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(11) | EP 0 710 879 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Radiographic product Radiographisches Erzeugnis Produit radiographique |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention concerns silver halide photographic products which are associated with X-ray intensifying screens and used in radiography.
[0002] More precisely, the invention concerns a radiographic system containing at least one layer of spectrally sensitised tabular grain silver halide emulsion and an intensifying screen. The invention makes it possible to use a wide range of spectral sensitisers whilst avoiding the problem of residual colouring, also called "dye stain" in the art, in the areas of low exposure of the radiographic image.
[0003] In radiography, particularly in medical radiography, use is normally made of radiographic systems comprising an intensifying screen and a silver halide photosensitive product.
[0004] The use of intensifying screens makes it possible to reduce the quantity of X-rays required to obtain a radiograph and consequently to reduce the quantity of X-rays absorbed by the patient.
[0005] Intensifying screens must have a maximum emission as close as possible to the sensitivity peak of the silver halide grains making up the radiographic film.
[0006] The silver halide photosensitive products used in radiography with intensifying screens comprise a transparent support coated on one of its faces, and preferably on both faces, with at least one layer of spectrally sensitised silver halide emulsion.
[0007] Silver halide grains are naturally sensitive to blue light, but, by adsorbing spectral sensitising dyes on their surface, they may have maximum absorption in the blue and/or green and/or red regions of the visible spectrum. In practice, the spectral sensitising dye is chosen so that the maximum absorption of the silver halide grains occurs in the region of maximum emission of the intensifying screen.
[0008] For example a screen is used emitting in the blue region between 360 and 500 nm and a spectral sensitising dye in the blue region having maximum absorption in this range.
[0010] For example, US patent 4,639,411 describes a radiographic element which comprises an emulsion consisting of tabular silver halide grains capable of forming a latent image when it is exposed to light. This emulsion preferably consists of tabular grains with a thickness of less than 0.5 µm and an aspect ratio higher than 5:1.
[0011] Tabular grain emulsions require a high level of sensitising dye because of the high specific surface area of the grains. Certain spectral sensitising dyes cause, in the radiographic image, a residual colouring in the areas which are unexposed or only slightly exposed. For example, the image then has yellow colouring in the areas of low density, if the dye is a spectral sensitiser in the blue region. This problem is particularly significant with fast processing which takes place in less than a minute and in which the time of immersion in the processing solution is very short.
[0012] In order to avoid this phenomenon, it is necessary to use a spectral sensitising dye which does not form any residual colouring, which limits the choice thereof. This is illustrated by US-A-5 108 887.
[0013] The invention makes it possible to use spectral sensitising dyes which, if they were used alone in high quantities, would have caused a residual colouring in the areas of the image of low density. According to the invention, this colouring is avoided by associating therewith an optical brightener having special characteristics. One advantage of the invention is that it affords a greater degree of freedom in the choice of spectral sensitising dyes. In addition, surprisingly, the sensitometric properties of the radiographic image are not substantially impaired by the presence of the optical brightener according to the invention.
[0014] The optical brighteners which have been known for a long time are substances which absorb ultraviolet light in the region of the spectrum lying between 300 and 400 nm and which are fluorescent in the blue region of the visible spectrum.
[0015] They are used for improving the whiteness of photographic papers and in photographic films. Research Disclosure of July 1983, No 23136, describes inter alia the use of optical brighteners in radiographic systems.
[0016] According to this article, the presence of optical brighteners reduces the yellow appearance of the supporting polymer when a source of ultraviolet light is used. The optical brightener is incorporated in a layer placed on the support, or on the support by soaking the support in a solution containing the optical brightener, for example a developing or fixing solution or a stabilising bath.
[0017] This article does not deal with the problem of the residual colouring due to the spectral sensitising dye.
