Silver halide light-sensitive photographic material with enhanced image quality for rapid processing applications in mammography

A silver halide light-sensitive photographic material for applications in the field of mammography is disclosed which has an improved diagnostic value by an enhanced sharpness. The silver halide crystals to be used in the said material show a fog level, a toe contrast and an overall contrast that is, like the image quality, substantially uneffected by the processing conditions. The coating amount of silver halide crystals in the emulsion layer can be reduced to such an amount that an archivability of from 10 to 20 years can be assured in normal storage conditions. The X-ray material is suitable for rapid processing, without loss in sensitivity, within processing cycles of 45 or 38 seconds, wherein hardener-free processing solutions can be used.

DESCRIPTION 
1. Field of the Invention 
This invention relates to a silver halide photographic light-sensitive 
material suitable for rapid processing applications in the field of 
mammography. 
2. Background of the Invention 
In medical radiography the direct exposure technique is used in 
mammographic applications, wherein the radiation pattern leaving the 
patient's breast is registered directly on a film with the use of an 
intensifying screen. 
No other area of medical X-ray applications demands such a level of 
contrast and spatial resolution as produced in quality mammography. This 
explains why single-sided films are used in this application. 
The success of mammography, whether for screening or diagnosis, depends on 
the production of high-quality, low-dose images. Image quality determines 
the accuracy with wich the various structures are recorded and 
abnormalities detected. For mammography, films high in contrast are 
preferred. Most of the mammographic films have a high overall-contrast but 
also the toe contrast, i.e. the contrast in the region of the lightest 
areas on the film is important. Dense structures in the breast give rise 
to pale areas on the mammograms. When the degree of contrast is low in 
this area, i.e. well below the linear portion of the characteristic curve, 
this area is underexposed. The degree of contrast that can be obtained in 
this low density area, would be increased, if the film density level is 
increased within the linear portion of the characteristic curve. This can 
be achieved by increasing exposure (mAs) or X-ray tube potential (kV). In 
this way, dense structures in the breast would be less often underexposed, 
but there are some disadvantages. By increasing the mAs, less dense breast 
structures may become overexposed, and the most important disadvantageous 
factor, the dose, is increased. Besides the disadvantage of a decreasing 
contrast by increasing kV a loss of information may be the resulting 
effect. 
As is generally known for one skilled in the art of photography the 
sensitometric values and the image quality of a photographic 
light-sensitive material do not only depend on the characteristics of the 
emulsion or the composition of the material but are determined also to a 
considerable extent by the processing conditions. Contrast, speed, and 
thus also the perceptable detail is affected by processing conditions such 
as the type of the selected developer, the developer temperature, the 
degree of development and the condition of the processor. E.g. it is 
common knowledge that the slope of the characteristic curve of a 
photographic material increases with increasing degree of development. 
However once a particular limit has been reached, especially the slope at 
lower densities decreases with higher degrees of development as the fog 
caused by development rises. Film processor consistency is vital to the 
production of high quality mammograms. Variations in image quality can 
result in possible improper diagnosis and undesirable repetition of making 
mammograms. Since the current mammographic films are very dependent on the 
processing conditions, a daily processor quality control is performed in 
most hospitals, to minimize film processor inconsistency. 
On the other hand there is a general trend to enhance the speed of 
processing, especially in the field of radiography, and therefore interest 
has been focused on rapid access of radiographs, being vital in diagnosis, 
with development characteristics as independent as possible from 
development conditions. Hitherto for mammographic applications there is no 
film available that can be processed within a total processing cycle of 45 
or 38 seconds as is possible for other radiographic applications. 
Processing in such a short length of time inevitably causes archiving 
problems due to insufficient fixation and sticking phenomena due to drying 
problems. 
In the patent literature, as e.g. in U.S. Pat. Nos. 3,241,640 and 
5,112,731, it has been suggested to make use of tabular silver halide 
crystals in photographic materials to make them suitable for rapid 
processing applications. However, in applications for mammography the 
required gradations cannot be obtained with the said crystals. 
Problems concerning fog and too low a contrast at low densities, making 
definition in that region prohibitive, as well as an intolerable 
dependance of the sensitometry on processing conditions made an intensive 
investigation necessary to counter these problems in the field of 
mammographic applications. 
3. Objects of the Invention 
Therefore it is an object of this invention to provide a light-sensitive 
silver halide photographic material for applications in the field of 
mammography, said material having a very high image quality, i.e. low fog 
level, high toe contrast and overall-contrast with an enhanced sharpness. 
It is another object of this invention to provide a light-sensitive silver 
halide photographic material showing a characteristic curve, i.e. image 
quality, that is substantially uneffected by the processing conditions. 
It is a further object of this invention to provide a light-sensitive 
silver halide photographic material suitable for rapid processing within 
cycles of 45 and 38 seconds, without loss in image quality or sensitivity, 
and with good archival characteristics. 
Other objects will become apparent from the description hereinafter. 
4. Summary of the Invention 
In accordance with the present invention the above objects are accomplished 
by providing an X-ray photographic light-sensitive silver halide material 
comprising a support and one or more hydrophylic colloid layers including 
at least one light-sensitive silver halide emulsion layer comprising at 
least one gold and sulphur sensitized monodisperse Cubic silver bromide or 
silver bromoiodide emulsion with a mean crystal diameter of between 0.1 
and 2.0 .mu.m, characterised in that said at least one emulsion has been 
sensitized with a gold compound in an amount of at least 15 ppm of gold 
vs. the amount of silver, corresponding to the amount of silver halide 
coated. 
5. Detailed Description 
In accordance with this invention it has been found that especially silver 
bromide and silver bromoiodide emulsions with cubic crystal habit are 
showing favourable development characteristics with respect to high image 
quality, without the risk of high fog densities, if the said emulsions are 
chemically sensitized with high amounts of gold sensitizer. 
