EP0121403A2 - X-ray intensifying screens - Google Patents
X-ray intensifying screens Download PDFInfo
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- EP0121403A2 EP0121403A2 EP84302092A EP84302092A EP0121403A2 EP 0121403 A2 EP0121403 A2 EP 0121403A2 EP 84302092 A EP84302092 A EP 84302092A EP 84302092 A EP84302092 A EP 84302092A EP 0121403 A2 EP0121403 A2 EP 0121403A2
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- European Patent Office
- Prior art keywords
- screen
- support
- light absorber
- underlayer
- layer
- Prior art date
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- 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
Definitions
- This invention relates to X-ray intensifying screens used with photographic film elements to record X-ray images thereon, and particularly to screens having improved imaging characteristics. Still more particularly, this invention relates to X-ray screens having controllable speed and to radiographs produced therefrom which exhibit good image sharpness and reduced noise.
- X-ray intensifying screens made by incorporation of.a luminescent phosphor in a binder and coated on a suitable support are well-known in the prior art. These X-ray screens absorb X-rays and emit energy in the form of light, which in turn exposes a photographic film associated therewith.
- the phosphors used in these screens can be generally segregated into three classes: (1) broad band emitters (e.g. CaWO 4 ); (2) narrow band emitters (e.g. BaFCI:Eu); and (3) line emitters (e.g. LaOBr:Tm).
- broad band emitters e.g. CaWO 4
- narrow band emitters e.g. BaFCI:Eu
- line emitters e.g. LaOBr:Tm
- One method of increasing speed is to increase the thickness of the phosphor coating. As speed increases, however, there is usually a decrease in image sharpness and thus a decrease in the amount of medical information that can be generated by this system. Conventionally, the speed of an X-ray screen is reduced by lowering the thickness of the phosphor layer or by adding broad band absorbers (e.g. dyes or pigments) to the X-ray screen structure. Controlling screen speed by these prior art methods yields the desired higher sharpness but also increases the noise and mottle of the finished radiograph prepared therefrom.
- broad band absorbers e.g. dyes or pigments
- Radiographic noise is a grain or mottle pattern which results from the statistical nature of the imaging process.
- a source of noise is the distribution of scintillation efficiencies of the individual phosphor crystals. Those crystals with low efficiency may only contribute minimally to the imaging process while those with high efficiency lead to increased density. The fluctuations in developed density appear as noise.
- radiographic noise should be lowered, and broadening it will increase noise.
- the addition of dyes or pigments to the screen structure effectively broadens the distribution of scintillation efficiencies, thus increasing the noise.
- the X-ray screen structure conventionally consists of a phosphor-containing layer coated on a suitable support. It is also beneficial to use an underlayer (e.g. reflective or absorbing layer) coated between the phosphor and the support and to include a protective overcoat for the phosphor layer.
- an underlayer e.g. reflective or absorbing layer
- the present invention provides an X-ray intensifying screen comprising, in order, (1) a support, (2) optionally an underlayer, (3) an active layer comprising a phosphor exhibiting narrow or line band emission dispersed in a binder, and (4) optionally an overcoat layer, characterized in that at least one of layers (2), (3) and (4) contains an effective amount of a nonfluorescing ultra-violet (UV) light absorber having absorbance maxima at about 400 nm or below.
- UV ultra-violet
- An X-ray screen made according to the invention, used with a photographic film, will produce a sharper image with lower noise and mottle, compared with a screen made without the UV absorber.
- UV light absorbers that exhibit absorbance maxima at about 400 nm or below. All will function within the ambit of this invention. These include the following:
- absorbers can be dissolved in any convenient organic solvent (e.g. acetone) and added either to layer (2), (3) or (4) in amounts which depend on the effect desired and the layer to which they may be added.
- organic solvent e.g. acetone
- Layer (1) is a support.
- a number of elements can be used such as paper or metal foil, e.g., aluminum. It is preferred to use a macromolecular, hydrophobic organic polymer support.