[0018] US patent 4,232,112 describes a process for developing a colour photographic film in which the development solution or the bleaching/fixing solution comprises a bleaching agent which is a derivative of 4,4'-diamino-stilbene disulphonic acid and a second compound derived from benzene sulphonic or naphthalene sulphonic acid. This process makes it possible to avoid on the one hand the residual colouring due to oxidation of the color developer in the bleaching/fixing solution and on the other hand the residual colouring which is due to the accumulation of various substances on the edges of the film.
[0019] US patent 4,587,195 describes a method for eliminating the residual colouring in a colour image. For this purpose a development solution is used comprising a combination of optical brighteners of the triazylstilbene type with slightly shifted absorption peaks.
[0020] US patent 5,238,793 describes a method of processing black and white films comprising a layer of silver halide emulsion spectrally sensitised with a cyanine dye. When the rate of replenishment of the processing solution is low or when the level of sensitising dye is high, the spectral sensitising dye forms in the processing solutions solid particles which adhere to the surface of the film and form specks or blotches on the final image.
[0021] In order to avoid this phenomenon, the exposed film is placed in contact with a processing solution comprising a compound enabling the spectral sensitising dye to dissolve. The solubilising compound is a stilbene derivative which is incorporated in the processing solution in which the formation of solid particles poses a problem, but it can also be in the photographic element. This possibility is not put into practice in this patent, which contains no disclosure relating to the location of the solubilising compound in the photographic element.
[0022] The problem of residual colouring resolved by the present invention is quite another matter, since it is due not to an accumulation of solid particles in the processing solution, but to the absorption of the residual spectral sensitising dye in the gelatin of the radiographic product.
[0023] Thus the problem of the residual colouring which occurs in the radiographic image, in particular after fast processing, when the emulsion contains certain spectral sensitising dyes, is not resolved by the prior art and none of the documents cited discloses or suggests the use of optical brighteners for resolving this problem.
[0024] Also one of the objects of the invention is a radiographic product comprising a support and at least one photosensitive layer comprising gelatin, at least one photosensitive silver halide tabular grain emulsion and a spectral sensitising dye in the blue region having an emission peak between 400 and 500 nm and present in the said radiographic product in sufficient quantity to cause, in the radiographic image, the formation of a residual yellow colouring due to the absorption of the aggregate of the residual dye in the gelatin, and an optical brightener
a) which is a derivative of 4,4'-diaminostilbene disulphonic acid having at least 3 anionic sulpho groups,
b) which is put in at least one of the photosensitive layers of the radiographic product or in at least one layer of gelatin located between the photosensitive layer and the support.
[0025] Anionic sulpho group means an ionised -SO3- group associated with a cation balancing the ionic charge by opposition to an acid group -SO3H.
[0026] Another object of the invention is a radiographic system comprising at least one X-ray intensifying screen with maximum emission between 360 and 500 nm and the radiographic product as defined above.
[0027] In the following description, reference will be made to the drawings in which:
- Figure 1 shows the absorption spectrum between 350 and 500 nm for the RP-XOMAT® process, the optical brightener being in the emulsion layer.
- Figure 2 shows the absorption spectrum between 350 and 500 nm for the KRA® process, the optical brightener being in the emulsion layer.
- Figure 3 shows the optical density of the residual colouring at 440 nm for the RP-XOMAT® process, the optical brightener being in the emulsion layer.
- Figure 4 shows the optical density of the residual colouring at 440 nm for the KRA® process, the optical brightener being in the emulsion layer.
- Figure 5 shows the absorption spectrum between 350 and 500 nm for the RP-XOMAT® process, the optical brightener being in a layer of gelatin between the support and the emulsion layer.
- Figure 6 shows the absorption spectrum between 350 and 500 nm for the KRA® process, the optical brightener being in a layer of gelatin between the support and the emulsion layer.
- Figure 7 shows the optical density of the residual colouring at 440 nm for the RP-XOMAT® and KRA® processes, the optical brightener being in a layer of gelatin between the support and the emulsion layer.
- Figure 8 shows the absorption spectrum between 350 and 500 nm for the RP-XOMAT® process, the optical brightener being in an overcoat of gelatin.