Even if the said emulsions with cubic crystal habit are in addition showing 
reduction sensitization due to low pAg values maintained during the 
precipitation and/or during the chemical ripening stage the sensitivity to 
fog enhancement is suppressed even though the sensitivity is increased and 
though it is generally known that the (100)-crystal faces are particularly 
sensitive to fog. 
The parameter determining whether cubic crystals are formed during the 
precipitation stage of the photographic emulsion making is the pAg of the 
solution. The pAg of the solution may be regulated by any of the means 
known in the art of emulsion making, such as the electronic control 
apparatus and method disclosed in U.S. Pat. No. 3,821,002. 
From the article "Der Einflu.beta. der Wachstumsbedingungen auf die 
Kristalltracht der Silberhalogenide" (the influene of Growth Conditions on 
the Crystalline Behaviour of Silver halides) yon E. Moisar and E. Klein, 
Bunsengesellschaft fur physikalische Chemie, Berichte 67 949-957 (1963) No 
9.10., it is known that on allowing tetradecahedral crystals of a 
homodisperse silver bromide emulsion to grow by controlled addition of 
solutions of AgNO.sub.3 and KBr, crystals of cubic form are obtained under 
conditions of low excess bromide concentration in the solution phase. With 
increasing excess of bromide, (111) surfaces are preferentially developed, 
and ultimately pure octahedral growth is observed. 
The pAg-values yielding cubic, resp. octahedral crystals depend on the 
temperature. In Table I the pAg-neutrality values are set forth for 
various temperatures, as well as the values for the formation of resp. 
cubic and octahedral crystals at these temperatures, which are above the 
pAg-neutrality values. The last column gives the `change-over pAg values`, 
i.e. the pAg values below which cubic crystals and above which octahedral 
crystal formation is taking place. Around these pAg values the crystal 
formation balances between the cubic and the octahedral structure. Values 
for pAg-neutrality and those preferred for cubic or octahedral crystal 
formation are summarized in Table I. 
TABLE I 
______________________________________ 
formation 
formation Change-over 
pAg pAg for pAg-value: 
Temp. pAg for cubic 
octahedral 
cubes to 
(.degree.C.) 
neutrality crystals crystals octaeders 
______________________________________ 
80.degree. C. 
5.0 6.5 8.8 8.1 
60.degree. C. 
5.4 7.0 9.4 8.7 
40.degree. C. 
5.8 7.5 10.1 9.2 
20.degree. C. 
6.3 8.0 10.9 9.9 
______________________________________ 
From the above table it is apparent that the cubic silver halide emulsions 
as used according to the present invention are precipitated generally 
under pAg conditions between 6.5 and 8.0. 
The silver halide emulsions formed according to the present invention 
comprise silver bromide or silver bromoiodide. Preferred silver 
bromoiodide emulsions comprise at most 10 mole % of iodide, more 
preferably at most 3 mole % and more preferably at most 1 mole %. 
A preferred embodiment of making the emulsions used according to the 
present invention involves the preparation of high-sensitive silver 
bromide or silver bromoiodide emulsions by precipitation under balanced 
double jet conditions. 
The average grain-size of the silver halide emulsions made according to the 
present invention is between 0.1 and 2.0 .mu.m, more preferably between 
0.3 and 1.5 .mu.m, and still more preferably between 0.5 and 0.75 .mu.m. 
Grain-growth restrainers or accelerators may be used during the 
precipation, and the flow rate and concentration of the solutions, the 
temperature, pAg etc. may be varied to obtain the desired particle size of 
the silver halide grains. The said particle size can be determined using 
conventional techniques e.g. as described by Trivelli and M. Smith, The 
Photographic Journal, vol. 69, 1939, p. 330-338, Loveland "ASTM symposium 
on light microscopy" 1953, p. 94-122 and Mees and James "The Theory of the 
photographic process" (1977), Chapter II. 
Monodispersed emulsions according to the present invention are prepared 
depending on the initial conditions during precipitation. Monodispersed 
emulsions are characterized in the art as emulsions of which at least 95% 
by weight or number of the grains have a diameter which is within about 
40%, preferably within about 30% of the mean grain-diameter and more 
preferably within about 10% to 20%. A preferred variation coefficient for 
emulsion grains in accordance with this invention has a value of 0.25, 
more preferred between 0.15 and 0.20, and still more preferred of 0.10, 
said variation coefficient being determined as the ratio between the 
standard deviation of the grain size and the mean crystal size. 
Silver halide grains having a narrow grain-size distribution can be 
obtained by controlling the conditions at which the silver halide grains 
are prepared using a double jet procedure. In such a procedure, the silver 
halide grains are prepared by simultaneously running an aqueous solution 
of a water-soluble silver salt for example, silver nitrate, and water 
soluble halide, for example, potassium bromide, into a rapidly agitated 
aqueous solution of a silver halide peptizer, preferably gelatin, a 
gelatin derivative or some other protein peptizer. Even colloidal silica 
may be used as a protective colloid as has been described in EP 0392092. 
In a preferred embodiment the rates of addition of the silver nitrate and 
halide salt solutions are steadily increased in such a way that no 
renucleation appears in the reaction vessel. This procedure is especially 
recommended, not only to save time but also to avoid physical ripening of 
the silver halide crystals during precipitation, the so-called Ostwald 
ripening, which gives rise to the broadening of the silver halide crystal 
distribution. During the precipitation the volume present in the vessel 
may be reduced making use of ultrafiltration techniques, which may be 
further applied to remove the by-products of grain-formation and 
grain-growth once the grains have reached their ultimate size and shape. 
Demineralized water, or water with a constant amount of halide salts to 
wash the ultrafiltrated emulsion to a desired pAg value, may be used, 
wherein the amounts of water may be added continously or in portions. 
In accordance with the present invention, the emulsions are preferably 
washed by acid-coagulation techniques using acid-coagulable gelatin 
derivatives or anionic polymeric compounds or, when precipitation occurred 
in silica medium, by certain polymers capable of forming hydrogen bridges 
with silica, in an amount sufficient to form coagulable aggregates with 
the silica particles as has been described in EP Application 517 961. 
Coagulation techniques using acid-coagulable gelatin derivatives have been 
described e.g. in U.S. Pat. Nos. 2,614,928, 2,614,929 and 2,728,662. The 
acid-coagulable gelatin derivatives are reaction products of gelatin with 
organic carboxylic or sulphonic acid chlorides, carboxylic acid 
anhydrides, aromatic isocyanates or 1,4-diketones. The use of these 
acid-coagulable gelatin derivatives generally comprises precipitating the 
silver halide grains in an aqueous solution of the acid coagulable gelatin 
derivative or in an aqueous solution of gelatin to which an acid 
coagulable gelatin derivative has been added in sufficient proportion to 
impart acid-coagulable properties to the entire mass. Alternatively, the 
gelatin derivative may be added after the stage of emulsification in 
normal gelatin, and even after the physical ripening stage, provided it is 
added in an amount sufficient to render the whole coagulable under acid 
conditions. Examples of acid-coagulable gelatin derivatives suitable for 
use in accordance with the present invention can be found e.g. in the 
United States Patents referred to above. Particularly suitable are 
phthaloyl gelatin and N-phenyl carbamoyl gelatin. 
It is also possible to wash the emulsion by coagulation techniques using 
anionic polymeric compounds. Such techniques have been described e.g. in 
German Patent DE 1,085,422. Particularly suitable anionic polymeric 
compounds are polystyrene sulphonic acid and sulphonated copolymers of 
styrene. The anionic polymers can be added to the gelatin solution before 
precipitation of the silver halide grains or after the stage of 
emulsification. They are preferably added after the grains have reached 
their ultimate size and shape, i.e. just before washing. It is also 
possible to use anionic polymers in combination with acid-coagulable 
gelatin derivatives as described in the published German Patent 
Specification No. 2,337,172 (DOS). It is preferred to use low-molecular 
weight polystyrene sulphonic acid having a molecular weight of at most 
30,000. The polystyrene sulphonic acid can be added to the gelatin 
solution from aqueous solutions preferably comprising from 5 to 20% by 
weight of polystyrene sulphonic acid. The amounts used suffice to impart 
coagulation properties to the emulsion and can easily be determined by 
those skilled in the art. 
After the precipitation stage, the silver halide emulsion comprising 
acid-coagulable gelatin derivative or anionic polymer is acidified e.g. by 
means of dilute sulphuric acid, citric acid, acetic acid, etc. so as to 
effect coagulation. Coagulation generally occurs at a pH value comprised 
between 3 and 4. The coagulum formed may be removed from the liquid by any 
suitable means, for example the supernatant liquid is decanted or removed 
by means of a siphon, whereupon the coagulum is washed out once or several 
times. 
Washing of the coagulum may occur by rinsing with mere cold water. However, 
the first wash water is preferably acidified to lower the pH of the water 
to the pH of the coagulation point. Anionic polymer e.g. polystyrene 
sulphonic acid may be added to the wash water even when an acid coagulable 
gelatin derivative has been used e.g. as described in published German 
Patent Specification (DOS) 2,337,172 mentioned hereinbefore. Alternatively 
washing may be effected by redispersing the coagulum in water at elevated 
temperature using a small amount of alkali, e.g. sodium or ammonium 
hydroxide, recoagulating by addition of an acid to reduce the pH to the 
coagulation point and subsequently removing the supernatant liquid. This 
redispersion and recoagulation operation may be repeated as many times as 
is necessary. 
After the washing operation, the coagulum is redispersed to form a 
photographic emulsion suitable for the subsequent finishing and coating 
operations by treating, preferably at a temperature within the range of 
35.degree. to 70.degree. C., with the required quantity of water, normal 
gelatin and, if necessary, alkali for a time sufficient to effect a 
complete redispersal of the coagulum. 
Instead or in addition to normal gelatin, which is preferably used, other 
known photographic hydrophilic colloids can also be used for redispersion 
e.g. a gelatin derivative as referred to above, albumin, agar-agar, sodium 
alginate, hydrolysed cellulose esters, polyvinyl alcohol, hydrophilic 
polyvinyl copolymers, colloidal silica etc. 
In accordance with the present invention the light-sensitive silver bromide 
or silver bromoiodide emulsions are chemically sensitized with a sulphur 
and gold sensitizer. This can be done as described i.a. in "Chimie et 
Physique Photographique" by P. Glafkides, in "Photographic Emulsion 
Chemistry" by G. F. Duffin, in "Making and Coating Photographic Emulsion" 
by V. L. Zelikman et al, and in "Die Grundlagen der Photographischen 
Prozesse mit Silberhalogeniden" edited by H. Frieser and published by 
Akademische Verlagsgesellschaft (1968). As described in said literature 
sulphur sensitization can be carried out by effecting the ripening in the 
presence of small amounts of compounds containing sulphur e.g. 
thiosulphate, thiocyanate, thioureas, sulphites, mercapto compounds, and 
rhodamines. 
Gold sensitization occurs by means of gold compounds, e.g. gold chloride. 
The addition of thiocyanate ions to the gold ion containing solution is 
highly preferred so that the gold compound is partially or totally 
replaced by a gold thiocyanate complex ion that is added as such to the 
emulsion containing vessel wherein the chemical sensitization is carried 
out. 
It is highly preferred in accordance with this invention to add an amount 
of gold compound corresponding to at least 15 ppm of gold vs. the amount 
of silver, corresponding to the amount of silver halide coated. In a 
preferred embodiment the amount of gold as described hereinbefore is 
preferably at least 25 ppm, and still more preferably 35 ppm. 
Additions of sulphur and gold may be carried out consecutively or 
simultaneously. In the latter case the addition of goldthiosulphate 
compounds may be recommended. 
In a preferred embodiment in accordance with this invention the weight 
ratio between added amounts of sulphur and of gold is situated between 0.5 
and 5.0 and more preferably between 0.5 and 2.0. 
In addition small amounts of compounds of Ir, Rh, Ru, Pb, Cd, Hg, Tl, Pd or 
Pt may be used. The emulsions may be sensitized in addition by means of 
reductors e.g. tin compounds as described in GB-A 789,823, amines, 
hydrazine derivatives, formamidine-sulphinic acids, and silane compounds. 
Pretreatment with small amounts of oxidizing agents before adding the 
already mentioned chemical sensitizers is highly preferred in order to 
optimize the attainable fog to sensitivity relationship. 
In accordance with the present invention compounds for preventing the 
formation of fog or stabilizing the photographic characteristics during 
the production or storage of photographic elements or during the 
photographic treatment thereof may be added. Examples of such stabilizers 
are heterocyclic nitrogen-containing stabilizing compounds as 
benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, 
chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, 
mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, 
aminotriazoles, benzotriazoles (preferably 5-methyl-benzotriazole), 
nitrobenzotriazoles, mercaptotetrazoles, in particular 
1-phenyl-5-mercapto-tetrazole, mercaptopyrimidines, mercaptotriazines, 
benzothiazoline-2-thione, oxazoline-thione, triazaindenes, tetrazaindenes 
and pentazaindenes, especially those described by Birr in Z. Wiss. Phot. 
47 (1952), pages 2-58, triazolopyrimidines such as those described in GB-A 
1,203,757, GB-A 1,209,146, JA-Appl. 75-39537, and GB-A 1,500,278, and 
7-hydroxy-s-triazolo-[1,5-a]-pyrimidines as described in U.S. Pat. No. 
4,727,017, and other compounds such as benzenethiosulphonic acid, 
benzenethiosulphinic acid, benzenethiosulphonic acid amide and other 
disulfide derivatives, and 4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene 
(TAI) as described by H. Takiguchi in J. Imag. Sci., 32(1),1988, p.20. 
Besides the addition of 3-pyrazolidinone stabilizing compounds is highly 
preferred. 
The stabilizing agents mentioned hereinbefore are usually added to the 
coating compositions, especially to the silver halide emulsion containing 
coating compositions, although the addition of said stabilizing agents to 
other hydrophilic compositions may not be excluded so as to improve the 
storage stability of the photographic material, even in severe 
circumstances of heat and humidity. So the addition of at least one 
stabilizer, e.g. 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene and/or 
3-pyrazolidinone and/or phenylmercatotriazole or -tetrazole compounds, to 
e.g. the hydrophilic protective layer is highly preferred. 
Besides in accordance with this invention especially the addition of small 
amounts of at least one of the selected stabilizers mentioned hereinbefore 
before, during or at the end of the chemical ripening is desirable. 
The chemical ripening may proceed at high temperatures, e.g. 70.degree. C., 
but preferably proceeds below 50.degree. C. 
In order to further improve the storage stability of the photographic 
material in accordance with this invention the temperature at which the 
chemical ripening proceeds is lower than 50.degree. C. and still more 
preferably lower than 47.degree. C., although this measure may deteriorate 
the sensitivity of the coated material for darkroom light. In this case a 
compensation may be found by the addition to the silver halide emulsion of 
the different chemical ripening agents at higher temperatures, e.g. 
between 55.degree. and 70.degree. C., followed by quickly decreasing the 
temperature to the preferred value below 50.degree. C. 
The cubic silver halide emulsions according to this invention may be 
spectrally sensitized with methine dyes such as those described by F. M. 
Hamer in "The Cyanine Dyes and Related Compounds", 1964, John Wiley & 
Sons. Dyes that can be used for the purpose of spectral sensitization 
include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex 
merocyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. 
Particularly valuable dyes are those belonging to the cyanine dyes, 
merocyanine dyes and complex merocyanine dyes. A survey of useful chemical 
classes of spectral sensitizing dyes is given in Research Disclosure Item 
22534. Especially preferred green sensitizers in connection with the 
present invention are 
anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbo-cyanine 
hydroxide and 
anhydro-5,5'-dichloro-3,3'-bis(n.sulfopropyl)-9-ethyloxacarbo-cyanine 
hydroxide. 
The binders of the photographic element, especially when the binder used is 
gelatin, can be hardened with appropriate hardening agents such as those 
of the epoxide type, those of the ethylenimine type, those of the 
vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol, chromium salts e.g. 
chromium acetate and chromium alum, aldehydes e.g. formaldehyde, glyoxal, 
and glutaraldehyde, N-methylol compounds e.g. dimethylolurea and 
methyloldimethylhydantoin, dioxan derivatives e.g. 2,3-dihydroxy-dioxan, 
active vinyl compounds e.g. 1,3,5-triacryloyl-hexahydro-s-triazine, active 
halogen compounds e.g. 2,4-dichloro-6-hydroxy-s-triazine, and 
mucohalogenic acids e.g. mucochloric acid and mucophenoxychloric acid. 
These hardeners can be used alone or in combination. The binders can also 
be hardened with fast-reacting hardeners such as carbamoylpyridinium 
salts. 
The photographic element of the present invention may further comprise 
various kinds of surface-active agents in the photographic emulsion layer 
or in at least one other hydrophilic colloid layer. Suitable 
surface-active agents include non-ionic agents such as saponins, alkylene 
oxides e.g. polyethylene glycol, polyethylene glycol/polypropylene glycol 
condensation products, polyethylene glycol alkyl ethers or polyethylene 
glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol 
sorbitan esters, polyalkylene glycol alkylamines or alkylamides, 
siliconepolyethylene oxide adducts, glycidol derivatives, fatty acid 
esters of polyhydric alcohols and alkyl esters of saccharides; anionic 
agents comprising an acid group such as a carboxy, sulpho, phospho, 
sulphuric or phosphoric ester group; ampholytic agents such as aminoacids, 
aminoalkyl sulphonic acids, aminoalkyl sulphates or phosphates, alkyl 
betaines, and amine-N-oxides; and cationic agents such as alkylamine 
salts, aliphatic, aromatic, or heterocyclic quaternary ammonium salts, 
aliphatic or heterocyclic ring-containing phosphonium or sulphonium salts. 
Such surface-active agents can be used for various purposes e.g. as 
coating aids, as compounds preventing electric charges, as compounds 
improving slidability, as compounds facilitating dispersive 
emulsification, as compounds preventing or reducing adhesion, and as 
compounds improving the photographic characteristics e.g higher contrast, 
sensitization, and development acceleration. 
Especially from the viewpoint of rapid processing conditions development 
acceleration may be useful, which can be accomplished with the aid of 
various compounds, preferably polyoxyalkylene derivatives having a 
molecular weight of at least 400 such as those described in e.g. U.S. Pat. 
Nos. 3,038,805, 4,038,075, 4,292,400. Especially preferred developing 
accelerators are recurrent thioether groups containing polyoxyethylenes as 
described in DE 2 360 878. The same or different or a mixture of different 
developing accelerators may be added to at least one of the hydrophilic 
layers at the emulsion side. More preferably at least one development 
accelerator is added to at least one of the protective layers, preferably 
to the topcoat layer. 
The photographic element of the present invention may further comprise 
various other additives such as e.g. compounds improving the dimensional 
stability of the photographic element, UV-absorbers, spacing agents, 
hardeners, plasticizers, antistatic agents etc. . . 
Suitable additives for improving the dimensional stability of the 
photographic element are i.a. dispersions of a water-soluble or hardly 
soluble synthetic polymer e.g. polymers of alkyl (meth)acrylates, 
alkoxy(meth) acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl 
esters, acrylonitriles, olefins, and styrenes, or copolymers of the above 
with acrylic acids, methacrylic acids, Alpha-Beta-unsaturated dicarboxylic 
acids, hydroxyalkyl (meth)acrylates, sulphoalkyl (meth) acrylates, and 
styrene sulphonic acids. 
Suitable UV-absorbers are i.a. aryl-substituted benzotriazole compounds as 
described in U.S. Pat. No. 3,533,794, 4-thiazolidone compounds as 
described in U.S. Pat. Nos. 3,314,794 and 3,352,681, benzophenone 
compounds as described in JP-A 2784/71, cinnamic ester compounds as 
described in U.S. Pat. Nos. 3,705,805 and 3,707,375, butadiene compounds 
as described in U.S. Pat. No. 4,045,229, and benzoxazole compounds as 
described in U.S. Pat. No. 3,700,455. 
In general, the average particle size of spacing agents is comprised 
between 0.2 and 10 .mu.m. Spacing agents can be soluble or insoluble in 
alkali. Alkali-insoluble spacing agents usually remain permanently in the 
photographic element, whereas alkali-soluble spacing agents usually are 
removed therefrom in an alkaline processing bath. Suitable spacing agents 
can be made i.a. of polymethyl methacrylate, of copolymers of acrylic acid 
and methyl methacrylate, and of hydroxypropylmethyl cellulose 
hexahydrophthalate. Other suitable spacing agents have been described in 
U.S. Pat. No. 4,614,708. 
The photographic material in accordance with this invention is preferably 
composed of at least one silver halide emulsion layer and at least one 
hydrophilic layer coated thereover, useful as a protective layer. Besides 
an afterlayer may be coated as an outermost layer. 
The said at least one silver halide emulsion layer may comprise at least 
one silver halide emulsion comprising silver halide crystals in accordance 
with the present invention as described hereinbefore. Mixtures of silver 
halide crystals having the same crystal size but being chemically 
sensitized differently or mixtures of crystals of a different crystal size 
may be used in at least one layer. Otherwise, silver halide emulsion 
crystals of the same size may be added to different silver halide emulsion 
layers, said silver halide emulsion crystals being chemically ripened with 
different amounts of ripening agents or silver halide crystals of a 
different size may be coated into different emulsion layers. 
In accordance with this invention the coated amounts of the silver halide 
emulsion crystals in the emulsion layer(s) described hereinbefore are 
preferably amounts corresponding to about 4.5 to 8.5 g/m.sup.2 of 
AgNO.sub.3. More preferably amounts corresponding to from 5.5 to 7.0 
g/m.sup.2 of AgNO.sub.3 are coated so as to enhance the utility in rapid 
processing conditions within 45, resp. 38 seconds, especially from the 
viewpoint of archivability, to be understood as a complete fixation by 
removal of any excess of unexposed silver halide. 
In a preferred embodiment only one silver halide emulsion layer is coated 
onto the support, having a substrate layer to provide good adhesion 
characteristics, which emulsion layer is overcoated with a protective 
antistress layer. 
Preferred compounds in the silver halide emulsion layer in accordance with 
this invention and in the protective layer coated onto the silver halide 
emulsion layer will be illustrated in the examples following further on. 
The photographic element may comprise an antistatic layer e.g. to avoid 
static discharges during coating, processing and other handlings of the 
material. Such antistatic layer may be an outermost coating, like the 
protective layer or an afterlayer, or a stratum of one or more antistatic 
agents or a coating applied directly to the film support or other support 
and overcoated with a barrier or gelatin layer. Antistatic compounds 
suitable for use in such layers are e.g. vanadium pentoxide sols, tin 
oxide sols or conductive polymers such as polyethylene oxides or a polymer 
latex and the like. 
In accordance with this invention the "gold"-sensitized silver bromide or 
silver bromoiodide emulsions coated in the emulsion layer(s) as described 
hereinbefore do reveal a low fog level, a high gradation, especially at 
low densities, and an excellent developability in different processing 
conditions, they are particularly suitable for rapid processing 
applications, especially in processing cycles of 45 and even 38 s. Besides 
the opportunity is offered to fine-tune the gradation by lowering the 
coated amount of silver halide crystals and/or enhancing the hardening 
degree of the hydrophilic binders. The said enhancement of the hardening 
degree of the coated material provides the possibility to use hardener 
free processing solutions. This opens the way to one-part package 
chemistry and concentration regeneration, reducing the volume of chemicals 
and the amount of packaging material, which is highly requested from the 
point of view of ecology. 
Further lowering the coated amount of silver halide crystals is in favour 
of archivability due to a higher fixation capacity, whereas an enhanced 
hardening degree is in favour of a lower water absorption and a higher 
drying capacity in the processing, avoiding sticking phenomena. Besides 
the lower amounts of coated silver halide crystals that are causing less 
scattering from the incident light radiating from the intensifying screen 
during exposure and the high gradations observed after processing are two 
important factors in favour of the high definition of the obtained images, 
enhancing its diagnostic value. 
The following examples illustrate the present invention.

6. Examples. 
Example 1 
A chemically sensitized fast monodisperse negative working silver 
bromoiodide emulsion having a iodide content of 1 mole % was prepared in 
the following manner. 
50 g of gelatin were added to 1.000 ml of demineralized water containing 15 
g of methionin as a growth accelerator under constant stirring at 400 rpm. 
The mixture was held for 30 minutes at room temperature and heated up to 
60.degree. C. This temperature was kept constant during the entire 
precipitation process. 
Before starting the precipitation a few drops of a diluted solution of 
potassium bromide were added so as to bring the pAg of the solution at a 
value of 7.9. 
36.5 ml of 2.94 N AgNO.sub.3 (3.65 % of the total amount of AgNO.sub.3) 
were added under the following conditions. During the first five minutes 
the flow rate of AgNO.sub.3 was kept constant at 7.3 ml/min. A mixture of 
99% KBr and 1% KI was added at a variable flow rate so as to keep the pAg 
constant at 7.9. During the following 68 minutes the flow rate of 
AgNO.sub.3 was steadily increased from 7.3 ml/min up to 21 ml/min whereas 
the pAg was kept constant at 7.9 by regulating the flow rate of the 
mixture of KBr and KI, allowing 963 ml of AgNO.sub.3 to be added. The 
latter was realised by means of an automated electronic control apparatus 
for silver halide preparation disclosed by Claes and Peelaers in 
Photographische Korrespondenz 102, Band Nr. 10/1967, p. 162. 
After five minutes the pH of the emulsion was reduced from 5.8 to 3.5 by 
adding a sufficient quantity of 6N of sulfuric acid. 
Hereupon the conventional treatment processes such as washing and 
redispersing were applied to the emulsion: pAg was adjusted to a value of 
8.4 at 45.degree. C., pH to a value of 5.8. All of the obtained silver 
halide crystals had a cubic crystal habit and an average diameter of 0.64 
.mu.m was measured. 
The emulsion was divided into 4 equal quantities. Each part was chemically 
sensitized for a period of 4 hours at 48.degree. C. in the presence of the 
same amounts of p-toluene thiosulphonate, sodium thiosulphate, sodium 
sulphite but each one with a different amount of a mixture of 
gold(III)-chloride and ammoniumthiocyanate. Differences between those four 
emulsions are summarized in Table 2. The gold concentration is expressed 
in ppm with respect to the silver concentration. 
The emulsion was spectrally sensitized with 
anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbo-cyanine 
hydroxide and stabilized with 4-hydroxy-6-methyl-l,3,3a-tetrazaindene 
before coating on a polyester support of 175 .mu.m thickness, the emulsion 
layers coated with silver halide crystals at a ratio of 6.8g/m.sup.2 
expressed as the equivalent amount of AgNO.sub.3. 
A series of photographic material samples were made by coating the emulsion 
on a polyethylene terephthalate support together with a composition for 
forming a protective gelatin layer. The amount of gelatin per square meter 
in the emulsion layers was 3.0 g, whereas in the protective layers it was 
1.1 g. 
Separate strips of the samples were subsequently exposed for the same 
exposure time to white light through a grey continuous wedge in a 
Herrnfeld Sensitometer and developed for 12 seconds in a developer having 
the following composition: 
______________________________________ 
hydroquinone 30 g 
1-phenyl-pyrazolidine-3-one 
1.5 g 
acetic acid 99% 9.5 ml 
potassiumsulphite 63.7 g 
potassiumchloride 0.8 g 
EDTA-2Na 2.1 g 
potassium carbonate 32 g 
potassiummetabisulfite 9 g 
potassium hydroxyde 14 g 
diethyleneglycol 25 ml 
6-methylbenztriazol 0.09 g 
glutardialdehyd 50% 9.5 ml 
5-nitroindazole 0.25 g 
demineralized water to make 
1 l 
______________________________________ 
The starter solution to be added had the following composition: 
______________________________________ 
acetic acid 99% 15.5 ml 
KBr 16 g 
demineralized water up to 
100 ml 
______________________________________ 
Hereupon, the developed photographic strips were fixed in a conventional 
fixing bath comprising e.g. sodium thiosulfate and potassium 
metabisulfite, and then rinsed in water and allowed to dry. 
Sensitometric properties of these film strips are given in Table II. This 
table shows the sensitometric results in terms of fog, toe contrast and 
overall contrast of the photographic strips prepared and exposed as set 
forth above and developed in the developing bath of the composition set 
forth above during an overall developing time of 12 seconds. 
The values given for the toe contrast are the gradation values measured 
from the sensitometric curve over a density range of 0.90 starting from a 
density value of 0.10 to 1.00 above fog. For the overall contrast the 
gradation is measured from the characteristic curve over a density range 
of 1.75 starting from a density value of 0.25 to 2.00 above fog. 
TABLE II 
______________________________________ 
Au- toe overall 
Emulsion 
concentration* 
fog contrast 
contrast 
______________________________________ 
1 4 33 3.43 1.89 comp. 
2 15 13 3.56 2.06 invention 
3 27 14 3.88 2.22 invention 
4 35 15 3.99 2.29 invention 
______________________________________ 
*Au in ppm, with respect to the amount of silver 
Examples No. 2, 3 and 4 clearly illustrate that the presence of gold, in an 
amount of 15 ppm or more, in the chemical sensitization, results in an 
increase in toe contrast and overall contrast, accompanied with a lower 
fog level. For mammographic applications, a toe contrast of at least 2.00 
is required. 
Example 2 
Emulsion No. 5, a comparative emulsion suitable for mammography, was 
prepared by a conventional single jet method in a vessel, held at 
40.degree. C., containing ammonium bromide, potassium bromide, potassium 
iodide and 42 g of ftaloyl gelatin. The silver nitrate, 20% of which is 
ammoniacal silver nitrate, is added at a constant rate in 9 minutes unter 
constant stirring at a rate of 400 rpm. After a physical ripening time of 
11 minutes, an additional amount of 21 g of gelatin was added. The 
obtained emulsion was an octaedric silver bromoiodide emulsion with 2% 
mole percent of iodide and with an average grain diameter of 0.50 .mu.m. 
After addition of sulphuric acid to a pH value of 3.5 stirring was stopped 
and after sedimentation the supernatant liquid was removed. The washing 
procedure was started after a scrape-rudder was installed and after 
addition of polystyrene sulphonic acid in the first turn to get a 
quantitative flocculate without silver losses. During redispersion of the 
emulsion 150 g of gelatine was added. The emulsion was chemically 
sensitized with sulphur and gold at 47.degree. C. for 5 hours and was 
stabilized with 4-hydroxy-6-methyl-l,3,3a-tetrazaindene before coating on 
a polyester support of 175 .mu.m thickness, the emulsion layers coated at 
a ratio of 6.8g/m.sup.2 expressed as the equivalent amount of AgNO.sub.3. 
The emulsions No. 6 and 7 correspond to the respective emulsions 1 and 4 of 
table II. 
Separate strips of the samples coated as described hereinbefore were 
subsequently exposed to white light through a grey continuous wedge in a 
Hernfeld Sensitometer. 
The three different materials, coated with emulsion Nos. 5, 6, and 7 
respectively, were processed in different types of developer, at different 
temperatures. The said different developer types had the following 
composition: 
dev.1: developer composition as descriped in example 1 
dev.2: a developer with the following composition: 
______________________________________ 
potassiumhydroxide 29.6 g 
potassiumsulphite 15 g 
boric acid 18.7 g 
sodium sulphite 25 g 
EDTA-2Na 1.5 g 
hydroquinone 20 g 
1-phenyl-5-mercaptotetrazole 
20 mg 
sodium bromide 2 g 
acetic acid 8.8 ml 
1-phenyl-pyrazolidine-3-one 
0.9 g 
6-nitrobenzimidazole 90 mg 
polyglycol 200 0.25 ml 
glutardialdehyde 50% 7.5 ml 
potassiummetabisulphite 10 g 
demineralized water to make 
1 l 
______________________________________ 
Starter solution to be added: 
______________________________________ 
sodiumbromide 36 g 
acetic acid 99% 20 ml 
demineralized water up to 
100 ml 
______________________________________ 
dev.3: Adefo Mix S, trade name product of Adefo 
dev.4: a developer with the following composition: 
______________________________________ 
EDTA-2Na 1.6 g 
potassiumhydroxide 33.6 g 
sodiummetabisulphite 30 g 
hydroquinone 16 g 
6-methylbenztriazol 48 mg 
sodiumtetraborate.10 aq 10.6 g 
acetic acid 99% 6.2 ml 
1-phenyl-pyrazolidine-3-one 
0.9 g 
6-nitrobenzimidazole 60 mg 
glutardialdehyd 50% 6.4 ml 
potassiummetabisulphite 4.6 g 
______________________________________ 
Starter solution to be added: 
______________________________________ 
acetic acid 99% 16 ml 
potassiumbromide 16 g 
potassiumiodide 40 mg 
demineralized water up to 
100 ml 
______________________________________ 
dev.5: Russel AUTO-MAT 2000, trade name product of L. B. Russel Chemicals 
de Mexico 
Emulsion Nos. 5,6 and 7 were processed in 16 different processing 
conditions. Except for processing condition 1 (where the processor was a 
EK M6/5 automatic processor) the processing was performed in a EK M6/3 
automatic processor, both processors being trade name products marketed by 
Eastman Kodak. 
In Table III the base+fog density (B+F) and the speed values (absolute 
values corresponding to a density of 1 above fog, expressed in log Ixt) 
are summarized for all different processing conditions in the different 
developers described hereinbefore and at different temperatures, given in 
column 2 of Table III. In the last row but one, the calculated standard 
deviation is given. In the lowest row the total range of all the values 
for one emulsion is shown. 
TABLE III 
______________________________________ 
B + F B + F B + F Speed Speed Speed 
emul. emul. emul. emul. emul. emul. 
dev. T 5 6 7 5 6 7 
type (.degree.C.) 
comp. comp. inven. 
comp. comp. inven. 
______________________________________ 
1 33 189 219 199 174 168 167 
2 34 182 194 186 189 184 180 
2 37 185 201 190 177 177 175 
2 40 188 207 192 167 170 171 
3 34 182 203 191 186 177 176 
3 37 187 210 194 174 170 170 
3 40 196 228 203 162 163 166 
4 34 183 196 185 192 182 179 
4 37 184 202 188 184 176 175 
4 40 190 215 192 176 170 171 
1 34 185 200 187 182 175 174 
1 37 188 190 208 174 169 171 
1 40 194 221 195 167 163 168 
5 34 192 228 198 182 172 174 
5 37 201 245 208 176 168 171 
5 40 221 274 223 170 164 169 
* 9 20 9 8 6 4 
** 39 80 38 30 21 14 
______________________________________ 
*standard deviation 
**range 
The results for the toe contrast and for the overall contrast (as defined 
in example 1) in the 16 different processing condition are summarized in 
table IV. 
TABLE IV 
______________________________________ 
Toe Toe Toe Over. Over. Over. 
contr. contr. 
contr. 
contr. 
contr. 
contr. 
emul. emul. emul. emul. emul. emul. 
dev. T 5 6 7 5 6 7 
type (.degree.C.) 
comp. comp. inven. 
comp. comp. inven. 
