DE2441784A1 - COMBINATION OF LIGHT SENSITIVE ELEMENTS FOR USE IN RADIOGRAPHY - Google Patents

Description

AGFA-GEVIERT corporation

Combination of light-sensitive elements for the

Twist in radiography.

Priority: Great Britain, September 6, 1973, note no. 41963/73

The invention relates to an improved combination of photosensitive elements used in radiography can be; in particular, it relates to a combination consisting of a fluorescent type X-ray intensifying screen and a silver halide recording element consists.

By the term "radiography" is meant a recording technique that uses penetrating radiation, the high energy radiation like x-rays, gamma rays, beta rays and fast electrons like them can be obtained, for example, in an electron microscope, includes.

It is known that by using intensifying screens in combination with silver halide emulsion materials, the radiation dose can be reduced and that this Combination of an X-ray recording system with high sensitivity offers. A disadvantage of using intensifying screens compared to direct X-ray recording however, is the lower image sharpness, especially when using silver halide materials formed a silver halide emulsion layer on both sides of a support which is transparent to fluorescent light each of which in close contact with one during exposure to X-rays Intensifying screen.

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The light emitted by one of these intensifying screens not only leads to an image-wise blackening in the adjacent silver halide emulsion layer, but it also permeates in a substantial amount the support and gives a blurred image in the silver halide emulsion layer disposed on the opposite side. This phenomenon is called "cross-over". The degree of crossover is determined essentially the image quality of the image contained in the radiographic recording material.

The crossing leads because of the scattering of the light in all directions in the different layers and in the Carrier film of the silver halide recording material and also because of the diffraction and diffuse reflection of light at the interfaces between the layers and the carrier film occur to a blurring.

In British patent specification 821 352 it has already been suggested the influence of the crossover due to the incorporation of filter dyes into the film support and / or the substrate layers or to reduce interlayers of the film. The coloration obtained with these dyes is complementary to the color of the fluorescent light of the intensifying screen used.

In practice this has been achieved by using a blue fluorescent calcium tungstate intensifying screen and a silver halide material contained in its support contains a yellow dye. However, the incorporation of a yellow dye requires the use of a higher one Radiation dose, which because of the relatively weak emissivity of these screens in many Cases exceeds the dose allowed for medical X-ray radiography.

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Another source of the image blurring is the diffuse emission, ie the emission in all directions of the fluorescent light in the material mass of the fluorescent layer as well as the diffuse reflection on the support of the screen Silver halide emulsion material incident fluorescent light rays produce a sharp image, _f therefore, must be non-perpendicularly emitted or reflected. Fluorescence radiation already in the screen material with .Substanzen are weakened, which absorb this radiation. This is of course at the expense of the strength of the vertically directed light, since, however, the oblique radiation has a longer path in the screen material than the vertically emitted or reflected strathluing has the weakening by absorption in the screen material. essential: greater influence on the oblique radiation. ^;

The use of filter dye includes ^: 'of substances, such as screen dyes, in the "conventional screens, such as calcium tungstate screens, limits the use of these screens to" X-ray exposure "with a relatively high degree of evil, so that a large part of the medical X-ray phbtography, in which a low X-ray dose is required for the patient, is not within the possibilities of such screens because of the low emissivity of the phosphor of these screens.

The object of the present invention is to provide a new radiographic combination of an intensifying screen and to provide a silver halide photosensitive element having a visible image with improved resolution can deliver at an even higher sensitivity. One Another object of the invention is to provide a screen-film combination which is particularly well suited for the use in mammography, in which a high image resolution is required.

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Other objects and advantages of the invention will become apparent from the following description and examples.

The above-mentioned objects are achieved according to the invention with a combination of photosensitive Elements suitable for radiography, which is characterized in that it consists of

(1) at least one X-ray fluorescence intensifier screen material, containing a phosphor layer which has a Contains phosphor or a phosphor mixture that (which) consist entirely or mainly of a rare earth metal activated lanthanum oxyhalide, preferably a lanthanum oxychloride or lanthanum oxybromide activated with terbium or with terbium and ytterbium consists, wherein the phosphors can optionally also be activated by cerium and more . than half of the spectral emission of the phosphor or the phosphor mixture above about 4-10 nm, more than half of his (her (her)) spectral emission of visible light between 4-00 and 500 nm and his (her) Emission maximum is in the wavelength range from 400 to 450 nm, the phosphor layer being a coating amount from 200 to 800 g of the lanthanum oxyhalo-

genid phosphor per m and a thickness which is preferably within the range of 60 to 250 μm, the screen material containing one or more dyes and / or pigments that absorb light within the emission spectrum of the phosphor layer, the dyes and / or pigments are preferably present between the phosphor layer and the support of the phosphor layer in an antireflection layer, and the screen material preferably has a gain factor of at least 20 at 40 kV and of at least 25 at 80 kV, and

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(2) a light-sensitive material consisting of a support and at least one silver halide emulsion layer, wherein in the light-sensitive material the combined absorption of the support and the layers on one side of the support is preferably such that (i) the light absorption spectrum thereof is mainly (at least 50%) '%) corresponds to the light emission spectrum of the intensifying screen material in the wavelength range from 400 to 500 nm and (ii) the optical density in the area of overlap of the absorption and emission spectrum resulting therefrom is at least 0.6 due to the self-absorption of the silver halide emulsion layer ( en) and the presence of one or more coloring substances in one or more layers and / or the support of the photosensitive material.

In the radiographic combination of X-ray fluorescence intensifying screens of the present invention, the screens can be arranged separately from the radiation-sensitive silver halide material, or they can form an integrated assembly with the silver halide emulsion so that both the silver halide emulsion and the intensifying screen are provided on one and the same support. The radiographic material can be a single- or double-coated radiographic material, that is to say that the radiographic material comprises a radiation sensitive silver halide emulsion either on only one side or on both sides of the support. The intensifying screens can be provided on either side of a single- or double-coated radiographic material. The radiographic combination of intensifying screens and radiographic materials can furthermore comprise the usual intermediate and / or protective and / or separating layers, which can be arranged between or on the radiation-sensitive emulsion layers and the intensifying screens.

