JPH07209822A - Symmetrical radiation-transmitting photograph assembly for chest examination - Google Patents

Abstract

PURPOSE: To obtain an excellent photographic sensitivity curve by specifying the sensitivity difference between at least two haloganated emulsion layers. CONSTITUTION: In a both-face radiographic component composed of a substrate and at least two haloganated emulsion layers applied both surfaces of the substrate, the haloganated emulsion layers have a sensitivity difference of at least 0.31logE and show photographic sensitivity to electromagnetic spectra in the same area and the photographic sensitivity curve of the radiographic component has a toe contrast value of >=0.45 and a mean contract value of >=1.40. It is preferable to apply a high-sensitivity emulsion to the surface of a low-sensitivity emulsion after the low-sensitivity emulsion is applied to the surface of the substrate, but the applying order of the emulsions can be changed, because the usefulness of the radiographic component is not spoiled even when the order is changed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a combination of radiation-sensitive photographic light-sensitive elements. In particular, the present invention relates to double sided coated radiographic elements for use in medical radiography, preferably chest diagnostic imaging, and their combination with a pair of fluorescent phosphor screens.

[0002]

BACKGROUND OF THE INVENTION Reducing X-ray dose to a patient using an intensifying screen is well known among medical radiographers. The intensifying screen absorbs X-rays and emits electromagnetic radiation that can be more absorbed by the silver halide emulsion layer. Another method of reducing X-ray dose to the patient is to coat both sides of the support with silver halide emulsion layers, respectively, to form a double-sided radiographic element.

Accordingly, medical radiography typically employs a radiographic assembly consisting of a double coated radiographic element sandwiched between a pair of front and back screens.

[0004]

One of the problems with medical radiography relates to the different x-ray absorption of various parts of the body. For example, in a chest radiograph, the heart region has 10 times higher absorption than the lung region. A similar effect is that the contrast medium is used to enhance the image depiction (the part of the body without the contrast medium is entirely black) and the radiograph of the stomach, and the bone is soft tissue, such as muscle and cartilage. Occurs in radiography of limbs with higher X-ray absorption.

In these cases, the radiographic component showing low contrast is required in the high X-ray absorption region, and the radiographic component showing high contrast is required in the low X-ray absorption region. The resulting film has sufficient optical density and sharpness for these different areas of the body.
Is a compromise to ensure that Chest radiographers have attempted x-ray images with visually recognizable features in both heart and lung image areas using radiographic components with increased latitude. A polydisperse silver halide emulsion is typically used for radiographic elements with increased latitude to provide lower average contrast and a wider range of exposures separating the lowest and highest density exposures. However, the extended latitude radiographic elements do not provide the desired photosensitivity curve needed to obtain visually useful image details in the heart and lung regions. The optimum sensitivity curves for obtaining good image information in both the low and high X-ray absorption regions are shown in FIG. Various methods have been proposed to solve the problem of requiring different contrast capabilities for different areas of the body. One method involves the use of double sided coated radiographic elements having different emulsion layers coated on both sides of the support. An example of this solution is disclosed in French Patent 1,103,973, in which a high contrast backside emulsion and a low contrast frontside emulsion in combination with radiographic elements coated from 1: 1 to 1.5: 1 ( Emission ratio of back screen / front screen (light emissi
The use of screens with on ratio) has been proposed. Screen with an emission ratio of 1.5: 1 or higher and similar gradation (g
A combination of radiographic elements with an emulsion layer having a radiation has also been proposed. Other patents disclose double-sided coated radiographic elements with emulsion layers having different contrasts or sensitivities. For example, German Patent 1,017,464 discloses a double-sided coated radiographic element coated with a first emulsion of high sensitivity and low contrast, and a second emulsion of low sensitivity and high contrast. No. 885,707 includes the first high-sensitivity emulsion and the second
Double coated radiographic elements coated with high contrast emulsions are disclosed. Also, French Patent No. 875,
No. 269 discloses a radiographic assembly consisting of a number of films or photographic papers, each of which can be used to obtain different and different images of the same in a single exposure. Have different sensitivities and / or contrasts to. The above-cited patents do not propose any configuration for obtaining a symmetrical double-sided coated radiographic element exhibiting the photosensitivity curve of FIG. 1 with specific features. U.S. Pat. No. 4,994,355, a method similar to that of the aforementioned French and German patent documents claims an asymmetric double-sided radiographic element having different contrast emulsion layers; asymmetric having different contrast emulsion layers. U.S. Pat. No. 4,997,750 claiming a dual side coated radiographic element; and
The back screen and emulsion layers have at least twice the photicity of the front screen and emulsion layers (photicity is the integral of the product of the screen emission and the emulsion sensitivity).
U.S. Pat. No. Claimed Asymmetric Radiographic Component Assembly (defined as rated product)
No. 5,021,327. All these proposed solutions require an asymmetric radiographic film which needs to be in a particular orientation with respect to the screen for proper use.

Further documents disclosing the situation in the field are given below. French Patent 787,017 discloses a radiographic element consisting of a silver halide emulsion layer having different color sensitivities for combination with a silver halide sensitizing radiation emitting intensifying screen. . The purpose of this patent is to obtain effective use of radiation.

EP-A-88,820 discloses a first blue-emitting phosphor layer and a second blue-emitting phosphor layer for combination with a silver halide component having spectral sensitivity in the blue-green region (the "ortho-type" component). A radiographic photographic phosphor plate comprising a green emitting phosphor layer is disclosed.

Japanese Patent No. 60-175000 discloses a combination of a double-sided coated silver halide component and a pair of screens, the fluorescent layers of the two screens having different wavelength range emission, each screen having It contains an organic dye that absorbs its emission by the opposite screen.

EP-A-350,883 provides a silver halide emulsion layer having different color sensitivities on the opposite side of a transparent support and X-ray fluorescence sensitization having emission spectra corresponding to the individual color sensitivities. Techniques for reducing crossover using a screen have been disclosed.

Research Disclosure
Disclosure) November 1973, Vol. 116, Item 11620, discloses radiographic elements showing different contrasts when observed with or without a green filter.

Finally, EP 126,644 discloses a radiation having a characteristic curve with a gamma between optical densities 0.50 and 1.50 of 2.7 to 3.3 and a gamma between optical densities 2.00 and 3.00 of 1.5 to 2.5. A radiographic material is disclosed which is a radiographic material which has a wide exposure latitude and which enables imaging with high diagnostic capabilities.

