Classifications

• • 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
  • G03C11/00—Auxiliary processes in photography
  • G03C11/02—Marking or applying text
• • 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
  • G21K2004/10—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens with a protective film

Definitions

• This invention relates to a method for permanently marking objects having a hard polymeric surface. It relates especially to a method for marking X-ray screens, direct emitting screens as well as storage phosphor screens.
• a protective layer on the phosphor layer.
• the protective layer protects the phosphor in the phosphor layer from environmental influences, e.g., humidity, vapours etc. and protects the screen against physical damage during use.
• the protective layer is frequently a hard polymeric layer, making the screen almost insensitive to scratches during use and other forms of physical damage.
• Such a protective layer can be produced by applying a polymeric composition on top of the phosphor layer and chemically hardening it, as disclosed in EP-A- 514 146 or in US-A-4 205 116. In many cases a radiation cured protective layer, as disclosed in EP-A-510 754 is applied to the phosphor layer.
• the cleaning solution comprises frequently methylethylketone and ethanol as solvent.
• the producer of the screen wants the screen to be marked so that for each screen the manufacturing history can easily be traced.
• the radiologist wants that the mark of the screen is printed on the film when a radiograph is made with a light sensitive film in contact with the screen, so as to be able to trace at any moment the film/screen pair used to form the radiological image.
• the mark on the screen is easily readable in a dark room, so that when cassettes are manually loaded, it can be checked which screen is present in the cassette at hand. Also official control organisms are demanding a durable marking on X-ray screens.
• the marking on an X-ray screen is not only required for traceability purposes, but in certain radiographic procedures, e.g., in orthopaedics, the X-ray screens that are used comprise marks, e.g. a grid, that make it possible to measure skeletal distances in the radiographs.
• the objects of this invention are realised by providing a method for marking a X-ray screen having phosphor layer and a protective layer on top of it, forming a first surface of said screen, comprising the steps of :
• said dyestuff is image-wise applied on an area of said first surface of said screen, forming an image having dyed and non-dyed areas and both said dyed and non-dyed areas of said image or only said dyed areas are heated.
• X-ray has to be understood as all penetrating radiation and includes i.a. radiation originating from a radioisotope (e.g. a Co60 source), radiation created by an X-ray generator of any type, radiation and high energy particles created by a high energy radiation generator (e.g. Betatron), radiation from a sample labelled with a radioisotope as is the case in e.g. autoradiography.
• a radioisotope e.g. a Co60 source
• an X-ray generator of any type e.g. Betatron
• X-ray screen is used to indicate an intensifying screen, i.e. a supported or self-supporting panel comprising a direct emitting phosphor as well as to indicate a storage screen or photostimulable screen, i.e. a supported or self-supporting panel comprising a storage phosphor or a photostimulable phosphor.
• phosphor is used to indicate a direct emitting phosphor as well as to indicate a storage or photostimulable phosphor.
• diestuff is used to indicate a water or organic solvent soluble dye as well as a pigment.
• mark and the word “image” are in the context of this invention to be understood as a symbol, alphanumeric characters, a picture, a bar code, a combination of the foregoing, etc. In short these words are meant to indicate any permanent means on the X-ray screen that makes it possible to identify a particular screen.
• An X-ray screen can be either self supporting or can comprise a mixture of a phosphor and a binder, coated on a support.
• Typical binders are, e.g., gelatine, polysaccharides such as dextran, gum arabic, and synthetic polymers such as polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate, cellulose acetate butyrate, polyvinyl alcohol, polystyrene, polyester, etc.
• synthetic polymers such as polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate, cellulose acetate butyrate, polyvinyl alcohol, polystyrene
• binders in US-A- 2 502 529, US-A- 2 887 379, US-A-3 617 285, US-A- 3 300 310, US-A- 3 300 311 and US-A- 3 743 833 .
• a mixture of two or more of these binders may be used, e.g., a mixture of polyethyl acrylate and cellulose acetobutyrate.
• Other useful binders in X-ray screens are hydrogenated styrene-diene block copolymers, having a saturated rubber block, as rubbery and/or elastomeric polymers.
• the polymer can be represented by the formula A-B-A (tri-block) or by the formula A-B (di-block), wherein A represents styrene and B represents the hydrogenated diene block e.g. ethylene-butylene or ethylene-propylene.
• A represents styrene
• B represents the hydrogenated diene block e.g. ethylene-butylene or ethylene-propylene.
• binders have been disclosed in, e.g., EP-A- 647 258 and EP-A- 648 254 .
• binders with Tg ⁇ 0 °C and being soluble for at least 5 % wt/wt in ethylacetate can beneficially be used in X-ray screens, as disclosed in EP-A- 758 012 .