[0028] The emulsions used in the invention are emulsions with tabular grains of silver chloride, silver bromide, silver iodide or a mixture of these halides, in a binder.
[0029] The binder is a water-permeable hydrophilic colloid such as gelatin, gelatin derivatives, albumin, a polyvinyl alcohol, polyvinyl polymers, etc.
[0030] The emulsions may be hardened in accordance with one of the methods described in US patent 4,425,266. The hardening agents which may be used are described in Research Disclosure, December 1989, No 308113, Section X.
[0031] In addition to the characteristics specifically described above, the emulsions may comprise other compounds such as anti-fogging agents, stabilisers or anti-static agents. The radiographic film may comprise an overcoat containing matting agents. This overcoat or the sensitive layer may contain plasticisers or lubricants. These compounds were described in Research Disclosure, Vol 184, August 1979, No 18431.
[0032] These silver halide emulsions are preferably chemically sensitised by means of sulphur and/or gold and/or selenium, in accordance with the conventional chemical sensitisation methods described in Research Disclosure, December 1989, No 308119, Section III.
[0033] The emulsions are spectrally sensitised. The conventional spectral sensitisation methods which can be used are described in Research Disclosure, December 1989, No 308119, Section IV.
[0034] The spectral sensitising dyes which can be used in the present invention are the blue spectral dyes which are liable to produce residual colouring, such as for example cyanine or merocyanine dyes. Cyanine dyes are described in Research Disclosure, December 1989, No 308119, Section IV A-C. Cyanine dyes which can be used according to the invention correspond to the formula:
where Z1 and Z2 represent the atoms necessary to complete a substituted or unsubtituted aromatic ring structure ; R7 and R8 each separately represent a substituted or unsubtituted alkyl radical having 1 to 12 carbon atoms, which may be substituted by a halogen, an alkoxy, aryl, aryloxy, sulpho or carboxyl radical; L1, L2 and L3 each separately represent a methine bond, substituted or unsubtituted; X is O, S, Se, -C- or N- and n is 0, 1 or 2.
[0036] The optical brighteners which are used in the present invention must be capable of destroying the aggregate of the residual sensitising dye in the gelatin, which reduces the optical density corresponding to the residual colouring, giving rise to chemical species in which the wavelength of the absorption peak lies in a region of the visible spectrum where the sensitivity of the eye is low, preferably around the wavelengths below 420 nm. In addition, these optical brighteners must have a sufficient number of solubilising groups to be able to be retained in the gelatin in the layers of the photographic product.
[0037] Examples of optical brighteners which can be used in the present invention are compounds of the stilbene type having at least three anionic sulpho groups. For example it is possible to use compounds having the formula:
where
R1, R2, R3 and R4 are each separately chosen from the group
halogen, hydrogen, hydroxy, substituted or unsubstituted alkyl, substituted or unsubstituted
aryl, substituted or unsubstituted alcoxy and sulpho,
R5 and R6 are each separately chosen from amongst hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted aryl,
M is a cation balancing the ionic charge, with the proviso that the compound has at least one solubilising anionic sulpho group on R1, R2, R3 or R4.
[0038] Examples of useful compounds are described in Table I in US patent 5 238 793 already cited. Compounds which are preferred according to the invention are Phorwite® of formula:
and Tinopal® of formula:
[0039] The quantity of optical brightener is determined so that the residual colouring due to the spectral sensitising dye is highly attenuated without the sensitometric or physical properties of the radiographic product being impaired. In particular, it is desired that the photographic sensitivity, the reciprocity failure, the sensitivity to pressure and the keeping during incubation (fog/speed ratio) should not be substantially modified.
[0040] An appropriate quantity of optical brightener is between 0.05 and 2 mg/dm2 and preferably between 0.5 and 1.5 mg/dm2.
[0041] In addition to the radiographic film, radiographic systems generally comprise a pair of X-ray intensifying screens situated on each side of the radiographic film.