[0012]

SUMMARY OF THE INVENTION The present invention is a dual sided radiographic element comprising a support and at least two silver halide emulsion layers coated on both sides of the support, said at least two layers of halogen. Sensitization curve in which the emulsion layer shows a sensitivity difference of at least 0.3 log E, both are sensitive to the electromagnetic spectrum in the same region, and the double sided radiographic element has a toe contrast value of 0.45 or more and an average contrast of 1.40 or more For a double sided radiographic element having

In another aspect, the invention is a dual sided radiographic element comprising a support and hydrophilic colloid layers coated on both sides of the support; and an intensifying screen adjacent both sides of the radiographic element. A symmetric radiographic assembly comprising: at least two silver halide emulsion layers having a sensitivity difference of at least 0.3 log E coated on both sides of the support, each silver halide emulsion layer comprising at least two silver halide emulsion layers. Sensitive to the same region of the electromagnetic spectrum, the intensifying screen was selected to emit radiation having a maximum emission wavelength corresponding to the region of the electromagnetic spectrum in which the at least two silver halide emulsion layers are sensitive. Contains a luminescent phosphor,
And a dual-sided radiographic component having a toe contrast value of 0.45 or greater and a photosensitivity curve with an average contrast of 1.40 or greater.

In yet another embodiment, the present invention provides that (a) X-rays transmitted through an object are (i) a support and at least 0.3 log E.
A double-sided radiographic element having at least two halogenated emulsion layers coated on both sides having different sensitivity, wherein the at least two halogenated emulsion layers are each sensitive to the electromagnetic spectrum in the same region. An intensifying screen containing a radiographic element and (ii) a luminescent phosphor selected such that (ii) the at least two halogenated emulsion layers have a maximum emission wavelength corresponding to the region of the electromagnetic spectrum in which they are sensitive. Imagewise exposing a symmetric radiographic assembly comprising :; and (b) developing the exposed radiographic element, the process comprising the step of forming a radiographic image comprising:

The present invention is a dual sided radiographic element comprising a support and at least two silver halide emulsion layers coated on both sides of the support, wherein the at least two halide emulsion layers are at least 0.3. log
A double-sided radiographic image showing a difference in sensitivity of E, both of which are sensitive to an electromagnetic spectrum in the same region, and the double-sided radiographic component has a sensitivity curve having a toe contrast value of 0.45 or more and an average contrast of 1.40 or more. Regarding ingredients.

In accordance with the present invention, double sided radiographic elements are measured at a density of 1.0 above a minimum density of at least 0.3 lo.
It is composed of at least two silver halide emulsions having a difference in sensitivity of gE.

The higher sensitivity silver halide emulsion and the lower sensitivity silver halide emulsion are referred to herein as the "high speed emulsion" and the "low speed emulsion", respectively.

Where the best choice of sensitivity difference between the slow and high speed emulsions for a given application can vary widely, in most cases the first and second emulsions will range from 0.3 to 1.0 log E, optimally 0.4-0.8l
The sensitivity difference in the range of ogE is shown. In a preferred embodiment of the invention, the slow emulsion is first coated on a support, and the fast emulsion is coated on the slow emulsion, but the coating sequence does not impair the utility of the invention. It should be understood that it may be reversed by the trader. As is known to those skilled in the art, the contrast is the density difference divided by the logarithm of the difference in the exposure amount at the two density reference points of the characteristic curve, and the exposure amount is meter-candle-
Seconds. Therefore, the constant γ is expressed by the formula (I): γ = ΔD / ΔLogE
(Where ΔD is the density difference and ΔLogE is the sensitivity difference between the density reference points). The average contrast is obtained between the density reference points 0.25 and 2.00 which are equal to or higher than the minimum density. With the radiographic film of the present invention, determined using the above formula (I), 1.40 or more, preferably 1.50.
The above average contrast can be obtained.

On the contrary, the contrast value of the toe of the curve simply represents the sensitivity difference (ie ΔLogE) obtained by determining the sensitivity between 0.25 and 1.00 above the minimum density.
The radiographic film of this invention exhibits a toe contrast value of 0.45 or greater, preferably 0.55 or greater. In this case, the higher the toe contrast value (representing ΔLogE of the two density reference points), the lower the contrast obtained using the above formula (I).

In order to obtain such average contrast values and curvilinear toe contrast values, the sensitivity difference of the emulsion coated on the radiographic support is at least
0.3logE, preferably 0.3-1.0logE, optimally 0.4-0.
Should differ by 8logE. According to a preferred embodiment of the invention, the average contrast of the emulsions coated on the radiographic support should also be different from each other. The contrast of the high and low speed emulsions is at least 0.2, more preferably at least 0.3.
Should be different. According to a more preferred embodiment of the present invention,
Low sensitivity emulsion is 2.4 to 3.2, more preferably 2.6 to
The average emulsion has a mean contrast in the range of 3.0, and the fast emulsion has a mean contrast in the range of 1.8 to 2.6, more preferably 2.0 to 2.4. In general, best results are obtained when the fast and slow emulsions exhibit lower and higher contrast, respectively.

As used herein, the term "electromagnetic spectrum" refers to radiation having a wavelength of 300 to 1200 nm, ie consisting of ultraviolet radiation, visible radiation and infrared radiation.

The silver halide grains in the radiographic emulsion may have equiaxed crystal structures, such as cubic, octahedral and tetradecahedral, or spherical or disordered crystal structures, or crystal defects, such as twin planes, epitaxy. Charization (e
It may be equiaxed grains having pitaxialisation, having a tabular shape, or a combination thereof.

The term "cubic grains" according to the invention is essentially cubic grains, ie equiaxed cubic grains bound by crystal planes (100), or with rounded edges and / or tops or facets. (111), or prepared in the presence of soluble iodide or a strong ripening agent such as ammonia,
It is intended to include silver halide grains, which can be approximately spherical. The silver halide grains may also be composed of the compositions necessary to form a negative silver image, such as silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver bromochloroiodide and the like. Good. In particular, silver bromoiodide grains; preferably about 0.1-15
Silver bromoiodide grains containing mol% iodide ion, more preferably about 0.5-10 mol% iodide ion; and still preferably 0.2-3 μm, more preferably 0.4-1.5 μm.
Good results are obtained with silver bromoiodide grains having an average grain size in the m range. The preparation of silver halide emulsions having cubic silver halide grains is described, for example, in Research Disclosure 1978.
November, Volume 176, Item 17643; August 1979, Volume 184, Volume 1.
8431; and November 1989, Volume 308, Section 308119;

Other silver halide emulsions of the present invention having highly desirable imaging properties are described in US Pat. No. 4,42.
The use of one or more light sensitive tabular grain emulsions as disclosed in 5,425 and 4,425,426. The tabular silver halide grains contained in the silver halide emulsion layer of the present invention are at least 2: 1 and preferably 3: 1 to 20: 1, more preferably 3: 1 to 10: 1, and most preferably It has an average diameter: thickness ratio (often referred to by those skilled in the art as an aspect ratio) of 3: 1 to 8: 1. The tabular silver halide grains used in the present invention have an average diameter in the range of about 0.3 to about 5 μm, preferably 0.5 to 3 μm, more preferably 0.8 to 1.5 μm. Tabular silver halide grains suitable for use in this invention have a thickness of less than or equal to about 0.4 μm, preferably less than or equal to 0.3 μm, and more preferably less than or equal to 0.2 μm.