• the weight ratio of phosphor to binder is generally within the range of from 50:50 to 99:1, preferably from 80:20 to 99:1, the ratio by volume of phosphor to binding medium is usually more than 70/30 and even more than 85/15.
• the coating weight of the phosphor particles can be adapted to the desired speed of the radiographic screen or panel, but preferably a coating weight between 5 and 250 mg/cm 2 , most preferably between 20 and 175 mg/cm 2 , is used.
• a protective layer On top of the phosphor layer a protective layer is generally applied. This protective layer is mostly in direct contact with the phosphor layer, but this is not necessarily so, thin auxiliary layers (conductive layers, layers containing filter dyes, etc. ) can be present between the phosphor layer and the protective layer.
• Typical protective layers comprise nitrocellulose, ethylcellulose, cellulose acetate or polymethyl(meth)acrylate resin, coated from a solvent.
• a protective layer on top of the phosphor layer is very often made by coating a radiation (Ultra Violet radiation or electron beam radiation) curable solution on top of the phosphor layer and by curing this solution.
• the protective layer that is formed in this way not only protects the phosphor containing layer from mechanical and chemical damage but can be given a relief structure for high ease of manipulation, thereby avoiding sticking, friction and electrostatic attraction while keeping of an excellent image resolution.
• Radiation cured protective layers have been disclosed in, e.g., EP-A- 510 753 and EP-A 510 754 .
• the readability of the mark by a human observer can be maximised and by selecting the dyestuff so as to have an high absorbency for the light emitted by a prompt emitting X-ray screen the impression of the mark on the final radiological image produced while using the screen becomes easy.
• the hue of the dyestuff can be chosen so as to strongly absorb the light that is emitted upon photostimulation. By doing so the hard-copy film can easily be provided by the mark of the screen that was used.
• the general principle of the invention bringing a dyestuff in contact with the surface of an X-ray screen and heating the screen, can be practised in various embodiments.
• thermo-sublimation printing on the surface of the X-ray screen carrying the protective layer by contacting a dye donor material with the surface of the X-ray screen and image-wise heating said donor material could produce a permanent mark or image on the screen.
• a dye donor material e.g. the donor material that is used in a DRYSTAR, - trade name of Agfa-Gevaert NV, Mortsel, Belgium - printer
• a thermal printhead wherein the heating was image-wise modulated
• thermo-sublimation printing is a first embodiment of the general method of this invention : contacting an area of the surface of the X-ray screen with a dyestuff and heating the surface.
• the dyestuff is non-image wise contacted with an area of the surface of the screen and then the dyestuff is heated in accordance with image data.
• the first embodiment of the present invention can also be accomplished by contacting an area of the surface of the screen to an hot-stamping-foil and then hot-stamping the desired information on the screen.
• This again is a method wherein the dyestuff is non-image wise contacted with an area of the surface of the screen and then the dyestuff is heated in accordance with image data. It may be beneficial to treat the area of the surface of the screen that is to be contacted by the hot-stamping-foil first with a corona discharge, producing a very stable mark on the screen.
• the dyestuff is image-wise applied to an area of the surface of the screen and then that area (or if so desired, the whole the screen) is heated.
• aqueous dispersions of pigments can be used to bring the dyestuff on the surface of the screen, it is preferred, in the method according to this invention, to apply the dyestuff from a solution of one or more dyes in an organic solvent to the surface of the X-ray screen, i.e. solvent based inks are preferably used.
• Solvent based inks are, for the method according to this invention, also inks that comprise as solvent less than 50 % by volume of water, the remainder being an organic solvent compatible with water, e.g., lower alcohols (methanol, ethanol, n-propanol and isopropanol), ketones (acetone and methylethylketone), glycols (ethylene glycol, triethyleneglycol), dioxane, etc.
• Typical solvent based inks, that can be used in the method according to the present invention have been disclosed in ,e.g., DE-A- 31 35 800 , WO-A- 97 17409 , EP-A-764 700 and US-A-5 160 535.
• the solution of at least one dye in an organic solvent is preferably applied by ink-jet printing and said solution is preferably a solvent based ink.
• the dyestuff can also be applied to an area of the screen to be marked by electrostatographic methods, using dyed or pigmented toner particles as marking material.
• the toner particles can be applied by lquid development as well as by dry development. The latter development is preferred when the dyestuff is applied to the screen by lectrostatographic methods.
• the dry toner particles are, although any electrostatic method known in the art can be used, preferably applied by a method of direct electrostatic printing wherein toner particles are image-wise projected from a toner source on the screen and wherein no electrostatic latent image intervenes.
