JPH0328842A - Radiographic element with selected contrast relation - Google Patents

Abstract

PURPOSE: To increase the information content of an image of an object to be photographed which differ in a wide range in X-ray absorption density by specifying the contrast of a 1st and a 2nd silver halide emulsion layer unit. CONSTITUTION: The 1st silver halide emulsion layer unit 115 shows the average contrast of <2.0, and on the other hand, the 2nd silver halide emulsion layer unit 117 shows the average contrast of 2.5. And the contrast and other sensitometric characteristics of the 1st silver halide emulsion layer unit 115 are fixed by replacing the 2nd silver halide emulsion layer unit 117 by the 1st silver halide emulsion layer unit 114, so that the 1st silver halide emulsion layer unit 115 exists on both sides of a transparent supporting body. The contrast and other sensitometic characteristics of the 2nd silver halide emulsion layer unit 117 are fixed by replacing the 1st silver halide emulsion layer unit 115 by the silver halide emulsion layer unit 117, so that the 2nd silver halide emulsion layer unit 117 exists on both sides of the transparent supporting body. As a result, the contrast is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to radiographic elements, and more particularly to double-coated silver halide radiation of the type used in conjunction with an intensifying screen. Concerning photographic elements.

[Conventional technology]

In medical radiography, images of a patient's tissues and bone structures are obtained by exposing the patient to X-ray radiation and at least one radiation-sensitive silver halide film coated on a transparent (generally bluish) film support. It is created by recording a pattern of transmitted X-ray radiation using a Radiographic element that includes an emulsion layer. XLA radiation can be recorded directly by the emulsion layer when only limited area exposure is required, such as in dental imaging and body limb imaging. However, a more effective approach to greatly reducing X-ray radiation exposure is to use intensifying screens in combination with radiographic elements. Intensifying screens absorb X-ray radiation and emit longer wavelength electromagnetic radiation, which silver halide emulsions absorb more easily. Another method to reduce patient exposure is to coat two silver halide emulsion layers on opposite sides of the film support, creating a "double coat" radiographic element.

Diagnostic needs are met by the lowest patient x-ray radiation exposure levels through the use of a double coated radiographic element in combination with a pair of intensifying screens. The silver halide emulsion layer units on each side of the support directly absorb about 1-2% of the incident X-ray radiation. front intensifying screen
The backscreen, i.e., the intensifying screen closest to the XI radiation source, absorbs a higher percentage of X-ray radiation, but still exposes the backscreen, i.e., the intensifying screen furthest from the X-ray radiation source. Transmits enough X-ray radiation to In the vast majority of applications, the front and rear intensifying screens are balanced so that each absorbs approximately the same proportion of the total x-ray radiation. However, slight deformations have been reported from time to time. A particular example of balancing front and rear intensifying screens to maximize image sharpness is disclosed in U.S. Pat. No. 4.71 to Luckey et at.
No. 0,637. Lyonset
U.S. Pat. No. 4,707.435 to al.
0, Trimax 2TM used as a front intensifying screen and Trimax 12FT1'' used as a post intensifying screen.
A combination of two proprietary intensifying screens is disclosed. K. Rossmaa and G. Sanderson
is “Validity of the Modula”
tionTransfer Function of
Radiographic Screen-FilmS
systems Measured by the Sl
Phys.Med.Biol
．． , 1968, Volume 13, No. 2, 259-268
The page describes an asymmetric intensifying screen-film assembly in which the two screens have measurably different optical properties or the two emulsions have measurably different optical properties. reported using.

Imagewise exposed double coated radiographic elements contain latent images in each of two silver halide emulsion layer units on opposite sides of the film support.

The development process converts the latent image into a silver image and also fixes any undeveloped silver halide, making the film invisible to light. This film is placed in the inspection box (view box).
x), the two overlapping silver images on opposite sides of the support appear to be a single image against a white illuminated background.

It has been a continuing objective of medical radiography to maximize the information content of diagnostic images while minimizing patient exposure to xl radiation. In 1918, Easts+an
The Kodak Company introduces the first dual-coated medical radiography product, the Petterson Sc
The reenCompany introduced matched intensifying screen pairs for its products that same year.

A technique that has been found to be difficult with the use of double-coated radiographic elements in combination with intensifying screens as described above is that some light emitted by each intensifying screen is directed to the opposite side of the support. passing through a transparent film support to expose the silver halide emulsion layer unit to light.

Light emitted by the intensifying screen, which exposes the emulsion layer unit on the opposite side of the support, reduces image sharpness. This effect is due to the cross-over effect in the technology.
over).

The most successful approaches to crossover reduction have still been realized with techniques consistent with the idea of viewing superimposed silver images through a transparent film support without manual registration of the images.
U.S. Pat. No. 4,425,42 to Abbott et al.
No. 5 and No. 4,425,426, respectively, using double coated radiographic elements comprising spectrally sensitized high aspect ratio tabular grain emulsions or thin medium aspect ratio tabular grain emulsions. It was to do.

^As opposed to prior to Abbott et al., where radiographic elements typically exhibited crossover levels of at least 25%, Abbott et al.
Examples of crossover reductions in the range of ~22% are shown.

More recently, U.S. Pat. No. 4,803,150 to Diekerson et al.
It has been shown that "zero" crossover levels can be achieved by combining the teachings of al. with a processing solution decolorizable microcrystalline dye disposed between at least one of the emulsion layer units and a transparent film support. .

The method used to determine crossover is a single intensifying screen exposure of a double-coated radiographic element, in which the emulsion layer on the side of the support remote from the intensifying screen caused by the crossover Because it is not possible to distinguish between exposure caused by direct absorption of X-ray radiation and exposure caused by direct absorption of X-ray radiation, a "zero" crossover radiographic element actually has a measured Includes radiographic elements with crossovers. The particular selection of dye-containing layers to create a "zero" crossover radiographic element with a hydrophilic colloid coating in the emulsion
Conventional rapid access processing in less than 90 seconds with decolorized cross-over reduced microcrystalline dyes.
Dry until contact from ss processor).

Although great improvements in radiographic elements have been made over the years, certain limitations have heretofore been accepted as an inherent result of the complexity of medical diagnostic imaging. Medical diagnostic images place extreme and varied demands on radiographic elements. One of the most difficult requirements can be exemplified by a chest X-ray, in which in a typical chest X-ray the X-ray radiation absorption in the heart region is greater than the Ladle too! Although times greater, radiologists are faced with the challenge of visually detecting both lung and cardiac abnormalities.

Many double-coated radiographic elements do not provide visually perceptible contrast to images of the heart when exposed to provide optimal contrast images of the lungs. this is,
This is because the radiographic element receives only about a tenth of the exposure in the heart region as it receives in the lung HaI region. Prior to the present invention, the technology had an extended tolerance.
The present invention has sought to meet the needs of radiologists for chest X-ray images that provide visually perceptible features in both the heart and lung image regions by providing radiographic elements (d latitude). Wide latitude radiographic elements typically use polydisperse silver halide emulsions to provide a lower average contrast and therefore a wider range of exposures separating minimum and maximum density exposures. Manufactured by

OBJECTS OF THE INVENTION It is an object of the present invention to provide a radiographic element whose X-ray absorption density is capable of increasing the information content of images of objects that vary over a wide range.

[Means for Solving the Problem] In one aspect, the present invention provides a transparent film support, first and second silver halide emulsion layer units coated on opposite sides of the film support, and the halogenated can reduce the crossover of electromagnetic radiation with wavelengths longer than 300 nm, which can form a latent image in the silver emulsion layer unit, to less than 10%;
The present invention is directed to a radiographic element comprising a cross-over reducing means that is bleached in less than 90 seconds during processing of the emulsion layer units. The above radiographic element is characterized in that the first silver halide emulsion layer unit has a density of 2.2 and 2.0, based on density measurements at 0.25 and 2.0 above the minimum density. and the second silver halide emulsion layer unit exhibits an average contrast of at least 2.5 based on density measurements at 0, 25 and 2.0 above minimum density. It is characterized by The contrast of the first silver halide emulsion layer unit is such that the second silver halide emulsion layer unit is arranged such that the first silver halide emulsion layer unit is present on both sides of the transparent support. unit by a first silver halide emulsion layer unit, and the contrast of the second silver halide emulsion layer unit is determined such that there are second silver halide emulsion layer units on both sides of the transparent support. The arrangement is determined by replacing the first silver halide emulsion layer unit with the second silver halide emulsion layer unit.