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The lanthanum oxyhalide phosphors give a particularly high emission of fluorescent light when X-rays impinge on them, so that through the use of Fluorescent light-absorbing substances which improve the picture quality, in the intensifying screen, the fluorescent light emission is not reduced to such an extent that low doses are used for medical radiography excluded are.

For use in the field of x-ray photography known as "mammography" is preferably a silver halide material coated on a single side in combination with an intensifying screen, which is in contact with the silver halide emulsion layer is used. In mammography are usually very low kV x-rays, i.e., those within the range of 20 to 40 kV, applied to a Molybdenum or tungsten anode of an X-ray tube. The mammography is in the book "X-ray examination of the Bruöt "by W. Hoeffken and M. Lanyi (1973), Georg Thieme Verlag, Stuttgart, Federal Republic of Germany.

In mammography, screenless film exposures have hitherto mostly been used to achieve high image sharpness. Screenless exposures, or in other words, direct x-ray exposures of the film, require a relatively high silver halide content and a relatively high x-ray dose. By using the phosphors defined above, it is possible to improve the image sharpness of the screen by means of screen dyes to a degree which corresponds to the sharpness obtained with direct X-ray exposures without having to use the high X-ray dose characteristics in direct X-ray photography .

According to the invention used phosphors or fluorescent substances that emit visible light

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Amplifier screens used are, for example, lanthanum oxychloride activated with small amounts of terbium, as described, for example, in British Patent 1 24-7 602. Small amounts of terbium are understood to mean an amount of terbium which is less than 0.006 g atom, based on the lanthanum in the phosphor material,

Preferred lanthanum oxychloride and lanthanum oxybromide phosphors activated with terbium are those of the following general formula

where mean:
X chlorine or bromine,
η 0.006 to 0.0001.

The halogen X is preferably present in an approximately stoichiometric amount, but it can also be less, for example only about 2.5% thereof.

Cerium can replace lanthanum in an amount as described in GB-PS 1 247 602, that is, for example, in an amount of 0.1 to 0.8 mol percent, based on the phosphor .

The preparation of terbium-activated lanthanum oxychloride and lanthanum oxybromide phosphors is described in the aforementioned GB-PS 1 247 602, FR-PS 2 021 398 and 2 021 399 as well as in the published German patent applications 1 952 812 and 2 161 958.

The emission spectrum of a lanthanum oxybromide, which stoichiometric. Mengaa contains oxygen and bromine and which has been activated with 0.002 gramaton of terbium, based on the lanthanum, is in the curve of the attached Fig. 1 shows, in which the relative emission intensity, expressed in percentages (96 I), against the wavelengths,

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expressed in nm. The excitation radiation used was ultraviolet radiation of 313 nm.

Others particularly for use in accordance with the present invention suitable phosphors are disclosed in the German patent application 2 161 958, which corresponds to CA-PS 927 089. These phosphors are terbium- and ytterbium-activated lanthanum oxychlorides or lanthanum oxybromides, which have the following general formula correspond :

where mean:

X chlorine or bromine

w 0.0005 to 0.006 moles per mole of oxyhalide; and y 0.00005 to 0.005 moles per mole of oxyhalide.

The presence of the ytterbium significantly reduces the afterglow effect that follows X-ray exposure, see above that the formation of ghost images is eliminated and sharper images are obtained. The making of this As mentioned above, the class of phosphors was described in the published German patent application 2,161,958. Phosphors in which w is 0.002 are of particular interest for the purposes of the present invention.

Another phosphor composition that can be used in accordance with the invention contains a mixture of a lanthanum oxyhalide phosphor with a yttrium oxysulphide phosphor, both phosphors being activated by terbium. Yttrium oxysulfide phosphors used in blue Emitting range of the visible spectrum are described in DT-AS 1 282 819.

The selected fluorescent substance (s) will be applied in the form of a layer to a carrier or used as a self-supporting layer or film. Suitable Layers or foils have a thickness of preferably

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0.05 to 0.5 mm and contain the fluorescent (η) Substance (s) or luminophores in a binder in an amount dispersed by preferably 80 to 95% by weight. This Binder is, for example, an organic polymer with a high molecular weight. Suitable binders are e.g. cellulose nitrate, Ethyl cellulose, cellulose acetate, polyvinyl acetate, polystyrene, polyvinyl butyral, polymethyl methacrylate and like that.

The ratio of high molecular weight polymer to fluorescent Material generally ranges from 5 to 15 percent by weight. A preferred grain size of the fluorescent substances is preferably in the range from about 1 to 25 pm.

The surface of the layer of fluorescent material can be protected against moisture and mechanical damage by coating an organic high polymer substance which is applied with a thickness of 0.001 to 0.05 nm. Such a protective layer is, for example, a thin film of cellulose nitrate, cellulose acetate, polymethyl methacrylate and the like.

In addition to the fluorescent light impinging perpendicularly on the silver halide layer, there is always a certain amount of diffuse radiation in the intensifying screen which causes image blurring. According to the invention, the sharpness of the image is considerably improved by incorporating a fluorescent light-absorbing dye in the Ver stronger screen material, for example in the fluorescent material . layer, which is also referred to as a reinforcement layer, or in a layer which is called ·. Anti-reflective layer is called. This dye is referred to herein as the umbrella dye. Since the oblique radiation travels a longer path in the screen material, it is weakened to a greater extent by the screen dye or the screen dyes than the perpendicular radiation.

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As used herein, the term "screen dye" includes both dyes (i.e., colored substances in molecular terms subdivided form) as well as pigments.

The anti-reflective layer can be located on the back of the carrier and / or between the reinforcing layer and the carrier; it is applied, for example, directly to the carrier on an adhesive layer of the carrier. In a special case, the screen dye (s) can be incorporated into the support. According to another embodiment, the screen dye is located in a cover layer on the fluorescent layer.