- Suitable polymeric supports include cellulose derivatives, e.g., cellulose acetate, cellulose propionate, cellulose acetate butyrate, and ethyl cellulose; polyethylene, polyvinyl chloride, poly(vinyl chloride covinyl acetate), polyvinylidene chloride, polyvinyl acetate, polyacrylonitrile, polystyrene, and polyisobutylene; and polyesters, e.g., polyethylene terephthalates and homologous polyesters obtainable by the process described in Whinfield et al:, US-A-2,465,319.
- Polyethylene terephthalate films are particularly useful because of their dimensional stability.
- a particularly useful support is biaxially oriented polyethylene terephthalate coated with a subbing layer of vinylidene chloride-methylacrylate-itaconic acid copolymer as described in Alles et al., US-A-2,779,684.
- the thickness of the support may conveniently be anywhere from about 0.0025 in to 0.03 in (0.0064 cm to 0.0762 cm) with 0.01 in (0.0254 cm) being preferred.
- the support may contain or be coated with dyes or finely divided pigments, e.g., titanium oxide, lithopone, magnesium carbonate, aluminum oxide, carbon black, and colored pigments, e.g. tartrazine (C.I. No. 640), Victoria Green W.B. Base (C.I. No. 800), and Nubian Resin Black (C.I. No. 864), as opacifying or light-absorbing agents.
- dyes or finely divided pigments e.g., titanium oxide, lithopone, magnesium carbonate, aluminum oxide, carbon black, and colored pigments, e.g. tartrazine (C.I. No. 640), Victoria Green W.B. Base (C.I. No. 800), and Nubian Resin Black (C.I. No. 864), as opacifying or light-absorbing agents.
- the above mentioned dyes and pigments are particularly useful in reflective layers to vary the light output or block unwanted wavelengths.
- the base support may be metallized to provide reflective action, e.g., the
- a reflective layer comprising anatase grade Ti0 2 , dispersed in chlorosulfonated polyethylene (e.g., Hypalon 20, E. I. du Pont de Nemours and Company, Inc., Wilmington, DE), on the support.
- chlorosulfonated polyethylene e.g., Hypalon 20, E. I. du Pont de Nemours and Company, Inc., Wilmington, DE
- a number of other reflective pigments can also be used in the reflective layer. These include the potassium titanates of Brixner, US-A-3,895,157, among others.
- phosphors which exhibit narrow or line band emission. These include the yttrium tantalates described in Brixner, US-A-4,225,653, especially Y(Nb)Ta0 4 ; lanthanum oxyhalides (especially LaOCl:Bi and LaOBr:Tm), and the barium fluorohalides described in Joiner, US-A-4,076,897 (especially BaFCl:Eu), among others.
- the phosphors are usually milled for several hours in a solvent/binder mixture and coated over the above referenced reflective layer. A number of binders can be used in the active layer (3) of this invention.
- polyvinyl butyral resins it is preferred to use polyvinyl butyral resins but there are a host of suitable polymers used in the prior art that can be used here.
- the polyurethane elastomeric binders are particularly effective because of their adhesion to the conventional supports described above.
- Polyurethanes are, however, subject to degradation by UV light. Many of the conventional phosphors emit substantial amounts of UV light which can further be reflected back into the active layer by the support; so steps must be taken to prevent this degradation (see Martic et al supra).
- a protective overcoat made according to any of the teachings of the prior art may be applied over the phosphor layer.
- These top coats can be cellulose nitrate or acetate or a mixture of resins comprising poly(methylmethacrylate), poly(isobutyl methacrylate), and vinyl chloride/vinyl acetate copolymers as taught by Patten, U S -A-2,907,882.
- An overcoat similar to that described in Brixner et al in U.S. 3,895,157 is particularly efficacious.
- the overcoat layer can be from about 0.0001 in. to 0.005 in. (0.0003 cm. to 0.013 cm.) in thickness.
