Lilley, J.M. macLeod and R.H. Servant also filed concurrently herewith.
  • compositions or protective layers specified herein are on a weight basis, calculated on the amount of primary element e.g. if the compound was barium oxide, then the amount of component would be calculated on the basis of the amount of barium.
  • the present invention provides a method for the protection of matter by fractional attenuation of an electromagnetic radiation spectrum having energies in the range of 10-200 keV, said method comprising providing the matter with a protective layer formed from at least two elements, or compounds thereof, selected from the group consisting of actinium, antimony, barium, bismuth, bromine, cadmium, cerium, cesium, gold, iodine, indium, iridium, lanthanum, lead, mercury, molybdenum, osmium, platinum, pollonium, rhenium, rhodium, silver, strontium, tantalum, tellurium, thallium, thorium, tin, tungsten, uranium and zirconium, each element being in an amount of at least 5% by weight of the layer, said layer consisting of at least 40% by weight of said elements, said elements being selected to have complementary absorption characteristics in at least a selected portion of said spectrum.
  • a protective layer formed from at least two
  • the present invention further provides a material for the protection of matter by fractional attenuation of an electromagnetic radiation spectrum having energies in the range of 10-200 keV, said material comprising a protective layer formed from at least two elements, or compounds thereof, selected from the group consisting of actinium, antimony, barium, bismuth, bromine, cadmium, cerium, cesium, gold, iodine, indium, iridium, lanthanum, lead, mercury, molybdenum, osmium, platinum, pollonium, rhenium, rhodium, silver, strontium, tantalum, tellurium, thallium, thorium, tin, tungsten, uranium and zirconium, each element being in an amount of at least 5% by weight of the layer, said layer consisting of at least 40% by weight of said elements, said elements being selected to have complementary absorption characteristics in at least a selected portion of said spectrum.
  • the protective layer attenuates electromagnetic radiation having energies of greater than 1 keV to an extent that is equivalent to a layer of metallic lead having a thickness of at least 0.10 mm.
  • the protective layer has at least two different elements selected such that at least one element is selected from the group consisting of:
  • the invention is illustrated in the drawing ( Figure 1) in which energy fluence spectra are shown for an unattenuated spectrum, for lead and for a composition of the invention.
  • the present invention relates to a method of protecting matter against the effects of electromagnetic radiation by fractional attenuation of the radiation using a layer of radiation protection material.
  • the invention relates to protection against radiation of at least two different wavelengths, especially in the form of a spectrum of radiation.
  • the combination of elements, or compounds thereof, forming the protective layer will especially depend on the particular spectrum against which protection is required, and particularly the distribution of wavelengths in that spectrum.
  • a preferred protective layer comprises at least one element or compound thereof selected from groups (A), (C) and (D) above with the remainder being at least one element or compound thereof selected from groups (E) or (F), especially 20-70 parts and in particular 30-50 parts from groups (A), (C) and (D), per 100 parts of the protective layer, on an element basis.
  • a preferred protective layer comprises at least one element or compound thereof selected from group (A) above with the remainder being at least one different element or compound thereof selected from groups (B), (C), (E) or (F), especially 50-85 parts and in particular 60-80 parts from group (A), per 100 parts of the protective layer, on an element basis.
  • groups (B), (C), (E) or (F) especially 50-85 parts and in particular 60-80 parts from group (A), per 100 parts of the protective layer, on an element basis.
  • pollonium, actinium, thorium or uranium may be combined with another different element from groups (A), (B) or (C).
  • an element from group (F) may be combined with an element from groups (A), (C) and (D).
  • the protective layer is formed from at least three elements, or compounds thereof.
  • at least one element may be selected from groups (A), (C) and (D), one element from group (E) with the remainder being selected from group(F); preferred amounts of the elements are 20-50 parts per 100 parts of the protective layer, on an element basis.
  • at least one element may be selected from group (A), at least one different element from groups (B) and (C), with the remainder selected from groups (E) and (F); preferred amounts are 20-50 parts per 100 parts of the protective layer, on an element basis.
  • Figure 1 shows the spectral curve for the unattenuated or source radiation (Curve 1) as well as the spectral curve as attenuated by a layer of lead (Curve 2) and by a layer of the lead/barium tungstate composition (Curve 3); Curves 2 and 3 represent 3.2 % transmission of energy. It will be noted that although both the lead and lead/barium tungstate composition result in a substantial amount of attenuation of the radiation, the lead/barium tungstate composition exhibits substantially higher attenuation of radiation in the 70-90 keV range; that range is most often encountered with respect to protection of operators of x-ray equipment.