The characteristics of the tabular silver halide grains are as follows.
It can be easily confirmed by a method known to those skilled in the art. The phrase "diameter" is defined as the diameter of a circle having an area equal to the projected area of a particle. The phrase "thickne
ss) "represents the distance between the two essentially parallel major faces that make up the tabular silver halide grain. From the diameter and thickness measurements of each grain, the diameter: thickness ratio of each grain can be calculated, the diameter: thickness ratios of all tabular grains averaged, and the average diameter: thickness ratio calculated. You can ask. By this definition, the average diameter: thickness ratio is the diameter of individual tabular grains:
It is the average of the thickness ratios. In practice, it is easier to determine the average diameter and average thickness of tabular grains and to calculate the average diameter: thickness ratio as the ratio of the averages of these two. Whatever the method used, the average diameter: thickness ratios obtained do not differ significantly.

Within the silver halide emulsion layer containing tabular silver halide grains, at least 15%, preferably at least 25%, and more preferably at least 50%.
Is a tabular grain having an average diameter: thickness ratio of 3: 1 or greater. The ratio of each of the above,
"15%", "25%" and "50%" are flat plates having an average diameter: thickness ratio of at least 3: 1 to the projected area of total silver halide in the layer and a thickness of 0.4 μm or less. Represents the ratio of the total projected area of the particle.

As mentioned above, commonly used halogen compositions having silver halide grains may be used. Typical silver halides include silver chloride, silver bromide, silver chloroiodide, silver bromoiodide, silver chlorobromoiodide and the like.
However, silver bromide and silver bromoiodide are 0-10 mol%,
Preferably 0.2-5 mol%, and more preferably 0.5-
Tabular silver halide grains using silver bromoiodide containing 1.5 mol% of silver iodide are preferred. The halogen composition of the individual grains can be homogeneous or heterogeneous.

Silver halide emulsions containing tabular silver halide grains can be prepared by a variety of processes known in the art for preparing radiographic elements. The silver halide emulsions can be prepared by the acidic, neutral or ammoniacal methods, or in the presence of any other silver halide solvent. In the preparation stage, soluble silver salts and halogen salts can be mixed by the single jet method, the double jet method, and the reverse mixing.
Method, or (particle forming conditions such as pH, pAg, temperature,
The reaction can be carried out by a combined method (by adapting the shape and size of the reaction vessel and the reaction method). If desired, silver halide solvents such as ammonia, thioethers, thioureas and the like may be used to control grain size, grain shape, grain size distribution and grain growth rate.

The preparation of silver halide emulsions containing tabular silver halide grains is described, for example, by Cugnack.
nac) and Chateau (Evolution of the Morphology of Silver Bromide Crystals Dualing Physical Repening (Evolution
of the Morphology of Silver Bromide Crystals Durin
g Physical Ripening), Science and Industry Photographics (Science and Industry)
ries Photographiques), Volume 33, No. 2 (1962), 121
On page 125, Gutoff's `` Nucleation and Growth Rates Dueling the Breeditation of Silver Halide Photographic Emulsions (Nucleation and Growth Rates Du
ringthe Precipitation of Silver Halide Photographi
c Emulsions), Photographic Science and Engineering
eering) Vol. 14, No. 4 (1970), pp. 248-257, Berry, etc., "Effect of Environment on the Grouse of Silver Halide Microcrystals" (Effect of Environment on the Growth o
f Silver Halide Microcrystals ", Volume 5, No. 6 (196
1 year), pages 332-336, U.S. Pat.Nos. 4,063,951 and 4,0
67,739, 4,184,878, 4,434,226, 4,414,31
Nos. 4,386,156, 4,414,306 and European Patent Application No. 263,508.

Various hydrophilic dispersants for silver halide may be used in the preparation of the silver halide emulsions of this invention. Although other colloidal materials such as gelatin derivatives, colloidal albumin, cellulose derivatives and synthetic hydrophilic polymers may be used as known to those skilled in the art, gelatin is preferred. Other useful hydrophilic materials known to those skilled in the art are Research Disclosure (Researc
h Disclosure) Volume 308, Item 308119, Section IX. In a preferred embodiment of the invention, highly deionized gelatin is used. High deionized gelatin is characterized by high deionization with respect to commonly used photographic gelatin. Preferably, the gelatin of the present invention is almost completely deionized, which means less than 50 ppm Ca compared to commonly used photographic gelatin in which less than 5000 ppm Ca ⁺⁺ and significant amounts of other ions are present. ⁺⁺ is present and is defined as the actual absence (up to 5 ppm) of other ions such as chlorides, phosphates, sulphates and nitric acid.

Highly deionized gelatin may be used not only in the silver halide emulsion layer but also in other component layers of the radiographic element, for example in overcoat layers, interlayers and layers underlying the emulsion layer. . In the present invention, preferably at least 50% of the total hydrophilic colloid of the photographic element is used.
%, More preferably at least 70% contains high deionized gelatin. The amount of gelatin used in the light-sensitive photographic material of the present invention is such that the ratio of total silver amount / gelatin amount is 1 (expressed in g of Ag / g of gelatin) or less. In particular, the silver / gelatin ratio of the silver halide emulsion layer is in the range of 1 to 1.5.

Pre-hardening the radiographic elements of the present invention,
It can exhibit good resistance to rapid processing induced in an automatic processor without using a hardening agent in the processing liquid. Examples of gelatin hardeners include aldehyde hardeners such as formaldehyde,
Glutaraldehyde, etc .; active halogen hardeners, eg 2,
4-dichloro-6-hydroxy-1,3,5-triazine, 2-chloro
-4,6-Hydroxy-1,3,5-triazine etc .; Active vinyl hardeners such as bis-vinylsulfonyl-methane, 1,2-vinylsulfonyl-ethane, bis-vinylsulfonyl-methyl ether etc .; N- Methylol hardeners such as dimethylol urea, methylol dimethyl hydantoin, etc .; and bi
-), Tri-, or tetra-vinylsulfonyl-substituted organic hydroxy compounds such as 1.3-bis-vinylsulfonyl-2-
Propanol and the like can be mentioned. Other useful gelatin hardeners are Research Disclo
sure) Volume 308, November 1989, Item 308119, Section X.