- An X-ray screen prepared as described above, and in the examples that follow, is eminently useful in medical radiography, for example.
- the addition of the UV light absorber permits one to control the speed of the screen in a predictable fashion.
- these screens when exposed in conjunction with X-ray photographic film, will exhibit excellent image sharpness and, importantly, noise and mottle is reduced. This allows more information to be determined from the image. This is a considerable and surprising finding over the prior art which teaches thickness reduction in the phosphor layer to improve image sharpness with a concurrent rise in noise and mottle.
- the invention provides an X-ray intensifying screen composed of, in order, (1) a film-forming polyester support, (2) an underlayer comprising Ti0 2 dispersed in chlorosulfonated polyethylene, (3) an active layer comprising LaOBr:Tm dispersed in polyvinyl butyral, and (4) an overcoat layer consisting essentially of a fluoroacrylate polymer, whereinat least one of layers (2), (3) and (4) contains an effective amount of a nonfluorescing UV light absorber having absorbance maxima below about 400 nm.
- Three X-ray intensifying screens were made comprising, in order, a support (1), a reflective layer (2), an active phosphor layer (3), and an overcoat layer (4).
- the UV light absorber was placed in layer (4).
- the reflective suspension was prepared by sandmilling a mixture of the following ingredients for about 4 hours:
- the milled suspension was filtered through a filtering medium with an average pore-size of 30 microns.
- the suspension was deaerated and then coated on a sheet of biaxially oriented polyethylene terephthalate film provided with a substratum of vinylidene chloride-methylacrylate-itaconic acid copolymer prepared as described in US-A-2,698,240.
- a reflective layer was obtained which gave a TiO 2 coating weight of about 0.029 g/in 2 (0.0045 g/cm 2 ).
- the phosphor layer was prepared from the following composition, milled for about 12 hours:
- Screen I contained UV light absorber (A)
- Screen II contained UV light absorber (B)
- Screen III contained UV light absorber (C) at the levels shown above.
- a screen was prepared without any UV light absorber.
- UV light absorber to the overcoat layer (4) significantly reduces the mottle produced by the screen, improving the overall image quality of a film exposed thereto.
- a screen was prepared as in Example 1 except that UV light absorber (B) was instead added to the active phosphor layer (3) at a level of 0.12% by weight of the phosphor (LaOBr:Tm). The following results were obtained:
- Example 2 To test the efficiency of this invention when a UV-light absorber was added to the reflective layer, a screen was made as in Example 1 except that UV light absorber (B) was instead added directly to the reflective suspension at a level of 0.18% by weight of the TiO 2 . The following results were obtained:
- a UV light absorber may also be used in conjunction with a light absorbing underlayer.
- an active phosphor suspension (see Example 1) containing 0.53% of UV light absorber ( B ) was coated directly on a polyethylene terephthalate film support which contained sufficient-carbon to yield an optical density greater than 8.0 (opaque base). This simulates the application of an absorbing underlayer (vs. reflective underlayer in the previous examples). The following results were obtained when this screen was used to expose a high speed X-ray film as taught in Example 1:
- the dyed screens Prior art elements
- the screen When coated at a thinner coating weight than the screen of this invention, the dyed screens (prior art elements) were ca. 40% higher in mottle, although somewhat sharper in resolution.
- the screen When dye is added to a screen of comparable thickness, the screen is ca. 20% higher in mottle.
- the screen which embodies this invention can greatly improve the signal/mottle ratio and yield an overall improved image on an X-ray film exposed therewith.
- CaWo 4 is an example of a broad band-emitting phosphor outside the scope of this invention. Three screens were made employing the following structure:
- Example 6 was repeated substituting Ba(Pb)SO 4 (another broad band-emitting phosphor) with the following results:
- the UV light absorber failed to significantly improve the image quality of the film exposed to a screen having the broad band-emitting Ba(Pb)SO 4 phosphor.