[0042] The intensifying screens used in the invention have an emission peak in the blue or ultraviolet region whose wavelength is between 360 and 500 nm.
[0043] The X-ray intensifying screens comprise one or more luminophores in a mixture with a binder. The luminophore particle size is generally between 0.5 and 20 µm and preferably between 1 and 10 µm.
[0044] Examples of luminophores emitting in the blue or ultraviolet region are calcium tungstate CaWO4, lanthane oxybromide LaOBr activated by terbium or thullium, gadolinium oxybromide activated by yttrium or cerium, YTaO4 activated by gadolinium, bismuth, lead, cerium, barium fluorochloride BaFCl activated by europium, gadolinium, lanthanum or yttrium, or barium sulphate activated by europium or strontium.
[0045] Usable binders are chosen from amongst the organic polymers transparent to light radiation and to X-rays, such as vinyl alcohol and o-sulphobenzaldehyde acetal polymers, chlorosulphonated polyethylenes, bisphenol polycarbonates, alkyl acrylate and methacrylate copolymers and polyurethanes. Other binders which can be used within the scope of the invention are described in US patents 2,502,529, 2,887,379, 3,617,285, 3,300,310, 3,300,311 and 3,743 833 and in Research Disclosure, Vol 154, February 1977. The preferred binders are polyurethanes such as Estane®, Permuthane® and Cargill®,
[0046] The X-ray intensifying screens may contain, in addition to the fluorescent layer, a protective layer and a reflective layer.
[0047] The methods of manufacturing screens and radiographic films are described in the above-mentioned Research Disclosure No 18431.
EXAMPLES 1-3
[0049] The films described in Examples 1-3 consist of an Estar® support coated, in the following order, with a layer of tabular grain silver bromide emulsion having a grain equivalent diameter of 2.14 µm and a mean grain thickness of 0.11 µm and an overcoat of gelatin. In Example 2, the film also comprises a layer of gelatin placed between the emulsion layer and the support. The film is hardened by means of bis(vinylsulphonylmethyl) ether, the amount of hardening agent by weight being equal to 2.25% of the total dry gelatin contained in the film. The emulsion is optimally chemically sensitised by means of sulphur (150 mg KSCN per mole of Ag), gold (5.06 mg Na3(S2O3)2Au,2 H2O per mole of Ag) and selenium (0.67 mg KSeCN per mole of Ag). The emulsion is optimally spectrally sensitised with spectral sensitising dye A.
[0050] The samples of film are exposed to blue light simulating the exposure obtained through an intensifying screen.
[0051] The exposed films are then processed using a conventional RP-XOMAT® process in 90 seconds and a fast KRA® process in 45 seconds.
[0052] After processing, the residual colouring levels are measured by spectrophotometry at 440 nm (the wavelength corresponding to the absorption peak of the aggregate of the sensitising dye in the gelatin), the reciprocity failure for an exposure of between 1/50th and 5 seconds, the spectral sensitivity between 300 and 500 nm. In this way it is verified that no loss of sensitivity occurs in the near ultraviolet because of the absorbance of the optical brightener.
[0053] The resistance to pressure is estimated by using a pressure roller simulating mechanical stresses.
Example 1
[0054] In this example, the optical brightener is put in the emulsion layer of the radiographic product.
[0055] A simplified format of radiographic product is used, as described above and comprising a colourless EstarR support, a tabular grain silver bromide emulsion (21 mg Ag/dm2, 2.85 mg/dm2 gelatin, 465 mg of spectral sensitising dye A per mole of Ag), and an overcoat of gelatin (6.88 mg/dm2). 0.6 mg/dm2 of optical brightener (Tinopal® or Phorwite®) is introduced into the emulsion layer either before spectral sensitisation (IF) or immediately after (AF). The products are processed in automatic processors for the RP-XOMAT® and KRA® processes.