A suitable screen dye used in intensifying screens can be used, which is in the blue area (400 to 500 nm) of the visible spectrum, such as tartrazine (CI. Acid Yellow 23) and an umbrella dye of the structural formula given below

FaO ₃ S- r ^> NaO ₃ S-

HO-C ^ Il H

CH-C C-CH,

are described in U.S. Patent 3,624,229.

The screen dye does not need to come from the intensifying screen material to be removed and therefore any dye or pigment may be used which is present in the Emission spectrum of the fluorescent substance (s) absorbed. So provides a black substance, like soot, which is incorporated into the anti-reflective layer of the Schinn material will have quite satisfactory results.

The screen dye (s) will be preferred in the anti-reflective layer in an amount of at least

0.5.mg / m used. Their use in anti-reflective

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shift within a larger quantity range is by no means restricted. Optical densities of more than 3 can be exceeded. '

Very good results are obtained when used at the same time of screen dye (s) in the underlying anti-reflective layer and in the fluorescent layer Layer containing substances. In this EaIl the Reinforcing layer, for example, the screen dye or the Si'hirm dyes in an amount of 5 mg / m. Possibly becomes the screen dye (s) of the enhancer layer and incorporated into the top layer.

To reduce the cross-over, should at least a layer and / or the support material of the photosensitive material of the invention preferably one Contain dye, hereinafter referred to as "filter dye" denotes the light in the wavelength range as defined by the intensifying screen used in the combination is emitted, absorbed. With the filter dye it can is the same dye as the intensifying screen screen dye, but is preferred removable from the recording material during the treatment. "."

Those in the silver halide emulsion recording material Filter dyes used are preferably the hydrophilic colloid layer between the silver halide emulsion layers or incorporated into the emulsion layers themselves. However, you can also have one or more adhesive layers and even be incorporated into the wearer. As already mentioned, the filter dyes preferably have chemical and / or physical properties such that they are removed or decolorized in one of the treatment baths can be.

According to a preferred embodiment of the present Invention are filter dyes, which in the wavelength

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■ absorb range from about 4-00 to 500 mn, used, if fluorescent screens are used, which essentially emit light in the wavelength range from 400 to .500 nm emit.

The amount of filter color is preferably in the range of amounts which reduce the crossing light to such an extent that its intensity is less than 30 % of the intensity of the light incident on an adjacent emulsion layer. For example, 25 to 1000 mg of filter dye (s) are used per m, but correspondingly higher or lower amounts may be indicated depending on the desired result.

Suitable filter dyes that can be removed from hydrophilic colloid layers are tartrazine and the dyes described in U.S. Patent 3,624,229.

The silver halide of the silver halide emulsion recording material may be in one layer or in one coating, for example in a single coating or in one double or dual coating, i.e. in a material with a silver halide emulsion layer on each Side of a carrier. Suitable carriers are those having properties which allow them to pass through easily through a fast automatic developing device. The carrier should therefore be suitably flexible and preferably transparent, but be able to verify the dimensional accuracy and integrity of the various to maintain coatings on it. Typical film supports are cellulose nitrate, cellulose esters, and polyvinyl acetate Polystyrene, polyethylene terephthalate and the like. Carriers, such as sheets or paper, which are made with α-olefin polymers, in particular with polymers of -olefins which contain two or more carbon atoms, such as polyethylene, polypropylene, ethylene / butene copolymers and the like, coated give good results.

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In the radiographic combination of X-ray intensifying screens and optionally spectrally sensitized silver halide radiographic materials of the invention the screens from the silver halide photosensitive material be arranged separately or they can with the SiI overhalide emulsion layer form an integral unit, so that on one and the same support there is both a SiI-berhalide emulsion layer as well as an X-ray intensifying screen. .

The spectral sensitivity of the silver halide emulsions can be increased or improved according to known methods by spectrally sensitizing in the wavelength range from 400 to 500 nm with customary spectral sensitizing dyes which are used for silver halide emulsions, cyanine and merocyanine dyes as well as other dyes such as those specified by Έ. Λ. Hamer in "The cyanine dyes and related compounds", ■ Interscience Pubiishers (1954), including. These dyes are preferably used in an amount ranging from 20 mg to 20 mg per mole of silver halide.

The silver halide in the emulsion layer or layers can comprise varying amounts of silver chloride, silver iodide, silver bromide, silver chlorobromide, silver bromoiodide and the like, but if it is coated it must be able to produce a negative silver image after exposure and processing, which remains in place, ie in situ. Particularly good Ergebnisse.werden with silver brom jοdidemulsionen obtained in which the average grain size of Silberbromjodidkristalle in the range from about 0.1 lim to about iat. 3 .

If a duplicate silver halide coating is used, the total silver coverage per Qberflächeneinheit (dm) is smaller for both layers than about 0,080 g, and preferably each such layer entB / o less than

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about 0.04 g of silver per dm. As these layers are applied using known methods, it is desirable in the combinations of the present invention that the silver halide (s) stack (s) for less than about 40 ° / o and preferably permeable to less than about 30% of the radiation, which is incident from the screen at wavelengths longer than 410 nm when this silver halide coverage is within the above ranges.

Proper permeability can come in a variety of Methods can be achieved, e.g. by including optically separating barriers, e.g. sub-layers which are between the silver halide-containing layers by changing the composition of these layers Introduction of dyes or other materials, by adjusting the halide balance or by modification the silver halide grain shape, grain size, grain distribution and the same.

The silver halide imaging emulsions can be chemically sensitized by any of the known methods. You can use naturally active gelatin or with small amounts of sulfur-containing compounds such as allyl thiocyanate, Allyl thiourea, sodium thio sulfate, etc. to be matured. You can also with the help of reducing agents sensitized, e.g. with tin compounds, as described in GB-PS 789 823, with polyamines, e.g. diethylenetriamine, and small amounts of precious metal compounds such as gold, platinum, palladium, iridium, Ruthenium and rhodium, as described by R. Koslowsky, Z.Wiss.Phot., 46, (1951), pp.67-72. Typical examples of Precious metal compounds are ammonium chloropalladate, potassium chloroplatinate, Potassium chloroaurate and potassium aurithiocyanate.