- phosphor having a narrow emission band is LaOCl:Bi.
- Two screens having this phosphor were prepared according to the teachings of Example 1. Screen I was prepared without a UV light absorber while Screen II contained 0.52 wt.% of UV light absorber (A) in the overcoat layer. The screens were used to expose high speed medical X-ray film with the following results:
- Example 9 was repeated using BaFCI:Eu (narrow band emitter) as the phosphor and with 1.04 wt. % of UV light absorber (B) in the overcoat layer. The following results were noted:
- Example 10 was repeated using LaOBr:Tb (line emitter) as the phosphor and with 0.52 wt.% of UV light absorber (B) in the overcoat layer. The following results were noted:
Abstract
Description
- This invention relates to X-ray intensifying screens used with photographic film elements to record X-ray images thereon, and particularly to screens having improved imaging characteristics. Still more particularly, this invention relates to X-ray screens having controllable speed and to radiographs produced therefrom which exhibit good image sharpness and reduced noise.
- X-ray intensifying screens made by incorporation of.a luminescent phosphor in a binder and coated on a suitable support are well-known in the prior art. These X-ray screens absorb X-rays and emit energy in the form of light, which in turn exposes a photographic film associated therewith. The phosphors used in these screens can be generally segregated into three classes: (1) broad band emitters (e.g. CaWO4); (2) narrow band emitters (e.g. BaFCI:Eu); and (3) line emitters (e.g. LaOBr:Tm). Conventionally, the X-ray screens made with these phosphors abused with radiographic, silver halide film to record X-ray images. In the field of medical X-ray the use of X-ray screens is particularly useful, since there is a pressing need to reduce patient dosage to potentially harmful X-rays. Screens serve to greatly increase the overall system speed, thus requiring less X-ray output to generate a satisfactory image.
- One method of increasing speed is to increase the thickness of the phosphor coating. As speed increases, however, there is usually a decrease in image sharpness and thus a decrease in the amount of medical information that can be generated by this system. Conventionally, the speed of an X-ray screen is reduced by lowering the thickness of the phosphor layer or by adding broad band absorbers (e.g. dyes or pigments) to the X-ray screen structure. Controlling screen speed by these prior art methods yields the desired higher sharpness but also increases the noise and mottle of the finished radiograph prepared therefrom.
- Radiographic noise is a grain or mottle pattern which results from the statistical nature of the imaging process. A source of noise is the distribution of scintillation efficiencies of the individual phosphor crystals. Those crystals with low efficiency may only contribute minimally to the imaging process while those with high efficiency lead to increased density. The fluctuations in developed density appear as noise. By narrowing the distribution of scintillation efficiencies, radiographic noise should be lowered, and broadening it will increase noise. As discussed above, the addition of dyes or pigments to the screen structure effectively broadens the distribution of scintillation efficiencies, thus increasing the noise.
- The X-ray screen structure conventionally consists of a phosphor-containing layer coated on a suitable support. It is also beneficial to use an underlayer (e.g. reflective or absorbing layer) coated between the phosphor and the support and to include a protective overcoat for the phosphor layer.
- It is an object of this invention to provide an improved X-ray screen prepared with phosphors exhibiting narrow band or line emissions. It is another object of this invention to provide X-ray screens which can be used with photographic film to achieve controlled speed, good image sharpness, and low noise and mottle.
- According to one aspect, the present invention provides an X-ray intensifying screen comprising, in order, (1) a support, (2) optionally an underlayer, (3) an active layer comprising a phosphor exhibiting narrow or line band emission dispersed in a binder, and (4) optionally an overcoat layer, characterized in that at least one of layers (2), (3) and (4) contains an effective amount of a nonfluorescing ultra-violet (UV) light absorber having absorbance maxima at about 400 nm or below. An X-ray screen made according to the invention, used with a photographic film, will produce a sharper image with lower noise and mottle, compared with a screen made without the UV absorber.