The dual coated radiographic elements of the present invention are capable of meeting the highest standards of the art with respect to sensitivity and sharpness.
g> provides the ability to create superimposed silver images. At the same time, radiographic elements can provide useful detailed image detail over a wide range of exposure levels within a single image.

This is accomplished by constructing the radiographic element with a transparent film support and first and second emulsion layers coated on opposite sides of the support. This allows transmission inspection of the silver image on the opposite side of the support after exposure and development.

between the emulsion layer units on opposite sides of the support, capable of forming a latent image on the silver halide emulsion layer unit;
The crossover of electromagnetic radiation with wavelengths longer than 10 nm
Means are provided to reduce the amount to less than %. In addition to having the ability to absorb longer wavelength radiation during imagewise exposure of the emulsion layer unit, the crossover reduction means decolorizes in less than 90 seconds during the development process.
ed) L7 must also have the ability to ensure that no visible interference is present to inspect the superimposed silver image.

The crossover reduction means reduces the crossover to less than 10%, preferably to less than 5%,
Optimally it is reduced to less than 3%. However, it should be noted that for the convenience of crossover measurements, the percentage crossover is meant to include "false crossovers," which are apparent crossovers that are actually the result of direct X-ray radiation absorption. be. That is, even when the crossover of longer wavelength radiation is completely eliminated, the measured crossover is still in the range of 1-2% and the χ that is directly absorbed by the emulsion furthest from the intensifying screen. It can contribute to line radiation. Crossover percentages are as described in US Pat. No. 4, Abbott et al.
No. 425,425 and No. 4,425,426.

In addition to the above requirements, the radiographic elements of the present invention differ from conventional dual-coated radiographic elements in that they require the first and second emulsion layer units to exhibit significantly different average contrasts. ing. The first silver halide emulsion layer unit is 2. It exhibits an average contrast of less than 0, while the second halogenated emulsion layer unit exhibits an average contrast of at least 2.5. The average contrast of the first silver halide emulsion layer unit and the average contrast of the second silver halide emulsion layer unit are at least 1.
It is preferable that they differ by 0. The best choice of average difference between the first silver halide emulsion layer unit and the second silver halide emulsion layer unit varies widely depending on the application served, but in many instances the first emulsion layer unit unit and the second emulsion layer unit are 0. 5-3.5, optimally 1.0-
Average contrast differences in the range of 2.5 are shown.

The first silver halide emulsion layer unit and the second silver halide emulsion layer unit may exhibit the same or different sensitivities. However, because lower average contrast emulsion layer units are typically made to provide detailed images in areas that receive the lowest exposure to X-ray radiation, lower average contrast emulsion layer units are less likely to be used than higher average contrast emulsion layer units. It is preferred to exhibit a photosensitivity at least equal to the photosensitivity. Lower average contrast emulsion layer units can exhibit sensitivities up to 10 times greater than the sensitivities of higher contrast emulsion layer units. It is generally preferred that the lower average contrast emulsion layer unit exhibit a sensitivity ranging from equal to the sensitivity of the higher contrast emulsion layer unit to four times greater.

Conventionally, sensitometric characterization of double-coated radiographic elements is the summation of the properties (density vs. vs. i.exposure) curve.

Therefore, contrast and other sensitivity measurements (minimum density,
In order to maintain the contrast and other sensitometric properties of the first silver halide emulsion layer unit (photosensitivity, maximum density, etc.), the first silver halide emulsion layer unit is 7f on both sides of the transparent support. ．． It is determined by replacing the second silver halide emulsion layer unit with the first silver halide emulsion layer unit so that the arrangement is as follows. The contrast 1 and other sensitometric properties of the second silver halide emulsion layer unit are determined by the contrast 1 and other sensitometric properties of the second silver halide emulsion layer unit.
: Determined in the same manner by replacing the first silver halide emulsion layer unit 1 with the second silver halide emulsion layer unit 1 so that the arrangement is such that there are 7 silver halide emulsion layer units 6 This specification The term "average contrast" as used in this book refers to the contrast determined by reference to emulsion layer unit characteristic curves at densities such as 0.25 above minimum density and 2.0 above minimum density. used for. The average contrast has a density difference of 1.75 between the two references of the characteristic curve. r. Divide by the logarithm of the difference in commercial light levels at point t (n light levels are meters-candle-seconds).

As used in the book, all references to photographic sensitivity 1 are to be understood as referring to comparisons of exposure levels at reference densities 1 and 0 above the minimum density. The sensitivity and average contrast characteristic curve reference points were chosen arbitrarily, but the selection was of the type used in the art. For non-typical characteristic curves (e.g., direct-bore imaging has an unusual curve shape), other sensitivity reference points can be selected. By reducing or eliminating crossover and using emulsion layer units that differ in average contrast and optionally in sensitivity, independent radiographic records can have their exposure levels differing by a factor of 10 (1.01 ogl!, where E (measured in meters-candle-seconds)] gives a better definition of the exposure difference over the area of 1.0 log Also referred to herein as a difference in 100 log relative exposure units. For example, a sensitivity difference of 0.3 1 ogE is a sensitivity difference of 30 log relative exposure units, and one emulsion layer unit is less than the other. It exhibits a photosensitivity twice that of emulsion 114 units 1.

The remaining features of the square coated radiographic elements of the present invention are that they may take any convenient conventional form. In a particularly preferred embodiment of the present invention, (1) the A cited in L.
U.S. Pat. No. 4,425 to Bott et al.
425 and 4+ 425,426, hereinafter referred to as T-Grain" emulsions, (2) are attributable to crossover levels of less than 10%, preferably less than 5%. sharpness level, (3) crossover reduction without emulsion desensitization or residual contamination, and (4)
) The advantages of rapid access processing are in addition to the above advantages.
Realized.

These additional benefits are explained by Dickerson et a.
In accordance with the teachings of U.S. Pat. No. 4,803,150 of
This can be achieved by selecting the features of the dual coated radiographic elements of the present invention. The following represents particular preferred selections of structural elements. Referring to FIG. 1, in assembly, a radiographic element 100 according to the present invention is positioned between a pair of photo-radiation intensifying screens 201 and 202. The radiographic element support is a translucent radiographic support element 1 which has an oval T1 tint and is capable of transmitting light exposed to it.
01 and optionally also transparent subbing layer units 103 and 105. The first and second opposing major surfaces 107 and 109 of the support bounded by the lower unit, respectively, have a cross-over reducing hydrophilic layer 1:
There are loid layers 111 and 113. Above the crossover reduction Ji 111 and 113 are optical recording latent image-forming silver halide emulsion layer units 115 and 117, respectively. Each of the emulsion layer units is defined by one or more hydrophilic colloid layers, including at least one silver halide emulsion layer. Emulsion layer units 115 and 1
Above 17 are optional hydrophilic colloid protective overcoats 119 and 121, respectively. All of the hydrophilic colloid layers are
Permeable to development processing solution.

In use, the assembly is imagewise exposed to X-ray radiation. The X-ray radiation is essentially absorbed by the intensifying screens 201 and 202, and the intensifying screens immediately emit light as a direct function of the xmn light. First of all, considering the light emitted by the intensifying screen 201, an optical recording latent image forming emulsion layer unit 115 is placed adjacent to this intensifying screen to receive the emitted light.