Emulsion stabilizers and antifoggants can be added to the silver halide emulsions before or after admixing the Low sensitivity emulsion can be added, e.g.

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the known sulphonic and selenic acids or their salts, aliphatic, aromatic or heterocyclic mercaptan compounds or disulphides, for example those described and claimed in the "known German patent application 2 100 622 , which preferably comprise sulpho or carboxyl groups, mercury compounds, for example those in the BE-PS 524 121, 677 337, 707 386 and 709 195 described, and tetraazaindenes as described by Birr in Z.Wiss.Phot. 47 (1952), pp. 2-58 , for example the hydroxytetraazaindenes of the following general Formula:

OH

RC. C == N
2 V ■

where mean:

R ,. and Rp are each hydrogen, an alkyl, aralkyl or

Aryl radical and
R ₃ . Hydrogen, an alkyl, carboxyl or alkoxy carbonyl radical, such as 5-methyl-7-hydroxy-s-triazole £ 1,5-aJ- pyrimidine.

Other additives can be present in one or more of the hydrophilic colloid layers of the radiation-sensitive silver halide elements of the present invention, for example hardening agents such as formaldehyde, dialdehydes, hydroxyaldehydes, mucochloric and mucobromic acid, acrolein and glyoxal, mordants for anionic color couplers or dyes formed therefrom and coating aids such as saponin, dialkylsulfosuccinic as Natriumdiisooctylsulfo succinate, Alkylarylpolyätherschwefelsäuren, Alkylarylpolyäthyläthersulfonsäuren, carboxyalkylated PoIyathylenglykolather esters, such as they are or described in the FR-PS 1,537,417, such as iso-CGH "-CgH ^ (OCH ₂ CH ₂₎ gOCH ₂ COONa, fluorinated surface-active compounds, as they are, for example, in BE-PS 7 ^ 2 680 and the known German patent applications 1 950 121 and

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1 94-2 665 and inert particles such as Silica, glass, starch and polymethyl methacrylate particles.

In medical radiography it is important that the The time until which the recorded information is available is as short as possible. Therefore should the exposed radiographic silver halide materials within be developed in a minimal amount of time. It is generally known that the development times (treatment times) and in particular the fixing times are shortened can by using silver halide emulsions with a relatively small amount of silver halide per unit area. The use of photographic materials with a low silver halide content However, that implies that the maximum density, contrast and resolution of the image obtained are pretty low. In this context it is interesting to note that fine grain silver halide emulsions have a higher hiding power than coarse-grained emulsions (cf. P. Glafkides, "Photographic Chemistry "Volume I (1958 '), pp. 89-90).

As used herein, "covering power" is the reciprocal of the photographic equivalent of developed silver, i.e. the number of grams

Silver per dm divided by the maximum optical density of the image obtained (silver image density and / or color image density) to understand.

Fine grain emulsions, however, have a lower photographic value Sensitivity to and consequently an exposure is required when using such types of emulsions, which may exceed the allowable dose used in medical X-ray photography. The low one Sensitivity of these fine-grain emulsions with a high hiding power, e.g. of at least 50 »and the low

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Silver halide content, i.e. equivalent to less than

2 2

80 mg silver per dm, e.g. 30 to 80 mg silver per dm, is compensated by the use of the lianthan oxyhalide fluorescent screens, which have a particularly high gain factor.

The term "amplification factor" as used herein is to be understood as a factor that is applied to a previously determined Density D is measured, which indicates the exposure required to produce that density when the film is exposed to X-rays without an intensifying screen, divided by the exposure required to produce the same density, e.g. density D = 1.00, when the film is exposed to the screen, the length distribution being the radiation and the development conditions are kept constant.

In order to speed up the development, the is exposed photographic material preferably in the presence of development accelerators developed. These development accelerators can either be in the silver halide emulsion, in an adjacent layer or layers or in the developer bath. They include alkylene

oxide compounds of various types, for example alkylene oxide condensation products or polymers as in US Pat .340, 991 608 and 1 Ο15 023. Other compounds that accelerate development are onium and polyonium compounds, preferably of the ammonium, phosphonium and sulfonium type, for example trialkylsulfonium salts such as dimethyl-n-nonylsulfonium ptoluenesulfonate, tetraalkylammonium salts such as dodecyltrimethylammonium, alkylpyridinium, alkylpyridinium, and alkylpyridinium-o-toluenesulfonium. such as 1-m-nitrobenzylquinolinium chloride and 1-dodecylpyridinium chloride, bis-alkylene pyridinium salts such as NjN'-tetramethylene-bis-pyridinium chloride, quaternary ammonium and phosphonium polyoxyalkylene salts, especially poly-

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oxyalkylene-bis-pyridinium salts, such as, for example in U.S. Patent No. 2,944,900.

After radiographic exposure, the silver halide radiographic elements of the present invention are developed preferably in a high energy surface developer. The high energy is required for the development to take place quickly to be able to take place and can weaken the developer solution (pH. = 9 to 12) by using a suitable alkali Use of high-energy · developer substances or a combination of developer substances, which as a result of them superadditive effect is very energetic.

The economics of the silver halide in the emulsion can be realized by partially reducing the image density enriched with dyes. This can be done by introducing one or more color couplers into the emulsion, at least in the stage of development with the oxidation product of an aromatic primary amine developing agent, for example of the p-phenylenediamine type, forms one or more dyes, the im absorbs (absorb) the visible part of the spectrum.

Furthermore, it is known that a relatively high maximum density and a relatively high contrast also with a low content of silver halide per unit area can be achieved when putting together a color image can be generated with a silver image, as described, for example, in German Offenlegungsschrift 1,946,652 is.

If color development is used, so-called two-equivalent couplers are preferably used to further reduce the consumption of silver. Thus, only 2 instead of 4 molecules of exposed silver halide are required for the generation of 1 dye molecule. These couplers contain in the coupling position, for example, a halogen atom such as iodine, bromine or chlorine (cf.

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e.g. U.S. Patent 3,006,759). The density of the image is thus obtained by adding the densities of the silver image (s) combined with the dye image (s).