[0056] The results are given in Figures 1 and 2, where
- 1-Check represents the control product which does not contain any optical brightener in the emulsion layer,
- 2-Phorwite® IF (or 3-Tinopal® IF) represents the product according to the invention in which the optical brightener has been introduced into the emulsion before the sensitisation, and
- 4-Phorwite® AF (or 5-Tinopal® AF) represents the product according to the invention in which the optical brightener has been introduced into the emulsion after sensitisation.
[0057] Figures 1 and 2 show the absorption spectrum between 350 and 500 nm. The yellow residual dye, due to the aggregate of the sensitising dye retained in the gelatin, corresponds to the principal peak situated at 440 nm. A less prominent peak can be seen, corresponding to the monomeric sensitising dye at around 410 nm.
[0058] In the presence of the optical brightener, a reduction in the height of the peak at 440 nm is observed, and a modification of the spectrum between 420 and 350 nm, which is explained by the destruction of the dye aggregate in the gelatin and the formation of species resulting from the interaction between the optical brightener and the aggregate of the dye in the gelatin.
[0059] Figures 3 and 4 show the optical density of the residual colouring at 440 nm for the RP-XOMAT® and KRA® processes. In these figures, 1-CHECK represents the check sample.
[0060] It can be seen that the method of introducing the optical brightener (before or after the spectral sensitising dye) is not critical.
[0061] In the fast KRA® process, the shortening of the development cycle compared with the RP-XOMAT® process causes an aggravation of the residual colouring in the absence of any optical brightener. The best result for both the KRA® process and the RP-XOMAT® process is obtained with Tinopal®, this improvement being particularly noticeable in the KRA® process.
[0062] In all cases, the presence of an optical brightener in the emulsion layer causes a loss of sensitivity of around 0.03 to 0.06 log H (where H represents the value of the illumination expressed in lux.sec) whilst the other parameters such as the maximum density (Dmax), the minimum density (Dmin) and the contrast are practically unaffected. The reciprocity failure increases, but the sensitivity to pressure and the fog of the products when fresh or after incubation are unchanged.
[0063] The invention makes it possible to eliminate up to 82% of residual colouring in the RP-XOMAT® process and up to 90% of residual colour in the KRA® process without excessively impairing the sensitometric characteristics.
Example 2
[0064] In this example, the optical brightener is located in a layer placed between the emulsion layer and the support. This arrangement may be useful where it is difficult to introduce the optical brightener into the emulsion layer for practical reasons or where interactions with other additives could occur.
[0065] In this example, a simplified format of radiographic product is used, comprising, in the following order, a 20 mg/dm2 gelatin layer between the support and the emulsion layer, a layer of tabular grain silver bromide emulsion (21 mg Ag/dm2, 32 mg/dm2 gel) and an overcoat of gelatin (6.88 mg/dm2). A quantity of optical brightener (Tinopal® or PhorwiteR) of respectively 0.3, 0.6 and 1.2 mg/dm2 is introduced.
[0066] Figures 5 and 6 show the absorption spectrum between 360 and 450 nm. It can be seen that the two compounds make it possible to reduce the residual colouring (lowering of the peak at 440 nm) and are more efficacious in the KRA® process.
[0067] Figure 7 shows the optical density at 440 nm, which corresponds to the residual colouring. CHECK represents the control. The best results are obtained with TinopalR at a concentration of 1.2 mg/m2.
[0068] In all cases, the presence of an optical brightener causes no loss of sensitivity, and the other parameters such as Dmax, Dmin and contrast are practically unaffected. The reciprocity failure, sensitivity to pressure and fog of the product when fresh or after incubation are unchanged.
[0069] The invention makes it possible to eliminate up to 70% of residual colouring in the RP-XOMAT® process and up to 94% of residual colouring in the fast KRA® process without impairing the sensitometric characteristics.
Example 3 (Comparative)
[0070] In this example, a quantity of Phorwite® of 0.4 and 0.6 mg/dm2 respectively is introduced into the gelatin overcoat.
[0072] It can be seen that the effect of the optical brightener is weaker where it is put in the overcoat since it is possible to eliminate only 15% of residual colouring. The sensitometric characteristics are not affected.