  • elements may be combined in both type and proportions such that (a) the mass of elements or compounds required to absorb a predetermined fraction of the radiation from a given source may be reduced by up to about 40% by weight compared to a single element e.g. lead, or (b) for the same mass of elements, or compounds thereof, the amount of radiation absorbed is substantially higher than for a single element e.g. by up to 150% of the so-called "lead equivalency".
  • Such properties are particularly important in the field of radiation shielding and protective apparel where better protection or the same protection at less weight of the apparel offers important benefits to the user in terms of protection and/or comfort.
  • the elements are antimony, barium, bismuth, bromine, cadmium, gold, iodine, lanthanum, lead, mercury, molybdenum, rhenium, silver, strontium, tantalum, tellurium, tin, tungsten, uranium and zirconium.
  • the elements may be in the form of elements per se or alloys, amalgams or compounds of such elements.
  • the compounds may in the form of oxides, carbonates, sulphates, halides (especially. bromides, fluorides and iodides), hydroxides, tungstates, carbides, sulphides, uranates and tellurides, or metallic salts of organic acids e.g. acetates, stearates, naphthenates, benzoates, formates, propionates, and other organotin and organolead compounds.
  • the amount of element in the compound should be at least 70% by weight of the compound.
  • the compounds should be compatible with any copolymer, adhesive, carrier or other supporting matrix component of the protective layer in which it is used, although there may be interactions between the components that enhance the properties of the resultant material.
  • Compounds or salts comprising the two, or more, required radiation absorbing elements chemically bonded together are particularly efficient radiation absorbers, per unit mass of the protective layer, since the diluent effect of non-radiation absorbing elements e.g. oxygen, sulphur etc. is avoided.
  • non-radiation absorbing elements e.g. oxygen, sulphur etc.
  • examples include antimony tritelluride, bismuth iodide, mercuric bromide and lead tungstate.
  • metallic alloys or amalgams are also useful, particularly where the element has unwanted impurities, is too reactive or too costly to use in a pure form.
  • the protective layer may be formed in a wide variety of ways e.g. by laminating, adhering or otherwise bonding together layers, including films and foils, formed from each of the components.
  • the components may be admixed and a layer formed from the admixture, especially an admixture that has been melted so that a uniform protective layer has been obtained.
  • Layers may also be obtained by sintering, cladding or depositing e.g. by means of electrodeposition or sublimation techniques, one or more elements onto a substrate or another element.
  • the protective layer will be formed of one or more compounds of the elements, and at least one of the compounds may not be capable of being meltedor fused.
  • the compounds may be admixed with a carrier e.g. a polymer, resin, elastomer or other solid material that is capable of being formed into the protective layer e.g. into films, foils or coatings.
  • a carrier e.g. a polymer, resin, elastomer or other solid material that is capable of being formed into the protective layer e.g. into films, foils or coatings.
  • Such carriers may be thermosetting polymers or thermoplastic polymers, both of which are known in the art, or elastomers, rubbers, waxes, organic adhesives or other binders.
  • the protective layer is produced by sintering or other use of metal powders or admixed with a carrier e.g. a polymer
  • the elements or compounds thereof are used in a finely divided form and are uniformly dispersed throughout the protective layer.
  • the particle size should be less than 100 mesh (screened to an average of less than 150 microns particle size) and in particular have an average of about 200 mesh (screened to greater than 60 microns).
  • the radiation absorbing protective layer of two or more elements is admixed, dispersed, laminated or otherwise mechanically supported by, or with, the use of non-radiation absorbing matter
  • the radiation absorbing component should be at least 50% and preferably at least 65% of the total weight of the protective layer. In preferred embodiments, the radiation absorbing component is at least 80% of the total weight of the protective layer.
  • the protective layer is used in a thickness that attenuates radiation having energies of greater than 10 keV, and is preferably the equivalent of a layer of metallic lead having a thickness of at least 0.10 mm, especially at least 0.25 mm and in particular at least 0.5 mm.
  • equivalency is measured in the manner for determination of lead equivalency known in the art, using for example x-rays having a spectrum energy of, typically, a maximum of 100 kV, as described in Example I.
  • equivalence is determined by measuring the broad area transmission of radiation of a sample of a protective layer for a radiation beam of known energy.
  • the transmission is then measured in the same manner for a set of samples of commercially-pure lead of different known thicknesses, and the equivalence for the test sample is obtained by interpolation.
  • equivalence only applies to the energy spectrum used in the test measurements.
  • a typical energy spectrum is obtained when a potential of 100kVp (KiloVolts Peak) is applied to an x-ray tube.