To improve the reproduction of information content, those color couplers of the phenol or <K -naphthol type are particularly suitable which, when the silver halide is color-developed with an aromatic primary amine developer compound, form a quinonimine dye that absorbs mainly in the red area and also in the green area Has absorption maximum in the spectral wavelength range from 550 to 700 (see, for example, the above-mentioned German laid-open specification 1 94-6 652).

Phenolic couplers suitable for this purpose are, for example those of the following general formula

where R. and R ~ each have a carboxylic acid acyl or sulfonic acid acyl group including these groups in the substituted state, for example an aliphatic carboxylic acid acyl, an aromatic carboxylic acid acyl, a heterocyclic carboxylic acid acyl group, for example a 2-furoyl or 2-thienoyl group, a aliphatic sulfonic acid acyl, an aromatic sulfonic acid acyl, a sulfonylthienyl, an aryioxy-substituted aliphatic carboxylic acid acyl, a phenylcarboxylic acid acyl, aliphatic carboxylic acid acyl or a tolylcarboxylic acid acyl group . Such phenolic color couplers and their preparation are described, for example, in US Patents 2,772,162 and 3,222,176 and in British Patent 975,773 .

When color images are made together with silver images, aromatic primary amine dyes are usually used.

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developer compounds, such as Ν, Ν-dialkyl-p-phenylenediamines and derivatives thereof, such as N, N-diethyl-p-phenylenediamine, N-butyl-N-sulfobutyl-p-phenylenediamine, 2-amino-5-diethylaminotoluene hydrochloride, 4- Amino-N-ethyl-N (y3 methanesulfonamidoethyl) -m-toluidine sesquisulfate monohydrate and HydroxyStnyl-N-ethyl-p-phenylenediamine, are used. The color developer can be used together with black-and-white developer compounds such as 1-phenyl-3-pyrazolidinone and p-mono-. methylaminophenol, which is known to have a superadditive effect on color development (cf. LFAMason, "J.Phot.ßci.", I ₁ I (1963), pp. 136-139) and other p-aminophenol derivatives, for example those as described in French patent 1,283,420 describes how 3-methyl-4-hydroxy-N, N-diethylaniline, 3-methyl-4-hydroxy-N-utyl-li-y5-hydroxyethylaniline, 1-methyl-6-hydroxy- 1,2,3,4-tetrahydroquinoline, 1 - / 9 -hydroxyethyl-6-hydro3sy-1,2,3,4-tetrahydroquinoline and N- (4-hydroxy-3 'methylphenyl) pyrrolidine can be used. It is also possible to use combinations of aromatic primary amine color developer compounds in order to achieve an increased color development rate (cf., for example, German patent specification 954 311 and French patent

\ font 1 299 899); Favorable effects are achieved, for example, by using N-ethyl-N-2-hydroxyethyl-pph © nylenediamine together with N-butyl-N-sulfobutyl-p-phenylenediamine, 2 ~ amino-5-diethylaminotoluene hydrochloride or Ν, Ν-difithyl-p- phenylenediamine hydrochloride achieved.

The developer solutions can also contain any of the common susceptible ingredients such as sodium sulfite and Hydroxylamine or derivatives thereof, hardeners, antifoggants, e.g. benzotriazole, 5-nitrobenzimidazole, 5-nitroindazole, Halides, such as potassium bromide, silver halide solvents, coloring and reinforcing compounds, Solvents such as dimethylformamide, dirnethylacetamide and N-methylpyrrolidone for chemical constituents that are involved in the preparation of the developing solutions difficult to solve

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or tend to precipitate when left to stand.

The radiation sensitive emulsions for use in the present invention can be coated on a wide variety of substrates, such as films made of cellulose nitrate, Cellulose esters, polyvinyl acetal, polystyrene, polyethylene terephthalate and other polyester materials as well as papers coated on alpha-olefin, e.g. paper, which is coated with polyethylene or polypropylene.

Preferred carriers comprise a linear condensation polymer for example blue colored polyethylene terephthalate.

Those used in the present recording materials Supports can be coated with sub-layers to allow adhesion of one or more gelatin silver halide emulsion layers to improve on them.

The mechanical strength of melt-extruded carriers polyester type can be improved by stretching. In some cases as described in British Patent 1,234,755 the support may have an adhesive layer on it at the step of stretching.

Suitable subbing layers are those in silver halide photography experienced laughing man known. Regarding the use of hydrophobic film support, reference is made to the composition of adhesive layers as mentioned in the above GB-PS are referenced.

According to this patent, a hydrophobic film support 1) has a layer that is directly attached to this hydrophobic film support adheres and a copolymer of 45 to 99 Sew .-% of at least one of the chlorine-containing monomers vinylidene chloride and vinyl chloride, 0.5 to 10 wt.% of at least an ethylenically unsaturated hydrophilic monomer and 0 to 5 ^, 5 wt .-% of at least one. includes other copolymerizable ethylenically unsaturated monomers, and

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2) a layer in a ratio of 1: 3 to 1: 0.5 parts by weight of a mixture of gelatin and a copolymer of 30 to 70 wt -% comprising butadiene with at least one copolymerizable, ethylenically unsaturated monomers..

The exposed radiographic elements of the present invention are preferably processed in automated processing equipment further processed for X-ray films, in which the photographic materials are automatically and at constant Speed can be brought from one processing unit to another, but those skilled in the art will recognize that the radiographic imaging elements included here also in addition to the above mentioned automatic Processing device can be processed in a variety of methods, such as using the well-known, common manual multitank methods.