• Methods for direct electrostatic printing useful in this invention are methods as described in, e.g., EP-A- 740 224 , EP-A-675 417, EP-A-435 549 , etc..After deposition of the toner particles, the toner particles are fixed to the screen by heating.
• the heating of the dye can proceed by contacting the surface of the screen with an heated body, by contacting the rear surface (i.e. the surface of the screen opposite to the surface whereon a phosphor layer and a protective layer are present) of the X-ray screen with an heated body, the heating can proceed by Infra Red Radiation Lamps, by a laser emitting light in a wavelength range between 480 and 1200 nm, preferably emitting light in a wavelength range between 700 and 1200 nm, e.g., a Nd:YAG laser, a diode laser or a semiconductor laser.
• a typical useful semi-conductor laser is a GaAs-laser emitting around 830 nm, e.g., the GaAs laser sold by Laser Diode Labs, 80 Rose Orchard Way, San Jose, CA, USA under trade name SDL-8110. Also a CO 2 -laser emitting at 10,640 nm is useful in this invention.
• the heating proceeds in non-contact mode by infra red radiation of an infra red lamp or infra red emitting laser. Since the heating proceeds preferably by radiation, it is preferred to use ink-jet inks comprising infra-red absorbing substances or, in the simplest form, black inks.
• a typical useful black ink is the ink sold by the STEADTLER J. S. & Co, of Germany under trade name 48304-9NEU LP29017.
• This embodiment of the invention secures high density printing using ink-jet printing which is a proven method for image-wise applying dyestuffs on a surface.
• the marking with the method according to this invention can proceed on-line, when at the end of the production line of the screen an ink-jet printer is installed followed by an infra red emitter.
• the dyestuff is image-wise applied to an area of the surface of the screen as described in the second embodiment of the invention and then only the image is heated.
• both the application of the dyestuff and the heating proceed image-wise and the image data for addressing the ink-jet printer are also used for addressing the heat source.
• the image-wise application of the dyestuffs can be carried out by the ways and means described above for the second embodiment of the invention.
• the preferred heat source for image-wise heating in this embodiment is an infra red emitting laser, i.e. a laser emitting in a wavelength range from 700 to 1200 nm. It is preferred to use an infra red emitting diode or semiconductor laser.
• a very useful diode laser for use in the second embodiment of the invention is a GaAs diode laser sold by Spectra Diode Labs, 80 Rose Orchard Way, San Jose, CA, USA, under trade name SDL-8110.
• This third embodiment lays in the very local heating of the X-ray screen so that possible damage of the screen due to (excessive) heating is avoided.
• the ink-jet printhead and the diode laser can be built so as to move together so that the written image is heated immediately.
• the dyestuff is non-image-wise applied to an area of the surface of the X-ray screen, then the area covered with the dyestuff is image-wise heated and the dyestuff that not has been heated is removed, thus leaving an image on the X-ray screen.
• the dyestuff can non-image-wise be applied from aqueous dispersions of pigments on said area of the surface of the screen. It is preferred, in the fourth method according to this invention, to apply the dyestuff from a solution of one or more dyes in an solution comprising an organic solvent to the surface of the screen, i.e. with solvent based inks or paint, such as described above under the second embodiment of the invention.
• the non-image-wise application of the dispersion or solution containing a dyestuff on an area of the surface of the X-ray screen can proceed by any means known in the art, e.g., spraying, coating, application by a wick soaked in the solution, etc.
• the image-wise heating can proceed while the area, whereon the dyestuff is applied, is still wet.
• non-contact heating by infra red radiation of an infra red lamp, an infra red emitting laser, an infra red emitting diode or infra red emitting semiconductor laser
• a very useful diode laser for use in the fourth embodiment of the invention is a GaAs sold by Spectra Diode Labs, 80 Rose Orchard Way, San Jose, CA, USA under trade name SDL-8110..
• the area, whereon the dyestuff is applied can also be dried before the image-wise heating. It is then still preferred to use non-contact heating for the image-wise heating, but it is possible, with good results, to use a thermal printhead to perform the image-wise heating as in the first embodiment of this invention.
• the non-heated dyestuff can be removed by simply brushing the remaining dyestuff away, by wiping it away with a solvent, an organic solvent or water, depending on the nature of the solvent used when applying the dyestuff to the surface of the X-ray screen.
• the wiping can proceed by rubbing a cloth soaked in the solvent over the dyed area of the screen, rinsing the screen with the solvent, brushing the solvent over the screen, dissolving the remaining dye, etc.

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• Physics & Mathematics (AREA)
• 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)

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Cited By (2)

Citations (5)

• 1997
  • 1997-10-13 EP EP97203176A patent/EP0908900A1/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (2)

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