- While the use of a UV abosorber in an X-ray screen is not novel per se (see Martic et al, US-A-3,743,833), the use of a UV absorber specifically with narrow or line band phosphor to greatly improve the image quality of these highly efficient materials has not been shown.
-
- These absorbers can be dissolved in any convenient organic solvent (e.g. acetone) and added either to layer (2), (3) or (4) in amounts which depend on the effect desired and the layer to which they may be added.
- Layer (1) is a support. A number of elements can be used such as paper or metal foil, e.g., aluminum. It is preferred to use a macromolecular, hydrophobic organic polymer support. Suitable polymeric supports include cellulose derivatives, e.g., cellulose acetate, cellulose propionate, cellulose acetate butyrate, and ethyl cellulose; polyethylene, polyvinyl chloride, poly(vinyl chloride covinyl acetate), polyvinylidene chloride, polyvinyl acetate, polyacrylonitrile, polystyrene, and polyisobutylene; and polyesters, e.g., polyethylene terephthalates and homologous polyesters obtainable by the process described in Whinfield et al:, US-A-2,465,319. Polyethylene terephthalate films are particularly useful because of their dimensional stability. A particularly useful support is biaxially oriented polyethylene terephthalate coated with a subbing layer of vinylidene chloride-methylacrylate-itaconic acid copolymer as described in Alles et al., US-A-2,779,684. The thickness of the support may conveniently be anywhere from about 0.0025 in to 0.03 in (0.0064 cm to 0.0762 cm) with 0.01 in (0.0254 cm) being preferred.
- The support, moreover, may contain or be coated with dyes or finely divided pigments, e.g., titanium oxide, lithopone, magnesium carbonate, aluminum oxide, carbon black, and colored pigments, e.g. tartrazine (C.I. No. 640), Victoria Green W.B. Base (C.I. No. 800), and Nubian Resin Black (C.I. No. 864), as opacifying or light-absorbing agents. The above mentioned dyes and pigments are particularly useful in reflective layers to vary the light output or block unwanted wavelengths. In addition, the base support may be metallized to provide reflective action, e.g., the polyethylene terephthalate base can be coated with a thin layer of aluminum. It is preferred to apply a reflective layer comprising anatase grade Ti02, dispersed in chlorosulfonated polyethylene (e.g., Hypalon 20, E. I. du Pont de Nemours and Company, Inc., Wilmington, DE), on the support. A number of other reflective pigments can also be used in the reflective layer. These include the potassium titanates of Brixner, US-A-3,895,157, among others.
- There are a host of phosphors which exhibit narrow or line band emission. These include the yttrium tantalates described in Brixner, US-A-4,225,653, especially Y(Nb)Ta04; lanthanum oxyhalides (especially LaOCl:Bi and LaOBr:Tm), and the barium fluorohalides described in Joiner, US-A-4,076,897 (especially BaFCl:Eu), among others. The phosphors are usually milled for several hours in a solvent/binder mixture and coated over the above referenced reflective layer. A number of binders can be used in the active layer (3) of this invention. It is preferred to use polyvinyl butyral resins but there are a host of suitable polymers used in the prior art that can be used here. For example, the polyurethane elastomeric binders are particularly effective because of their adhesion to the conventional supports described above. Polyurethanes are, however, subject to degradation by UV light. Many of the conventional phosphors emit substantial amounts of UV light which can further be reflected back into the active layer by the support; so steps must be taken to prevent this degradation (see Martic et al supra). Hence, it is preferred to use binders other than polyurethanes.