Due to the proximity of the intensifying screen 201 to the emulsion layer unit 115, only minimal light scattering occurs before latent image absorption occurs within this layer unit. The light radiation from the sensitizer 201 thus forms a sharp image within the emulsion layer unit 115.

However, not all of the light emitted by intensifying screen 201 is absorbed into emulsion layer unit 115.

This remaining light, if not absorbed elsewhere, would reach the remote emulsion layer unit I-117, resulting in a very unsharp image within this remote emulsion layer unit. The two crossover reduction layers 111 and 113 are connected to the intensifying screen 2
01 and the separate emulsion layer unit, and can capture and attenuate this remaining light.

These two layers thereby contribute to reducing the cross-over exposure of the emulsion layer unit 117 by the intensifying screen 201. In exactly the same manner, the sensitizer 202 produces a sharp image in the emulsion layer unit 117 and the light absorbing layer 1
11 and 113 similarly reduce the crossover i light of the emulsion layer unit 115 caused by the intensifying screen 202.

Following exposure to form the latent image, radiographic element 1
00 was removed from combination with intensifying screens 201 and 202 and dried to contact in less than 90 seconds.
o the touch) a rapid access processor capable of producing image-revealing radiographic elements, i.e., PR-X-
3,545,971 and Akio et al.
Al, European Patent Application Publication No. 248,390.

Since commercially used rapid access processors vary in their particular processing cycles and selection of processing solutions, preferred radiographic elements that meet the requirements of the present invention are those that when processed in less than 90 seconds with the following conditions: , it is specifically shown that it can be contacted and an image can be developed in a dry state up to 4.

Development Fixation at 35°C for 24 seconds Washing at 35°C for 20 seconds 10 seconds at 35°C and drying 6
20 seconds at 5°C (remaining time used for transportation between processing steps)
. The following developer is used in the development process. Hydroquinone 30g 1-phenyl-3-virazolidone 1.5 gKOH
21 gNaHCO37.5 g KzSO3 44.2
gNa2SzOs 1
2.6 gNaBr
35 g5-methylbenzotriazole 0.06
g Glutaraldehyde 4.9g Make up to 1 liter with water, pH 10.0, use the following fixing composition in the fixing step.

Ammonium thiosulfate (60%) sodium bisulfite boric acid acetic acid Aluminum sulfate Make up to 1 liter with water, pll 3.9-4.5.

Preferred radiographic elements of the present invention include (1) a substantial increase in emulsion layer units to achieve low crossover levels while achieving high hiding power and other known advantages of platelet grain emulsions; (2) in the interlayer unit to further reduce crossover to less than 10% with no emulsion desensitization and minimal or no residual dye stain; seeds or more particulate dyes, and (3) resulting uniform coatings, rapid access processing, and reduced or eliminated wet pressure sensitivity (
wet pressure sensitivity)
By using hydrophilic colloid swelling and coverage levels compatible with the above, the unique combination of advantages described above is possible. . Each of these features of the invention is 260
．． 0g 180. Og 25.0g 10.0g 8.0g will be described in detail below.

Each F layer unit contains a processing solution hydrophilic colloid and particulate dye. The total concentration of microcrystalline dye in the two underlying units is sufficient to reduce the crossover of the radiographic element to less than 10%.

This is selected such that the concentration of the dye gives the structure separating the emulsion layer units an optical density of at least 2.00 at the peak wavelength of the intensifying screen radiation of the electromagnetic radiation to which the emulsion layer units are responsive. . Although the dye can be distributed non-uniformly between the two sublayer units, each sublayer unit preferably contains sufficient dye to increase the optical density of the sublayer unit to 1.00. Using the latter value as a reference point, the dye can also be sensitized, since it is conventional practice to use a sensitized radiographic element combination in which the peak emulsion sensitivity matches the peak light emission by the intensifying screen. It will exhibit an fA degree of at least 1.00 at the wavelength of the paper's peak emission. Since neither intensifying screen radiation nor emulsion sensitivity is limited to a single wavelength, the use of particulate dyes that can provide densities of 1,000 or greater over the entire spectral region of important sensitivity and radiation. Preferably, particulate dyes containing a combination are selected. For radiographic elements used with blue radiation intensifying screens, such as those using calcium tungstate or thulium activated lanthanum oxybromide phosphors,
It is generally preferred that the particulate dye is selected to produce an optical density of at least 1.00 over the entire spectral region from 400 to 500 nm. For radiographic elements used with green radiation intensifying screens, such as those using rare earth (e.g., terbium) activated gadolinium oxysulfide or oxyhalide phosphors, particulate dyes cover the entire spectral range from 450 to 550 nm. Preferably it exhibits an optical density of at least 1.00 throughout. To the extent that the wavelength of the intensifying screen radiation or the sensitivity of the emulsion layer is limited, the spectral region over which the particulate dye must also absorb light effectively is relatively reduced.

A particulate dye optical density of 1,00, selected as above, is effective in reducing crossover to less than 10%, but the particulate dye density is reduced until radiographic element crossover is effectively eliminated. It is particularly recognized that it can be increased. For example, if the particulate dye concentration is 2. By increasing the particulate dye concentration to give a density of 0, the crossover is reduced to only 1%.

Accurate optical density selection can be accomplished by routine selection methods since there is a direct relationship between dye density and the optical density produced for a given dye or dye combination.

Because dyes vary widely in their extinction coefficients and absorption profiles, it is recognized that the weight or equimolar concentration of particulate dyes will vary from one dye or dye combination selection to the next.

The size of the dye particles is selected to facilitate dye coverage and rapid bleaching. In general, smaller pigment particles allow themselves more uniform coverage and more rapid decolorization. The pigment particles used in all examples were less than 10.04;
Preferably 1. It has an average diameter of less than O tna. There is no theoretical limit on the minimum size that dye particles can have. The dye particles are most conveniently in the form of particles larger than the dye is originally desired for use, which can be formed by crystallization from solution to a range of sizes down to about 0.01 m or less. If so, conventional methods for obtaining smaller particle sizes can be used, such as ball milling, roller milling, sand milling, and similar methods.

An important criterion in dye selection is its ability to remain in particulate form within the hydrophilic colloid layer of the radiographic element.

Hydrophilic colloids are Research Disc1os
are, Vol. 176. December 1978, I
tem 17643, Seetiori IX, νeh
icles and vehicles extend
The parent colloid layer is most commonly gelatin or gelatin derivatives (e.g., acetylated or phthalated), although it can take any of a variety of conventional forms, such as all of the forms described in RS. gelatin). To obtain adequate coating uniformity, the hydrophilic colloid should contain at least 1
It must be coated with a layer coverage of 0 .mu./drrr.

Any convenient larger coverage can be used so long as the total hydrophilic colloid coverage per side of the radiographic element does not exceed that compatible with rapid access processing. The hydrophilic colloid is used to shape the radiographic element layer.
~6, most typically 5.5-6. It is typically coated as an aqueous solution in the pH range of 0. The dyes selected for use in the practice of this invention are those p
It can remain in particulate form at H level.

Dyes that are ionic in nature, such as cyanine dyes, as well as dyes containing substituents that are ionically dissociated in the above pH range of the coating due to the chromophore formation mentioned above, are in particular examples of the present invention. It may be sufficiently insoluble to meet the requirements. However, there is generally no limit to the type of dye preferred for use in the practice of this invention. For example, dyes with sulfonic acid substituents are generally easy to dissolve to meet the requirements of the present invention. On the other hand, nonionic dyes with carboxylic acid groups (depending in some cases on the particular substitution position of the carboxylic acid group) are generally insoluble under aqueous acidic coating conditions. Specific dye selections can be made from known dye properties or at typical layer coating temperatures, such as 5.
5-6. This can be done by observing the solubility in the pl1 range of 0.

Preferred particulate pigments include merocyanine, oxonol,
Nonionic polymethine dyes including hemioxonol, styryl and arylidene dyes.