[0073] In conclusion, the best compromise enabling the residual colouring to be reduced without for all that modifying the sensitometric characteristics is obtained by putting the optical brightener in the gelatin layer of the photographic product placed between the emulsion layer and the support. In Example 2, 90% of residual colouring is eliminated in the fast KRA® process and 67% of residual colouring in the RP-XOMAT® process with a concentration of Tinopal® of 1.2 mg/m2 without the sensitometric characteristics being affected.
EXAMPLES 4-5
[0074] In these examples, the normal format of radiographic film is used. On both sides of a blue Estar® support, are coated, in the following order, a layer of tabular grain silver bromide emulsion (32 mg/dm2 gel, 21 mg/dm2 Ag), an intermediate layer of gelatin (3.54 mg/dm2 gel) and an overcoat of gelatin (3.54 mg/dm2 gel). In Example 5, the film also comprises a layer of gelatin (14 mg/dm2 gel) placed between the emulsion layer and the support. The film is hardened by means of bis(vinylsulphonylmethyl) ether, the amount of hardening agent by weight being equal to 2.35% of the total dry gelatin contained in the film. The emulsion is chemically sensitised and spectrally sensitised with spectral sensitising dye A as in Example 1.
Example 4
[0076] The samples of film are exposed to blue light by means of a conventional Kodak X-Omat® intensifying screen.
[0077] The exposed films are then processed with an RP-XOMAT® process in 90 seconds and a KRA® process in 45 seconds, as in the previous examples.
[0079] Compared with a control which does not include Tinopal®, a reduction of 70% in the optical density at 440 nm is observed in the RP-XOMAT® process and 86.5% in the KRA® process. A fairly large loss of sensitivity of around 0.08 to 0.1 Log H is also observed and an increase in the reciprocity failure. The other parameters such as Dmax, Dmin and contrast are practically unaffected. The sensitivity to pressure and the fog of the product when fresh or after incubation are unchanged.
Example 5
[0080] In this example, 1.2 mg/dm2 of TinopalR is introduced into the layer of gelatin placed between the support and the emulsion layer.
[0081] The samples of film are exposed and processed using the RP-XOMAT® process in 90 seconds and the KRA® process in 45 seconds, as in the previous example.
[0083] Compared with a control which does not include Tinopal®, a reduction of 80% in the optical density at 440 nm is observed in the RP-XOMAT® process and 93.5% in the KRA® process. Neither loss of sensitivity nor increase in the reciprocity failure are observed. The other parameters such as Dmax, Dmin and contrast are practically unaffected. The sensitivity to pressure and the fog of the product when fresh or after incubation are unchanged.
[0084] In conclusion, as in Examples 1 and 2, the best compromise enabling the residual colouring to be reduced without for all that modifying the sensitometric characteristics is obtained by placing the optical brightener in the gelatin layer of the photographic product placed between the emulsion layer and the support. In Example 5, up to 93.5% of residual colouring is eliminated in the fast KRA® process with a concentration of Tinopal® of 1.2 mg/m2 without the physical and sensitometric characteristics being affected.
1. Radiographic product comprising a support and at least one photosensitive layer comprising
gelatin, at least one photosensitive silver halide tabular grain emulsion and a spectral
sensitising dye of the visible spectrum having an emission peak between 400 and 500
nm and present in the said radiographic product in sufficient quantity to cause, in
the radiographic image, the formation of a residual yellow colouring due to the absorption
of the aggregate of the residual dye in the gelatin, and an optical brightener,
characterised in that the optical brightener
characterised in that the optical brightener
a) is a derivative of 4,4'-diaminostilbene disulphonic acid having at least 3 anionic sulpho groups,
b) is put in at least one of the photosensitive layers of the radiographic product or in at least one layer of gelatin located between the photosensitive layer and the support.
2. Radiographic product according to Claim 1, wherein the optical brightener is in at
least one of the photosensitive layers.