- A protective overcoat made according to any of the teachings of the prior art may be applied over the phosphor layer. These top coats can be cellulose nitrate or acetate or a mixture of resins comprising poly(methylmethacrylate), poly(isobutyl methacrylate), and vinyl chloride/vinyl acetate copolymers as taught by Patten, US-A-2,907,882. An overcoat similar to that described in Brixner et al in U.S. 3,895,157 is particularly efficacious. The overcoat layer can be from about 0.0001 in. to 0.005 in. (0.0003 cm. to 0.013 cm.) in thickness. It is preferred to used the fluoracrylate overcoats of Joiner, USSN 420,486, filed September 20, 1982, a copy of which application is on the European Patent Office file of the present application. A corresponding European Patent Application, No. 83109212.7, was filed on 17 September 1983 and was published as EP........A.
- An X-ray screen prepared as described above, and in the examples that follow, is eminently useful in medical radiography, for example. The addition of the UV light absorber permits one to control the speed of the screen in a predictable fashion. Thus, these screens, when exposed in conjunction with X-ray photographic film, will exhibit excellent image sharpness and, importantly, noise and mottle is reduced. This allows more information to be determined from the image. This is a considerable and surprising finding over the prior art which teaches thickness reduction in the phosphor layer to improve image sharpness with a concurrent rise in noise and mottle.
- In a preferred aspect, the invention provides an X-ray intensifying screen composed of, in order, (1) a film-forming polyester support, (2) an underlayer comprising Ti02 dispersed in chlorosulfonated polyethylene, (3) an active layer comprising LaOBr:Tm dispersed in polyvinyl butyral, and (4) an overcoat layer consisting essentially of a fluoroacrylate polymer, whereinat least one of layers (2), (3) and (4) contains an effective amount of a nonfluorescing UV light absorber having absorbance maxima below about 400 nm.
- The invention will now be illustrated by the the following non-limiting examples.
- Three X-ray intensifying screens were made comprising, in order, a support (1), a reflective layer (2), an active phosphor layer (3), and an overcoat layer (4). In this example, the UV light absorber was placed in layer (4). The reflective suspension was prepared by sandmilling a mixture of the following ingredients for about 4 hours:
- The milled suspension was filtered through a filtering medium with an average pore-size of 30 microns. The suspension was deaerated and then coated on a sheet of biaxially oriented polyethylene terephthalate film provided with a substratum of vinylidene chloride-methylacrylate-itaconic acid copolymer prepared as described in US-A-2,698,240. A reflective layer was obtained which gave a TiO2 coating weight of about 0.029 g/in2 (0.0045 g/cm2).
- After drying this layer at about 70-75°F (21.1-23.9°C), an active phosphor layer was applied on the reflective layer. The phosphor layer was prepared from the following composition, milled for about 12 hours:
-
-
- Three screens were prepared. Screen I contained UV light absorber (A), Screen II contained UV light absorber (B), and Screen III contained UV light absorber (C) at the levels shown above. For control, a screen was prepared without any UV light absorber.
- The above referenced screens were tested by exposure with a high speed medical X-ray film to an X-ray unit at 80 KVp, 2 mAs through a 2 mm aluminum filter. A step wedge and a resolving power target were placed between the X-ray source and the film/screen (in direct contact therewith). Each exposed film was then developed, fixed and washed in a conventional x-ray developing system, and the following results were obtained:
- Thus, it is seen that addition of the UV light absorber to the overcoat layer (4) significantly reduces the mottle produced by the screen, improving the overall image quality of a film exposed thereto.
-
- Obviously the resolution was increased and the mottle significantly reduced when UV light absorber (B) was placed in the phosphor layer (3).