The merocyanine dye includes at least one basic heterocyclic nucleus and at least one acidic nucleus connected by a methine bond. The core may be linked by an even number of methine groups or may be a so-called "zeromethine" methine cyanine dye, with the methine linkages taking the form of double bonds between the methine groups contained in the core. Basic nuclei such as azolium or azinium nuclei include, for example, pyridinium, quinolinium, isoquinolinium, oxazolium, viradurium, vilorium, indolium, oxadiazolium, 3
Included are those derived from H- or lH-penzoindolium, pyrrolopyridinium, phenantothiazolium and acenaphthothiazolium quaternary salts. An example of a basic heterocyclic nucleus is the formula! or 11.

(+) (II) (wherein Z3 is oxazoline, oxazole, penzoxazole, naphthoxazole (for example, naphtho(2,1
-d) Oxazole, Nat[2,3-d]oxazole and Nat(1.2-d)oxazole), Oxadiazole, 2- or 4-pyridine, 2- or 4-quinoline, l- or 3-isoquinoline , benzoquinoline, l
Cyclic nuclei derived from basic heterocyclic nitrogen compounds such as H- or H-benzoindoles and pyrazoles, which may include hydroxy, halogens (e.g. fluoro, chloro, bromo and iodo), alkyl groups or substituted alkyl groups. groups (e.g. methyl, ethyl, probyl, isopropyl,
butyl, octyl, dodecyl, octadecyl, 2-hydroxyethyl, 2-cyanoethyl, and trifluoromethyl), aryl or substituted aryl groups (e.g. phenyl, 1-naphthyl, 2-naphthyl, 3-carboxyphenylinole and 4-biphenylyl) ), aralkyl groups (e.g. benzyl and phenethyl), alkoxy groups (e.g.
methoxy, ethoxy and isopropoxy), aryloxy groups (e.g. phenoxy and 1-naphthoxy), alkylthio groups (e.g. methylthio and ethylthio),
arylthio groups (e.g. phenylthio, P-tolylthio and 2-naphthylthio), methylenedioxy, cyano, 2-thenyl, styryl, ξ-no or substituted agono groups (
substituted on the ring by one or more of a wide variety of substituents, such as anilino, dimethylamino, diethylamino and morpholino), acyl groups (e.g. formyl, acetyl, henzoyl and benzenesulfonyl). Q′ represents the element necessary to complete the cyclic nucleus derived from basic heterocyclic nitrogen compounds such as pyrrole, virazole, indazole and pyrrolobilidine. R represents an alkyl, aryl, alkenyl or aralkyl group with or without substituents (e.g. carboxy, hydroxy, sulfo, alkoxy, sulfato, thiosulfato, phosphono, chloro and bromo substituents); Each L, when present, independently represents a substituted or unsubstituted methine group, such as a -CR'= group (R"
is hydrogen when the methine group is unsubstituted and most commonly represents an alkyl group of 1 to 4 carbon atoms or phenyl when the methine group is substituted. , and 9 is O or 1. ) In the merocyanine dye, one of the 12 salt viscous complex nuclei is bonded to the acidic 1-methylene nucleus through a methine bond (here, the methine group takes the form of -CRl'= above). The greater the number of methine groups that bind the nucleus in vorimethine dyes in general and merocyanine dyes in particular, the longer the absorption wavelength of the dye.

In the merocyanine dye, one of the basic heterocyclic nuclei described in (h) is bonded to the acidic ke-1-methylene nucleus through a methine bond as described above. The exemplified acid core satisfies (2).

(m) =. 7U~・”\G2 (wherein, GI is an alkyl group or a substituted alkyl group, an allyl group or a substituted aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a hydroxy group, an amino group or a substituted amino group (for example, The substituents represented can take the various forms described with respect to formulas (1) and (2).

G2 represents any one of the groups described for GI and also a cyano group, an alkyl or arylsulfonyl group, or a 110 group represented by 10-G', or Gt together with Q+ Became, 2
,4-oxazolidinediones (e.g., 3-ethyl-
2,4-oxazolidinedione), 2,4-thiazolidinedione (e.g., 3-methyl-2,4-thiazolidinedione), 2-thio-2,4-oxazolidinedione (e.g., 3-phenyl-2-thio2. 4-oxazolidinethione), rhotanines (e.g., 3-ethylrhodanine, 3-phenylrhodanine, 3-(3-dimethylaminoprobyl)rhodanine, and 3-carboxymethylrhodanine), hydantoins (e.g., 1.3-
diethylhydantoin and 3-ethyl-1-phenylhydantoin), 2-thiohydantoin [(e.g.,
1-ethyl-3-phenyl-2-thiohydantoin, 3
-hebutyl-l-phenyl-2-thiohydantoin, and arylsulfonyl-2-thiohydantoin), 2-
Birapurin-5-ones (e.g. 3-methyl-l-phenyl-2-birazolin-5-one and 3-methyl-1
-(4-carboxyphenyl)-2-birazoline-5-
on, 2-isoxazolin-5-ones (e.g. 3-
phenyl-2-inxaprin-5-one), 3.5-
Virazolidinediones (e.g. 1,2-jethyl-3
．． 5-Vyrazolidinedione and 1,2-diphenyl-3
．． 5-pyrazolidinedione), 1,3-indanedione, 1,3-dioxane-4,6-dione, 1,3-cyclohexanedione, barbylic acid (e.g. l-ethylbarbylic acid and 1. 3-diethylbarbituric acid) and 2-thiobarbituric acid (e.g. 1,3-diethyl-2-thiobarbituric acid and 1,3-bis(2
-methoxyethyl)-2-thiobarbylic acid) represents the elements necessary to complete a cyclic acidic nucleus, such as those derived from

Useful hemioxonol dyes exhibit a ketomethylene nucleus as shown in 2) and a nucleus as shown in 2).

(IV) where G3 and G4 are the same or different, alkyl, substituted alkyl, as indicated for the R ring substituents in formula I;
Aryl, substituted aryl, aralkyl; G3 and G4 together represent pyrrolidine, 3-pyrroline, viverizine, piperazine (e.g. 4-methylpiverazine and 4-phenylbiperazine), morpholine, 1,2,3
．． 4-tetrahydroquinoline, decahydroquinoline, 3
-Azabisic (3,2.2) nonane, indoline, azetidine and hemo; can complete ring systems derived from cyclic secondary amines, such as tonahydride and coazepine).

Exemplary oxonol dyes exhibit two getomethylene nuclei as shown in formula OI linked by one or more odd number of methine groups.

Useful arylidene dyes include a methine nucleus as shown in formula (2) and a nucleus as shown in formula (2) linked by a methine linkage as described above containing one or a larger odd number of methine groups. show.

(V) (wherein G1 and G4 are as defined above).

A particularly preferred class of oxonol dyes for use in the practice of this invention are the oxonol dyes described in Factor and Diehl, European Patent Application No. 299.435. These oxonol dyes satisfy formula (2).

(Vl) (wherein R' and Rt each represent an alkyl group of 1 to 5 carbon atoms).

Particularly preferred f! for use in the practice of this invention! l! The arylidene dyes of the same class are Dimu and l'acLor.
It is an arylidene dye described in European Patent Application Publication Nos. 274,723 and 294.461. These Arylidene color chords satisfy the formula (■).

(■) (wherein A is 2-birazolin-5ones, rhodanines, hydantoins, 2-thiohydantoins, 4
- a carboxyphenyl or sulfonate selected from the group consisting of thiohydantoins, 2,4-oxazolidinediones, 2-thio-2,4-oxazolidinediones, isoxazolinones, barbiturates, 2-thiobarbic acids and indanediones; ξ represents a substituted or unsubstituted acidic nucleus having a dophenyl substituent, R represents hydrogen, an alkyl group of 1 to 4 carbon atoms or benzyl, Rl and R2 each independently represent alkyl or aryl; or represents an atomic group necessary to complete a juloliden ring together with R', Rh, N and the carbon atom to which they are bonded, R3 represents H1 alkyl or aryl, R% and Rh are each independently,
H or RS together with Rl or R
Together with R2, h represents an elementary Y group necessary to complete a 5-membered or 6-membered ring, respectively, and m is O or 1T (oru).