The gelatin hardeners described above may be incorporated into the silver halide emulsion layer or the silver halide radiographic element layer having water permeability with respect to the silver halide emulsion layer. Preferably, the gelatin hardener may be incorporated in the silver halide emulsion layer.

The amount of the gelatin hardener used in the silver halide emulsion of the radiographic element of the present invention may be variously changed. Generally, the gelatin hardener is preferably in the range of 1 to 5% by weight of the hydrophilic dispersant, such as the above-mentioned highly deionized gelatin, but 0.5 to 10% by weight.
It is used in an amount in the range of.

The gelatin hardener may be added to the silver halide emulsion layer or layers of other components of the radiographic element using known techniques for preparing emulsions. For example, they may be dissolved in either water or a water-miscible solvent such as methanol, ethanol, etc.,
It may be added to the coating composition for the silver halide emulsion layer or auxiliary layer described above.

The silver halide emulsion may be chemically and optically sensitized by known methods. Spectral sensitization may be performed using various spectral sensitizing dyes known to those skilled in the art. Examples of such spectral sensitizing dyes are polymethine dyes including cyanines, complex cyanines, merocyanines, complex merocyanines, oxonol, hemioxonol, styryl, merostyryl and streptocyanines.

The intrinsic UV-blue sensitivity of silver halides is usually known, but spectral sensitizing dyes are present even when their main absorption is in the spectral region where the silver halide emulsion has its original sensitivity. By using
It can be quite useful.

Preferably, the spectral sensitizing dyes of the present invention exhibit J aggregates when absorbed on the surface of silver halide grains and have a sharp absorption band (J) with a deep chromophore shift with respect to the absorption maximum of the free dye in aqueous solution. -Indicates an absorption band. The spectral sensitizing dye that forms J aggregates is FM Hummer (H
amer) Cyanine Dyes and Related Compounds, John Wiley and Sons, 19
64, Chapter XVII and TH James The Theory of the Photographic Process
y of the Photographic Process), 4th Edition, Macmillan
(Macmillan), 1977, known to those skilled in the art as disclosed in Chapter VIII. The use of the J-absorption band, which represents a dye, reduces the known crossover problem.

Preferably, the J-absorption band representing the dye is a cyanine dye. Such dyes have two basic heterocyclic nuclei linked by a methine group. The heterocyclic nucleus preferably contains fused benzene rings that promote J aggregation.

The heterocyclic nucleus is preferably quinolinium, benzoxazolium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium and naphthoselenazolium quaternary. There is grade salt.

Preferably, the J-absorption type dye used in the present invention has a structure represented by the following general formula (I).

[Chemical 1] In the formula, Z ₁ and Z ₂ may be the same or different,
Respective basic heterocyclic nitrogen compounds such as oxazoline, oxazole, benzoxazole, naphthoxazoles (eg, naphtho {2,1-d} oxazole, naphtho {2,3-d} oxazole and naphtho {1,2-d } Oxazole), thiazoline, thiazole, benzothiazole, naphthothiazoles (for example, naphtho {2,1-d} thiazole), thiazoloquinolines (for example, thiazolo {4,5-b} quinoline), selenazoline, selenazole,
Benzoselenazole, naphthoselenazoles (for example,
Naphtho {1,2-d} selenazole), 3H-indole (eg, 3,3-dimethyl3H-indole), benzindoles (eg, 1,1-dimethylbenzindole), imidazoline, imidazole, benzimidazole, naphtho Represents the components necessary to complete a cyclic nucleus derived from imidazoles (eg, naphtho {2,3-d} imidazole), pyridine and quinoline; the nucleus being one or more different substituents within the ring, For example, hydroxy, halogens (for example,
Fluorine, bromine, chlorine and iodine), an alkyl group or a substituted alkyl group (for example, methyl, ethyl, propyl,
Isopropyl, butyl, octyl, dodecyl, 2-hydroxyethyl, 3-sulfopropyl, carboxymethyl, 2-
Cyanoethyl and trifluoromethyl), aryl or substituted aryl groups (eg phenyl, 1-naphthyl, 2-naphthyl, 4-sulfophenyl, 3-carboxyphenyl and 4-biphenyl), aralkyl groups (eg benzyl and phenethyl ( Phenethyl)), alkoxy groups (eg methoxy, ethoxy and isopropoxy), aryloxy groups (eg phenoxy and 1-
Naphthoxy), alkylthio groups (eg ethylthio and methylthio), arylthio groups (eg phenylthio, p-tolylthio and naphthylthio), methylenedioxy, cyano, 2-thienyl, styryl, amino or substituted amino groups (eg anilino, dimethyl). Anilino,
Diethylanilino and morpholino), acyl groups (eg acetyl and benzoyl) and sulfo groups, R ₁ and R ₂ may be the same or different and may or may not have substituents. Not alkyl, aryl or aralkyl groups (eg carboxymethyl, 2-hydroxyethyl, 3-sulfopropyl, 3-
Sulfobutyl, 4-sulfobutyl, 2-methoxyethyl, 2-
(Sulfate ethyl, 3-thiosulfate ethyl, 2-phosphonoethyl, chlorophenyl and bromophenyl)
R ₃ represents a hydrogen atom, R ₄ and R ₅ may be the same or different and represent a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and p and q are
is 0 or 1 except that both p and q are not 1, and m is m is 1 when both p and q are 0 and at least one of Z ₁ and Z ₂ is imidazoline, oxazoline, 0 or 1 except for thiazoline or selenazoline, A is an anionic group, B is a cationic group, and k and l are 0 or 1 depending on whether an ionic substituent is present. May be.

Of course, R ₁ and R ₃ , R ₂ and R ₅ ,
Alternatively, variations are possible in which R ₁ and R ₂ together represent the atoms necessary to complete an alkylene bridge.

Other publications on known spectral sensitizers include Research Disclosure 1989.
Vol. 308, Item 308119, Section IV, November, 2013. Research Disclosu
re) is a PO10 7DD in Emsworth, Hampshire.
worth) Kennis Mason Publications (KennethMa
son Publication) is a publication of the company.

In the most preferred configuration of the present invention, the silver halide emulsion is absorbed on silver halide grains,
Spectral sensitization is performed using a spectral sensitizing dye represented by the following general formula (II).