- To test the efficiency of this invention when a UV-light absorber was added to the reflective layer, a screen was made as in Example 1 except that UV light absorber (B) was instead added directly to the reflective suspension at a level of 0.18% by weight of the TiO2. The following results were obtained:
- A UV light absorber may also be used in conjunction with a light absorbing underlayer. To test this effect, an active phosphor suspension (see Example 1) containing 0.53% of UV light absorber (B) was coated directly on a polyethylene terephthalate film support which contained sufficient-carbon to yield an optical density greater than 8.0 (opaque base). This simulates the application of an absorbing underlayer (vs. reflective underlayer in the previous examples). The following results were obtained when this screen was used to expose a high speed X-ray film as taught in Example 1:
- To compare screens prepared according to the teachings of this invention with prior art screens, three screens were made with the following structure:
- support (1) - same as Example 1
- reflective layer (2) - same as Example 1
- phosphor layer (3) - same as Example 1 except for coating weight and additives (see table, below)
- overcoat layer (4) - same as Example I excluding the UV absorber
- In Screen I the phosphor layer was coated at a 0.022. inch (0.056 cm) thickness, and UV light absorber (B) at 0.52 wt.% on the phosphor was added. Screen II contained no additive and was coated at a 0.012 inch (0.030 cm) thickness. Screen III contained 1.7 ml of a 1% solution of solvent Yellow 3 Dye (C.I. No.11160:1), a monazo dye dissolved in acetone. The following results were obtained when these screens were used to expose samples of high speed medical X-ray film as described in Example 1:
- When coated at a thinner coating weight than the screen of this invention, the dyed screens (prior art elements) were ca. 40% higher in mottle, although somewhat sharper in resolution. When dye is added to a screen of comparable thickness, the screen is ca. 20% higher in mottle. Thus, the screen which embodies this invention can greatly improve the signal/mottle ratio and yield an overall improved image on an X-ray film exposed therewith.
- CaWo4 is an example of a broad band-emitting phosphor outside the scope of this invention. Three screens were made employing the following structure:
- The support (1) and reflective layer (2) were the same as described in Example 1. The phosphor layer (3) contained CaWO4 in place of LaOBr:Tm of Example 1. The overcoat layer (4) was the same as Example 1 except for the UV light absorber. Screen I contained no UV light absorber. Screen II contained 0.52 weight % of UV light absorber (B) and Screen III contained 0.52 weight % of UV light absorber (A), based on cellulose acetate.
-
- As can be seen from these results, in comparison with Example 1, for instance, there is no effect on overall image quality when the UV light absorbers are used with broad band-emitting phosphors.
-
- Here too, the UV light absorber failed to significantly improve the image quality of the film exposed to a screen having the broad band-emitting Ba(Pb)SO4 phosphor.
-
- The improvement in image quality is noted here.
- Yet another phosphor having a narrow emission band is LaOCl:Bi. Two screens having this phosphor were prepared according to the teachings of Example 1. Screen I was prepared without a UV light absorber while Screen II contained 0.52 wt.% of UV light absorber (A) in the overcoat layer. The screens were used to expose high speed medical X-ray film with the following results:
-
- The improvement in image quality is noted here.
-
- The improvement in image quality is noted here.
- As can be seen from the preceding examples the use of the UV light absorber within X-ray screens made according to the teachings of this invention, which are limited to those luminescent phosphors that have their primary emission as line or narrow bands, produces an X-ray intensifying screen which has greatly improved imaged characteristics in film used therewith. This was not possible in the prior art which taught that one must reduce the coating weight of the phosphor layer in order to achieve good resolution and subsequently found that the image was noisy. Images produced with the screens of this invention have excellent sharpness and, at the same time, have lower noise.