Also contemplated are oxinazole and oxazoline pyrazolone cyanine particulate dyes. Particulate dye of formula (2) is a typical example.

(■) 0? In (■), "(, 1C. and R. each independently represent substituted or unsubstituted alkyl, or substituted or unsubstituted aryl, or together represent substituted or unsubstituted aryl. 5 Represents the necessary atomic group to complete a one- or six-membered ring.

R3 and R4 each independently represent H, substituted or unsubstituted alkyl, monomer or unsubstituted aryl, CO■
11, or NII SO, R. represents. r<,
is I], substituted or unsubstituted alkyl, substituted or J1-substituted aryl, carboxyle], [i.e.
COOI? (wherein R is rfl-like or unsubstituted alkyl)], or substituted or unsubstituted acyl,
R6 and R7 are each independently substituted or unsubstituted alkyl, or substituted or unsubstituted aryl,
And n is 1 or 2. R. is substituted or unsubstituted alkyl, or is part of a double bond between R and the ring carbon atom to which R2 is attached. At least one of the aryl rings of the dye molecule is CO2+1 or NIISO
It must have at least l substituents that are zR*.

Also contemplated are oxazole and oxazoline benzoylacetonitrile merocyanine particulate dyes. Particulate dye of formula (2) is a typical example.

In formula ■, R. ,R. ．． R,,R. , R., and R.
are respectively substituted or unsubstituted alkyl or substituted or unsubstituted aryl, preferably substituted or unsubstituted alkyl of 1 to 6 carbon atoms, or 6 to 12
It may be substituted or unsubstituted aryl of 5 carbon atoms. R. may be substituted or unsubstituted alkyl of 1 to 6 carbon atoms. The alkyl or aryl group is
Substituted with any number of substituents, other than those such as sulfo substituents, which tend to increase the solubility of the dye to such an extent that it becomes soluble in the coating pl+ good. Examples of useful substituents include halogen, alkoxy, ester groups, amido, acyl, and alkyl groups.

Examples of alkyl groups include methyl, ethyl, n-propyl,
Includes isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl or isohexyl. Examples of aryl groups include phenyl, naphthyl, anthracenyl, pyridyl and styryl.

R1 and R2 also together represent the atomic group necessary to complete a substituted or unsubstituted 5-1 or 6-membered ring, such as phenyl, naphthyl, pyridyl, cyclohexyl, dihydronaphthyl or acenaphthyl. This ring may be substituted with W substituents other than those such as sulfo substituents which tend to increase the solubility of the dye such that it becomes soluble in the coating pl+. Examples of useful substituents include halogen, alkyl, alkoxy, ester, ado, acyl and alkylamino.

Useful bleaching particulate dyes include a wide range of cyanines, merocyanines, oxonols, arylidenes (i.e. merostyryls), anthraquinones, triphenylmethines, ab,
It can be found among azomethine and other pigments. Such dyes are indicated by those satisfying the criteria of Formula X.

(X) CD-(A),)-X.

(In the formula, D is a light-absorbing compound of a chromophore, which may or may not consist of an aromatic ring if y is 0, or an aromatic ring if y is 0. , A is an aromatic ring directly or indirectly bonded to D,
X is a substituent having an ionizable moiety on either the aromatic ring moiety of A or D, y is 0-4, and n is 1-7). This dye has a p of 6 or less.
It is substantially water-insoluble at pH 11 and substantially water-soluble at pH 8 or above.

The aggregation of the particulate dyes can be accomplished according to methods known in the art for the aggregation of dyes of the same type.

For example, “The Cyanine Dyes and
Related Compounds”,Franc
Interscience P by es llamer
Those who are familiar with the method of dye coalescence disclosed by J. Ublishers, 1964, can easily synthesize cyanine, merocyanine, merostyryl and other vorimethine dyes. Oxonol, anthraquinone, triphenylmedine, ab and azomethine dyes are known dyes or substitutional variations of these types of known dyes, and known methods of shaping these types of dyes. Alternatively, it can be synthesized by obvious modifications of known methods.

Examples of particulate dyes that can be used in the practice of the present invention include the following Φ.

GoΣ Earth dog general structure: CO2H 4.62 CH3 C○2Et CO2H CO2H 3,90? ■25 fip II Table 2 Σ plan. Elleni 2-2 (-1・--zo↓back l
豐l2 yo begging - arneepi 4 Otsu L3 general setup: general setup'? i: 通. L 2 included table n-C61113So2N11 CH3SO2NH CI13S02NB H CH3445 C3H7446 n-C6H13447 CH3449 7 32 7.86 7.6 6.5 3.86 Younger brother! ! L table. ? ii2 Hisuya E2-j・I, j-7 Hiotoko 2 1Li Ichiotoshiki Soku general disaster 1rA + & t i-Kan: 舅” Jinyui-Pro2CCH2i-Pro2CCH2C2H5C
F3CH202CCH2 i-Pr02CCH2i-Pro2CCH3C2H5C
F3CH202CCH2 3.5 4.27 4.2 4.25 Dye 16 CH3 H R4). -max cmax (x 104) (methanol) Co2H 450 7.4 (methanol) Spring X table/< )u 9 -Z 2) L7fJi. ．． ) 鴴'
J -'/-4 7 (L- 7'31 FPt misfortune: General side i2i: ?XL & Dye 20 K2 MeOEtSO2NH MeOEt SO2N1{ MeSO2Nl{ MeSO2NH MeOEtS02NH Et SO:z Listen EtSO2 listening MeO EtSO2Nl{ R2 Et: Me Et Et MeOEt CH2PhCO2H MeOEt MeOEt Et Me MeOEt R3 MeOEhiSo21m MeS02N'H MeOEt SO Z between HexSO2PrH MeS02N'H P r SO2Till Prso2Nkl P r SO2KH Me S Between OZ Me S Between OZ MeOEt SO 2 Fn1 RI HexSO2Ml{ MeOEt SO2 listening Me SOZ Between CO2H CO2H EtOEtOEtSO2NH EtOEtOEtSO2Nl{ Between P r S O R2 MeOEt MeOEt CH2PhCO2H Me Me Me Et Et Me Et Et R3 Me502NN{ ElexSO%H MeSO2tiH MeSO2[{ MeSO2 vs. P r SO 2 vs. Me SO2N1 { P r SOZ vs. Me502N'H Between MeS02zts02 Between EtSOzMeSO2 NE CO2H MeS02NH Bu S O2 1 NHS02(CH2)3CH3 Younger brother- ■Top soil Q] ■Table I'' 2=--Leede 1 Do (31 me+ and CH3 COOE set COOEt 11 CCI{314 C2Hs H n-C4H9H C}T3H i-C3H7°赫2°H3 C}13H C2Hs H n-C4H9H CH31 CH31 COOC2H51 CH3 1 2 3 5 2 3.5 2 3I5 O 471 0 475 0 508 0 430 0 457 0 475 0 477 4.75 4.50 5.20 3,34 3 78 4.55 4.92 Anin U ?- C3H7° Stomach 2H i-C3H,OCQH■CH3 E~C3H70CCH2H 2 3,. 5 0 420 3.622
3,5 0 434 3.251
4 0 420 3.94! CH2C}{3 1 CH2CH3 CO2H kl2UH3 5.56 4,83 6,22 4,58 4,54 5,36 1 CO2H ゝ”Co2H ゝ''Co2H ΣTable i CO2H T CO2H CH3 ?■L table oxo The RIR2 dye can be added directly to the iJLoid as a particulate solid, or it can be converted to a particulate solid after it is added to the parent colloid. One example of a method is to dissolve a non-water soluble dye in a non-aqueous solvent. The dye solution is mixed with a water ttm aqueous colloid, and then the hydrophilic colloid is noodled.
ling) and when washed (said Research
Disclosure, ILem 17643, S
(see section If), the dye solvent is removed leaving the particulate dye dispersed in the water colloid. Thus, any water-insoluble dye that is soluble in a water-miscible organic solvent is suitable as a particulate dye in the practice of this invention, as long as the dye can be bleached under the processing conditions, e.g., at alkaline pH levels. Can be used.