[Chemical 2] In the formula, R ₁₀ represents a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms (eg, methyl and ethyl), and R ₆ , R ₇ , R ₈ and R ₉ represent a hydrogen atom and a halogen atom, respectively. (Eg chlorine, bromine, iodine and fluorine), hydroxy groups, alkoxy groups (eg methoxy and ethoxy), amino groups (eg amino, methylamino and dimethylamino), acylamino groups (eg acetamide and propionamide), Acyloxy group (eg acetoxy group), alkoxycarbonyl group (eg methoxycarbonyl, ethoxycarbonyl and butoxycarbonyl), alkyl group (eg methyl, ethyl and isopropyl), alkoxycarbonylamino group (eg ethoxycarbonylamino) or aryl Represents a group (eg, phenyl and tolyl), both of which are R ₆ and R ₇ , and R _{8 respectively.}
And R ₉ may be the atoms necessary to complete the benzene ring (so that the heterocyclic nucleus is, for example, an a-naphthoxoxazole nucleus, b-naphthoxazole or b, b′-naphthoxazole). , R ₁₁ and R ₁₂ are each an alkyl group (eg, methyl, propyl and butyl), a hydroxyalkyl group (2-hydroxyethyl, 3-hydroxypropyl and 4-hydroxybutyl), an acetoxyalkyl group (eg, 2-acetoyl). Oxyethyl and 4-acetooxybutyl), alkoxyalkyl groups (eg,
2-methoxyethyl and 3-methoxypropyl), carboxyl groups having alkyl groups (eg carboxymethyl, 2-carboxyethyl, 4-carboxybutyl and 2-
(2-carboxyethoxy) ethyl), a sulfo group having an alkyl group (for example, 2-sulfoethyl, 3-sulfopropyl, 4-sulfobutyl, 2-hydroxy-3-sulfopropyl, 2- (3-sulfopropoxy) propyl, p-sulfobenzyl and p-sulfophenethyl), a benzyl group, a phenethyl group, a vinylmethyl group and the like, and X ⁻ represents an acid anion (eg, chloride, bromide, iodide, thiocyanate, methyl sulfate, ethyl sulfate, Perchloric acid, and p-toluenesulfonate ion), and n is 1 or 2
Represents

The alkyl group has the substituents R ₆ , R ₇ , R ₈ and
R <_9> , R < ₁₀ > and R < ₁₁ >, especially having an alkyl part of said alkoxy, alkoxycarbonyl, alkoxycarbonylamino, hydroxyalkyl, acetoxyalkyl group and 1-12, more preferably 1-4 carbon atoms. Including the alkyl part of the alkyl group bonded to a carboxy or sulfo group, the total number of carbon atoms in the group is
20 or less.

The aryl group containing the substituents R ₆ , R ₇ , R ₈ and R ₉ each preferably has 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms, and the total amount of the group. It has no more than 20 carbon atoms.

Specific examples of J-absorption zone sensitizing dyes belonging to those represented by the general formula (II) are shown below.

[Table 1]

The silver halide emulsion layer contains other components generally used in photographic products such as binders, hardeners, surfactants, sensitizers, stabilizers, plasticizers, gelatin extenders, optical sensitizers, Dyes, UV absorbers, etc. may be included, and such components are described, for example, in Research Disclosure, November 1978, No. 176.
Vol. 17643; August 1979, Vol. 184, Para. 18431; and Nov. 1989, Vol. 308, Para. 308119;

The radiographic elements of this invention may be prepared by coating a light sensitive silver halide emulsion layer and other auxiliary layers on a support. Examples of suitable materials for making the support are glass, paper, polyethylene coated paper, metal, polymer films such as cellulose nitrate,
Examples include cellulose acetate, polystyrene, polyethylene terephthalate, polyethylene, polypropylene, and other known supports. Preferably, the silver halide emulsion layer on a support, at least 1 g / m ^2, preferably coated at a total silver coverage comprised in the range of 2-5 g / m ^2.

The auxiliary layer is a top coat layer, an antistatic layer,
You may express as a halo prevention layer, a protective layer, a dye lower layer, etc. Dye sublayers are particularly useful in reducing crossover in the double-sided coated silver halide radiographic materials of this invention. Known dye underlayer, U.S. Pat.No. 4,900,652,
No. 4,855,221, No. 4,857,446, and No. 4,803,150. According to a preferred embodiment of the invention, the dye underlayer is coated on at least one side of the support, more preferably both sides of the support, and at least two silver halide emulsions thereof.

In another embodiment, the invention comprises a double sided radiographic element comprising a support and hydrophilic colloid layers coated on both sides of the support; and an intensifying screen adjacent to both sides of the radiographic element. A symmetrical radiographic assembly, wherein at least two silver halide emulsion layers having a sensitivity difference of at least 0.3 log E are coated on both sides of said support, said at least two silver halide emulsion layers each being in the same area. Phosphorescent material which is sensitive to the electromagnetic spectrum of and the intensifying screen is selected to emit radiation having a maximum emission wavelength corresponding to the electromagnetic spectrum region in which the at least two silver halide emulsion layers are sensitive. Substance, and the double-sided radiation transmitting component has a toe contrast value of 0.45 or more and 1.4. A symmetrical radiographic assembly having a photosensitivity curve with an average contrast of 0 or greater.

As used herein, the term "symmetric radiographic assembly" comprises a silver halide double-sided coated radiographic element consisting of substantially identical silver halide emulsion layers coated on both sides of a support. 2 represents a radiographic assembly, the radiographic element being between a pair of intensifying screens.

The radiographic elements of this invention are exposed with an intensifying screen to the radiation emitted by that screen. The pair of screens used in combination with the radiographic elements of this invention are symmetrical. The screen is
It consists of a relatively thick phosphor layer that converts X-rays into radiation (eg, visible light). The screen is part of X
It absorbs much more radiation than radiographic elements and is used to reduce the radiation dose required to obtain a useful image.

The phosphors used in the intensifying screens used in the present invention include ultraviolet, blue, green, red or infrared regions of the electromagnetic spectrum which correspond to the electromagnetic spectrum region in which at least two silver halide emulsion layers are sensitive. Has the maximum wavelength of light emission. More preferably, the phosphor emits radiation in the ultraviolet, blue and green regions of its electromagnetic spectrum.