With regard to the usual emulsion preparation processes and the use of particular emulsion components, in general referred to the Product Licensing Index of December 1971, in which the following terms in detail explained:

I / II type of emulsion and manufacture of this element

III chemical sensitization

IV Development Modifiers

V Antifoggants and stabilizers

VI Developing Agents

VII hardener

VIII Binders or Polymers for Silver Halide Layers and Other Layers

IX Antistatic Layers

X carrier

XI plasticizers and lubricants

XII coating aids

XV Spectral sensitizers for silver halides XXIII. Coloring ingredients

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XVI absorbent and filter dyes, XXI physical developer systems, and XVIII ^ Additives and coating procedures

The following examples are intended to explain the invention in more detail.

example 1

A color radiographic material was prepared as follows :

To 155 g of a silver bromide iodide emulsion having high sensitivity (9 mol% silver iodide), the 15.5 g gelatin and one contained an amount of silver halide equivalent to 23.9 silver nitrate and an average silver halide grain size of 800 mn, 200 g of a silver chloride emulsion having a low sensitivity containing 16.8 g of gelatin and an amount of silver chloride equivalent to 24 g of silver nitrate contained, admitted.

The low sensitivity silver chloride emulsion was prepared by mixing an aqueous silver nitrate solution into an aqueous gelatin / sodium chloride solution, precipitating the gelatin emulsion with ammonium sulfate, washing, and peptizing. Gelatin and 5-methyl-7-hydroxy-s-triazole 1,5-a3pyrimidine were then added so that no chemical ripening occurred. The mean grain grö'sse, the silver chloride emulsion was 220 nm, the mixture was melted by heating 1-stundiges at 38 ⁰ C, after which were added.:

(a) 14.5 g of a color coupler of the following formula:

H ₅ C- (CH ₂ ) ^ g-

CH ₂ COOH

in the form of an aqueous alkaline solution, GV.705 - 23 -

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(b) an amount of an aqueous acetic acid solution sufficient to neutralize the emulsion (pH 7),

(c) 5-Methyl-7-hydroxy-s-triazolo £ i, 5-a3pyrimidin als.Emulsionetabilisierungs,

(d) saponin as a coating aid and

(e) Mucochloric acid as a hardener.

The emulsion was diluted to make 920 ml and then applied to both sides of an adhered polyethylene terephthalate backing applied in the form of a layer,

2 2 whose total surface area was 10 m (2 χ 5 ι). Both of them A protective gelatin layer 0.0015 mm thick was applied to the sides, after which the radiographic Color material has been dried.

The material so produced was placed between two fluorescence intensifying screens arranged, the lanthanum oxybromide (0.002 g-atoms Terbium, based on the lanthanum) and stoichiometric amounts contained in oxygen and bromine. The fluorescent shell the amplifier screen contained 500 g of the in Cellulose nitrate as a binder dispersed lanthanum oxybromida. The weight ratio of phosphor to binder was 92.5! 7t5 * Iu each screen was between the Luminous layer and the paper carrier film of the screen material , an anti-reflective layer arranged. The anti

2
The reflection layer contained 4 g of carbon black per m 2, dispersed in cellulose nitrate. The weight ratio of carbon black to binder was 10:90.

The radiographic combination of the screen materials and the silver halide material became an 80 kV peak x-ray exposure exposed that passed 6 mm thick aluminum and a test original which is a lead grating test object was about the relationship between sensitivity and modulation transfer function value (MÜF value) to be determined.

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After removal of the intensifying screens the radiographic color material was automatically färbentwickelt, said method comprised a Färbentwicklung (24 seconds at 41 ⁰ C), a fixing (20 seconds at 41 ° C), a water rinse (25 seconds at 41 ⁰ C) and then drying (20 seconds at 55 ° C) The developer bath used had a pH of 10.6 and it contained per liter:

8 g of N-hydroxyethyl-N-ethyl-p-phenylenediamine, 1.5 B hydroxylamine,
4 g anhydrous sodium sulfite,

1 g potassium bromide and. '

65 g anhydrous potassium carbonate. .

The fixation was carried out using a sodium thiosulfate fixing solution. The relationship between the MTF value and the sensitivity was measured using a microdensitometer. It was found that in the combined use according to the invention of the intensifying screens specified above with the radiographic color material a cheaper one Relationship between the MTF value and the sensitivity was obtained as when the same was used in combination radiographic color material with standard calcium tungstate intensifying screens, i.e. a sensitivity was achieved which was four times as high for the same MTF value.

Example 2

A silver bromide iodide X-ray emulsion (1.5 mol% silver iodide) was prepared to contain silver halide grains having an average grain size of 0.60 around and per kilogram 74 g of gelatin and one 190 g of silver nitrate contained corresponding amount of silver halide. The emulsion contained 545 g per kilogram as stabilizers 5-methyl-7-hydroxy-s-triazole 1,5-a [$ pyrimidine, 6.5 g i-phenyl-5-mercaptotetrazole and 0.45. g mercury cyanide. The hiding power achievable with this emulsion was 60.

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The emulsion thus obtained became double-sided on both sides polyethylene terephthalate carrier provided with an adhesive layer applied in such a way that on each side of the support a silver halide emulsion layer

which contained an amount of silver halide equivalent to 6 g of silver nitrate per square meter. Each emulsion layer was coated with a gelatin protective layer in a Beschichtungsatärke corresponding to 1 g / mf ¹ coated.

The material thus produced was placed between the same two fluorescence intensifying screens as used in Example 1 and the resulting radiographic combination was passed through a lead grating test object exposed to 60 kV X-ray radiation, about the sensitivity and the modulation transfer function value to determine.

After removing the intensifying screens, the radiographic materials were processed in a 90 second automatic processor. Development lasted 23 seconds at 35 ^° C. in the Agfa-Gevaert hardening developer G 138, which contains hydroquinone and 1-phenyl-3-pyrazolidinone as developer compounds and glutaraldehyde as hardener. It was found that through the combined use of the intensifying screens specified above with the radiographic silver halide material specified above, a more favorable relationship between the MttF value and the sensitivity was achieved than with the combined use of the same radiographic element with customary calcium tungsten screens, that is, the sensitivity obtained was four times as high as that obtained at the same Μϋϊ-Vert.

Example 3

A sirber bromide iodide X-ray emulsion (1.5 mol% Silver iodide) analogous to that of Example 2, but this time with silver halide grains

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an average grain size of 0.65 pa . The hiding power achievable with this emulsion under the developing conditions defined below was 60. It was then applied to a support and, as described in Example 2 , coated with a protective layer.

composition of the fluorescent screen material I

The fluorescent screen used according to the invention was manufactured as follows:

92.2 g LaOBr: 0.002 Tb: 0.0005 Yb phosphor particles, heirge- * produced according to the method described in the known German patent registration 2 161 958 , were in a solution of 7.8 g Elvacite 2044 (trade name of du Pont de Nemours, Wilmington, Delaware, USA for a high molecular weight poly (n-butyl methacrylate ) dispersed in 21.7 g of toluene.

The dispersion obtained was filtered through a filter with openings with an average diameter of 75 P ¹ and deaerated by exposing it to a pressure of 100 mbar (100 cm water column) .

The average grain size of the phosphor particles was 5 μm. The solids content of the dispersion obtained was 82.1% by weight. The dispersion was applied in the form of a layer on an anti-reflective layer which was applied to an adhesive layered polyethylene terephthalate resin support having a thickness of 250 µm. The adhesive layer was produced from a latex based on a copolymer of vinyl chloride, vinylidene chloride, n-butyl acrylate and itaconic acid (weight ratio 63: 30: 5: 2).

ο The anti-reflective layer contained 4 g of euss per m, dispersed in cellulose nitrate. The weight ratio of carbon black to the binder was 10: ^{0 (} X). The application of the phosphor dispersion in the form of a layer was carried out in the manner

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• Af

ρ carried out that there are 35 mg of phosphor per cm.

Composition of the fluorescent screen material II

Calcium tungstate phosphor screen particles of a commercially available Type (manufactured by the company Riedel-de Haen, Seelze (Hanover), Federal Republic of Germany), as in CaWO ^ - Screens used were made of an intensifying screen make coat, such as those used for the fluorescent screen material I has been incorporated. The phosphor layer was coated in the same phosphor coating amount

ο
per m, as described for the screen material I, applied to the anti-reflective layer given above.

exposure

The light-sensitive material was exposed to 80 kV X-rays, which were filtered through a 6 mm thick aluminum plate and modulated with a test object consisting of a line grid made of lead, in which the width of the bars of the grid becomes gradually smaller and their spatial frequency (number per mm) increases gradually from one side of the test object to the other. By using such a test object during exposure, it is possible to obtain an objective value for sharpness, regardless of the contrast of the subject, by determining the square wave response function (SWBF ¹ '- see Amor. J. Rb 'ntgenol. 106 (1969), pp. 650-65'.

In each case a first and a swelled strip of light-sensitive materials, hereinafter referred to as material A and B, respectively, were placed between two intensifying screen materials I bew. Two amplifier shield materials II in contact with arranged on the opposite sides of the photosensitive material.

The exposed materials were processed in a 90 second automatic processor, wherein the development in 23 seconds at 35 ° C in a hardening

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developer (trade name G 138 Agfa-Gevaert), containing Hydroquinone and i-phenyl-3-pyrazolidinone as developers and glutaraldehyde as a hardener.

The SWEP of the test material was derived from the measurements obtained by scanning the line pattern obtained in these materials with a microdensitometer.

The relative square wave response factor (value of the function) at a spatial frequency of one pair of lines per mm is for the various combinations of light-sensitive materials and screens as defined above are listed in the following table:

Table I. sensitivity SWRF value at 2 pairs of lines
per mm Example 4 S-5-lqg ₁₀ E for
Density = 1.00 1 line pair
per mm 0.45
0.43. combination of 3.57
3.09 0.71
0.70 light sensitive
Material and screen A, I
B, II

A silver bromide iodide X-ray emulsion (1.5 mol- # silver iodide) was prepared to contain silver halide grains having an average grain size of 0.70 pm. The emulsion contained a stabilizer as defined in Example 3, and it was only on one side of an adhered polyethylene terephthalate film base applied, which had a conventional anti-reflective layer on its back. The application the emulsion was carried out in such a way that

an amount of silver halide equivalent to 8 g of silver nitrate per m was applied. The silver halide photographic material thus obtained was used in mammography used and for this purpose © ß was exposed to X-rays, while it is with the fluorescent screen layer one

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-Jo.

Was intensifying screen material in contact, the amplifier layer in ELVAOIOJE 2044 (trade name) as Binder the lanthanum oxybromide phosphor according to the example 3 in a coating amount corresponding to 250 g / m and as umbrella dye "ZAPON REAL YELLOW CGG" (CI. 18 820) in an amount of 0.0379% by weight based on the phosphor, incorporated. The average grain size of the phosphor particles was 2.5 lim

As described in Example 3, the intensifying screen layer was applied to an anti-reflective layer which was applied to a polyethylene terephthalate carrier provided with an adhesive layer had been applied. When X-ray exposure for the Use in mammography was called "SENOGRAPH" (commercial product of the Pa. Compagnie Generale de Radiologie, branch of the Thomson-Brandt group, France). The X-ray tube was operated at 30 kV and the x-rays were taken with a 30 µm molybdenum plate and a 30 mm x polymethyl methacrylate plate filtered.

Compared to direct (umbrella-less) X-ray mammography, those with a film having a higher silver halide content with a silver halide coating amount correspondingly

2
36 g of silver nitrate per m works, the inventive screen-film combination provided 5 times the sensitivity with a higher image contrast. When using a developer as described in Example 3, the development time to achieve the same maximum density with the screen-film combination according to the invention was only 1/15 of the development time required for this film with a high silver halide content.

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Claims (1)

Claims Combination of photosensitive materials suitable for radiography, characterized in that it consists of (1) at least one biofluorescence intensifier screen material, holding a phosphor layer that contains a phosphor or a phosphor mixture which (which) consists entirely or mainly of one lanthanum oxyhalide activated with a rare earth metal, the phosphors or the phosphor mixture has more than half of its spectral emission above about 410. nm, more than half of its (its) spectral emission of visible light between 400 and 500 nm and its (their) emission maximum lies in the wavelength range from 400 to 450 nm, where the phosphor layer has a coverage of 200 to 800 g of the lanthanum oxyhalide phosphor per m and the screen material one or more colorants and / or contains pigments which light within the emission spectrum of the phosphor layer absorb, and (2) a silver halide photosensitive material, consisting of a support and at least one silver halide emulsion layer. 2. Combination according to claim 1, characterized in that the X-ray fluorescence intensifier screen material is such an amount the one or more dyes and / or pigments and the phosphors that contains the gain factor of the screen is at least 20 at 40 kV and at least 25 at 80 kV. 3 " Combination according to claim 1 or 2, characterized in that the combined absorption of the carrier and the layers on one in the silver halide absorption material GV.705 -31- 50S81 1/1 U7 2U1784 Side of the wearer is such that (i) the light absorption spectrum thereof mainly (at least 50%) with the Light emission spectrum of the fluorescence amplifier screen material coincides in the wavelength range of 400 to 300 nm and (ii) the optical density in the range the resulting overlap of the absorption and emission spectrum is at least 0.6 the self-absorption of the silver halide emulsion layer (s). and the presence of one or more coloring substances in one or more layers and / or the support of the silver halide light-sensitive material. 4. Combination according to claims 1-5 »characterized in that that the screen is one or more lanthanum oxybromides as a phosphor or oxychlorides activated by terbium and ytterbium. Combination according to claims 1-4, characterized in that the screen contains one or more terbium-activated lanthanum oxyhalides, the emission maximum of which is within the range from 400 to 450 nm, as the luminescent material. 6. Combination according to spoke 5 »characterized in that a phosphor of the following general formula is used Σ - Cl or Br η «0.006 - 0.0001, and wherein the halogen X is present in an amount within the stoichiometric amount and about 2.5 # thereof . 7. Combination according to claim 6, characterized in that η in the general formula means 0.002. 8. Combination according to claim #> characterized in that it contains a phosphor of the following general formula GV.7O5 509811 Pi U 7 2U1784 where mean: X chlorine or bromine, w 0.0005 to 0.006 moles of oxyhalide and y 0.00005 to 0.005 moles per mole of oxyhalide. 9. Combination according to claim 8, characterized in that that in the general formula w 0.002 mol and y 0.0005 Moles mean. 10. Combination according to at least one of claims 1 to 8, characterized in that the phosphor composition. a mixture of the lanthanum oxyhalide and a yttrium oxysulfide phosphor, activated by terbium, contains. 11.Kombination according to at least one of claims 1 to 10, characterized in that the intensifying screen in a binder dispersed fluorescent particles in an amount within the range of 85 to 95 weight - contains% and that the thickness of the fluorescent layer within the range of 60 to. 250 µm. 12. Combination according to one of the preceding claims, characterized in that the intensifying screen has fluorescent material particles with a size within of the range from about 1 to about 25 / nn. contains. 13.Kombination according to one of the preceding claimsj characterized in that the silver halide is applied to both sides of the support and a negative one Can provide a visible image, has a hiding power of about more than 50 and in ^ eder silver halide emulsion layer is present in an amount equivalent to in an amount of less than about 4 g silver per m is. · 14.Kombination according to any preceding claim, characterized marked that the silver halide with 5098 Π ft U7 one or more spectral sensitizing dyes from the class of cyanine or merocyanine dyes is sensitized. 15 combination according to one of the preceding claims, characterized in that it is a silver bromide iodide with an average grain size as the silver halide within the range of about 0.1 to about 5 µm. 16. Combination according to one of the preceding claims, characterized in that the silver halide emulsion layer (s) a color coupler contains (contain) that with an oxidized p-phenylenediamine developer substance forms a dye. 17 »Combination according to claim 16, characterized in that it contains a phenol or ύ -naphthol color coupler as a color coupler which, when the silver halide develops color with an aromatic primary amine developer, forms a quinone imine dye, which is mainly in the red area and partly in the green Area absorbed and has an absorption maximum in the spectral wavelength range from 550 to 700 nm. 18. Combination according to claim 17 »characterized in that that it contains a phenol represented by the following general formula as a color coupler wherein R- and Ep each represent a carboxylic acid acyl or sulfonic acid acyl group including the substituted groups. 19. Combination according to claim 13, characterized in that that the silver halide layers have one in common GV.705 - 34- - 509811 / 1U7 Amount of silver halide contained that is about 3 "to about 2
8 g of silver per m corresponds to »■ 20. Combination according to claim 13 or 19, characterized in that that the light-sensitive material has a silver halide emulsion layer on both sides of its support is coated and that between the silver halide emulsion layers and / or one or more filter dyes are present in these emulsion layers which are decolorized in one of the treatment baths for the silver halide light-sensitive material can. 21. Combination according to claim 20, characterized in that the pilter dye (s) has (have) a chemical structure as indicated in the description is. 22. Combination according to one of the preceding claims, characterized in that the photosensitive material has a support containing a pilter dye. 23 combination according to one of the preceding claims, characterized in that the light-sensitive material contains a filter dye or a dye mixture which absorbs in the wavelength range from 400 to 500 nm. 24. Combination according to claim 23 «characterized in that that the filter dyes are used in a hydrophilic colloid layer. 25. Combination according to one of the preceding claims, characterized in that the intensifying screen is in the form of a layer applied to a carrier or to a self-supporting layer or film. GV.705 - 35 - 50981 1 / 1U7 26. Combination according to one of the preceding claims, characterized in that the intensifying screen is separated of the light-sensitive material containing the silver halide. 27. Combination according to one of claims 1 to 251 ^ that the intensifying screen with the das Silver halide-containing light-sensitive material forms a unit. 28. Combination according to one of the preceding claims, characterized in that the x-ray fluorescence intensifier screen material one or more in the antireflection layer adjoining the phosphor layer Contains dyes and / or pigments. 29. Combination according to one of claims 1 to 28, characterized characterized in that the dye (s) and / or the figure (s) is (are) present in the layer containing the fluorescent substance (s). 30. Combination according to claim 28, characterized in that that the dye (s) and / or the pigment (s) are applied to a carrier and under the Reinforcing layer arranged anti-reflective layer are present. GV.705 - 36 - 50981 1 / 1U7