Specific examples of water-miscible organic solvents contemplated are methanol,
Ethyl acetate, cyclohexanone, methyl ethyl ketone,
2-(2-ptoxyethoxy)ethyl acetate, triethyl phosphate, methyl acetate, acetone, ethanol and dimethylformamide. Dyes preferred for use with these solvents are sulfonamide-substituted arylidene dyes, with the examples listed in Tables IIA and II being particularly preferred.

In addition to being in particulate form and meeting the above optical density requirements, the dyes used in the underlying unit must be substantially decolorized during processing. The term "substantially bleached" means that the dye in the underlying unit, when fully processed under the reference processing conditions described above, reduces the minimum density of the radiographic element to 0.00000. Used to mean increasing no more than 1, preferably no more than 0.05. As shown in the Examples below, preferred particulate dyes do not produce a significant increase in the optical density of fully processed radiographic elements of the invention.

As previously indicated, it is specifically contemplated that UV absorbers are used, preferably blended with pigments in each of crossover reduction layers 111 and 113. Any conventional UV absorber can be used for this purpose. Representative useful UV absorbers are described in Research, supra.
h Dtsclosure, Item 18431,
Section V, or Research D above
isclosure, Ites+ 17643+ Se
This is disclosed in ction (C). Preferred UV absorbers are those that exhibit minimal absorption in the visible part of the spectrum or are bleached during processing, similar to the crossover reduction layer.

Above the lower layer unit on each major surface of the support, at least one additional hydrophilic colloid layer, in particular a spectrally sensitized silver bromide or silver bromoiodide tabular grain emulsion layer. There is at least one halide emulsion layer unit. At least 50% (preferably at least 70%, optimally at least 90%) of the total grain projected area of the tabular grain emulsion is 0.
．． dominated by plate-like particles having a thickness of less than 3 ttn (preferably less than 0.24) and an average aspect ratio of greater than 5:1 (preferably greater than 8:1, optimally of at least 12:1) . Preferred tabular grain silver bromide and silver bromoiodide emulsions are Wilgus eLa
No. 4,434,226, Kofron
et al., U.S. Pat. No. 4,439,530, Abb.
U.S. Pat. Nos. 4,425,425 and 4,425,426 to Ott at al, U.S. Pat. No. 4,414,304 to Dickerson, U.S. Pat. No. 4,425,501 to Maskasky and Dickers
No. 4,520,098, issued to U.S. Pat.

For the purposes of both achieving maximum image sensitivity and minimizing crossover, platelet grain emulsions are substantially optimally spectrally sensitized. That is, sufficient spectral sensitizing dye is adsorbed to the emulsion grain surfaces to achieve at least 60% of the maximum achievable sensitivity from the emulsion under the intended exposure conditions. It is known that optimal spectral sensitization is achieved with a single layer coating of about 25-100% or more of the total available surface area represented by the particles. Preferred dyes for spectral sensitization include cyanine, merocyanine, hemicyanine,
vorimethine dyes such as hemioxonol and merostyryl dyes. A particular example of a spectral sensitizing dye and its use to sensitize platelet grain emulsions is κofr
No. 4,439,520 to et al. Although not a necessary feature of the invention, platelet grain emulsions are rarely used in practice without chemical sensitization. Any convenient chemical sensitization of platelet grain emulsions can be performed. The platelet grain emulsions are preferably substantially optimally (as defined above) chemically and spectrally sensitized. Useful chemical sensitizations, including selected site epitaxial textures as well as noble metal (e.g., gold) sensitization and chalcogen (e.g., sulfur and/or selenium) sensitization, are cited above for tabular grain emulsions. Patents, especially Ko
as disclosed in the fron et al and Maskasky patents.

In addition to the grains and spectral sensitizing dyes, the emulsion layer may contain as a vehicle one or a combination of any of the various conventional curable hydrophilic colloids, alone or in vehicle-spreading agents such as latex and the like. It may be included in combination with other agents. The vehicle and vehicle spreading agent of the emulsion layer unit 7} may be the same as that of the interlayer unit. Bexhil and Bexhil spreading agents are described in the above-mentioned Research
Disclosure, Item 17643+ Se
ctton IX. A particularly preferred hydrophilic colloid is gelatin or a gelatin derivative.

The coverage of the emulsion layer is selected to provide the desired maximum density level in processing. For radiography, the maximum density level is generally in the range of about 3-4, although specific applications may require higher or lower density levels. The silver images produced on opposite sides of the support are superimposed during inspection so that the observed optical density is the sum of the optical densities provided by each emulsion layer unit. Assuming equal silver coverage on opposite major surfaces of the support, each emulsion layer unit has a silver coverage of about 18 to 30 μ/dm", preferably 21
It should contain a silver coverage of ˜27 μ/d.

It is a conventional method to protect emulsion layers from damage by providing an overcoat layer. The overcoat layer can be formed from the same vehicles and vehicle spreading agents as disclosed above in connection with the emulsion layer. The outer covering layer is most commonly gelatin or a gelatin derivative.

wet pressure sensitivity
The total aqueous colloid coverage on each major surface of the support should be at least 35 μ/dllffi to avoid
Must be. It is the total hydrophilic colloid coverage on each surface of the support and not, as has been commonly believed, simply the hydrophilic colloid coverage in each silver halide emulsion layer that controls its wetting pressure sensitivity. These are the observation results of the present invention. Thus, 10 mg/dta in the interlayer unit for coating uniformity! of hydrophilic colloid is required and the emulsion layer can contain as little as 20 μ/d of hydrophilic colloid.

To allow rapid access processing of radiographic elements,
The total hydrophilic coating coverage on each major surface of the support was 65/
da", preferably less than 55 .mu./dm", and the hydrophilic colloid layer must be substantially completely precured. Substantially fully precured means that the processing solution permeable hydrophilic colloid layers are precured in an amount sufficient to reduce the swelling of these layers to less than 300%. Percent swelling is determined by the following reference swelling determination method: (a) incubating the radiographic element at 38° C. and 50% relative humidity for 3 days; (b) measuring layer thickness; (C) The radiographic element is immersed in distilled water at 21''C for 3 minutes and (d) the percent change in layer thickness compared to the layer thickness measured in step (b) is determined.

This reference method for measuring precure is the Dicker
No. 4,414,304 to Son. Using this reference method, it is preferred that the hydrophilic colloid layer is sufficiently precured and the swelling is reduced to less than 200% under the above test conditions.

Any conventional transparent radiographic element support can be used. Research Disclosure cited above
re+Item 17643 Section XrV
Transparent film supports, such as all of those disclosed in , are all contemplated. A preferred transparent film support is a polyester support because of its excellent dimensional stability. Poly(ethylene terephthalate) is a particularly preferred polyester film support. The support is typically blue colored to aid in inspection of the image pattern. Blue anthracene dyes are typically used for this purpose. In addition to the film itself, the support is usually formed with a subbing layer on its major surface to receive the sublayer unit. Further details of the support construction, including exemplary anthracene dyes and subbing layers, can be found in Research Disclosure, cited above.
See Item 18431 Section X II.

In addition to the features of the radiographic elements of the invention described above, radiographic elements. It is recognized that elements can and will include additional conventional features in most practical applications. Research Di cited above
sclosure, Item 18431, the emulsion layer contains stabilizers, anticapri agents, and anti-kink agents of the type described in Section II.
tikinking agents) and the jacket layer may include any of a variety of known additives of the type described in Section IV.

The outermost layer of the radiographic element may also contain Res
EARCH DISCLOSURE, Item 17
643 Sectton XVI may be included. Research
With further reference to Disclosure, Ttea+ 17643, Section X I Coating Aids, Se
ctionX■ plasticizers and lubricants, and Section
The inclusion of an antistatic layer of n X III in each case is also contemplated.

(Examples) The present invention will be explained in more detail with reference to the following examples.

cliff The following intensifying screen was used.

Banou-Kei This is a Permu thane coated on a white pigmented polyester support.
Comprising a terbium-activated gadolinium oxysulfide phosphor with a medium particle size of 1 tna in a Tl'' polyurethane binder with a total phosphor coverage of 7.0
g/d-, and the phosphor to binder ratio is 15:1. This intensifying screen has a composition and structure comparable to that of commercially available intermediate resolution intensifying screens. ．． This is Permu Lhan coated on a white pigmented polyester support.
Consisting of terbium-activated gadolinium oxysulfide phosphor with a medium particle size of 7μ in an eTl'' polyurethane binder with a total phosphor coverage of 5.9g
/d1, the phosphor to binder ratio is l5:1, and the yellow dye and carbon in a weight ratio of 100:1.
Contains 017,535% heavy weight.

This intensifying screen has a composition and structure comparable to that of commercially available high resolution intensifying screens. It consists of a terbium-activated gadolinium oxysulfide phosphor with a medium particle size of 51M in a Permuthane" polyurethane binder coated on a blue-tinted transparent polyester support, with a total phosphor coverage of 3.8 g/
dm'' with a phosphor to binder ratio of 21:1 and a carbon content of 0.0015%.

An assembly consisting of a double-coated radiographic element sandwiched between a pair of intensifying screens was exposed in each case as follows. Assemble the assembly, change the current (-A) or time, and do 3ffl! l
3-phase Picker with filtration up to + Aluminum
Medical (Model VTX-650)TI'
Exposure was made to 70KVp X-ray radiation using a 1X-ray unit. Sensitometric grading in exposure was performed by using a 21-increment (0.11 ogE) aluminum step wedge of varying thickness. Myu Valley Ill E+l. LC LXOA (E+l.
HC radiographic element A was a double coated radiographic element exhibiting near zero crossover.

Radiographic element A has dye 56 and dye 5 on each side thereof.
Gelatin (containing 320 μ/g) in a 1:l weight ratio mixture of 9
It was constructed from a low crossover support composite (LXO) consisting of a blue colored polyester support coated with a crossover reducing layer consisting of 1.6 g/ryf).

Low contrast (LC) and high contrast (HC) emulsion layers were coated over the crossover reduction layer on opposite sides of the support. Both emulsions are green sensitized high aspect ratio tabular grain silver halide emulsions, the term "high aspect ratio" being used in U.S. Pat.
No. 425, at least 50% of the total grain projected area is 0.425. has a thickness of less than 3 tn+;
Used to require that the grains be occupied by platelet grains with an average aspect ratio greater than 8:1. Low contrast emulsions have an average grain size of 3. The first emulsion has an average grain thickness of 0.13μ and an average grain size of 1.2.
n and the second emulsion exhibiting an average grain thickness of 0.131 = 1
(Silver ratio) It was a blend. The high contrast emulsion exhibited an average grain size of 1.7-m and an average grain thickness of 0.13 m. High contrast emulsions exhibited less polydispersity than low contrast emulsions. Both the high and low contrast emulsions are anhydrous 5,5-dichloro-9-ethyl-3.
It was spectrally sensitized with 3'-bis(3-sulfopropyl)monoxacarbocyanine hydroxide 4QOmg/Ag mole and then with potassium iodide 300 .mu./Ag mole.

Each emulsion layer has a silver coverage of 2.428/n'? and coated with gelatin coverage of 3.22 g/n. Protective gelatin W! ! (0.69 g/ryf) was coated on top of the emulsion layer. Each gelatin-containing layer is coated with 1 of the total gelatin.
% of bis(vinylsulfonylmethyl)ether.

When coated as above, but symmetrically, on both sides of the support, except for emulsion HC, and coated using X pairs of intensifying screens, emulsion LC has a relative log sensitivity of 9
8 and an average contrast of 1.8. Similarly,
When coated symmetrically with the exception of emulsion LC, emulsion HC exhibited a relative log sensitivity of 85 and an average contrast of 3.0.

Thus, these emulsions have an average contrast of 1.
2 difference, the sensitivity is 13 (or 0 in relative logarithmic sensitivity units)
．． 131ogE).

Element A is described in US Pat. No. 4,4 by Abbott at al.
When tested for crossover as described in No. 25,425, it showed 2% crossover. Radiographic Element B was a conventional double coated radiographic element with wide exposure latitude.

Radiographic Element B was constructed from a blue-colored polyester support lacking the crossover reducing layer of Radiographic Element A. The same emulsion layer (L) was coated on the opposite side of the support. The emulsion used was a green-sensitized polydisperse deep silver iodide emulsion. Since this emulsion is not a high aspect ratio tabular grain emulsion and therefore requires substantially less dye for optimal sensitization, only 42 mg/Ag mole was required in Element A. The same spectral sensitizing dye was used. Each emulsion layer has a silver coverage of 2.62 g/n? and coated to give a gelatin coverage of 2.85 g/rrf.

Protected Gelatin M (0.70 g/n{) was coated on top of the emulsion layer. Each of the layers was coated with 0.0% total gelatin. Cured with bis(vinylsulfonylmethyl)ether at 5%.

When coated as described above, the film exhibited a relative 1ogE sensitivity of 80 and an average contrast of 1.6 using X pairs of intensifying screens.

Element B is described in US Pat. No. 4,4 by Abbott et al.
When tested for crossover as described in No. 25,425, it showed a crossover of 25%.
showed that.

．． Ce01(Em.MC IIXOc(Em.MC)
Radiographic element C was a conventional double coated radiographic element of the type sometimes used for chest cavity examinations.

Radiographic element C has a medium contrast emulsion layer (MC)
was used and the silver coverage of each emulsion layer was reduced to 1.93 g/vo.

When coating using X pairs of intensifying screens as described above,
The film exhibited a relative 1ogE sensitivity of 80 and an average contrast of 2.6.

Element C is described in U.S. Pat. No. 4.4 of Abbott et at.
When tested for crossover as described in No. 25,425, it showed 30% crossover.

The radiographic element D is sometimes used for chest cavity examination in subjects with low chest density, i.e. children or adults of slender build. These were the types of conventional high aspect ratio platelet grain double coated radiographic elements. Radiographic Element D is a radiographic element except that a crossover reducing layer was not coated on the film support and a high contrast emulsion (HC) similar to that used in Radiographic Element A was coated on both sides of the support. I took precautions like A.

When coating using X pairs of intensifying screens as described above,
The film exhibited a relative 1ogE sensitivity of 80 and an average contrast of 2.9.

Element C is described in US Pat. No. 4,4 by Abbott et al.
When tested for crossover as described in No. 25,425, it showed 20% crossover.

Processing This film is available commercially from Kodak RP.
X-Omat (Model 1 6B)" rapid access processing machine for 90 seconds as described below.

Development: 20 seconds at 35°C Fixation: 12 seconds at 35°C Washing: 8 seconds at 35°C and drying: 20 seconds at 65°C (however, the remaining time is used for transportation between processing steps) )
. The following developer is used in the development process. Hydroquinone 30gl-phenyl-3-virazolidone 1.5gKOj1
21gNatlCO37.5g K! So, l44.2g NazSzOs 12.
6 gNaBr 35
g5-Methylbenzotriazole 0.06g Glutaraldehyde 4.9g Make up to 1 liter with water, pH 10.0, The following fixing composition is used in the fixing step.

Ammonium thiosulfate (60%) 260.0
g Sodium bisulfite 180.0 g Boric acid 25.0 g Acetic acid 10.0 g Al≧Nium sulfate 8. Make up to 1 liter with Og water, pl 13.9-4.5.

The optical density is expressed as the diffuse density measured by an X-rite MODel 310" densitometer, which is the AN
Corrected to SI standard pll2.19, National
Bureau of Standards calibration step tablet
ablet). A characteristic curve (1 degree vs. 1 og E) was plotted for each processed radiographic element. The average gradient shown in Table X below under the heading of contrast was determined from the characteristic curve at 0.25 and 2.0 above the minimum density.

As shown in Table 2, between the pair of intensifying screens, element A (which satisfies the requirements of the present invention), control elements, elements B and C are placed between the pair of intensifying screens.
and D, respectively, to form two assemblies.

Table X■ [. Z(Em.LC)LXOA(Effi.HC)X
1. '5 100 10011. Z
(Em.L)HXOB(EIIIl.L)X 1.
6 100 60Iff. X(Ea+.L)
HXOB(Ea+.L)Z 1.6 10
0 60IV. X(Em.L)t{XQB(E
a+. L)X 1.6 100 60
V. Z(Em.MC)HXOC(En.MC)Z
2.6 115 20VI. Z(Em
, MC) IIXOD (Effi.HC) Z 2.
9 130 20 ■. Z (Em.FLC)
LXOE(Em, SHC)X 2.5 115
40■, Z (Em, SHC) LXOE (h.
FLC')X 1.5 69 266
It is clear from Table X■ that assemblies ■ through ■ all exhibited similar average contrast when exposed between pairs of intensifying screens. The relative lung contrast, listed as 100, was chosen as the contrast corresponding to a density of 1.8, which is a commonly accepted density for reading lung features in radiographs. The heart then generally absorbs about 10 times the X-ray radiation absorbed by the lungs, so that about (Example) (Control Example) (Control Example) ( CONTROL EXAMPLE) (CONTROL EXAMPLE) (CONTROL EXAMPLE) (EXAMPLE) (EXAMPLE) The relative cardiac contrast was set to 1.0 to reflect the fact that only a tenth reaches the radiographic elements of the cardiac region.
0 IogE was fixed as the contrast corresponding to low exposure level. In the cardiac image area, the assembly ■
However, for the purpose of comparing the contrast in the cardiac image area of various assemblies, the cardiac image area of the assemblage
The relative contrast was 0.00. Relative heart H of assembly ■～■
Comparing the area contrast with that of group I, group ■
It was observed that ~■ gave only 60% of the contrast obtained by Assembly 1. Cardiac region contrast was so low in the control set that it required skilled observation to distinguish significant image features, but with set I containing the dual-coated radiographic elements of the present invention. The greater cardiac region relative contrast afforded was clearly discernible with less viewing effort. The assemblies JT,I[I and ■ show that intensifying screen manipulation was ineffective in affecting the contrast observed using conventional wide latitude radiographic elements.

Sensitized V and ■ are clearly observed in the cardiac region using conventional radiographic films of the type that are sometimes used for chest cavity examinations but are not specifically designed for this use. In order to show poor image contrast,
■Included in the table. Radiographic elements C and D, which have a relative sensitivity of only 20 in the cardiac region, clearly have limited utility in chest cavity examinations in the cardiac region.

Double-coated radiographic elements exhibiting a crossover level of less than 10% and at least 2 times, preferably 2 to 10 times, and optimally 2 to 4 times the sensitivity of the second emulsion layer unit on the opposite side of the support. Related research has shown that the first emulsion layer unit on one side of the transparent film support, which is twice as large, exhibits different average contrasts when used in conjunction with different intensifying screen pair combinations. It was shown in From these related studies, it was found that by replacing film B with film A in either assembly ■ or ■, higher average con
It was concluded that this results in higher contrast in the last and possibly cardiac image regions.

Assemblies ■ and ■ were developed by Dickerson et al (I
II) has been designed to demonstrate further advantages that can be realized by combining the teachings of this specification.

=E −1 (Em.FLC)LXOE(E
m. SHC radiographic element E was a double coated radiographic element exhibiting near zero crossover.

Radiographic Element E was constructed from the same low crossover support composite (LXO) as that of Element A above.

Fast low contrast (FLC) and slow high contrast (SHC) emulsion layers were coated over the crossover reduction layer on opposite sides of the support. Both emulsions were green sensitized high aspect ratio tabular grain silver bromide emulsions and were coated in the same manner as the emulsion layer of Element 8.

Emulsion SHC using emulsion FLC coated on both sides of the support
When coated symmetrically, using X pairs of intensifying screens, emulsion FLC exhibited a relative log sensitivity of 113 and an average contrast of 1.98. Similarly, when coated symmetrically with the exception of emulsion FLC, emulsion SHC exhibited a relative log sensitivity of 69 and an average contrast of 2.61. These emulsions thus differ in average contrast by 0.63, while in sensitivity they differ by 44 relative log sensitivity units (or 0.44
The difference was about 1ogE).

Element E is described in US Pat. No. 4,4 by Abbott et al.
When tested for crossover as described in No. 25,425, it showed 2% crossover.

Referring to table It is clear that results comparable to those obtained with Control Film C were obtained, with the exception that a change was observed. When the film was reversed, the contrast in the lungs decreased somewhat, but remained well within the range to obtain useful information from the lung image area. At the same time, the relative contrast in the heart region increased to 266. So,
This combination clearly outperforms all others in Table XI for obtaining image information from the heart W& region.

The above comparison provides a striking illustration of the benefits that radiologists can realize from the present invention. The present invention provides the radiographer with improved diagnosability over a wide range of radiographic element exposures in studying a single radiographic image.

[Effects of the present invention]

The dual-coated radiographic elements of the present invention produce greater than a 50% increase in contrast in the heart region while providing contrast in the lung region similar to conventional wide latitude double-coated radiographic elements. It is shown that it can be obtained.

To that end, the present invention represents a significant advance in meeting the diagnostic needs of medical radiologists. Furthermore, although the present invention has been shown to simultaneously obtain visible and useful detailed images of both the heart and lung regions, the advantage of the present invention is that the x-ray radiation absorption capacity of the examined object is Needless to say, it can be applied to any changing image forming application.

[Brief explanation of drawings]

FIG. 1 is a diagrammatic illustration of an assembly consisting of a double coated radiographic element sandwiched between two intensifying screens. 100... Radiographic element, 101... Support element, 103... Undercoat unit, 105... Undercoat unit, 107... Main support surface, 109...
Main support surface, 111... Crossover reducing layer, 113... Crossover reducing layer, 115... Emulsion layer unit, 117... Emulsion layer unit, 119... Protective jacket, 121... - Protective outer cover, 201... Intensifying screen, 202...
Intensifying screen. F/(3.

Claims (1)

[Scope of Claims] 1. A transparent film support capable of forming a latent image on the first and second silver halide emulsion layer units coated on opposite sides of the film support and the silver halide emulsion layer unit;
In a radiographic element comprising means for reducing the crossover of electromagnetic radiation of wavelengths longer than 300 nm to less than 10%, the crossover reducing means being bleached in less than 90 seconds during processing of the emulsion layer unit. , the first silver halide emulsion layer unit has a minimum density of 0
．． The second silver halide emulsion layer unit exhibits an average contrast of less than 2.0 based on density measurements at 0.25 and 2.0 above the minimum density.
The contrast of the first silver halide emulsion layer unit is at least 2.5, based on density measurements at The second silver halide emulsion layer unit is replaced with the first silver halide emulsion layer unit so that the arrangement is such that, and the contrast of the second silver halide emulsion layer unit is
The first silver halide emulsion layer unit is replaced with a second silver halide emulsion layer unit so that the second silver halide emulsion layer unit is present on both sides of the transparent support. Characteristic radiographic elements.