Green emitting phosphors are about 80% or more at 480 nm.
Emit radiation with the above spectral emission and emission maxima in the wavelength range of 530-570 nm. Green emitting phosphors that can be used in the intensifying screen of the present invention include yttrium,
Rare earth active rare earth oxysulfide phosphors having at least one rare earth element selected from lanthanum, gadolinium and lutetium; rare earth active rare earth oxyhalide phosphors having similar rare earth elements; said rare earth elements And a phosphorescent substance composed of the rare earth element phosphate, and a phosphorescent substance composed of the rare earth element tantalate. These rare earth green light-emitting phosphors are widely used in patent documents, for example, U.S. Patent Nos. 4,225,653, 3,418,246, and 3,418,
No. 247, No. 3,725,704, No. 3,617,743, No. 3,974,389
No., No. 3,591,516, No. 3,607,770, No. 3,666,676,
No. 3,795,814, No. 4,405,691, No. 4,311,487 and No. 4,387,141. These rare earth phosphors have high X-ray absorptivity and high emission efficiency upon excitation with X-rays, and can be used by radiologists at substantially lower doses of X-rays.
It is possible to use lines. Particularly suitable phosphors for use in intensifying screens of the present invention have the following general formula: selected _{(Ln 1-ab, Tb a} , Tm b) in ₂ O ₂ S (wherein, Ln is lanthanum, gadolinium and lutetium At least one rare earth element,
And a and b are numbers such that 0.0005 ≦ a ≦ 0.09 and 0 ≦ b ≦ 0.01 respectively) and terbium or terbium-thulium active rare earth oxysulfide phosphors, and the following general formula: _{(Y 1-ca, Ln c} , Tb a, Tm b) in ₂ O ₂ S (wherein, Ln is at least one rare earth element selected from lanthanum, gadolinium and lutetium,
And a and b are 0.0005 ≦ a ≦ 0.09 and 0 ≦, respectively.
terbium or terbium-thulium-activated rare earth oxysulfide phosphors represented by the formulas b ≦ 0.01 and 0.65 ≦ c ≦ 0.95).

UV-blue emitting phosphors contain about 80% or more of 450
Emit radiation with sub-nm spectral emission and emission maxima in the 300-400 nm wavelength range. UV-blue emitting phosphors that can be used in the intensifying screen of the present invention include UV-blue emitting phosphors known to those skilled in the art, such as lead or lanthanum activated barium sulfate phosphors; fluorohalogenated barium phosphors; lead activated. Barium silicate phosphors; gadolinium active yttrium oxide phosphors; barium fluoride phosphors; alkali metal active rare earth niobate or tantalate phosphors and the like. UV-blue emitting phosphors are, for example, Belgian patents 703,998 and 757,8.
No. 15, European Patent No. 202,875, and View Canan (Bu
chanan) and other journals of applied physics
(J. Applied Physics), Volume 9, 4342-4347, 1968.
Year, and Clapp and Ginther Journal of the Optical Society of America, 37th
Vol. 355-362, 1947. Particularly suitable UV-blue emitting phosphors for use in the intensifying screen of the present invention are of the general formula: (Y _{1-2 / 3x-1 / 3y} , Sr _x , Li _y ) TaO _{4 where} x And y are numbers such that 10 ⁻⁵ ≦ x ≦ 1 and 10 ⁻⁴ ≦ y ≦ 0.1, as disclosed in EP 202,875).

Other known types of luminescent phosphors are disclosed in Research Disclosure, August 1979, Volume 184, Item 18431, Section IX.

The intensifying screen of the present invention has a fluorescent layer comprising a binder and at least one phosphor dispersed therein. Dispersing the phosphor layer in a binder to prepare a coating dispersion having the desired phosphor weight ratio; then coating the coating dispersion by conventional coating methods to form a uniform layer; Formed by. While the fluorescent layer may be the intensifying screen itself when the fluorescent layer is self-supporting, the fluorescent layer generally provides a support to form the intensifying screen. Further, a protective layer that physically and chemically protects the fluorescent layer is usually formed on the surface of the fluorescent layer. Further, sometimes a primer layer is formed between the fluorescent layer and the support, the fluorescent layer is intimately adhered to the support, and a reflective layer is sometimes formed between the support (or primer) and the fluorescent layer.

The binder used in the fluorescent layer of the intensifying screen of the present invention is, for example, one kind of binder usually used for layer formation: gum arabic, proteins such as gelatin, polysaccharides such as dextran, organic polymer binders, for example. It may be polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride-vinyl chloride copolymer, polymethyl methacrylate, polybutyl methacrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, etc. .

Generally, the binder is used in an amount ranging from 0.01 to 1 part by weight per part by weight of phosphor. However, from the viewpoint of sensitivity and sharpness of the obtained screen, the amount of the binder should preferably be small. Thus, taking into account both the sensitivity and sharpness of the screen and the ease of application of the coating dispersion, the binder is preferably 0.03-0.
Used in an amount in the range of 2 parts by weight. The thickness of the fluorescent layer is generally 1
It is in the range of 0 μm to 1 mm.

In the intensifying screen of the present invention, a fluorescent layer is generally coated on a support. Various materials may be used as the support, for example polymeric materials, glass, wood, cotton, paper, metal and the like. From a screen handling standpoint, the support should preferably be processed into a flexible sheet or roll. In this regard, the support is preferably a plastic film (for example, cellulose triacetate film, polyester film, polyethylene terephthalate film, polyamide film, polycarbonate film, etc.), or plain paper or treated paper (for example, photographic paper, baryta paper, Resin-coated paper, pigment-containing paper containing pigments such as titanium dioxide, etc.). The support may have a primer layer on one surface (the surface providing the fluorescent layer) to firmly immobilize the fluorescent layer. A normal adhesive may be used as the material for the primer layer. When the fluorescent layer is provided on the support (or the primer layer or the reflective layer), the coating dispersion containing the phosphor dispersed in the binder is provided on the support (or the primer layer or the reflective layer). ) Directly.

Further, in the intensifying screen of the present invention, a protective layer for physically or chemically protecting the fluorescent layer is generally provided on the surface of the fluorescent layer to be exposed (opposite to the support). The protective layer may be provided directly on the fluorescent layer by directly applying the coating dispersion to form the protective layer,
It may be provided by adhering a preformed protective layer. As the material for the protective layer, conventional materials for the protective layer, such as nitrocellulose, ethyl cellulose, cellulose acetate, polyester, polyethylene terephthalate, etc. may be used.

The intensifying screen of the present invention may be colored with a dye. Further, the fluorescent layer may have dispersed white powder. The use of dyes or white powders can result in intensifying screens that provide high sharpness images.

In a further aspect, the invention provides: (a) X-rays transmitted through an object, particularly an animal or human body for medical radiographic imaging, (i) a support and at least 0.3. A dual-sided radiographic element having at least two halogenated emulsion layers coated on both sides having a difference in log E, wherein the at least two halogenated emulsion layers are each sensitive to the electromagnetic spectrum in the same region. Double sided radiographic component, and (i
i) A symmetric radiographic image consisting of an intensifying screen containing a luminescent phosphor selected such that said at least two halogenated emulsion layers emit a radiation having a maximum emission wavelength corresponding to a region of the electromagnetic spectrum of light sensitivity. Imagewise exposing the assembly; and (b)
Developing the exposed radiographic element; and forming a radiographic image.