Claims (11)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US47994183A | 1983-03-29 | 1983-03-29 | |
US479941 | 1983-03-29 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0121403A2 true EP0121403A2 (en) | 1984-10-10 |
EP0121403A3 EP0121403A3 (en) | 1984-11-21 |
EP0121403B1 EP0121403B1 (en) | 1988-11-17 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19840302092 Expired EP0121403B1 (en) | 1983-03-29 | 1984-03-28 | X-ray intensifying screens |
Country Status (3)
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EP (1) | EP0121403B1 (en) |
JP (1) | JPS59183400A (en) |
DE (1) | DE3475240D1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0234532A2 (en) * | 1986-02-24 | 1987-09-02 | E.I. Du Pont De Nemours And Company | X-ray intensifying screen with improved topcoat |
EP0592724A1 (en) * | 1992-09-11 | 1994-04-20 | Agfa-Gevaert N.V. | X-ray-intensifying screens with an improved speed/image quality relationship |
US6413699B1 (en) | 1999-10-11 | 2002-07-02 | Macdermid Graphic Arts, Inc. | UV-absorbing support layers and flexographic printing elements comprising same |
EP1316972A2 (en) * | 2001-12-03 | 2003-06-04 | Agfa-Gevaert | A binderless phosphor screen having a pigmented interlayer |
US6815095B2 (en) | 2001-12-03 | 2004-11-09 | Agfa-Gevaert | Binderless phosphor screen having a pigmented interlayer |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2540370B2 (en) * | 1988-10-20 | 1996-10-02 | 富士写真フイルム株式会社 | Radiation image conversion panel |
JPH0782118B2 (en) * | 1988-11-25 | 1995-09-06 | 富士写真フイルム株式会社 | Radiation image conversion panel |
JP2004138440A (en) * | 2002-10-16 | 2004-05-13 | Konica Minolta Holdings Inc | Radiation image transducer panel |
Citations (3)
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FR2066273A5 (en) * | 1969-10-21 | 1971-08-06 | Eastman Kodak Co | X-ray film contg a fluorescent screen |
FR2066276A5 (en) * | 1969-10-21 | 1971-08-06 | Eastman Kodak Co | |
FR2146271A1 (en) * | 1971-07-16 | 1973-03-02 | Eastman Kodak Co |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4259588A (en) * | 1979-10-31 | 1981-03-31 | Eastman Kodak Company | Green-emitting X-ray intensifying screens |
-
1984
- 1984-03-28 DE DE8484302092T patent/DE3475240D1/en not_active Expired
- 1984-03-28 JP JP5853984A patent/JPS59183400A/en active Granted
- 1984-03-28 EP EP19840302092 patent/EP0121403B1/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2066273A5 (en) * | 1969-10-21 | 1971-08-06 | Eastman Kodak Co | X-ray film contg a fluorescent screen |
FR2066276A5 (en) * | 1969-10-21 | 1971-08-06 | Eastman Kodak Co | |
FR2146271A1 (en) * | 1971-07-16 | 1973-03-02 | Eastman Kodak Co |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0234532A2 (en) * | 1986-02-24 | 1987-09-02 | E.I. Du Pont De Nemours And Company | X-ray intensifying screen with improved topcoat |
EP0234532A3 (en) * | 1986-02-24 | 1988-03-16 | E.I. Du Pont De Nemours And Company | X-ray intensifying screen with improved topcoat |
EP0592724A1 (en) * | 1992-09-11 | 1994-04-20 | Agfa-Gevaert N.V. | X-ray-intensifying screens with an improved speed/image quality relationship |
US6413699B1 (en) | 1999-10-11 | 2002-07-02 | Macdermid Graphic Arts, Inc. | UV-absorbing support layers and flexographic printing elements comprising same |
USRE39835E1 (en) * | 1999-10-11 | 2007-09-11 | Rustom Sam Kanga | UV-absorbing support layers and flexographic printing elements comprising same |
EP1316972A2 (en) * | 2001-12-03 | 2003-06-04 | Agfa-Gevaert | A binderless phosphor screen having a pigmented interlayer |
US6815095B2 (en) | 2001-12-03 | 2004-11-09 | Agfa-Gevaert | Binderless phosphor screen having a pigmented interlayer |
EP1316972A3 (en) * | 2001-12-03 | 2007-03-28 | Agfa-Gevaert | A binderless phosphor screen having a pigmented interlayer |
Also Published As
Publication number | Publication date |
---|---|
EP0121403A3 (en) | 1984-11-21 |
JPS59183400A (en) | 1984-10-18 |
DE3475240D1 (en) | 1988-12-22 |
EP0121403B1 (en) | 1988-11-17 |
JPH0517517B2 (en) | 1993-03-09 |
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