  • Transmission is defined as the ratio of the exposure (coulombs/kg-air) measured in an ionization chamber with material in the beam to the corresponding exposure obtained without material in the beam.
  • the nature of the protective layer is such that the layers will provide superior attenuation and hence greater protection than lead, or any other single element absorber, per unit mass of element, against radiation having energies of greater than 10 keV, preferably providing protection equivalent to 0.5 mm of lead with less mass of element or better protection at the same mass of element.
  • the improved attenuation applies to a specific energy (wavelength) spectrum, and may be optimized, based on better protection, lower mass and/or lower cost, for each individual energy spectrum or range of spectra.
  • the protective layers of the invention attenuate radiation and provide protection over a broader range of energies of electromagnetic radiation than does metallic lead or lead compounds, or other protective layers based on a single element.
  • the present invention may be used in a variety of manners.
  • the method may be used to protect humans against the effects of x-rays or other radiation e.g. to protect operators of x-ray equipment during treatment of patients or operation of other equipment that emits radiation that is potentially harmful to a human.
  • the method of the present invention may be used to protect other matter e.g. physical objects, against effects of radiation.
  • the method may be used to provide coatings or layers of wrapping material for protection of articles during shipping or use.
  • compositions of metals were prepared and tested for absorption of x-rays. Absorbence to x-rays was measured by the following procedure: Exposure rate was measured using a calibrated ionization chamber at a position 100 cm from a tungsten target x-ray tube collimated to provide a beam measuring 8 cm x 8 cm. The tube was powered by a constant-potential x-ray generator providing 100 kV at 10 mA with a resultant half-value layer (HVL) of 5.0 mm aluminum. Variation in output was less than 0.5%/hour. Samples of the compositions and of lead of known thickness were placed in the beam, 15 cm above the ionization chamber to determine the relative transmissions, and the lead equivalence for the composition was obtained by interpolation.
  • compositions prepared and the results obtained were as follows: Run No. 1 2 3 PbO (wt.%) 27 40 48 SnO (wt.%) 26.5 20 16 BaSO4 (wt.%) 26.5 20 16 Carrier*(wt.%) 20 20 20 Elements in Inorganic Component (wt.%) 80 83 85 Composition Density 3.0 3.1 3.2 Lead Equivalence (mm) 0.38 0.40 0.41 Weight Saving*** 22 17 14 * ethylene.vinyl acetate copolymer, unplasticized ** reduction in weight of sample, elemental basis, compared to lead to give same absorption as 0.5 mm of lead at 100 kVp.
  • a composition of PbO (29.75% by weight) and barium oxide (55.25% by weight) in an ethylene/vinyl acetate copolymer (15% by weight) was prepared.
  • X-ray absorption was measured, for 100 kVp, using the procedure of Example I.
  • the composition weighed 5.9 kg/m2, or 4.54 kg/m2 based on the amount of absorbing elements only.
  • a composition of PbO (22% by weight), tungsten trioxide powder (20% by weight) and barium fluoride (38% by weight) in an ethylene/vinyl acetate copolymer (17% by weight) containing 3% by weight of dioctyl phthalate was prepared.
  • the composition had a density of 3.36 g/cm3.
  • the composition contained 80% by weight of filler and had a flexural modulus of 27.6 MPa.
  • the composition weighed 5.83 kg/m2, or 3.85 kg/m2 based on the amount of absorbing elements only.
  • the elemental weight saving compared to 0.5 mm of lead was 32% and a sample weight saving compared to so-called "lead/vinyl", which has 80% lead in 20% polyvinyl chloride (w/w) and weighs 7.3 kg/m2, of 20%.
  • a composition of lead tungstate (46.75% by weight) and barium fluoride (38.25% by weight) in an unplasticized ethylene/vinyl acetate copolymer (15% by weight) was prepared.
  • the x-ray absorption was measured using the procedure of Example I.
  • the composition weighed 5.9 kg/m2, or 4.31 kg/m2 based on the amount of absorbing elements only.
  • the elemental weight saving compared to 0.5 mm of lead was 24% and the sample weight saving compared to lead/vinyl was 19%.
  • This Example illustrates a composition that does not contain a plasticizer.
  • a composition of metallic lead (21.675% by weight), tungsten trioxide (22.95% by weight) and barium fluoride (40.375% by weight) was prepared in Polymer I (7.50% by weight) and Polymer II (3.75% by weight) was prepared.
  • Polymer I was a blend of stabilized polyvinyl chloride and an ethylene/butyl acrylate/carbon monoxidecopolymer
  • Polymer II was an ethylene/vinyl acetate/carbon monoxide copolymer having a melt index of about 35 dg/min.
  • the composition also contained 3.75% by weight of trioctyl trimellitate. X-ray absorption was measured using the procedure of Example I.
  • the composition weighed 5.48 kg/m2.
  • the elemental weight saving compared to 0.5 mm of lead was 31% and the sample weight saving compared to lead/vinyl was 26%.
  • a composition of barium tungstate (84% by weight) was prepared in a blend of ethylene/vinyl acetate copolymers (9.5% by weight) and Sunthene 4240 processing oil as plasticizer (6.5% by weight).
  • the polymer composition obtained had a density of 3.0 g/cm3. X-ray absorption was measured using the procedure of Example I.
  • the sample of the polymer composition was in the form of sheet having a weight of 4.47 kg/m2.
  • X-ray absorption was measured using the procedure of Example I but at 60 kVp, 80kVp, 100 kVp and 120 kVp. At 100 kVp, the sheet was equivalent to 0.39 mm of lead; the corresponding results at 6okVp, 80 kVp and 120 kVp were 0.27 mm, 0.31 mm and 0.35 mm.
  • a two-layer structure was prepared as follows: one layer was formed from powdered metallic lead in a composition of ethylene/vinyl acetate copolymer containing a plasticizer and a second layer was formed from barium tungstate in the same copolymer and plasticizer. The ratio of lead to barium tungstate in the two layers was 0.70:1 on a weight basis. The layers were placed together, and tested in the manner described herein for the testing of polymer compositions.
  • the sample of the two-layer structure had a weight of 7.32 kg/m2.
  • the absorption of the structure was compared with lead over a range of spectra energies and the lead equivalence was determined.
  • the sheet was equivalent to 0.72 mm of lead; the corresponding results at 60kVp, 80 kVp and 120 kVp were 0.68 mm, 0.63 mm and 0.57 mm.
  • a composition of lead powder (25.3% by weight), barium tungstate (43.1% by weight) and barium iodide (17.9% by weight) in a blend of ethylene/vinyl acetate copolymers (9.6% by weight) and Sunthene 4240 aromatic processing oil (4.1% by weight) was prepared.
  • the polymer composition obtained had a density of 3.47 g/cm3. X-ray absorption was measured using the procedure of Example I.
  • a composition of lead powder (9.0% by weight), a powdered lead/tin (50:50) alloy (35.8% by weight) and barium tungstate (44.6% by weight) in a blend of ethylene/vinyl acetate copolymers (6.3% by weight) and Sunthene 4240 aromatic processing oil (4.3% by weight) was prepared; thus, the composition contained 89.4% by weight of inorganic component.
  • the polymer composition obtained had a density of 4.02 g/cm3. X-ray absorption was measured using the procedure of Example I.
  • a composition of a powdered tin/copper (97:3) alloy (13.8% by weight), a powdered lead/tin (50:50) alloy (50.3% by weight) and tungsten trioxide (25.4% by weight) in a blend of ethylene/vinyl acetate copolymers (6.0% by weight) and Sunthene 4240 aromatic processing oil (4.5% by weight) was prepared; thus, the composition contained 89.5% by weight of inorganic component.
  • the polymer composition obtained had a density of 4.52 g/cm3. X-ray absorption was measured using the procedure of Example I.
  • the elemental weight saving compared to 0.5 mm of lead was 21% by weight and the sample weight saving compared to lead/vinyl was 28% by weight.
  • This example shows the use of two alloys in the composition.
  • compositions were prepared: Component Composition* A B Polymer** I 5.70 9.18 II 2.87 - Plasticizer*** 6.43 5.82 Filler PbO 23.38 23.38 WO3 21.25 21.25 BaF2 40.38 40.38 Density (g/cm3) 3.39 3.39 * amounts are in wt. % ** Polymer I was an ethylene.vinyl acetate copolymer having a vinyl acetate content of 36% and a melt index of 0.8 dg/min. Polymer II was an ethylene/vinyl acetate copolymer having a vinyl acetate content of 33% and a melt index of 25 dg/min, that had been melt grafted with about 1.2% by weight of maleic anhydride. *** The plasticizer was an aromatic processing oil, available as Sunthene 4240 processing oil from Sunoco Inc. of Toronto, Ontario, Canada.
  • compositions A and B were formed by blending the components in a Brabender PlasticorderTM twin rotor mixer at 170°C. Sheets of the compounded composition were then formed by compression moulding, the sheets having a thickness of 1.59 mm.
  • the materials obtained above had an absorbence to x-rays equivalent to 0.58 mm of lead. It was found that the weight equivalent required to provide the absorption exhibited by 0.5 mm of lead was 5.35 kg/m2 for both materials. This represents a weight saving, compared to lead, of 36% but a weight saving compared to so-called "lead-vinyl" of 27%.
  • composition was prepared: Component Composition* C Polymer** I 5.70 II 2.87 Plasticizer*** 6.43 Filler PbO 46.75 BaWO4 38.25 * amounts are in wt. % ** Polymer I was an ethylene.vinyl acetate copolymer having a vinyl acetate content of 36% and a melt index of 0.8 dg/min. Polymer II was an ethylene/vinyl acetate copolymer having a vinyl acetate content of 33% and a melt index of 25 dg/min, that had been melt grafted with about 1.2% by weight of maleic anhydride. *** The plasticizer was an aromatic processing oil, available as Sunthene 4240 processing oil from Sunoco Inc. of Toronto, Ontario, Canada.
  • Composition C was formed by blending the components in a Banbury twin rotor high intensity mixer by feeding the components of the composition to the mixer.
  • the composition obtained was formed into sheets using a calendering process at a processing temperature of about 50-55°C, the sheet having a thickness of 0.81 mm.
  • the sheet was laminated to nylon fabric using the adhesive properties of the polymer mixture at elevated temperature.
  • Example II Additional tests were carried out using the procedure of Example I for the measurement of absorption to x-rays but at 60 kVp, 80 kVp, 100kVp and 120kVp and the lead equivalence was determined. At 100 kVp, the sheet tested was equivalent to 0.12 mm of lead; the corresponding results at 60kVp, 80 kVp and 120 kVp were 0.10 mm, 0.10 mm and 0.12 mm

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EP89312178A 1988-11-25 1989-11-23 Méthode d'atténuation fractionnée d'une radiation électromagnétique Withdrawn EP0370812A3 (fr)

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Application Number Priority Date Filing Date Title
GB8827530A GB2225479A (en) 1988-11-25 1988-11-25 Method of attenuation of electromagnetic radiation
GB8827530 1988-11-25

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EP0370812A2 true EP0370812A2 (fr) 1990-05-30
EP0370812A3 EP0370812A3 (fr) 1990-08-29

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JP (1) JPH02223898A (fr)
CA (1) CA2003878A1 (fr)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2756209A1 (fr) * 1996-11-22 1998-05-29 Massard Rene Procede de coulee de resine, pour la protection in situ de cables enterres
WO1999061710A1 (fr) * 1998-05-26 1999-12-02 Massard Rene Procede de coulee de resine pour la protection in situ de cables enterres
EP1691761A2 (fr) * 2003-12-05 2006-08-23 Bar-Ray Products, Inc. Composition d'attenuation de rayonnements legere, tres mince et souple
US8022116B2 (en) 2003-07-18 2011-09-20 Advanced Shielding Components, Llc Lightweight rigid structural compositions with integral radiation shielding including lead-free structural compositions

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US20070102672A1 (en) 2004-12-06 2007-05-10 Hamilton Judd D Ceramic radiation shielding material and method of preparation
CN101137285B (zh) * 2007-10-12 2010-08-25 魏宗源 用于医用x射线防护的复合屏蔽材料
CN101424615B (zh) * 2008-12-03 2011-10-05 中国科学院上海硅酸盐研究所 一种评估钨酸铅晶体的抗辐照性能的检测方法

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WO1999061710A1 (fr) * 1998-05-26 1999-12-02 Massard Rene Procede de coulee de resine pour la protection in situ de cables enterres
US8022116B2 (en) 2003-07-18 2011-09-20 Advanced Shielding Components, Llc Lightweight rigid structural compositions with integral radiation shielding including lead-free structural compositions
EP1691761A2 (fr) * 2003-12-05 2006-08-23 Bar-Ray Products, Inc. Composition d'attenuation de rayonnements legere, tres mince et souple
EP1691761A4 (fr) * 2003-12-05 2007-10-24 Bar Ray Products Inc Composition d'attenuation de rayonnements legere, tres mince et souple
US7488963B2 (en) 2003-12-05 2009-02-10 Bar-Ray Products, Inc. Flexible polymer sheet filled with heavy metal having a low total weight

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GB8827530D0 (en) 1988-12-29
EP0370812A3 (fr) 1990-08-29
GB2225479A (en) 1990-05-30
CA2003878A1 (fr) 1990-05-25
JPH02223898A (ja) 1990-09-06

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