In addition to the features specifically mentioned above, the radiographic elements of this invention have been incorporated into Research Disclosure (Research Disclosure) layers in silver halide emulsion layers or in other layers.
Disclosure) Nov 1978, Volume 176, Item 17643;
August 184, Vol. 18431; and November 1989, Vol.
308, 308119; further addenda having conventional properties, such as stabilizers, antifoggants, brighteners, absorbers, hardeners, coating aids, plasticizers. Agents, lubricants, matting agents, anti-kinking agents, antistatic agents and the like may be included.

Regarding the processing for preparing silver halide emulsions and the use of specific components for the emulsions and photosensitive components, Research Disclosure (Resear
chDisclosure) Paragraph 18431, disclosed in August 1979, covers the following chapters in more detail; IA. Preparation of silver halide emulsions, purification and concentration methods IB. Emulsion type IC. Crystal chemistry enhancement Feeling and doping II. Stabilizers, antifoggants and antifolds
Ingredients IIA. Stabilizers and / or antifoggants IIB. Stabilization of emulsions chemically sensitized with gold compounds IIC. Stabilization of emulsions containing polyalkylene oxides or plasticizers IID. Fogging caused by foreign metal IIE. Stabilization of materials containing agents that increase coating ability IIF. Antifoggants for dichroic fog IIG. Antifoggants for developers containing hardeners and hardeners IIH. Desensitization by bending ( Defoaming additive III. Antifoggant for emulsion coated on polyester support IIJ. Stabilization method for emulsion with safe light IIK. Stabilization method for high temperature use X-ray material, roller processor transfer treatment Rapid access III. Compounds and antistatic layers IV. Protective layers V. Direct positive materials VI. Materials for processing in room light VII. X-ray color materials VIII. Phosphors and reinforcing papers IX. Spectral sensitization X. UV exposure Fee XII. Support

[0067]

The present invention is illustrated by the following examples, but the invention is not limited thereto.

84.4 mol% bromine, 14.4 mol% chlorine and 1.
An octahedral silver chlorobromide iodide emulsion (Em.A) containing 2 mol% iodine was chemically and sulfur sensitized with gold thiocyanate complex, sodium p-toluenesulfonate and benzothiazole iodoethylate. , Green sensitization fee,
Spectral sensitized with anhydrous 5,5-dichloro-9-ethyl-3,3'-bis- (3-sulfopropyl) oxacarbocyanine hydroxide-triethylamine salt and added resorcyl aldehyde and dimethylol urea hardener . The silver halide grains are
It had an average crystal diameter of 0.7 μm. Emulsion A exhibited an average contrast of about 2.8 when coated on both sides of the polyester support. 99.4 mol% bromine and 0.6 mol%
Tabular silver bromoiodide emulsion containing iodine (Em.B)
Was chemically and spectrally sensitized as Emulsion A above. The tabular silver halide grains have an average diameter of 0.35 μm,
The average thickness was 0.25 μm and the aspect ratio was 5.4. When coating both sides of the polyester support, use emulsion B
Showed an average contrast of about 2.3. Emulsions A and B showed a sensitivity difference of about 0.5 log E.

(Radiographic Photographic Film 1 (Invention)) Emulsion A was used as the first emulsion layer on both sides of a 0.18 mm-thick blue polyester film, and both sides were coated with silver.
Coated with 1.3 g / m ² . An emulsion mixture was prepared by mixing equal parts (based on silver content) of emulsions A and B. This emulsion mixture
The film was coated on both sides of the first emulsion layer with a silver coating weight of 1.0 g / m ² . 0.9 μm for both emulsion layers
A gelatin topcoat was applied at a gelatin thickness of.

(Radiographic Film 1 (Invention)) Emulsion A was used as the first emulsion layer on both sides of a 0.18 mm thick blue polyester film, and both sides were coated with silver.
Coated with 1.5 g / m ² . Emulsion B was coated on the first emulsion layer on both sides of the film with a silver coating weight of 1.0 g / m ² . A gelatin topcoat was applied to both emulsion layers with a gelatin thickness of 0.9 μm. Both films 1 and 2 were provided with two 3M Trimax ^™ T8 screens and also with 3M Trimax ^™ T6 and
Exposed using a combination of T16 screens. Trimax ^TM T6 screen has a phosphor coating area of 500 g / m
² and coated with a hydrophobic polymer binder on a polyester support with a coating thickness of 139 μm, average particle size 3.5 μm
Is a 3M medium resolution screen consisting of the terbium activated gadolinium oxysulfate phosphor of. The Trimax ^TM T8 screen is a phosphor coated area
Average particle size coated with a hydrophobic polymer binder on a polyester support at 420 g / m ² and a coating thickness of 105 μm.
3M medium resolution screen consisting of 8.2 μm green emitting terbium activated gadolinium oxysulfate phosphor. Trimax (Trimax ^TM) T8 screen, phosphor coverage of 1050 g / m ² and was coated with a hydrophobic polymer binder on a polyester support in coating thickness 250 [mu] m, terbium active oxysulfate gadolinium phosphor having an average particle diameter of 5.5μm Is a high-sensitivity screen manufactured by 3M. 3M XLA ^™ Radiographic Film
(Radiographic Film) and Kodak Insight ^™ Chest Film were also used as controls. 3M XLA ^™ Radiographic Film is a conventional radiographic film with wide latitude, Kodak Insight
Chest film (Kodak Insight ^TM Chest Film)
An asymmetric radiographic film having a high contrast and low sensitivity emulsion on one side and a low contrast and high speed emulsion on the other side.

The exposed film was treated with 3M Trima (Trima).
A tic ^™ XP515 automatic processor was used with a developer and fixer having the following compositions with a total processing time of 90 seconds. Developer KOH (35 wt% solution) 105 g Acetic acid 7.6 g Glutaraldehyde (50 wt% solution) 7.2 g Sodium metabisulfate 45.0 g Ethylene glycol 10.0 g Diethylene glycol 4.9 g Morpholinomethane diphosphonic acid (40 wt% solution) 7.2 g 5- Methylbenzotriazole 80.0 mg 5-Nitroindazole 107.0 mg 1-phenyl-1-H-tetrazole-5-thiol 7.0 mg Boric acid 1.7 g Potassium carbonate 13.25 g Ethylenediaminotetraacetic acid .4 Na.2H ₂ O 1.5 g 1-phenyl- 3-Pyrazolidone 1.45 g Hydroquinone 20.0 g NaBr 5.0 g Preparation water 1 pH 10.35 Fixing agent Ammonium thiosulfate 145.2 g Sodium sulfite 8.12 g Boric acid 7.0 g Acetic acid 7.52 g Ammonium acetate 19.24 g Ammonium sulfate 7.74 g Sulfuric acid 3.58 g 2-Phenoxyethanol 0.12 g Preparation water 1 pH 4.30