______________________________________ 
1 33 200 197 220 359 369 364 
2 34 202 204 232 327 349 356 
2 37 219 204 228 357 356 357 
2 40 237 203 229 388 360 358 
3 34 192 191 217 325 346 358 
3 37 203 196 218 351 365 375 
3 40 218 196 217 370 362 370 
4 34 173 194 226 266 356 360 
4 37 178 188 216 289 353 350 
4 40 171 184 208 303 356 351 
1 34 197 197 224 360 378 375 
1 37 203 195 224 374 380 375 
1 40 206 192 221 391 374 374 
5 34 175 178 209 306 329 339 
5 37 176 180 209 309 333 342 
5 40 176 181 211 320 333 341 
* 19 8 7 36 15 12 
** 66 26 24 125 51 36 
______________________________________ 
*standard deviation 
**range 
From Tables III and IV is clear that for emulsion 7, prepared according to 
this invention, the range for the sensitometric data such as speed, toe 
contrast and overall contrast is much lower than for the comparative 
emulsions Nos. 5 and 6. Especially the sensitometric behaviour of emulsion 
No. 5, bearing octahedral silver bromoiodide crystals, is strongly 
influenced upon the processing conditions. Also emulsion No. 6, 
characterized by the presence of cubic crystal, chemically sensitized with 
less then 15 ppm Au, is more effected by the processing conditions than 
emulsion No. 7, according to the invention. The differences are especially 
reflected by the differences in the base +fog density and speed values. 
Example 3 
Emulsions 8 and 9 correspond to the respective emulsions 1 and 4 of Table 
II. 
Emulsion 10 is the same as 9, except that it was coated at a ratio of 5.5 
g/m.sup.2 expressed as the equivalent amount of AgNO.sub.3. 
Emulsions 11,12 and 13 are the same as Emulsion 10, except for the ratio 
hardening agent to gelatine. The different ratios are summarised in Table 
V. 
Separate strips of these 6 samples (Emulsions 8-13) were subsequently 
exposed for the same exposure time to white light through a grey 
continuous wedge in a Hernnfeld sensitometer, and processed in a Curix HT 
530, trade name product of Agfa-Gevaert, in processing cycles of 90, 45 
and 38 seconds, with as developer a one-part package developer without 
hardening agent, and as fixer a one-part package fixer without hardening 
agent. The processing cycle is defined as the period of time from the 
input of an exposed film in the processor to the moment the film appears 
at the dryer exit. 
Composition of the developer: -concentrated part: 
______________________________________ 
water 200 ml 
potassium bromide 6 g 
potassium sulphite (65% solution) 
247 g 
ethylenediaminetetraacetic acid, 
9.6 g 
sodium salt, trihydrate 
hydroquinone 112 g 
5-methylbenzotriazole 0.076 g 
1-phenyl-5-mercaptotetrazole 
0.040 g 
sodiumtetraborate (decahydrate) 
18 g 
potassium carbonate 38 g 
potassium hydroxyde 42 g 
diethylene glycol 100 g 
potassium iodide 0.088 g 
4-hydroxymethyl-4methyl-1phenyl- 
12 g 
3-pyrazolidinone 
Water to make 1 liter 
______________________________________ 
For initiation of the processing one part of the concentrated developer was 
mixed with 3 parts of water. No starter was added. The pH of this mixture 
was 10.40 at 25.degree. The toe contrast and overall-contrast (as defined 
in example 1) and the archivability for the different samples all 
summarized in Table V. The archivability test was done as following: a 
sheet of unexposed film of each sample was processed in all the different 
processing cycles. A drop of a residual hypo test solution is placed on 
the film. This residual hypo test solution is composed of 10 grams of 
silver nitrate and of 30 ml of acetic acid (99%) and sufficient distilled 
water to make 1 liter of solution. After the drop was placed on the 
unexposed film, the solution stand for two minutes on the film, after 
those two minutes the excessive solution amount was blot off. The density 
difference, between the density on the spot where the solution was placed 
and the density on the strip next to the spot, was measured with a Macbeth 
TD903 densitometer. This density difference is a measure for the amount of 
residual hypo in the film. The said density difference,multiplied with 11, 
is a measure for the amount of ammoniumthiosulphate (in mg/m.sup.2) 
restained in the film. To ensure a good archivability, this value should 
not exceed 175. 
TABLE V 
______________________________________ 
proc. 
Em. AgNO.sub.3 
Formal- cycle 
Toe Overall 
Archiv- 
No. in g/m.sup.2 
dehyde* (sec) 
contrast 
contrast 
ability 
______________________________________ 
8 6.8 21 90 179 322 44 
9 6.8 25 90 214 358 33 
10 5.5 29 90 203 318 33 
11 5.5 24.6 90 210 329 33 
12 5.5 20.3 90 213 331 33 
13 5.5 14.5 90 224 343 33 
8 6.8 21 45 181 308 154 
9 6.8 25 45 213 356 247 
10 5.5 29 45 205 330 55 
11 5.5 24.6 45 207 332 33 
12 5.5 20.3 45 205 335 44 
13 5.5 14.5 45 220 357 44 
8 6.8 21 38 147 294 501 
9 6.8 25 38 228 369 451 
10 5.5 29 38 202 323 50 
11 5.5 24.6 38 206 333 60 
12 5.5 20.3 38 206 338 55 
13 5.5 14.5 38 216 354 70 
______________________________________ 
*expressed as mg formaldehyde/gram of gelatin 
As it is clear from Table V, a material with an emulsion according the 
invention (emulsions 9 to 13) is suitable for mammographic applications, 
even in short processing cycles of 45 and 38 seconds, with one-package 
hardener-free developer and fixer. With the invention, an adequate toe 
contrast and average contrast is reached, even in the short developing 
cycle. With 6.8 g AgNO.sub.3 /m.sup.2 the archivability is above the 
limit. Decreasing the amount of silver/m.sup.2 wich is possible with this 
invention because of the high toe contrast and overall contrast, results 
in a sufficient archivability of from 10 to 20 years normal storage 
conditions, i.e. moderate values of temperatures and relative humidities.