3. Radiographic product according to Claim 1, wherein the optical brightener is in at
least one of the layers of gelatin placed between the photosensitive layer and the
support.
4. Radiographic product according to Claim 1, wherein the optical brightener has the
formula:
where
where
R1, R2, R3 and R4 are each separately chosen from the group
halogen, hydrogen, hydroxy, substituted or unsubtituted alkyl, substituted or unsubstituted
aryl, substituted or unsubstituted alcoxy and sulpho,
R5 and R6 are each separately chosen from amongst hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted aryl,
M is a cation balancing the ionic charge, with the proviso that the compound has at least one solubilising anionic sulpho group on R1, R2, R3 or R4.
5. Radiographic product according to Claim 4, wherein the optical brightener is chosen
from amongst the following compounds:
or
or
6. Radiographic product according to Claim 1, wherein the amount of optical brightener
is between 0.05 and 2 mg/dm2.
7. Radiographic product according to Claim 6, wherein the amount of optical brightener
is between 0.5 and 1.5 mg/dm2.
8. Radiographic product according to Claim 1, wherein the spectral sensitising dye is
a cyanine dye.
9. Radiographic product according to Claim 8, wherein the cyanine dye is chosen from
amongst:
10. Use of the radiographic product according to any one of the preceding claims in a
fast development process, the total processing time of which is less than 1 minute.
11. Radiographic system comprising at least one X-ray intensifying screen, having a maximum
emission between 360 and 500 nm, and the radiographic product according to any one
of Claims 1 to 9.
1. Radiographisches Produkt mit einem Träger und mindestens einer photosensitiven Schicht
mit Gelatine, mindestens einer photosensitiven Silberhalogenid-Tafelkornemulsion und
einem spektral sensibilisierenden Farbstoff des sichtbaren Spektrums mit einer Emissionsspitze
zwischen 400 und 500 nm, der in dem radiographischen Produkt in einer ausreichenden
Menge vorliegt, um in dem radiographischen Bild die Bildung einer restlichen Gelb-Färbung
aufgrund der Absorption des Aggregates des restlichen Farbstoffes in der Gelatine
zu bewirken, und einem optischen Aufheller,
dadurch gekennzeichnet, daß der optische Aufheller
dadurch gekennzeichnet, daß der optische Aufheller
a) ein Derivat der 4,4'-Diaminostilbendisulfonsäure mit mindestens drei anionischen Sulfogruppen ist,
b) in mindestens eine der photosensitiven Schichten des radiographischen Produkts eingeführt ist oder in mindestens eine Schicht aus Gelatine, die zwischen der photosensitiven Schicht und dem Träger angeordnet ist.
2. Radiographisches Produkt nach Anspruch 1, in dem der optische Aufheller in mindestens
einer der photosensitiven Schichten vorliegt.
3. Radiographisches Produkt nach Anspruch 1, in dem der optische Aufheller in mindestens
einer der Schichten aus Gelatine zwischen der photosensitiven Schicht und dem Träger
vorliegt.
4. Radiographisches Produkt nach Anspruch 1, in dem der optische Aufheller die Formel
aufweist:
worin
worin
R1, R2, R3 und R4 jeweils unabhängig voneinander ausgewählt sind aus der Gruppe
Halogen, Wasserstoff, Hydroxy, substituiertem oder unsubstituiertem Alkyl, substituiertem
oder unsubstituiertem Aryl, substituiertem oder unsubstituiertem Alkoxy und Sulfo,
R5 und R6 jeweils unabhängig voneinander ausgewählt sind aus Wasserstoff, substituiertem oder unsubstituiertem Alkyl und substituiertem oder unsubstituiertem Aryl,
M ein Kation ist, das die ionische Ladung ausgleicht, wobei gilt, daß die Verbindung mindestens eine löslichmachende anionische Sulfogruppe an R1, R2, R3 oder R4 aufweist.
5. Radiographisches Produkt nach Anspruch 4, in dem der optische Aufheller ausgewählt
ist aus den folgenden Verbindungen:
oder
oder
6. Radiographisches Produkt nach Anspruch 1, in dem die Menge an optischem Aufheller
zwischen 0,05 und 2 mg/dm2 liegt.
7. Radiographisches Produkt nach Anspruch 6, in dem die Menge an optischem Aufheller
zwischen 0,5 und 1,5 mg/dm2 liegt.
8. Radiographisches Produkt nach Anspruch 1, in dem der spektral sensibilisierende Farbstoff
ein Cyaninfarbstoff ist.
9. Radiographisches Produkt nach Anspruch 8, in dem der Cyaninfarbstoff ausgewählt ist
aus:
10. Verwendung des radiographischen Produktes nach einem der vorstehenden Ansprüche im
Rahmen eines Schnell-Entwicklungsprozesses, wobei die Gesamt-Entwicklungszeit weniger
als 1 Minute beträgt.
11. Radiographisches System mit mindestens einem Röntgenstrahl-Verstärkerschirm mit einer
maximalen Emission zwischen 360 und 500 nm und dem radiographischen Produkt nach einem
der Ansprüche 1 bis 9.
1. Produit radiographique comprenant un support et au moins une couche photosensible
comprenant de la gélatine, au moins une émulsion à grains tabulaires d'halogénures
d'argent photosensibles et un colorant sensibilisateur spectral dans le bleu présentant
un pic d'émission entre 400 et 500 nm et présent dans ledit produit radiographique
en quantité suffisante pour provoquer dans l'image radiographique la formation d'une
coloration résiduelle jaune due à l'absorption de l'agrégat du colorant résiduel dans
la gélatine, et un avivant optique,
caractérisé en ce que l'avivant optique
caractérisé en ce que l'avivant optique
a) est un dérivé de l'acide 4,4'-diaminostilbène disulfonique présentant au moins 3 groupes sulfo anioniques,
b) est placé dans au moins une des couches photosensibles du produit radiographique ou bien dans au moins une couche de gélatine située entre la couche photosensible et le support.
2. Produit radiographique selon la revendication 1 dans lequel l'avivant optique est
dans au moins une des couches photosensibles.
3. Produit radiographique selon la revendication 1 dans lequel l'avivant optique est
dans au moins une des couches de gélatine placées entre la couche photosensible et
le support.
4. Produit radiographique selon l'une quelconque des revendications 1 à 3 dans lequel
l'avivant optique a pour formule:
où
où
R1, R2, R3 et R4 sont chacun séparément choisis dans le groupe
halogène, hydrogène, hydroxy, alkyle substitué ou non, aryle substitué ou non, alcoxy
substitué ou non, et sulfo,
R5 et R6 sont chacun séparément choisis parmi l'hydrogène, alkyle substitué ou non et aryle substitué ou non,
M est un cation équilibrant la charge ionique,
avec la condition que le composé possède au moins un groupe solubilisant sulfo anionique sur R1, R2, R3 ou R4.5. Produit radiographique selon l'une quelconque des revendications 1 à 3 dans lequel
l'avivant optique est choisi parmi les composés suivants :
ou
ou
6. Produit radiographique selon la revendication 1 dans lequel la quantité d'avivant
optique est comprise entre 0,05 et 2 mg/dm2.
7. Produit radiographique selon la revendication 6 dans lequel la quantité d'avivant
optique est comprise entre 0,5 et 1,5 mg/dm2.
8. Produit radiographique selon la revendication 1 dans lequel le colorant sensibilisateur
spectral est un colorant cyanine.
9. Produit radiographique selon la revendication 8 dans lequel le colorant cyanine est
choisi parmi :
10. Utilisation du produit radiographique selon l'une quelconque des revendications précédentes
dans un procédé de développement rapide dont la durée totale du traitement est inférieure
à une minute.
11. Système radiographique comprenant au moins un écran renforçateur de rayons-X, ayant
une émission maximale entre 360 et 500 nm et le produit radiographique selon l'une
quelconque des revendications 1 à 9.