The photosensitivity measurement results are shown in Tables 1 and 2 below. Table 1 T8 + T8 screen 75kV X-ray irradiation film Sensitivity Average contrast Foot contrast value Dmax Film 1 2.43 1.60 0.62 3.43 Film 2 2.33 1.55 0.69 3.47 3M XLA ^TM 2.54 2.15 0.41 3.50 Kodak Insight 2.56 2.15 0.43 4.25 (Kodak Insight ^TM ) Table 2 T6 + T16 screen 75kV X-ray irradiation film Sensitivity Average contrast Foot contrast value Dmax Film 1 2.49 1.65 0.61 3.43 Film 2 2.39 1.58 0.68 3.44 3M XLA ^TM 2.58 2.15 0.41 3.50 Kodak Insight 2.56 1.92 0.51 4.20 (Kodak Insight ^TM ).

The data in Tables 1 and 2 clearly show that the toe contrast values and the average contrast of the curves of the inventive films 1 and 2 are improved, which is very close to the ideal curve of FIG. Similar sensitivity curves can be provided.

Kodak Insights Film
have a ight ^TM Film) is asymmetric structure is that worthless as disclosed in U.S. Patent No. 4,994,355 described above, thus requiring a specific direction in order to work well. Furthermore, Tables 1 and 2 clearly show that Kodak Insight ^™ Film also provides different results with respect to average contrast and toe contrast values using different screens. On the contrary, both film 1 and film 2 retained similar photosensitivity characteristics, even when the screen combination was changed or reversed. The radiographic film of this invention does not require any special attention by the operator regarding the orientation and / or type of intensifying screen and is therefore easier to handle than conventional chest radiographic films.

[Brief description of drawings]

FIG. 1 shows that in both the low and high X-ray absorption regions, especially in the chest, compared to the standard photosensitivity curve,
This is a photosensitivity curve that is optimum for obtaining good image formation information.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03C 5/29 G21K 4/00 A (72) Inventor Ena Marinelli Italy 17016 Ferrania (Savona) (Street address) Not displayed) 3M Italia A Richerche Societa Pell Achioni

Claims (19)

[Claims] 1. A double sided radiographic element comprising a support and at least two silver halide emulsion layers coated on both sides of said support, said at least two halide emulsion layers having at least 0.3 log E. A dual-sided radiographic element exhibiting a difference in sensitivity, both of which are sensitive to the same region of the electromagnetic spectrum, and wherein said double-sided radiographic element has a photosensitivity curve having a toe contrast value of 0.45 or greater and an average contrast of 1.40 or greater. 2. The radiographic element according to claim 1, wherein the difference in sensitivity is in the range of 0.3 to 1.0 log E. 3. A radiographic element according to claim 1 wherein said at least two silver halide emulsion layers exhibit an average contrast difference of at least 0.2. 4. The average contrast of the silver halide emulsion layer having the lowest sensitivity is in the range of 2.4 to 3.2,
A radiographic element according to claim 1, wherein the average contrast of the silver halide emulsion layer having the highest sensitivity is in the range of 1.8 to 2.6. 5. The radiographic element according to claim 1, wherein the toe contrast value of the curve is 0.55 or more. 6. At least one of said two silver halide emulsion layers has an average grain thickness of 0.3 μm or less and a grain size of less than 0.3 μm.
A radiographic element according to claim 1 which comprises a tabular grain emulsion having an average grain diameter of 5 µm or greater. 7. A radiographic element according to claim 6 wherein said tabular grain emulsion comprises tabular grains having an average aspect ratio of 2: 1 or greater. 8. The tabular grain emulsion comprises 5: 1 to 1
A radiographic element according to claim 6 having tabular grains having an average aspect ratio in the range of 0: 1. 9. A radiographic element according to claim 1 wherein the first coated silver halide emulsion layer exhibits less sensitivity than the second coated silver halide emulsion layer. 10. A radiographic element according to claim 1, wherein the first coated silver halide emulsion layer exhibits higher sensitivity than the second coated silver halide emulsion layer. 11. A radiographic element according to claim 1, wherein a dye sublayer is coated on at least one side of the support. 12. A double-sided radiographic element comprising a support and a hydrophilic colloid layer coated on both sides of the support;
And a intensifying screen adjacent to both sides of the radiographic element; at least two silver halide emulsion layers having a sensitivity difference of at least 0.3 log E on both sides of the support. The at least two silver halide emulsion layers are each sensitive to the same region of the electromagnetic spectrum and the intensifying screen is sensitive to the electromagnetic spectrum region of the at least two silver halide emulsion layers. Containing a luminescent phosphor selected to emit radiation having an emission maximum wavelength corresponding to, and said double-sided radiation transmissive component has a photosensitivity curve having a Toe contrast value of 0.45 or greater and an average contrast of 1.40 or greater, Symmetric radiographic assembly. 13. The radiographic assembly according to claim 12, wherein the sensitivity difference is within the range of 0.3 to 1.0 log E. 14. A radiographic assembly according to claim 12, wherein said first and second silver halide emulsions exhibit a sensitivity difference of at least 0.2. 15. The emulsion layer having the lowest sensitivity has an average contrast in the range of 2.4 to 3.2, and the emulsion layer having the highest sensitivity has an average contrast of 1.
13. A radiographic assembly according to claim 12, in the range of 8 to 2.6. 16. A radiographic assembly according to claim 12, wherein at least one of said two emulsion layers comprises a tabular grain emulsion having an average grain thickness of 0.3 μm or less and an average grain diameter of 0.5 μm or more. . 17. A radiographic assembly according to claim 16 wherein said tabular grain emulsion comprises tabular grains having an average aspect ratio of 3: 1 or greater. 18. The tabular grain emulsion comprises 5: 1 to
A radiographic assembly according to claim 16 having tabular grains having an average aspect ratio in the range of 10: 1. 19. A dual sided radiographic element having (a) X-rays transmitted through an object, (i) a support and at least two halogenated emulsion layers coated on both sides having a sensitivity difference of at least 0.3 log E. A double-sided radiographic element in which the at least two halogenated emulsion layers are each sensitive to the electromagnetic spectrum in the same region, and (ii) the electromagnetic spectrum in which the at least two halogenated emulsion layers are photosensitive. Imagewise exposing a symmetrical radiographic photographic assembly comprising an intensifying screen containing a luminescent phosphor selected to emit radiation having an emission maximum wavelength corresponding to a region; and (b) said exposing radiation transmission. Developing a photographic element; the process of forming a radiographic image comprising: